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Sample records for rubbia presente au

  1. Anomalous and galactic cosmic ray intensities at 1 AU during the present solar minimum

    NASA Astrophysics Data System (ADS)

    Leske, Richard; Cummings, A. C.; Cohen, Christina; Mewaldt, R. A.; Stone, E. C.; Wiedenbeck, Mark; von Rosenvinge, Tycho

    Anomalous cosmic ray (ACR) intensities at 1 AU at solar minimum typically track galactic cosmic ray (GCR) intensities as measured by neutron monitors. Throughout the current A<0 cycle, however, the ACR intensities have consistently been a factor of 3-4 lower than expected from scaling neutron monitor rates; a similar discrepancy seems to have been present during the last A<0 period in the mid-1980's. Also, although the present solar minimum has been deep and long-lasting in terms of sunspot numbers and major solar particle events, ACR intensities remain almost a factor of 2 below their maximum values during each of the last two A>0 solar minima and have just barely reached the last A<0 levels. This is probably associated with the fact that ACRs drift inward along the heliospheric current sheet (HCS) during A<0 cycles, and the tilt of the current sheet has been relatively high, dropping below 15° for only 3 solar rotations starting in August 2009. However, while ACR intensities are typical or low, GCR intensities are at the highest levels recorded during the last 50 years, indicating these particles are not being as heavily modulated during their transport from the outer heliosphere. Using neutron monitor data along with ACR and GCR measurements from the ACE spacecraft, we find that both ACR and GCR intensities are actually much higher now for a given HCS tilt angle than they were during the last A<0 cycle. We present updated measurements of the ACR and GCR intensity variations at 1 AU through-out the solar cycle and discuss possible explanations for the different behavior between the present A<0 epoch and the previous one.

  2. Two-photon photodynamic properties of TBO-AuNR-in-shell nanoparticles (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wu, Cheng-Han; Yeh, Chen-Sheng; Cheng, Fong-Yu; Tsai, Zen-Uong; Liu, Tzu-Ming

    2016-03-01

    Photodynamic therapy (PDT) is a light-activated chemotherapeutic treatment that utilizes singlet oxygen and reactive oxygen species induced oxidative reactions to react with surrounding biological substrates, which either kills or irreversibly damages malignant cells. We used multiphoton nonlinear optical microscopy to observe the photo-dynamic effects of TBO-AuNR-in-shell NPs. Excited by femtosecond Cr:forsterite laser operating at 1230nm, singlet oxygen were generated through a plasmon-enhanced two-photon nonlinear optical process. For cells took up NPs, this photodynamic effect can kill the cell. From nonlinear optical microscopy images, we found they shrunk after 3 minutes of illumination.

  3. USGS exploration geochemistry studies at the Pebble porphyry Cu-Au-Mo deposit, Alaska-pdf of presentation

    USGS Publications Warehouse

    Eppinger, Robert G.; Kelley, Karen D.; Fey, David L.; Giles, Stuart A.; Minsley, Burke J.; Smith, Steven M.

    2010-01-01

    From 2007 through 2010, scientists in the U.S. Geological Survey (USGS) have been conducting exploration-oriented geochemical and geophysical studies in the region surrounding the giant Pebble porphyry Cu-Au-Mo deposit in southwestern Alaska. The Cretaceous Pebble deposit is concealed under tundra, glacial till, and Tertiary cover rocks, and is undisturbed except for numerous exploration drill holes. These USGS studies are part of a nation-wide research project on evaluating and detecting concealed mineral resources. This report focuses on exploration geochemistry and comprises illustrations and associated notes that were presented as a case study in a workshop on this topic. The workshop, organized by L.G. Closs and R. Glanzman, is called 'Geochemistry in Mineral Exploration and Development,' presented by the Society of Economic Geologists at a technical conference entitled 'The Challenge of Finding New Mineral Resources: Global Metallogeny, Integrative Exploration and New Discoveries,' held at Keystone, Colorado, October 2-5, 2010.

  4. d + Au hadron correlation measurements at PHENIX

    SciTech Connect

    Anne M. Sickles

    2014-05-13

    In these proceedings, we discuss recent results from d + Au collisions in PHENIX ridge related measurements and their possible hydrodynamic origin. We present the v2 at midrapidity and measurements of the pseudorapidity dependence of the ridge, distinguishing between the d-going and Au-going directions. We investigate the possible geometrical origin by comparing v2 in d + Au to that in p + Pb, Au + Au and Pb + Pb collisions. Future plans to clarify the role of geometry in small collision systems at RHIC are discussed.

  5. Antibacterial Au nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Wu, Songmei; Zuber, Flavia; Brugger, Juergen; Maniura-Weber, Katharina; Ren, Qun

    2016-01-01

    We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all the Au nanostructures, regardless their shapes, exhibited similar excellent antibacterial properties. A comparison of live cells attached to nanotopographic surfaces showed that the number of live S. aureus cells was <1% of that from flat and rough reference surfaces. Our micro/nanofabrication process is a scalable approach based on cost-efficient self-organization and provides potential for further developing functional surfaces to study the behavior of microbes on nanoscale topographies.We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It

  6. Flow in Au+Au collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Belt Tonjes, Marguerite; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J.-L.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wolfs, F. L. H.; Wosiek, B.; Wozniak, K.; Wuosmaa, A. H.; Wyslouch, B.

    2004-08-01

    The study of flow can provide information on the initial state dynamics and the degree of equilibration attained in heavy-ion collisions. This contribution presents results for both elliptic and directed flow as determined from data recorded by the PHOBOS experiment in Au+Au runs at RHIC at \\sqrt{s_{{\\rm NN}}} = 19.6, 130 and 200 GeV. The PHOBOS detector provides a unique coverage in pseudorapidity for measuring flow at RHIC. The systematic dependence of flow on pseudorapidity, transverse momentum, centrality and energy is discussed.

  7. Synthesis and characterization in AuCu–Si nanostructures

    SciTech Connect

    Novelo, T.E.; Amézaga-Madrid, P.; Maldonado, R.D.; Oliva, A.I.; Alonzo-Medina, G.M.

    2015-03-15

    Au/Cu bilayers with different Au:Cu concentrations (25:75, 50:50 and 75:25 at.%) were deposited on Si(100) substrates by thermal evaporation. The thicknesses of all Au/Cu bilayers were 150 nm. The alloys were prepared by thermal diffusion into a vacuum oven with argon atmosphere at 690 K during 1 h. X-ray diffraction analysis revealed different phases of AuCu and CuSi alloys in the samples after annealing process. CuSi alloys were mainly obtained for 25:75 at.% samples, meanwhile the AuCuII phase dominates for samples prepared with 50:50 at.%. Additionally, the Au:Cu alloys with 75:25 at.%, produce Au{sub 2}Cu{sub 3} and Au{sub 3}Cu phases. The formed alloys were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) to study the morphology and the elemental concentration of the formed alloys. - Highlights: • AuCu/Si alloy thin films were prepared by thermal diffusion. • Alloys prepared with 50 at.% of Au produce the AuCuII phase. • Alloys prepared with 75 at.% of Au produce Au{sub 3}Cu and Au{sub 2}Cu{sub 3} phases. • All alloys present diffusion of Si and Cu through the CuSi alloy formation.

  8. Charged hadron transverse momentum distributions in Au+Au collisions at √ SNN = 200 GeV

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.; van Nieuwenhuizen, Gerrit; PHOBOS Collaboration

    2003-04-01

    We present transverse momentum distributions of charged hadrons produced in Au+Au collisions at √ SNN = 200 GeV. The evolution of the spectra for transverse momenta p T from 0.25 to 5 GeV/C is studied as a function of collision centrality. We find a significant change of the spectral shape between proton-antiproton and peripheral Au+Au collisions. When comparing peripheral to central Au+Au collisions, we find that the yields at the highest p T exhibit approximate scaling with the number of participating nucleons, rather than scaling with the number of binary collisions.

  9. Antibacterial Au nanostructured surfaces.

    PubMed

    Wu, Songmei; Zuber, Flavia; Brugger, Juergen; Maniura-Weber, Katharina; Ren, Qun

    2016-02-01

    We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all the Au nanostructures, regardless their shapes, exhibited similar excellent antibacterial properties. A comparison of live cells attached to nanotopographic surfaces showed that the number of live S. aureus cells was <1% of that from flat and rough reference surfaces. Our micro/nanofabrication process is a scalable approach based on cost-efficient self-organization and provides potential for further developing functional surfaces to study the behavior of microbes on nanoscale topographies. PMID:26648134

  10. d + Au hadron correlation measurements from PHENIX

    NASA Astrophysics Data System (ADS)

    Sickles, Anne M.

    2015-01-01

    Recent observations of extended pseudorapidity correlations at the LHC in p+p and p+Pb collisions are of great interest. Here we present related results from d+Au collisions at PHENIX. We present the observed v2 and discuss the possible origin in the geometry of the collision region. We also present new measurements of the pseudorapidity dependence of the ridge in d+Au collision. Future plans to clarify the role of geometry in small collision systems using 3 He + Au collisions are discussed.

  11. Controlled Synthesis of Au@AgAu Yolk-Shell Cuboctahedra with Well-Defined Facets.

    PubMed

    Londono-Calderon, Alejandra; Bahena, Daniel; Yacaman, Miguel J

    2016-08-01

    The synthesis of Au@AgAu yolk-shell cuboctahedra nanoparticles formed by galvanic replacement in a seed-mediated method is described. Initially, single-crystal Au seeds are used for the formation of Au@Ag core-shell nanocubes, which serve as the template material for the deposition of an external Au layer. The well-controlled synthesis yields the formation of cuboctahedra nanoparticles with smooth inner and outer Au/Ag surfaces. The deposition/oxidation process is described to understand the formation of cuboctahedra and octahedra nanoparticles. The Au core maintains the initial morphology of the seed and remains static at the center of the yolk-shell because of residual Ag. Structural analysis of the shell indicates intrinsic stacking faults (SFs) near the surface. Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) compositional analysis show an Au-Ag nonordered alloy forming the shell. The three-dimensional structure of the nanoparticles presented open facets on the [111] as observed by electron tomography SIRT reconstruction over a stack of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images. The geometrical model was validated by analyzing the direction of streaks in coherent nanobeam diffraction (NBD). The catalytic activity was evaluated using a model reaction based on the reduction of 4-nitrophenol (4-NTP) by NaBH4 in the presence of Au@AgAu yolk-shell nanoparticles. PMID:27385583

  12. Ultra-relativistic Au+Au and d+Au collisions:

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Hauer, M.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Seals, H.; Sedykh, I.; Skulski, W.; Smith, C. E.; Stankiewicz, M. A.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J.-L.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wenger, E.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    In this talk I will review PHOBOS data on charged particle multiplicities, obtained in Au+Au and d+Au collisions at RHIC. The general features of the Au+Au pseudorapidity distributions results will be discussed and compared to those of /line{p}p collisions. The total charged particle multiplicity, scaled by the number of participant pairs, is observed to be about 40% higher in Au+Au collisions than in /line{p}p and d+Au systems, but, surprisingly at the same level of e+e- collisions. Limiting fragmentation scaling is seen to be obeyed in Au+Au collisions.

  13. Charged hadron transverse momentum distributions in Au+Au collisions at S=200 GeV

    NASA Astrophysics Data System (ADS)

    Roland, Christof; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    2003-03-01

    We present transverse momentum distributions of charged hadrons produced in Au+Au collisions at sqrt(s_NN) = 200 GeV. The evolution of the spectra for transverse momenta p_T from 0.25 to 5GeV/c is studied as a function of collision centrality over a range from 65 to 344 participating nucleons. We find a significant change of the spectral shape between proton-antiproton and peripheral Au+Au collisions. Comparing peripheral to central Au+Au collisions, we find that the yields at the highest p_T exhibit approximate scaling with the number of participating nucleons, rather than scaling with the number of binary collisions.

  14. Centrality dependence of direct photon production in (square root)S(NN) = 200 GeV Au + Au collisions.

    PubMed

    Adler, S S; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Alexander, J; Amirikas, R; Aphecetche, L; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, R; Babintsev, V; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bazilevsky, A; Belikov, S; Berdnikov, Y; Bhagavatula, S; Boissevain, J G; Borel, H; Borenstein, S; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Chai, J-S; Chand, P; Chang, W C; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Choi, J; Choudhury, R K; Chujo, T; Cianciolo, V; Cobigo, Y; Cole, B A; Constantin, P; d'Enterria, D; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Devismes, A; Dietzsch, O; Drapier, O; Drees, A; du Rietz, R; Durum, A; Dutta, D; Efremenko, Y V; El Chenawi, K; Enokizono, A; En'yo, H; Esumi, S; Ewell, L; Fields, D E; Fleuret, F; Fokin, S L; Fox, B D; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fung, S-Y; Garpman, S; Ghosh, T K; Glenn, A; Gogiberidze, G; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Perdekamp, M Grosse; Guryn, W; Gustafsson, H-A; Hachiya, T; Haggerty, J S; Hamagaki, H; Hansen, A G; Hartouni, E P; Harvey, M; Hayano, R; Hayashi, N; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hibino, M; Hill, J C; Holzmann, W; Homma, K; Hong, B; Hoover, A; Ichihara, T; Ikonnikov, V V; Imai, K; Isenhower, D; Ishihara, M; Issah, M; Isupov, A; Jacak, B V; Jang, W Y; Jeong, Y; Jia, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kametani, S; Kamihara, N; Kang, J H; Kapoor, S S; Katou, K; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D H; Kim, D J; Kim, D W; Kim, E; Kim, G-B; Kim, H J; Kistenev, E; Kiyomichi, A; Kiyoyama, K; Klein-Boesing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kopytine, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kuberg, C H; Kurita, K; Kuroki, Y; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Ladygin, V; Lajoie, J G; Lebedev, A; Leckey, S; Lee, D M; Lee, S; Leitch, M J; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Liu, Y; Maguire, C F; Makdisi, Y I; Malakhov, A; Manko, V I; Mao, Y; Martinez, G; Marx, M D; Masui, H; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E; Messer, F; Miake, Y; Milan, J; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mühlbacher, F; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagle, J L; Nakamura, T; Nandi, B K; Nara, M; Newby, J; Nilsson, P; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, K; Ono, M; Onuchin, V; Oskarsson, A; Otterlund, I; Oyama, K; Ozawa, K; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Parmar, A; Pate, S F; Peitzmann, T; Peng, J-C; Peresedov, V; Pinkenburg, C; Pisani, R P; Plasil, F; Purschke, M L; Purwar, A K; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosnet, P; Ryu, S S; Sadler, M E; Saito, N; Sakaguchi, T; Sakai, M; Sakai, S; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Semenov, V; Seto, R; Shaw, M R; Shea, T K; Shibata, T-A; Shigaki, K; Shiina, T; Silva, C L; Silvermyr, D; Sim, K S; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Sullivan, J P; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarján, P; Tepe, J D; Thomas, T L; Tojo, J; Torii, H; Towell, R S; Tserruya, I; Tsuruoka, H; Tuli, S K; Tydesjö, H; Tyurin, N; van Hecke, H W; Velkovska, J; Velkovsky, M; Veszprémi, V; Villatte, L; Vinogradov, A A; Volkov, M A; Vznuzdaev, E; Wang, X R; Watanabe, Y; White, S N; Wohn, F K; Woody, C L; Xie, W; Yang, Y; Yanovich, A; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zhou, S J; Zolin, L

    2005-06-17

    The first measurement of direct photons in Au + Au collisions at (square root)S(NN) = 200 GeV is presented. The direct photon signal is extracted as a function of the Au + Au collision centrality and compared to next-to-leading order perturbative quantum chromodynamics calculations. The direct photon yield is shown to scale with the number of nucleon-nucleon collisions for all centralities. PMID:16090462

  15. Charged hadron transverse momentum distributions in Au+Au collisions at √sNN=200 GeV

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Lee, J. W.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    2004-01-01

    We present transverse momentum distributions of charged hadrons produced in Au+Au collisions at sNN=200 GeV. The spectra were measured for transverse momenta pT from 0.25 to 4.5 GeV/c in a pseudorapidity range of 0.2<η<1.4. The evolution of the spectra is studied as a function of collision centrality, from 65 to 344 participating nucleons. The results are compared to data from proton-antiproton collisions and Au+Au collisions at lower RHIC energies. We find a significant change of the spectral shape between proton-antiproton and semi-peripheral Au+Au collisions. Comparing semi-peripheral to central Au+Au collisions, we find that the yields at high pT exhibit approximate scaling with the number of participating nucleons, rather than scaling with the number of binary collisions.

  16. Collective flow in Au + Au collisions

    SciTech Connect

    Ritter, H.G.; EOS Collaboration

    1994-05-01

    Based on a preliminary sample of Au + Au collisions in the EOS time projection chamber at the Bevalac, we study sideward flow as a function of bombarding energy between 0.25A GeV and 1.2A GeV. We focus on the increase in in-plane transverse momentum per nucleon with fragment mass. We also find event shapes to be close to spherical in the most central collisions, independent of bombarding energy and fragment mass up to {sup 4}He.

  17. Identified particles in Au+Au collisions at S=200 GeV

    NASA Astrophysics Data System (ADS)

    Phobos Collaboration; Wosiek, Barbara; Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Ballintijn, M.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    2003-03-01

    The yields of identified particles have been measured at RHIC for Au+Au collisions at S=200 GeV using the PHOBOS spectrometer. The ratios of antiparticle to particle yields near mid-rapidity are presented. The first measurements of the invariant yields of charged pions, kaons and protons at very low transverse momenta are also shown.

  18. Structural, electronic and magnetic properties of Au-based monolayer derivatives in honeycomb structure

    NASA Astrophysics Data System (ADS)

    Kapoor, Pooja; Sharma, Munish; Kumar, Ashok; Ahluwalia, P. K.

    2016-05-01

    We present electronic properties of atomic layer of Au, Au2-N, Au2-O and Au2-F in graphene-like structure within the framework of density functional theory (DFT). The lattice constant of derived monolayers are found to be higher than the pristine Au monolayer. Au monolayer is metallic in nature with quantum ballistic conductance calculated as 4G0. Similarly, Au2-N and Au2-F monolayers show 4G0 and 2G0 quantum conductance respectively while semiconducting nature with calculated band gap of 0.28 eV has been observed for Au2-O monolayer. Most interestingly, half metalicity has been predicted for Au2-N and Au2-F monolayers. Our findings may have importance for the application of these monolayers in nanoelectronic and spintronics.

  19. Universality in fragment inclusive yields from Au+Au collisions

    NASA Astrophysics Data System (ADS)

    Insolia, A.; Tuvè, C.; Albergo, S.; Bieser, F.; Brady, F. P.; Caccia, Z.; Cebra, D.; Chacon, A. D.; Chance, J. L.; Choi, Y.; Costa, S.; Elliott, J. B.; Gilkes, M.; Hauger, J. A.; Hirsch, A. S.; Hjort, E. L.; Justice, M.; Keane, D.; Kintner, J.; Lisa, M.; Matis, H. S.; McMahan, M.; McParland, C.; Olson, D. L.; Partlan, M. D.; Porile, N. T.; Potenza, R.; Rai, G.; Rasmussen, J.; Ritter, H. G.; Romero, J. L.; Russo, G. V.; Scharenberg, R.; Scott, A.; Shao, Y.; Srivastava, B. K.; Symons, T. J. M.; Tincknell, M. L.; Wang, S.; Warren, P. G.; Wieman, H. H.; Wolf, K. L.

    2001-11-01

    The inclusive light fragment (Z⩽7) yield data in Au+Au reactions, measured by the EOS Collaboration at the LBNL Bevalac, are presented and discussed. For peripheral collisions the measured charge distributions develop progressively according to a power law which can be fitted by a single τ exponent independently of the bombarding energy in the range 250-1200 A MeV. In addition to this universal feature, we observe that the location of the maximum in the individual yields of different charged fragments shift towards lower multiplicity as the fragment charge increases from Z=3 to Z=7. This trend is common to all six measured beam energies. Moments of charge distributions and correlations among different moments are reported. Finally, the THe,DT thermometer has been constructed for central and peripheral collisions using the double yield ratios of He and D, T projectile fragments. The measured nuclear temperatures are in agreement with experimental findings in other fragmentation reactions.

  20. Global polarization measurement in Au+Au collisions

    NASA Astrophysics Data System (ADS)

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Baumgart, S.; Belaga, V. V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Benedosso, F.; Betts, R. R.; Bhardwaj, S.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Blyth, S.-L.; Bombara, M.; Bonner, B. E.; Botje, M.; Bouchet, J.; Brandin, A. V.; Burton, T. P.; Bystersky, M.; Cai, X. Z.; Caines, H.; Sánchez, M. Calderón De La Barca; Callner, J.; Catu, O.; Cebra, D.; Cervantes, M. C.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, S. U.; Clarke, R. F.; Codrington, M. J. M.; Coffin, J. P.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; Moura, M. M. De; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; Didenko, L.; Dietel, T.; Djawotho, P.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, F.; Dunin, V. B.; Dunlop, J. C.; Mazumdar, M. R. Dutta; Edwards, W. R.; Efimov, L. G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C. A.; Gaillard, L.; Ganti, M. S.; Garcia-Solis, E.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. N.; Gos, H.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S. M.; Guimaraes, K. S. F. F.; Gupta, A.; Gupta, N.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; He, W.; Heinz, M.; Henry, T. W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D. J.; Hollis, R. S.; Horner, M. J.; Huang, H. Z.; Hughes, E. W.; Humanic, T. J.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jones, P. G.; Judd, E. G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V. Yu.; Kiryluk, J.; Kisiel, A.; Kislov, E. M.; Klein, S. R.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kouchpil, V.; Kowalik, K. L.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Kuhn, C.; Kulikov, A. I.; Kumar, A.; Kurnadi, P.; Kuznetsov, A. A.; Lamont, M. A. C.; Landgraf, J. M.; Lange, S.; Lapointe, S.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Lehocka, S.; Levine, M. J.; Li, C.; Li, Q.; Li, Y.; Lin, G.; Lin, X.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ludlam, T.; Lynn, D.; Ma, G. L.; Ma, J. G.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Martin, L.; Matis, H. S.; Matulenko, Yu. A.; McShane, T. S.; Meschanin, A.; Millane, J.; Miller, M. L.; Minaev, N. G.; Mioduszewski, S.; Mischke, A.; Mitchell, J.; Mohanty, B.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Nepali, C.; Netrakanti, P. K.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okorokov, V.; Olson, D.; Pachr, M.; Pal, S. K.; Panebratsev, Y.; Pavlinov, A. I.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Planinic, M.; Pluta, J.; Poljak, N.; Porile, N.; Poskanzer, A. M.; Potekhin, M.; Potrebenikova, E.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Putschke, J.; Qattan, I. A.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Relyea, D.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Sahoo, R.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sarsour, M.; Sazhin, P. S.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shen, W. Q.; Shimanskiy, S. S.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Smirnov, N.; Snellings, R.; Sorensen, P.; Sowinski, J.; Speltz, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, T. D. S.; Staszak, D.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Z.; Surrow, B.; Symons, T. J. M.; Toledo, A. Szanto De; Takahashi, J.; Tang, A. H.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Timoshenko, S.; Tokarev, M.; Trainor, T. A.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; Buren, G. Van; Kolk, N. Van Der; Leeuwen, M. Van; Molen, A. M. Vander; Varma, R.; Vasilevski, I. M.; Vasiliev, A. N.; Vernet, R.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Waggoner, W. T.; Wang, F.; Wang, G.; Wang, J. S.; Wang, X. L.; Wang, Y.; Webb, J. C.; Westfall, G. D.; , C. Whitten, Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, J.; Wu, Y.; Xu, N.; Xu, Q. H.; Xu, Z.; Yepes, P.; Yoo, I.-K.; Yue, Q.; Yurevich, V. I.; Zawisza, M.; Zhan, W.; Zhang, H.; Zhang, W. M.; Zhang, Y.; Zhang, Z. P.; Zhao, Y.; Zhong, C.; Zhou, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zubarev, A. N.; Zuo, J. X.

    2007-08-01

    The system created in noncentral relativistic nucleus-nucleus collisions possesses large orbital angular momentum. Because of spin-orbit coupling, particles produced in such a system could become globally polarized along the direction of the system angular momentum. We present the results of Λ and Λ¯ hyperon global polarization measurements in Au+Au collisions at sNN=62.4 and 200 GeV performed with the STAR detector at the BNL Relativistic Heavy Ion Collider (RHIC). The observed global polarization of Λ and Λ¯ hyperons in the STAR acceptance is consistent with zero within the precision of the measurements. The obtained upper limit, |PΛ,Λ¯|⩽0.02, is compared with the theoretical values discussed recently in the literature.

  1. [Gold antirheumatic drug: desired and adverse effects of Au(I) and Au(III) [corrected] on the immune system.

    PubMed

    Griem, P; Gleichmann, E

    1996-01-01

    Three new findings are reviewed that help to understand the mechanisms of action of anti-rheumatic gold drugs, such as disodium aurothiomalate (Na2Au(I)TM): i) We found that Na2Au(I)TM selectively inhibits T-cell receptor-mediated antigen recognition by murine CD4+ T-cell hybridomas specific for antigenic peptides containing at least two cysteine residues. Presumably, Au(I) acts as a chelating agent forming linear complexes (Cys-Au(I)-Cys) which prevents correct antigen-processing and/or peptide recognition by the T-cell receptor, ii) We were able to show that Au(I) is oxidized to Au(III) in mononuclear phagocytes, such as macrophages. Because Au(III) rapidly oxidizes protein and itself is re-reduced to Au(I), this may introduce an Au(I)/Au(III) redox system into phagocytes which scavenges reactive oxygen species, such as hypochlorous acid (HOCl) and inactivates lysosomal enzymes, iii) Pretreatment with Au(III) of a model protein antigen, bovine ribonuclease A (RNase A), induced novel antigenic determinants recognized by CD4+ T lymphocytes. Analysis of the fine specificity of these "Au(III)-specific" T-cells revealed that they react to RNase peptides that are not presented to T-cells when the native protein, i.e., not treated with Au(III), is used as antigen. The T-cell recognition of these cryptic peptides did not require the presence of gold. This finding has important implications for understanding the pathogenesis of allergic and autoimmune responses induced by gold drugs. Taken together, our findings indicate that Au(I) and Au(III) each exert specific effects on several distinct functions of macrophages and the activation of T-cells. These effects may explain both the desired anti-inflammatory and the adverse effects of antirheumatic gold drugs. PMID:9036720

  2. RHIC Au beam in Run 2014

    SciTech Connect

    Zhang, S. Y.

    2014-09-15

    Au beam at the RHIC ramp in run 2014 is reviewed together with the run 2011 and run 2012. Observed bunch length and longitudinal emittance are compared with the IBS simulations. The IBS growth rate of the longitudinal emittance in run 2014 is similar to run 2011, and both are larger than run 2012. This is explained by the large transverse emittance at high intensity observed in run 2012, but not in run 2014. The big improvement of the AGS ramping in run 2014 might be related to this change. The importance of the injector intensity improvement in run 2014 is emphasized, which gives rise to the initial luminosity improvement of 50% in run 2014, compared with the previous Au-Au run 2011. In addition, a modified IBS model, which is calibrated using the RHIC Au runs from 9.8 GeV/n to 100 GeV/n, is presented and used in the study.

  3. Di-hadron correlations with identified leading hadrons in 200 GeV Au + Au and d + Au collisions at STAR

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Bai, X.; Bairathi, V.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, T.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, W.; Li, Z. M.; Li, Y.; Li, C.; Li, X.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Ma, R.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Peterson, A.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Y.; Sun, Z.; Sun, X. M.; Sun, X.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Tawfik, A.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, J. S.; Wang, F.; Wang, H.; Wang, G.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Wu; Xiao, Z. G.; Xie, W.; Xin, K.; Xu, H.; Xu, Z.; Xu, Q. H.; Xu, Y. F.; Xu, N.; Yang, S.; Yang, Y.; Yang, Q.; Yang, Y.; Yang, C.; Yang, Y.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, Y.; Zhang, Z.; Zhang, J. B.; Zhang, J.; Zhang, X. P.; Zhang, S.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.

    2015-12-01

    The STAR Collaboration presents for the first time two-dimensional di-hadron correlations with identified leading hadrons in 200 GeV central Au + Au and minimum-bias d + Au collisions to explore hadronization mechanisms in the quark gluon plasma. The enhancement of the jet-like yield for leading pions in Au + Au data with respect to the d + Au reference and the absence of such an enhancement for leading non-pions (protons and kaons) are discussed within the context of a quark recombination scenario. The correlated yield at large angles, specifically in the ridge region, is found to be significantly higher for leading non-pions than pions. The consistencies of the constituent quark scaling, azimuthal harmonic model and a mini-jet modification model description of the data are tested, providing further constraints on hadronization.

  4. Thermal stability of sputtered intermetallic Al-Au coatings

    SciTech Connect

    Moser, M.; Mayrhofer, P. H.; Ross, I. M.; Rainforth, W. M.

    2007-09-15

    Recently, the authors have shown that single-phase Al{sub 2}Au coatings, prepared by unbalanced magnetron sputtering, exhibit a dense columnar structure and highest hardness and indentation moduli of 8 and 144 GPa, respectively, within the Al-Au films investigated. This study focuses on the thermal stability of Al{sub 2}Au with respect to films containing more Al and Au having Al/Au at. % ratios of 4.32 and 1.85, respectively. Single-phase Al{sub 2}Au has the highest onset temperature for recovery of 475 deg. C and recrystallization of 575 deg. C. Upon annealing Au- and Al-rich films, their stresses deviate from the linear thermoelastic behavior at temperatures (T) above 200 and 450 deg. C, respectively, due to pores and metallic phases present. Metastable Au within the as-deposited Au-rich film is consumed by the growing intermetallic AlAu and AlAu{sub 2} phases at T{>=}450 deg. C, which themselves melt at {approx}625 deg. C. Due to nanometer scale segregations of Al, encapsulated by Al{sub 2}Au in Al-rich coatings, their melting point is reduced by {approx}85 deg. C to 575 deg. C. Dynamic thermal analyses up to 1100 deg. C in synthetic air reveal the single-phase Al{sub 2}Au films with a superior thermal stability and only negligible oxidation. At 750 deg. C, the mass gain is {approx}1.5 mg/cm{sup 2} after 50 h isothermal exposure. Based on the investigations, the authors can conclude that single-phase intermetallic Al{sub 2}Au films have a high potential for oxidation protection of sensitive materials.

  5. Jets and dijets in Au+Au and p+p collisions at RHIC

    SciTech Connect

    Hardtke, D.; STAR Collaboration

    2002-12-09

    Recent data from RHIC suggest novel nuclear effects in the production of high p{sub T} hadrons. We present results from the STAR detector on high p{sub T} angular correlations in Au+Au and p+p collisions at {radical}S = 200 GeV/c. These two-particle angular correlation measurements verify the presence of a partonic hard scattering and fragmentation component at high p{sub T} in both central and peripheral Au+Au collisions. When triggering on a leading hadron with p{sub T}>4 GeV, we observe a quantitative agreement between the jet cone properties in p+p and all centralities of Au+Au collisions. This quantitative agreement indicates that nearly all hadrons with p{sub T}>4 GeV/c come from jet fragmentation and that jet fragmentation properties are not substantially modified in Au+Au collisions. STAR has also measured the strength of back-to-back high p{sub T} charged hadron correlations, and observes a small suppression of the back-to-back correlation strength in peripheral collisions, and a nearly complete disappearance o f back-to-back correlations in central Au+Au events. These phenomena, together with the observed strong suppression of inclusive yields and large value of elliptic flow at high p{sub T}, are consistent with a model where high p{sub T} hadrons come from partons created near the surface of the collision region, and where partons that originate or propagate towards the center of the collision region are substantially slowed or completely absorbed.

  6. Au-Sn SLID Bonding: A Reliable HT Interconnect and Die Attach Technology

    NASA Astrophysics Data System (ADS)

    Tollefsen, Torleif André; Larsson, Andreas; Taklo, Maaike Margrete Visser; Neels, Antonia; Maeder, Xavier; Høydalsvik, Kristin; Breiby, Dag W.; Aasmundtveit, Knut

    2013-04-01

    Au-Sn solid-liquid interdiffusion (SLID) bonding is an established reliable high temperature (HT) die attach and interconnect technology. This article presents the life cycle of an optimized HT Au-Sn SLID bond, from fabrication, via thermal treatment, to mechanical rupture. The layered structure of a strong and uniform virgin bond was identified by X-ray diffraction to be Au/ζ (Au0.85Sn0.15)/Au. During HT exposure, it was transformed to Au/β (Au1.8Sn0.2)/Au. After HT exposure, the die shear strength was reduced by 50 pct, from 14 Pa to 70 MPa, which is still remarkably high. Fractographic studies revealed a change in fracture mode; it was changed from a combination of adhesive Au/Ni and cohesive SiC fracture to a cohesive β-phase fracture. Design rules for high quality Au-Sn SLID bonds are given.

  7. Do Methanethiol Adsorbates on the Au(111) Surface Dissociate?

    NASA Astrophysics Data System (ADS)

    Zhou, Jian-Ge; Hagelberg, Frank

    2006-07-01

    The interaction of methanethiol molecules CH3SH with the Au(111) surface is investigated, and it is found for the first time that the S-H bond remains intact when the methanethiol molecules are adsorbed on the regular Au(111) surface. However, it breaks if defects are present in the Au(111) surface. At low coverage, the fcc region is favored for S atom adsorption, but at saturated coverage the adsorption energies at various sites are almost isoenergetic. The presented calculations show that a methanethiol layer on the regular Au(111) surface does not dimerize.

  8. Flow and bose-einstein correlations in Au-Au collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Phobos Collaboration; Manly, Steven; Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Henderson, C.; Hofman, D.; Hollis, R. S.; Hołyinski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S. F.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    2003-03-01

    Argonne flow and Bose-Einstein correlations have been measured in Au-Au collisions at S=130 and 200 GeV using the PHOBOS detector at RHIC. The systematic dependencies of the flow signal on the transverse momentum, pseudorapidity, and centrality of the collision, as well as the beam energy are shown. In addition, results of a 3-dimensional analysis of two-pion correlations in the 200 GeV data are presented.

  9. Lateral spreading of Au contacts on InP

    NASA Technical Reports Server (NTRS)

    Fatemi, Navid S.; Weizer, Victor G.

    1990-01-01

    The contact spreading phenomenon observed when small area Au contacts on InP are annealed at temperatures above about 400 C was investigated. It was found that the rapid lateral expansion of the contact metallization which consumes large quantities of InP during growth is closely related to the third stage in the series of solid state reactions that occur between InP and Au, i.e., to the Au3In-to-Au9In4 transition. Detailed descriptions are presented of both the spreading process and the Au3In-to-Au9In4 transition along with arguments that the two processes are manifestations of the same basic phenomenon.

  10. Preparations for p-Au run in 2015

    SciTech Connect

    Liu, C.

    2014-12-31

    The p-Au particle collision is a unique category of collision runs. This is resulted from the different charge mass ratio of the proton and fully stripped Au ion (1 vs.79/197). The p-Au run requires a special acceleration ramp, and movement of a number of beam components as required by the beam trajectories. The DX magnets will be moved for the first time in the history of RHIC. In this note, the planning and preparations for p-Au run will be presented.

  11. Transverse-energy distributions at midrapidity in p +p, d +Au, and Au +Au collisions at √sNN =62.4-200 GeV and implications for particle-production models

    NASA Astrophysics Data System (ADS)

    Adler, S. S.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Jamel, A.; Alexander, J.; Aoki, K.; Aphecetche, L.; Armendariz, R.; Aronson, S. H.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Baldisseri, A.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Bathe, S.; Batsouli, S.; Baublis, V.; Bauer, F.; Bazilevsky, A.; Belikov, S.; Bennett, R.; Berdnikov, Y.; Bjorndal, M. T.; Boissevain, J. G.; Borel, H.; Boyle, K.; Brooks, M. L.; Brown, D. S.; Bruner, N.; Bucher, D.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Burward-Hoy, J. M.; Butsyk, S.; Camard, X.; Campbell, S.; Chai, J.-S.; Chand, P.; Chang, W. C.; Chernichenko, S.; Chi, C. Y.; Chiba, J.; Chiu, M.; Choi, I. J.; Choudhury, R. K.; Chujo, T.; Cianciolo, V.; Cleven, C. R.; Cobigo, Y.; Cole, B. A.; Comets, M. P.; Constantin, P.; Csanád, M.; Csörgő, T.; Cussonneau, J. P.; Dahms, T.; Das, K.; David, G.; Deák, F.; Delagrange, H.; Denisov, A.; D'Enterria, D.; Deshpande, A.; Desmond, E. J.; Devismes, A.; Dietzsch, O.; Dion, A.; Drachenberg, J. L.; Drapier, O.; Drees, A.; Dubey, A. K.; Durum, A.; Dutta, D.; Dzhordzhadze, V.; Efremenko, Y. V.; Egdemir, J.; Enokizono, A.; En'yo, H.; Espagnon, B.; Esumi, S.; Fields, D. E.; Finck, C.; Fleuret, F.; Fokin, S. L.; Forestier, B.; Fox, B. D.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fung, S.-Y.; Gadrat, S.; Gastineau, F.; Germain, M.; Glenn, A.; Gonin, M.; Gosset, J.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Hachiya, T.; Hadj Henni, A.; Haggerty, J. S.; Hagiwara, M. N.; Hamagaki, H.; Hansen, A. G.; Harada, H.; Hartouni, E. P.; Haruna, K.; Harvey, M.; Haslum, E.; Hasuko, K.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Heuser, J. M.; Hidas, P.; Hiejima, H.; Hill, J. C.; Hobbs, R.; Holmes, M.; Holzmann, W.; Homma, K.; Hong, B.; Hoover, A.; Horaguchi, T.; Hur, M. G.; Ichihara, T.; Iinuma, H.; Ikonnikov, V. V.; Imai, K.; Inaba, M.; Inuzuka, M.; Isenhower, D.; Isenhower, L.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Jacak, B. V.; Jia, J.; Jin, J.; Jinnouchi, O.; Johnson, B. M.; Johnson, S. C.; Joo, K. S.; Jouan, D.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kaneta, M.; Kang, J. H.; Katou, K.; Kawabata, T.; Kawagishi, T.; Kazantsev, A. V.; Kelly, S.; Khachaturov, B.; Khanzadeev, A.; Kikuchi, J.; Kim, D. J.; Kim, E.; Kim, E. J.; Kim, G.-B.; Kim, H. J.; Kim, Y.-S.; Kinney, E.; Kiss, Á.; Kistenev, E.; Kiyomichi, A.; Klein-Boesing, C.; Kobayashi, H.; Kochenda, L.; Kochetkov, V.; Kohara, R.; Komkov, B.; Konno, M.; Kotchetkov, D.; Kozlov, A.; Kroon, P. J.; Kuberg, C. H.; Kunde, G. J.; Kurihara, N.; Kurita, K.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lajoie, J. G.; Lebedev, A.; Leâ Bornec, Y.; Leckey, S.; Lee, D. M.; Lee, M. K.; Leitch, M. J.; Leite, M. A. L.; Li, X. H.; Lim, H.; Litvinenko, A.; Liu, M. X.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mao, Y.; Martinez, G.; Masui, H.; Matathias, F.; Matsumoto, T.; McCain, M. C.; McGaughey, P. L.; Miake, Y.; Miller, T. E.; Milov, A.; Mioduszewski, S.; Mishra, G. C.; Mitchell, J. T.; Mohanty, A. K.; Morrison, D. P.; Moss, J. M.; Moukhanova, T. V.; Mukhopadhyay, D.; Muniruzzaman, M.; Murata, J.; Nagamiya, S.; Nagata, Y.; Nagle, J. L.; Naglis, M.; Nakamura, T.; Newby, J.; Nguyen, M.; Norman, B. E.; Nyanin, A. S.; Nystrand, J.; O'Brien, E.; Ogilvie, C. A.; Ohnishi, H.; Ojha, I. D.; Okada, K.; Omiwade, O. O.; Oskarsson, A.; Otterlund, I.; Oyama, K.; Ozawa, K.; Pal, D.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, J.; Park, W. J.; Pate, S. F.; Pei, H.; Penev, V.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Pierson, A.; Pinkenburg, C.; Pisani, R. P.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Qualls, J. M.; Rak, J.; Ravinovich, I.; Read, K. F.; Reuter, M.; Reygers, K.; Riabov, V.; Riabov, Y.; Roche, G.; Romana, A.; Rosati, M.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Rykov, V. L.; Ryu, S. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakai, S.; Samsonov, V.; Sanfratello, L.; Santo, R.; Sarsour, M.; Sato, H. D.; Sato, S.; Sawada, S.; Schutz, Y.; Semenov, V.; Seto, R.; Sharma, D.; Shea, T. K.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shohjoh, T.; Shoji, K.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Sim, K. S.; Singh, C. P.; Singh, V.; Skutnik, S.; Smith, W. C.; Soldatov, A.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Staley, F.; Stankus, P. W.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Sugitate, T.; Suire, C.; Sullivan, J. P.; Sziklai, J.; Tabaru, T.; Takagi, S.; Takagui, E. M.; Taketani, A.; Tanaka, K. H.; Tanaka, Y.; Tanida, K.; Tannenbaum, M. J.; Taranenko, A.; Tarján, P.; Thomas, T. L.; Togawa, M.; Tojo, J.; Torii, H.; Towell, R. S.; Tram, V.-N.

    2014-04-01

    Measurements of the midrapidity transverse-energy distribution, dET/dη, are presented for p +p, d +Au, and Au +Au collisions at √sNN =200 GeV and additionally for Au +Au collisions at √sNN =62.4 and 130 GeV. The dET/dη distributions are first compared with the number of nucleon participants Npart, number of binary collisions Ncoll, and number of constituent-quark participants Nqp calculated from a Glauber model based on the nuclear geometry. For Au +Au, /Npart increases with Npart, while /Nqp is approximately constant for all three energies. This indicates that the two-component ansatz, dET/dη ∝(1-x)Npart/2+xNcoll, which was used to represent ET distributions, is simply a proxy for Nqp, and that the Ncoll term does not represent a hard-scattering component in ET distributions. The dET/dη distributions of Au +Au and d +Au are then calculated from the measured p +p ET distribution using two models that both reproduce the Au +Au data. However, while the number-of-constituent-quark-participant model agrees well with the d +Au data, the additive-quark model does not.

  12. Magnetic susceptibilities of liquid Cr-Au, Mn-Au and Fe-Au alloys

    SciTech Connect

    Ohno, S.; Shimakura, H.; Tahara, S.; Okada, T.

    2015-08-17

    The magnetic susceptibility of liquid Cr-Au, Mn-Au, Fe-Au and Cu-Au alloys was investigated as a function of temperature and composition. Liquid Cr{sub 1-c}Au{sub c} with 0.5 ≤ c and Mn{sub 1-c}Au{sub c} with 0.3≤c obeyed the Curie-Weiss law with regard to their dependence of χ on temperature. The magnetic susceptibilities of liquid Fe-Au alloys also exhibited Curie-Weiss behavior with a reasonable value for the effective number of Bohr magneton. On the Au-rich side, the composition dependence of χ for liquid TM-Au (TM=Cr, Mn, Fe) alloys increased rapidly with increasing TM content, respectively. Additionally, the composition dependences of χ for liquid Cr-Au, Mn-Au, and Fe-Au alloys had maxima at compositions of 50 at% Cr, 70 at% Mn, and 85 at% Fe, respectively. We compared the composition dependences of χ{sub 3d} due to 3d electrons for liquid binary TM-M (M=Au, Al, Si, Sb), and investigated the relationship between χ{sub 3d} and E{sub F} in liquid binary TM-M alloys at a composition of 50 at% TM.

  13. Electrochemistry of Au(II) and Au(III) pincer complexes: determination of the Au(II)-Au(II) bond energy.

    PubMed

    Dann, Thomas; Roşca, Dragoş-Adrian; Wright, Joseph A; Wildgoose, Gregory G; Bochmann, Manfred

    2013-10-01

    The bond energy of the unsupported Au-Au bond in the Au(ii) dimer [(C(∧)N(∧)C)Au]2 and the difference between Au(III)-OH and Au(III)-H bond enthalpies have been determined experimentally by electrochemical methods, with Au-OH and Au-H complexes showing unexpected differences in their reduction pathways, supported by DFT modelling. PMID:24051607

  14. Azimuthal anisotropy of ϕ meson in U+U and Au+Au collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Bairathi, Vipul

    2016-01-01

    The measurements of the azimuthal anisotropy of φ meson in the U+U and Au+Au collisions at the Relativistic Heavy-Ion Collider (RHIC) are reported. The centrality dependence of the Fourier coefficients v2, v3, v4 and v5 is presented for φ meson at midrapidity (|ƞ| < 1.0), in U+U and Au+Au collisions at -√8NN = 193 and 200 GeV, respectively. The ƞ-sub event plane method is used with a n gap of 0.1 to suppress the non-flow effects. A strong centrality dependence is observed for the φ meson elliptic flow (v2), whereas no clear centrality dependence is observed for v3, v4 and v5. Ratios of the Fourier coefficients, v3/v2 and v4/v22 as a function of transverse momentum (pT) are also presented. A systematic comparison of the Fourier coefficients for the two systems U+U and Au+Au is discussed.

  15. Microstructural evolution of eutectic Au-Sn solder joints

    SciTech Connect

    Song, Ho Geon

    2002-05-31

    Current trends toward miniaturization and the use of lead(Pb)-free solder in electronic packaging present new problems in the reliability of solder joints. This study was performed in order to understand the microstructure and microstructural evolution of small volumes of nominally eutectic Au-Sn solder joints (80Au-20Sn by weight), which gives insight into properties and reliability.

  16. Jet-hadron correlations in √[s(NN)]=200  GeV p+p and central Au+Au collisions.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-03-28

    Azimuthal angular correlations of charged hadrons with respect to the axis of a reconstructed (trigger) jet in Au+Au and p+p collisions at √[s(NN)]=200  GeV in STAR are presented. The trigger jet population in Au+Au collisions is biased toward jets that have not interacted with the medium, allowing easier matching of jet energies between Au+Au and p+p collisions while enhancing medium effects on the recoil jet. The associated hadron yield of the recoil jet is significantly suppressed at high transverse momentum (pTassoc) and enhanced at low pTassoc in 0%-20% central Au+Au collisions compared to p+p collisions, which is indicative of medium-induced parton energy loss in ultrarelativistic heavy-ion collisions. PMID:24724645

  17. Magnetoresistance of Au films

    SciTech Connect

    Zhang, D. L.; Song, X. H.; Zhang, X; Zhang, Xiaoguang

    2014-01-01

    Measurement of the magnetoresistance (MR) of Au films as a function of temperature and film thickness reveals a strong dependence on grain size distribution and clear violation of the Kohler s rule. Using a model of random resistor network, we show that this result can be explained if the MR arises entirely from inhomogeneity due to grain boundary scattering and thermal activation of grain boundary atoms.

  18. Magnetoresistance of Au films

    DOE PAGESBeta

    Zhang, D. L.; Song, X. H.; Zhang, X.; Zhang, Xiaoguang

    2014-12-10

    Measurement of the magnetoresistance (MR) of Au films as a function of temperature and film thickness reveals a strong dependence on grain size distribution and clear violation of the Kohler s rule. Using a model of random resistor network, we show that this result can be explained if the MR arises entirely from inhomogeneity due to grain boundary scattering and thermal activation of grain boundary atoms.

  19. Charged particle multiplicity fluctuations in Au+Au collisions at \\sqrt{s_{NN}} = 200\\, {\\rm GeV}

    NASA Astrophysics Data System (ADS)

    Wozniak, Krzysztof; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J. L.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wolfs, F. L. H.; Wosiek, B.; Wuosmaa, A. H.; Wyslouch, B.

    2004-08-01

    This paper presents the first PHOBOS results on charged particle multiplicity fluctuations measured for Au+Au collisions at the highest RHIC energy within a wide pseudorapidity range of |eegr| < 3. The dependence on collision geometry is removed in the analysis by using the normalized difference between the number of particles in separate eegr bins. We compare our data to HIJING model predictions.

  20. Cu-Au, Ag-Au, Cu-Ag, and Ni-Au intermetallics: First-principles study of temperature-composition phase diagrams and structures

    NASA Astrophysics Data System (ADS)

    Ozoliņš, V.; Wolverton, C.; Zunger, Alex

    1998-03-01

    The classic metallurgical systems-noble-metal alloys-that have formed the benchmark for various alloy theories are revisited. First-principles fully relaxed general-potential linearized augmented plane-wave (LAPW) total energies of a few ordered structures are used as input to a mixed-space cluster expansion calculation to study the phase stability, thermodynamic properties, and bond lengths in Cu-Au, Ag-Au, Cu-Ag, and Ni-Au alloys. (i) Our theoretical calculations correctly reproduce the tendencies of Ag-Au and Cu-Au to form compounds and Ni-Au and Cu-Ag to phase separate at T=0 K. (ii) Of all possible structures, Cu3Au (L12) and CuAu (L10) are found to be the most stable low-temperature phases of Cu1-xAux with transition temperatures of 530 K and 660 K, respectively, compared to the experimental values 663 K and ~670 K. The significant improvement over previous first-principles studies is attributed to the more accurate treatment of atomic relaxations in the present work. (iii) LAPW formation enthalpies demonstrate that L12, the commonly assumed stable phase of CuAu3, is not the ground state for Au-rich alloys, but rather that ordered (100) superlattices are stabilized. (iv) We extract the nonconfigurational (e.g., vibrational) entropies of formation and obtain large values for the size-mismatched systems: 0.48 kB/atom in Ni0.5Au0.5 (T=1100 K), 0.37 kB/atom in Cu0.141Ag0.859 (T=1052 K), and 0.16 kB/atom in Cu0.5Au0.5 (T=800 K). (v) Using 8 atom/cell special quasirandom structures we study the bond lengths in disordered Cu-Au and Ni-Au alloys and obtain good qualitative agreement with recent extended x-ray-absorption fine-structure measurements.

  1. Ultrafast charge carrier dynamics in Au/semiconductor nanoheterostructures

    NASA Astrophysics Data System (ADS)

    Lambright, Scott

    The charge carrier dynamics in several Au/semiconductor core/shell heterostructures were examined. Firstly, Au/CdS core/shell nanocomposites were synthesized in a four step procedure culminating in a cation exchange performed on the shell. Previous studies of the ultrafast carrier dynamics in Au/CdS nanocomposites with epitaxial boundary regions reported the suppression of plasmon character in transient absorption spectra accompanied by broadband photoinduced absorption. The coupling of electron wavefunctions with lattice defects at the boundary of the two domains has been blamed for these phenomena. In the current study, transmission electron micrographs of Au/CdS synthesized using cation exchange showed no evidence of strain on the lattice of either component, while femtosecond transient absorption data show the retention of bleach regions attributed to CdS's 1S(e)-1S3/2(h) transition and Au's plasmon resonance. Accelerated rates of bleach recovery for both excitations ( tauexiton ≈ 300 ps, tauplasmon ≈ .7 ps) indicated that the interaction of Au and CdS domains leads to faster relaxation to their respective photoexcitations when compared to relaxation times in isolated Au and CdS nanoparticles. It was believed that the Au/CdS boundary was non-epitaxial in the presented core/shell nanocomposites. Secondly, these non-epitaxial Au/CdS core/shells were subsequently used to demonstrate near-field energy transfer from 5 nm diameter Au cores to CdS-encapsulated CdSe quantum dots. To this end, Au/CdS and CdSe/CdS nanocrystals were embedded in semiconductor-matrix-encapsulated-nanocrystal-arrays (SMENA) together. The encapsulation of both domains in the high band-gap semiconductor CdS was a means to suppress charge transfer between the two nanoparticles. The fluorescence intensity in these films was enhanced 6-fold in some cases as a result of the presence of Au domains. It was also demonstrated that the fluorescence enhancement was independent of the potential

  2. Beam Energy Scan a Case for the Chiral Magnetic Effect in Au-Au Collisions

    SciTech Connect

    Longacre, R.

    2014-01-05

    The Chiral Magnetic Effect (CME) is predicted for Au-Au collisions at RHIC. However, many backgrounds can give signals that make the measurement hard to interpret. The STAR experiment has made measurements at different collisions energy ranging from √(sNN)=7.7 GeV to 62.4 GeV. In the analysis that is presented we show that the CME turns on with energy and is not present in central collisions where the induced magnetic is small.

  3. Surface morphology and optical properties of porphyrin/Au and Au/porphyrin/Au systems

    NASA Astrophysics Data System (ADS)

    Kalachyova, Yevgeniya; Lyutakov, Oleksiy; Solovyev, Andrey; Slepička, Petr; Švorčík, Vaclav

    2013-12-01

    Porphyrin/Au and Au/porphyrin/Au systems were prepared by vacuum evaporation and vacuum sputtering onto glass substrate. The surface morphology of as-prepared systems and those subjected to annealing at 160°C was studied by optical microscopy, atomic force microscopy, and scanning electron microscopy techniques. Absorption and luminescence spectra of as-prepared and annealed samples were measured. Annealing leads to disintegration of the initially continuous gold layer and formation of gold nanoclusters. An amplification of Soret band magnitude was observed on the Au/meso-tetraphenyl porphyrin (TPP) system in comparison with mere TPP. Additional enhancement of luminescence was observed after the sample annealing. In the case of sandwich Au/porphyrin/Au structure, suppression of one of the two porphyrins' luminescence maxima and sufficient enhancement of the second one were observed.

  4. Hierarchical organization of Au nanoparticles in a poly(vinyl carbazole) matrix for hybrid electronic devices

    NASA Astrophysics Data System (ADS)

    Lee, Sangkyu; Yoon, Seon-Mi; Shin, Hyeon-Jin; Joo, Won-Jae; Yi, Dong Kee; Choi, Jae-Young; Amarnath, Chellachamy A.; Paik, Ungyu

    2008-02-01

    We report a novel one-step method for the preparation of hierarchically patterned Au nanoparticles in a conducting polymer matrix by controlling the interface properties between Au nanoparticles and the conducting polymer matrix. The terminal group of capping molecules for the Au nanoparticles was modified to change the interface properties, not to change the size of the Au nanoparticles which affects their intrinsic properties. By modulating the interface properties, it is possible to construct Au nanoparticle-conducting polymer composites with two different structures: one presents a triple layer in which the conducting polymer layer is sandwiched between Au nanoparticle layers at the top and bottom; the other exhibits a form like a raisin cake in which Au nanoparticles are homogeneously organized in the conducting polymer matrix. High-resolution transmission electron microscopy was used to study the morphology and patterning of Au nanoparticles in the conducting polymer matrix.

  5. Biogenic synthesis of Ag, Au and bimetallic Au/Ag alloy nanoparticles using aqueous extract of mahogany (Swietenia mahogani JACQ.) leaves.

    PubMed

    Mondal, Samiran; Roy, Nayan; Laskar, Rajibul A; Sk, Ismail; Basu, Saswati; Mandal, Debabrata; Begum, Naznin Ara

    2011-02-01

    In this paper, we have demonstrated for the first time, the superb efficiency of aqueous extract of dried leaves of mahogany (Swietenia mahogani JACQ.) in the rapid synthesis of stable monometallic Au and Ag nanoparticles and also Au/Ag bimetallic alloy nanoparticles having spectacular morphologies. Our method was clean, nontoxic and environment friendly. When exposed to aqueous mahogany leaf extract, competitive reduction of Au(III) and Ag(I) ions present simultaneously in same solution leads to the production of bimetallic Au/Ag alloy nanoparticles. UV-visible spectroscopy was used to monitor the kinetics of nanoparticles formation. UV-visible spectroscopic data and TEM images revealed the formation of bimetallic Au/Ag alloy nanoparticles. Mahogany leaf extract contains various polyhydroxy limonoids which are responsible for the reduction of Au(III) and Ag(I) ions leading to the formation and stabilization of Au and Ag nanopaticles. PMID:21030220

  6. Nanoporous Au: an unsupported pure gold catalyst?

    SciTech Connect

    Wittstock, A; Neumann, B; Schaefer, A; Dumbuya, K; Kuebel, C; Biener, M; Zielasek, V; Steinrueck, H; Gottfried, M; Biener, J; Hamza, A; B?umer, M

    2008-09-04

    The unique properties of gold especially in low temperature CO oxidation have been ascribed to a combination of various effects. In particular, particle sizes below a few nm and specific particle-support interactions have been shown to play important roles. On the contrary, recent reports revealed that monolithic nanoporous gold (npAu) prepared by leaching a less noble metal, such as Ag, out of the corresponding alloy can also exhibit remarkably high catalytic activity for CO oxidation, even though no support is present. Therefore, it was claimed to be a pure and unsupported gold catalyst. We investigated npAu with respect to its morphology, surface composition and catalytic properties. In particular, we studied the reaction kinetics for low temperature CO oxidation in detail taking mass transport limitation due to the porous structure of the material into account. Our results reveal that Ag, even if removed almost completely from the bulk, segregates to the surface resulting in surface concentrations of up to 10 at%. Our data suggest that this Ag plays a significant role in activation of molecular oxygen. Therefore, npAu should be considered as a bimetallic catalyst rather than a pure Au catalyst.

  7. Enantiospecific adsorption of cysteine on a chiral Au34 cluster

    NASA Astrophysics Data System (ADS)

    Pelayo, José de Jesús; Valencia, Israel; Díaz, Gabriela; López-Lozano, Xóchitl; Garzón, Ignacio L.

    2015-12-01

    The interaction of biological molecules like chiral amino acids with chiral metal clusters is becoming an interesting and active field of research because of its potential impact in, for example, chiral molecular recognition phenomena. In particular, the enantiospecific adsorption (EA) of cysteine (Cys) on a chiral Au55 cluster was theoretically predicted a few years ago. In this work, we present theoretical results, based on density functional theory, of the EA of non-zwitterionic cysteine interacting with the C3-Au34 chiral cluster, which has been experimentally detected in gas phase, using trapped ion electron diffraction. Our results show that, indeed, the adsorption energy of the amino acid depends on which enantiomers participate in the formation Cys-Au34 chiral complex. EA was obtained in the adsorption modes where both the thiol, and the thiol-amino functional groups of Cys are adsorbed on low-coordinated sites of the metal cluster surface. Similarly to what was obtained for the Cys-Au55 chiral complex, in the present work, it is found that the EA is originated from the different strength and location of the bond between the COOH functional group and surface Au atoms of the Au34 chiral cluster. Calculations of the vibrational spectrum for the different Cys-Au34 diastereomeric complexes predict the existence of a vibro-enantiospecific effect, indicating that the vibrational frequencies of the adsorbed amino acid depend on its handedness.

  8. Atomic and electronic structures of Si(1 1 1)-(√3 x √3)R30°-Au and (6 × 6)-Au surfaces.

    PubMed

    Patterson, C H

    2015-12-01

    Si(1 1 1)-Au surfaces with around one monolayer of Au exhibit many ordered structures and structures containing disordered domain walls. Hybrid density functional theory (DFT) calculations presented here reveal the origin of these complex structures and tendency to form domain walls. The conjugate honeycomb chain trimer (CHCT) structure of the [Formula: see text]-Au phase contains Si atoms with non-bonding surface states which can bind Au atoms in pairs in interstices of the CHCT structure and make this surface metallic. Si adatoms adsorbed on the [Formula: see text]-Au surface induce a gapped surface through interaction with the non-bonding states. Adsorption of extra Au atoms in interstitial sites of the [Formula: see text]-Au surface is stabilized by interaction with the non-bonding orbitals and leads to higher coverage ordered structures including the [Formula: see text]-Au phase. Extra Au atoms bound in interstitial sites of the [Formula: see text]-Au surface result in top layer Si atoms with an SiAu4 butterfly wing configuration. The structure of a [Formula: see text]-Au phase, whose in-plane top atomic layer positions were previously determined by an electron holography technique (Grozea et al 1998 Surf. Sci. 418 32), is calculated using total energy minimization. The Patterson function for this structure is calculated and is in good agreement with data from an in-plane x-ray diffraction study (Dornisch et al 1991 Phys. Rev. B 44 11221). Filled and empty state scanning tunneling microscopy (STM) images are calculated for domain walls and the [Formula: see text]-Au structure. The [Formula: see text]-Au phase is 2D chiral and this is evident in computed and actual STM images. [Formula: see text]-Au and domain wall structures contain the SiAu4 motif with a butterfly wing shape. Chemical bonding within the Si-Au top layers of the [Formula: see text]-Au and [Formula: see text]-Au surfaces is analyzed and an explanation for the SiAu4 motif structure is given. PMID

  9. Energy Dependence of Particle Multiplicities in Central Au+Au Collisions

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Corbo, J.; Decowski, M. P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Henderson, C.; Hicks, D.; Hofman, D.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A.; Mülmenstädt, J.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Rafelski, M.; Rbeiz, M.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    2002-01-01

    We present the first measurement of the pseudorapidity density of primary charged particles in Au+Au collisions at (sNN) = 200 GeV. For the 6% most central collisions, we obtain dNch/dη\\|\\|η\\|<1 = 650+/-35(syst). Compared to collisions at (sNN) = 130 GeV, the highest energy studied previously, an increase by a factor of 1.14+/-0.05 at 90% confidence level, is found. The energy dependence of the pseudorapidity density is discussed in comparison with data from proton-induced collisions and theoretical predictions.

  10. Dependence of SERS enhancement on the chemical composition and structure of Ag/Au hybrid nanoparticles.

    PubMed

    Chaffin, Elise; O'Connor, Ryan T; Barr, James; Huang, Xiaohua; Wang, Yongmei

    2016-08-01

    Noble metal nanoparticles (NPs) such as silver (Ag) and gold (Au) have unique plasmonic properties that give rise to surface enhanced Raman scattering (SERS). Generally, Ag NPs have much stronger plasmonic properties and, hence, provide stronger SERS signals than Au NPs. However, Ag NPs lack the chemical stability and biocompatibility of comparable Au NPs and typically exhibit the most intense plasmonic resonance at wavelengths much shorter than the optimal spectral region for many biomedical applications. To overcome these issues, various experimental efforts have been devoted to the synthesis of Ag/Au hybrid NPs for the purpose of SERS detections. However, a complete understanding on how the SERS enhancement depends on the chemical composition and structure of these nanoparticles has not been achieved. In this study, Mie theory and the discrete dipole approximation have been used to calculate the plasmonic spectra and near-field electromagnetic enhancements of Ag/Au hybrid NPs. In particular, we discuss how the electromagnetic enhancement depends on the mole fraction of Au in Ag/Au alloy NPs and how one may use extinction spectra to distinguish between Ag/Au alloyed NPs and Ag-Au core-shell NPs. We also show that for incident laser wavelengths between ∼410 nm and 520 nm, Ag/Au alloyed NPs provide better electromagnetic enhancement than pure Ag, pure Au, or Ag-Au core-shell structured NPs. Finally, we show that silica-core Ag/Au alloy shelled NPs provide even better performance than pure Ag/Au alloy or pure solid Ag and pure solid Au NPs. The theoretical results presented will be beneficial to the experimental efforts in optimizing the design of Ag/Au hybrid NPs for SERS-based detection methods. PMID:27497571

  11. Dependence of SERS enhancement on the chemical composition and structure of Ag/Au hybrid nanoparticles

    NASA Astrophysics Data System (ADS)

    Chaffin, Elise; O'Connor, Ryan T.; Barr, James; Huang, Xiaohua; Wang, Yongmei

    2016-08-01

    Noble metal nanoparticles (NPs) such as silver (Ag) and gold (Au) have unique plasmonic properties that give rise to surface enhanced Raman scattering (SERS). Generally, Ag NPs have much stronger plasmonic properties and, hence, provide stronger SERS signals than Au NPs. However, Ag NPs lack the chemical stability and biocompatibility of comparable Au NPs and typically exhibit the most intense plasmonic resonance at wavelengths much shorter than the optimal spectral region for many biomedical applications. To overcome these issues, various experimental efforts have been devoted to the synthesis of Ag/Au hybrid NPs for the purpose of SERS detections. However, a complete understanding on how the SERS enhancement depends on the chemical composition and structure of these nanoparticles has not been achieved. In this study, Mie theory and the discrete dipole approximation have been used to calculate the plasmonic spectra and near-field electromagnetic enhancements of Ag/Au hybrid NPs. In particular, we discuss how the electromagnetic enhancement depends on the mole fraction of Au in Ag/Au alloy NPs and how one may use extinction spectra to distinguish between Ag/Au alloyed NPs and Ag-Au core-shell NPs. We also show that for incident laser wavelengths between ˜410 nm and 520 nm, Ag/Au alloyed NPs provide better electromagnetic enhancement than pure Ag, pure Au, or Ag-Au core-shell structured NPs. Finally, we show that silica-core Ag/Au alloy shelled NPs provide even better performance than pure Ag/Au alloy or pure solid Ag and pure solid Au NPs. The theoretical results presented will be beneficial to the experimental efforts in optimizing the design of Ag/Au hybrid NPs for SERS-based detection methods.

  12. J/ψ suppression at forward rapidity in Au + Au collisions at sNN=39 and 62.4 GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Ta'ani, H.; Alexander, J.; Angerami, A.; Aoki, K.; Apadula, N.; Aramaki, Y.; Asano, H.; Aschenauer, E. C.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bannier, B.; Barish, K. N.; Bassalleck, B.; Bathe, S.; Baublis, V.; Baumgart, S.; Bazilevsky, A.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Bing, X.; Blau, D. S.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Butsyk, S.; Campbell, S.; Castera, P.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Csanád, M.; Csörgő, T.; Dairaku, S.; Datta, A.; Daugherity, M. S.; David, G.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Ding, L.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; D'Orazio, L.; Edwards, S.; Efremenko, Y. V.; Engelmore, T.; Enokizono, A.; Esumi, S.; Eyser, K. O.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M., Jr.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fusayasu, T.; Gainey, K.; Gal, C.; Garishvili, A.; Garishvili, I.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Guo, L.; Gustafsson, H.-Å.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hanks, J.; Hashimoto, K.; Haslum, E.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Horaguchi, T.; Hori, Y.; Huang, S.; Ichihara, T.; Iinuma, H.; Ikeda, Y.; Imrek, J.; Inaba, M.; Iordanova, A.; Isenhower, D.; Issah, M.; Ivanischev, D.; Jacak, B. V.; Javani, M.; Jia, J.; Jiang, X.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Kamin, J.; Kaneti, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, C.; Kim, D. J.; Kim, E.-J.; Kim, H. J.; Kim, K.-B.; Kim, Y.-J.; Kim, Y. K.; Kinney, E.; Kiss, Á.; Kistenev, E.; Klatsky, J.; Kleinjan, D.; Kline, P.; Komatsu, Y.; Komkov, B.; Koster, J.; Kotchetkov, D.; Kotov, D.; Král, A.; Krizek, F.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, B.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Lee, S. R.; Leitch, M. J.; Leite, M. A. L.; Leitgab, M.; Lewis, B.; Lim, S. H.; Linden Levy, L. A.; Liu, M. X.; Love, B.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; Masumoto, S.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyachi, Y.; Miyasaka, S.; Mohanty, A. K.; Moon, H. J.; Morrison, D. P.; Motschwiller, S.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Nagae, T.; Nagamiya, S.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Nederlof, A.; Nihashi, M.; Nouicer, R.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Okada, K.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, B. H.; Park, I. H.; Park, S. K.; Pate, S. F.; Patel, L.; Pei, H.; Peng, J.-C.; Pereira, H.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Qu, H.; Rak, J.; Ravinovich, I.; Read, K. F.; Reynolds, R.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Samsonov, V.; Sano, M.; Sarsour, M.; Sawada, S.; Sedgwick, K.; Seidl, R.; Sen, A.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Soumya, M.; Sourikova, I. V.; Stankus, P. W.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sun, J.; Sziklai, J.; Takagui, E. M.; Takahara, A.; Taketani, A.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Themann, H.; Todoroki, T.; Tomášek, L.; Tomášek, M.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Tsuji, T.; Vale, C.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Vossen, A.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Wei, R.; White, S. N.; Winter, D.; Wolin, S.; Woody, C. L.; Wysocki, M.; Yamaguchi, Y. L.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; You, Z.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.

    2012-12-01

    We present measurements of the J/ψ invariant yields in sNN=39 and 62.4 GeV Au + Au collisions at forward rapidity (1.2<|y|<2.2). Invariant yields are presented as a function of both collision centrality and transverse momentum. Nuclear modifications are obtained for central relative to peripheral Au + Au collisions (RCP) and for various centrality selections in Au + Au relative to scaled p + p cross sections obtained from other measurements (RAA). The observed suppression patterns at 39 and 62.4 GeV are quite similar to those previously measured at 200 GeV. This similar suppression presents a challenge to theoretical models that contain various competing mechanisms with different energy dependencies, some of which cause suppression and others enhancement.

  13. A comparative study of the Au + H2, Au+ + H2, and Au- + H2 systems: Potential energy surfaces and dynamics of reactive collisions

    NASA Astrophysics Data System (ADS)

    Dorta-Urra, Anaís; Zanchet, Alexandre; Roncero, Octavio; Aguado, Alfredo

    2015-04-01

    In order to study the Au- + H2 collision, a new global potential energy surface (PES) describing the ground electronic state of AuH 2- system is developed and compared with the PESs of the neutral [Zanchet et al., J. Chem. Phys. 132, 034301 (2010)] and cationic systems [Anaís et al., J. Chem. Phys. 135, 091102 (2011)]. We found that Au- - H2 presents a H-Au-H insertion minimum attributed to the stabilization of the LUMO 3b2 orbital, which can be considered as the preamble of the chemisorption well appearing in larger gold clusters. While the LUMO orbital is stabilized, the HOMO 6a1 is destabilized, creating a barrier at the geometry where the energy orbitals' curves are crossing. In the anion, this HOMO is doubly occupied, while in the neutral system is half-filled and completely empty in the cation, explaining the gradual disappearance of the well and the barrier as the number of electrons decreases. The cation presents a well in the entrance channel partially explained by electrostatic interactions. The three systems' reactions are highly endothermic, by 1.66, 2.79, and 3.23 eV for AuH, AuH+, and AuH- products, respectively. The reaction dynamics is studied using quasi-classical trajectory method for the three systems. The one corresponding to the anionic system is new in this work. Collision energies between 1.00 and 8.00 eV, measured for the cation, are in good agreement with the simulated cross section for the AuH+. It was also found that the total fragmentation, in three atoms, competes becoming dominant at sufficiently high energy. Here, we study the competition between the two different reaction pathways for the anionic, cationic, and neutral species, explaining the differences using a simple model based on the topology of the potential energy surfaces.

  14. Ge-Au eutectic bonding of Ge {100} single crystals

    NASA Astrophysics Data System (ADS)

    Knowlton, W. B.; Itoh, K. M.; Beeman, J. W.; Emes, J. H.; Loretto, D.; Haller, E. E.

    1993-11-01

    We present preliminary results on the eutectic bonding between two {100} Ge single crystal surfaces using thin films of Au ranging from 900Å/surface to 300Å/surface and Pd (10% the thickness of Au). Following bonding, plan view optical microscopy (OM) of the cleaved interface of samples with Au thicknesses ≤ 500Å/surface show a eutectic morphology more conducive to phonon transmission through the bond interface. High resolution transmission electron microscopy (HRTEM) cross sectional interface studies of a 300Å/surface Au sample show <100> epitaxial growth of Ge. In sections of the bond, lattice continuity of the Ge is apparent through the interface. TEM studies also reveal <110> heteroepitaxial growth of Au with a Au-Ge lattice mismatch of less than 2%. Eutectic bonds with 200Å/surface Au have been attained with characterization pending. An optical polishing technique for Ge has been optimized to insure intimate contact between the Ge surfaces prior to bonding. Interferometry analysis of the optically polished Ge surface shows that surface height fluctuations lie within ±150Å across an interval of 1mm. Characterization of phonon transmission through the interface is discussed with respect to low temperature detection of ballistic phonons.

  15. Gold chloride clusters with Au(III) and Au(I) probed by FT-ICR mass spectrometry and MP2 theory.

    PubMed

    Lemke, Kono H

    2014-05-01

    Microsolvated clusters of gold chloride are probed by electrospray ionization mass spectrometry (ESI-MS) and scalar relativistic electronic structure calculations. Electrospray ionization of aqueous AuCl3 leads to mononuclear clusters of types [AuCl2](+)(H2O)n (n = 0-4), [AuOHCl](+)(H2O)n (n = 0-1) and [AuCl2](+)(HCl)2(H2O)n (n = 0-4). In addition, strong ion signals due to dinuclear [Au2Cl5-xOHx](+)(H2O)n (x = 0-1) are present in ESI mass spectra of aqueous AuCl3, with the abundance of individual dinuclear species controlled by the concentration-dependent variation of the precursor complexes [AuCl2-xOHx](+)(H2O)n and AuCl3. Equilibrium structures, energies and thermodynamic properties of mono- and dinuclear gold clusters have been predicted using MP2 and CCSD(T) theory, and these data have been applied to examine the influence of microsolvation on cluster stability. Specifically, results from CCSD(T) calculations indicate that non-covalently bound ion-neutral complexes Au(+)(Cl2)(H2O)n, with formal Au(I), are the dominant forms of mononuclear gold with n = 0-2, while higher hydrates (n > 2) are covalently bound [AuCl2](+)(H2O)n complexes in which gold exists as Au(III). MP2 calculations show that the lowest energy structure of dinuclear gold is an ion-molecule cluster [Au2Cl(Cl2)2](+) consisting of a single-bridged digold-chloronium ion bound end-on to two dichlorine ligands, with two higher energy isomers, single-bridged [Au2Cl3(Cl2)](+) and double-bridged [Au2Cl5](+) clusters. Finally, AuAu interactions in the singly-bridged clusters [Au2Cl(Cl2)2](+)(H2O)n and [Au2Cl3(Cl2)](+)(H2O)n are examined employing a wide range of computational tools, including natural bond order (NBO) analysis and localized orbital locator (LOL) profiles. PMID:24643288

  16. Gold-Adatom-Mediated Bonding in Self-Assembled Short-Chain Alkanethiolate Species on the Au(111) Surface

    SciTech Connect

    Maksymovych, P.; Sorescu, D.C.; Yates, J.T., Jr.

    2006-10-06

    Microscopic evidence for Au-adatom-induced self-assembly of alkanethiolate species on the Au(111) surface is presented. Based on STM measurements and density-functional theory calculations, a new model for the low-coverage self-assembled monolayer of alkanethiolate on the Au(111) surface is developed, which involves the adsorbate complexes incorporating Au adatoms. It is also concluded that the Au(111) herringbone reconstruction is lifted by the alkanethiolate self-assembly because the reconstructed surface layer provides reactive Au adatoms that drive self-assembly.

  17. Crystal structures and magnetic properties of CsAu4Si2 and CeAu2Si2

    SciTech Connect

    Sefat, A.; Palasyuk, A.; Bud'ko, S.; Corbett, J.; Canfield, P.

    2007-12-03

    Single crystals of CeAu{sub 4}Si{sub 2} and CeAu{sub 2}Si{sub 2} have been grown out of ternary fluxes rich in Au, and the former, also by sintering the stoichiometric composition at 750 C. The single-crystal X-ray refinement result for CeAu{sub 4}Si{sub 2} is orthorhombic, Cmmm (No. 65, Z=2), different from a tetragonal result found from an X-ray powder diffraction refinement [H. Nakashima, et al., J. Alloys Compds. 424 (2006) 7]. For CeAu{sub 2}Si{sub 2}, this is the first report of the stoichiometric crystalline phase, in the known tetragonal I4/mmm structure. The anisotropic field- and temperature-dependent magnetizations, as well as specific heat and resistivity data are compared. Although both compounds have related structural packing, they present unique magnetic features. CeAu{sub 2}Si{sub 2} is a typical antiferromagnet with T{sub N} = 8.8(1) K and CeAu{sub 4}Si{sub 2} features a ferromagnetic component below T{sub c}=3.3(1) K. Both phases have effective moments close in value to that of free Ce{sup 3+}.

  18. Gold surfaces and nanoparticles are protected by Au(0)-thiyl species and are destroyed when Au(I)-thiolates form.

    PubMed

    Reimers, Jeffrey R; Ford, Michael J; Halder, Arnab; Ulstrup, Jens; Hush, Noel S

    2016-03-15

    The synthetic chemistry and spectroscopy of sulfur-protected gold surfaces and nanoparticles is analyzed, indicating that the electronic structure of the interface is Au(0)-thiyl, with Au(I)-thiolates identified as high-energy excited surface states. Density-functional theory indicates that it is the noble character of gold and nanoparticle surfaces that destabilizes Au(I)-thiolates. Bonding results from large van der Waals forces, influenced by covalent bonding induced through s-d hybridization and charge polarization effects that perturbatively mix in some Au(I)-thiolate character. A simple method for quantifying these contributions is presented, revealing that a driving force for nanoparticle growth is nobleization, minimizing Au(I)-thiolate involvement. Predictions that Brust-Schiffrin reactions involve thiolate anion intermediates are verified spectroscopically, establishing a key feature needed to understand nanoparticle growth. Mixing of preprepared Au(I) and thiolate reactants always produces Au(I)-thiolate thin films or compounds rather than monolayers. Smooth links to O, Se, Te, C, and N linker chemistry are established. PMID:26929334

  19. Global transverse energy distributions in Si+Al, Au at 14.6 A GeV/ c and Au+Au at 11.6 A GeV/ c

    NASA Astrophysics Data System (ADS)

    Ahle, L.; Akiba, Y.; Beavis, D.; Britt, H. C.; Budick, B.; Chasman, C.; Chen, Z.; Chi, C. Y.; Chu, Y. Y.; Cianciolo, V.; Cole, B. A.; Costales, J. B.; Crawford, H. J.; Cumming, J. B.; Debbe, R.; Engelage, J.; Fung, S. Y.; Gonin, M.; Gushue, S.; Hamagaki, H.; Hansen, O.; Hayano, R. S.; Hayashi, S.; Homma, S.; Kaneko, H.; Kang, J.; Kaufman, S.; Kehoe, W. L.; Kurita, K.; LeVine, M. J.; Miake, Y.; Morrison, D. P.; Moskowitz, B.; Nagamiya, S.; Namboodiri, M. N.; Nayak, T. K.; Olness, J.; Remsberg, L. P.; Rothschild, P.; Sangster, T. C.; Seto, R.; Shigaki, K.; Soltz, R.; Steadman, S. G.; Stephans, G. S. F.; Sung, T.; Tannenbaum, M. J.; Thomas, J.; Tonse, S.; Ueno, S.; van Dijk, J. H.; Videbaek, F.; Vossnack, O.; Wang, F. Q.; Wang, Y.; Wegner, H. E.; Woodruff, D. S.; Wu, Y. D.; Yagi, K.; Yang, X.; Zachary, D.; Zajc, W. A.; E-802 Collaboration

    1994-07-01

    Measurements of the global transverse energy distributions dσ/ dET and dET/ dη using the new AGS beam of 197Au at 11.6 A GeV/ c on a Au target, as well as a beam of 28Si at 14.6 A GeV/ c on Al and Au targets, are presented for a leadglass detector with acceptance 1.3 ≤ η ≤ 2.4 and 0 ≤ φ < 2 π. The dσ/ dET spectra are observed to have different shapes for the different systems and simple energy rescaling does not account for the projectile dependence. The Au+Au dσ/ dET spectrum is satisfactorily constructed from the upper edge of Si+Au by the geometric Wounded Projectile Nucleon Model after applying a correction for the beam energy.

  20. Au20: A Tetrahedral Cluster

    SciTech Connect

    Li, Jun; Li, Xi; Zhai, Hua Jin; Wang, Lai S.

    2003-02-07

    Photoelectron spectroscopy revealed that a 20 atom gold cluster has an extremely large energy gap, which is even greater than that of C60, and an electron affinity comparable with that of C60. This observation suggests that the Au20 cluster must be extremely stable and chemically inert. Using relativistic density functional calculations, we found that Au20 possesses a remarkable tetrahedral structure, which is a fragment of the bulk face-centered cubic lattice of gold with a small structural relaxation. Au20 is thus a true cluster molecule, while at the same time it is exactly part of the bulk, but with very different properties. The tetrahedral Au20 may possess interesting catalytic properties and may be synthesized in bulk quantity or assembled on non-interacting surfaces.

  1. Gold-gold bonding: the key to stabilizing the 19-electron ternary phases LnAuSb (Ln = La-Nd and Sm).

    PubMed

    Seibel, Elizabeth M; Schoop, Leslie M; Xie, Weiwei; Gibson, Quinn D; Webb, James B; Fuccillo, Michael K; Krizan, Jason W; Cava, Robert J

    2015-01-28

    We report a new family of ternary 111 hexagonal LnAuSb (Ln = La-Nd, Sm) compounds that, with a 19 valence electron count, has one extra electron compared to all other known LnAuZ compounds. LaAuSb, CeAuSb, PrAuSb, NdAuSb, and SmAuSb crystallize in the YPtAs-type structure, and have a doubled unit cell compared to other LnAuZ phases as a result of the buckling of the Au-Sb honeycomb layers to create interlayer Au-Au dimers. The dimers accommodate the one excess electron per Au and thus these new phases can be considered Ln2(3+)(Au-Au)(0)Sb2(3-). Band structure, density of states, and crystal orbital calculations confirm this picture, which results in a nearly complete band gap between full and empty electronic states and stable compounds; we can thus present a structural stability phase diagram for the LnAuZ (Z = Ge, As, Sn, Sb, Pb, Bi) family of phases. Those calculations also show that LaAuSb has a bulk Dirac cone below the Fermi level. The YPtAs-type LnAuSb family reported here is an example of the uniqueness of gold chemistry applied to a rigidly closed shell system in an unconventional way. PMID:25543990

  2. Azimuthally sensitive hanbury brown-twiss interferometry in Au + Au collisions sqrt S sub NN = 200 GeV

    SciTech Connect

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj, S.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Carroll, J.; Castillo, J.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Gronstal, S.; Grosnick, D.; Guertin, S.M.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang, L.S.; Hughes, E.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaplan, M.; Keane, D.; Khodyrev, V.Yu.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, V.I.; Kravtsov, P.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; Kunde, G.J.; Kunz, C.L.; Kutuev, R.Kh.; Kuznetsov, A.A.; Lamont, M.A.C.; et al.

    2004-06-30

    We present the results of a systematic study of the shape of the pion distribution in coordinate space at freeze-out in Au+Au collisions at RHIC using two-pion Hanbury Brown-Twiss (HBT) interferometry. Oscillations of the extracted HBT radii vs. emission angle indicate sources elongated perpendicular to the reaction plane. The results indicate that the pressure and expansion time of the collision system are not sufficient to completely quench its initial shape.

  3. Λ Λ Correlation Function in Au +Au Collisions at √{sN N }=200 GeV

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Contin, G.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Kosarzewski, L. K.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Olvitt, D. L.; Page, B. S.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Simko, M.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, J. L.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2015-01-01

    We present Λ Λ correlation measurements in heavy-ion collisions for Au +Au collisions at √{sN N }=200 GeV using the STAR experiment at the Relativistic Heavy-Ion Collider. The Lednický-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the Λ Λ correlation function and interaction parameters for dihyperon searches are discussed.

  4. Au transport in catalyst coarsening and Si nanowire formation.

    PubMed

    Kim, B J; Tersoff, J; Kodambaka, S; Jang, Ja-Soon; Stach, E A; Ross, F M

    2014-08-13

    The motion of Au between AuSi liquid eutectic droplets, both before and during vapor-liquid-solid growth, is important in controlling tapering and diameter uniformity in Si nanowires. We measure the kinetics of coarsening of AuSi droplets on Si(001) and Si(111), quantifying the size evolution of droplets during annealing in ultrahigh vacuum using in situ transmission electron microscopy. For individual droplets, we show that coarsening kinetics are modified when disilane or oxygen is added: coarsening rates increase in the presence of disilane but decrease in oxygen. Matching droplet size measurements on Si(001) with coarsening models confirms that Au transport is driven by capillary forces and that the kinetic coefficients depend on the gas environment present. We suggest that the gas effects are qualitatively similar whether transport is attachment limited or diffusion limited. These results provide insight into manipulating nanowire morphologies for advanced device fabrication. PMID:25040757

  5. Presentation by the scientific and technical commission on the analysis of the events relating to the unexpected ice storm of 5 to 9 January. Presentation a la commission scientifique et technique chargee d'analyser les evenements relatifs (a) la tempete de verglas survenue du 5 au 9 janvier 1998

    SciTech Connect

    Not Available

    1998-01-01

    The first part of this report contains three presentations in French by directors of Hydro-Quebec regarding the utility's actions during the January 1998 ice storm and initiatives to reinforce and maintain the power network to avoid ice storm problems in the future. The second part is in a question and answer format and covers the utility's response to ice storm threats in the following areas: Climate (forecasting of ice storm periods, line design criteria, impact of climatic changes and El Nino, ice data interpretation and measurement, research); structural aspects, including failures of components, towers, and lines; electrical aspects, including consolidation of the transmission system, power system security, burying of installations, conductor de-icing, strategic lines, and manpower use; economic aspects (network improvement, reliability, continuity and maintenance expenditures, interconnections, internal communications, service enhancement programs, work force reduction, strategic plans); and the management of emergency measures, including planning, service restoration priorities, human and material resources management, coordination, communications, and risk analysis.

  6. Strange Baryon Resonance Production in {radical}(s{sub NN})=200 GeV p+p and Au+Au Collisions

    SciTech Connect

    Abelev, B. I.; Bielcik, J.; Bielcikova, J.; Caines, H.; Catu, O.; Chikanian, A.; Du, F.; Finch, E.; Harris, J. W.; Heinz, M.; Lamont, M. A. C.; Lin, G.; Majka, R.; Nattrass, C.; Salur, S.; Sandweiss, J.; Smirnov, N.; Witt, R.; Aggarwal, M. M.; Bhati, A. K.

    2006-09-29

    We report the measurements of {sigma}(1385) and {lambda}(1520) production in p+p and Au+Au collisions at {radical}(s{sub NN})=200 GeV from the STAR Collaboration. The yields and the p{sub T} spectra are presented and discussed in terms of chemical and thermal freeze-out conditions and compared to model predictions. Thermal and microscopic models do not adequately describe the yields of all the resonances produced in central Au+Au collisions. Our results indicate that there may be a time span between chemical and thermal freeze-out during which elastic hadronic interactions occur.

  7. Unimolecular rectifiers: Present status

    NASA Astrophysics Data System (ADS)

    Metzger, Robert M.

    2006-07-01

    Many experimental issues presented here must be resolved before we can really understand unimolecular rectification. Nevertheless, at the University of Alabama six unimolecular rectifiers have been studied (Fig. 1, 1- 6). Langmuir-Blodgett (LB) or Langmuir-Schaefer (LS) monolayer films of these molecules show asymmetric electrical conductivity between Au and Al electrodes. When the films are very compact (LS of 4, LB of 5), and if there is finite intramolecular charge transfer (ICT, or intervalence transfer, IVT), then the electrical behavior persists for many cycles of measurement.

  8. Systematic studies of the centrality dependence of soft photon production in Au + Au collision with PHENIX

    NASA Astrophysics Data System (ADS)

    Bannier, Benjamin

    2014-11-01

    Since the earliest days of Heavy Ion Physics thermal soft photon radiation emitted during the reaction had been theorized as a smoking gun signal for formation of a quark-gluon plasma and as a tool to characterize its properties. In recent years the existence of excess photon radiation in heavy ion collisions over the expectation from initial hard interactions has been confirmed at both RHIC and LHC energies by PHENIX and ALICE respectively. There the radiation has been found to exhibit elliptic flow v2 well above what can currently be reconciled with a picture of early emission from a plasma phase. During the 2007 and 2010 Au + Au runs PHENIX has measured a high purity sample of soft photons down to pT > 0.4 GeV / c using an external conversion method. We present recent systematic studies by PHENIX from that sample on the centrality dependence of the soft photon yield, and elliptic and triangular flow v2 and v3 in Au + Au collisions which fill in the experimental picture and enable discrimination of competing soft photon production scenarios.

  9. Photoionization of Au+ ions and developments in the synthesis of the metallofullerene Au@C60

    NASA Astrophysics Data System (ADS)

    Bogolub, Kyren; Macaluso, David; Mueller, Allison; Johnson, Andrea; Müller, Alfred; Schippers, Stefan; Hellhund, Jonas; Borovik, Alexander; Anders, Andre; Aguilar, Alex; Kilcoyne, A. L. David

    2014-05-01

    Single photoionization of Au+ ions was investigated via the merged-beams technique at AMO Beamline 10.0.1.2 of the Advanced Light Source at Lawrence Berkeley National Laboratory. The relative single photoionization yield was measured as a function of photon energy in the 45 eV to 120 eV energy range. These measurements were made in preparation for future photoionization studies of the endohedral metallofullerene Au@C60, the production of which was also investigated. In proof-of-principle measurements a mass-resolved beam of Au@C60+was produced with a primary ion beam current in the single picoamp range without optimization of the ion source or synthesis parameters. Plans are presented for improved metallofullere production yield to be used in photoionization measurements of the endohedral fullerene ions in conjunction with the continuing study of pure Au. We would like to acknowledge the generous sharing of equipment vital to this work by Andre Anders, the Plasma Applications group leader at the Advanced Light Source, LBNL.

  10. Interfacial nanodroplets guided construction of hierarchical Au, Au-Pt, and Au-Pd particles as excellent catalysts

    PubMed Central

    Ma, Aijing; Xu, Jie; Zhang, Xuehua; Zhang, Bin; Wang, Dayang; Xu, Haolan

    2014-01-01

    Interfacial nanodroplets were grafted to the surfaces of self-sacrificed template particles in a galvanic reaction system to assist the construction of 3D Au porous structures. The interfacial nanodroplets were formed via direct adsorption of surfactant-free emulsions onto the particle surfaces. The interfacial nanodroplets discretely distributed at the template particle surfaces and served as soft templates to guide the formation of porous Au structures. The self-variation of footprint sizes of interfacial nanodroplets during Au growth gave rise to a hierarchical pore size distribution of the obtained Au porous particles. This strategy could be easily extended to synthesize bimetal porous particles such as Au-Pt and Au-Pd. The obtained porous Au, Au-Pt, and Au-Pd particles showed excellent catalytic activity in catalytic reduction of 4-nitrophenol. PMID:24797697

  11. Interfacial nanodroplets guided construction of hierarchical Au, Au-Pt, and Au-Pd particles as excellent catalysts.

    PubMed

    Ma, Aijing; Xu, Jie; Zhang, Xuehua; Zhang, Bin; Wang, Dayang; Xu, Haolan

    2014-01-01

    Interfacial nanodroplets were grafted to the surfaces of self-sacrificed template particles in a galvanic reaction system to assist the construction of 3D Au porous structures. The interfacial nanodroplets were formed via direct adsorption of surfactant-free emulsions onto the particle surfaces. The interfacial nanodroplets discretely distributed at the template particle surfaces and served as soft templates to guide the formation of porous Au structures. The self-variation of footprint sizes of interfacial nanodroplets during Au growth gave rise to a hierarchical pore size distribution of the obtained Au porous particles. This strategy could be easily extended to synthesize bimetal porous particles such as Au-Pt and Au-Pd. The obtained porous Au, Au-Pt, and Au-Pd particles showed excellent catalytic activity in catalytic reduction of 4-nitrophenol. PMID:24797697

  12. Presentation by the scientific and technical commission on the analysis of the events relating to the unexpected ice storm of 5 to 9 January; Presentation a la commission scientifique et technique chargee d`analyser les evenements relatifs (a) la tempete de verglas survenue du 5 au 9 janvier 1998

    SciTech Connect

    1998-12-31

    The first part of this report contains three presentations in French by directors of Hydro-Quebec regarding the utility`s actions during the January 1998 ice storm and initiatives to reinforce and maintain the power network to avoid ice storm problems in the future. The second part is in a question and answer format and covers the utility`s response to ice storm threats in the following areas: Climate (forecasting of ice storm periods, line design criteria, impact of climatic changes and El Nino, ice data interpretation and measurement, research); structural aspects, including failures of components, towers, and lines; electrical aspects, including consolidation of the transmission system, power system security, burying of installations, conductor de-icing, strategic lines, and manpower use; economic aspects (network improvement, reliability, continuity and maintenance expenditures, interconnections, internal communications, service enhancement programs, work force reduction, strategic plans); and the management of emergency measures, including planning, service restoration priorities, human and material resources management, coordination, communications, and risk analysis.

  13. Symmetry energy from elliptic flow in 197Au + 197Au

    NASA Astrophysics Data System (ADS)

    Russotto, P.; Wu, P. Z.; Zoric, M.; Chartier, M.; Leifels, Y.; Lemmon, R. C.; Li, Q.; Łukasik, J.; Pagano, A.; Pawłowski, P.; Trautmann, W.

    2011-03-01

    The elliptic-flow ratio of neutrons with respect to protons or light complex particles in reactions of neutron-rich systems at relativistic energies is proposed as an observable sensitive to the strength of the symmetry term in the equation of state at supra-normal densities. The results obtained from the existing FOPI/LAND data for 197Au + 197Au collisions at 400 MeV/nucleon in comparison with the UrQMD model favor a moderately soft symmetry term with a density dependence of the potential term proportional to (ρ /ρ0) γ with γ = 0.9 ± 0.4.

  14. Spin Polarization and Quantum Spins in Au Nanoparticles

    PubMed Central

    Li, Chi-Yen; Karna, Sunil K.; Wang, Chin-Wei; Li, Wen-Hsien

    2013-01-01

    The present study focuses on investigating the magnetic properties and the critical particle size for developing sizable spontaneous magnetic moment of bare Au nanoparticles. Seven sets of bare Au nanoparticle assemblies, with diameters from 3.5 to 17.5 nm, were fabricated with the gas condensation method. Line profiles of the X-ray diffraction peaks were used to determine the mean particle diameters and size distributions of the nanoparticle assemblies. The magnetization curves M(Ha) reveal Langevin field profiles. Magnetic hysteresis was clearly revealed in the low field regime even at 300 K. Contributions to the magnetization from different size particles in the nanoparticle assemblies were considered when analyzing the M(Ha) curves. The results show that the maximum particle moment will appear in 2.4 nm Au particles. A similar result of the maximum saturation magnetization appearing in 2.3 nm Au particles is also concluded through analysis of the dependency of the saturation magnetization MP on particle size. The MP(d) curve departs significantly from the 1/d dependence, but can be described by a log-normal function. Magnetization can be barely detected for Au particles larger than 27 nm. Magnetic field induced Zeeman magnetization from the quantum confined Kubo gap opening appears in Au nanoparticles smaller than 9.5 nm in diameter. PMID:23989607

  15. Hohlraum Te Inferred from Au L-Shell Emission

    NASA Astrophysics Data System (ADS)

    Regan, S. P.; Epstein, R.; Meyerhofer, D. D.; Sangster, T. C.; May, M. J.; Schneider, M. B.; Barrios, M. A.; Moody, J. D.; Baker, K. L.; Berzak Hopkins, L.; Brown, G. V.; Callahan, D.; Doeppner, T.; Fournier, K. B.; Hinkel, D. E.; Jones, O. S.; Kauffman, R.; Khan, S.; Kilkenny, J. D.; Landen, O. L.; Liedahl, D. A.; Nagel, S. R.; Ross, J. S.; Smalyuk, V. A.

    2014-10-01

    Laser-ablation plasmas created at the inner wall of the hohlraum (Au bubble) and at the laser entrance hole (LEH) radiate L-shell emission from Ne-like to Co-like charge states of Au. A 1-D spatially resolved and time-integrated spectrum in the 6- to 16-keV range with E/d E = 100 to 300 is recorded along the axis of the hohlraum. The Au L-shell spectral line shapes of the 2p3 / 2 - 3 s , 2p3 / 2 - 3d5 / 2 , and 2p1 / 2 - 3d3 / 2 transitions are analyzed using an atomic physics code to infer the Te of the radiating plasma. Preliminary results indicate the Au LEH plasma of a near-vacuum hohlraum has an inferred Te of 5 to 6 keV, while a gas-filled hohlraum has a significantly lower Te. A comparison of the Au L-shell spectra and the Te sensitivity will be presented, along with the plan to measure the L-shell emission from the Au bubble. This material is based upon work supported by the Department Of Energy National Nuclear Security Administration under Award Number DE-NA0001944. Part of this work was performed under the auspices of the U.S. Department of Energy by LLNL under Contract DE-AC52-07NA27344.

  16. Synthesis of hybrid CdS-Au colloidal nanostructures.

    PubMed

    Saunders, Aaron E; Popov, Inna; Banin, Uri

    2006-12-21

    We explore the growth mechanism of gold nanocrystals onto preformed cadmium sulfide nanorods to form hybrid metal nanocrystal/semiconductor nanorod colloids. By manipulating the growth conditions, it is possible to obtain nanostructures exhibiting Au nanocrystal growth at only one nanorod tip, at both tips, or at multiple locations along the nanorod surface. Under anaerobic conditions, Au growth occurs only at one tip of the nanorods, producing asymmetric structures. In contrast, the presence of oxygen and trace amounts of water during the reaction promotes etching of the nanorod surface, providing additional sites for metal deposition. Three growth stages are observed when Au growth is performed under air: (1) Au nanocrystal formation at both nanorod tips, (2) growth onto defect sites on the nanorod surface, and finally (3) a ripening process in which one nanocrystal tip grows at the expense of the other particles present on the nanorod. Analysis of the hybrid nanostructures by high-resolution TEM shows that there is no preferred orientation between the Au nanocrystal and the CdS nanorod, indicating that growth is nonepitaxial. The optical signatures of the nanocrystals and the nanorods (i.e., the surface plasmon and first exciton transition peaks, respectively) are spectrally distinct, allowing the different stages of the growth process to be easily monitored. The initial CdS nanorods exhibit band gap and trap state emission, both of which are quenched during Au growth. PMID:17165989

  17. The Influence of Interstitial Ga and Interfacial Au (sub 2)P (sub 3) on the Electrical and Metallurgical Behavior of Au-Contacted III-V Semiconductors

    NASA Technical Reports Server (NTRS)

    Weizer, Victor G.; Fatemi, Navid S.

    1991-01-01

    The introduction of a very small amount of Ga into Au contact metallization on InP is shown to have a significant effect on both the metallurgical and electrical behavior of that contact system. Ga atoms in the interstices of the Au lattice are shown to be effective in preventing the solid state reactions that normally take place between Au and InP during contact sintering. In addition to suppressing the metallurgical interaction, the presence of small amounts of Ga is shown to cause an order of magnitude reduction in the specific contact resistivity. Evidence is presented that the reactions of GaP and GaAs with Au contacts are also drastically affected by the presence of Ga. The sintering behavior of the Au-GaP and the Au-GaAs systems (as contrasted with that of the Au-InP system) is explained as due to the presence of interstitial Ga in the contact metallization. Finally the large, two-to-three order of magnitude drop in the contact resistance that occurs in the Au-InP system upon sintering at 400 degrees Centigrade is shown to be a result of the formation of an Au (sub 2) P (sub 3) layer at the metal-semiconductor interface. Contact resistivities in the 10 (sup -6) ohm square centimeter range are obtained for as-deposited Au on InP when a thin (20 Angstrom) layer of Au (sub 2) P (sub 3) is introduced between the InP and the Au contacts.

  18. Charge transport in single Au / alkanedithiol / Au junctions: coordination geometries and conformational degrees of freedom.

    PubMed

    Li, Chen; Pobelov, Ilya; Wandlowski, Thomas; Bagrets, Alexei; Arnold, Andreas; Evers, Ferdinand

    2008-01-01

    Recent STM molecular break-junction experiments have revealed multiple series of peaks in the conductance histograms of alkanedithiols. To resolve a current controversy, we present here an in-depth study of charge transport properties of Au|alkanedithiol|Au junctions. Conductance histograms extracted from our STM measurements unambiguously confirm features showing more than one set of junction configurations. On the basis of quantum chemistry calculations, we propose that certain combinations of different sulfur-gold couplings and trans/gauche conformations act as the driving agents. The present study may have implications for experimental methodology: whenever conductances of different junction conformations are not statistically independent, the conductance histogram technique can exhibit a single series only, even though a much larger abundance of microscopic realizations exists. PMID:18076172

  19. Dynamical evolution of interplanetary magnetic fields and flows between 0.3 AU and 8.5 AU - Entrainment

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Schwenn, R.; Rosenbauer, H.

    1983-01-01

    An analysis is presented of the radial evolution of interplanetary flows and associated magnetic fields between 0.3 AU and 8.5 AU using data from Helios 1 and B Voyager 1, respectively. The results indicate that in moving to 8 AU the largest corotating streams swept up the slower flows and shocks into a relatively thin region in which they coalesced to form a single large-amplitude compression. As a result of this process, referred to as entrainment, memory of the sources and flow configurations near the sun is lost, while small-scale features are erased as the flows move outward and energy is transferred from small scales to large scales.It is concluded that in the outer solar system the structure of the solar wind may be dominated by large scale pressure waves separated by several AU, while beyond several AU most of the compression waves are no longer driven by streams, and the compression waves expand freely. At large distances (greater than 25 AU) these compression waves will have interacted extensively with one another producing another state of the solar wind, with fewer large-scale nonuniformities and more small-scale nonuniformities.

  20. Heterojunction metal-oxide-metal Au-Fe{sub 3}O{sub 4}-Au single nanowire device for spintronics

    SciTech Connect

    Reddy, K. M. Punnoose, Alex; Hanna, Charles; Padture, Nitin P.

    2015-05-07

    In this report, we present the synthesis of heterojunction magnetite nanowires in alumina template and describe magnetic and electrical properties from a single nanowire device for spintronics applications. Heterojunction Au-Fe-Au nanowire arrays were electrodeposited in porous aluminum oxide templates, and an extensive and controlled heat treatment process converted Fe segment to nanocrystalline cubic magnetite phase with well-defined Au-Fe{sub 3}O{sub 4} interfaces as confirmed by the transmission electron microscopy. Magnetic measurements revealed Verwey transition shoulder around 120 K and a room temperature coercive field of 90 Oe. Current–voltage (I-V) characteristics of a single Au-Fe{sub 3}O{sub 4}-Au nanowire have exhibited Ohmic behavior. Anomalous positive magnetoresistance of about 0.5% is observed on a single nanowire, which is attributed to the high spin polarization in nanowire device with pure Fe{sub 3}O{sub 4} phase and nanocontact barrier. This work demonstrates the ability to preserve the pristine Fe{sub 3}O{sub 4} and well defined electrode contact metal (Au)–magnetite interface, which helps in attaining high spin polarized current.

  1. Mn2Au: body-centered-tetragonal bimetallic antiferromagnets grown by molecular beam epitaxy.

    PubMed

    Wu, Han-Chun; Liao, Zhi-Min; Sofin, R G Sumesh; Feng, Gen; Ma, Xiu-Mei; Shick, Alexander B; Mryasov, Oleg N; Shvets, Igor V

    2012-12-11

    Mn(2)Au, a layered bimetal, is successfully grown using molecular beam epitaxy (MBE). The experiments and theoretical calculations presented suggest that Mn(2)Au film is antiferromagnetic with a very low critical temperature. The antiferromagnetic nature is demonstrated by measuring the exchange-bias effect of Mn(2)Au/Fe bilayers. This study establishes a primary basis for further research of this new antiferromagnet in spin-electronic device applications. PMID:22996352

  2. Hollow octahedral and cuboctahedral nanocrystals of ternary Pt-Ni-Au alloys

    NASA Astrophysics Data System (ADS)

    Shviro, Meital; Polani, Shlomi; Zitoun, David

    2015-08-01

    Hollow particles of Pt-Ni-Au alloys have been prepared through a two-step reaction with the synthesis of NiPt octahedral and cuboctahedral templates followed by a galvanic replacement reaction by Au(iii). Metal etching presents an efficient method to yield hollow particles and investigate the Au diffusion in the metallic Pt-Ni framework through macroscopic (X-ray diffraction and SQUID magnetic measurement) and microscopic (HRTEM and STEM) measurements. The hollow particles retain the shape of the original nanocrystals. The nucleation of Au is found to be induced preferentially on the tip of the polyhedral nanocrystals while the etching of Ni starts from the facets leaving hollow octahedral particles consisting of 2 nm thick edges. In the presence of oleylamine, the Au tip grows and yields a heterogeneous dimer hollow-NiPt/Au. Without oleylamine, the Au nucleation is followed by Au diffusion in the Ni/Pt framework to yield a hollow single crystal Pt-Ni-Au alloy. The Pt-Ni-Au alloyed particles display a superparamagnetic behavior at room temperature.

  3. Microstructural Evolution and Mechanical Properties in (AuSn)eut-Cu Interconnections

    NASA Astrophysics Data System (ADS)

    Dong, Hongqun; Vuorinen, Vesa; Laurila, Tomi; Paulasto-Kröckel, Mervi

    2016-06-01

    The interfacial reactions between the widely employed solder Au-20wt.%Sn and the common contact metallizations (e.g. Ni, Cu and Pt) are normally complex and not well determined. In order to identify the proper contactor for Au-20wt.%Sn solder, the present study focuses on (1) rationalizing the interfacial reaction mechanisms of Au-20wt.%Sn|Cu as well as (2) measuring the mechanical properties of individual intermetallics formed at the interface. The evolution of interfacial reaction products were rationalized by using the experimental results in combination with the calculated Au-Cu-Sn phase diagram information. It was found that the growth of the AuCu interfacial intermetallic layer was diffusion-controlled. The diffusion path of Au-20wt.%Sn|Cu at 150°C was proposed. The hardness and indentation modulus of the interfacial reaction products were measured using nanoindentation tests. The results revealed a significant influence of the Cu solubility on the mechanical properties of (Au,Cu)Sn and (Au,Cu)5Sn, i.e. their hardness and contact modulus increased with the increase in the amount of Cu. Furthermore, results obtained here for the Au-20wt.%Sn|Cu joints were compared to those from Au-20wt.%Sn|Ni in order to assess the similarities and differences between these widely used interconnection metallization systems.

  4. Hollow octahedral and cuboctahedral nanocrystals of ternary Pt-Ni-Au alloys.

    PubMed

    Shviro, Meital; Polani, Shlomi; Zitoun, David

    2015-08-28

    Hollow particles of Pt-Ni-Au alloys have been prepared through a two-step reaction with the synthesis of NiPt octahedral and cuboctahedral templates followed by a galvanic replacement reaction by Au(iii). Metal etching presents an efficient method to yield hollow particles and investigate the Au diffusion in the metallic Pt-Ni framework through macroscopic (X-ray diffraction and SQUID magnetic measurement) and microscopic (HRTEM and STEM) measurements. The hollow particles retain the shape of the original nanocrystals. The nucleation of Au is found to be induced preferentially on the tip of the polyhedral nanocrystals while the etching of Ni starts from the facets leaving hollow octahedral particles consisting of 2 nm thick edges. In the presence of oleylamine, the Au tip grows and yields a heterogeneous dimer hollow-NiPt/Au. Without oleylamine, the Au nucleation is followed by Au diffusion in the Ni/Pt framework to yield a hollow single crystal Pt-Ni-Au alloy. The Pt-Ni-Au alloyed particles display a superparamagnetic behavior at room temperature. PMID:26202729

  5. Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces

    SciTech Connect

    Knowlton, W.B. |

    1995-07-01

    This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 {angstrom} Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 {angstrom}, 500 {angstrom}, and 300 {angstrom} per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 {angstrom}/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 {angstrom}/side appear to correspond with the phonon transmission study.

  6. Enantiospecific adsorption of cysteine on a chiral Au34 cluster

    NASA Astrophysics Data System (ADS)

    de Jesús Pelayo, José; Valencia, Israel; Díaz, Gabriela; López-Lozano, Xóchitl; Garzón, Ignacio L.

    2015-12-01

    The interaction of biological molecules like chiral amino acids with chiral metal clusters is becoming an interesting and active field of research because of its potential impact in, for example, chiral molecular recognition phenomena. In particular, the enantiospecific adsorption (EA) of cysteine (Cys) on a chiral Au55 cluster was theoretically predicted a few years ago. In this work, we present theoretical results, based on density functional theory, of the EA of non-zwitterionic cysteine interacting with the C3-Au34 chiral cluster, which has been experimentally detected in gas phase, using trapped ion electron diffraction. Our results show that, indeed, the adsorption energy of the amino acid depends on which enantiomers participate in the formation Cys-Au34 chiral complex. EA was obtained in the adsorption modes where both the thiol, and the thiol-amino functional groups of Cys are adsorbed on low-coordinated sites of the metal cluster surface. Similarly to what was obtained for the Cys-Au55 chiral complex, in the present work, it is found that the EA is originated from the different strength and location of the bond between the COOH functional group and surface Au atoms of the Au34 chiral cluster. Calculations of the vibrational spectrum for the different Cys-Au34 diastereomeric complexes predict the existence of a vibro-enantiospecific effect, indicating that the vibrational frequencies of the adsorbed amino acid depend on its handedness. Contribution to the Topical Issue "Atomic Cluster Collisions (7th International Symposium)", edited by G. Delgado Barrio, A. Solov'Yov, P. Villarreal, R. Prosmiti.

  7. The characteristics of Au:VO2 nanocomposite thin film for photo-electricity applications

    NASA Astrophysics Data System (ADS)

    Zhu, Yabin; Na, Jie; He, Fan; Zhou, Yueliang

    2013-08-01

    Au nanoparticles have been fabricated on normal glass substrates using nanosphere lithography (NSL) method. Vanadium dioxide has been deposited on Au/glass by reactive radio frequency (rf) magnetron sputtering. The structure and composition were determined by X-ray diffraction and X-ray photoelectron spectroscope. Electrical and optical properties of bare VO2 and Au:VO2 nanocomposite thin films were measured. Typical hysteresis behavior and sharp phase transition were observed. Nanopartical Au could effectively reduce the transition temperature to 40 °C. The transmittance spectrum for both Au:VO2 nanocomposite thin film shows high transmittance under transition temperature and low transmittance above transition temperature. The characteristics present the Au:VO2 nanocomposite thin film can be used for applications, such as “smart window” or “laser protector”.

  8. Evidence for an equilibrium epitaxial complexion at the Au-MgAl2O4 interface

    NASA Astrophysics Data System (ADS)

    Majdi, Tahereh; Zhu, Guo-zhen; Carvalho, Jessica; Jarvis, Victoria; Meinander, Kristoffer; Britten, James F.; Botton, Gianluigi; Preston, John S.

    2015-12-01

    Evidence for the existence of an equilibrium epitaxial complexion at the Au-MgAl2O4 interface has been observed. The growth of crystalline MgAl2O4 nanostructures, from a previously stable substrate in the presence of an Au overlayer and heat, is associated with this complexion. Prior to the nanostructures' self-assembly, Au nanoparticles crystalize, then reorient to align with the MgAl2O4 substrate. The presented results contradict earlier conclusions based solely on SEM studies of the final assembled nanostructures. Those results suggested that the MgAl2O4 grown pedestal and associated Au nanoparticle atop were both gold.

  9. Pion-kaon femtoscopy in Au+Au collisions at STAR

    NASA Astrophysics Data System (ADS)

    Poniatowska, Katarzyna; STAR Collaboration

    2015-05-01

    In non-identical particle correlations, e.g. pion-kaon femtoscopy, one can obtain information about source size and asymmetry in emission processes of pions and kaons. Such asymmetry give us knowledge of which type of particles is emitted first/second and/or from which region of the source. The studies of non-identical particle femtoscopy for Beam Energy Scan energies give us the opportunity to study how the source size and asymmetry in particle emission depend on the initial conditions of the collision. It also allows one to examine these parameters in the vicinity of the theoretical critical point. In these proceedings, we present STAR results of pion-kaon femtoscopy at mid-rapidity in Au+Au collisions at \\sqrt{sNN} = 7.7, 19.6 and 39 GeV.

  10. Pion-kaon femtoscopy in Au+Au collisions at STAR

    NASA Astrophysics Data System (ADS)

    Poniatowska, Katarzyna

    2015-05-01

    Femtoscopy analysis allows us to extract information about the properties of particle emission source created after collision. From HBT of two correlated pions one can calculate source sizes; in addition, from the non-identical particle correlations, e.g. pion-kaon femtoscopy, one can obtain information not only about source sizes but the asymmetry in the emission processes of particles of different types as well. Such asymmetry gives knowledge of which kind of particles are emitted first/second and/or from which region of the source. The studies of non-identical particle femtoscopy for different collision energies gives us the opportunity to study how the source size and asymmetry in particle emission depend on the initial conditions of the collision. In these proceedings, we will present STAR results of pion-kaon femtoscopy at mid-rapidity in Au + Au collisions from the Beam Energy Scan program.

  11. Neutral pion production in Au+Au collisions at sNN=200 GeV

    NASA Astrophysics Data System (ADS)

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Baumgart, S.; Beavis, D. R.; Bellwied, R.; Benedosso, F.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Biritz, B.; Bland, L. C.; Bnzarov, I.; Bombara, M.; Bonner, B. E.; Bouchet, J.; Braidot, E.; Brandin, A. V.; Bruna, E.; Bueltmann, S.; Burton, T. P.; Bystersky, M.; Cai, X. Z.; Caines, H.; Sánchez, M. Calderón De La Barca; Catu, O.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K. E.; Christie, W.; Clarke, R. F.; Codrington, M. J. M.; Corliss, R.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; Silva, L. C. De; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; de Souza, R. Derradi; Didenko, L.; Djawotho, P.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Dunlop, J. C.; Mazumdar, M. R. Dutta; Efimov, L. G.; Elhalhuli, E.; Elnimr, M.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gaillard, L.; Gangadharan, D. R.; Ganti, M. S.; Garcia-Solis, E. J.; Geromitsos, A.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S. M.; Guimaraes, K. S. F. F.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; He, W.; Heinz, M.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D. J.; Hollis, R. S.; Huang, H. Z.; Humanic, T. J.; Huo, L.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jena, C.; Jin, F.; Jones, C. L.; Jones, P. G.; Joseph, J.; Judd, E. G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitan, J.; Kauder, K.; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V. Yu.; Kikola, D. P.; Kiryluk, J.; Kisiel, A.; Klein, S. R.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Konzer, J.; Kopytine, M.; Koralt, I.; Korsch, W.; Kotchenda, L.; Kouchpil, V.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Krus, M.; Kuhn, C.; Kumar, L.; Kurnadi, P.; Lamont, M. A. C.; Landgraf, J. M.; Lapointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Lee, J. H.; Leight, W.; Levine, M. J.; Li, C.; Li, N.; Li, Y.; Lin, G.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ludlam, T.; Ma, G. L.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mall, O. I.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; Matulenko, Yu. A.; McDonald, D.; McShane, T. S.; Meschanin, A.; Milner, R.; Minaev, N. G.; Mioduszewski, S.; Mischke, A.; Mohanty, B.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Netrakanti, P. K.; Ng, M. J.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okada, H.; Okorokov, V.; Olson, D.; Pachr, M.; Page, B. S.; Pal, S. K.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Pile, P.; Planinic, M.; Ploskon, M. A.; Pluta, J.; Plyku, D.; Poljak, N.; Poskanzer, A. M.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Pujahari, P. R.; Putschke, J.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Redwine, R.; Reed, R.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Sahoo, R.; Sakai, S.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sarsour, M.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S. S.; Shi, X.-H.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Skoby, M. J.; Smirnov, N.; Sorensen, P.; Sowinski, J.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Staszak, D.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Symons, T. J. M.; de Toledo, A. Szanto; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Timoshenko, S.; Tlusty, D.; Tokarev, M.; Trainor, T. A.; Tram, V. N.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; Buren, G. Van; Nieuwenhuizen, G. Van; Vanfossen, J. A., Jr.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Videbaek, F.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Whitten, C., Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xie, W.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yang, Y.; Yepes, P.; Yip, K.; Yoo, I.-K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, S.; Zhang, W. M.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, Y.; Zhong, C.; Zhou, J.; Zhu, X.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zuo, J. X.

    2009-10-01

    The results of midrapidity (0Au collisions, measured by the STAR experiment, are presented. The neutral pions are reconstructed from photons measured either by the STAR Barrel Electro-Magnetic Calorimeter or by the Time Projection Chamber via tracking of conversion electron-positron pairs. Our measurements are compared to previously published π± and π0 results. The nuclear modification factors RCP and RAA of π0 are also presented as a function of pT. In the most central Au+Au collisions, the binary collision scaled π0 yield at high pT is suppressed by a factor of about 5 compared to the expectation from the yield of p+p collisions. Such a large suppression is in agreement with previous observations for light quark mesons and is consistent with the scenario that partons suffer considerable energy loss in the dense medium formed in central nucleus-nucleus collisions at the Relativistic Heavy Ion Collider.

  12. U+U and Cu+Au results from PHENIX

    NASA Astrophysics Data System (ADS)

    Iordanova, Aneta; PHENIX Collaboration

    2013-08-01

    The flexibility of RHIC to collide different nuclei provides experiments with a rich set of data to systematically test models and scaling behaviors in various collision systems. The latest RHIC run collided U+U and Cu+Au nuclei. These collisions promise an array of unique initial geometrical configurations. For example, in U+U collisions the slightly elongated nuclei overlap in a variety of different ways such that, even at zero impact parameter, distinct configurations exist. In central Cu+Au collisions the Cu nucleus is completely embedded within the Au. Such geometries present an opportunity to measure the wide range of initial energy densities of these systems. They also allow the study of some unique features arising from these configurations. In particular, the odd harmonics from the Cu+Au system offer sensitivity to v3 generated from the collision geometry as opposed to fluctuations in a symmetric system. In these proceedings the analysis status of the recently taken U+U and Cu+Au data in PHENIX is presented. The results from the global particle production and the challenges in analyzing these asymmetric systems is discussed.

  13. The diagnostic and clinical significance of café-au-lait macules.

    PubMed

    Shah, Kara N

    2010-10-01

    Café-au-lait, also referred to as café-au-lait spots or café-au-lait macules, present as well-circumscribed, evenly pigmented macules and patches that range in size from 1 to 2 mm to greater than 20 cm in greatest diameter. Café-au-lait are common in children. Although most café-au-lait present as 1 or 2 spots in an otherwise healthy child, the presence of multiple café-au-lait, large segmental café-au-lait, associated facial dysmorphism, other cutaneous anomalies, or unusual findings on physical examination should suggest the possibility of an associated syndrome. While neurofibromatosis type 1 is the most common syndrome seen in children with multiple café-au-lait, other syndromes associated with one or more café-au-lait include McCune-Albright syndrome, Legius syndrome, Noonan syndrome and other neuro-cardio-facialcutaneous syndromes, ring chromosome syndromes, and constitutional mismatch repair deficiency syndrome. PMID:20888463

  14. Proton and pion production relative to the reaction plane in Au + Au collisions at 11A GeV/c

    SciTech Connect

    David, G.; Herrmann, N. |; Drigert, M.; Dai, Y.; Filimonov, K.; Clemen, M.; Chang, W.C.; Dee, J.; Hemmick, T.K.; Johnson, S.C. Dietzsch, O.; Cormier, T.M.; Hall, J.R.

    1997-12-01

    Results are presented of an analysis of proton and charged pion azimuthal distributions measured with respect to the reaction plane in Au + Au collisions at a beam momentum of about 11A GeV/c. The azimuthal anisotropy is studied as a function of particle rapidity and transverse momentum for different centralities of the collisions. The triple differential (in rapidity, transverse momentum, and azimuthal angle) distributions are reconstructed. A comparison of the results with a previous analysis of charged-particle and transverse energy flow as well as with model predictions are presented. {copyright} {ital 1997} {ital The American Physical Society}

  15. Mechanical Properties and Fracture Behavior of Nanoporous Au

    SciTech Connect

    Biener, J; Hodge, A M; Wang, Y M; Hayes, J R; Hamza, A V

    2005-06-16

    Nanoporous metals have recently attracted considerable interest fueled by potential sensor and actuator applications. From a material science point of view, one of the key issues in this context is the synthesis of nanoporous metals with both high tensile and compressive strength. Nanoporous gold (np-Au) has been suggested as a candidate material for this application due to its monolithic character. The material can be synthesized by electrochemically-driven dealloying of Ag-Au alloys, and exhibits an open sponge-like structure of interconnecting ligaments with a typical pore size distribution on the nanometer length scale. However, besides the observation of a ductile-brittle transition very little is known about the mechanical behavior of this material. Here, we present our results regarding the mechanical properties and the fracture behavior of np-Au. Depth-sensing nanoindentation reveals that the yield strength of np-Au is almost one order of magnitude higher than the value predicted by scaling laws developed for macroscopic open-cell foams. The unexpectedly high value of the yield strength indicates the presence of a distinct size effect of the mechanical properties due to the sub-micron dimensions of the ligaments, thus potentially opening a door to a new class of high yield strength--low density materials. The failure mechanism of np-Au under tensile stress was evaluated by microscopic examination of fracture surfaces using scanning electron microscopy. On a macroscopic level, np-Au is a very brittle material. However, microscopically np-Au is very ductile as ligaments strained by as much as 200% can be observed in the vicinity of crack tips. Cell-size effects on the microscopic failure mechanism were studied by annealing experiments whereby increasing the typical pore size/ligament diameter from {approx}100 nm to {approx}1{micro}m.

  16. Global polarization measurement in Au+Au collisions

    SciTech Connect

    Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett,J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Bai,Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Benedosso, F.; Bhardwaj, S.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L.C.; Blyth, S.-L.; Bonner, B.E.; Botje, M.; Bouchet, J.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai,X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Catu,O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen,H.F.; Chen, J.H.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cosentino, M.R.; Cramer, J.G.; Crawford,H.J.; Das, D.; Das, S.; Daugherity, M.; de Moura, M.M.; Dedovich, T.G.; DePhillips, M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Djawotho,P.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch,E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C.A.; Gaillard, L.; Ganti,M.S.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.S.; Gorbunov, Y.G.; Gos,H.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guimaraes, K.S.F.F.; Guo,Y.; Gupta, N.; Gutierrez, T.D.; Haag, B.; Hallman, T.J.; Hamed, A.; Harris, J.W.; He, W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte,B.; Hirsch, A.; Hjort, E.; Hoffman, A.M.; Hoffmann, G.W.; Horner, M.J.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Jacobs,P.; Jacobs, W.W.; Jakl, P.; Jia, F.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Khodyrev,V.Yu.; Kim, B.C.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klein,S.R.; Kocoloski, A.; Koetke, D.D.; et al.

    2007-08-02

    The system created in non-central relativisticnucleus-nucleus collisions possesses large orbital angular momentum. Dueto spin-orbit coupling, particles produced in such a system could becomeglobally polarized along the direction of the system angular momentum. Wepresent the results of Lambda and anti-Lambda hyperon global polarizationmeasurements in Au+Au collisions at sqrt sNN=62.4 GeV and 200 GeVperformed with the STAR detector at RHIC. The observed globalpolarization of Lambda and anti-Lambda hyperons in the STAR acceptance isconsistent with zero within the precision of the measurements. Theobtained upper limit, lbar P Lambda, anti-Lambda rbar<= 0.02, iscompared to the theoretical values discussed recently in theliterature.

  17. Nuclear Modification of Jet Fragmentation in Au+Au Collisions

    NASA Astrophysics Data System (ADS)

    Rowan, Zachary; Phenix Collaboration

    2015-10-01

    The characterization of energy in the quark gluon plasma is facilitated by measurements of modifications to the observed jet fragmentation. A favorable channel of study relies on direct photons created in the initial parton interactions of heavy ion collisions. Such a photon traverses the created medium unscathed and grants us a proxy for the transverse momentum of an away side jet. PHENIX Au+Au data recorded at √{sNN} = 200 GeV during RHIC run 14 benefit from the background rejection capability of the silicon vertex detector, enabling the extraction of a higher purity hadron signal. This advantage, combined with a larger integrated luminosity, allows previous PHENIX measurements of fragmentation functions to be extended to greater jet energies. In this talk, the status of the analysis of direct photon hadron correlations with the new data set will be discussed.

  18. Temperature-independent formation of Au nanoparticles in ionic liquids by arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Hatakeyama, Yoshikiyo; Kimura, Satoshi; Kameyama, Tatsuya; Agawa, Yoshiaki; Tanaka, Hiroyuki; Judai, Ken; Torimoto, Tsukasa; Nishikawa, Keiko

    2016-08-01

    An effective preparation method of Au nanoparticles (NPs) is presented, wherein an arc plasma deposition technique is combined with ionic liquids (ILs) used as capture media. This method requires no chemical reaction. By selecting ILs, size-controlled Au NPs are produced easily and on a massive scale.

  19. Presentation Timer

    Energy Science and Technology Software Center (ESTSC)

    2010-06-23

    Abstract Conferences and Meetings feature many presentations on a tight schedule. The Session Timer system provides an electronic display for showing the remaining time in a presentation. It provides continuous feedback so the speaker can judge the pace throughout a presentation. The timer automates the job so the session chairman does not have to awkwardly interrupt the speaker.

  20. Stream dynamics between 1 AU and 2 AU: A detailed comparison of observations and theory

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Pizzo, V.; Lazarus, A.; Gazis, P. R.

    1984-01-01

    A radial alignment of three solar wind stream structures observed by IMP-7 and -8 (at 1.0 AU) and Voyager 1 and 2 (in the range 1.4 to 1.8 AU) in late 1977 is presented. It is demonstrated that several important aspects of the observed dynamical evolution can be both qualitatively and quantitatively described with a single-fluid 2-D MHD numerical model of quasi-steady corotating flow, including accurate prediction of: (1) the formation of a corotating shock pair at 1.75 AU in the case of a simple, quasi-steady stream; (2) the coalescence of the thermodynamic and magnetic structures associated with the compression regions of two neighboring, interacting, corotating streams; and (3) the dynamical destruction of a small (i.e., low velocity-amplitude, short spatial-scale) stream by its overtaking of a slower moving, high-density region associated with a preceding transient flow. The evolution of these flow systems is discussed in terms of the concepts of filtering and entrainment.

  1. Self-decorated Au nanoparticles on antireflective Si pyramids with improved hydrophobicity

    NASA Astrophysics Data System (ADS)

    Saini, C. P.; Barman, A.; Kumar, M.; Satpati, B.; Som, T.; Kanjilal, A.

    2016-04-01

    Post-deposition annealing mediated evolution of self-decorated Au nanoparticles (NPs) on chemically etched Si pyramids is presented. A distinct transformation of Si surfaces from hydrophilic to hydrophobic is initially found after chemical texturing, showing an increase in contact angle (CA) from 58° to 98° (±1°). Further improvement of hydrophobicity with CA up to ˜118° has been established after annealing a 10 nm thick Au-coated Si pyramids at 400 °C that led to the formation of Au NPs on Si facets along with self-ordering at the pyramid edges. Detailed x-ray diffraction studies suggest the evolution of crystalline Au NPs on strained Si facets. Microstructural studies, however, indicate no mixing of Au and Si atoms at the Au/Si interfaces, instead of forming Au nanocrystals at 400 °C. The improved hydrophobicity of Si pyramids, even with Au NPs can be explained in the light of a decrease in solid fractional surface area according to Wenzel's model. Moreover, a sharp drop in specular reflectance from Si pyramids in the range of 300-800 nm, especially in the ultraviolet region up to ˜0.4% is recorded in the presence of Au NPs by ultraviolet-visible spectroscopy, reflecting the possible use in photovoltaic devices with improved antireflection property.

  2. Synthesis of Au-SiO2 Composite Nanospheres and Their Catalytic Activity.

    PubMed

    Dexuan, Wang; Guian, Li; Qingyan, Han; Ziqiang, Wang; Liping, Pan; Zhonayue, Zhang; Hairong, Zhenq

    2016-04-01

    We report a simple and environmentally friendly approach to the synthesis of Au-SiC2 composite nanospheres. Our method presents a route for the decoration of preformed amine functionalized SiO2 nanospheres by in situ formation of Au nanoparticles at three different concentrations of Au precursor (HAuCl4). Herein, the silane coupling agent (KH-550) is used as an intermediary to connect the Au nanoparticles to the surfaces of the SiO2 nanospheres, which helps avoid the aggregation of Au nanoparticles. The crystal structure, chemical elements, morphology and catalytic properties of the Au-SiO2 composite nanospheres were analyzed by transmission electron microscopy (TEM), X-Ray powder diffraction (XRD), UV-vis-spectrophotometer (UV-vis) and X-ray photoelectron spectroscopy (XPS). The analytical results demonstrate that the Au nanoparticles (4-9 nm) were homogeneously distributed on the surface of the SiO2 nanospheres, which had a good FCC crystal structure. Moreover, the Au-SiO2 composite nanospheres exhibited good catalytic properties, measured by their ability to reduce organic dyes. The Au-SiO2 composite nanospheres are promising candidates for applications in catalysis and wastewater treatment. PMID:27451717

  3. CO Oxidation on Au/TiO2: Condition-Dependent Active Sites and Mechanistic Pathways.

    PubMed

    Wang, Yang-Gang; Cantu, David C; Lee, Mal-Soon; Li, Jun; Glezakou, Vassiliki-Alexandra; Rousseau, Roger

    2016-08-24

    We present results of ab initio electronic structure and molecular dynamics simulations (AIMD), as well as a microkinetic model of CO oxidation catalyzed by TiO2 supported Au nanocatalysts. A coverage-dependent microkinetic analysis, based on energetics obtained with density functional methods, shows that the dominant kinetic pathway, activated oxygen species, and catalytic active sites are all strongly depended on both temperature and oxygen partial pressure. Under oxidizing conditions and T < 400 K, the prevalent pathway involves a dynamic single atom catalytic mechanism. This reaction is catalyzed by a transient Au-CO species that migrates from the Au-cluster onto a surface oxygen adatom. It subsequently reacts with the TiO2 support via a Mars van Krevelen mechanism to form CO2 and finally the Au atom reintegrates back into the gold cluster to complete the catalytic cycle. At 300 ≤ T ≤ 600 K, oxygen-bound single Oad-Au(+)-CO sites and the perimeter Au-sites of the nanoparticle work in tandem to optimally catalyze the reaction. Above 600 K, a variety of alternate pathways associated with both single-atom and the perimeter sites of the Au nanoparticle are found to be active. Under low oxygen pressures, Oad-Au(+)-CO species can be a source of catalyst deactivation and the dominant pathway involves only Au-perimeter sites. A detailed comparison of the current model and the existing literature resolves many apparent inconsistencies in the mechanistic interpretations. PMID:27480512

  4. The Orbital Distribution of Trans-Neptunian Objects Beyond 50 au

    NASA Astrophysics Data System (ADS)

    Nesvorný, David; Vokrouhlický, David; Roig, Fernando

    2016-08-01

    The dynamical structure of the Kuiper Belt beyond 50 au is not well understood. Here we report results of a numerical model with long-range, slow, and grainy migration of Neptune. The model implies that bodies scattered outward by Neptune to semimajor axes a\\gt 50 {au} often evolve into resonances which subsequently act to raise the perihelion distances of orbits to q\\gt 40 {au}. The implication of the model is that the orbits with 50\\lt a\\lt 100 {au} and q\\gt 40 {au} should cluster near (but not in) the resonances with Neptune (3:1 at a = 62.6 au, 4:1 at a=75.9 {au}, 5:1 at a=88.0 {au}, etc.). The recent detection of several distant Kuiper Belt Objects (KBOs) near resonances is consistent with this prediction, but it is not yet clear whether the orbits are really non-resonant as our model predicts. We estimate from the model that there should presently be ∼1600–2400 bodies at the 3:1 resonance and ∼1000–1400 bodies at the 4:1 resonance (for q\\gt 40 {au} and diameters D\\gt 100 km). These results favorably compare with the population census of distant KBOs inferred from existing observations.

  5. Hybrid colloidal Au-CdSe pentapod heterostructures synthesis and their photocatalytic properties.

    PubMed

    Haldar, Krishna Kanta; Sinha, Godhuli; Lahtinen, Jouko; Patra, Amitava

    2012-11-01

    In this report, we present a self-driven chemical process to design exclusive Au/CdSe pentapod heterostructures with Au core and CdSe arms. We have analyzed these heterostructures using high-resolution transmission electron microscope (HRTEM), high angle annular dark field-scanning transmission electron microscopic (HAADF-STEM), X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) studies. Microscopic studies suggest that pentapod arms of CdSe are nucleated on the (111) facets of Au and linearly grown only along the [001] direction. From the XPS study, the shifting of peak positions in the higher binding energy region for Au/CdSe heterostructures compared to Au nanoparticles has been found which indicates the charge transfer from CdSe to Au in heterostructures. The steady state and time resolved spectroscopic studies unambiguously confirm the electron transfer from photoexcited CdSe to Au, and the rate of electron transfer is found to be 3.58×10⁸ s⁻¹. It is interesting to note that 87.2% of R6G dye is degraded by the Au/CdSe heterostructures after 150 min UV irradiation, and the apparent rate constant for Au/CdSe heterostructures is found to be 0.013 min⁻¹. This new class of metal-semiconductor heterostructures opens up new possibilities in photocatalytic, solar energy conversion, photovoltaic, and other new emerging applications. PMID:23113704

  6. Aggregation of [Au(CN)4]- anions: examination by crystallography and 15N CP-MAS NMR and the structural factors influencing intermolecular Au···N interactions.

    PubMed

    Geisheimer, Andrew R; Wren, John E C; Michaelis, Vladimir K; Kobayashi, Masayuki; Sakai, Ken; Kroeker, Scott; Leznoff, Daniel B

    2011-02-21

    To investigate the factors influencing the formation of intermolecular Au···NC interactions between [Au(CN)(4)](-) units, a series of [cation](n+)[Au(CN)(4)](n) double salts was synthesized, structurally characterized and probed by IR and (15)N{(1)H} CP-MAS NMR spectroscopy. Thus, [(n)Bu(4)N][Au(CN)(4)], [AsPh(4)][Au(CN)(4)], [N(PPh(3))(2)][Au(CN)(4)], [Co(1,10-phenanthroline)(3)][Au(CN)(4)](2), and [Mn(2,2';6',2''-terpyridine)(2)][Au(CN)(4)](2) show [Au(CN)(4)](-) anions that are well-separated from one another; no Au-Au or Au···NC interactions are present. trans-[Co(1,2-diaminoethane)(2)Cl(2)][Au(CN)(4)] forms a supramolecular structure, where trans-[Co(en)(2)Cl(2)](+) and [Au(CN)(4)](-) ions are found in separate layers connected by Au-CN···H-N hydrogen-bonding; weak Au···NC coordinate bonds complete octahedral Au(III) centers, and support a 2-D (4,4) network motif of [Au(CN)(4)](-)-units. A similar structure-type is formed by [Co(NH(3))(6)][Au(CN)(4)](3)·(H(2)O)(4). In [Ni(1,2-diaminoethane)(3)][Au(CN)(4)](2), intermolecular Au···NC interactions facilitate formation of 1-D chains of [Au(CN)(4)](-) anions in the supramolecular structure, which are separated from one another by [Ni(en)(3)](2+) cations. In [1,4-diazabicyclo[2.2.2]octane-H][Au(CN)(4)], the monoprotonated amine cation forms a hydrogen-bond to the [Au(CN)(4)](-) unit on one side, while coordinating to the axial sites of the gold(III) center through the unprotonated amine on the other, thereby generating a 2-D (4,4) net of cations and anions; an additional, uncoordinated [Au(CN)(4)](-)-unit lies in the central space of each grid. This body of structural data indicates that cations with hydrogen-bonding groups can induce intermolecular Au···NC interactions, while the cationic charge, shape, size, and aromaticity have little effect. While the ν(CN) values are poor indicators of the presence or absence of N-cyano bridging between [Au(CN)(4)](-)-units (partly because of the very low

  7. Cometary Activity Beyond 4 AU

    NASA Astrophysics Data System (ADS)

    Womack, M.

    2000-10-01

    Recent observations of the distantly active comets 29 P/Schwassmann-Wachmann 1, 2060 Chiron, and C/1995 O1 (Hale-Bopp) are consistent with models that predict that the activity beyond 4 AU is dominated by outgassing of CO and CO2 molecules trapped in an amorphous water ice surface undergoing crystallization. The nominal CO production rates in Hale-Bopp, SW 1 and Chiron over the range of r = 4 to 9 AU are consistent with Q(CO) = (2.9+/-0.5)x1030r{(-2.5 +/- 0.1)}, with sporadic outbursts superimposed. The data indicate that the gas production rates in distant comets are primarily determined by the composition, and not the size, of the nucleus. The dust production rates, however, are very different among these comets and are not well-correlated with heliocentric distance. Thus, the gas and dust mixtures may not be uniform amongst these comets, nor in an individual comet. Development and sublimation of an icy grain coma at ~ 5 AU appears to be a common feature in distantly active comets. Sublimation of such icy grains is probably the main source of emission of OH, CH3OH, HCN, and H2S in comets beyond 4 AU. Studying the energetics of these phenomena provides an excellent opportunity to learn more about the composition and physical behavior of comet nuclei, as well as other icy bodies in the outer solar system, such as moons and Kuiper Belt Objects. This work was funded by the NSF CAREER Program.

  8. Atomic Structure of Au 329 (SR) 84 Faradaurate Plasmonic Nanomolecules

    SciTech Connect

    Kumara, Chanaka; Zuo, Xiaobing; Ilavsky, Jan; Cullen, David A.; Dass, Amala

    2015-05-21

    To design novel nanomaterials, it is important to precisely control the composition, determine the atomic structure, and manipulate the structure to tune the materials property. Here we present a comprehensive characterization of the material whose composition is Au329(SR)84 precisely, therefore referred to as a nanomolecule. The size homogeneity was shown by electron microscopy, solution X-ray scattering, and mass spectrometry. We proposed its atomic structure to contain the Au260 core using experiments and modeling of a total-scattering-based atomic-pair distribution functional analysis. HAADF- STEM images shows fcc-like 2.0 ± 0.1 nm diameter nanomolecules.

  9. Atomic Structure of Au329(SR)84 Faradaurate Plasmonic Nanomolecules

    DOE PAGESBeta

    Kumara, Chanaka; Zuo, Xiaobing; Ilavsky, Jan; Cullen, David; Dass, Amala

    2015-04-03

    To design novel nanomaterials, it is important to precisely control the composition, determine the atomic structure, and manipulate the structure to tune the materials property. Here we present a comprehensive characterization of the material whose composition is Au329(SR)84 precisely, therefore referred to as a nanomolecule. The size homogeneity was shown by electron microscopy, solution X-ray scattering, and mass spectrometry. We proposed its atomic structure to contain the Au260 core using experiments and modeling of a total-scattering-based atomic-pair distribution functional analysis. HAADF-STEM images shows fcc-like 2.0 ± 0.1 nm diameter nanomolecules.

  10. Graphene nanoribbons synthesized from molecular precursor polymerization on Au(110)

    SciTech Connect

    Massimi, Lorenzo; Ourdjini, Oualid; Della Pia, Ada; Mariani, Carlo; Betti, Maria Grazia; Cavaliere, Emanuele; Gavioli, Luca

    2015-06-23

    A spectroscopic study of 10,10-dibromo-9,9 bianthracene (DBBA) molecules deposited on the Au(110) surface is presented, by means of ultraviolet and X-ray photoemission, and X-ray absorption spectroscopy. Through a thermally activated procedure, these molecular precursors polymerize and eventually form graphene nanoribbons (GNRs) with atomically controlled shape and width, very important building blocks for several technological applications. The GNRs observed by scanning tunneling microscopy (STM) appear as short segments on top of the gold surface reconstruction, pointing out the delicate balance among surface diffusion and surface corrugation in their synthesis on the Au(110) surface.

  11. Controlled electrodeposition of Au monolayer film on ionic liquid

    NASA Astrophysics Data System (ADS)

    Ma, Qiang; Pang, Liuqing; Li, Man; Zhang, Yunxia; Ren, Xianpei; Liu, Shengzhong Frank

    2016-05-01

    Gold (Au) nanoparticles have been attractive for centuries for their vibrant appearance enhanced by their interaction with sunlight. Nowadays, there have been tremendous research efforts to develop them for high-tech applications including therapeutic agents, sensors, organic photovoltaics, medical applications, electronics and catalysis. However, there remains to be a challenge to fabricate a monolayer Au coating with complete coverage in controlled fashion. Here we present a facile method to deposit a uniform Au monolayer (ML) film on the [BMIM][PF6] ionic liquid substrate using an electrochemical deposition process. It demonstrates that it is feasible to prepare a solid phase coating on the liquid-based substrate. Moreover, the thickness of the monolayer coating can be controlled to a layer-by-layer accuracy.

  12. Direct electrochemical oxidation of S-captopril using gold electrodes modified with graphene-AuAg nanocomposites

    PubMed Central

    Pogacean, Florina; Biris, Alexandru R; Coros, Maria; Lazar, Mihaela Diana; Watanabe, Fumiya; Kannarpady, Ganesh K; Al Said, Said A Farha; Biris, Alexandru S; Pruneanu, Stela

    2014-01-01

    In this paper, we present a novel approach for the electrochemical detection of S-captopril based on graphene AuAg nanostructures used to modify an Au electrode. Multi-layer graphene (Gr) sheets decorated with embedded bimetallic AuAg nanoparticles were successfully synthesized catalytically with methane as the carbon source. The two catalytic systems contained 1.0 wt% Ag and 1.0 wt% Au, while the second had a larger concentration of metals (1.5 wt% Ag and 1.5 wt% Au) and was used for the synthesis of the Gr-AuAg-1 and Gr-AuAg-1.5 multicomponent samples. High-resolution transmission electron microscopy analysis indicated the presence of graphene flakes that had regular shapes (square or rectangular) and dimensions in the tens to hundreds of nanometers. We found that the size of the embedded AuAg nanoparticles varied between 5 and 100 nm, with the majority being smaller than 20 nm. Advanced scanning transmission electron microscopy studies indicated a bimetallic characteristic of the metallic clusters. The resulting Gr-AuAg-1 and Gr-AuAg-1.5 samples were used to modify the surface of commonly used Au substrates and subsequently employed for the direct electrochemical oxidation of S-captopril. By comparing the differential pulse voltammograms recorded with the two modified electrodes at various concentrations of captopril, the peak current was determined to be well-defined, even at relatively low concentration (10−5 M), for the Au/Gr-AuAg-1.5 electrode. In contrast, the signals recorded with the Au/Gr-AuAg-1 electrode were poorly defined within a 5×10−6 to 5×10−3 M concentration range, and many of them overlapped with the background. Such composite materials could find significant applications in nanotechnology, sensing, or nanomedicine. PMID:24596464

  13. Strange and multistrange particle production in Au + Au collisions at {radical}(s{sub NN})=62.4 GeV

    SciTech Connect

    Aggarwal, M. M.; Bhati, A. K.; Pruthi, N. K.; Ahammed, Z.; Dong, X.; Grebenyuk, O.; Hjort, E.; Jacobs, P.; Kikola, D. P.; Kiryluk, J.; Klein, S. R.; Masui, H.; Matis, H. S.; Naglis, M.; Odyniec, G.; Olson, D.; Ploskon, M. A.; Poskanzer, A. M.; Powell, C. B.; Ritter, H. G.

    2011-02-15

    We present results on strange and multistrange particle production in Au + Au collisions at {radical}(s{sub NN})=62.4 GeV as measured with the STAR detector at RHIC. Midrapidity transverse momentum spectra and integrated yields of K{sub S}{sup 0}, {Lambda}, {Xi}, and {Omega} and their antiparticles are presented for different centrality classes. The particle yields and ratios follow a smooth energy dependence. Chemical freeze-out parameters, temperature, baryon chemical potential, and strangeness saturation factor obtained from the particle yields are presented. Intermediate transverse momentum (p{sub T}) phenomena are discussed based on the ratio of the measured baryon-to-meson spectra and nuclear modification factor. The centrality dependence of various measurements presented show a similar behavior as seen in Au + Au collisions at {radical}(s{sub NN})=200 GeV.

  14. Strange and Multi-strange Particle Production in Au+Au Collisions at sqrt sNN = 62.4GeV

    SciTech Connect

    Aggarwal, M.M.; Dunlop, J.; et al.

    2011-02-04

    We present results on strange and multistrange particle production in Au + Au collisions at {radical}s{sub NN} = 62.4 GeV as measured with the STAR detector at RHIC. Midrapidity transverse momentum spectra and integrated yields of K{sub S}{sup 0}, {lambda}, {Xi}, and {Omega} and their antiparticles are presented for different centrality classes. The particle yields and ratios follow a smooth energy dependence. Chemical freeze-out parameters, temperature, baryon chemical potential, and strangeness saturation factor obtained from the particle yields are presented. Intermediate transverse momentum (p{sub T}) phenomena are discussed based on the ratio of the measured baryon-to-meson spectra and nuclear modification factor. The centrality dependence of various measurements presented show a similar behavior as seen in Au + Au collisions at {radical}s{sub NN} = 200 GeV.

  15. Biological synthesis of Au nanoparticles using liquefied mash of cassava starch and their functionalization for enhanced hydrolysis of xylan by recombinant xylanase.

    PubMed

    Zeng, Sumei; Du, Liangwei; Huang, Meiying; Feng, Jia-Xun

    2016-05-01

    Au nanoparticles (AuNPs) have shown the potential for a variety of applications due to their unique physical and chemical properties. In this study, a facile and affordable method for the synthesis of AuNPs via the liquefied mash of cassava starch has been described and the functionalized AuNPs by L-cysteine improved activity of recombinant xylanase was demonstrated. UV-Vis absorption spectroscopy, transmission electron microscopy, and zeta potential measurements were performed to characterize the AuNPs and monitor their synthesis. The presence of Au was confirmed by energy-dispersive X-ray spectroscopy (EDX) and the X-ray diffraction patterns showed that Au nanocrystals were face-centered cubic. The C=O stretching vibration in the Fourier transform infrared spectrum of AuNPs suggested that the hemiacetal C-OH of sugar molecules performed the reduction of Au³⁺ to Au⁰. The presence of C and O in the EDX spectrum and the negative zeta potential of AuNPs suggested that the biomolecules present in liquefied cassava mash were responsible for the stabilization of AuNPs. The surface of AuNPs was easily functionalized by L-cysteine, which improved the stability of AuNPs. Moreover, cysteine-functionalized AuNPs could significantly improve recombinant xylanase efficiency and stability. PMID:26864877

  16. Superconductivity in uranium compounds with Cu3Au structure

    NASA Astrophysics Data System (ADS)

    Ott, H. R.; Hulliger, F.; Rudigier, H.; Fisk, Z.

    1985-02-01

    Superconductivity has been observed in uranium compounds with partly disordered Cu3Au-type crystal structure and interatomic U-U distances of more than 4 Å. Low-temperature specific-heat experiments reveal no anomalous enhancement of the electronic specific heat thus distinguishing the present materials from the unconventional superconductors UBe13 and UPt3.

  17. Atomic and electronic structures of Si(1 1 1)-\\left(\\sqrt{\\mathbf{3}}\\times\\sqrt{\\mathbf{3}}\\right)\\text{R}\\mathbf{3}{{\\mathbf{0}}^{\\circ}} -Au and (6 × 6)-Au surfaces

    NASA Astrophysics Data System (ADS)

    Patterson, C. H.

    2015-12-01

    Si(1 1 1)-Au surfaces with around one monolayer of Au exhibit many ordered structures and structures containing disordered domain walls. Hybrid density functional theory (DFT) calculations presented here reveal the origin of these complex structures and tendency to form domain walls. The conjugate honeycomb chain trimer (CHCT) structure of the \\sqrt{3} -Au phase contains Si atoms with non-bonding surface states which can bind Au atoms in pairs in interstices of the CHCT structure and make this surface metallic. Si adatoms adsorbed on the \\sqrt{3} -Au surface induce a gapped surface through interaction with the non-bonding states. Adsorption of extra Au atoms in interstitial sites of the \\sqrt{3} -Au surface is stabilized by interaction with the non-bonding orbitals and leads to higher coverage ordered structures including the ≤ft(6× 6\\right) -Au phase. Extra Au atoms bound in interstitial sites of the \\sqrt{3} -Au surface result in top layer Si atoms with an SiAu4 butterfly wing configuration. The structure of a ≤ft(6× 6\\right) -Au phase, whose in-plane top atomic layer positions were previously determined by an electron holography technique (Grozea et al 1998 Surf. Sci. 418 32), is calculated using total energy minimization. The Patterson function for this structure is calculated and is in good agreement with data from an in-plane x-ray diffraction study (Dornisch et al 1991 Phys. Rev. B 44 11221). Filled and empty state scanning tunneling microscopy (STM) images are calculated for domain walls and the ≤ft(6× 6\\right) -Au structure. The ≤ft(6× 6\\right) -Au phase is 2D chiral and this is evident in computed and actual STM images. ≤ft(6× 6\\right) -Au and domain wall structures contain the SiAu4 motif with a butterfly wing shape. Chemical bonding within the Si-Au top layers of the \\sqrt{3} -Au and ≤ft(6× 6\\right) -Au surfaces is analyzed and an explanation for the SiAu4 motif structure is given.

  18. ΛΛ correlation function in Au + Au collisions at √sNN = 200 GeV

    SciTech Connect

    Adamczyk, L.

    2015-01-12

    In this study, we present ΛΛ correlation measurements in heavy-ion collisions for Au+Au collisions at √sNN = 200 GeV using the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). The Lednický-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the ΛΛ correlation function and interaction parameters for di-hyperon searches are discussed.

  19. V0 Reconstruction of Strange Hadrons in Au+Au Collisions at 1.23 AGeV with HADES

    NASA Astrophysics Data System (ADS)

    Scheib, T.; HADES Collaboration

    2015-04-01

    Preliminary results on the production of weakly decaying strange hadrons are reported for collisions of Au+Au at 1.23 AGeV beam energy studied with the HADES detector at GSI in Darmstadt. At this collision energy all strange particles are created below their elementary threshold. The reconstruction of the investigated particles (i.e. Λ and K0s) via the topology of their charged decay products (V0 reconstruction) is presented in detail. From the corrected yields of Λ and K0s the ratio K0S/Λ can be calculated and included into a statistical model fit.

  20. ΛΛ correlation function in Au + Au collisions at √sNN = 200 GeV

    DOE PAGESBeta

    Adamczyk, L.

    2015-01-12

    In this study, we present ΛΛ correlation measurements in heavy-ion collisions for Au+Au collisions at √sNN = 200 GeV using the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). The Lednický-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the ΛΛ correlation function and interaction parameters for di-hyperon searches are discussed.

  1. Directed flow in Au+Au collisions at sNN=62.4 GeV

    NASA Astrophysics Data System (ADS)

    Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Badyal, S. K.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Bekele, S.; Belaga, V. V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Berger, J.; Bezverkhny, B. I.; Bharadwaj, S.; Bhasin, A.; Bhati, A. K.; Bhatia, V. S.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Billmeier, A.; Bland, L. C.; Blyth, C. O.; Blyth, S.-L.; Bonner, B. E.; Botje, M.; Boucham, A.; Bouchet, J.; Brandin, A. V.; Bravar, A.; Bystersky, M.; Cadman, R. V.; Cai, X. Z.; Caines, H.; Sánchez, M. Calderón De La Barca; Castillo, J.; Catu, O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, H. A.; Christie, W.; Coffin, J. P.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Das, S.; Daugherity, M.; Moura, M. M. De; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; Didenko, L.; Dietel, T.; Dogra, S. M.; Dong, W. J.; Dong, X.; Draper, J. E.; Du, F.; Dubey, A. K.; Dunin, V. B.; Dunlop, J. C.; Mazumdar, M. R. Dutta; Eckardt, V.; Edwards, W. R.; Efimov, L. G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fornazier, K. S. F.; Fu, J.; Gagliardi, C. A.; Gaillard, L.; Gans, J.; Ganti, M. S.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J. E.; Gos, H.; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, S. M.; Guo, Y.; Gupta, A.; Gupta, N.; Gutierrez, T. D.; Hallman, T. J.; Hamed, A.; Hardtke, D.; Harris, J. W.; Heinz, M.; Henry, T. W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G. W.; Horner, M. J.; Huang, H. Z.; Huang, S. L.; Hughes, E. W.; Humanic, T. J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W. W.; Jedynak, M.; Jiang, H.; Jones, P. G.; Judd, E. G.; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Kechechyan, A.; Khodyrev, V. Yu.; Kim, B. C.; Kiryluk, J.; Kisiel, A.; Kislov, E. M.; Klay, J.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kowalik, K. L.; Kramer, M.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Kuhn, C.; Kulikov, A. I.; Kumar, A.; Kutuev, R. Kh.; Kuznetsov, A. A.; Lamont, M. A. C.; Landgraf, J. M.; Lange, S.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Lehocka, S.; Levine, M. J.; Li, C.; Li, Q.; Li, Y.; Lin, G.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Liu, Q. J.; Liu, Z.; Ljubicic, T.; Llope, W. J.; Long, H.; Longacre, R. S.; Lopez-Noriega, M.; Love, W. A.; Lu, Y.; Ludlam, T.; Lynn, D.; Ma, G. L.; Ma, J. G.; Ma, Y. G.; Magestro, D.; Mahajan, S.; Mahapatra, D. P.; Majka, R.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Martin, L.; Marx, J. N.; Matis, H. S.; Matulenko, Yu. A.; McClain, C. J.; McShane, T. S.; Meissner, F.; Melnick, Yu.; Meschanin, A.; Miller, M. L.; Minaev, N. G.; Mironov, C.; Mischke, A.; Mishra, D. K.; Mitchell, J.; Mohanty, B.; Molnar, L.; Moore, C. F.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nayak, S. K.; Nayak, T. K.; Nelson, J. M.; Netrakanti, P. K.; Nikitin, V. A.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okorokov, V.; Oldenburg, M.; Olson, D.; Pal, S. K.; Panebratsev, Y.; Panitkin, S. Y.; Pavlinov, A. I.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Petrov, V. A.; Phatak, S. C.; Picha, R.; Planinic, M.; Pluta, J.; Porile, N.; Porter, J.; Poskanzer, A. M.; Potekhin, M.; Potrebenikova, E.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Putschke, J.; Rakness, G.; Raniwala, R.; Raniwala, S.; Ravel, O.; Ray, R. L.; Razin, S. V.; Reichhold, D.; Reid, J. G.; Reinnarth, J.; Renault, G.; Retiere, F.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Sahoo, R.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarsour, M.; Savin, I.; Sazhin, P. S.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Schweda, K.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shahaliev, E.; Shao, M.; Shao, W.; Sharma, M.; Shen, W. Q.; Shestermanov, K. E.; Shimanskiy, S. S.; Sichtermann, E.; Simon, F.; Singaraju, R. N.; Smirnov, N.; Snellings, R.; Sood, G.; Sorensen, P.; Sowinski, J.; Speltz, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, T. D. S.; Stock, R.; Stolpovsky, A.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Sugarbaker, E.; Sumbera, M.; Surrow, B.; Swanger, M.; Symons, T. J. M.; Toledo, A. Szanto De; Tai, A.; Takahashi, J.; Tang, A. H.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Timmins, A. R.; Timoshenko, S.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; Buren, G. Van; Kolk, N. Van Der; Leeuwen, M. Van; Molen, A. M. Vander; Varma, R.; Vasilevski, I. M.; Vasiliev, A. N.; Vernet, R.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Waggoner, W. T.; Wang, F.; Wang, G.; Wang, G.; Wang, X. L.; Wang, Y.; Wang, Y.; Wang, Z. M.; Ward, H.; Watson, J. W.; Webb, J. C.; Westfall, G. D.; Wetzler, A.; Whitten, C., Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wood, J.; Wu, J.; Xu, N.; Xu, Z.; Xu, Z. Z.; Yamamoto, E.; Yepes, P.; Yoo, I.-K.; Yurevich, V. I.; Zborovsky, I.; Zhang, H.; Zhang, W. M.; Zhang, Y.; Zhang, Z. P.; Zhong, C.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zubarev, A. N.; Zuo, J. X.

    2006-03-01

    We present the directed flow (v1) measured in Au+Au collisions at sNN=62.4 GeV in the midpseudorapidity region |η|<1.3 and in the forward pseudorapidity region 2.5<|η|<4.0. The results are obtained using the three-particle cumulant method, the event plane method with mixed harmonics, and for the first time at the Relativistic Heavy Ion Collider, the standard method with the event plane reconstructed from spectator neutrons. Results from all three methods are in good agreement. Over the pseudorapidity range studied, charged particle directed flow is in the direction opposite to that of fragmentation neutrons.

  2. Nanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Bertoni, Giovanni; Fabbri, Filippo; Villani, Marco; Lazzarini, Laura; Turner, Stuart; van Tendeloo, Gustaaf; Calestani, Davide; Gradečak, Silvija; Zappettini, Andrea; Salviati, Giancarlo

    2016-01-01

    Metallic nanoparticles can be used to enhance optical absorption or emission in semiconductors, thanks to a strong interaction of collective excitations of free charges (plasmons) with electromagnetic fields. Herein we present direct imaging at the nanoscale of plasmon-exciton coupling in Au/ZnO nanostructures by combining scanning transmission electron energy loss and cathodoluminescence spectroscopy and mapping. The Au nanoparticles (~30 nm in diameter) are grown in-situ on ZnO nanotetrapods by means of a photochemical process without the need of binding agents or capping molecules, resulting in clean interfaces. Interestingly, the Au plasmon resonance is localized at the Au/vacuum interface, rather than presenting an isotropic distribution around the nanoparticle. On the contrary, a localization of the ZnO signal has been observed inside the Au nanoparticle, as also confirmed by numerical simulations.

  3. Nanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticles.

    PubMed

    Bertoni, Giovanni; Fabbri, Filippo; Villani, Marco; Lazzarini, Laura; Turner, Stuart; Van Tendeloo, Gustaaf; Calestani, Davide; Gradečak, Silvija; Zappettini, Andrea; Salviati, Giancarlo

    2016-01-01

    Metallic nanoparticles can be used to enhance optical absorption or emission in semiconductors, thanks to a strong interaction of collective excitations of free charges (plasmons) with electromagnetic fields. Herein we present direct imaging at the nanoscale of plasmon-exciton coupling in Au/ZnO nanostructures by combining scanning transmission electron energy loss and cathodoluminescence spectroscopy and mapping. The Au nanoparticles (~30 nm in diameter) are grown in-situ on ZnO nanotetrapods by means of a photochemical process without the need of binding agents or capping molecules, resulting in clean interfaces. Interestingly, the Au plasmon resonance is localized at the Au/vacuum interface, rather than presenting an isotropic distribution around the nanoparticle. On the contrary, a localization of the ZnO signal has been observed inside the Au nanoparticle, as also confirmed by numerical simulations. PMID:26754789

  4. Nanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticles

    PubMed Central

    Bertoni, Giovanni; Fabbri, Filippo; Villani, Marco; Lazzarini, Laura; Turner, Stuart; Van Tendeloo, Gustaaf; Calestani, Davide; Gradečak, Silvija; Zappettini, Andrea; Salviati, Giancarlo

    2016-01-01

    Metallic nanoparticles can be used to enhance optical absorption or emission in semiconductors, thanks to a strong interaction of collective excitations of free charges (plasmons) with electromagnetic fields. Herein we present direct imaging at the nanoscale of plasmon-exciton coupling in Au/ZnO nanostructures by combining scanning transmission electron energy loss and cathodoluminescence spectroscopy and mapping. The Au nanoparticles (~30 nm in diameter) are grown in-situ on ZnO nanotetrapods by means of a photochemical process without the need of binding agents or capping molecules, resulting in clean interfaces. Interestingly, the Au plasmon resonance is localized at the Au/vacuum interface, rather than presenting an isotropic distribution around the nanoparticle. On the contrary, a localization of the ZnO signal has been observed inside the Au nanoparticle, as also confirmed by numerical simulations. PMID:26754789

  5. Synthesis and optical property characterization of elongated AuPt and Pt@Au metal nanoframes

    NASA Astrophysics Data System (ADS)

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Hong, Soonchang; Moh, Sang Hyun; Park, Sungho

    2016-02-01

    We report a facile method to synthesize elongated nanoframes consisting of Pt and Au in solution. Pentagonal Au nanorods served as templates and successfully led to an elongated AuPt nanoframe after etching the core Au. Subsequently, the coating of Au around Pt ridges resulted in Pt@Au metal nanoframes. The resulting elongated nanostructure exhibited 5 well-defined ridges continuously connected along the long axis. During the shape evolution from pure Au nanorods to elongated Pt@Au metal nanoframes, their corresponding localized surface plasmon resonance bands were monitored. Especially, unique surface plasmon features were observed for elongated Pt@Au nanoframes where the short-axis oscillation of surface free electrons is strongly coupled but the long-axis oscillation is not coupled among the ridges.We report a facile method to synthesize elongated nanoframes consisting of Pt and Au in solution. Pentagonal Au nanorods served as templates and successfully led to an elongated AuPt nanoframe after etching the core Au. Subsequently, the coating of Au around Pt ridges resulted in Pt@Au metal nanoframes. The resulting elongated nanostructure exhibited 5 well-defined ridges continuously connected along the long axis. During the shape evolution from pure Au nanorods to elongated Pt@Au metal nanoframes, their corresponding localized surface plasmon resonance bands were monitored. Especially, unique surface plasmon features were observed for elongated Pt@Au nanoframes where the short-axis oscillation of surface free electrons is strongly coupled but the long-axis oscillation is not coupled among the ridges. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08200e

  6. K(892)* resonance production in Au+Au and p+p collisions at {radical}s{sub NN} = 200 GeV at RHIC

    SciTech Connect

    Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bharadwaj, S.; Bhasin, A.; Bhati, A.K.; Bhatia, V.S.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; de Moura, M.M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faivre, J.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fomenko, K.; Fu, J.; Gagliardi, C.A.; Gaillard, L.; Gans, J.; Ganti, M.S.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guo, Y.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kaplan, M.; Keane, D.; Khodyrev, V.Yu.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klay, J.; Klein, S.R.; Koetke, D.D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kramer, M.; Kravtsov, P.; Kravtsov, V.I.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; Kutuev, R.Kh.; et al.

    2004-12-09

    The short-lived K(892)* resonance provides an efficient tool to probe properties of the hot and dense medium produced in relativistic heavy-ion collisions. We report measurements of K* in {radical}s{sub NN} = 200 GeV Au+Au and p+p collisions reconstructed via its hadronic decay channels K(892)*{sup 0} {yields} K{pi} and K(892)*{sup +-} {yields} K{sub S}{sup 0}{pi}{sup +-} using the STAR detector at RHIC. The K*{sup 0} mass has been studied as function of p{sub T} in minimum bias p + p and central Au+Au collisions. The K* p{sub T} spectra for minimum bias p + p interactions and for Au+Au collisions in different centralities are presented. The K*/K ratios for all centralities in Au+Au collisions are found to be significantly lower than the ratio in minimum bias p + p collisions, indicating the importance of hadronic interactions between chemical and kinetic freeze-outs. The nuclear modification factor of K* at intermediate p{sub T} is similar to that of K{sub S}{sup 0}, but different from {Lambda}. This establishes a baryon-meson effect over a mass effect in the particle production at intermediate p{sub T} (2 < p{sub T} {le} 4 GeV/c). A significant non-zero K*{sup 0} elliptic flow (v{sub 2}) is observed in Au+Au collisions and compared to the K{sub S}{sup 0} and {Lambda} v{sub 2}.

  7. Information Presentation

    NASA Technical Reports Server (NTRS)

    Holden, Kritina; Sandor, A.; Thompson, S. G.; McCann, R. S.; Kaiser, M. K.; Begault, D. R.; Adelstein, B. D.; Beutter, B. R.; Stone, L. S.

    2008-01-01

    The goal of the Information Presentation Directed Research Project (DRP) is to address design questions related to the presentation of information to the crew on flight vehicles, surface landers and habitats, and during extra-vehicular activities (EVA). Designers of displays and controls for exploration missions must be prepared to select the text formats, label styles, alarms, electronic procedure designs, and cursor control devices that provide for optimal crew performance on exploration tasks. The major areas of work, or subtasks, within the Information Presentation DRP are: 1) Controls, 2) Displays, 3) Procedures, and 4) EVA Operations.

  8. Conservation Presentation.

    ERIC Educational Resources Information Center

    Friday, Gerald

    2001-01-01

    Introduces a project in which students teach about the importance of recycling and conservation by presenting demonstrations. Includes demonstrations on water, plastic, and other recycling products such as steel. (YDS)

  9. Delivery presentations

    MedlinePlus

    ... brow first position. Most of the time, the force of contractions causes the baby to be in face-first position. It is also detected when labor does not progress. In some of these presentations, ...

  10. Information Presentation

    NASA Technical Reports Server (NTRS)

    Holden, K.L.; Boyer, J.L.; Sandor, A.; Thompson, S.G.; McCann, R.S.; Begault, D.R.; Adelstein, B.D.; Beutter, B.R.; Stone, L.S.

    2009-01-01

    The goal of the Information Presentation Directed Research Project (DRP) is to address design questions related to the presentation of information to the crew. The major areas of work, or subtasks, within this DRP are: 1) Displays, 2) Controls, 3) Electronic Procedures and Fault Management, and 4) Human Performance Modeling. This DRP is a collaborative effort between researchers at Johnson Space Center and Ames Research Center.

  11. Rational design and synthesis of excavated trioctahedral Au nanocrystals

    NASA Astrophysics Data System (ADS)

    Chen, Qiaoli; Jia, Yanyan; Shen, Wei; Xie, Shuifen; Yang, Yanan; Cao, Zhenming; Xie, Zhaoxiong; Zheng, Lansun

    2015-06-01

    Excavated polyhedral nanostructures, possessing the features of high surface area and well-defined surface structure with a specific crystal facet and avoidance of aggregation, could be one of the best choices for the purpose of reducing consumption and improving performance of noble metals in many application fields. However, the formation of the excavated structures is thermodynamically unfavourable and its rational synthesis is far beyond our knowledge. In this work, taking overgrowth of Pd onto trioctahedral Au nanocrystals as a model, we present a deep insight study for synthesizing an excavated structure relying on the protection role of surfactants under suitable crystal growth kinetics. Based on the abovementioned understanding, we designed a simple and effective strategy to synthesize Au nanocrystals with excavated trioctahedral structure in one step. Due to the novel feature of the excavated structure and exposed high energy {110} facets, excavated trioctahedral Au NCs exhibited optical extinction at the near-infrared region and showed high catalytic activity towards the reduction of p-nitrophenol. Moreover, the synthetic strategy can be extended to the synthesis of excavated Au-Pd alloys.Excavated polyhedral nanostructures, possessing the features of high surface area and well-defined surface structure with a specific crystal facet and avoidance of aggregation, could be one of the best choices for the purpose of reducing consumption and improving performance of noble metals in many application fields. However, the formation of the excavated structures is thermodynamically unfavourable and its rational synthesis is far beyond our knowledge. In this work, taking overgrowth of Pd onto trioctahedral Au nanocrystals as a model, we present a deep insight study for synthesizing an excavated structure relying on the protection role of surfactants under suitable crystal growth kinetics. Based on the abovementioned understanding, we designed a simple and effective

  12. Geology, Geochemistry and Geophysics of Sedimentary Rock-Hosted Au Deposits in P.R. China

    USGS Publications Warehouse

    Peters, Stephen G.

    2002-01-01

    This is the second report concerning results of a joint project between the U.S. Geological Survey and the Tianjin Geological Academy to study sedimentary rock-hosted Au deposits in P.R. China. Since the 1980s, Chinese geologists have devoted a large-scale exploration and research effort to the deposits. As a result, there are more than 20 million oz of proven Au reserves in sedimentary rock-hosted Au deposits in P.R. China. Additional estimated and inferred resources are present in over 160 deposits and occurrences, which are undergoing exploration. This makes China second to Nevada in contained ounces of Au in Carlin-type deposits. It is likely that many of the Carlin-type Au ore districts in China, when fully developed, could have resource potential comparable to the multi-1,000-tonne Au resource in northern Nevada. The six chapters of this report describe sedimentary rock-hosted Au deposits that were visited during the project. Chapters 1 and 2 provide an overview of sedimentary rock-hosted Au deposits and Carlin-type Au deposits and also provide a working classification for the sedimentary rock-hosted Au deposits. Chapters 3, 4, and 5 provide descriptions that were compiled from the literature in China in three main areas: the Dian-Qian-Gui, the Qinling fold belt, and Middle-Lower Yangtze River areas. Chapter 6 contains a weights-of-evidence (WofE), GIS-based mineral assessment of sedimentary rock-hosted Au deposits in the Qinling fold belt and Dian-Qian-Gui areas. Appendices contain scanned aeromagnetic (Appendix I) and gravity (Appendix II) geophysical maps of south and central China. Data tables of the deposits (Appendix III) also are available in the first report as an interactive database at http://geopubs.wr.usgs.gov/open-file/of98-466/. Geochemical analysis of ore samples from the deposits visited are contained in Appendix IV.

  13. [Scientific presentation].

    PubMed

    Kraft, Giuliano

    2002-01-01

    To give a correct and effective scientific presentation, is an arduous task that asks for close examination of basic techniques of communication. This article proposes indications and suggestions to help public speakers to be communicators, to use visual aids and it explains how to capture the audience attention. PMID:12599721

  14. Wetting and energetics of solid Au and Au-Ge/SiC interfaces

    SciTech Connect

    Wang, Z.; Wynblatt, P.

    1998-09-01

    A solid state wetting technique has been used to investigate the effects of alloying Au with Ge on the wetting and energetics of Au/SiC interfaces at 1123 K. Germanium was found to segregate to the Au/SiC interface, thereby lowering the contact angle of Au on SiC from 133 to 110, and doubling the work of adhesion of Au on SiC. Calculations based on a monolayer model predict a segregation of 0.89 monolayers of Ge at the Au/SiC interface for Au containing 2.3 at.% Ge. This agrees reasonably well with a coverage of 0.6 monolayers Ge at the Au/SiC interface obtained by direct measurements based on the crater edge profiling technique. The work also demonstrates that simple models of interfacial composition can be combined with the Gibbs adsorption isotherm to provide reliable estimates of interfacial composition at complex four-component interfaces.

  15. Gold nanowired: a linear (Au25)(n) polymer from Au25 molecular clusters.

    PubMed

    De Nardi, Marco; Antonello, Sabrina; Jiang, De-en; Pan, Fangfang; Rissanen, Kari; Ruzzi, Marco; Venzo, Alfonso; Zoleo, Alfonso; Maran, Flavio

    2014-08-26

    Au25(SR)18 has provided fundamental insights into the properties of clusters protected by monolayers of thiolated ligands (SR). Because of its ultrasmall core, 1 nm, Au25(SR)18 displays molecular behavior. We prepared a Au25 cluster capped by n-butanethiolates (SBu), obtained its structure by single-crystal X-ray crystallography, and studied its properties both experimentally and theoretically. Whereas in solution Au25(SBu)18(0) is a paramagnetic molecule, in the crystal it becomes a linear polymer of Au25 clusters connected via single Au-Au bonds and stabilized by proper orientation of clusters and interdigitation of ligands. At low temperature, [Au25(SBu)18(0)]n has a nonmagnetic ground state and can be described as a one-dimensional antiferromagnetic system. These findings provide a breakthrough into the properties and possible solid-state applications of molecular gold nanowires. PMID:25088331

  16. Pt{sub 3}Au and PtAu clusters: Electronic states and potential energy surfaces

    SciTech Connect

    Dai, D.; Balasubramanian, K.

    1994-03-15

    We carried out complete active space multiconfiguration self-consistent-field calculations followed by multireference singles+doubles configuration interaction with the Davidson correction which included up to 3.55 million configurations employing relativistic effective core potentials on Pt{sub 3}+Au and PtAu clusters. Four low-lying electronic states were identified for Pt{sub 3}+Au. The {sup 2}{ital A}{sub 2} electronic state ({ital C}{sub 3{ital v}}) was found to be the ground state of Pt{sub 3}Au. Spin--orbit effects were found to be significant. We also computed six low-lying electronic states of PtAu and four low-lying electronic states of PtAu{sup +}. The 5/2 ({sup 2}{Delta}) and 0{sup +}({sup 1}{Sigma}{sup +}) states were found to be the ground states of PtAu and PtAu{sup +}, respectively.

  17. Ultrafast synthesis of Au(I)-dodecanethiolate nanotubes for advanced Hg2+ sensor electrodes

    PubMed Central

    2014-01-01

    In this work, an ultrafast and facile method is developed to synthesize Au(I)-dodecanethiolate nanotubes (Au(I)NTs) with the assistance of glycyl-glycyl-glycine (G-G-G). Transmission electron microscopy (TEM) images reveal that the as-prepared Au(I)NTs can be obtained in a 2-h reaction instead of a previous 24-h reaction and are uniform with a hollow structure and smooth surface by virtue of the G-G-G peptide tubular template. According to structural analysis, a possible preparative mechanism is proposed that the G-G-G peptide could help to curl into tube-like morphology in alkaline situation spontaneously to accelerate the formation of Au(I)NTs. Meanwhile, PVDF-stabilized Au(I)NT-modified glassy carbon electrodes present their promising potential for Hg2+ detection. PMID:25392708

  18. Nanoscale mapping of plasmon and exciton in ZnO tetrapods coupled with Au nanoparticles

    DOE PAGESBeta

    Bertoni, Giovanni; Fabbri, Filippo; Villani, Marco; Lazzarini, Laura; Turner, Stuart; Van Tendeloo, Gustaaf; Calestani, Davide; Gradečak, Silvija; Zappettini, Andrea; Salviati, Giancarlo

    2016-01-12

    Metallic nanoparticles can be used to enhance optical absorption or emission in semiconductors, thanks to a strong interaction of collective excitations of free charges (plasmons) with electromagnetic fields. Herein we present direct imaging at the nanoscale of plasmon-exciton coupling in Au/ZnO nanostructures by combining scanning transmission electron energy loss and cathodoluminescence spectroscopy and mapping. The Au nanoparticles (~30 nm in diameter) are grown in-situ on ZnO nanotetrapods by means of a photochemical process without the need of binding agents or capping molecules, resulting in clean interfaces. Interestingly, the Au plasmon resonance is localized at the Au/vacuum interface, rather than presentingmore » an isotropic distribution around the nanoparticle. Moreover, on the contrary, a localization of the ZnO signal has been observed inside the Au nanoparticle, as also confirmed by numerical simulations.« less

  19. Ultrafast synthesis of Au(I)-dodecanethiolate nanotubes for advanced Hg(2+) sensor electrodes.

    PubMed

    Zhang, Zhiqiang; Ma, Congcong; He, Lian; Zhu, Shijin; Hao, Xiaodong; Xie, Wanyi; Zhang, Wei; Zhang, Yuxin

    2014-01-01

    In this work, an ultrafast and facile method is developed to synthesize Au(I)-dodecanethiolate nanotubes (Au(I)NTs) with the assistance of glycyl-glycyl-glycine (G-G-G). Transmission electron microscopy (TEM) images reveal that the as-prepared Au(I)NTs can be obtained in a 2-h reaction instead of a previous 24-h reaction and are uniform with a hollow structure and smooth surface by virtue of the G-G-G peptide tubular template. According to structural analysis, a possible preparative mechanism is proposed that the G-G-G peptide could help to curl into tube-like morphology in alkaline situation spontaneously to accelerate the formation of Au(I)NTs. Meanwhile, PVDF-stabilized Au(I)NT-modified glassy carbon electrodes present their promising potential for Hg(2+) detection. PMID:25392708

  20. Electrical performance of Ti-ZnO-Au thin film composite structure for device application

    NASA Astrophysics Data System (ADS)

    Joshi, Priyanka; Singh, Jitendra; Das, Surajit; Desai, J. V.; Akhtar, Jamil

    2016-04-01

    Thin film layers of Au/Ti approximately 2200 Å thick and ZnO approximately 2.24 µm thick were sputtered sequentially onto silicon dioxide coated <100> Si-wafer. Conventional wisdom confirms the adhesion of gold over zinc oxide (ZnO) by an intermediate layer of titanium for better adhesion. But, in Au/Ti/ZnO/Au/Ti structure, it was observed that with the passing of time the gold diffused into ZnO thin film at room temperature, making a very low resistance between the two gold layers eventually making a conductive path in ZnO. Therefore, electrical connectivity was found between the metal layers. A detailed experimental analysis has been carried out in support of the observed Au diffusion. In the present work, reliability of Ti/Au metallisation and anomalous electrical behavior due to gold diffusion has been studied.

  1. Interplanetary dust between 1 and 5 AU

    NASA Technical Reports Server (NTRS)

    Stanley, J. E.; Singer, S. F.; Alvarez, J. M.

    1979-01-01

    Analyses of data from the Meteoroid Detection Experiment (MDE) and the Imaging Photopolarimeter (IPP) aboard Pioneer 10 and 11 have led to contradictory conclusions. While the MDE indicates a significant particle environment in the outer solar system (out to at least 5 AU), the IPP sees no zodiacal light (therefore implying no small particles) past 3.3 AU. These two results are reconciled by noting that the spectral index p (relating particle radius and particle concentration) is not a constant in the solar system but changes from less than 2 near 1 AU to more than 2.5 at 5 AU for particles in the range of 10 microns.

  2. Overview Presentation

    NASA Technical Reports Server (NTRS)

    Lytle, John

    2001-01-01

    This report provides an overview presentation of the 2000 NPSS (Numerical Propulsion System Simulation) Review and Planning Meeting. Topics include: 1) a background of the program; 2) 1999 Industry Feedback; 3) FY00 Status, including resource distribution and major accomplishments; 4) FY01 Major Milestones; and 5) Future direction for the program. Specifically, simulation environment/production software and NPSS CORBA Security Development are discussed.

  3. Solid-State Synthesized Nanostructured Au Dendritic Aggregates Towards Surface-Enhanced Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Gentile, A.; Ruffino, F.; D'Andrea, C.; Gucciardi, P. G.; Reitano, R.; Grimaldi, M. G.

    2016-06-01

    Micrometric Au structures, presenting a dendritic nano-structure, have been fabricated on a Si-based substrate. The fabrication method involves the deposition of a thin Au film on the substrate and a high-temperature annealing (1100°C) using fast heating and cooling ramps. The thermal process produces the growth, from the substrate, of Si micro-pillars whose top surfaces, covered by a crystalline Au layer, present a nanodendritic morphology. In addition to the micro-pillars, the sample surface presents a complex structural and chemical composition including Si3N4 regions due to the silicon-nitrogen intermixing during the heating stage. By studying the kinetic processes at the Au-Si interface during the thermal treatment, we describe the stages involved in the micro-pillars growth, in the dendritic morphology development, and in the Au atoms entrapment at the top of the dendritic surfaces. Finally, we present the analyses of the optical and surface enhanced Raman scattering properties of the Au dendritic aggregates. We show, in particular, that: (1) the Au dendrites aggregates act as effective scattering elements for the electromagnetic radiation in the infrared spectral region; and (2) the higher surface area due to the branched dendritic structure is responsible for the improvement in the sensitivity of the surface enhanced Raman scattering activity.

  4. Azimuthal anisotropy and correlations at large transverse momenta in p + p and Au + Au collisions at square root sNN=200 GeV.

    PubMed

    Adams, J; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Arkhipkin, D; Averichev, G S; Badyal, S K; Bai, Y; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bharadwaj, S; Bhasin, A; Bhati, A K; Bhatia, V S; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A V; Bravar, A; Bystersky, M; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Cebra, D; Chajecki, Z; Chaloupka, P; Chattopdhyay, S; Chen, H F; Chen, Y; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; de Moura, M M; Derevschikov, A A; Didenko, L; Dietel, T; Dogra, S M; Dong, W J; Dong, X; Draper, J E; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Mazumdar, M R; Eckardt, V; Edwards, W R; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Fachini, P; Faivre, J; Fatemi, R; Fedorisin, J; Filimonov, K; Filip, P; Finch, E; Fine, V; Fisyak, Y; Foley, K J; Fomenko, K; Fu, J; Gagliardi, C A; Gans, J; Ganti, M S; Gaudichet, L; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grebenyuk, O; Grosnick, D; Guertin, S M; Guo, Y; Gupta, A; Gutierrez, T D; Hallman, T J; Hamed, A; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Hepplemann, S; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Huang, H Z; Huang, S L; Hughes, E W; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Jiang, H; Jones, P G; Judd, E G; Kabana, S; Kang, K; Kaplan, M; Keane, D; Khodyrev, V Yu; Kiryluk, J; Kisiel, A; Kislov, E M; Klay, J; Klein, S R; Klyachko, A; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kramer, M; Kravtsov, P; Kravtsov, V I; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Laue, F; Lauret, J; Lebedev, A; Lednicky, R; Lehocka, S; LeVine, M J; Li, C; Li, Q; Li, Y; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Q J; Liu, Z; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Lu, Y; Ludlam, T; Lynn, D; Ma, G L; Ma, J G; Ma, Y G; Magestro, D; Mahajan, S; Mahapatra, D P; Majka, R; Mangotra, L K; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J N; Matis, H S; Matulenko, Yu A; McClain, C J; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mischke, A; Mishra, D K; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Morozov, D A; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Netrakanti, P K; Nikitin, V A; Nogach, L V; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Peitzmann, T; Perevoztchikov, V; Perkins, C; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Rose, A; Roy, C; Ruan, L; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Sazhin, P S; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seyboth, P; Shahaliev, E; Shao, M; Shao, W; Sharma, M; Shen, W Q; Shestermanov, K E; Shimanskiy, S S; Sichtermann, E; Simon, F; Singaraju, R N; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Speltz, J; Spinka, H M; Srivastava, B; Stadnik, A; Stanislaus, T D S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Tarnowsky, T; Thein, D; Thomas, J H; Timoshenko, S; Tokarev, M; Trentalange, S; Tribble, R E; Tsai, O D; Ulery, J; Ullrich, T; Underwood, D G; Urkinbaev, A; Van Buren, G; van Leeuwen, M; Vander Molen, A M; Varma, R; Vasilevski, I M; Vasiliev, A N; Vernet, R; Vigdor, S E; Viyogi, Y P; Vokal, S; Voloshin, S A; Vznuzdaev, M; Waggoner, W T; Wang, F; Wang, G; Wang, G; Wang, X L; Wang, Y; Wang, Y; Wang, Z M; Ward, H; Watson, J W; Webb, J C; Wells, R; Westfall, G D; Wetzler, A; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yamamoto, E; Yepes, P; Yurevich, V I; Zanevsky, Y V; Zhang, H; Zhang, W M; Zhang, Z P; Zolnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, Y; Zubarev, A N

    2004-12-17

    Results on high transverse momentum charged particle emission with respect to the reaction plane are presented for Au + Au collisions at square root s(NN)=200 GeV. Two- and four-particle correlations results are presented as well as a comparison of azimuthal correlations in Au + Au collisions to those in p + p at the same energy. The elliptic anisotropy v(2) is found to reach its maximum at p(t) approximately 3 GeV/c, then decrease slowly and remain significant up to p(t) approximately 7-10 GeV/c. Stronger suppression is found in the back-to-back high-p(t) particle correlations for particles emitted out of plane compared to those emitted in plane. The centrality dependence of v(2) at intermediate p(t) is compared to simple models based on jet quenching. PMID:15697893

  5. Improvement on electrical conductivity and electron field emission properties of Au-ion implanted ultrananocrystalline diamond films by using Au-Si eutectic substrates

    SciTech Connect

    Sankaran, K. J.; Sundaravel, B.; Tai, N. H. E-mail: inanlin@mail.tku.edu.tw; Lin, I. N. E-mail: inanlin@mail.tku.edu.tw

    2015-08-28

    In the present work, Au-Si eutectic layer was used to enhance the electrical conductivity/electron field emission (EFE) properties of Au-ion implanted ultrananocrystalline diamond (Au-UNCD) films grown on Si substrates. The electrical conductivity was improved to a value of 230 (Ω cm){sup −1}, and the EFE properties was enhanced reporting a low turn-on field of 2.1 V/μm with high EFE current density of 5.3 mA/cm{sup 2} (at an applied field of 4.9 V/μm) for the Au-UNCD films. The formation of SiC phase circumvents the formation of amorphous carbon prior to the nucleation of diamond on Si substrates. Consequently, the electron transport efficiency of the UNCD-to-Si interface increases, thereby improving the conductivity as well as the EFE properties. Moreover, the salient feature of these processes is that the sputtering deposition of Au-coating for preparing the Au-Si interlayer, the microwave plasma enhanced chemical vapor deposition process for growing the UNCD films, and the Au-ion implantation process for inducing the nanographitic phases are standard thin film preparation techniques, which are simple, robust, and easily scalable. The availability of these highly conducting UNCD films with superior EFE characteristics may open up a pathway for the development of high-definition flat panel displays and plasma devices.

  6. Improvement on electrical conductivity and electron field emission properties of Au-ion implanted ultrananocrystalline diamond films by using Au-Si eutectic substrates

    NASA Astrophysics Data System (ADS)

    Sankaran, K. J.; Sundaravel, B.; Tai, N. H.; Lin, I. N.

    2015-08-01

    In the present work, Au-Si eutectic layer was used to enhance the electrical conductivity/electron field emission (EFE) properties of Au-ion implanted ultrananocrystalline diamond (Au-UNCD) films grown on Si substrates. The electrical conductivity was improved to a value of 230 (Ω cm)-1, and the EFE properties was enhanced reporting a low turn-on field of 2.1 V/μm with high EFE current density of 5.3 mA/cm2 (at an applied field of 4.9 V/μm) for the Au-UNCD films. The formation of SiC phase circumvents the formation of amorphous carbon prior to the nucleation of diamond on Si substrates. Consequently, the electron transport efficiency of the UNCD-to-Si interface increases, thereby improving the conductivity as well as the EFE properties. Moreover, the salient feature of these processes is that the sputtering deposition of Au-coating for preparing the Au-Si interlayer, the microwave plasma enhanced chemical vapor deposition process for growing the UNCD films, and the Au-ion implantation process for inducing the nanographitic phases are standard thin film preparation techniques, which are simple, robust, and easily scalable. The availability of these highly conducting UNCD films with superior EFE characteristics may open up a pathway for the development of high-definition flat panel displays and plasma devices.

  7. Identified Baryon and Meson Distributions at Large Transverse Momenta from Au+Au Collisions at {radical}(s{sub NN})=200 GeV

    SciTech Connect

    Abelev, B. I.; Bielcik, J.; Bielcikova, J.; Caines, H.; Catu, O.; Chikanian, A.; Du, F.; Finch, E.; Harris, J. W.; Heinz, M.; Lamont, M. A. C.; Lin, G.; Majka, R.; Nattrass, C.; Salur, S.; Sandweiss, J.; Smirnov, N.; Witt, R.; Aggarwal, M. M.; Bhati, A. K.

    2006-10-13

    Transverse momentum spectra of {pi}{sup {+-}}, p, and p up to 12 GeV/c at midrapidity in centrality selected Au+Au collisions at {radical}(s{sub NN})=200 GeV are presented. In central Au+Au collisions, both {pi}{sup {+-}} and p(p) show significant suppression with respect to binary scaling at p{sub T}(greater-or-similar sign)4 GeV/c. Protons and antiprotons are less suppressed than {pi}{sup {+-}}, in the range 1.5 < or approx. p{sub T} < or approx. 6 GeV/c. The {pi}{sup -}/{pi}{sup +} and p/p ratios show at most a weak p{sub T} dependence and no significant centrality dependence. The p/{pi} ratios in central Au+Au collisions approach the values in p+p and d+Au collisions at p{sub T} > or approx. 5 GeV/c. The results at high p{sub T} indicate that the partonic sources of {pi}{sup {+-}}, p, and p have similar energy loss when traversing the nuclear medium.

  8. Identified baryon and meson distributions at large transverse momenta from Au + Au collisions at square root sNN=200 GeV.

    PubMed

    Abelev, B I; Aggarwal, M M; Ahammed, Z; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Bai, Y; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellingeri-Laurikainen, A; Bellwied, R; Benedosso, F; Bhardwaj, S; Bhasin, A; Bhati, A K; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Blyth, S-L; Bonner, B E; Botje, M; Bouchet, J; Brandin, A V; Bravar, A; Burton, T P; Bystersky, M; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Castillo, J; Catu, O; Cebra, D; Chajecki, Z; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, J H; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Coffin, J P; Cormier, T M; Cosentino, M R; Cramer, J G; Crawford, H J; Das, D; Das, S; Dash, S; Daugherity, M; de Moura, M M; Dedovich, T G; Dephillips, M; Derevschikov, A A; Didenko, L; Dietel, T; Djawotho, P; Dogra, S M; Dong, W J; Dong, X; Draper, J E; Du, F; Dunin, V B; Dunlop, J C; Dutta Mazumdar, M R; Eckardt, V; Edwards, W R; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Fachini, P; Fatemi, R; Fedorisin, J; Filip, P; Finch, E; Fine, V; Fisyak, Y; Fu, J; Gagliardi, C A; Gaillard, L; Ganti, M S; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Gorbunov, Y G; Gos, H; Grebenyuk, O; Grosnick, D; Guertin, S M; Guimaraes, K S F F; Gupta, N; Gutierrez, T D; Haag, B; Hallman, T J; Hamed, A; Harris, J W; He, W; Heinz, M; Henry, T W; Hepplemann, S; Hippolyte, B; Hirsch, A; Hjort, E; Hoffman, A M; Hoffmann, G W; Horner, M J; Huang, H Z; Huang, S L; Hughes, E W; Humanic, T J; Igo, G; Jacobs, P; Jacobs, W W; Jakl, P; Jia, F; Jiang, H; Jones, P G; Judd, E G; Kabana, S; Kang, K; Kapitan, J; Kaplan, M; Keane, D; Kechechyan, A; Khodyrev, V Yu; Kim, B C; Kiryluk, J; Kisiel, A; Kislov, E M; Klein, S R; Kocoloski, A; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kouchpil, V; Kowalik, K L; Kramer, M; Kravtsov, P; Kravtsov, V I; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lapointe, S; Laue, F; Lauret, J; Lebedev, A; Lednicky, R; Lee, C-H; Lehocka, S; Levine, M J; Li, C; Li, Q; Li, Y; Lin, G; Lin, X; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, H; Liu, J; Liu, L; Liu, Z; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Love, W A; Lu, Y; Ludlam, T; Lynn, D; Ma, G L; Ma, J G; Ma, Y G; Magestro, D; Mahapatra, D P; Majka, R; Mangotra, L K; Manweiler, R; Margetis, S; Markert, C; Martin, L; Matis, H S; Matulenko, Yu A; McClain, C J; McShane, T S; Melnick, Yu; Meschanin, A; Millane, J; Miller, M L; Minaev, N G; Mioduszewski, S; Mironov, C; Mischke, A; Mishra, D K; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Morozov, D A; Munhoz, M G; Nandi, B K; Nattrass, C; Nayak, T K; Nelson, J M; Nepali, N S; Netrakanti, P K; Nogach, L V; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Pachr, M; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Peitzmann, T; Perevoztchikov, V; Perkins, C; Peryt, W; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Poljak, N; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rakness, G; Raniwala, R; Raniwala, S; Ray, R L; Razin, S V; Reinnarth, J; Relyea, D; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Rose, A; Roy, C; Ruan, L; Russcher, M J; Sahoo, R; Sakuma, T; Salur, S; Sandweiss, J; Sarsour, M; Sazhin, P S; Schambach, J; Scharenberg, R P; Schmitz, N; Seger, J; Selyuzhenkov, I; Seyboth, P; Shabetai, A; Shahaliev, E; Shao, M; Sharma, M; Shen, W Q; Shimanskiy, S S; Sichtermann, E P; Simon, F; Singaraju, R N; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Speltz, J; Spinka, H M; Srivastava, B; Stadnik, A; Stanislaus, T D S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Suaide, A A P; Subba, N L; Sugarbaker, E; Sumbera, M; Sun, Z; Surrow, B; Swanger, M; Symons, T J M; Szanto de Toledo, A; Tai, A; Takahashi, J; Tang, A H; Tarnowsky, T; Thein, D; Thomas, J H; Timmins, A R; Timoshenko, S; Tokarev, M; Trainor, T A; Trentalange, S; Tribble, R E; Tsai, O D; Ulery, J; Ullrich, T; Underwood, D G; Van Buren, G; van der Kolk, N; van Leeuwen, M; Vander Molen, A M; Varma, R; Vasilevski, I M; Vasiliev, A N; Vernet, R; Vigdor, S E; Viyogi, Y P; Vokal, S; Voloshin, S A; Waggoner, W T; Wang, F; Wang, G; Wang, J S; Wang, X L; Wang, Y; Watson, J W; Webb, J C; Westfall, G D; Wetzler, A; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Q H; Xu, Z; Yepes, P; Yoo, I-K; Yurevich, V I; Zhan, W; Zhang, H; Zhang, W M; Zhang, Y; Zhang, Z P; Zhao, Y; Zhong, C; Zoulkarneev, R; Zoulkarneeva, Y; Zubarev, A N; Zuo, J X

    2006-10-13

    Transverse momentum spectra of pi+/-, p, and p up to 12 GeV/c at midrapidity in centrality selected Au + Au collisions at square root sNN=200 GeV are presented. In central Au + Au collisions, both pi +/- and p(p) show significant suppression with respect to binary scaling at pT approximately >4 GeV/c. Protons and antiprotons are less suppressed than pi+/-, in the range 1.5 approximately < pT approximately < 6 GeV/c. The pi-/pi+ and p/p ratios show at most a weak pT dependence and no significant centrality dependence. The p/pi ratios in central Au + Au collisions approach the values in p + p and d + Au collisions at pT approximately >5 GeV/c. The results at high pT indicate that the partonic sources of pi+/-, p, and p have similar energy loss when traversing the nuclear medium. PMID:17155321

  9. Gold surfaces and nanoparticles are protected by Au(0)–thiyl species and are destroyed when Au(I)–thiolates form

    PubMed Central

    Reimers, Jeffrey R.; Ford, Michael J.; Halder, Arnab; Ulstrup, Jens; Hush, Noel S.

    2016-01-01

    The synthetic chemistry and spectroscopy of sulfur-protected gold surfaces and nanoparticles is analyzed, indicating that the electronic structure of the interface is Au(0)–thiyl, with Au(I)–thiolates identified as high-energy excited surface states. Density-functional theory indicates that it is the noble character of gold and nanoparticle surfaces that destabilizes Au(I)–thiolates. Bonding results from large van der Waals forces, influenced by covalent bonding induced through s–d hybridization and charge polarization effects that perturbatively mix in some Au(I)–thiolate character. A simple method for quantifying these contributions is presented, revealing that a driving force for nanoparticle growth is nobleization, minimizing Au(I)–thiolate involvement. Predictions that Brust–Schiffrin reactions involve thiolate anion intermediates are verified spectroscopically, establishing a key feature needed to understand nanoparticle growth. Mixing of preprepared Au(I) and thiolate reactants always produces Au(I)–thiolate thin films or compounds rather than monolayers. Smooth links to O, Se, Te, C, and N linker chemistry are established. PMID:26929334

  10. ZnO-Au-SnO2 Z-scheme photoanodes for remarkable photoelectrochemical water splitting.

    PubMed

    Li, Jing-Mei; Cheng, Hao-Yun; Chiu, Yi-Hsuan; Hsu, Yung-Jung

    2016-08-25

    For the first time a ZnO nanorod-based Z-scheme heterostructure system was proposed and realized for efficient photoelectrochemical water splitting. The samples were prepared by depositing a thin layer of SnO2 on the Au surface of Au particle-decorated ZnO nanorods. For ZnO-Au-SnO2 nanorods, the embedded Au can mediate interfacial charge transfer by promoting electron transfer from the conduction band of SnO2 to the valence band of ZnO. This vectorial charge transfer resulted in the situation that the photoexcited electrons accumulated at ZnO while the photogenerated holes concentrated at SnO2, giving ZnO-Au-SnO2 substantially high redox powers. Time-resolved photoluminescence spectra suggested that the interfacial charge transfer across the ZnO/Au/SnO2 interface was significantly improved as a result of the Z-scheme charge transfer mechanism. With the substantially high redox powers and significantly improved interfacial charge transfer, ZnO-Au-SnO2 nanorods performed much better as a photoanode in photoelectrochemical water splitting than pristine ZnO, plasmonic Au-decorated ZnO and type-II SnO2-coated ZnO nanorods did. The present study has provided a viable approach to exploit Z-scheme photoanodes in the design of efficient artificial photosynthesis systems for solar energy conversion. PMID:27527337

  11. An X-ray Absorption Fine Structure study of Au adsorbed onto the non-metabolizing cells of two soil bacterial species

    SciTech Connect

    Song, Zhen; Kenney, Janice P.L.; Fein, Jeremy B.; Bunker, Bruce A.

    2015-02-09

    Gram-positive and Gram-negative bacterial cells can remove Au from Au(III)-chloride solutions, and the extent of removal is strongly pH dependent. In order to determine the removal mechanisms, X-ray Absorption Fine Structure (XAFS) spectroscopy experiments were conducted on non-metabolizing biomass of Bacillus subtilis and Pseudomonas putida with fixed Au(III) concentrations over a range of bacterial concentrations and pH values. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data on both bacterial species indicate that more than 90% of the Au atoms on the bacterial cell walls were reduced to Au(I). In contrast to what has been observed for Au(III) interaction with metabolizing bacterial cells, no Au(0) or Au-Au nearest neighbors were observed in our experimental systems. All of the removed Au was present as adsorbed bacterial surface complexes. For both species, the XAFS data suggest that although Au-chloride-hydroxide aqueous complexes dominate the speciation of Au in solution, Au on the bacterial cell wall is characterized predominantly by binding of Au atoms to sulfhydryl functional groups and amine and/or carboxyl functional groups, and the relative importance of the sulfhydryl groups increases with increasing pH and with decreasing Au loading. The XAFS data for both microorganism species suggest that adsorption is the first step in the formation of Au nanoparticles by bacteria, and the results enhance our ability to account for the behavior of Au in bacteria-bearing geologic systems.

  12. An X-ray Absorption Fine Structure study of Au adsorbed onto the non-metabolizing cells of two soil bacterial species

    NASA Astrophysics Data System (ADS)

    Song, Zhen; Kenney, Janice P. L.; Fein, Jeremy B.; Bunker, Bruce A.

    2012-06-01

    Gram-positive and Gram-negative bacterial cells can remove Au from Au(III)-chloride solutions, and the extent of removal is strongly pH dependent. In order to determine the removal mechanisms, X-ray Absorption Fine Structure (XAFS) spectroscopy experiments were conducted on non-metabolizing biomass of Bacillus subtilis and Pseudomonas putida with fixed Au(III) concentrations over a range of bacterial concentrations and pH values. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) data on both bacterial species indicate that more than 90% of the Au atoms on the bacterial cell walls were reduced to Au(I). In contrast to what has been observed for Au(III) interaction with metabolizing bacterial cells, no Au(0) or Au-Au nearest neighbors were observed in our experimental systems. All of the removed Au was present as adsorbed bacterial surface complexes. For both species, the XAFS data suggest that although Au-chloride-hydroxide aqueous complexes dominate the speciation of Au in solution, Au on the bacterial cell wall is characterized predominantly by binding of Au atoms to sulfhydryl functional groups and amine and/or carboxyl functional groups, and the relative importance of the sulfhydryl groups increases with increasing pH and with decreasing Au loading. The XAFS data for both microorganism species suggest that adsorption is the first step in the formation of Au nanoparticles by bacteria, and the results enhance our ability to account for the behavior of Au in bacteria-bearing geologic systems.

  13. Bright, NIR-emitting Au23 from Au25: characterization and applications including biolabeling.

    PubMed

    Muhammed, Madathumpady Abubaker Habeeb; Verma, Pramod Kumar; Pal, Samir Kumar; Kumar, R C Arun; Paul, Soumya; Omkumar, Ramakrishnapillai Vyomakesannair; Pradeep, Thalappil

    2009-10-01

    A novel interfacial route has been developed for the synthesis of a bright-red-emitting new subnanocluster, Au(23), by the core etching of a widely explored and more stable cluster, Au(25)SG(18) (in which SG is glutathione thiolate). A slight modification of this procedure results in the formation of two other known subnanoclusters, Au(22) and Au(33). Whereas Au(22) and Au(23) are water soluble and brightly fluorescent with quantum yields of 2.5 and 1.3 %, respectively, Au(33) is organic soluble and less fluorescent, with a quantum yield of 0.1 %. Au(23) exhibits quenching of fluorescence selectively in the presence of Cu(2+) ions and it can therefore be used as a metal-ion sensor. Aqueous- to organic-phase transfer of Au(23) has been carried out with fluorescence enhancement. Solvent dependency on the fluorescence of Au(23) before and after phase transfer has been studied extensively and the quantum yield of the cluster varies with the solvent used. The temperature response of Au(23) emission has been demonstrated. The inherent fluorescence of Au(23) was used for imaging human hepatoma cells by employing the avidin-biotin interaction. PMID:19711391

  14. The Electronic Properties and L3 XANES of Au and Nano-Au

    SciTech Connect

    Yiu, Y.M.; Zhang, P.; Sham, T.K.

    2004-04-20

    The electronic properties of Au crystal and nano Au have been investigated by theory and experiment. Molecularly capped nano-Au was synthesized using the two-phase method. Au nano-particles have been characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). They retain the fcc crystal structure. Their sizes have been determined to be in a range from 5.5 nm to 1.7 nm. The L3 X-ray Absorption Near Edge Structure (XANES) of nano-Au and Au foil have been recorded using synchrotron radiation, and examined by theoretical calculation based on the first principles. Both theory and experiment show that the nano-Au particles have essentially all the Au L3 XANES features of bulk Au in the near edge region with less pronounced resonance peaks. It is also shown that nano Au exhibits lower 4f binding energy than bulk Au in good agreement with quantum confined Au systems reported previously.

  15. Neutral Pion Production in Au+Au Collisions at sqrt sNN = 200 GeV

    SciTech Connect

    STAR Collaboration; Abelev, B. I.

    2009-10-23

    The results of mid-rapidity (0 < y < 0.8) neutral pion spectra over an extended transverse momentum range (1 < p{sub T} < 12 GeV/c) in {radical}s{sub NN} = 200 GeV Au+Au collisions, measured by the STAR experiment, are presented. The neutral pions are reconstructed from photons measured either by the STAR Barrel Electro-Magnetic Calorimeter (BEMC) or by the Time Projection Chamber (TPC) via tracking of conversion electron-positron pairs. Our measurements are compared to previously published {pi}{sup {+-}} and {pi}{sup 0} results. The nuclear modification factors R{sub CP} and R{sub AA} of {pi}{sup 0} are also presented as a function of p{sub T}. In the most central Au+Au collisions, the binary collision scaled {pi}{sup 0} yield at high p{sub T} is suppressed by a factor of about 5 compared to the expectation from the yield of p+p collisions. Such a large suppression is in agreement with previous observations for light quark mesons and is consistent with the scenario that partons suffer considerable energy loss in the dense medium formed in central nucleus-nucleus collisions at RHIC.

  16. Numerical simulations of high-speed solar wind streams within 1 AU and their signatures at 1 AU

    NASA Technical Reports Server (NTRS)

    Smith, Z.; Dryer, M.

    1991-01-01

    A parametric study of the evolution within, and signatures at, 1 AU of high-speed streams is performed with the use of a MHD two-and-a-half-dimensional time-dependent model. This study is an extension of an earlier one by Smith and Dryer (1990) who examined the ecliptic plane consequences of relatively short-duration, energetic solar disturbances. The present study examines both the erupting and corotating parts of long-duration, high-speed streams characteristic of coronal hole flows. By examining the variation of the simulated plasma velocity, density, temperature, and magnetic field at 1 AU, as well as the location of the solar coronal hole sources relative to the observer at 1 AU, it was possible to provide some insight into the identification of the solar sources of interplanetary disturbances. Two definitions for angle locating the solar source of interplanetary disturbances at 1 AU are presented and discussed. The results are applied to the suggestion by Hewish (1988) that low-latitude coronal holes are suitably positioned to be the sources of major geomagnetic storms when the holes are in the eastern half of the solar hemisphere at the time of the commencement of the storm. The results indicate that, for these cases, the streams emanating from within the hole must be very fast, greater than 1000 km/s, or very wide, greater than 60 deg, at the inner boundary of 18 solar radii.

  17. Centrality dependence of charged particle multiplicity in Au-Au collisions at square root of (s)NN = 130 GeV.

    PubMed

    Adcox, K; Adler, S S; Ajitanand, N N; Akiba, Y; Alexander, J; Aphecetche, L; Arai, Y; Aronson, S H; Averbeck, R; Awes, T C; Barish, K N; Barnes, P D; Barrette, J; Bassalleck, B; Bathe, S; Baublis, V; Bazilevsky, A; Belikov, S; Bellaiche, F G; Belyaev, S T; Bennett, M J; Berdnikov, Y; Botelho, S; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J; Butsyk, S; Carey, T A; Chand, P; Chang, J; Chang, W C; Chavez, L L; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choudhury, R K; Christ, T; Chujo, T; Chung, M S; Chung, P; Cianciolo, V; Cole, B A; D'Enterria, D G; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dinesh, B V; Drees, A; Durum, A; Dutta, D; Ebisu, K; Efremenko, Y V; El Chenawi, K; En'yo, H; Esumi, S; Ewell, L; Ferdousi, T; Fields, D E; Fokin, S L; Fraenkel, Z; Franz, A; Frawley, A D; Fung, S Y; Garpman, S; Ghosh, T K; Glenn, A; Godoi, A L; Goto, Y; Greene, S V; Grosse Perdekamp, M; Gupta, S K; Guryn, W; Gustafsson, H A; Haggerty, J S; Hamagaki, H; Hansen, A G; Hara, H; Hartouni, E P; Hayano, R; Hayashi, N; He, X; Hemmick, T K; Heuser, J; Hibino, M; Hill, J C; Ho, D S; Homma, K; Hong, B; Hoover, A; Ichihara, T; Imai, K; Ippolitov, M S; Ishihara, M; Jacak, B V; Jang, W Y; Jia, J; Johnson, B M; Johnson, S C; Joo, K S; Kametani, S; Kang, J H; Kann, M; Kapoor, S S; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D J; Kim, H J; Kim, S Y; Kim, Y G; Kinnison, W W; Kistenev, E; Kiyomichi, A; Klein-Boesing, C; Klinksiek, S; Kochenda, L; Kochetkov, D; Kochetkov, V; Koehler, D; Kohama, T; Kozlov, A; Kroon, P J; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Lauret, J; Lebedev, A; Lee, D M; Leitch, M J; Li, X H; Li, Z; Lim, D J; Liu, M X; Liu, X; Liu, Z; Maguire, C F; Mahon, J; Makdisi, Y I; Manko, V I; Mao, Y; Mark, S K; Markacs, S; Martinez, G; Marx, M D; Masaike, A; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E; Merschmeyer, M; Messer, F; Messer, M; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mühlbacher, F; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagasaka, Y; Nagle, J L; Nakada, Y; Nandi, B K; Newby, J; Nikkinen, L; Nilsson, P; Nishimura, S; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Ono, M; Onuchin, V; Oskarsson, A; Osterman, L; Otterlund, I; Oyama, K; Paffrath, L; Palounek, A P; Pantuev, V S; Papavassiliou, V; Pate, S F; Peitzmann, T; Petridis, A N; Pinkenburg, C; Pisani, R P; Pitukhin, P; Plasil, F; Pollack, M; Pope, K; Purschke, M L; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Rosati, M; Rose, A A; Ryu, S S; Saito, N; Sakaguchi, A; Sakaguchi, T; Sako, H; Sakuma, T; Samsonov, V; Sangster, T C; Santo, R; Sato, H D; Sato, S; Sawada, S; Schlei, B R; Schutz, Y; Semenov, V; Seto, R; Shea, T K; Shein, I; Shibata, T A; Shigaki, K; Shiina, T; Shin, Y H; Sibiriak, I G; Silvermyr, D; Sim, K S; Simon-Gillo, J; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sorensen, S; Stankus, P W; Starinsky, N; Steinberg, P; Stenlund, E; Ster, A; Stoll, S P; Sugioka, M; Sugitate, T; Sullivan, J P; Sumi, Y; Sun, Z; Suzuki, M; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Taniguchi, E; Tannenbaum, M J; Thomas, J; Thomas, J H; Thomas, T L; Tian, W; Tojo, J; Torii, H; Towell, R S; Tserruya, I; Tsuruoka, H; Tsvetkov, A A; Tuli, S K; Tydesjö, H; Tyurin, N; Ushiroda, T; van Hecke, H W; Velissaris, C; Velkovska, J; Velkovsky, M; Vinogradov, A A; Volkov, M A; Vorobyov, A; Vznuzdaev, E; Wang, H; Watanabe, Y; White, S N; Witzig, C; Wohn, F K; Woody, C L; Xie, W; Yagi, K; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, Z; Zhou, S

    2001-04-16

    We present results for the charged-particle multiplicity distribution at midrapidity in Au-Au collisions at square root of [s(NN)] = 130 GeV measured with the PHENIX detector at RHIC. For the 5% most central collisions we find dN(ch)/d eta(vertical line eta = 0) = 622+/-1(stat)+/-41(syst). The results, analyzed as a function of centrality, show a steady rise of the particle density per participating nucleon with centrality. PMID:11328008

  18. Au nanorod helical superstructures with designed chirality.

    PubMed

    Lan, Xiang; Lu, Xuxing; Shen, Chenqi; Ke, Yonggang; Ni, Weihai; Wang, Qiangbin

    2015-01-14

    A great challenge for nanotechnology is to controllably organize anisotropic nanomaterials into well-defined three-dimensional superstructures with customized properties. Here we successfully constructed anisotropic Au nanorod (AuNR) helical superstructures (helices) with tailored chirality in a programmable manner. By designing the 'X' pattern of the arrangement of DNA capturing strands (15nt) on both sides of a two-dimensional DNA origami template, AuNRs functionalized with the complementary DNA sequences were positioned on the origami and were assembled into AuNR helices with the origami intercalated between neighboring AuNRs. Left-handed (LH) and right-handed (RH) AuNR helices were conveniently accomplished by solely tuning the mirrored-symmetric 'X' patterns of capturing strands on the origami. The inter-rod distance was precisely defined as 14 nm and inter-rod angle as 45°, thus a full helix contains 9 AuNRs with its length up to about 220 nm. By changing the AuNR/origami molar ratio in the assembly system, the average number of AuNR in the helices was tuned from 2 to 4 and 9. Intense chiroptical activities arose from the longest AuNR helices with a maximum anisotropy factor of ∼0.02, which is highly comparable to the reported macroscopic AuNR assemblies. We expect that our strategy of origami templated assembly of anisotropic chiral superstructures would inspire the bottom-up fabrication of optically active nanostructures and shed light on a variety of applications, such as chiral fluids, chiral signal amplification, and fluorescence combined chiral spectroscopy. PMID:25516475

  19. Laser irradiation-induced Au-ZnO nanospheres with enhanced sensitivity and stability for ethanol sensing.

    PubMed

    Zhang, Hao; Wu, Shouliang; Liu, Jun; Cai, Yunyu; Liang, Changhao

    2016-08-10

    Incorporating noble metal nanoparticles on the surface or the inner side of semiconductors to form a hybrid nanostructure is an effective route for improving the gas sensing performance of the semiconductors. In this study, we present novel Au-decorated ZnO nanospheres (Au-ZnO NSs) obtained by the laser irradiation of liquids. Structural characterization indicated that the Au-ZnO NSs consisted of single crystalline ZnO NSs with a few Au nanoparticles decorated on their surfaces and abundant encapsulated Au nanoparticles with relatively small sizes. Laser irradiation-induced heating-melting-evaporating processes are responsible for the formation of unique Au-ZnO NSs. The gas sensing properties of the Au-ZnO NSs, as gas sensing materials, were investigated and compared with those of pure ZnO NSs. The former showed a lower working temperature, higher sensitivity, better selectivity, and good reproducibility. The response values of the Au-ZnO NS and pure ZnO NS sensors to ethanol of 100 ppm were 252 and 75 at a working temperature of 320 °C and 360 °C, respectively. Significant enhancements in gas sensing performance should be attributed to the electronic sensitization induced by the depleted layers between the encapsulated Au nanoparticles and ZnO and chemical sensitization originating from the catalytic effects of Au nanoparticles decorated on the surfaces that dissociated molecular oxygen. PMID:27465699

  20. Oxygen-assisted reduction of Au species on Au/SiO2 catalyst in room temperature CO oxidation

    SciTech Connect

    Wu, Zili; Zhou, Shenghu; Zhu, Haoguo; Dai, Sheng; Overbury, Steven {Steve} H

    2008-01-01

    An unexpected oxygen-assisted reduction of cationic Au species by CO was found on a Au/SiO2 catalyst at room temperature; CO oxidation activity increases simultaneously with the reduction of Au species, suggesting the key role of metallic Au played in CO oxidation on Au/SiO2.

  1. Electrochemical functionalization of Au by aminobenzene and 2-aminotoluene.

    PubMed

    Rösicke, F; Sun, G; Neubert, T; Janietz, S; Hinrichs, K; Rappich, J

    2016-03-01

    Au surfaces are functionalized by aminobenzene (AB) and 2-aminotoluene (AT) using the electrochemical reduction of diazotized 1,4-diaminobenzene and 2,5-diaminotoluene. The IR spectroscopic measurements reveal the successful modification of Au surfaces by AB and AT. Both types of layers show similar thicknesses as obtained by microgravimetric measurements via electrochemical quartz crystal microbalance (EQCM). However, the faradaic efficiency for the grafting of AT onto an EQCM-Au sensor was 6% compared to 41% for the grafting of AB. This behavior points to a steric hindrance during the binding of AT to the EQCM surface induced by the additional methyl group present in the toluene derivative. The AB and AT functionalized surfaces have been further modified by the amidation reaction of EDC/NHS activated 4-nitrobenzoic acid. This model system reveals that the amidation reaction is slightly hindered in case of the AT layer due to the presence of the methyl group close to the amino group. This behavior leads to a four times less amount of amide bonds at the AT compared to AB modified Au surfaces as obtained from IR spectroscopic measurements. PMID:26872104

  2. Electrochemical functionalization of Au by aminobenzene and 2-aminotoluene

    NASA Astrophysics Data System (ADS)

    Rösicke, F.; Sun, G.; Neubert, T.; Janietz, S.; Hinrichs, K.; Rappich, J.

    2016-03-01

    Au surfaces are functionalized by aminobenzene (AB) and 2-aminotoluene (AT) using the electrochemical reduction of diazotized 1,4-diaminobenzene and 2,5-diaminotoluene. The IR spectroscopic measurements reveal the successful modification of Au surfaces by AB and AT. Both types of layers show similar thicknesses as obtained by microgravimetric measurements via electrochemical quartz crystal microbalance (EQCM). However, the faradaic efficiency for the grafting of AT onto an EQCM-Au sensor was 6% compared to 41% for the grafting of AB. This behavior points to a steric hindrance during the binding of AT to the EQCM surface induced by the additional methyl group present in the toluene derivative. The AB and AT functionalized surfaces have been further modified by the amidation reaction of EDC/NHS activated 4-nitrobenzoic acid. This model system reveals that the amidation reaction is slightly hindered in case of the AT layer due to the presence of the methyl group close to the amino group. This behavior leads to a four times less amount of amide bonds at the AT compared to AB modified Au surfaces as obtained from IR spectroscopic measurements.

  3. Hollow alloy nanostructures templated by Au nanorods: synthesis, mechanistic insights, and electrocatalytic activity.

    PubMed

    Xue, Mengmeng; Tan, Yiwei

    2014-11-01

    A unique methodology having access to Au nanorods (AuNRs)-based hollow alloy nanostructures has been developed. The syntheses and characterization of the hollow Pt-Au nanoalloys with ellipsoidal and cylindrical shapes together with a rattle-type hollow Cu-Au nanoheterostructure are described. Unlike the conventional nanoscale Kirkendall process, the formation of these AuNRs-based hollow nanostructures occurs under extremely mild conditions, indicating a distinctive underlying mechanism. The key step for this present synthesis method is the incubation of AuNRs with CuCl2 at 60 °C in the presence of hexadecyltrimethylammonium bromide (CTAB) or hexadecyltrimethylammonium chloride (CTAC). The selective etching of the tips of AuNRs caused by Cu(2+) ions combined with the dissolved molecular oxygen promotes the generation of defects and vacancies, leading to a facile alloying reaction by the crystal fusion of AuNRs. Particularly, the results of the formation of the hollow nanoalloys in conjunction with various control experiments demonstrate that the halide ions that are specifically adsorbed on the AuNR surface afford sinks for vacancy accumulation and condensation during the unbalanced interdiffusion of alloying atoms, presumably because of the disproportion in the equilibrium concentration of vacancies. Thus, the void formation becomes kinetically favorable. The Pt-Au nanocages can provide modified surface electronic structures, resulting from their non-uniform crystalline structures and the surface segregation of Pt in the nanocages. These characteristics enable them to exhibit excellent electrocatalytic performance for the oxygen reduction reaction (ORR). PMID:25166262

  4. Measurement of Υ (1 S +2 S +3 S ) production in p +p and Au + Au collisions at √{sNN}=200 GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Bataineh, H.; Al-Ta'Ani, H.; Alexander, J.; Angerami, A.; Aoki, K.; Apadula, N.; Aphecetche, L.; Aramaki, Y.; Asai, J.; Asano, H.; Aschenauer, E. C.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Baldisseri, A.; Bannier, B.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Batsouli, S.; Baublis, V.; Baumann, C.; Baumgart, S.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bickley, A. A.; Bing, X.; Blau, D. S.; Boissevain, J. G.; Bok, J. S.; Borel, H.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Castera, P.; Chang, B. S.; Chang, W. C.; Charvet, J.-L.; Chen, C.-H.; Chernichenko, S.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Churyn, A.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Constantin, P.; Csanád, M.; Csörgő, T.; Dahms, T.; Dairaku, S.; Das, K.; Datta, A.; Daugherity, M. S.; David, G.; Denisov, A.; D'Enterria, D.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Ding, L.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Dubey, A. K.; Durham, J. M.; Durum, A.; Dutta, D.; Dzhordzhadze, V.; D'Orazio, L.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Eyser, K. O.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Gainey, K.; Gal, C.; Garishvili, A.; Garishvili, I.; Glenn, A.; Gong, H.; Gong, X.; Gonin, M.; Gosset, J.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Guo, L.; Gustafsson, H.-Å.; Hachiya, T.; Hadj Henni, A.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Han, R.; Hanks, J.; Hartouni, E. P.; Haruna, K.; Hashimoto, K.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Hollis, R. S.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hori, Y.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Iinuma, H.; Ikeda, Y.; Imai, K.; Imrek, J.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Ivanishchev, D.; Jacak, B. V.; Javani, M.; Jia, J.; Jiang, X.; Jin, J.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kaneti, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kikuchi, J.; Kim, B. I.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E.-J.; Kim, H. J.; Kim, K.-B.; Kim, S. H.; Kim, Y.-J.; Kim, Y. K.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Klatsky, J.; Klay, J.; Klein-Boesing, C.; Kleinjan, D.; Kline, P.; Kochenda, L.; Komatsu, Y.; Komkov, B.; Konno, M.; Koster, J.; Kotchetkov, D.; Kotov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Krizek, F.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Layton, D.; Lebedev, A.; Lee, B.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Lee, S. R.; Lee, T.; Leitch, M. J.; Leite, M. A. L.; Leitgab, M.; Lenzi, B.; Lewis, B.; Li, X.; Liebing, P.; Lim, S. H.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Malakhov, A.; Malik, M. D.; Manion, A.; Manko, V. I.; Mannel, E.; Mao, Y.; Mašek, L.; Masui, H.; Masumoto, S.; Matathias, F.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Means, N.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, D. K.; Mishra, M.; Mitchell, J. T.; Miyachi, Y.; Miyasaka, S.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Motschwiller, S.; Moukhanova, T. V.; Mukhopadhyay, D.; Murakami, T.; Murata, J.; Nagae, T.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Nederlof, A.; Newby, J.; Nguyen, M.; Nihashi, M.; Niida, T.; Nouicer, R.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, B. H.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Patel, L.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reygers, K.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; Riveli, N.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ružička, P.; Rykov, V. L.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakai, S.; Sakashita, K.; Samsonov, V.; Sano, M.; Sarsour, M.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Semenov, V.; Sen, A.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Soldatov, A.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Soumya, M.; Sourikova, I. V.; Staley, F.; Stankus, P. W.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Sugitate, T.; Suire, C.; Sukhanov, A.; Sun, J.; Sziklai, J.; Takagui, E. M.; Takahara, A.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tarján, P.; Tennant, E.; Themann, H.; Thomas, T. L.; Todoroki, T.; Togawa, M.; Toia, A.; Tomášek, L.; Tomášek, M.; Tomita, Y.; Torii, H.; Towell, R. S.; Tram, V.-N.; Tserruya, I.; Tsuchimoto, Y.; Tsuji, T.; Vale, C.; Valle, H.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vossen, A.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Wei, R.; Wessels, J.; Whitaker, S.; White, S. N.; Winter, D.; Wolin, S.; Woody, C. L.; Wysocki, M.; Xie, W.; Yamaguchi, Y. L.; Yamaura, K.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zaudtke, O.; Zelenski, A.; Zhang, C.; Zhou, S.; Zolin, L.; Phenix Collaboration

    2015-02-01

    Measurements of bottomonium production in heavy-ion and p +p collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The inclusive yield of the three Υ states, Υ (1 S +2 S +3 S ) , was measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au +Au and p +p collisions at √{sNN}=200 GeV. The Υ (1 S +2 S +3 S ) →e+e- differential cross section at midrapidity was found to be Beed σ /d y =108 ±38 (stat) ±15 (syst) ±11 (luminosity) pb in p +p collisions. The nuclear modification factor in the 30% most central Au +Au collisions indicates a suppression of the total Υ state yield relative to the extrapolation from p +p collision data. The suppression is consistent with measurements made by STAR at RHIC and at higher energies by the CMS experiment at the Large Hadron Collider.

  5. Energy and system size dependence of phi meson production in Cu+Cu and Au+Au collisions

    SciTech Connect

    STAR Coll

    2008-10-28

    We study the beam-energy and system-size dependence of {phi} meson production (using the hadronic decay mode {phi} {yields} K{sup +}K{sup -}) by comparing the new results from Cu + Cu collisions and previously reported Au + Au collisions at {radical}s{sub NN} = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented are from midrapidity (|y| < 0.5) for 0.4 < p{sub T} < 5 GeV/c. At a given beam energy, the transverse momentum distributions for {phi} mesons are observed to be similar in yield and shape for Cu + Cu and Au + Au colliding systems with similar average numbers of participating nucleons. The {phi} meson yields in nucleus-nucleus collisions, normalized by the average number of participating nucleons, are found to be enhanced relative to those from p + p collisions with a different trend compared to strange baryons. The enhancement for {phi} mesons is observed to be higher at {radical}s{sub NN} = 200 GeV compared to 62.4 GeV. These observations for the produced {phi}(s{bar s}) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems.

  6. Binding of Trivalent Arsenic onto the Tetrahedral Au20 and Au19Pt Clusters: Implications in Adsorption and Sensing.

    PubMed

    Cortés-Arriagada, Diego; Oyarzún, María Paz; Sanhueza, Luis; Toro-Labbé, Alejandro

    2015-07-01

    The interaction of arsenic(III) onto the tetrahedral Au20 cluster was studied computationally to get insights into the interaction of arsenic traces (presented in polluted waters) onto embedded electrodes with gold nanostructures. Pollutant interactions onto the vertex, edge, or inner gold atoms of Au20 were observed to have a covalent character by forming metal-arsenic or metal-oxygen bonding, with adsorption energies ranging from 0.5 to 0.8 eV, even with a stable physisorption; however, in aqueous media, the Au-vertex-pollutant interaction was found to be disadvantageous. The substituent effect of a platinum atom onto the Au20 cluster was evaluated to get insights into the changes in the adsorption and electronic properties of the adsorbent-adsorbate systems due to chemical doping. It was found that the dopant atom increases both the metal-pollutant adsorption energy and stability onto the support in a water media for all interaction modes; adsorption energies were found to be in a range of 0.6 to 1.8 eV. All interactions were determined to be accompanied by electron transfer as well as changes in the local reactivity that determine the amount of transferred charge and a decrease in the HOMO-LUMO energy gap with respect to the isolated substrate. PMID:26061641

  7. Phytosynthesis of Au, Ag and Au-Ag bimetallic nanoparticles using aqueous extract and dried leaf of Anacardium occidentale

    NASA Astrophysics Data System (ADS)

    Sheny, D. S.; Mathew, Joseph; Philip, Daizy

    2011-06-01

    Present study reports a green chemistry approach for the biosynthesis of Au, Ag, Au-Ag alloy and Au core-Ag shell nanoparticles using the aqueous extract and dried powder of Anacardium occidentale leaf. The effects of quantity of extract/powder, temperature and pH on the formation of nanoparticles are studied. The nanoparticles are characterized using UV-vis and FTIR spectroscopies, XRD, HRTEM and SAED analyses. XRD studies show that the particles are crystalline in the cubic phase. The formation of Au core-Ag shell nanoparticles is evidenced by the dark core and light shell images in TEM and is supported by the appearance of two SPR bands in the UV-vis spectrum. FTIR spectra of the leaf powder before and after the bioreduction of nanoparticles are used to identify possible functional groups responsible for the reduction and capping of nanoparticles. Water soluble biomolecules like polyols and proteins are expected to bring about the bio-reduction.

  8. Formation of Au-Pt alloy nanoparticles on a Si substrate by simple dip-coating at room temperature.

    PubMed

    Zhao, Liyan; Heinig, Nina; Leung, K T

    2013-01-22

    Spherical Au-Pt alloy nanoparticles of 10 nm average size have been prepared on a H-terminated Si(100) substrate by an extremely simple method of dip-coating. X-ray photoelectron spectroscopy and glancing-incidence X-ray diffraction confirm the formation of Au-Pt alloy. The Au(3+) ions are first reduced on the Si substrate upon dipping, and the freshly formed Au nuclei then work as a "catalyst" by promoting the reduction of PtCl(6)(2-) ions on the Au nuclei. The subsequent interdiffusion of Au and Pt atoms leads to the observed alloy formation. The present method provides an environment-friendly, low-cost route to preparing anode electrodes in fuel cells. PMID:23234580

  9. Interfacial oxygen under TiO{sub 2} supported Au clusters revealed by a genetic algorithm search

    SciTech Connect

    Vilhelmsen, Lasse B.; Hammer, Bjørk

    2013-11-28

    We present a density functional theory study of the oxidation of 1D periodic rods supported along the [001] direction on the rutile TiO{sub 2}(110) surface. The study shows evidence for an oxidation of the interface between the supported Au and the TiO{sub 2} crystal. The added O atoms adsorb at the 5f-Ti atoms in the through under the Au rod and are stabilized by charge transfer from the nearest Au atoms. Despite an extensive search, we find no low energy barrier pathways for CO oxidation involving CO adsorbed on Au and O at the perimeter of the Au/TiO{sub 2} interface. This is in part attributed the weak adsorption of CO on cationic Au at the perimeter.

  10. [(CF3)4Au2(C5H5N)2]--a new alkyl gold(II) derivative with a very short Au-Au bond.

    PubMed

    Zopes, David; Hegemann, Corinna; Tyrra, Wieland; Mathur, Sanjay

    2012-09-11

    A new gold(II) species [(CF(3))(4)Au(2)(C(5)H(5)N)(2)] with a very short unsupported Au-Au bond (250.62(9) pm) was generated by photo irradiation of a silver aurate, [Ag(Py)(2)][Au(CF(3))(2)], unambiguously characterized by (19)F and (109)Ag NMR studies. PMID:22836874

  11. Synthesis of Au/Graphene Oxide Composites for Selective and Sensitive Electrochemical Detection of Ascorbic Acid

    NASA Astrophysics Data System (ADS)

    Song, Jian; Xu, Lin; Xing, Ruiqing; Li, Qingling; Zhou, Chunyang; Liu, Dali; Song, Hongwei

    2014-12-01

    In this work, we present a novel ascorbic acid (AA) sensor applied to the detection of AA in human sera and pharmaceuticals. A series of Au nanoparticles (NPs) and graphene oxide sheets (Au NP/GO) composites were successfully synthesized by reduction of gold (III) using sodium citrate. Then the Au NP/GO composites were used to construct nonenzymatic electrodes in practical AA measurement. The electrode that has the best performance presents attractive analytical features, such as a low working potential of +0.15 V, a high sensitivity of 101.86 μA mM-1 cm-2 to AA, a low detection limit of 100 nM, good reproducibility and excellent selectivity. And more,it was also employed to accurately and practically detect AA in human serum and clinical vitamin C tablet with the existence of some food additive. The enhanced AA electrochemical properties of the Au NP/GO modified electrode in our work can be attributed to the improvement of electroactive surface area of Au NPs and the synergistic effect from the combination of Au NPs and GO sheets. This work shows that the Au NP/GO/GCEs hold the prospect for sensitive and selective determination of AA in practical clinical application.

  12. Synthesis of Au/Graphene Oxide Composites for Selective and Sensitive Electrochemical Detection of Ascorbic Acid

    PubMed Central

    Song, Jian; Xu, Lin; Xing, Ruiqing; Li, Qingling; Zhou, Chunyang; Liu, Dali; Song, Hongwei

    2014-01-01

    In this work, we present a novel ascorbic acid (AA) sensor applied to the detection of AA in human sera and pharmaceuticals. A series of Au nanoparticles (NPs) and graphene oxide sheets (Au NP/GO) composites were successfully synthesized by reduction of gold (III) using sodium citrate. Then the Au NP/GO composites were used to construct nonenzymatic electrodes in practical AA measurement. The electrode that has the best performance presents attractive analytical features, such as a low working potential of +0.15 V, a high sensitivity of 101.86 μA mM−1 cm−2 to AA, a low detection limit of 100 nM, good reproducibility and excellent selectivity. And more,it was also employed to accurately and practically detect AA in human serum and clinical vitamin C tablet with the existence of some food additive. The enhanced AA electrochemical properties of the Au NP/GO modified electrode in our work can be attributed to the improvement of electroactive surface area of Au NPs and the synergistic effect from the combination of Au NPs and GO sheets. This work shows that the Au NP/GO/GCEs hold the prospect for sensitive and selective determination of AA in practical clinical application. PMID:25515430

  13. The shape of Au8: gold leaf or gold nugget?

    NASA Astrophysics Data System (ADS)

    Serapian, Stefano A.; Bearpark, Michael J.; Bresme, Fernando

    2013-06-01

    The size at which nonplanar isomers of neutral, pristine gold nanoclusters become energetically favored over planar ones is still debated amongst theoreticians and experimentalists. Spectroscopy confirms planarity is preferred at sizes up to Au7, however, starting with Au8, the uncertainty remains for larger nanoclusters. Au8 computational studies have had different outcomes: the planar D4h ``cloverleaf'' isomer competes with the nonplanar Td, C2v and D2d ``nugget'' isomers for greatest energetic stability. We here examine the 2D vs. 3D preference in Au8 by presenting our own B2PLYP, MP2 and CCSD(T) calculations on these isomers: these methods afford a better treatment of long-range correlation, which is at the root of gold's characteristic aurophilicity. We then use findings from these high-accuracy computations to evaluate two less expensive DFT approaches, applicable to much larger nanoclusters: alongside the standard functional PBE, we consider M06-L (highly parametrized to incorporate long-range dispersive interactions). We find that increasing basis set size within the B2PLYP framework has a greater destabilizing effect on the nuggets than it has on the Au8 cloverleaf. Our CCSD(T) and B2PLYP predictions, replicated by DFT-PBE, all identify the cloverleaf as the most stable isomer; MP2 and DFT-M06-L show overestimation of aurophilicity, and favor, respectively, the nonplanar D2d and Td nuggets in its stead. We conclude that PBE, which more closely reproduces CCSD(T) findings, may be a better candidate density functional for the simulation of gold nanoclusters in this context.The size at which nonplanar isomers of neutral, pristine gold nanoclusters become energetically favored over planar ones is still debated amongst theoreticians and experimentalists. Spectroscopy confirms planarity is preferred at sizes up to Au7, however, starting with Au8, the uncertainty remains for larger nanoclusters. Au8 computational studies have had different outcomes: the planar D4

  14. Evaluation of diffuse neutron scattering at elevated temperatures and local decomposition in Ni-Au

    NASA Astrophysics Data System (ADS)

    Portmann, M. J.; Schönfeld, B.; Kostorz, G.; Altorfer, F.; Kohlbrecher, J.

    2003-07-01

    It is demonstrated that in the diffuse neutron scattering of alloys at elevated temperatures (i) the temperature dependence of the linear absorption coefficient is the reason for problems encountered hitherto in the evaluation of diffuse wide-angle scattering and (ii) small-angle neutron scattering has to be corrected for thermal diffuse scattering. These corrections are applied to published data of Ni-8.4 at. % Au and Ni-9.6 at. % Ti and are used to firmly establish that local decomposition is also present in Au-rich Ni-Au above the miscibility gap.

  15. Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au +Au Collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Z.; Sun, X. M.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Xu, H.; Xu, Z.; Xu, J.; Yang, S.; Yang, Y.; Yang, Y.; Yang, C.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, Y.; Zhang, J.; Zhang, J.; Zhang, S.; Zhang, S.; Zhang, Z.; Zhang, J. B.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2016-03-01

    We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au +Au collisions for energies ranging from √{sN N }=7.7 to 200 GeV. The third harmonic v32{2 }=⟨cos 3 (ϕ1-ϕ2)⟩ , where ϕ1-ϕ2 is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δ η =η1-η2 . Nonzero v32{2 } is directly related to the previously observed large-Δ η narrow-Δ ϕ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v32{2 } persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v32{2 } is consistent with zero. When scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v32{2 } for central collisions shows a minimum near √{sN N }=20 GeV .

  16. Measurement of Direct Photons in Ultra-Relativistic Au+Au Collisions

    NASA Astrophysics Data System (ADS)

    Gong, Haijiang

    Direct photons provide a tool to study the different stages of a heavy ion collision, especially the formation of the quark-gluon-plasma (QGP), without being influenced by the strong reaction and hadronization processes. The yield of direct photons can be determined from the inclusive photon yield and the photon yield from hadronic decays. At low pT, where a significant fraction of direct photon is expected to come from the thermalized medium of deconfined quarks and gluons and interacting hadrons, the measurement is very challenging. These so-called thermal photons carry information about the initial temperature of the medium. We present a new analysis technique that was developed to improve direct photon production measurement in the low and medium pT range. The technique was applied to the PHENIX Run4 Au+Au sqrt(sNN)=200GeV/c collisions dataset. It uses strict particle identification (PID) in the Electromagnetic Calorimeter (EMCal) and a charged particle veto to extract a clean photon signal. These photons are then tagged with EMCal photon candidates with loose PID cuts, which can be reconstructed with high efficiency, to determine the fraction of photons originating from neutral pion decays. Most systematic uncertainties and detector effects cancel in this method. The results are compared with recent PHENIX direct photon measurement through external conversion method and theoretical calculation predicting thermal photon production.

  17. Au-Ag-Cu nano-alloys: tailoring of permittivity

    NASA Astrophysics Data System (ADS)

    Hashimoto, Yoshikazu; Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius; Nishijima, Yoshiaki

    2016-04-01

    Precious metal alloys enables new possibilities to tailor materials for specific optical functions. Here we present a systematic study of the effects of a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different atomic mixing ratios. The permittivity was measured and analyzed numerically by applying the Drude model. X-ray diffraction (XRD) revealed the face centered cubic lattice of the alloys. Both, optical spectra and XRD results point towards an equivalent composition-dependent electron scattering behavior. Correlation between the fundamental structural parameters of alloys and the resulting optical properties is elucidated. Plasmonic properties of the Au-Ag-Cu alloy nanoparticles were investigated by numerical simulations. Guidelines for designing plasmonic response of nano- structures and their patterns are presented from the material science perspective.

  18. Au-Ag-Cu nano-alloys: tailoring of permittivity

    PubMed Central

    Hashimoto, Yoshikazu; Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius; Nishijima, Yoshiaki

    2016-01-01

    Precious metal alloys enables new possibilities to tailor materials for specific optical functions. Here we present a systematic study of the effects of a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different atomic mixing ratios. The permittivity was measured and analyzed numerically by applying the Drude model. X-ray diffraction (XRD) revealed the face centered cubic lattice of the alloys. Both, optical spectra and XRD results point towards an equivalent composition-dependent electron scattering behavior. Correlation between the fundamental structural parameters of alloys and the resulting optical properties is elucidated. Plasmonic properties of the Au-Ag-Cu alloy nanoparticles were investigated by numerical simulations. Guidelines for designing plasmonic response of nano- structures and their patterns are presented from the material science perspective. PMID:27118459

  19. Au-Ag-Cu nano-alloys: tailoring of permittivity.

    PubMed

    Hashimoto, Yoshikazu; Seniutinas, Gediminas; Balčytis, Armandas; Juodkazis, Saulius; Nishijima, Yoshiaki

    2016-01-01

    Precious metal alloys enables new possibilities to tailor materials for specific optical functions. Here we present a systematic study of the effects of a nanoscale alloying on the permittivity of Au-Ag-Cu metals at 38 different atomic mixing ratios. The permittivity was measured and analyzed numerically by applying the Drude model. X-ray diffraction (XRD) revealed the face centered cubic lattice of the alloys. Both, optical spectra and XRD results point towards an equivalent composition-dependent electron scattering behavior. Correlation between the fundamental structural parameters of alloys and the resulting optical properties is elucidated. Plasmonic properties of the Au-Ag-Cu alloy nanoparticles were investigated by numerical simulations. Guidelines for designing plasmonic response of nano- structures and their patterns are presented from the material science perspective. PMID:27118459

  20. Thermal and photoinduced reduction of ionic Au(III) to elemental Au nanoparticles by dissolved organic matter in water: possible source of naturally occurring Au nanoparticles.

    PubMed

    Yin, Yongguang; Yu, Sujuan; Liu, Jingfu; Jiang, Guibin

    2014-01-01

    Naturally occurring Au nanoparticles (AuNPs) have been widely observed in ore deposits, coal, soil, and environmental water. Identifying the source of these naturally occurring AuNPs could be helpful for not only the discovery of Au deposits through advanced exploration methods, but also the elucidation of the biogeochemical cycle and environmental toxicity of ionic Au and engineered AuNPs. Here, we investigated the effect of natural/simulated sunlight and heating on the reduction of ionic Au by ubiquitous dissolved organic matter (DOM) in river water. The reductive process probed by X-ray photoelectron spectroscopy revealed that phenolic, alcoholic, and aldehyde groups in DOM act as reductive sites. Long-time exposure with thermal and photoirradiation induced the further fusion and growth of AuNPs to branched Au nanostructure as precipitation. The formation processes and kinetics of AuNPs were further investigated using humic acid (HA) as the DOM model, with comprehensive characterizing methods. We have observed that HA can reduce ionic Au(III) complex (as chloride or hydroxyl complex) to elemental Au nanoparticles under sunlight or heating. In this process, nearly all of the Au(III) could be reduced to AuNPs, in which HA serves as not only the reductive agent, but also the coating agent to stabilize and disperse AuNPs. The size and stability of AuNPs were highly dependent on the concentration ratio of Au(III) to HA. These results imply that, besides biological processes, this thermal or photochemical reduction process is another possible source of naturally occurring AuNPs in natural environments, which possibly has critical impacts on the transport and transformation of Au and engineered AuNPs. PMID:24471802

  1. Self-assembly of thiolated cyanine aggregates on Au(111) and Au nanoparticle surfaces

    NASA Astrophysics Data System (ADS)

    Menéndez, Guillermo O.; Cortés, Emiliano; Grumelli, Doris; Méndez de Leo, Lucila P.; Williams, Federico J.; Tognalli, Nicolás G.; Fainstein, Alejandro; Vela, María Elena; Jares-Erijman, Elizabeth A.; Salvarezza, Roberto C.

    2012-01-01

    Heptamethinecyanine J-aggregates display sharp, intense fluorescence emission making them attractive candidates for developing a variety of chem-bio-sensing applications. They have been immobilized on planar thiol-covered Au surfaces and thiol-capped Au nanoparticles by weak molecular interactions. In this work the self-assembly of novel thiolated cyanine (CNN) on Au(111) and citrate-capped AuNPs from solutions containing monomers and J-aggregates has been studied by using STM, XPS, PM-IRRAS, electrochemical techniques and Raman spectroscopy. Data show that CNN species adsorb on the Au surfaces by forming thiolate-Au bonds. We found that the J-aggregates are preferentially adsorbed on the Au(111) surface directly from the solution while adsorbed CNN monomers cannot organize into aggregates on the substrate surface. These results indicate that the CNN-Au interaction is not able to disorganize the large J-aggregates stabilized by π-π stacking to optimize the S-Au binding site but it is strong enough to hinder the π-π stacking when CNNs are chemisorbed as monomers. The optical properties of the J-aggregates remain active after adsorption. The possibility of covalently bonding CNN J-aggregates to Au planar surfaces and Au nanoparticles controlling the J-aggregate/Au distance opens a new path regarding their improved stability and the wide range of biological applications of both CNN and AuNP biocompatible systems.Heptamethinecyanine J-aggregates display sharp, intense fluorescence emission making them attractive candidates for developing a variety of chem-bio-sensing applications. They have been immobilized on planar thiol-covered Au surfaces and thiol-capped Au nanoparticles by weak molecular interactions. In this work the self-assembly of novel thiolated cyanine (CNN) on Au(111) and citrate-capped AuNPs from solutions containing monomers and J-aggregates has been studied by using STM, XPS, PM-IRRAS, electrochemical techniques and Raman spectroscopy. Data show

  2. Photoionization of Au+, Au2+, and Au3+ ions and developments in the synthesis of the metallofullerene Au@C60

    NASA Astrophysics Data System (ADS)

    Kilcoyne, A. L. David; Muller, Alfred; Schippers, Stefan; Hellhund, Jonas; Borovik, Alexander; Mueller, Allison; Gross, Dylan; Johnson, Andrea; Macaluso, David; A. L. D. Kilcoyne Collaboration

    2015-05-01

    Absolute single photoionization of Au+, Au2+, and Au3+ ions was investigated via the merged-beams technique at AMO Beamline 10.0.1.2 of the Advanced Light Source at Lawrence Berkeley National Laboratory. The absolute single photoionization yield was measured as a function of photon energy for each species from the metastable state ionization threshold region to well above the ground state ionization potential. Additional high-resolution measurements were performed for Au+ and Au2+ ions in the region of the ground and metastable state ionization thresholds to better resolve the detailed resonant structure found therein. This structure was used, along with the reported excited state energy levels of Au+, to preliminarily identify previously unreported excitation levels in all three ions. In addition and as a component of the same program, photoionization studies of the endohedral metallofullerene Au@C60+were performed using endohedral fullerene samples synthesized on-site at Beamline 10.0.1.2 of the ALS.

  3. [Improved color purity of green OLED device based on Au thin film].

    PubMed

    Zhang, Yan-Fei; Zhao, Su-Ling; Xu, Zheng

    2014-04-01

    Au was used as anode in some kind of organic electroluminescent devices. Sometimes transparent Au electrodes are required, which means that the thickness of Au electrode should be as thin as possible. Therefore, two metals together forming an electrode become a choice. In the present paper, translucent Au/Al layer was inserted to anode side, and OLED device with the structure of ITO/Al (16 nm)/Au (10 nm)/TPD (30 nm)/AlQ (30 nm)/LiF (0.5 nm)/Al was prepared. There is a spectral narrowing phenomenon on the device ITO/TPD (30 nm)/AlQ (30 nm)/LiF (0. 5 nm)/Al, and through analysis and experiment it was found that this phenomenon comes from selective permeability to light of Au thin film rather than the microcavity effect. The device maintains wide viewing angle, without the angular dependence. And the color purity of device with Au thin film is improved. PMID:25007596

  4. Luminescent, bimetallic AuAg alloy quantum clusters in protein templates.

    PubMed

    Mohanty, Jyoti Sarita; Xavier, P Lourdu; Chaudhari, Kamalesh; Bootharaju, M S; Goswami, N; Pal, S K; Pradeep, T

    2012-07-21

    We report the synthesis of luminescent AuAg alloy quantum clusters (QCs) in bovine serum albumin (BSA), for the first time, with experimentally determined atomic composition. Mixing of the as-synthesized protein-protected Au and Ag clusters resulted in the formation of alloy AuAg clusters within the BSA. Mass spectrometric analysis of the product of a 1 : 1 molar ratio reaction mixture of Au(QC)@BSA and Ag(QC)@BSA suggested that the alloy clusters could be Au(38-x)Ag(x)@BSA. Further analyses by standard techniques revealed that the alloy cluster core of ∼1.2 nm diameter is composed of nearly zero valent Au and Ag atoms that exhibit distinctly different steady state and time resolved excited state luminescence profiles compared to the parent clusters. Tuning of the alloy composition was achieved by varying the molar ratio of the parent species in the reaction mixture and compositional changes were observed by mass spectrometry. In another approach, mixing of Au(3+) ions with the as-synthesized Ag(QC)@BSA also resulted in the formation of alloy clusters through galvanic exchange reactions. We believe that alloy clusters with the combined properties of the constituents in versatile protein templates would have potential applications in the future. The work presents interesting aspects of the reactivity of the protein-protected clusters. PMID:22684267

  5. Efficient plasmonic dye-sensitized solar cells with fluorescent Au-encapsulated C-dots.

    PubMed

    Narayanan, Remya; Deepa, Melepurath; Srivastava, Avanish Kumar; Shivaprasad, Sonnada Math

    2014-04-14

    A simple strategy to improve the efficiency of a ZnO-nanorod-based dye-sensitized solar cell (DSSC) by use of Au-encapsulated carbon dots (Au@C-dots) in the photoanode is presented. The localized surface plasmonic resonance of Au in the 500-550 nm range coupled with the ability of C-dots to undergo charge separation increase the energy-harvesting efficiency of the DSSC with ZnO/N719/Au@C-dots photoanodes. Charge transfer from N719 dye to Au@C-dots is confirmed by fluorescence and lifetime enhancements of Au@C-dots. Forster resonance energy transfer (FRET) from the gap states of ZnO nanorods to N719 dye is also ratified and the energy transfer rate is 4.4×10(8) s(-1) and the Forster radius is 1.89 nm. The overall power conversion efficiency of the plasmonic and FRET-enabled DSSC with ZnO/N719/Au@C-dots as the photoanode, I2/I(-) as the electrolyte and multiwalled carbon nanotubes as the counter electrode is 4.1%, greater by 29% compared to a traditional ZnO/N719 cell. PMID:24677662

  6. Formic Acid Decomposition on Au catalysts: DFT, Microkinetic Modeling, and Reaction Kinetics Experiments

    SciTech Connect

    Singh, Suyash; Li, Sha; Carrasquillo-Flores, Ronald; Alba-Rubio, Ana C.; Dumesic, James A.; Mavrikakis, Manos

    2014-04-01

    A combined theoretical and experimental approach is presented that uses a comprehensive mean-field microkinetic model, reaction kinetics experiments, and scanning transmission electron microscopy imaging to unravel the reaction mechanism and provide insights into the nature of active sites for formic acid (HCOOH) decomposition on Au/SiC catalysts. All input parameters for the microkinetic model are derived from periodic, self-consistent, generalized gradient approximation (GGA-PW91) density functional theory calculations on the Au(111), Au(100), and Au(211) surfaces and are subsequently adjusted to describe the experimental HCOOH decomposition rate and selectivity data. It is shown that the HCOOH decomposition follows the formate (HCOO) mediated path, with 100% selectivity toward the dehydrogenation products (CO21H2) under all reaction conditions. An analysis of the kinetic parameters suggests that an Au surface in which the coordination number of surface Au atoms is 4 may provide a better model for the active site of HCOOH decomposition on these specific supported Au catalysts.

  7. Forming ceria shell on Au-core by LSPR photothermal induced interface reaction

    NASA Astrophysics Data System (ADS)

    Qu, Y. H.; Liu, F.; Wei, Y.; Gu, C. L.; Zhang, L. H.; Liu, Y.

    2015-07-01

    A novel method for preparing core-shell structure of Au@ceria was presented, which is characterized with using photothermal effect from localized surface plasmon resonance (LSPR) to induce heat, and the heat can trigger the shell formation reactions confined on the surface of the Au nanoparticles (NPs). In short of the preparation procedure, aqueous sol of Au NPs, citric acid, ethylene glycol and cerous nitrate were irradiated with a Xe arc lamp, maintaining the temperature of the sol at 25 °C by cooling and stirring the sol. The Au NPs could generate heat from LSPR, and the heat induced polymerization reaction in the sol, resulting in cerium gel formation which enveloped each of the Au NPs, and the gel containing cerium formed only on the surface of the Au NPs. After calcination, Au@ceria was obtained. This method can be extended for preparing various core@shell nanocomposites in which metal cores possess LSPR effect and the shell formation can be induced by heat.

  8. Enzymatic deposition of Au nanoparticles on the designed electrode surface and its application in glucose detection.

    PubMed

    Zhang, Hongfang; Liu, Ruixiao; Sheng, Qinglin; Zheng, Jianbin

    2011-02-01

    This paper reported the enzymatic deposition of Au nanoparticles (AuNPs) on the designed 3-mercapto-propionic acid/glucose oxidase/chitosan (MPA/GOD/Chit) modified glassy carbon electrode and its application in glucose detection. Chit served as GOD immobilization matrix and interacted with MPA through electrostatic attraction. AuNPs, without nano-seeds presented on the electrode surface, was produced through the glucose oxidase catalyzed oxidation of glucose. The mechanism of production of AuNPs was confirmed to be that enzymatic reaction products H(2)O(2) in the solution reduce gold complex to AuNPs. The characterizations of the electrode modified after each assembly step was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy showed the average particle size of the AuNPs is 40nm with a narrow particle size distribution. The content of AuNPs on the electrode surfaces was measured by differential pulse stripping voltammetry. The electrochemical signals on voltammogram showed a linear increase with the glucose concentration in the range of 0.010-0.12mM with a detection limit of 4μM. This provided a method to the determination of glucose. PMID:21115279

  9. Au40: A large tetrahedral magic cluster

    NASA Astrophysics Data System (ADS)

    Jiang, De-En; Walter, Michael

    2011-11-01

    40 is a magic number for tetrahedral symmetry predicted in both nuclear physics and the electronic jellium model. We show that Au40 could be such a a magic cluster from density functional theory-based basin hopping for global minimization. The putative global minimum found for Au40 has a twisted pyramid structure, reminiscent of the famous tetrahedral Au20, and a sizable HOMO-LUMO gap of 0.69 eV, indicating its molecular nature. Analysis of the electronic states reveals that the gap is related to shell closings of the metallic electrons in a tetrahedrally distorted effective potential.

  10. Au40: A Large Tetrahedral Magic Cluster

    SciTech Connect

    Jiang, Deen; Walter, Michael

    2011-01-01

    40 is a magic number for tetrahedral symmetry predicted in both nuclear physics and the electronic jellium model. We show that Au{sub 40} could be such a magic cluster from density functional theory-based basin hopping for global minimization. The putative global minimum found for Au{sub 40} has a twisted pyramid structure, reminiscent of the famous tetrahedral Au{sub 20}, and a sizable HOMO-LUMO gap of 0.69 eV, indicating its molecular nature. Analysis of the electronic states reveals that the gap is related to shell closings of the metallic electrons in a tetrahedrally distorted effective potential.

  11. Non Photonic e-D0 correlations in p+p and Au+Au collisions at √SNN = 200 GeV

    NASA Astrophysics Data System (ADS)

    Geromitsos, Artemios

    2009-12-01

    The sum of charm and beauty in Au+Au collisions at 200 GeV measured through non-photonic electrons, show similar suppression at high pT as light hadrons, in contrast to expectations based on the dead cone effect. To understand this observation, it is important to separate the charm and beauty components. Non-photonic electron-D0 and electron-hadron azimuthal angular correlations are used to disentangle the contributions from charm and beauty decays. The beauty contribution in p+p. collisions at 200 GeV is found to be comparable to charm at pT˜5.5 GeV, indicating that beauty may contribute significantly to the non photonic electrons from heavy flavour decays in Au+Au data at high pT. Furthermore, we are employing microvertexing techniques, not used for the analysis of p+p collisions, in Au+Au collisions at 200 GeV. We present our analysis status of D0 meson reconstruction.

  12. Non Photonic e-D{sup 0} correlations in p+p and Au+Au collisions at {radical}(S{sub NN} = 200 GeV)

    SciTech Connect

    Geromitsos, Artemios

    2009-12-17

    The sum of charm and beauty in Au+Au collisions at 200 GeV measured through non-photonic electrons, show similar suppression at high p{sub T} as light hadrons, in contrast to expectations based on the dead cone effect. To understand this observation, it is important to separate the charm and beauty components. Non-photonic electron-D{sup 0} and electron-hadron azimuthal angular correlations are used to disentangle the contributions from charm and beauty decays. The beauty contribution in p+p. collisions at 200 GeV is found to be comparable to charm at p{sub T}{approx}5.5 GeV, indicating that beauty may contribute significantly to the non photonic electrons from heavy flavour decays in Au+Au data at high p{sub T}. Furthermore, we are employing microvertexing techniques, not used for the analysis of p+p collisions, in Au+Au collisions at 200 GeV. We present our analysis status of D{sub 0} meson reconstruction.

  13. Enhanced activity of Au-Fe/C anodic electrocatalyst for direct borohydride-hydrogen peroxide fuel cell

    NASA Astrophysics Data System (ADS)

    Yi, Lanhua; Wei, Wei; Zhao, Caixian; Tian, Li; Liu, Jing; Wang, Xianyou

    2015-07-01

    Carbon supported Au-Fe bimetallic nanocatalysts (Au-Fe/C) are facilely prepared via a modified NaBH4 reduction method in aqueous solution at room temperature, and used as the anode electrocatalyst of direct borohydride-hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the Au-Fe/C electrocatalysts are characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), rotating disc electrode (RDE) voltammetry, chronoamperometry (CA), chronopotentiometry (CP), and fuel cell test. The results show that Au-Fe/C catalysts display higher catalytic activity for the direct electrooxidation of BH4- than carbon supported pure Au nanocatalyst (Au/C), especially Au50Fe50/C catalyst presents the highest catalytic activity among all as-prepared catalysts. Besides, the single DBHFC with Au50Fe50/C anode and Au/C cathode obtains the maximum power density as high as 34.9 mW cm-2 at 25 °C.

  14. Macrophage Cell Membrane Camouflaged Au Nanoshells for in Vivo Prolonged Circulation Life and Enhanced Cancer Photothermal Therapy.

    PubMed

    Xuan, Mingjun; Shao, Jingxin; Dai, Luru; Li, Junbai; He, Qiang

    2016-04-20

    Macrophage cell membrane (MPCM)-camouflaged gold nanoshells (AuNS) that can serve as a new generation of photothermal conversion agents for in vivo photothermal cancer therapy are presented. They are constructed by the fusion of biocompatible AuNSs and MPCM vesicles. The resulting MPCM-coated AuNSs exhibited good colloidal stability and kept the original near-infrared (NIR) adsorption of AuNSs. Because AuNS carried high-density coverage of MPCMs, the totally functional portions of macrophage cells membrane were grafted onto the surface of AuNSs. This surface functionalization provided active targeting ability by recognizing tumor endothelium and thus improved tumoritropic accumulation compared to the red blood cell membrane-coating approach. These biomimetic nanoparticles significantly enhance in vivo blood circulation time and local accumulation at the tumor when administered systematically. Upon NIR laser irradiation, local heat generated by the MPCM-coated AuNS achieves high efficiency to suppress tumor growth and selectively ablate cancerous cells within the illuminated zone. Therefore, MPCM-coated AuNSs remained the natural properties of their source cells, which may improve the efficacy of photothermal therapy modulated by AuNSs and other noble-metal nanoparticles. PMID:27039688

  15. The AuScope geodetic VLBI array

    NASA Astrophysics Data System (ADS)

    Lovell, J. E. J.; McCallum, J. N.; Reid, P. B.; McCulloch, P. M.; Baynes, B. E.; Dickey, J. M.; Shabala, S. S.; Watson, C. S.; Titov, O.; Ruddick, R.; Twilley, R.; Reynolds, C.; Tingay, S. J.; Shield, P.; Adada, R.; Ellingsen, S. P.; Morgan, J. S.; Bignall, H. E.

    2013-06-01

    The AuScope geodetic Very Long Baseline Interferometry array consists of three new 12-m radio telescopes and a correlation facility in Australia. The telescopes at Hobart (Tasmania), Katherine (Northern Territory) and Yarragadee (Western Australia) are co-located with other space geodetic techniques including Global Navigation Satellite Systems (GNSS) and gravity infrastructure, and in the case of Yarragadee, satellite laser ranging (SLR) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) facilities. The correlation facility is based in Perth (Western Australia). This new facility will make significant contributions to improving the densification of the International Celestial Reference Frame in the Southern Hemisphere, and subsequently enhance the International Terrestrial Reference Frame through the ability to detect and mitigate systematic error. This, combined with the simultaneous densification of the GNSS network across Australia, will enable the improved measurement of intraplate deformation across the Australian tectonic plate. In this paper, we present a description of this new infrastructure and present some initial results, including telescope performance measurements and positions of the telescopes in the International Terrestrial Reference Frame. We show that this array is already capable of achieving centimetre precision over typical long-baselines and that network and reference source systematic effects must be further improved to reach the ambitious goals of VLBI2010.

  16. Au, Ge and AuGe Nanoparticles Fabricated by Laser Ablation

    SciTech Connect

    Musaev, O.R.; Sutter, E.; Wrobel, J.M.; Kruger, M.B.

    2012-02-01

    A eutectic AuGe target immersed in distilled water was ablated by pulsed ultraviolet laser light. The structure of the ablated material was investigated by high-resolution transmission electron microscopy (HRTEM). The images show formation of nanowire structures of AuGe up to 100 nm in length, with widths of 5-10 nm. These nanostructures have Ge content significantly lower than the target material. Electron diffraction demonstrates that they crystallize in the {alpha}-AuGe structure. For comparison, laser ablation of pure Au and pure Ge targets was also performed under the same conditions. HRTEM shows that Ge forms spherical nanoparticles with a characteristic size of {approx}30 nm. Au forms spherical nanoparticles with diameters of {approx}10 nm. Similar to AuGe, it also forms chainlike structures with substantially lower aspect ratio.

  17. Ir-induced activation of Au towards CO adsorption: Ir films deposited on Au{111}

    NASA Astrophysics Data System (ADS)

    Zhang, Tianfu; Driver, Stephen M.; Pratt, Stephanie J.; Jenkins, Stephen J.; King, David A.

    2016-06-01

    We have investigated the interaction of CO with Ir/Au{111} bimetallic surfaces, and the influence of morphology changes as Ir moves sub-surface into the Au bulk, using reflection-absorption infrared spectroscopy (RAIRS). The presence of Ir stabilises CO on exposed regions of the Au surface at temperatures up to around 200 K: we attribute this to low-coordinated Au sites, probably associated with lifting of the clean-surface 'herringbone' reconstruction by Ir deposition. The highest density of active Au sites is obtained after annealing the bimetallic surface to 500-600 K: we attribute this to morphology changes associated with the movement of Ir into bulk Au.

  18. Single cytidine units-templated syntheses of multi-colored water-soluble Au nanoclusters

    NASA Astrophysics Data System (ADS)

    Jiang, Hui; Zhang, Yuanyuan; Wang, Xuemei

    2014-08-01

    Ultra-small metallic nanoparticles, or so-called ``nanoclusters'' (NCs), have attracted considerable interest due to their unique optical properties that are different from both larger nanoparticles and single atoms. To prepare high-quality NCs, the stabilizing agent plays an essential role. In this work, we have revealed and validated that cytidine and its nucleotides (cytidine 5'-monophosphate or cytidine 5'-triphosphate) can act as efficient stabilizers for syntheses of multicolored Au NCs. Interestingly, Au NCs with blue, green and yellow fluorescence emissions are simultaneously obtained using various pH environments or reaction times. The transmission electron microscopy verifies that the size of Au NCs ranges from 1.5 to 3 nm. The X-ray photoelectron spectroscopy confirms that only Au (0) species are present in NCs. Generally, the facile preparation of multicolored Au NCs that are stabilized by cytidine units provides access to promising candidates for multiple biolabeling applications.Ultra-small metallic nanoparticles, or so-called ``nanoclusters'' (NCs), have attracted considerable interest due to their unique optical properties that are different from both larger nanoparticles and single atoms. To prepare high-quality NCs, the stabilizing agent plays an essential role. In this work, we have revealed and validated that cytidine and its nucleotides (cytidine 5'-monophosphate or cytidine 5'-triphosphate) can act as efficient stabilizers for syntheses of multicolored Au NCs. Interestingly, Au NCs with blue, green and yellow fluorescence emissions are simultaneously obtained using various pH environments or reaction times. The transmission electron microscopy verifies that the size of Au NCs ranges from 1.5 to 3 nm. The X-ray photoelectron spectroscopy confirms that only Au (0) species are present in NCs. Generally, the facile preparation of multicolored Au NCs that are stabilized by cytidine units provides access to promising candidates for multiple

  19. DNA bases assembled on the Au(110)/electrolyte interface: a combined experimental and theoretical study.

    PubMed

    Salvatore, Princia; Nazmutdinov, Renat R; Ulstrup, Jens; Zhang, Jingdong

    2015-02-19

    Among the low-index single-crystal gold surfaces, the Au(110) surface is the most active toward molecular adsorption and the one with fewest electrochemical adsorption data reported. Cyclic voltammetry (CV), electrochemically controlled scanning tunneling microscopy (EC-STM), and density functional theory (DFT) calculations have been employed in the present study to address the adsorption of the four nucleobases adenine (A), cytosine (C), guanine (G), and thymine (T), on the Au(110)-electrode surface. Au(110) undergoes reconstruction to the (1 × 3) surface in electrochemical environment, accompanied by a pair of strong voltammetry peaks in the double-layer region in acid solutions. Adsorption of the DNA bases gives featureless voltammograms with lower double-layer capacitance, suggesting that all the bases are chemisorbed on the Au(110) surface. Further investigation of the surface structures of the adlayers of the four DNA bases by EC-STM disclosed lifting of the Au(110) reconstruction, specific molecular packing in dense monolayers, and pH dependence of the A and G adsorption. DFT computations based on a cluster model for the Au(110) surface were performed to investigate the adsorption energy and geometry of the DNA bases in different adsorbate orientations. The optimized geometry is further used to compute models for STM images which are compared with the recorded STM images. This has provided insight into the physical nature of the adsorption. The specific orientations of A, C, G, and T on Au(110) and the nature of the physical adsorbate/surface interaction based on the combination of the experimental and theoretical studies are proposed, and differences from nucleobase adsorption on Au(111)- and Au(100)-electrode surfaces are discussed. PMID:25611676

  20. First enlargement within 1000 AU of a massive YSO

    NASA Astrophysics Data System (ADS)

    Sanna, A.

    2016-05-01

    We presented a comprehensive view, from scales of 0.1 pc down to 100 AU, of the gas dynamics driven by a massive young stellar object (YSO) in the star-forming region G023.01-00.41. Toward this region, we conducted both: 1) sub-arcsecond and high sensitivity Submillimeter Array (SMA) observations of different (e.g., CO, SiO, CH3CN, and CH3OH) molecular lines (Sanna et al. [2]), and 2) multi-epoch Very Long Baseline Interferometry (VLBI) observations of both H2O and CH3OH masers (Sanna et al. [3]). In particular, these VLBI observations allowed us to reconstruct, for the first time, both the 3D gas kinematics and magnetic field morphology in the vicinity (<1000 AU) of a massive YSO (Sanna et al. [1]).

  1. Counterion-Mediated Assembly of Spherical Nucleic Acid-Au Nanoparticle Conjugates (SNA-AuNPs)

    NASA Astrophysics Data System (ADS)

    Kewalramani, Sumit; Moreau, Liane; Guerrero-García, Guillermo; Mirkin, Chad; Olvera de La Cruz, Monica; Bedzyk, Michael; Afosr Muri Team

    2015-03-01

    Controlled crystallization of colloids from solution has been a goal of material scientists for decades. Recently, nucleic acid functionalized spherical Au nanoparticles (SNA-AuNPs) have been programmed to assemble in a wide variety of crystal structures. In this approach, the assembly is driven by Watson-Crick hybridization between DNAs coating the AuNPs. Here, we show that counterions can induce ordered assembly of SNA-AuNPs in bulk solutions, even in the absence of base pairing interactions. The electrostatics-driven assembly of spherical nucleic acid-Au nanoparticle conjugates (SNA-AuNPs) is probed as a function of counterion concentration and counterion valency [ +1 (Na+) or +2 (Ca2+) ] by in situ solution X-ray scattering. Assemblies of AuNPs capped with single-stranded (ss-) or double-stranded (ds-) DNA are examined. SAXS reveals disordered (gas-like) --> face-centered-cubic (FCC) --> glass-like phase transitions with increasing solution ionic strength. These studies demonstrate how non-base-pairing interactions can be tuned to create crystalline assemblies of SNA-AuNPs. The dependence of the inter-SNA-AuNP interactions on counterion valency and stiffness of the DNA corona will be discussed.

  2. Sclerometric study of galvanic AuNi and AuCo coatings

    NASA Astrophysics Data System (ADS)

    Shugurov, A. R.; Panin, A. V.; Shesterikov, E. V.

    2011-03-01

    Mechanisms of wear in galvanic AuNi and AuCo coatings have been studied using the methods of sclerometry and atomic force microscopy. It is demonstrated that the scratch test at a small load can be used for a comparative analysis of the resistance of metal coatings to abrasive wear. It is established that a developed surface relief related to the formation of grain agglomerates provides for a higher wear resistance of AuCo coatings as compared to that of smooth AuNi films, which is explained by dissipation of the elastic energy of the contact interaction of the sclerometric indenter with the sample surface.

  3. DFT study on cysteine adsorption mechanism on Au(111) and Au(110)

    SciTech Connect

    Buimaga-Iarinca, Luiza; Floare, Calin G.; Calborean, Adrian; Turcu, Ioan

    2013-11-13

    Periodic density functional theory calculations were used to investigate relevant aspects of adsorption mechanisms of cysteine dimers in protonated form on Au(111) and Au(110) surfaces. The projected densities of states are explicitly discussed for all main chemical groups of cysteine, i.e. the amino group (NH2), the thiol group (SH) and the carboxylic group (COOH) to identify differences in adsorption mechanism. Special emphasis is put on the analysis of changes in the electronic structure of molecules adsorbed on Au(111) and Au(110) surfaces as well as the accompanying charge transfer mechanisms at molecule-substrate interaction.

  4. Highly stable and sensitive glucose biosensor based on covalently assembled high density Au nanostructures.

    PubMed

    Si, Peng; Kannan, Palanisamy; Guo, Longhua; Son, Hungsun; Kim, Dong-Hwan

    2011-05-15

    We describe the development of a highly stable and sensitive glucose biosensor based on the nanohybrid materials derived from gold nanoparticles (AuNPs) and multi-walled carbon nanotubes (MWCNT). The biosensing platform was developed by using layer-by-layer (LBL) self-assembly of the nanohybrid materials and the enzyme glucose oxidase (GOx). A high density of AuNPs and MWCNT nanocomposite materials were constructed by alternate self assembly of thiol functionalized MWCNTs and AuNPs, followed by chemisoption of GOx. The surface morphology of multilayered AuNPs/MWCNT structure was characterized by field emission-scanning electron microscope (FE-SEM), and the surface coverage of AuNPs was investigated by cyclic voltammetry (CV), showing that 5 layers of assembly achieves the maximum particle density on electrode. The immobilization of GOx was monitored by electrochemical impedance spectroscopy (EIS). CV and amperometry methods were used to study the electrochemical oxidation of glucose at physiological pH 7.4. The Au electrode modified with five layers of AuNPs/MWCNT composites and GOx exhibited an excellent electrocatalytic activity towards oxidation of glucose, which presents a wide liner range from 20 μM to 10 mM, with a sensitivity of 19.27 μA mM(-1) cm(-2). The detection limit of present modified electrode was found to be 2.3 μM (S/N=3). In addition, the resulting biosensor showed a faster amperometric current response (within 3 s) and low apparent Michaelis-Menten constant (K(m)(app)). Our present study shows that the high density of AuNPs decorated MWCNT is a promising nanohybrid material for the construction of enzyme based electrochemical biosensors. PMID:21454070

  5. Au and Pd nanoparticles supported on CeO2, TiO2, and Mn2O3 oxides

    NASA Astrophysics Data System (ADS)

    Nascente, P. A. P.; Maluf, S. S.; Afonso, C. R. M.; Landers, R.; Pinheiro, A. N.; Leite, E. R.

    2014-10-01

    Gold and palladium nanoparticles were incorporated on CeO2, TiO2, and Mn2O3 supports prepared by a sol-gel method. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high resolution TEM (HRTEM), scanning TEM (STEM) in high angle annular dark field mode (HAADF), and energy filtered TEM (EFTEM) using electron energy loss spectroscopy (EELS). The XRD diffractograms presented sharp and intense peaks indicating that the samples are highly crystalline, but it did not detected any peak corresponding to Au or Pd phases. This indicates that the Au and Pd NPs were incorporated into the structures of the oxides. It was not possible to obtain an Au 4f spectrum for Au/Mn2O3 due to an overlap with the Mn 3p spectrum. The XPS Au 4f spectra for Au/CeO2 and Au/TiO2 present negative chemical shifts that could be attributed to particle-size-related properties. The XPS Pd 3d spectra indicate that for both CeO2 and TiO2 substrates, the Pd NPs were in the metallic state, while for the Mn2O3 substrate, the Pd NPs were oxidized. The HRTEM results show the formation of nanocrystalline oxides having particles sizes between 50 and 200 nm. TEM micrographs show that the addition of Au caused the formation of Au clusters in between the CeO2 NPS, formation of Au NPs for the TiO2 support, and homogeneous distribution of Au clusters for the Mn2O3 support. The addition of Pd yielded a homogeneous dispersion throughout the CeO2 and TiO2, but caused the formation of Pd clusters for the Mn2O3 support.

  6. Self-assembly of alkanols on Au(111) surfaces.

    PubMed

    Zhang, Hai-Ming; Yan, Jia-Wei; Xie, Zhao-Xiong; Mao, Bing-Wei; Xu, Xin

    2006-05-15

    Self-assembled monolayers (SAMs) of alkanols (1-C(N)H(2N+1)OH) with varying carbon-chain lengths (N = 10-30) have been systematically studied by means of scanning tunneling microscopy (STM) at the interfaces between alkanol solutions (or liquids) and Au(111) surfaces. The carbon skeletons were found to lie flat on the surfaces. This orientation is consistent with SAMs of alkanols on highly oriented pyrolytic graphite (HOPG) and MoS2 surfaces, and also with alkanes on reconstructed Au(111) surfaces. This result differs from a prior report, which claimed that 1-decanol molecules (N = 10) stood on their ends with the OH polar groups facing the gold substrate. Compared to alkanes, the replacement of one terminal CH3 group with an OH group introduces new bonding features for alkanols owing to the feasibility of forming hydrogen bonds. While SAMs of long-chain alkanols (N > 18) resemble those of alkanes, in which the aliphatic chains make a greater contribution, hydrogen bonding plays a more important role in the formation of SAMs of short-chain alkanols. Thus, in addition to the titled lamellar structure, a herringbone-like structure, seldom seen in SAMs of alkanes, is dominant in alkanol SAMs for values of N < 18. The odd-even effect present in alkane SAMs is also present in alkanol SAMs. Thus, the odd N alkanols (alkanols with an odd number of carbon atoms) adopt perpendicular lamellar structures owing to the favorable interactions of the CH3 terminal groups, similar to the result observed for odd alkanes. In contrast to alkanes on Au(111) surfaces, for which no SAMs on an unreconstructed gold substrate were observed, alkanols are capable of forming SAMs on either the reconstructed or the unreconstructed gold surfaces. Structural models for the packing of alkanol molecules on Au(111) surfaces have been proposed, which successfully explain these experimental observations. PMID:16534826

  7. Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR

    SciTech Connect

    STAR Coll

    2009-04-11

    Identified charged particle spectra of {pi}{sup {+-}}, K{sup {+-}}, p and {bar p} at mid-rapidity (|y| < 0.1) measured by the dE/dx method in the STAR-TPC are reported for pp and d + Au collisions at {radical}s{sub NN} = 200 GeV and for Au + Au collisions at 62.4 GeV, 130 GeV, and 200 GeV. Average transverse momenta, total particle production, particle yield ratios, strangeness and baryon production rates are investigated as a function of the collision system and centrality. The transverse momentum spectra are found to be flatter for heavy particles than for light particles in all collision systems; the effect is more prominent for more central collisions. The extracted average transverse momentum of each particle species follows a trend determined by the total charged particle multiplicity density. The Bjorken energy density estimate is at least several GeV/fm{sub 3} for a formation time less than 1 fm/c. A significantly larger net-baryon density and a stronger increase of the net-baryon density with centrality are found in Au + Au collisions at 62.4 GeV than at the two higher energies. Antibaryon production relative to total particle multiplicity is found to be constant over centrality, but increases with the collision energy. Strangeness production relative to total particle multiplicity is similar at the three measured RHIC energies. Relative strangeness production increases quickly with centrality in peripheral Au + Au collisions, to a value about 50% above the pp value, and remains rather constant in more central collisions. Bulk freeze-out properties are extracted from thermal equilibrium model and hydrodynamics-motivated blast-wave model fits to the data. Resonance decays are found to have little effect on the extracted kinetic freeze-out parameters due to the transverse momentum range of our measurements. The extracted chemical freeze-out temperature is constant, independent of collision system or centrality; its value is close to the predicted phase

  8. Systematic measurements of identified particle spectra in pp, d+Au, and Au+Au collisions at the star detector.

    SciTech Connect

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Krueger, K.; Spinka, H. M.; Underwood, D. G.; High Energy Physics; Univ. of Illinois; Panjab Univ.; Variable Energy Cyclotron Centre; Kent State Univ.; Particle Physic Lab.; STAR Collaboration

    2009-01-01

    Identified charged-particle spectra of {pi}{sup {+-}}, K{sup {+-}}, p, and {bar p} at midrapidity (|y|<0.1) measured by the dE/dx method in the STAR (solenoidal tracker at the BNL Relativistic Heavy Ion Collider) time projection chamber are reported for pp and d+Au collisions at {radical}s{sub NN} = 200 GeV and for Au+Au collisions at 62.4, 130, and 200 GeV. Average transverse momenta, total particle production, particle yield ratios, strangeness, and baryon production rates are investigated as a function of the collision system and centrality. The transverse momentum spectra are found to be flatter for heavy particles than for light particles in all collision systems; the effect is more prominent for more central collisions. The extracted average transverse momentum of each particle species follows a trend determined by the total charged-particle multiplicity density. The Bjorken energy density estimate is at least several GeV/fm{sup 3} for a formation time less than 1 fm/c. A significantly larger net-baryon density and a stronger increase of the net-baryon density with centrality are found in Au+Au collisions at 62.4 GeV than at the two higher energies. Antibaryon production relative to total particle multiplicity is found to be constant over centrality, but increases with the collision energy. Strangeness production relative to total particle multiplicity is similar at the three measured RHIC energies. Relative strangeness production increases quickly with centrality in peripheral Au+Au collisions, to a value about 50% above the pp value, and remains rather constant in more central collisions. Bulk freeze-out properties are extracted from thermal equilibrium model and hydrodynamics-motivated blast-wave model fits to the data. Resonance decays are found to have little effect on the extracted kinetic freeze-out parameters because of the transverse momentum range of our measurements. The extracted chemical freeze-out temperature is constant, independent of

  9. Systematic measurements of identified particle spectra in pp, d+Au, and Au+Au collisions at the STAR detector

    NASA Astrophysics Data System (ADS)

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Baumgart, S.; Beavis, D. R.; Bellwied, R.; Benedosso, F.; Betts, R. R.; Bhardwaj, S.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Biritz, B.; Bland, L. C.; Bombara, M.; Bonner, B. E.; Botje, M.; Bouchet, J.; Braidot, E.; Brandin, A. V.; Bruna, E.; Bueltmann, S.; Burton, T. P.; Bystersky, M.; Cai, X. Z.; Caines, H.; Sánchez, M. Calderón De La Barca; Callner, J.; Catu, O.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K. E.; Christie, W.; Chung, S. U.; Clarke, R. F.; Codrington, M. J. M.; Coffin, J. P.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; Silva, C. De; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; de Souza, R. Derradi; Didenko, L.; Djawotho, P.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, F.; Dunlop, J. C.; Mazumdar, M. R. Dutta; Edwards, W. R.; Efimov, L. G.; Elhalhuli, E.; Elnimr, M.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gaillard, L.; Gangadharan, D. R.; Ganti, M. S.; Garcia-Solis, E.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S. M.; Guimaraes, K. S. F. F.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; He, W.; Heinz, M.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D. J.; Hollis, R. S.; Huang, H. Z.; Humanic, T. J.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jin, F.; Jones, P. G.; Joseph, J.; Judd, E. G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V. Yu.; Kiryluk, J.; Kisiel, A.; Klein, S. R.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Kopytine, M.; Kotchenda, L.; Kouchpil, V.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Krus, M.; Kuhn, C.; Kumar, L.; Kurnadi, P.; Lamont, M. A. C.; Landgraf, J. M.; Lapointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Levine, M. J.; Li, C.; Li, Y.; Lin, G.; Lin, X.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ludlam, T.; Lynn, D.; Ma, G. L.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mall, O. I.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Matis, H. S.; Matulenko, Yu. A.; McShane, T. S.; Meschanin, A.; Millane, J.; Miller, M. L.; Minaev, N. G.; Mioduszewski, S.; Mischke, A.; Mitchell, J.; Mohanty, B.; Molnar, L.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Nepali, C.; Netrakanti, P. K.; Ng, M. J.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okada, H.; Okorokov, V.; Olson, D.; Pachr, M.; Page, B. S.; Pal, S. K.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Planinic, M.; Pluta, J.; Poljak, N.; Poskanzer, A. M.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Putschke, J.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Reed, R.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Rykov, V.; Sahoo, R.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sarsour, M.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S. S.; Shi, X.-H.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Skoby, M. J.; Smirnov, N.; Snellings, R.; Sorensen, P.; Sowinski, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, T. D. S.; Staszak, D.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Symons, T. J. M.; de Toledo, A. Szanto; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Timoshenko, S.; Tlusty, D.; Tokarev, M.; Tram, V. N.; Trattner, A. L.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; Buren, G. Van; van Leeuwen, M.; Molen, A. M. Vander; Vanfossen, J. A., Jr.; Varma, R.; Vasconcelos, G. M. S.; Vasilevski, I. M.; Vasiliev, A. N.; Videbaek, F.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Waggoner, W. T.; Wang, F.; Wang, G.; Wang, J. S.; Wang, Q.; Wang, X.; Wang, X. L.; Wang, Y.; Webb, J. C.; Westfall, G. D.; Whitten, C., Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yepes, P.; Yoo, I.-K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, H.; Zhang, S.; Zhang, W. M.; Zhang, Y.; Zhang, Z. P.; Zhao, Y.; Zhong, C.; Zhou, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zuo, J. X.

    2009-03-01

    Identified charged-particle spectra of π±, K±, p, and pmacr at midrapidity (|y|<0.1) measured by the dE/dx method in the STAR (solenoidal tracker at the BNL Relativistic Heavy Ion Collider) time projection chamber are reported for pp and d+Au collisions at sNN=200 GeV and for Au+Au collisions at 62.4, 130, and 200 GeV. Average transverse momenta, total particle production, particle yield ratios, strangeness, and baryon production rates are investigated as a function of the collision system and centrality. The transverse momentum spectra are found to be flatter for heavy particles than for light particles in all collision systems; the effect is more prominent for more central collisions. The extracted average transverse momentum of each particle species follows a trend determined by the total charged-particle multiplicity density. The Bjorken energy density estimate is at least several GeV/fm3 for a formation time less than 1 fm/c. A significantly larger net-baryon density and a stronger increase of the net-baryon density with centrality are found in Au+Au collisions at 62.4 GeV than at the two higher energies. Antibaryon production relative to total particle multiplicity is found to be constant over centrality, but increases with the collision energy. Strangeness production relative to total particle multiplicity is similar at the three measured RHIC energies. Relative strangeness production increases quickly with centrality in peripheral Au+Au collisions, to a value about 50% above the pp value, and remains rather constant in more central collisions. Bulk freeze-out properties are extracted from thermal equilibrium model and hydrodynamics-motivated blast-wave model fits to the data. Resonance decays are found to have little effect on the extracted kinetic freeze-out parameters because of the transverse momentum range of our measurements. The extracted chemical freeze-out temperature is constant, independent of collision system or centrality; its value is close

  10. Characterization of single 1.8-nm Au nanoparticle attachments on AFM tips for single sub-4-nm object pickup

    PubMed Central

    2013-01-01

    This paper presents a novel method for the attachment of a 1.8-nm Au nanoparticle (Au-NP) to the tip of an atomic force microscopy (AFM) probe through the application of a current-limited bias voltage. The resulting probe is capable of picking up individual objects at the sub-4-nm scale. We also discuss the mechanisms involved in the attachment of the Au-NP to the very apex of an AFM probe tip. The Au-NP-modified AFM tips were used to pick up individual 4-nm quantum dots (QDs) using a chemically functionalized method. Single QD blinking was reduced considerably on the Au-NP-modified AFM tip. The resulting AFM tips present an excellent platform for the manipulation of single protein molecules in the study of single protein-protein interactions. PMID:24237663

  11. Structural, electrochemical and spectroelectrochemical study on the geometric and electronic structures of [(corrolato)Au(III)](n) (n = 0, +1, -1) complexes.

    PubMed

    Sinha, Woormileela; Sommer, Michael G; van der Meer, Margarethe; Plebst, Sebastian; Sarkar, Biprajit; Kar, Sanjib

    2016-02-21

    Synthesis of two new Au(III) corrole complexes with unsymmetrically substituted corrole ligands is presented here. The newly synthesized Au-compounds have been characterized by various spectroscopic techniques. The structural characterization of a representative Au(III) corrole has also been possible. Electrochemical, UV-vis-NIR/EPR spectroelectrochemical and DFT studies have been used to decipher the electronic structures of various electro-generated species. These are the first UV-vis-NIR/EPR spectroelectrochemical investigations on Au(III) corroles. Assignment of redox states of electro-generated Au(III) corroles is supported by DFT analysis. In contrast to the metal centered reduction reported in Au(III) porphyrins, one electron reduction in Au(III) corroles has been assigned to corrole centered on the basis of experimental and theoretical studies. Thus, the Au(III) corroles (not the analogous Au(III) porphyrin derivatives!) bear a truly redox inactive Au(III) center. Additionally, these Au-corrole complexes display NIR electrochromism, the origin of which is all on corrole-centered processes. PMID:26750146

  12. First-principles study of structural, elastic and thermodynamic properties of AuIn2

    NASA Astrophysics Data System (ADS)

    Wu, Hai Ying; Chen, Ya Hong; Deng, Chen Rong; Yin, Peng Fei; Cao, Hong

    2015-12-01

    The structural, elastic and thermodynamic properties of AuIn2 in the CaF2 structure under pressure have been investigated using ab initio plane wave pseudopotential method within the generalized gradient approximation. The calculated structural parameters and equation of state are in excellent agreement with the available experimental and theoretical results. The elastic constants of AuIn2 at ambient condition are calculated, and the bulk modulus obtained from these calculated elastic constants agrees well with the experimental data. The pressure dependence of the elastic constants, bulk modulus, shear modulus and Young’s modulus has also been investigated. The Debye temperature presents a slight increase with pressure. AuIn2 exhibits ductibility and low hardness characteristics, the ductibility increases while the hardness decreases with the increasing of pressure. The pressure effect on the heat capacity and thermal expansion coefficient for AuIn2 is much larger.

  13. A RESOLVED MILLIMETER EMISSION BELT IN THE AU Mic DEBRIS DISK

    SciTech Connect

    Wilner, David J.; Andrews, Sean M.; MacGregor, Meredith A.; Meredith Hughes, A.

    2012-04-20

    We present imaging observations at 1.3 mm of the debris disk surrounding the nearby M-type flare star AU Mic with beam size 3'' (30 AU) from the Submillimeter Array. These data reveal a belt of thermal dust emission surrounding the star with the same edge-on geometry as the more extended scattered light disk detected at optical wavelengths. Simple modeling indicates a central radius of {approx}35 AU for the emission belt. This location is consistent with the reservoir of planetesimals previously invoked to explain the shape of the scattered light surface brightness profile through size-dependent dust dynamics. The identification of this belt further strengthens the kinship between the debris disks around AU Mic and its more massive sister star {beta} Pic, members of the same {approx}10 Myr old moving group.

  14. Length distributions of Au-catalyzed and In-catalyzed InAs nanowires

    NASA Astrophysics Data System (ADS)

    Dubrovskii, V. G.; Sibirev, N. V.; Berdnikov, Y.; Gomes, U. P.; Ercolani, D.; Zannier, V.; Sorba, L.

    2016-09-01

    We present experimental data on the length distributions of InAs nanowires grown by chemical beam epitaxy with Au catalyst nanoparticles obtained by thermal dewetting of Au film, Au colloidal nanoparticles and In droplets. Poissonian length distributions are observed in the first case. Au colloidal nanoparticles produce broader and asymmetric length distributions of InAs nanowires. However, the distributions can be strongly narrowed by removing the high temperature annealing step. The length distributions for the In-catalyzed growth are instead very broad. We develop a generic model that is capable of describing the observed behaviors by accounting for both the incubation time for nanowire growth and secondary nucleation of In droplets. These results allow us to formulate some general recipes for obtaining more uniform length distributions of III-V nanowires.

  15. Extremely high efficient nanoreactor with Au@ZnO catalyst for photocatalysis.

    PubMed

    Su, Chung-Yi; Yang, Tung-Han; Gurylev, Vitaly; Huang, Sheng-Hsin; Wu, Jenn-Ming; Perng, Tsong-Pyng

    2015-10-01

    We fabricated a photocatalytic Au@ZnO@PC (polycarbonate) nanoreactor composed of monolayered Au nanoparticles chemisorbed on conformal ZnO nanochannel arrays within the PC membrane. A commercial PC membrane was used as the template for deposition of a ZnO shell into the pores by atomic layer deposition (ALD). Thioctic acid (TA) with sufficient steric stabilization was used as a molecular linker for functionalization of Au nanoparticles in a diameter of 10 nm. High coverage of Au nanoparticles anchored on the inner wall of ZnO nanochannels greatly improved the photocatalytic activity for degradation of Rhodamine B. The membrane nanoreactor achieved 63% degradation of Rhodamine B within only 26.88 ms of effective reaction time owing to its superior mass transfer efficiency based on Damköhler number analysis. Mass transfer limitation can be eliminated in the present study due to extremely large surface-to-volume ratio of the membrane nanoreactor. PMID:26358837

  16. Extremely high efficient nanoreactor with Au@ZnO catalyst for photocatalysis

    NASA Astrophysics Data System (ADS)

    Su, Chung-Yi; Yang, Tung-Han; Gurylev, Vitaly; Huang, Sheng-Hsin; Wu, Jenn-Ming; Perng, Tsong-Pyng

    2015-10-01

    We fabricated a photocatalytic Au@ZnO@PC (polycarbonate) nanoreactor composed of monolayered Au nanoparticles chemisorbed on conformal ZnO nanochannel arrays within the PC membrane. A commercial PC membrane was used as the template for deposition of a ZnO shell into the pores by atomic layer deposition (ALD). Thioctic acid (TA) with sufficient steric stabilization was used as a molecular linker for functionalization of Au nanoparticles in a diameter of 10 nm. High coverage of Au nanoparticles anchored on the inner wall of ZnO nanochannels greatly improved the photocatalytic activity for degradation of Rhodamine B. The membrane nanoreactor achieved 63% degradation of Rhodamine B within only 26.88 ms of effective reaction time owing to its superior mass transfer efficiency based on Damköhler number analysis. Mass transfer limitation can be eliminated in the present study due to extremely large surface-to-volume ratio of the membrane nanoreactor.

  17. Length distributions of Au-catalyzed and In-catalyzed InAs nanowires.

    PubMed

    Dubrovskii, V G; Sibirev, N V; Berdnikov, Y; Gomes, U P; Ercolani, D; Zannier, V; Sorba, L

    2016-09-16

    We present experimental data on the length distributions of InAs nanowires grown by chemical beam epitaxy with Au catalyst nanoparticles obtained by thermal dewetting of Au film, Au colloidal nanoparticles and In droplets. Poissonian length distributions are observed in the first case. Au colloidal nanoparticles produce broader and asymmetric length distributions of InAs nanowires. However, the distributions can be strongly narrowed by removing the high temperature annealing step. The length distributions for the In-catalyzed growth are instead very broad. We develop a generic model that is capable of describing the observed behaviors by accounting for both the incubation time for nanowire growth and secondary nucleation of In droplets. These results allow us to formulate some general recipes for obtaining more uniform length distributions of III-V nanowires. PMID:27501469

  18. Scaling Properties of Hyperon Production in Au + Au Collisions at sqrt sNN = 200 GeV

    SciTech Connect

    Adams, J.

    2006-06-08

    We present the scaling properties of Lambda, Xi, and their anti-particles produced at mid-rapidity in Au+Au collisions at RHIC at psNN = 200 GeV. The yield of multi-strange baryons per participant nucleon increases from peripheral to central collisions more rapidly than the Lambda yield, which appears to correspond to an increasing strange quark density of matter produced. The value of the strange phase space occupancy factor gamma s, obtained from a thermal model fit to the data, approaches unity for the most central collisions. We also show that the nuclear modification factors, RCP, of Lambda and Xi are consistent with each other and with that of protons in the transverse momentum range2.0< pT< 5.0 GeV/c. This scaling behaviour is consistent with a scenario of hadron formation from constituent quark degrees of freedom through quark recombination or coalescence.

  19. Dielectron Azimuthal Anisotropy at mid-rapidity in Au+Au collisions at root s=200GeV

    DOE PAGESBeta

    Adamczyk, L.

    2014-12-11

    We report on the first measurement of the azimuthal anisotropy (v₂) of dielectrons (e⁺e⁻ pairs) at mid-rapidity from √(sNN)=200 GeV Au + Au collisions with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), presented as a function of transverse momentum (pT) for different invariant-mass regions. In the mass region Mee<1.1 GeV/c² the dielectron v₂ measurements are found to be consistent with expectations from π⁰,η,ω, and Φ decay contributions. In the mass region 1.1ee<2.9GeV/c², the measured dielectron v₂ is consistent, within experimental uncertainties, with that from the cc¯ contributions.

  20. Enhanced magneto-plasmonic effect in Au/Co/Au multilayers caused by exciton-plasmon strong coupling

    NASA Astrophysics Data System (ADS)

    Hamidi, S. M.; Ghaebi, O.

    2016-09-01

    In this paper, we have investigated magneto optical Kerr rotation using the strong coupling of exciton-plasmon. For this purpose, we have demonstrated strong coupling phenomenon using reflectometry measurements. These measurements revealed the formation of two split polaritonic extrema in reflectometry as a function of wavelength. Then we have shown exciton-plasmon coupling in dispersion diagram which presented an anti-crossing between the polaritonic branches. To assure the readers of strong coupling, we have shown an enhanced magneto-optical Kerr rotation by comparing the reflectometry results of strong coupling of surface Plasmon polariton of Au/Co/Au multilayer and R6G excitons with surface Plasmon polariton magneto-optical kerr effect experimental setup.

  1. Beam-energy dependence of charge separation along the magnetic field in Au+Au collisions at RHIC.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Voloshin, S A; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-08-01

    Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au+Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies. PMID:25126911

  2. Dielectron Azimuthal Anisotropy at mid-rapidity in Au+Au collisions at root s=200GeV

    SciTech Connect

    Adamczyk, L.

    2014-12-11

    We report on the first measurement of the azimuthal anisotropy (v₂) of dielectrons (e⁺e⁻ pairs) at mid-rapidity from √(sNN)=200 GeV Au + Au collisions with the STAR detector at the Relativistic Heavy Ion Collider (RHIC), presented as a function of transverse momentum (pT) for different invariant-mass regions. In the mass region Mee<1.1 GeV/c² the dielectron v₂ measurements are found to be consistent with expectations from π⁰,η,ω, and Φ decay contributions. In the mass region 1.1ee<2.9GeV/c², the measured dielectron v₂ is consistent, within experimental uncertainties, with that from the cc¯ contributions.

  3. Beam-Energy Dependence of Charge Separation along the Magnetic Field in Au +Au Collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Contin, G.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Olvitt, D. L.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, J. L.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2014-08-01

    Local parity-odd domains are theorized to form inside a quark-gluon plasma which has been produced in high-energy heavy-ion collisions. The local parity-odd domains manifest themselves as charge separation along the magnetic field axis via the chiral magnetic effect. The experimental observation of charge separation has previously been reported for heavy-ion collisions at the top RHIC energies. In this Letter, we present the results of the beam-energy dependence of the charge correlations in Au +Au collisions at midrapidity for center-of-mass energies of 7.7, 11.5, 19.6, 27, 39, and 62.4 GeV from the STAR experiment. After background subtraction, the signal gradually reduces with decreased beam energy and tends to vanish by 7.7 GeV. This implies the dominance of hadronic interactions over partonic ones at lower collision energies.

  4. ΔϕΔη correlations in central Au+Au collisions at sNN=200 GeV

    NASA Astrophysics Data System (ADS)

    Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D.; Anderson, M.; Arkhipkin, D.; Averichev, G. S.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Bekele, S.; Belaga, V. V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Bezverkhny, B. I.; Bharadwaj, S.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Blyth, C. O.; Blyth, S.-L.; Bonner, B. E.; Botje, M.; Bouchet, J.; Brandin, A. V.; Bravar, A.; Bystersky, M.; Cadman, R. V.; Cai, X. Z.; Caines, H.; Sánchez, M. Calderón De La Barca; Castillo, J.; Catu, O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, H. A.; Christie, W.; Coffin, J. P.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Das, S.; Daugherity, M.; Moura, M. M. De; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; Didenko, L.; Dietel, T.; Djawotho, P.; Dogra, S. M.; Dong, W. J.; Dong, X.; Draper, J. E.; Du, F.; Dunin, V. B.; Dunlop, J. C.; Mazumdar, M. R. Dutta; Eckardt, V.; Edwards, W. R.; Efimov, L. G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C. A.; Gaillard, L.; Gans, J.; Ganti, M. S.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J. E.; Gorbunov, Y. G.; Gos, H.; Grebenyuk, O.; Grosnick, D.; Guertin, S. M.; Guimaraes, K. S. F. F.; Guo, Y.; Gupta, N.; Gutierrez, T. D.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; He, W.; Heinz, M.; Henry, T. W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G. W.; Horner, M. J.; Huang, H. Z.; Huang, S. L.; Hughes, E. W.; Humanic, T. J.; Igo, G.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jia, F.; Jiang, H.; Jones, P. G.; Judd, E. G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Khodyrev, V. Yu.; Kim, B. C.; Kiryluk, J.; Kisiel, A.; Kislov, E. M.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kouchpil, V.; Kowalik, K. L.; Kramer, M.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Kuhn, C.; Kulikov, A. I.; Kumar, A.; Kuznetsov, A. A.; Lamont, M. A. C.; Landgraf, J. M.; Lange, S.; Lapointe, S.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Lehocka, S.; Levine, M. J.; Li, C.; Li, Q.; Li, Y.; Lin, G.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Liu, Z.; Ljubicic, T.; Llope, W. J.; Long, H.; Longacre, R. S.; Lopez-Noriega, M.; Love, W. A.; Lu, Y.; Ludlam, T.; Lynn, D.; Ma, G. L.; Ma, J. G.; Ma, Y. G.; Magestro, D.; Mahapatra, D. P.; Majka, R.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Martin, L.; Matis, H. S.; Matulenko, Yu. A.; McClain, C. J.; McShane, T. S.; Melnick, Yu.; Meschanin, A.; Miller, M. L.; Minaev, N. G.; Mioduszewski, S.; Mironov, C.; Mischke, A.; Mishra, D. K.; Mitchell, J.; Mohanty, B.; Molnar, L.; Moore, C. F.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Netrakanti, P. K.; Nikitin, V. A.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okorokov, V.; Oldenburg, M.; Olson, D.; Pachr, M.; Pal, S. K.; Panebratsev, Y.; Panitkin, S. Y.; Pavlinov, A. I.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Petrov, V. A.; Phatak, S. C.; Picha, R.; Planinic, M.; Pluta, J.; Poljak, N.; Porile, N.; Porter, J.; Poskanzer, A. M.; Potekhin, M.; Potrebenikova, E.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Putschke, J.; Rakness, G.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Razin, S. V.; Reinnarth, J.; Relyea, D.; Retiere, F.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Sahoo, R.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarsour, M.; Sazhin, P. S.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Schweda, K.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shen, W. Q.; Shimanskiy, S. S.; Sichtermann, E.; Simon, F.; Singaraju, R. N.; Smirnov, N.; Snellings, R.; Sood, G.; Sorensen, P.; Sowinski, J.; Speltz, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, T. D. S.; Stock, R.; Stolpovsky, A.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Sugarbaker, E.; Sumbera, M.; Sun, Z.; Surrow, B.; Swanger, M.; Symons, T. J. M.; Toledo, A. Szanto De; Tai, A.; Takahashi, J.; Tang, A. H.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Timmins, A. R.; Timoshenko, S.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; Buren, G. Van; Kolk, N. Van Der; Leeuwen, M. Van; Molen, A. M. Vander; Varma, R.; Vasilevski, I. M.; Vasiliev, A. N.; Vernet, R.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Waggoner, W. T.; Wang, F.; Wang, G.; Wang, J. S.; Wang, X. L.; Wang, Y.; Watson, J. W.; Webb, J. C.; Westfall, G. D.; Wetzler, A.; , C. Whitten, Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wood, J.; Wu, J.; Xu, N.; Xu, Q. H.; Xu, Z.; Yepes, P.; Yoo, I.-K.; Yurevich, V. I.; Zhan, W.; Zhang, H.; Zhang, W. M.; Zhang, Y.; Zhang, Z. P.; Zhao, Y.; Zhong, C.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zubarev, A. N.; Zuo, J. X.

    2007-03-01

    We report charged particle pair correlation analyses in the space of Δϕ (azimuth) and Δη (pseudorapidity), for central Au+Au collisions at sNN=200 GeV in the STAR detector. The analysis involves unlike-sign charged pairs and like-sign charged pairs, which are transformed into charge-dependent (CD) signals and charge-independent (CI) signals. We present detailed parametrizations of the data. A model featuring dense gluonic hot spots as first proposed by Van Hove predicts that the observables under investigation would have sensitivity to such a substructure should it occur, and the model also motivates selection of transverse momenta in the range 0.8

  5. Evidence for bioavailability of Au nanoparticles from soil and biodistribution within earthworms (Eisenia fetida).

    PubMed

    Unrine, Jason M; Hunyadi, Simona E; Tsyusko, Olga V; Rao, William; Shoults-Wilson, W Aaron; Bertsch, Paul M

    2010-11-01

    Because Au nanoparticles (NPs) are resistant to oxidative dissolution and are easily detected, they have been used as stable probes for the behavior of nanomaterials within biological systems. Previous studies provide somewhat limited evidence for bioavailability of Au NPs in food webs, because the spatial distribution within tissues and the speciation of Au was not determined. In this study, we provide multiple lines of evidence, including orthogonal microspectroscopic techniques, as well as evidence from biological responses, that Au NPs are bioavailable from soil to a model detritivore (Eisenia fetida). We also present limited evidence that Au NPs may cause adverse effects on earthworm reproduction. This is perhaps the first study to demonstrate that Au NPs can be taken up by detritivores from soil and distributed among tissues. We found that primary particle size (20 or 55 nm) did not consistently influence accumulated concentrations on a mass concentration basis; however, on a particle number basis the 20 nm particles were more bioavailable. Differences in bioavailability between the treatments may have been explained by aggregation behavior in pore water. The results suggest that nanoparticles present in soil from activities such as biosolids application have the potential to enter terrestrial food webs. PMID:20879765

  6. Evidence for Bioavailability of Au Nanoparticles from Soil and Biodistribution within Earthworms (Eisenia fetida)

    SciTech Connect

    J Unrine; S Hunyadi; O Tsyusko; W Rao; A Shoults-Wilson; P Bertsch

    2011-12-31

    Because Au nanoparticles (NPs) are resistant to oxidative dissolution and are easily detected, they have been used as stable probes for the behavior of nanomaterials within biological systems. Previous studies provide somewhat limited evidence for bioavailability of Au NPs in food webs, because the spatial distribution within tissues and the speciation of Au was not determined. In this study, we provide multiple lines of evidence, including orthogonal microspectroscopic techniques, as well as evidence from biological responses, that Au NPs are bioavailable from soil to a model detritivore (Eisenia fetida). We also present limited evidence that Au NPs may cause adverse effects on earthworm reproduction. This is perhaps the first study to demonstrate that Au NPs can be taken up by detritivores from soil and distributed among tissues. We found that primary particle size (20 or 55 nm) did not consistently influence accumulated concentrations on a mass concentration basis; however, on a particle number basis the 20 nm particles were more bioavailable. Differences in bioavailability between the treatments may have been explained by aggregation behavior in pore water. The results suggest that nanoparticles present in soil from activities such as biosolids application have the potential to enter terrestrial food webs.

  7. 100-MeV proton beam intensity measurement by Au activation analysis using 197Au(p, pn)196Au and 197Au(p, p3n)194Au reactions

    NASA Astrophysics Data System (ADS)

    Mokhtari Oranj, Leila; Jung, Nam-Suk; Oh, Joo-Hee; Lee, Hee-Seock

    2016-05-01

    The proton beam intensity of a 100-MeV proton linac at the Korea Multi-purpose Accelerator Complex (KOMAC) was measured by an Au activation analysis using 197Au(p, pn)196Au and 197Au(p, p3n)194Au reactions to determine the accuracy and precision of beam intensity measurement using Gafchromic film dosimetry method. The target, irradiated by 100-MeV protons, was arranged in a stack consisting of Au, Al foils and Pb plates. The yields of produced radio-nuclei in Au foils were obtained by gamma-ray spectroscopy. The FLUKA code was employed to calculate the energy spectrum of protons onto the front surface of Au foils located at three different depth points of the target and also to investigate the condition of incident beam on the target. A good agreement was found between the beam intensity measurements using the activation analysis method at three different depth points of the target. An excellent agreement was also observed between the beam intensity measurements using the Au activation analysis method and the dosimetry method using Gafchromic film.

  8. Synthesis of vinyl-terminated Au nanoprisms and nanooctahedra mediated by 3-butenoic acid: direct Au@pNIPAM fabrication with improved SERS capabilities.

    PubMed

    Casado-Rodriguez, M A; Sanchez-Molina, M; Lucena-Serrano, A; Lucena-Serrano, C; Rodriguez-Gonzalez, B; Algarra, M; Diaz, A; Valpuesta, M; Lopez-Romero, J M; Perez-Juste, J; Contreras-Caceres, R

    2016-02-28

    Here we describe the first seedless synthesis of vinyl-terminated Au nanotriangular prisms (AuNTPs) and nanooctahedra (AuNOC) in aqueous media. This synthesis is performed by chemical reduction of chloroauric acid (HAuCl4) with 3-butenoic acid (3BA) in the presence of benzyldimethylammonium chloride (BDAC). The principal novelties of the presented method are the use of a mixture of 3BA and BDAC, the synthesis of gold prisms and octahedra with controllable size, and the presence of terminal double bonds on the metal surface. Initially this method produces a mixture of triangular gold nanoprisms and octahedra; however, both morphologies are successfully separated by surfactant micelle induced depletion interaction, reaching percentages up to ∼90%. Moreover, the alkene moieties present on the gold surface are exploited for the fabrication of hybrid core@shell particles. Gold octahedra and triangular prisms are easily encapsulated by free radical polymerization of N-isopropylacrylamide (NIPAM). Finally, in order to obtain a gold core with the most number of tips, AuNTP@pNIPAM microgels were subjected to gold core overgrowth, thus resulting in star-shaped nanoparticles (AuSTs@pNIPAM). We use 4-amino-benzenethiol as the model analyte for SERS investigations. As expected, gold cores with tips and high curvature sites produced the highest plasmonic responses. PMID:26822759

  9. Probing the interstellar medium with pulsars on AU scales

    NASA Technical Reports Server (NTRS)

    Frail, Dale A.; Weisberg, Joel M.; Cordes, James M.; Mathers, Corey

    1994-01-01

    We present a new technique, multiepoch observations of 21 cm absorption against high-velocity pulsars, to probe the properties of the cold neutral hydrogen gas (H I) in the interstellar medium (ISM) at AU scales. In three epochs, over a 1.7 yr interval, we find evidence for significant opacity variations toward all of the pulsars in our sample. Small-scale structure in the ISM is detected on a range of scales from 5 AU to 100 AU, over a wide range of distances (50-2600 pc), opacities (tau(sub max) = 0.1 - 2.5) and directions (anticenter, interarm, high latitude, and local ISM). It appears that small-scale structure is a general property of the ISM and is not confined to special lines of sight. A significant fraction (10%-15%) of the cold H I gas is in this form. These opacity variations do not show any strong correlations with such parameters as transverse distance or integrated opacity, and there is no obvious relation between these structures and those seen in the ionized phase of the ISM.

  10. Fe/Au Core-Shell Nanoparticles for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Sra, Amandeep; Leslie-Pelecky, Diandra

    2009-10-01

    The physical properties of nanoparticles, including size, composition and surface chemistry, greatly influence biological and pharmacological properties and, ultimately, their clinical applications. Superparamagnetic iron oxide nanoparticles are widely used for applications such as MRI contrast agents, drug delivery via magnetic targeting and hyperthermia due to their chemical stability and biocompatibility; however, enhancing the saturation magnetization (Ms) of nanoparticles would produce greater sensitivity. Our design strategy involves a bottom-up wet chemistry approach to the synthesis of Fe nanoparticles. Specific advantages of Fe are the high value of Ms (210 emu/g in bulk) coupled with low toxicity; however, Fe nanoparticles must be protected from oxidation, which causes a dramatic reduction in Ms. To circumvent oxidation, Fe nanoparticles are coated with a Au shell that prevents the oxidation of the magnetic core and also provides the nanoparticles with plasmonic properties for optical stimulation. Ligands of various functionalities can be introduced through the well established Au-thiol surface chemistry for different biomedical applications while maintaining the magnetic functionality of the Fe core. In this presentation, we will discuss the physical, chemical and magnetic properties of our Fe/Au nanoparticles and their resistance to oxidation.

  11. EVENT STRUCTURE AT RHIC FROM P-P TO AU-AU.

    SciTech Connect

    TRAINOR,T.A.

    2004-03-15

    Several correlation analysis techniques are applied to p-p and Au-Au collisions at RHIC. Strong large-momentum-scale correlations are observed which can be related to local charge and momentum conservation during hadronization and to minijet (minimum-bias parton fragment) correlations.

  12. Using supported Au nanoparticles as starting material for preparing uniform Au/Pd bimetallic catalysts

    SciTech Connect

    Villa, Alberto; Prati, Laura; Su, Dangshen; Wang, Di; Veith, Gabriel M

    2010-01-01

    One of the best methods for producing bulk homogeneous (composition) supported bimetallic AuPd clusters involves the immobilization of a protected Au seed followed by the addition of Pd. This paper investigates the importance of this gold seed in controlling the resulting bimetallic AuPd clusters structures, sizes and catalytic activities by investigating three different gold seeds. Uniform Au-Pd alloy were obtained when a steric/electrostatic protecting group, poly(vinyl alcohol) (PVA), was used to form the gold clusters on activated carbon (AC). In contrast Au/AC precursors prepared using Au nanoparticles with only electrostatic stabilization (tetrakis(hydroxypropyl)phosphonium chloride (THPC)), or no stabilization (magnetron sputtering) produced inhomogeneous alloys and segregation of the gold and palladium. The uniform alloyed catalyst (Pd{at}Au{sub PVA}/AC) is the most active and selective catalyst, while the inhomogenous catalysts are less active and selective. Further study of the PVA protected Au clusters revealed that the amount of PVA used is also critical for the preparation of uniform alloyed catalyst, their stability, and their catalytic activity.

  13. Electrochemical Characterization of Protein Adsorption onto YNGRT-Au and VLGXE-Au Surfaces.

    PubMed

    Trzeciakiewicz, Hanna; Esteves-Villanueva, Jose; Soudy, Rania; Kaur, Kamaljit; Martic-Milne, Sanela

    2015-01-01

    The adsorption of the proteins CD13, mucin and bovine serum albumin on VLGXE-Au and YNGRT-Au interfaces was monitored by electrochemical impedance spectroscopy in the presence of [Fe(CN)6](3-/4-). The hydrophobicity of the Au surface was tailored using specific peptides, blocking agents and diluents. The combination of blocking agents (ethanolamine or n-butylamine) and diluents (hexanethiol or 2-mercaptoethanol) was used to prepare various peptide-modified Au surfaces. Protein adsorption onto the peptide-Au surfaces modified with the combination of n-butylamine and hexanethiol produced a dramatic decrease in the charge transfer resistance, Rct, for all three proteins. In contrast, polar peptide-surfaces induced a minimal change in Rct for all three proteins. Furthermore, an increase in Rct was observed with CD13 (an aminopeptidase overexpressed in certain cancers) in comparison to the other proteins when the VLGXE-Au surface was modified with n-butylamine as a blocking agent. The electrochemical data indicated that protein adsorption may be modulated by tailoring the peptide sequence on Au surfaces and that blocking agents and diluents play a key role in promoting or preventing protein adsorption. The peptide-Au platform may also be used for targeting cancer biomarkers with designer peptides. PMID:26262621

  14. The extraction characteristic of Au-Ag from Au concentrate by thiourea solution

    NASA Astrophysics Data System (ADS)

    Kim, Bongju; Cho, Kanghee; On, Hyunsung; Choi, Nagchoul; Park, Cheonyoung

    2013-04-01

    The cyanidation process has been used commercially for the past 100 years, there are ores that are not amenable to treatment by cyanide. Interest in alternative lixiviants, such as thiourea, halogens, thiosulfate and malononitrile, has been revived as a result of a major increase in gold price, which has stimulated new developments in extraction technology, combined with environmental concern. The Au extraction process using the thiourea solvent has many advantages over the cyanidation process, including higher leaching rates, faster extraction time and less than toxicity. The purpose of this study was investigated to the extraction characteristic of Au-Ag from two different Au concentrate (sulfuric acid washing and roasting) under various experiment conditions (thiourea concentration, pH of solvent, temperature) by thiourea solvent. The result of extraction experiment showed that the Au-Ag extraction was a fast extraction process, reaching equilibrium (maximum extraction rate) within 30 min. The Au-Ag extraction rate was higher in the roasted concentrate than in the sulfuric acid washing. The higher the Au-Ag extraction rate (Au - 70.87%, Ag - 98.12%) from roasted concentrate was found when the more concentration of thiourea increased, pH decreased and extraction temperature increased. This study informs extraction method basic knowledge when thiourea was a possibility to eco-/economic resources of Au-Ag utilization studies including the hydrometallurgy.

  15. Electrochemical Characterization of Protein Adsorption onto YNGRT-Au and VLGXE-Au Surfaces

    PubMed Central

    Trzeciakiewicz, Hanna; Esteves-Villanueva, Jose; Soudy, Rania; Kaur, Kamaljit; Martic-Milne, Sanela

    2015-01-01

    The adsorption of the proteins CD13, mucin and bovine serum albumin on VLGXE-Au and YNGRT-Au interfaces was monitored by electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3−/4−. The hydrophobicity of the Au surface was tailored using specific peptides, blocking agents and diluents. The combination of blocking agents (ethanolamine or n-butylamine) and diluents (hexanethiol or 2-mercaptoethanol) was used to prepare various peptide-modified Au surfaces. Protein adsorption onto the peptide-Au surfaces modified with the combination of n-butylamine and hexanethiol produced a dramatic decrease in the charge transfer resistance, Rct, for all three proteins. In contrast, polar peptide-surfaces induced a minimal change in Rct for all three proteins. Furthermore, an increase in Rct was observed with CD13 (an aminopeptidase overexpressed in certain cancers) in comparison to the other proteins when the VLGXE-Au surface was modified with n-butylamine as a blocking agent. The electrochemical data indicated that protein adsorption may be modulated by tailoring the peptide sequence on Au surfaces and that blocking agents and diluents play a key role in promoting or preventing protein adsorption. The peptide-Au platform may also be used for targeting cancer biomarkers with designer peptides. PMID:26262621

  16. Observation of anisotropic event shapes and transverse flow in ultrarelativistic Au+Au collisions

    SciTech Connect

    Barrette, J.; Bellwied, R.; Bennett, S.; Braun-Munzinger, P.; Cleland, W.E.; Clemen, M.; Cole, J.; Cormier, T.M.; David, G.; Dee, J.; Dietzsch, O.; Drigert, M.; Gilbert, S.; Hall, J.R.; Hemmick, T.K.; Herrmann, N.; Hong, B.; Jiang, C.L.; Kwon, Y.; Lacasse, R.; Lukaszew, A.; Li, Q.; Ludlam, T.W.; McCorkle, S.; Mark, S.K.; Matheus, R.; O'Brien, E.; Panitkin, S.; Piazza, T.; Pruneau, C.; Rao, M.N.; Rosati, M.; daSilva, N.C.; Sedykh, S.; Sonnadara, U.; Stachel, J.; Takai, H.; Takagui, E.M.; Voloshin, S.; Wang, G.; Wessels, J.P.; Woody, C.L.; Xu, N.; Zhang, Y.; Zhang, Z.; Zou, C. Gesellschaft fuer Schwerionenforschung, Darmstadt Idaho National Engineering Laboratory, Idaho Falls, Idaho 83402 McGill Univesity, Montreal, H3A 2T8 University of Pittsburgh, Pittsburgh, Pennsylvania 15260 SUNY, Stony Brook, New York, 11794 University of Sao Paulo, Sao Paulo

    1994-11-07

    Event shapes for Au + Au collisions at 11.4 GeV/[ital c] per nucleon were studied over nearly the full solid angle with the E877 apparatus. The analysis was performed by Fourier expansion of azimuthal distributions of the transverse energy ([ital E][sub [ital T

  17. Systematics of Fragment Spectra and Collective Motion in Au + Au Collisions

    NASA Astrophysics Data System (ADS)

    Keane, Declan

    1998-04-01

    The importance of comprehensive data on single-particle spectra and collective motion has been recognized for many years. The literature contains many references to the need for full ``triple-differential cross section" measurements (d^3σ/dp_⊥ dy dφr , or their equivalent, where φr signifies azimuth relative to the event reaction plane). There are grounds for arguing that talk about triple-differential cross sections is misleading in this context, because the ideal measurements for constraining models in fact resemble eighth-order differentials d^8 σ / dp_⊥ dy dφr dM dm_frag dAt dAp dE_p, where M is a measure of event centrality (e.g., multiplicity), m_frag steps through the possible fragment species, and the subscripts t and p refer to target and projectile, respectively. The ideal goal of a meaningful measurement of the full parameter space in principle requires prohibitively large statistics, and even if those statistics were available, many millions of spectra would be needed to present the eighth-order differential cross sections. In practice, the problem is manageable because the structure of the events in the eight-dimensional parameter space is not nearly as complex as it could be in principle, and a relatively simple phenomenological framework can describe all the known relevant features of the events. The above points will be discussed mostly in the context of measurements of Au + Au data from the EOS Time Projection Chamber at beam energies of 0.25A GeV and above.

  18. Dielectron production in Au + Au collisions at √{sN N}=200 GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alexander, J.; Alfred, M.; Al-Ta'Ani, H.; Angerami, A.; Aoki, K.; Apadula, N.; Aramaki, Y.; Asano, H.; Aschenauer, E. C.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bandara, N. S.; Bannier, B.; Barish, K. N.; Bassalleck, B.; Bathe, S.; Baublis, V.; Baumgart, S.; Bazilevsky, A.; Beaumier, M.; Beckman, S.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Bryslawskyj, J.; Buesching, H.; Bumazhnov, V.; Butsyk, S.; Campbell, S.; Castera, P.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Csanád, M.; Csörgő, T.; Dairaku, S.; Danley, T. W.; Datta, A.; Daugherity, M. S.; David, G.; Deblasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Ding, L.; Dion, A.; Diss, P. B.; Do, J. H.; Donadelli, M.; D'Orazio, L.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Edwards, S.; Efremenko, Y. V.; Engelmore, T.; Enokizono, A.; Esumi, S.; Eyser, K. O.; Fadem, B.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fusayasu, T.; Gainey, K.; Gal, C.; Gallus, P.; Garg, P.; Garishvili, A.; Garishvili, I.; Ge, H.; Giordano, F.; Glenn, A.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Guo, L.; Gustafsson, H.-Å.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamilton, H. F.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Haseler, T. O. S.; Hashimoto, K.; Haslum, E.; Hayano, R.; He, X.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Horaguchi, T.; Hori, Y.; Hoshino, T.; Hotvedt, N.; Huang, J.; Huang, S.; Ichihara, T.; Iinuma, H.; Ikeda, Y.; Imai, K.; Imrek, J.; Inaba, M.; Iordanova, A.; Isenhower, D.; Issah, M.; Ivanishchev, D.; Jacak, B. V.; Javani, M.; Jezghani, M.; Jia, J.; Jiang, X.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kamin, J.; Kanda, S.; Kaneti, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Key, J. A.; Khachatryan, V.; Khanzadeev, A.; Kijima, K. M.; Kim, B. I.; Kim, C.; Kim, D. J.; Kim, E.-J.; Kim, G. W.; Kim, H. J.; Kim, K.-B.; Kim, M.; Kim, Y.-J.; Kim, Y. K.; Kimelman, B.; Kinney, E.; Kiss, Á.; Kistenev, E.; Kitamura, R.; Klatsky, J.; Kleinjan, D.; Kline, P.; Koblesky, T.; Komatsu, Y.; Komkov, B.; Koster, J.; Kotchetkov, D.; Kotov, D.; Král, A.; Krizek, F.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, B.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S.; Lee, S. H.; Lee, S. R.; Leitch, M. J.; Leite, M. A. L.; Leitgab, M.; Lewis, B.; Li, X.; Lim, S. H.; Linden Levy, L. A.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; Masumoto, S.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Meles, A.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyachi, Y.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Mohapatra, S.; Montuenga, P.; Moon, H. J.; Moon, T.; Morrison, D. P.; Motschwiller, S.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagae, T.; Nagamiya, S.; Nagashima, K.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Nederlof, A.; Netrakanti, P. K.; Nihashi, M.; Niida, T.; Nishimura, S.; Nouicer, R.; Novák, T.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Okada, K.; Orjuela Koop, J. D.; Osborn, J. D.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, B. H.; Park, I. H.; Park, J. S.; Park, S.; Park, S. K.; Pate, S. F.; Patel, L.; Patel, M.; Pei, H.; Peng, J.-C.; Pereira, H.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perry, J.; Petti, R.; Pinkenburg, C.; Pinson, R.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Qu, H.; Rak, J.; Ramson, B. J.; Ravinovich, I.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Richardson, E.; Rinn, T.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Rubin, J. G.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sano, M.; Sarsour, M.; Sato, S.; Sawada, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seidl, R.; Sen, A.; Seto, R.; Sett, P.; Sexton, A.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Snowball, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Sziklai, J.; Takagui, E. M.; Takahara, A.; Taketani, A.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tennant, E.; Themann, H.; Tieulent, R.; Timilsina, A.; Todoroki, T.; Tomášek, L.; Tomášek, M.; Torii, H.; Towell, C. L.; Towell, R.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Tsuji, T.; Vale, C.; van Hecke, H. W.; Vargyas, M.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Virius, M.; Vossen, A.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Wei, R.; White, A. S.; White, S. N.; Winter, D.; Wolin, S.; Woody, C. L.; Wysocki, M.; Xia, B.; Xue, L.; Yalcin, S.; Yamaguchi, Y. L.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; Yoo, J. H.; Yoon, I.; You, Z.; Younus, I.; Yu, H.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.; Zou, L.; Phenix Collaboration

    2016-01-01

    We present measurements of e+e- production at midrapidity in Au +Au collisions at √{sNN}=200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass (me e<5 GeV /c2) and pair transverse momentum (pT<5 GeV /c ) for minimum bias and for five centrality classes. The e+e- yield is compared to the expectations from known sources. In the low-mass region (me e=0.30 - 0.76 GeV /c2 ) there is an enhancement that increases with centrality and is distributed over the entire pair pT range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to 2.3 ±0.4 (stat )±0.4 (syst )±0.2 (model ) or to 1.7 ±0.3 (stat )±0.3 (syst )±0.2 (model ) for minimum bias collisions when the open heavy-flavor contribution is calculated with pythia or mc@nlo, respectively. The inclusive mass and pT distributions, as well as the centrality dependence, are well reproduced by model calculations where the enhancement mainly originates from the melting of the ρ meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region (me e=1.2 - 2.8 GeV /c2 ), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.

  19. Intriguing centrality dependence of the Au-Au source size at the AGS

    SciTech Connect

    Baker, M.D.; The E802 Collaboration

    1996-06-01

    One of the main goals of high energy heavy ion physics is to establish the existence of a deconfined phase of nuclear matter--the quark-gluon plasma--at high temperatures or densities. One possible signature of such a phase transition, especially if it were first order, would be a larger source size or lifetime than a similar hadronic system. At current AGS energies, we attempt to form a quark- gluon plasma by achieving a high baryon density for a period of time in the center of the collision region. For a given density threshold, the size of this high density region should be a strong function of the impact parameter: the more central the event, the larger the high density region. Therefore, one possible signature of a quark-gluon plasma would be a sudden change in system lifetime or size as a function of the centrality of the collision. In this talk we present an intriguing effect which was not predicted for simple hadronic systems: a rapid increase of the HBT-measured source radius parameter for pion pairs with increasing centrality for Au-Au collisions at a beam momentum of 11.45 A GeV/c on a fixed target. Experience has shown, however, that we must be cautious in our interpretation. A complete understanding of the collision dynamics at a given energy must be built up from several measurements and new, but conventional, hadronic explanations must be considered for such unexpected effects. More study is needed, therefore, before any strong conclusions can be reached.

  20. Dielectron production in Au plus Au collisions at root s(NN)=200 GeV

    SciTech Connect

    Adare, A.; Awes, Terry C; Cianciolo, Vince; Efremenko, Yuri V; Enokizono, A.; Silvermyr, D.; Sorensen, Soren P; Stankus, Paul W; Young, Glenn R; PHENIX, Collaboration [

    2016-01-01

    We present measurements of e(+)e-production at midrapidity in Au + Au collisions at root s(NN) = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass (m(ee) < 5 GeV/c(2)) and pair transverse momentum (p(T) < 5 GeV/c) for minimum bias and for five centrality classes. The e(+)e(-) yield is compared to the expectations from known sources. In the low-mass region (m(ee) = 0.30-0.76 GeV/c(2)) there is an enhancement that increases with centrality and is distributed over the entire pair p(T) range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to 2.3 +/- 0.4(stat) +/- 0.4(syst) +/- 0.2(model) or to 1.7 +/- 0.3(stat) +/- 0.3(syst) +/- 0.2(model) for minimum bias collisions when the open heavy-flavor contribution is calculated with PYTHIA or MC@NLO, respectively. The inclusive mass and p(T) distributions, as well as the centrality dependence, are well reproduced by model calculations where the enhancement mainly originates from the melting of the rho meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region (m(ee) = 1.2-2.8 GeV/c(2)), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.

  1. Dielectron production in Au plus Au collisions at root s(NN)=200 GeV

    DOE PAGESBeta

    Adare, A.; Awes, Terry C; Cianciolo, Vince; Efremenko, Yuri V; Enokizono, A.; Read, K. F.; Silvermyr, D.; Sorensen, Soren P; Stankus, Paul W; Young, Glenn R; et al

    2016-01-01

    We present measurements of e(+)e-production at midrapidity in Au + Au collisions at root s(NN) = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass (m(ee) < 5 GeV/c(2)) and pair transverse momentum (p(T) < 5 GeV/c) for minimum bias and for five centrality classes. The e(+)e(-) yield is compared to the expectations from known sources. In the low-mass region (m(ee) = 0.30-0.76 GeV/c(2)) there is an enhancement that increases with centrality and is distributed over the entire pair p(T) range measured. It is significantly smaller than previously reported by themore » PHENIX experiment and amounts to 2.3 +/- 0.4(stat) +/- 0.4(syst) +/- 0.2(model) or to 1.7 +/- 0.3(stat) +/- 0.3(syst) +/- 0.2(model) for minimum bias collisions when the open heavy-flavor contribution is calculated with PYTHIA or MC@NLO, respectively. The inclusive mass and p(T) distributions, as well as the centrality dependence, are well reproduced by model calculations where the enhancement mainly originates from the melting of the rho meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region (m(ee) = 1.2-2.8 GeV/c(2)), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.« less

  2. The role of plasmons and interband transitions in the color of AuAl2, AuIn2, and AuGa2

    NASA Astrophysics Data System (ADS)

    Keast, V. J.; Birt, K.; Koch, C. T.; Supansomboon, S.; Cortie, M. B.

    2011-09-01

    First principles calculations of the optical properties of the intermetallic compounds AuAl2, AuIn2, and AuGa2 have been performed. Analysis of the dielectric functions showed that AuAl2 is unique because a bulk plasmon is seen in the optical region and contributes to the purple color of this material. An experimental electron energy-loss spectrum showed excellent agreement with the theoretical prediction and confirmed the presence of the bulk plasmon.

  3. Microbial synthesis of Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites for catalytic reduction of nitroaromatic compounds

    PubMed Central

    Tuo, Ya; Liu, Guangfei; Dong, Bin; Zhou, Jiti; Wang, Aijie; Wang, Jing; Jin, Ruofei; Lv, Hong; Dou, Zeou; Huang, Wenyu

    2015-01-01

    Magnetically recoverable noble metal nanoparticles are promising catalysts for chemical reactions. However, the chemical synthesis of these nanocatalysts generally causes environmental concern due to usage of toxic chemicals under extreme conditions. Here, Pd/Fe3O4, Au/Fe3O4 and PdAu/Fe3O4 nanocomposites are biosynthesized under ambient and physiological conditions by Shewanella oneidensis MR-1. Microbial cells firstly transform akaganeite into magnetite, which then serves as support for the further synthesis of Pd, Au and PdAu nanoparticles from respective precursor salts. Surface-bound cellular components and exopolysaccharides not only function as shape-directing agent to convert some Fe3O4 nanoparticles to nanorods, but also participate in the formation of PdAu alloy nanoparticles on magnetite. All these three kinds of magnetic nanocomposites can catalyze the reduction of 4-nitrophenol and some other nitroaromatic compounds by NaBH4. PdAu/Fe3O4 demonstrates higher catalytic activity than Pd/Fe3O4 and Au/Fe3O4. Moreover, the magnetic nanocomposites can be easily recovered through magnetic decantation after catalysis reaction. PdAu/Fe3O4 can be reused in at least eight successive cycles of 4-nitrophenol reduction. The biosynthesis approach presented here does not require harmful agents or rigorous conditions and thus provides facile and environmentally benign choice for the preparation of magnetic noble metal nanocatalysts. PMID:26310728

  4. Measuring the Optical Absorption Cross-sections of Au-Ag Nanocages and Au Nanorods by Photoacoustic Imaging

    PubMed Central

    Cho, Eun Chul; Kim, Chulhong; Zhou, Fei; Cobley, Claire M.; Song, Kwang Hyun; Chen, Jingyi; Li, Zhi-Yuhan; Wang, Lihong V.; Xia, Younan

    2009-01-01

    This paper presents a method for measuring the optical absorption cross-sections (σa) of Au-Ag nanocages and Au nanorods. The method is based on photoacoustic (PA) imaging, where the detected signal is directly proportional to the absorption coefficient (μa) of the nanostructure. For each type of nanostructure, we firstly obtained μa from the PA signal by benchmarking against a linear calibration curve (PA signal vs. μa) derived from a set of methylene blue solutions with different concentrations. We then calculated σa by dividing the μa by the corresponding concentration of the Au nanostructure. Additonally, we obtained the extinction cross-section (σe, sum of absorption and scattering) from the extinction spectrum recorded using a conventional UV-vis-NIR spectrometer. From the measurements of σa and σe, we were able to easily derive both the absorption and scattering cross-sections for each type of gold nanostructure. The ratios of absorption to extinction obtained from experimental and theoretical approaches agreed well, demonstrating the potential use of this method in determining the optical absorption and scattering properties of gold nanostructures and other types of nanomaterials. PMID:19680423

  5. Interaction of HNCO with Au(111) surfaces

    NASA Astrophysics Data System (ADS)

    Farkas, A. P.; Berkó, A.; Solymosi, F.

    2012-08-01

    The surface chemistry of isocyanic acid, HNCO, and its dissociation product, NCO, was studied on clean, O-dosed and Ar ion bombarded Au(111) surfaces. The techniques used are high resolution energy loss spectroscopy (HREELS) and temperature-programmed desorption (TPD). The structure of Ar ion etched surface is explored by scanning tunneling microscopy (STM). HNCO adsorbs molecularly on Au(111) surface at 100 K yielding strong losses at 1390, 2270 and 3230 cm- 1. The weakly adsorbed HNCO desorbs in two peaks characterized by Tp = 130 and 145 K. The dissociation of the chemisorbed HNCO occurs at 150 K to give NCO species characterized by a vibration at 2185 cm- 1. The dissociation process is facilitated by the presence of preadsorbed O and by defect sites on Au(111) produced by Ar ion bombardment. In the latter case the loss feature of NCO appeared at 2130 cm- 1. Isocyanate on Au(111) surface was found to be more stable than on the single crystal surfaces of Pt-group metals. Results are compared with those obtained on supported Au catalysts.

  6. Magnetization dynamics of mixed Co-Au chains on Cu(110) substrate: Combined ab initio and kinetic Monte Carlo study

    NASA Astrophysics Data System (ADS)

    M. Tsysar, K.; V. Kolesnikov, S.; M. Saletsky, A.

    2015-09-01

    We present an investigation of the one-dimensional ferromagnetism in Au-Co nanowires deposited on the Cu(110) surface. By using the density functional theory, the influence of the nonmagnetic copper substrate Cu(110) on the magnetic properties of the bimetallic Au-Co nanowires is studied. The results show the emergence of magnetic anisotropy in the supported Au-Co nanowires. The magnetic anisotropy energy has the same order of magnitude as the exchange interaction energy between Co atoms in the wire. Our electronic structure calculation reveals the emergence of new hybridized bands between Au and Co atoms and surface Cu atoms. The Curie temperature of the Au-Co wires is calculated by means of kinetic Monte Carlo simulation. The strong size effect of the Curie temperature is demonstrated. Project supported by the Russian Foundation of Basic Researches.

  7. Tungsten oxide-Au nanosized film composites for glucose oxidation and sensing in neutral medium

    PubMed Central

    Gougis, Maxime; Ma, Dongling; Mohamedi, Mohamed

    2015-01-01

    In this work, we report for the first time the use of tungsten oxide (WOx) as catalyst support for Au toward the direct electrooxidation of glucose. The nanostructured WOx/Au electrodes were synthesized by means of laser-ablation technique. Both micro-Raman spectroscopy and transmission electron microscopy showed that the produced WOx thin film is amorphous and made of ultrafine particles of subnanometer size. X-ray diffraction and X-ray photoelectron spectroscopy revealed that only metallic Au was present at the surface of the WOx/Au composite, suggesting that the WOx support did not alter the electronic structure of Au. The direct electrocatalytic oxidation of glucose in neutral medium such as phosphate buffered saline (pH 7.2) solution has been investigated with cyclic voltammetry, chronoamperometry, and square-wave voltammetry. Sensitivity as high as 65.7 μA cm−2 mM−1 up to 10 mM of glucose and a low detection limit of 10 μM were obtained with square-wave voltammetry. This interesting analytical performance makes the laser-fabricated WOx/Au electrode potentially promising for implantable glucose fuel cells and biomedical analysis as the evaluation of glucose concentration in biological fluids. Finally, owing to its unique capabilities proven in this work, it is anticipated that the laser-ablation technique will develop as a fabrication tool for chip miniature-sized sensors in the near future. PMID:25931820

  8. Choline-induced selective fluorescence quenching of acetylcholinesterase conjugated Au@BSA clusters.

    PubMed

    Mathew, Meegle S; Baksi, Ananya; Pradeep, T; Joseph, Kuruvilla

    2016-07-15

    We have developed a highly selective sensitive fluorescent detection of acetylcholine (ACh) using bovine serum albumin (BSA) protected atomically precise clusters of gold. The gold quantum clusters (AuQC@BSA) synthesized using bovine serum albumin and conjugated with acetylcholinesterase (AChE), an enzyme specific for acetylcholine, resulting in AuQC@BSA-AChE. The enzyme, AChE hydrolyzes acetylcholine (ACh) to choline (Ch) which in turn interacts with AuQC@BSA-AChE and quenches its fluorescence, enabling sensing. We have carried out the real time monitoring of the hydrolysis of ACh using electrospray ionization mass spectrometry (ESI MS) to find out the mechanism of fluorescent quenching. The validity of present method for determination of concentration of acetylcholine in real system such as blood was demonstrated. Further, the sensor, AuQC@BSA-AChE can be easily coated on paper and an efficient and cheap sensor can be developed and detection limit for ACh is found to be 10nM. The fluorescent intensity of AuQC@BSA-AChE is sensitive towards acetylcholine in range of 10nM to 6.4µM. This suggests that AuQC@BSA-AChE has an excellent potential to be used for diagnosis of various neuropsychological and neuropsychiatric disorders. PMID:26921554

  9. Synthesis and Characterization of Au@Cu Core-Shell Nanoparticles

    NASA Astrophysics Data System (ADS)

    Khanal, Subarna; Velazquez-Salazar, Jesus; Yacaman, Miguel Jose

    2011-10-01

    The synthesis of bimetallic nanoparticles has become so important in present times due to its diverse applications of nanotechnology. Particularly most of the bimetallic nanoparticles are focused to use in catalysis, plasmonic, magnetic, sensors, and many other applications. In Au/Cu case, the bulk Au and Cu are soluble at all compositions. But the structure of Au/Cu nanoparticles depends on the preparation methods. The structure might be the core shell, alloys or other morphology. Au- Cu core-shell nanocrystals were prepared using a two-step polyol reduction method. First, Au core seeds were prepared by reducing HAuCl4. 4H2O in ethylene glycol (EG) using oil-bath heating in the presence of polyvinylpyrrolidone (PVP) as a polymer surfactant. Then Cu shells were overgrown on Au core seeds by reducing Cu2(OAc)4 in EG with PVP again using oil-bath heating. The morphology is studied by STEM HITACHI S-5500.The resultant crystal structures were characterized using TEM, high-resolution (HR)-TEM and the STEM were using for the study of micro analysis.

  10. Cu-Au Alloys Using Monte Carlo Simulations and the BFS Method for Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Good, Brian; Ferrante, John

    1996-01-01

    Semi empirical methods have shown considerable promise in aiding in the calculation of many properties of materials. Materials used in engineering applications have defects that occur for various reasons including processing. In this work we present the first application of the BFS method for alloys to describe some aspects of microstructure due to processing for the Cu-Au system (Cu-Au, CuAu3, and Cu3Au). We use finite temperature Monte Carlo calculations, in order to show the influence of 'heat treatment' in the low-temperature phase of the alloy. Although relatively simple, it has enough features that could be used as a first test of the reliability of the technique. The main questions to be answered in this work relate to the existence of low temperature ordered structures for specific concentrations, for example, the ability to distinguish between rather similar phases for equiatomic alloys (CuAu I and CuAu II, the latter characterized by an antiphase boundary separating two identical phases).

  11. Photoelectrochemical sensing of 4-chlorophenol based on Au/BiOCl nanocomposites.

    PubMed

    Yan, Pengcheng; Xu, Li; Xia, Jiexiang; Huang, Yan; Qiu, Jingxia; Xu, Qian; Zhang, Qi; Li, Huaming

    2016-08-15

    The Au/BiOCl composites have been prepared by a facile one-pot ethylene glycol (EG) assisted solvothermal reaction in the presence of ionic liquid 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl). During the synthesis procedure, the [C16mim]Cl has been used as Cl source, solvent of this system, and dispersing agent to effectively disperse Au on the surface of BiOCl. The as-prepared samples have been systematically characterized by multiple instruments to investigate the structure, morphology, and photoelectrochemical properties. According to the photoelectrochemical data, the Au/BiOCl composites exhibit better photoelectrochemical performance toward the detection of 4-chlorophenol than that of the pure BiOCl. The photocurrent response of Au/BiOCl modified electrode is high and stable under light irradiation. The proposed Au/BiOCl modified electrode shows a wide linear response ranging from 0.16 to 20mgL(-1) with detection limit of 0.05mgL(-1). It indicates a dramatically promising application of bismuth oxyhalides in photoelectrochemical detection. It will be expected that the present study may be lightly extended to the monitor of other organic pollutants by photoelectrochemical detection of the Au/BiOCl composites. PMID:27260461

  12. Descriptive and geoenvironmental model for Co-Cu-Au deposits in metasedimentary rocks: Chapter G in Mineral deposit models for resource assessment

    USGS Publications Warehouse

    Slack, John F.; Johnson, Craig A.; Causey, J. Douglas; Lund, Karen; Schulz, Klaus J.; Gray, John E.; Eppinger, Robert G.

    2013-01-01

    Additional geologically and compositionally similar deposits are known, but have average Co grades less than 0.1 percent. Most of these deposits contain cobalt-rich pyrite and lack appreciable amounts of distinct Co sulfide and (or) sulfarsenide minerals. Such deposits are not discussed in detail in the following sections, but these deposits may be revelant to the descriptive and genetic models presented below. Examples include the Scadding Au-Co-Cu deposit in Ontario, Canada; the Vähäjoki Co-Cu-Au deposit in Finland; the Tuolugou Co-Au deposit in Qinghai Province, China; the Lala Co-Cu-UREE deposit in Sichuan Province, China; the Guelb Moghrein Cu-Au-Co deposit in Mauritania; and the Great Australia Co-Cu, Greenmount Cu-Au-Co, and Monakoff Cu-Au-Co-UAg deposits in Queensland, Australia. Detailed information on these deposits is presented in appendix 2.

  13. Fabrication of bimetallic Cu/Au nanotubes and their sensitive, selective, reproducible and reusable electrochemical sensing of glucose

    NASA Astrophysics Data System (ADS)

    Tee, Si Yin; Ye, Enyi; Pan, Pei Hua; Lee, Coryl Jing Jun; Hui, Hui Kim; Zhang, Shuang-Yuan; Koh, Leng Duei; Dong, Zhili; Han, Ming-Yong

    2015-06-01

    Herein, we report a facile two-step approach to produce gold-incorporated copper (Cu/Au) nanostructures through controlled disproportionation of the Cu+-oleylamine complex at 220 °C to form copper nanowires and the subsequent reaction with Au3+ at different temperatures of 140, 220 and 300 °C. In comparison with copper nanowires, these bimetallic Cu/Au nanostructures exhibit their synergistic effect to greatly enhance glucose oxidation. Among them, the shape-controlled Cu/Au nanotubes prepared at 140 °C show the highest electrocatalytic activity for non-enzymatic glucose sensing in alkaline solution. In addition to high sensitivity and fast response, the Cu/Au nanotubes possess high selectivity against interferences from other potential interfering species and excellent reproducibility with long-term stability. By introducing gold into copper nanostructures at a low level of 3, 1 and 0.1 mol% relative to the initial copper precursor, a significant electrocatalytic enhancement of the resulting bimetallic Cu/Au nanostructures starts to occur at 1 mol%. Overall, the present fabrication of stable Cu/Au nanostructures offers a promising low-cost platform for sensitive, selective, reproducible and reusable electrochemical sensing of glucose.Herein, we report a facile two-step approach to produce gold-incorporated copper (Cu/Au) nanostructures through controlled disproportionation of the Cu+-oleylamine complex at 220 °C to form copper nanowires and the subsequent reaction with Au3+ at different temperatures of 140, 220 and 300 °C. In comparison with copper nanowires, these bimetallic Cu/Au nanostructures exhibit their synergistic effect to greatly enhance glucose oxidation. Among them, the shape-controlled Cu/Au nanotubes prepared at 140 °C show the highest electrocatalytic activity for non-enzymatic glucose sensing in alkaline solution. In addition to high sensitivity and fast response, the Cu/Au nanotubes possess high selectivity against interferences from other

  14. Controlled synthesis and synergistic effects of graphene-supported PdAu bimetallic nanoparticles with tunable catalytic properties

    NASA Astrophysics Data System (ADS)

    Liu, Chang-Hai; Liu, Rui-Hua; Sun, Qi-Jun; Chang, Jian-Bing; Gao, Xu; Liu, Yang; Lee, Shuit-Tong; Kang, Zhen-Hui; Wang, Sui-Dong

    2015-03-01

    Graphene-supported bimetallic nanoparticles are promising nanocatalysts, which can show strong and tunable catalytic activity and selectivity. Herein room-temperature-ionic-liquid-assisted metal sputtering is utilized to synthesize PdAu bimetallic nanoparticles on graphene with bare surface, small size, high surface density and controlled Pd-to-Au ratio. This controllable synthetic approach is green-chemistry compatible and totally free of additives and byproducts. The supported PdAu nanoparticles show excellent catalytic capabilities for both oxidation and reduction reactions, strongly dependent on the Pd-to-Au ratio. A strong correlation among catalytic performance, bimetallic composition and charge redistribution in the PdAu nanoparticles has been demonstrated. The results suggest that sufficient Au d-holes appear to be significant to the catalysis of oxidation reaction, and a metallic Pd surface is critical to the catalysis of reduction reaction. By the present method, the bimetallic combination can be tailored for distinct types of catalytic reactions.Graphene-supported bimetallic nanoparticles are promising nanocatalysts, which can show strong and tunable catalytic activity and selectivity. Herein room-temperature-ionic-liquid-assisted metal sputtering is utilized to synthesize PdAu bimetallic nanoparticles on graphene with bare surface, small size, high surface density and controlled Pd-to-Au ratio. This controllable synthetic approach is green-chemistry compatible and totally free of additives and byproducts. The supported PdAu nanoparticles show excellent catalytic capabilities for both oxidation and reduction reactions, strongly dependent on the Pd-to-Au ratio. A strong correlation among catalytic performance, bimetallic composition and charge redistribution in the PdAu nanoparticles has been demonstrated. The results suggest that sufficient Au d-holes appear to be significant to the catalysis of oxidation reaction, and a metallic Pd surface is critical

  15. Au nanoparticles films used in biological sensing

    NASA Astrophysics Data System (ADS)

    Rosales Pérez, M.; Delgado Macuil, R.; Rojas López, M.; Gayou, V. L.; Sánchez Ramírez, J. F.

    2009-05-01

    Lactobacillus para paracasei are used commonly as functional food and probiotic substances. In this work Au nanoparticles self-assembled films were used for Lactobacillus para paracasei determination at five different concentrations. Functionalized substrates were immersed in a colloidal solution for one and a half hour at room temperature and dried at room temperature during four hours. After that, drops of Lactobacillus para paracasei in aqueous solution were put into the Au nanoparticles film and let dry at room temperature for another two hours. Infrared spectroscopy in attenuated total reflectance sampling mode was used to observe generation peaks due to substrate silanization, enhancement of Si-O band intensity due to the Au colloids added to silanized substrate and also to observe the enhancement of Lactobacillus para paracasei infrared intensity of the characteristic frequencies at 1650, 1534 and 1450 cm-1 due to surface enhancement infrared absorption.

  16. N-Heterocyclic Carbene Ligands for Au Nanocrystal Stabilization and Three-Dimensional Self-Assembly

    PubMed Central

    2016-01-01

    N-Heterocyclic carbenes (NHCs) have emerged as a new class of ligands for materials chemistry that appears particularly relevant for the stabilization and functionalization of metal nanoparticles (NPs). The particular properties and high synthetic flexibility of NHCs make them highly attractive tools for the development of new (nano)materials and the fundamental study of their properties. The relationships between the NHC structure and NP structure/properties, including physical, biological, and self-assembly properties, remain largely unknown. In the past decade, many efforts have been made to gain more fundamental understanding in this area. In this feature article, we present our contribution in this field focusing on the formation of NHC-coated Au nanocrystals (NCs), their stability, and their ability to self-assemble into 3D crystalline structures called supracrystals. First, the formation of NHC-stabilized Au NCs is discussed by comparing different NHC structures, NHC-based Au precursors, and synthesis methods. This study shows the major role of the NHC structure in obtaining both stable NHC-coated Au NCs and narrow size distributions. In a second part, a comparative study of the oxygen resistance of NHC- and thiol-coated NCs is presented, demonstrating the enhanced stability of NHC-coated Au NCs to oxygen-based treatments. Finally, the self-assembly of NHC-coated Au NCs into 3D Au superlattices is presented. The formation of large organized domains of several micrometers is described from the design of NHCs tailored with long alkyl chains. In these different contexts, efforts have been made to gain a more in-depth understanding of the behavior of NHC ligands at the surface of NCs. These results show that the NHC-based approach to nanomaterials has many assets for opening a new research area in the supracrystal world. PMID:27412075

  17. N-Heterocyclic Carbene Ligands for Au Nanocrystal Stabilization and Three-Dimensional Self-Assembly.

    PubMed

    Roland, Sylvain; Ling, Xiang; Pileni, Marie-Paule

    2016-08-01

    N-Heterocyclic carbenes (NHCs) have emerged as a new class of ligands for materials chemistry that appears particularly relevant for the stabilization and functionalization of metal nanoparticles (NPs). The particular properties and high synthetic flexibility of NHCs make them highly attractive tools for the development of new (nano)materials and the fundamental study of their properties. The relationships between the NHC structure and NP structure/properties, including physical, biological, and self-assembly properties, remain largely unknown. In the past decade, many efforts have been made to gain more fundamental understanding in this area. In this feature article, we present our contribution in this field focusing on the formation of NHC-coated Au nanocrystals (NCs), their stability, and their ability to self-assemble into 3D crystalline structures called supracrystals. First, the formation of NHC-stabilized Au NCs is discussed by comparing different NHC structures, NHC-based Au precursors, and synthesis methods. This study shows the major role of the NHC structure in obtaining both stable NHC-coated Au NCs and narrow size distributions. In a second part, a comparative study of the oxygen resistance of NHC- and thiol-coated NCs is presented, demonstrating the enhanced stability of NHC-coated Au NCs to oxygen-based treatments. Finally, the self-assembly of NHC-coated Au NCs into 3D Au superlattices is presented. The formation of large organized domains of several micrometers is described from the design of NHCs tailored with long alkyl chains. In these different contexts, efforts have been made to gain a more in-depth understanding of the behavior of NHC ligands at the surface of NCs. These results show that the NHC-based approach to nanomaterials has many assets for opening a new research area in the supracrystal world. PMID:27412075

  18. Au-Ag@Au Hollow Nanostructure with Enhanced Chemical Stability and Improved Photothermal Transduction Efficiency for Cancer Treatment.

    PubMed

    Jiang, Tongtong; Song, Jiangluqi; Zhang, Wenting; Wang, Hao; Li, Xiaodong; Xia, Ruixiang; Zhu, Lixin; Xu, Xiaoliang

    2015-10-01

    Despite the fact that Au-Ag hollow nanoparticles (HNPs) have gained much attention as ablation agents for photothermal therapy, the instability of the Ag element limits their applications. Herein, excess Au atoms were deposited on the surface of a Au-Ag HNP by improving the reduction power of l-ascorbic acid (AA) and thereby preventing the reaction between HAuCl4 and the Ag element in the Au-Ag alloy nanostructure. Significantly, the obtained Au-Ag@Au HNPs show excellent chemical stability in an oxidative environment, together with remarkable increase in extinction peak intensity and obvious narrowing in peak width. Moreover, finite-difference time-domain (FDTD) was used to simulate the optical properties and electric field distribution of HNPs. The calculated results show that the proportion of absorption cross section in total extinction cross section increases with the improvement of Au content in HNP. As predicted by the theoretical calculation results, Au-Ag@Au nanocages (NCs) exhibit a photothermal transduction efficiency (η) as high as 36.5% at 808 nm, which is higher than that of Au-Ag NCs (31.2%). Irradiated by 808 nm laser at power densities of 1 W/cm(2), MCF-7 breast cancer cells incubated with PEGylated Au-Ag@Au NCs were seriously destroyed. Combined together, Au-Ag@Au HNPs with enhanced chemical stability and improved photothermal transduction efficiency show superior competitiveness as photothermal agents. PMID:26371629

  19. Measurement of J/ψ azimuthal anisotropy in Au+Au collisions at sqrt[s(NN)]=200 GeV.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E; Averichev, G S; Balewski, J; Banerjee, A; Barnovska, Z; Beavis, D R; Bellwied, R; Betancourt, M J; Betts, R R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bruna, E; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, J Y; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chung, P; Chwastowski, J; Codrington, M J M; Corliss, R; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Ding, F; Dion, A; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Elnimr, M; Engelage, J; Eppley, G; Eun, L; Evdokimov, O; Fatemi, R; Fazio, S; Fedorisin, J; Fersch, R G; Filip, P; Finch, E; Fisyak, Y; Flores, E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Gliske, S; Grebenyuk, O G; Grosnick, D; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hajkova, O; Hamed, A; Han, L-X; Harris, J W; Hays-Wehle, J P; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jena, C; Judd, E G; Kabana, S; Kang, K; Kapitan, J; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Kikola, D P; Kiryluk, J; Kisel, I; Kisiel, A; Klein, S R; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Korsch, W; Kotchenda, L; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Lamont, M A C; Landgraf, J M; Landry, K D; Lapointe, S; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Leight, W; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lima, L M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Longacre, R S; Lu, Y; Luo, X; Luszczak, A; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Mioduszewski, S; Mitrovski, M K; Mohammed, Y; Mohanty, B; Mondal, M M; Munhoz, M G; Mustafa, M K; Naglis, M; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nogach, L V; Novak, J; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Oliveira, R A N; Olson, D; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Porter, J; Poskanzer, A M; Powell, C B; Pruneau, C; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Ruan, L; Rusnak, J; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandacz, A; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, B; Schmitz, N; Schuster, T R; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shao, M; Sharma, B; Sharma, M; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Desouza, U G; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Suaide, A A P; Suarez, M C; Sumbera, M; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szanto de Toledo, A; Takahashi, J; Tang, A H; Tang, Z; Tarini, L H; Tarnowsky, T; Thomas, J H; Tian, J; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Videbæk, F; Viyogi, Y P; Vokal, S; Voloshin, S A; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, Q; Wang, X L; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, N; Xu, Q H; Xu, W; Xu, Y; Xu, Z; Xue, L; Yang, Y; Yang, Y; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Zawisza, M; Zbroszczyk, H; Zhang, J B; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2013-08-01

    The measurement of J/ψ azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at sqrt[s(NN)]=200 GeV. The measured J/ψ elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10 GeV/c. Our measurement suggests that J/ψ particles with relatively large transverse momenta are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations. PMID:23952389

  20. Centrality and pseudorapidity dependence of elliptic flow for charged hadrons in Au+Au collisions at √(sNN)=200 GeV

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N. K.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Nguyen, M.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steinberg, P.; Stephans, G. S.; Sukhanov, A.; Tang, J.-L.; Tonjes, M. B.; Trzupek, A.; Vale, C. M.; Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wolfs, F. L.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    2005-11-01

    This Rapid Communication describes the measurement of elliptic flow for charged particles in Au+Au collisions at √(sNN)=200 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider. The measured azimuthal anisotropy is presented over a wide range of pseudorapidity for three broad collision centrality classes for the first time at this energy. Two distinct methods of extracting the flow signal were used to reduce systematic uncertainties. The elliptic flow falls sharply with increasing |η| at 200 GeV for all the centralities studied, as observed for minimum-bias collisions at √(sNN)=130 GeV.

  1. Measurement of J/ψ Azimuthal Anisotropy in Au+Au Collisions at √sNN=200 GeV

    DOE PAGESBeta

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; et al

    2013-08-02

    The measurement of J/ψ azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at √sNN>/sub>=200 GeV. The measured J/ψ elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10 GeV/c. Our measurement suggests that J/ψ particles with relatively large transverse momenta are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations.

  2. Measurement of J/ψ Azimuthal Anisotropy in Au+Au Collisions at √sNN=200 GeV

    SciTech Connect

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E.; Averichev, G. S.; Balewski, J.; Banerjee, A.; Barnovska, Z.; Beavis, D. R.; Bellwied, R.; Betancourt, M. J.; Betts, R. R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bruna, E.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Cai, X. Z.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, P.; Chwastowski, J.; Codrington, M. J. M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Ding, F.; Dion, A.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elnimr, M.; Engelage, J.; Eppley, G.; Eun, L.; Evdokimov, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Fersch, R. G.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Gliske, S.; Grebenyuk, O. G.; Grosnick, D.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; Hamed, A.; Han, L-X.; Harris, J. W.; Hays-Wehle, J. P.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jena, C.; Judd, E. G.; Kabana, S.; Kang, K.; Kapitan, J.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Kikola, D. P.; Kiryluk, J.; Kisel, I.; Kisiel, A.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Korsch, W.; Kotchenda, L.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; LaPointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Leight, W.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Lu, Y.; Luo, X.; Luszczak, A.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Mioduszewski, S.; Mitrovski, M. K.; Mohammed, Y.; Mohanty, B.; Mondal, M. M.; Munhoz, M. G.; Mustafa, M. K.; Naglis, M.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nogach, L. V.; Novak, J.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; Olson, D.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Powell, C. B.; Pruneau, C.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Ruan, L.; Rusnak, J.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, B.; Schmitz, N.; Schuster, T. R.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shao, M.; Sharma, B.; Sharma, M.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Whitten, C.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, W.; Xu, Y.; Xu, Z.; Xue, L.; Yang, Y.; Yang, Y.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I-K.; Zawisza, M.; Zbroszczyk, H.; Zhang, J. B.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.

    2013-08-02

    The measurement of J/ψ azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at √sNN>/sub>=200 GeV. The measured J/ψ elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10 GeV/c. Our measurement suggests that J/ψ particles with relatively large transverse momenta are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations.

  3. Pion interferometry in Au+Au and Cu+Cu collisions at {radical}(s{sub NN})=62.4 and 200 GeV

    SciTech Connect

    Abelev, B. I.; Barannikova, O.; Betts, R. R.; Garcia-Solis, E. J.; Hofman, D. J.; Hollis, R. S.; Iordanova, A.; Suarez, M. C.; Aggarwal, M. M.; Bhati, A. K.; Kumar, L.; Pruthi, N. K.; Ahammed, Z.; Chattopadhyay, S.; Mazumdar, M. R. Dutta; Ganti, M. S.; Ghosh, P.; Mohanty, B.; Nayak, T. K.; Pal, S. K.

    2009-08-15

    We present a systematic analysis of two-pion interferometry in Au+Au collisions at {radical}(s{sub NN})=62.4 GeV and Cu+Cu collisions at {radical}(s{sub NN})=62.4 and 200 GeV using the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The multiplicity and transverse momentum dependences of the extracted correlation lengths (radii) are studied. The scaling with charged particle multiplicity of the apparent system volume at final interaction is studied for the RHIC energy domain. The multiplicity scaling of the measured correlation radii is found to be independent of colliding system and collision energy.

  4. Pion Interferometry in Au+Au and Cu+Cu Collisions at sqrt sNN = 62.4 and 200 GeV

    SciTech Connect

    STAR Collaboration; Abelev, B.I.

    2009-08-24

    We present a systematic analysis of two-pion interferometry in Au+Au collisions at {radical}sNN = 62.4 GeV and Cu+Cu collisions at {radical}sNN = 62.4 and 200 GeV using the STAR detector at RHIC. The multiplicity and transverse momentum dependences of the extracted correlation lengths (radii) are studied. The scaling with charged particle multiplicity of the apparent system volume at final interaction is studied for the RHIC energy domain. The multiplicity scaling of the measured correlation radii is found to be independent of colliding system and collision energy.

  5. Measurement of Lambda and Lambda(macro) particles in Au+Au collisions at the square root of S(NN) = 130 GeV.

    PubMed

    Adcox, K; Adler, S S; Ajitanand, N N; Akiba, Y; Alexander, J; Aphecetche, L; Arai, Y; Aronson, S H; Averbeck, R; Awes, T C; Barish, K N; Barnes, P D; Barrette, J; Bassalleck, B; Bathe, S; Baublis, V; Bazilevsky, A; Belikov, S; Bellaiche, F G; Belyaev, S T; Bennett, M J; Berdnikov, Y; Botelho, S; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J; Butsyk, S; Carey, T A; Chand, P; Chang, J; Chang, W C; Chavez, L L; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choudhury, R K; Christ, T; Chujo, T; Chung, M S; Chung, P; Cianciolo, V; Cole, B A; D'Enterria, D G; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dinesh, B V; Drees, A; Durum, A; Dutta, D; Ebisu, K; Efremenko, Y V; el-Chenawi, K; En'yo, H; Esumi, S; Ewell, L; Ferdousi, T; Fields, D E; Fokin, S L; Fraenkel, Z; Franz, A; Frawley, A D; Fung, S-Y; Garpman, S; Ghosh, T K; Glenn, A; Godoi, A L; Goto, Y; Greene, S V; Grosse Perdekamp, M; Gupta, S K; Guryn, W; Gustafsson, H-A; Haggerty, J S; Hamagaki, H; Hansen, A G; Hara, H; Hartouni, E P; Hayano, R; Hayashi, N; He, X; Hemmick, T K; Heuser, J M; Hibino, M; Hill, J C; Ho, D S; Homma, K; Hong, B; Hoover, A; Ichihara, T; Imai, K; Ippolitov, M S; Ishihara, M; Jacak, B V; Jang, W Y; Jia, J; Johnson, B M; Johnson, S C; Joo, K S; Kametani, S; Kang, J H; Kann, M; Kapoor, S S; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D J; Kim, H J; Kim, S Y; Kim, Y G; Kinnison, W W; Kistenev, E; Kiyomichi, A; Klein-Boesing, C; Klinksiek, S; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kotchetkov, D; Kozlov, A; Kroon, P J; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Lauret, J; Lebedev, A; Lee, D M; Leitch, M J; Li, X H; Li, Z; Lim, D J; Liu, M X; Liu, X; Liu, Z; Maguire, C F; Mahon, J; Makdisi, Y I; Manko, V I; Mao, Y; Mark, S K; Markacs, S; Martinez, G; Marx, M D; Masaike, A; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E; Merschmeyer, M; Messer, F; Messer, M; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mühlbacher, F; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagasaka, Y; Nagle, J L; Nakada, Y; Nandi, B K; Newby, J; Nikkinen, L; Nilsson, P; Nishimura, S; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Ono, M; Onuchin, V; Oskarsson, A; Osterman, L; Otterlund, I; Oyama, K; Paffrath, L; Pal, D; Palounek, A P T; Pantuev, V S; Papavassiliou, V; Pate, S F; Peitzmann, T; Petridis, A N; Pinkenburg, C; Pisani, R P; Pitukhin, P; Plasil, F; Pollack, M; Pope, K; Purschke, M L; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Rosati, M; Rose, A A; Ryu, S S; Saito, N; Sakaguchi, A; Sakaguchi, T; Sako, H; Sakuma, T; Samsonov, V; Sangster, T C; Santo, R; Sato, H D; Sato, S; Sawada, S; Schlei, B R; Schutz, Y; Semenov, V; Seto, R; Shea, T K; Shein, I; Shibata, T-A; Shigaki, K; Shiina, T; Shin, Y H; Sibiriak, I G; Silvermyr, D; Sim, K S; Simon-Gillo, J; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sorensen, S; Stankus, P W; Starinsky, N; Steinberg, P; Stenlund, E; Ster, A; Stoll, S P; Sugioka, M; Sugitate, T; Sullivan, J P; Sumi, Y; Sun, Z; Suzuki, M; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Taniguchi, E; Tannenbaum, M J; Thomas, J; Thomas, J H; Thomas, T L; Tian, W; Tojo, J; Torii, H; Towell, R S; Tserruya, I; Tsuruoka, H; Tsvetkov, A A; Tuli, S K; Tydesjö, H; Tyurin, N; Ushiroda, T; Van Hecke, H W; Velissaris, C; Velkovska, J; Velkovsky, M; Vinogradov, A A; Volkov, M A; Vorobyov, A; Vznuzdaev, E; Wang, H; Watanabe, Y; White, S N; Witzig, C; Wohn, F K; Woody, C L; Xie, W; Yagi, K; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, Z; Zhou, S; Zhou, S

    2002-08-26

    We present results on the measurement of Lambda and Lambda(macro) production in Au+Au collisions at square root of (S (NN) = 130 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider. The transverse momentum spectra were measured for minimum bias and for the 5% most central events. The Lambda;/Lambda ratios are constant as a function of p(T) and the number of participants. The measured net Lambda density is significantly larger than predicted by models based on hadronic strings (e.g., HIJING) but in approximate agreement with models which include the gluon-junction mechanism. PMID:12190391

  6. ΛΛ Correlation function in Au+Au collisions at √[S(NN)]=200  GeV.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Campbell, J M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kosarzewski, L K; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Page, B S; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Pile, P; Planinic, M; Pluta, J; Poljak, N; Poniatowska, K; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Simko, M; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2015-01-16

    We present ΛΛ correlation measurements in heavy-ion collisions for Au+Au collisions at sqrt[s_{NN}]=200  GeV using the STAR experiment at the Relativistic Heavy-Ion Collider. The Lednický-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the ΛΛ correlation function and interaction parameters for dihyperon searches are discussed. PMID:25635541

  7. Measurements of strange hadrons KS0, Λ and Ξ from Au+Au collisions at √SNN = 14.5 GeV in STAR

    NASA Astrophysics Data System (ADS)

    Usman Ashraf, Muhammad

    2016-01-01

    We report the measurements of the production of strange hadrons KS0, Λ and Ξ at mid rapidity in Au+Au collisions at √SNN = 14.5 GeV from the Beam Energy Scan (BES) program at the BNL Relativistic Heavy Ion Collider (RHIC). The collision energy dependence of strange hadron yields are also presented. To understand the recombination and part.on energy loss mechanisms, nuclear modification factors and baryon to meson ratios are measured and also compared with the statistical and thermal model.

  8. Pseudorapidity and Centrality Dependence of the Collective Flow of Charged Particles in Au+Au Collisions at (sNN)=130 GeV

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Henderson, C.; Hofman, D.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Steinberg, P.; Stephans, G. S.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    2002-11-01

    This paper describes the measurement of collective flow for charged particles in Au+Au collisions at (sNN)=130 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). The measured azimuthal hit anisotropy is presented over a wide range of pseudorapidity (-5.0<η<5.3) for the first time at this energy. The result, averaged over momenta and particle species, is observed to reach 7% for peripheral collisions at midrapidity, falling off with centrality and increasing |η|. These results call into question the common assumption of longitudinal boost invariance over a large region of rapidity in RHIC collisions.

  9. Centrality dependence of charged particle multiplicity at midrapidity in Au+Au collisions at (sNN)=130 GeV

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; Garcia, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Heintzelman, G. A.; Henderson, C.; Hołyński, R.; Hofman, D. J.; Holzman, B.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Lin, W. T.; Manly, S.; McLeod, D.; Michałowski, J.; Mignerey, A. C.; Mülmenstädt, J.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sarin, P.; Sawicki, P.; Skulski, W.; Steadman, S. G.; Stephans, G. S.; Steinberg, P.; Stodulski, M.; Sukhanov, A.; Tang, J.-L.; Teng, R.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Wadsworth, B.; Wolfs, F. L.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.

    2002-03-01

    We present a measurement of the pseudorapidity density of primary charged particles near midrapidity in Au+Au collisions at (sNN)=130 GeV as a function of the number of participating nucleons. The pseudorapidity density, dNch/dη\\|\\|η\\|<1/(1/2), rises from 2.87+/-0.21 in peripheral events (~83) to 3.45+/-0.18 in central events (~353), which is 53+/-8% higher than pp&; collisions at a similar center-of-mass energy. This is consistent with an additional contribution to charged particle production that scales with the number of binary nucleon-nucleon collisions (Ncoll).

  10. The role of interfaces in the magnetoresistance of Au/Fe/Au/Fe/GaAs(001)

    SciTech Connect

    Enders, A.; Monchesky, T. L.; Myrtle, K.; Urban, R.; Heinrich, B.; Kirschner, J.; Zhang, X.-G.; Butler, W. H.

    2001-06-01

    The electron transport and magnetoresistance (MR) were investigated in high quality crystalline epitaxial Fe(001) and Au(001) films and exchange coupled Au/Fe/Au/Fe/GaAs(001) trilayer structures. Fits to the experimental data were based on the semiclassical Boltzmann equation, which incorporates the electronic properties obtained from first-principles local density functional calculations. The fits require a surprisingly high asymmetry for the spin dependent electron lifetimes in Fe, {tau}{sup {down_arrow}}/{tau}{sup {up_arrow}}=10 at room temperature. Despite the large atomic terraces at the Au/vacuum and Fe/GaAs interfaces the scattering at the outer interfaces was found to be diffuse. The origin of MR in Au/Fe/Au/Fe/GaAs(001) structures is due to electron channeling in the Au spacer layer. The measured MR is consistent with the diffusivity parameters s{sup {up_arrow}}=0.55, s{sup {down_arrow}}=0.77 at the metal{endash}metal interfaces. {copyright} 2001 American Institute of Physics.

  11. Plasmonic Fano resonance and dip of Au-SiO2-Au nanomatryoshka.

    PubMed

    Liaw, Jiunn-Woei; Chen, Huang-Chih; Kuo, Mao-Kuen

    2013-01-01

    This study theoretically investigates Fano resonances and dips of an Au-SiO2-Au nanomatryoshka that is excited by a nearby electric dipole. An analytical solution of dyadic Green's functions is used to analyze the radiative and nonradiative power spectra of a radial dipole in the proximity of a nanomatryoshka. From these spectra, the plasmon modes and Fano resonances that accompany the Fano dips are identified. In addition, the scattering and absorption spectra of a nanomatryoshka that is illuminated by a plane wave are investigated to confirm these modes and Fano dips. Our results reveal that a Fano dip splits each of the dipole and quadrupole modes into bonding and anti-bonding modes. The Fano dip and resonance result from the destructive interference of the plasmon modes of the Au shell and the Au core. The Fano factors that are obtained from the nonradiative power spectra of the Au shell and the Au core of a nanomatryoshka are in accordance with those obtained from the absorption cross section spectra. Moreover, these Fano factors increase as the plasmonic coupling of the Au shell with the core increases for both dipole and quadrupole modes. PMID:24206789

  12. Plasmonic Fano resonance and dip of Au-SiO2-Au nanomatryoshka

    PubMed Central

    2013-01-01

    This study theoretically investigates Fano resonances and dips of an Au-SiO2-Au nanomatryoshka that is excited by a nearby electric dipole. An analytical solution of dyadic Green's functions is used to analyze the radiative and nonradiative power spectra of a radial dipole in the proximity of a nanomatryoshka. From these spectra, the plasmon modes and Fano resonances that accompany the Fano dips are identified. In addition, the scattering and absorption spectra of a nanomatryoshka that is illuminated by a plane wave are investigated to confirm these modes and Fano dips. Our results reveal that a Fano dip splits each of the dipole and quadrupole modes into bonding and anti-bonding modes. The Fano dip and resonance result from the destructive interference of the plasmon modes of the Au shell and the Au core. The Fano factors that are obtained from the nonradiative power spectra of the Au shell and the Au core of a nanomatryoshka are in accordance with those obtained from the absorption cross section spectra. Moreover, these Fano factors increase as the plasmonic coupling of the Au shell with the core increases for both dipole and quadrupole modes. PMID:24206789

  13. Centrality dependence of heavy flavor production from single electron measurement in √{S}=200 GeV Au +Au collisions

    NASA Astrophysics Data System (ADS)

    Bielcik, J.; STAR Collaboration

    2006-08-01

    We present preliminary measurements of electron production in p+p, d+Au, and Au+Au collisions at √{S}=200 GeV for transverse momenta 1.5 GeV/c

  14. Layered double hydroxide supported gold nanoclusters by glutathione-capped Au nanoclusters precursor method for highly efficient aerobic oxidation of alcohols

    NASA Astrophysics Data System (ADS)

    Li, Lun; Dou, Liguang; Zhang, Hui

    2014-03-01

    M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 +/- 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ~0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity or selectivity. The AuNCs/M(= Ni, Co)3Al-LDH catalysts present even higher alcohol oxidation activity than AuNCs/Mg3Al-LDH. Particularly, AuNCs/Ni3Al-LDH-0.22 exhibits the highest activity (46 500 h-1) for the aerobic oxidation of 1-phenylethanol under solvent-free conditions attributed to its strongest Au-support synergy. The excellent activity and stability of AuNCs/M3Al-LDH catalysts render these materials promising candidates for green base-free selective oxidation of alcohols by molecular oxygen.M3Al-layered double hydroxide (LDH, M = Mg, Ni, Co) supported Au nanoclusters (AuNCs) catalysts have been prepared for the first time by using water-soluble glutathione-capped Au nanoclusters as precursor. Detailed characterizations show that the ultrafine Au nanoclusters (ca. 1.5 +/- 0.6 nm) were well dispersed on the surface of LDH with a loading of Au below ~0.23 wt% upon synergetic interaction between AuNCs and M3Al-LDH. AuNCs/Mg3Al-LDH-0.23 exhibits much higher catalytic performance for the oxidation of 1-phenylethanol in toluene than Au/Mg3Al-LDH(DP) by the conventional deposition precipitation method and can be applied for a wide range of alcohols without basic additives. This catalyst can also be reused without loss of activity

  15. Fabrication of segmented Au/Co/Au nanowires: insights in the quality of Co/Au junctions.

    PubMed

    Jang, Bumjin; Pellicer, Eva; Guerrero, Miguel; Chen, Xiangzhong; Choi, Hongsoo; Nelson, Bradley J; Sort, Jordi; Pané, Salvador

    2014-08-27

    Electrodeposition is a versatile method, which enables the fabrication of a variety of wire-like nanoarchitectures such as nanowires, nanorods, and nanotubes. By means of template-assisted electrodeposition, segmented Au/Co/Au nanowires are grown in anodic aluminum oxide templates from two different electrolytes. To tailor the properties of the cobalt segments, several electrochemical conditions are studied as a function of current density, pulse deposition, and pH. The morphology, crystal structure, and magnetic properties are accordingly investigated. Changes in the deposition conditions affect the cobalt electrocrystallization process directly. Cobalt tends to crystallize mainly in the hexagonal close-packed structure, which is the reason cobalt might not accommodate satisfactorily on the face-centered cubic Au surface or vice versa. We demonstrate that by modifying the electrolyte and the applied current densities, changes in the texture and the crystalline structure of cobalt lead to a good quality connection between dissimilar segments. In particular, lowering the bath pH, or using pulse plating at a high overpotential, produces polycrystalline fcc Co and thus well-connected Co/Au bimetallic junctions with smooth interface. These are crucial factors to be carefully considered taking into account that nanowires are potential building blocks in micro- and nanoelectromechanical systems. PMID:25025496

  16. A comparative study of the Au + H{sub 2}, Au{sup +} + H{sub 2}, and Au{sup −} + H{sub 2} systems: Potential energy surfaces and dynamics of reactive collisions

    SciTech Connect

    Dorta-Urra, Anaís; Zanchet, Alexandre; Roncero, Octavio; Aguado, Alfredo

    2015-04-21

    In order to study the Au{sup −} + H{sub 2} collision, a new global potential energy surface (PES) describing the ground electronic state of AuH{sub 2}{sup −} system is developed and compared with the PESs of the neutral [Zanchet et al., J. Chem. Phys. 132, 034301 (2010)] and cationic systems [Anaís et al., J. Chem. Phys. 135, 091102 (2011)]. We found that Au{sup −} − H{sub 2} presents a H-Au-H insertion minimum attributed to the stabilization of the LUMO 3b{sub 2} orbital, which can be considered as the preamble of the chemisorption well appearing in larger gold clusters. While the LUMO orbital is stabilized, the HOMO 6a{sub 1} is destabilized, creating a barrier at the geometry where the energy orbitals’ curves are crossing. In the anion, this HOMO is doubly occupied, while in the neutral system is half-filled and completely empty in the cation, explaining the gradual disappearance of the well and the barrier as the number of electrons decreases. The cation presents a well in the entrance channel partially explained by electrostatic interactions. The three systems’ reactions are highly endothermic, by 1.66, 2.79, and 3.23 eV for AuH, AuH{sup +}, and AuH{sup −} products, respectively. The reaction dynamics is studied using quasi-classical trajectory method for the three systems. The one corresponding to the anionic system is new in this work. Collision energies between 1.00 and 8.00 eV, measured for the cation, are in good agreement with the simulated cross section for the AuH{sup +}. It was also found that the total fragmentation, in three atoms, competes becoming dominant at sufficiently high energy. Here, we study the competition between the two different reaction pathways for the anionic, cationic, and neutral species, explaining the differences using a simple model based on the topology of the potential energy surfaces.

  17. Evidence of final-state suppression of high-p{_ T} hadrons in Au + Au collisions using d + Au measurements at RHIC

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wysłouch, B.; Zhang, J.

    Transverse momentum spectra of charged hadrons with pT < 6 GeV/c have been measured near mid-rapidity (0.2 < ɛ < 1.4) by the PHOBOS experiment at RHIC in Au + Au and d + Au collisions at {√ {s{NN}} = {200 GeV}}. The spectra for different collision centralities are compared to {p + ¯ {p}} collisions at the same energy. The resulting nuclear modification factor for central Au + Au collisions shows evidence of strong suppression of charged hadrons in the high-pT region (>2 GeV/c). In contrast, the d + Au nuclear modification factor exhibits no suppression of the high-pT yields. These measurements suggest a large energy loss of the high-pT particles in the highly interacting medium created in the central Au + Au collisions. The lack of suppression in d + Au collisions suggests that it is unlikely that initial state effects can explain the suppression in the central Au + Au collisions. PACS: 25.75.-q

  18. Evolution in the charge injection efficiency of evaporated Au contacts on a molecularly doped polymer

    NASA Astrophysics Data System (ADS)

    Ioannidis, Andronique; Facci, John S.; Abkowitz, Martin A.

    1998-08-01

    Injection efficiency from evaporated Au contacts on a molecularly doped polymer (MDP) system has been previously observed to evolve from blocking to ohmic over time. In the present article this contact forming phenomenon is analyzed in detail. The initially blocking nature of the Au contact is in contrast with that expected from the relative workfunctions of Au and of the polymer which suggest Au should inject holes efficiently. It is also in apparent contrast to a differently prepared interface of the same materials. The phenomenon is not unique to this interface, having been confirmed also for evaporated Ag and mechanically made liquid Hg contacts on the same MDP. The MDP is a disordered solid state solution of electroactive triarylamine hole transporting TPD molecules in a polycarbonate matrix. The trap-free hole-transport MDP provides a model system for the study of metal/polymer interfaces by enabling the use of a recently developed technique that gives a quantitative measure of contact injection efficiency. The technique combines field-dependent steady state injection current measurements at a contact under test with time-of-flight (TOF) mobility measurements made on the same sample. In the present case, MDP films were prepared with two top vapor-deposited contacts, one of Au (test contact) and one of Al (for TOF), and a bottom carbon-loaded polymer electrode which is known to be ohmic for hole injection. The samples were aged at various temperatures below the glass transition of the MDP (85 °C) and the evolution of current versus field and capacitance versus frequency behaviors are followed in detail over time and analyzed. Control measurements ensure that the evolution of the electrical properties is due to the Au/polymer interface behavior and not the bulk. All evaporated Au contacts eventually achieved ohmic injection. The evaporated Au/MDP interface was also investigated by transmission electron microscopy as a function of time and showed no evidence of

  19. Iodide-induced organothiol desorption and photochemical reaction, gold nanoparticle (AuNP) fusion, and SERS signal reduction in organothiol-containing AuNP aggregates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gold nanoparticles (AuNPs) have been used extensively as surface-enhanced Raman spectroscopic (SERS) substrates for their large SERS enhancements and widely believed chemical stability. Presented is the finding that iodide can rapidly reduce the SERS intensity of the ligands, including organothiols ...

  20. Revisiting the S-Au(111) interaction: Static or Dynamic?

    SciTech Connect

    Biener, M M; Biener, J; Friend, C M

    2004-08-17

    The chemical inertness typically observed for Au does not imply a general inability to form stable bonds with non-metals but is rather a consequence of high reaction barriers. The Au-S interaction is probably the most intensively studied interaction of Au surfaces with non-metals as, for example, it plays an important role in Au ore formation, and controls the structure and dynamics of thiol-based self-assembled-monolayers (SAMs). In recent years a quite complex picture of the interaction of sulfur with Au(111) surfaces emerged, and a variety of S-induced surface structures was reported under different conditions. The majority of these structures were interpreted in terms of a static Au surface, where the positions of the Au atoms remain essentially unperturbed. Here we demonstrate that the Au(111) surface exhibits a very dynamic character upon interaction with adsorbed sulfur: low sulfur coverages modify the surface stress of the Au surface leading to lateral expansion of the surface layer; large-scale surface restructuring and incorporation of Au atoms into a growing two-dimensional AuS phase were observed with increasing sulfur coverage. These results provide new insight into the Au-S surface chemistry, and reveal the dynamic character of the Au(111) surface.

  1. Controlled deposition of Au on (BiO)2CO3 microspheres: the size and content of Au nanoparticles matter.

    PubMed

    Li, Qiuyan; Hao, Xiaodong; Guo, Xiaolong; Dong, Fan; Zhang, Yuxin

    2015-05-21

    Novel 3D Au/(BiO)2CO3 (Au/BOC) heterostructures with size-controlled Au nanoparticles (NPs) (2-10 nm) were first synthesized and used in photocatalytic removal of ppb-level NO for air cleaning. The photocatalytic performance of Au/BOC heterostructures was enhanced by fine-tuning the content of Au and the size of Au NPs. A new photocatalysis mechanism of surface scattering and reflecting (SSR) coupled with surface plasmon resonance (SPR) was proposed to understand the enhanced photocatalytic activity. PMID:25906416

  2. Site Preference of Ternary Alloying Additions to AuTi

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Mosca, Hugo O.; Noebe, Ronald D.

    2006-01-01

    Atomistic modeling of the site substitution behavior of several alloying additions, namely. Na, Mg, Al, Si. Sc, V, Cr, Mn. Fe, Co, Ni, Cu, Zn, Y, Zr. Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, and Pt in B2 TiAu is reported. The 30 elements can be grouped according to their absolute preference for a specific site, regardless of concentration, or preference for available sites in the deficient sublattice. Results of large scale simulations are also presented, distinguishing between additions that remain in solution from those that precipitate a second phase.

  3. Suppression of Upsilon production in d + Au and Au + Au collisions at root s(NN) = 200 GeV (vol 735, pg 127, 2014)

    SciTech Connect

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Gliske, S.; Krueger, K.; Spinka, H. M.; Underwood, D. G.

    2014-07-30

    We report measurements of Υ meson production in p + p, d +Au, and Au+Aucollisions using the STAR detector at RHIC. We compare the Υ yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d +Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p +p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Υ (1S + 2S + 3S) in the rapidity range |y| < 1 in d + Aucollisions of RdAu = 0.79 ± 0.24(stat.) ± 0.03(syst.) ± 0.10(p + p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au + Au collisions, we measure a nuclear modification factor of R AA = 0.49 ±0.1(stat.) ±0.02(syst.) ±0.06(p + p syst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state Υ mesons in Au + Aucollisions. The additional suppression in Au + Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark–Gluon Plasma. However, understanding the suppression seen in d + Au is still needed before any definitive statements about the nature of the suppression in Au + Au can be made.

  4. Tuning the SERS Response with Ag-Au Nanoparticle-Embedded Polymer Thin Film Substrates.

    PubMed

    Rao, V Kesava; Radhakrishnan, T P

    2015-06-17

    Development of facile routes to the fabrication of thin film substrates with tunable surface enhanced Raman scattering (SERS) efficiency and identification of the optimal conditions for maximizing the enhancement factor (EF) are significant in terms of both fundamental and application aspects of SERS. In the present work, polymer thin films with embedded bimetallic nanoparticles of Ag-Au are fabricated by a simple two-stage protocol. Ag nanoparticles are formed in the first stage, by the in situ reduction of silver nitrate by the poly(vinyl alcohol) (PVA) film through mild thermal annealing, without any additional reducing agent. In the second stage, aqueous solutions of chloroauric acid spread on the Ag-PVA thin film under ambient conditions, lead to the galvanic displacement of Ag by Au in situ inside the film, and the formation of Ag-Au particles. Evolution of the morphology of the bimetallic nanoparticles into hollow cage structures and the distribution of Au on the nanoparticles are revealed through electron microscopy and energy dispersive X-ray spectroscopy. The localized surface plasmon resonance (LSPR) extinction of the nanocomposite thin film evolves with the Ag-Au composition; theoretical simulation of the extinction spectra provides insight into the observed trends. The Ag-Au-PVA thin films are found to be efficient substrates for SERS. The EF follows the variation of the LSPR extinction vis-à-vis the excitation laser wavelength, but with an offset, and the maximum SERS effect is obtained at very low Au content; experiments with Rhodamine 6G showed EFs on the order of 10(8) and a limit of detection of 0.6 pmol. The present study describes a facile and simple fabrication of a nanocomposite thin film that can be conveniently deployed in SERS investigations, and the utility of the bimetallic system to tune and maximize the EF. PMID:26035249

  5. Fabrication of quantum dot/silica core-shell particles immobilizing Au nanoparticles and their dual imaging functions

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yoshio; Matsudo, Hiromu; Li, Ting-ting; Shibuya, Kyosuke; Kubota, Yohsuke; Oikawa, Takahiro; Nakagawa, Tomohiko; Gonda, Kohsuke

    2016-03-01

    The present work proposes preparation methods for quantum dot/silica (QD/SiO2) core-shell particles that immobilize Au nanoparticles (QD/SiO2/Au). A colloid solution of QD/SiO2 core-shell particles with an average size of 47.0 ± 6.1 nm was prepared by a sol-gel reaction of tetraethyl orthosilicate in the presence of the QDs with an average size of 10.3 ± 2.1 nm. A colloid solution of Au nanoparticles with an average size of 17.9 ± 1.3 nm was prepared by reducing Au3+ ions with sodium citrate in water at 80 °C. Introduction of amino groups to QD/SiO2 particle surfaces was performed using (3-aminopropyl)-triethoxysilane (QD/SiO2-NH2). The QD/SiO2/Au particles were fabricated by mixing the Au particle colloid solution and the QD/SiO2-NH2 particle colloid solution. Values of radiant efficiency and computed tomography for the QD/SiO2/Au particle colloid solution were 2.23 × 107 (p/s/cm2/sr)/(μW/cm2) at a QD concentration of 8 × 10-7 M and 1180 ± 314 Hounsfield units and an Au concentration of 5.4 × 10-2 M. The QD/SiO2/Au particle colloid solution was injected into a mouse chest wall. Fluorescence emitted from the colloid solution could be detected on the skin covering the chest wall. The colloid solution could also be X-ray-imaged in the chest wall. Consequently, the QD/SiO2/Au particle colloid solution was found to have dual functions, i.e., fluorescence emission and X-ray absorption in vivo, which makes the colloid solution suitable to function as a contrast agent for dual imaging processes.

  6. Characterization of Au and Bimetallic PtAu Nanoparticles on PDDA-Graphene Sheets as Electrocatalysts for Formic Acid Oxidation

    NASA Astrophysics Data System (ADS)

    Yung, Tung-Yuan; Liu, Ting-Yu; Huang, Li-Ying; Wang, Kuan-Syun; Tzou, Huei-Ming; Chen, Po-Tuan; Chao, Chi-Yang; Liu, Ling-Kang

    2015-09-01

    Nanocomposite materials of the Au nanoparticles (Au/PDDA-G) and the bimetallic PtAu nanoparticles on poly-(diallyldimethylammonium chloride) (PDDA)-modified graphene sheets (PtAu/PDDA-G) were prepared with hydrothermal method at 90 °C for 24 h. The composite materials Au/PDDA-G and PtAu/PDDA-G were evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) for exploring the structural characterization for the electrochemical catalysis. According to TEM results, the diameter of Au and bimetallic PtAu nanoparticles is about 20-50 and 5-10 nm, respectively. X-ray diffraction (XRD) results indicate that both of PtAu and Au nanoparticles exhibit the crystalline plane of (111), (200), (210), and (311). Furthermore, XRD data also show the 2°-3° difference between pristine graphene sheets and the PDDA-modified graphene sheets. For the catalytic activity tests of Au/PDDA-G and PtAu/PDDA-G, the mixture of 0.5 M aqueous H2SO4 and 0.5 M aqueous formic acid was used as model to evaluate the electrochemical characterizations. The catalytic activities of the novel bimetallic PtAu/graphene electrocatalyst would be anticipated to be superior to the previous electrocatalyst of the cubic Pt/graphene.

  7. Strangelet search in Au+Au collisions at sNN=200 GeV

    NASA Astrophysics Data System (ADS)

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Baumgart, S.; Belaga, V. V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Benedosso, F.; Betts, R. R.; Bhardwaj, S.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Blyth, S.-L.; Bombara, M.; Bonner, B. E.; Botje, M.; Bouchet, J.; Brandin, A. V.; Bravar, A.; Burton, T. P.; Bystersky, M.; Cadman, R. V.; Cai, X. Z.; Caines, H.; Sánchez, M. Calderón De La Barca; Callner, J.; Catu, O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, S. U.; Coffin, J. P.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; Moura, M. M. De; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; Didenko, L.; Dietel, T.; Djawotho, P.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, F.; Dunin, V. B.; Dunlop, J. C.; Mazumdar, M. R. Dutta; Eckardt, V.; Edwards, W. R.; Efimov, L. G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C. A.; Gaillard, L.; Ganti, M. S.; Garcia-Solis, E.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. G.; Gos, H.; Grebenyuk, O.; Grosnick, D.; Guertin, S. M.; Guimaraes, K. S. F. F.; Gupta, N.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; He, W.; Heinz, M.; Henry, T. W.; Hepplemann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D.; Hollis, R.; Horner, M. J.; Huang, H. Z.; Hughes, E. W.; Humanic, T. J.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jia, F.; Jones, P. G.; Judd, E. G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V. Yu.; Kim, B. C.; Kiryluk, J.; Kisiel, A.; Kislov, E. M.; Klein, S. R.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kouchpil, V.; Kowalik, K. L.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Kuhn, C.; Kulikov, A. I.; Kumar, A.; Kurnadi, P.; Kuznetsov, A. A.; Lamont, M. A. C.; Landgraf, J. M.; Lange, S.; Lapointe, S.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Lehocka, S.; Levine, M. J.; Li, C.; Li, Q.; Li, Y.; Lin, G.; Lin, X.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ludlam, T.; Lynn, D.; Ma, G. L.; Ma, J. G.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Martin, L.; Matis, H. S.; Matulenko, Yu. A.; McClain, C. J.; McShane, T. S.; Melnick, Yu.; Meschanin, A.; Millane, J.; Miller, M. L.; Minaev, N. G.; Mioduszewski, S.; Mironov, C.; Mischke, A.; Mitchell, J.; Mohanty, B.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Nepali, N. S.; Netrakanti, P. K.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okorokov, V.; Oldenburg, M.; Olson, D.; Pachr, M.; Pal, S. K.; Panebratsev, Y.; Pavlinov, A. I.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Planinic, M.; Pluta, J.; Poljak, N.; Porile, N.; Poskanzer, A. M.; Potekhin, M.; Potrebenikova, E.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Putschke, J.; Qattan, I. A.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Relyea, D.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Sahoo, R.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sarsour, M.; Sazhin, P. S.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shen, W. Q.; Shimanskiy, S. S.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Smirnov, N.; Snellings, R.; Sorensen, P.; Sowinski, J.; Speltz, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, T. D. S.; Staszak, D.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Z.; Surrow, B.; Symons, T. J. M.; Toledo, A. Szanto De; Szeliga, B.; Takahashi, J.; Tang, A. H.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Timoshenko, S.; Tokarev, M.; Trainor, T. A.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; Buren, G. Van; Kolk, N. Van Der; Leeuwen, M. Van; Molen, A. M. Vander; Varma, R.; Vasilevski, I. M.; Vasiliev, A. N.; Vernet, R.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Waggoner, W. T.; Wang, F.; Wang, G.; Wang, J. S.; Wang, X. L.; Wang, Y.; Watson, J. W.; Webb, J. C.; Westfall, G. D.; Wetzler, A.; , C. Whitten, Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, J.; Wu, Y.; Xu, N.; Xu, Q. H.; Xu, Z.; Yepes, P.; Yoo, I.-K.; Yue, Q.; Yurevich, V. I.; Zhan, W.; Zhang, H.; Zhang, W. M.; Zhang, Y.; Zhang, Z. P.; Zhao, Y.; Zhong, C.; Zhou, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zubarev, A. N.; Zuo, J. X.

    2007-07-01

    We have searched for strangelets in a triggered sample of 61 million central (top 4%) Au+Au collisions at sNN=200 GeV near beam rapidities at the STAR solenoidal tracker detector at the BNL Relativistic Heavy Ion Collider. We have sensitivity to metastable strangelets with lifetimes of order ⩾0.1 ns, in contrast to limits over ten times longer in BNL Alternating Gradient Synchrotron (AGS) studies and longer still at the CERN Super Proton Synchrotron (SPS). Upper limits of a few 10-6 to 10-7 per central Au+Au collision are set for strangelets with mass ≳30 GeV/c2.

  8. Catalytic Oxidation of Propylene, Toluene, Carbon Monoxide, and Carbon Black over Au/CeO2 Solids: Comparing the Impregnation and the Deposition-Precipitation Methods

    PubMed Central

    Aboukaïs, Antoine; El-Ayadi, Houda; Skaf, Mira; Labaki, Madona; Cousin, Renaud; Abi-Aad, Edmond

    2013-01-01

    Au/CeO2 solids were prepared by two methods: deposition-precipitation (DP) and impregnation (Imp). The prepared solids were calcined under air at 400°C. Both types of catalysts have been tested in the total oxidation of propylene, toluene, carbon monoxide, and carbon black. Au/CeO2-DP solids were the most reactive owing to the high number of gold nanoparticles and Au+ species and the low concentration of Cl− ions present on its surface compared to those observed in Au/CeO2-Imp solids. PMID:24198730

  9. No Keplerian Disk >10 AU Around the Protostar B335: Magnetic Braking or Young Age?

    NASA Astrophysics Data System (ADS)

    Yen, Hsi-Wei; Takakuwa, Shigehisa; Koch, Patrick M.; Aso, Yusuke; Koyamatsu, Shin; Krasnopolsky, Ruben; Ohashi, Nagayoshi

    2015-10-01

    We have conducted Atacama Large Millimeter/Submillimeter Array (ALMA) cycle 2 observations in the 1.3 mm continuum and in the C18O (2-1) and SO (56-45) lines at a resolution of ˜0.″3 toward the Class 0 protostar B335. The 1.3 mm continuum, C18O, and SO emission all show central compact components with sizes of ˜40-180 AU within more extended components. The C18O component shows signs of infalling and rotational motion. By fitting simple kinematic models to the C18O data, the protostellar mass is estimated to be 0.05 {M}⊙ . The specific angular momentum, on a 100 AU scale, is (4.3 ± 0.5) × 10-5 km s-1 pc. A similar specific angular momentum, (3-5) × 10-5 km s-1 pc, is measured on a 10 AU scale from the velocity gradient observed in the central SO component, and there is no clear sign of an infalling motion in the SO emission. By comparing the infalling and rotational motion, our ALMA results suggest that the observed rotational motion has not yet reached Keplerian velocity neither on a 100 AU nor even on a 10 AU scale. Consequently, the radius of the Keplerian disk in B335 (if present) is expected to be 1-3 AU. The expected disk radius in B335 is one to two orders of magnitude smaller than those of observed Keplerian disks around other Class 0 protostars. Based on the observed infalling and rotational motion from 0.1 pc to inner 100 AU scales, there are two possible scenarios to explain the presence of such a small Keplerian disk in B335: magnetic braking and young age. If our finding is the consequence of magnetic braking, ˜50% of the angular momentum of the infalling material within a 1000 AU scale might have been removed, and the magnetic field strength on a 1000 AU scale is estimated to be ˜200 μG. If it is young age, the infalling radius in B335 is estimated to be ˜2700 AU, corresponding to a collapsing timescale of ˜5 × 104 years.

  10. Directed Flow of Charged Kaons in Au+Au Collisions from the BES Program at RHIC

    NASA Astrophysics Data System (ADS)

    Pandit, Yadav; STAR Collaboration

    2015-08-01

    We report the measurement of the directed flow (v1) for charged kaons in Au+Au collisions at =7.7, 11.5, 19.6, 27, 39, 62.4 and 200 GeV as a function of rapidity and compare these results for pions, protons and antiprotons. These new kaon results may help to constrain the medium properties and collision dynamics including the in-medium kaon potential and baryon number transport in these collisions.

  11. Photoinduced drug release from thermosensitive AuNPs-liposome using a AuNPs-switch.

    PubMed

    An, Xueqin; Zhang, Fan; Zhu, Yinyan; Shen, Weiguo

    2010-10-14

    A thermosensitive liposome with embedded AuNPs in a bilayer was prepared using supercritical CO(2). The AuNPs-liposome can absorb a certain wavelength light, convert optical energy into heat, induce phase transition, and release drug. The results show that drug release from the liposome is due to the photothermic effects inducing phase transition of the liposome rather than destruction of the liposome structure. PMID:20820547

  12. Enhanced Second Harmonic Generation in AU/AI2O3/AU absorber

    NASA Astrophysics Data System (ADS)

    Huang, Fenglun; Bai, Songang; Li, Qiang; Qu, Yurui; Min, Qiu

    2016-01-01

    A kind of metal-insulator-metal (MIM) metamaterial absorber for generating second harmonic signal is investigated. The absorbers exhibit high absorption efficiency at the dip and notably enhance the generated second harmonic signal by a factor of over 30, in contrast to an Au/alumina double-layer without Au disk on the top. This study demonstrates the potential of metamaterial absorber for nonlinear photonics.

  13. Luminescent, bimetallic AuAg alloy quantum clusters in protein templates

    NASA Astrophysics Data System (ADS)

    Mohanty, Jyoti Sarita; Xavier, P. Lourdu; Chaudhari, Kamalesh; Bootharaju, M. S.; Goswami, N.; Pal, S. K.; Pradeep, T.

    2012-06-01

    We report the synthesis of luminescent AuAg alloy quantum clusters (QCs) in bovine serum albumin (BSA), for the first time, with experimentally determined atomic composition. Mixing of the as-synthesized protein-protected Au and Ag clusters resulted in the formation of alloy AuAg clusters within the BSA. Mass spectrometric analysis of the product of a 1 : 1 molar ratio reaction mixture of AuQC@BSA and AgQC@BSA suggested that the alloy clusters could be Au38-xAgx@BSA. Further analyses by standard techniques revealed that the alloy cluster core of ~1.2 nm diameter is composed of nearly zero valent Au and Ag atoms that exhibit distinctly different steady state and time resolved excited state luminescence profiles compared to the parent clusters. Tuning of the alloy composition was achieved by varying the molar ratio of the parent species in the reaction mixture and compositional changes were observed by mass spectrometry. In another approach, mixing of Au3+ ions with the as-synthesized AgQC@BSA also resulted in the formation of alloy clusters through galvanic exchange reactions. We believe that alloy clusters with the combined properties of the constituents in versatile protein templates would have potential applications in the future. The work presents interesting aspects of the reactivity of the protein-protected clusters.We report the synthesis of luminescent AuAg alloy quantum clusters (QCs) in bovine serum albumin (BSA), for the first time, with experimentally determined atomic composition. Mixing of the as-synthesized protein-protected Au and Ag clusters resulted in the formation of alloy AuAg clusters within the BSA. Mass spectrometric analysis of the product of a 1 : 1 molar ratio reaction mixture of AuQC@BSA and AgQC@BSA suggested that the alloy clusters could be Au38-xAgx@BSA. Further analyses by standard techniques revealed that the alloy cluster core of ~1.2 nm diameter is composed of nearly zero valent Au and Ag atoms that exhibit distinctly different

  14. Supramolecular functionalization and concomitant enhancement in properties of Au(25) clusters.

    PubMed

    Mathew, Ammu; Natarajan, Ganapati; Lehtovaara, Lauri; Häkkinen, Hannu; Kumar, Ravva Mahesh; Subramanian, Venkatesan; Jaleel, Abdul; Pradeep, Thalappil

    2014-01-28

    We present a versatile approach for tuning the surface functionality of an atomically precise 25 atom gold cluster using specific host-guest interactions between β-cyclodextrin (CD) and the ligand anchored on the cluster. The supramolecular interaction between the Au25 cluster protected by 4-(t-butyl)benzyl mercaptan, labeled Au25SBB18, and CD yielding Au25SBB18∩CDn (n = 1, 2, 3, and 4) has been probed experimentally using various spectroscopic techniques and was further analyzed by density functional theory calculations and molecular modeling. The viability of our method in modifying the properties of differently functionalized Au25 clusters is demonstrated. Besides modifying their optoelectronic properties, the CD moieties present on the cluster surface provide enhanced stability and optical responses which are crucial in view of the potential applications of these systems. Here, the CD molecules act as an umbrella which protects the fragile cluster core from the direct interaction with many destabilizing agents such as metal ions, ligands, and so on. Apart from the inherent biocompatibility of the CD-protected Au clusters, additional capabilities acquired by the supramolecular functionalization make such modified clusters preferred materials for applications, including those in biology. PMID:24313537

  15. Elliptic flow in Au+Au collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Vale, Carla M.; PHOBOS Collaboration; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Heintzelman, G. A.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Holynski, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Katzy, J.; Khan, N.; Kucewicz, W.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; McLeod, D.; Mignerey, A. C.; Ngyuen, M.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Reuter, M.; Roland, C.; Roland, G.; Rosenberg, L.; Sagerer, J.; Sarin, P.; Sawicki, P.; Skulski, W.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tang, J.-L.; Tonjes, M. B.; Trzupek, A.; van Nieuwenhuizen, G. J.; Verdier, R.; Veres, G.; Wolfs, F. L. H.; Wosiek, B.; Wozniak, K.; Wuosmaa, A. H.; Wyslouch, B.

    2005-04-01

    Elliptic flow is an interesting probe of the dynamical evolution of the dense system formed in the ultrarelativistic heavy ion collisions at the relativistic heavy ion collider (RHIC). The elliptic flow dependences on transverse momentum, centrality and pseudorapidity were measured using data collected by the PHOBOS detector, which offers a unique opportunity to study the azimuthal anisotropies of charged particles over a wide range of pseudorapidity. These measurements are presented, together with an overview of the analysis methods and a discussion of the results.

  16. Fabrication of High Sensitive Immunochromato Kit Using Au Colloid

    NASA Astrophysics Data System (ADS)

    Okamoto, Koji

    Au colloid have characteristics of surface plasmon resonance with absorption at 500 nm~600 nm wavelength. Surface on the citric acid Au colloid can be conjugated with protein eg. antibody. Various particle size of Au colloid makes it high sensitive immunochromato as diagnostics. High sensitive immunochromato will be useful for application of cancer marker eg. prostate specific antigen and influenza early diagnosis.

  17. Bonding, Luminescence, Metallophilicity in Linear Au3 and Au2Ag Chains Stabilized by Rigid Diphosphanyl NHC Ligands.

    PubMed

    Ai, Pengfei; Mauro, Matteo; Gourlaouen, Christophe; Carrara, Serena; De Cola, Luisa; Tobon, Yeny; Giovanella, Umberto; Botta, Chiara; Danopoulos, Andreas A; Braunstein, Pierre

    2016-09-01

    The heterofunctional and rigid ligand N,N'-diphosphanyl-imidazol-2-ylidene (PCNHCP; P = P(t-Bu)2), through its phosphorus and two N-heterocyclic carbene (NHC) donors, stabilizes trinuclear chain complexes, with either Au3 or AgAu2 cores, and dinuclear Au2 complexes. The two oppositely situated PCNHCP (L) ligands that "sandwich" the metal chain can support linear and rigid structures, as found in the known tricationic Au(I) complex [Au3(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 (OTf = CF3SO3; [Au3L2](OTf)3; Chem. Commun. 2014, 50, 103-105) now also obtained by transmetalation from [Ag3(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 ([Ag3L2](OTf)3), or in the mixed-metal tricationic [Au2Ag(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 ([Au2AgL2](OTf)3). The latter was obtained stepwise by the addition of AgOTf to the digold(I) complex [Au2(μ2-PCNHCP,κP,κCNHC)2](OTf)2 ([Au2L2](OTf)2). The latter contains two dangling P donors and displays fluxional behavior in solution, and the Au···Au separation of 2.8320(6) Å in the solid state is consistent with metallophilic interactions. In the solvento complex [Au3Cl2(tht)(μ3-PCNHCP,κP,κCNHC,κP)](OTf)·MeCN ([Au3Cl2(tht)L](OTf)·MeCN), which contains only one L and one tht ligand (tht = tetrahydrothiophene), the metal chain is bent (148.94(2)°), and the longer Au···Au separation (2.9710(4) Å) is in line with relaxation of the rigidity due to a more "open" structure. Similar features were observed in [Au3Cl2(SMe2)L](OTf)·2MeCN. A detailed study of the emission properties of [Au3L2](OTf)3, [Au3Cl2(tht)L](OTf)·MeCN, [Au2L2](OTf)2, and [Au2AgL2](OTf)3 was performed by means of steady state and time-resolved photophysical techniques. The complex [Au3L2](OTf)3 displays a bright (photoluminescence quantum yield = 80%) and narrow emission band centered at 446 nm with a relatively small Stokes' shift and long-lived excited-state lifetime on the microsecond timescale, both in solution and in the solid state. In line with the very narrow emission

  18. Experimental and Theoretical Studies on Oxidation of Cu-Au Alloy Surfaces: Effect of Bulk Au Concentration

    PubMed Central

    Okada, Michio; Tsuda, Yasutaka; Oka, Kohei; Kojima, Kazuki; Diño, Wilson Agerico; Yoshigoe, Akitaka; Kasai, Hideaki

    2016-01-01

    We report results of our experimental and theoretical studies on the oxidation of Cu-Au alloy surfaces, viz., Cu3Au(111), CuAu(111), and Au3Cu(111), using hyperthermal O2 molecular beam (HOMB). We observed strong Au segregation to the top layer of the corresponding clean (111) surfaces. This forms a protective layer that hinders further oxidation into the bulk. The higher the concentration of Au in the protective layer formed, the higher the protective efficacy. As a result, of the three Cu-Au surfaces studied, Au3Cu(111) is the most stable against dissociative adsorption of O2, even with HOMB. We also found that this protective property breaks down for oxidations occurring at temperatures above 300 K. PMID:27516137

  19. Identified particle distributions in pp and Au+Au collisions atsqrt sNN=200 GeV

    SciTech Connect

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M; Arkhipkin, D.; Averichev, G.S.; Badyal,S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele,S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj,S.; Bhaskar, P.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar,A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez,M.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Ganti, M.S.; Gutierrez, T.D.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Cronstal, S.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris,J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang,S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.S.; Kopytine,S.M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger,K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; et al.

    2003-10-06

    Transverse mass and rapidity distributions for charged pions, charged kaons, protons and antiprotons are reported for {radical}sNN = 200 GeV pp and Au+Au collisions at RHIC. The transverse mass distributions are rapidity independent within |y| < 0.5, consistent with a boost-invariant system in this rapidity interval. Spectral shapes and relative particle yields are similar in pp and peripheral Au+Au collisions and change smoothly to central Au+Au collisions. No centrality dependence was observed in the kaon and antiproton production rates relative to the pion production rate from medium-central to central collisions. Chemical and kinetic equilibrium model fits to our data reveal strong radial flow and relatively long duration from chemical to kinetic freeze-out in central Au+Au collisions. The chemical freeze-out temperature appears to be independent of initial conditions at RHIC energies.

  20. Experimental and Theoretical Studies on Oxidation of Cu-Au Alloy Surfaces: Effect of Bulk Au Concentration.

    PubMed

    Okada, Michio; Tsuda, Yasutaka; Oka, Kohei; Kojima, Kazuki; Diño, Wilson Agerico; Yoshigoe, Akitaka; Kasai, Hideaki

    2016-01-01

    We report results of our experimental and theoretical studies on the oxidation of Cu-Au alloy surfaces, viz., Cu3Au(111), CuAu(111), and Au3Cu(111), using hyperthermal O2 molecular beam (HOMB). We observed strong Au segregation to the top layer of the corresponding clean (111) surfaces. This forms a protective layer that hinders further oxidation into the bulk. The higher the concentration of Au in the protective layer formed, the higher the protective efficacy. As a result, of the three Cu-Au surfaces studied, Au3Cu(111) is the most stable against dissociative adsorption of O2, even with HOMB. We also found that this protective property breaks down for oxidations occurring at temperatures above 300 K. PMID:27516137

  1. The effect of Au amount on size uniformity of self-assembled Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, S.-H.; Wang, D.-C.; Chen, G.-Y.; Chen, K.-Y.

    2008-03-01

    The self-assembled fabrication of nanostructure, a dreaming approach in the area of fabrication engineering, is the ultimate goal of this research. A finding was proved through previous research that the size of the self-assembled gold nanoparticles could be controlled with the mole ratio between AuCl4- and thiol. In this study, the moles of Au were fixed, only the moles of thiol were adjusted. Five different mole ratios of Au/S with their effect on size uniformity were investigated. The mole ratios were 1:1/16, 1:1/8, 1:1, 1:8, 1:16, respectively. The size distributions of the gold nanoparticles were analyzed by Mac-View analysis software. HR-TEM was used to derive images of self-assembled gold nanoparticles. The result reached was also the higher the mole ratio between AuCl4- and thiol the bigger the self-assembled gold nanoparticles. Under the condition of moles of Au fixed, the most homogeneous nanoparticles in size distribution derived with the mole ratio of 1:1/8 between AuCl4- and thiol. The obtained nanoparticles could be used, for example, in uniform surface nanofabrication, leading to the fabrication of ordered array of quantum dots.

  2. From the Ternary Eu(Au/In)2 and EuAu4(Au/In)2 with Remarkable Au/In Distributions to a New Structure Type: The Gold-Rich Eu5Au16(Au/In)6 Structure.

    PubMed

    Steinberg, Simon; Card, Nathan; Mudring, Anja-Verena

    2015-09-01

    The ternary Eu(Au/In)2 (EuAu(0.46)In(1.54(2))) (I), EuAu4(Au/In)2 (EuAu(4+x)In(2-x) with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au(17.29)In(4.71(3))) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squared Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au(17.29)In(4.71(3))) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2-"EuAu4In2". The site preferences of the disordered Au/In positions in II were investigated for different hypothetical "EuAu4(Au/In)2" models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au-In contacts. A chemical bonding analysis on two "EuAu5In" and "EuAu4In2" models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems. PMID:26270622

  3. Human erythrocytes and neuroblastoma cells are affected in vitro by Au(III) ions

    SciTech Connect

    Suwalsky, Mario; Gonzalez, Raquel; Villena, Fernando; Aguilar, Luis F.; Sotomayor, Carlos P.; Bolognin, Silvia; Zatta, Paolo

    2010-06-25

    Gold compounds are well known for their neurological and nephrotoxic implications. However, haematological toxicity is one of the most serious toxic and less studied effects. The lack of information on these aspects of Au(III) prompted us to study the structural effects induced on cell membranes, particularly that of human erythrocytes. AuCl{sub 3} was incubated with intact erythrocytes, isolated unsealed human erythrocyte membranes (IUM) and molecular models of the erythrocyte membrane. The latter consisted of multibilayers of dimyristoylphosphatidylcholine and dimyristoylphosphatidylethanolamine, phospholipids classes located in the outer and inner monolayers of the human erythrocyte membrane, respectively. This report presents evidence that Au(III) interacts with red cell membranes as follows: (a) in scanning electron microscopy studies on human erythrocytes it was observed that Au(III) induced shape changes at a concentration as low as 0.01 {mu}M; (b) in isolated unsealed human erythrocyte membranes Au(III) induced a decrease in the molecular dynamics and/or water content at the glycerol backbone level of the lipid bilayer polar groups in a 5-50 {mu}M concentration range, and (c) X-ray diffraction studies showed that Au(III) in the 10 {mu}m-1 mM range induced increasing structural perturbation only to dimyristoylphosphatidylcholine bilayers. Additional experiments were performed in human neuroblastoma cells SH-SY5Y. A statistically significant decrease of cell viability was observed with Au(III) ranging from 0.1 {mu}M to 100 {mu}M.

  4. Tailoring the Electronic and Catalytic Properties of Au25 Nanoclusters via Ligand Engineering.

    PubMed

    Li, Gao; Abroshan, Hadi; Liu, Chong; Zhuo, Shuo; Li, Zhimin; Xie, Yan; Kim, Hyung J; Rosi, Nathaniel L; Jin, Rongchao

    2016-08-23

    To explore the electronic and catalytic properties of nanoclusters, here we report an aromatic-thiolate-protected gold nanocluster, [Au25(SNap)18](-) [TOA](+), where SNap = 1-naphthalenethiolate and TOA = tetraoctylammonium. It exhibits distinct differences in electronic and catalytic properties in comparison with the previously reported [Au25(SCH2CH2Ph)18](-), albeit their skeletons (i.e., Au25S18 framework) are similar. A red shift by ∼10 nm in the HOMO-LUMO electronic absorption peak wavelength is observed for the aromatic-thiolate-protected nanocluster, which is attributed to its dilated Au13 kernel. The unsupported [Au25(SNap)18](-) nanoclusters show high thermal and antioxidation stabilities (e.g., at 80 °C in the present of O2, excess H2O2, or TBHP) due to the effects of aromatic ligands on stabilization of the nanocluster's frontier orbitals (HOMO and LUMO). Furthermore, the catalytic activity of the supported Au25(SR)18/CeO2 (R = Nap, Ph, CH2CH2Ph, and n-C6H13) is examined in the Ullmann heterocoupling reaction between 4-methyl-iodobenzene and 4-nitro-iodobenzene. Results show that the activity and selectivity of the catalysts are largely influenced by the chemical nature of the protecting thiolate ligands. This study highlights that the aromatic ligands not only lead to a higher conversion in catalytic reaction but also markedly increase the yield of the heterocoupling product (4-methyl-4'-nitro-1,1'-biphenyl). Through a combined approach of experiment and theory, this study sheds light on the structure-activity relationships of the Au25 nanoclusters and also offers guidelines for tailoring nanocluster properties by ligand engineering for specific applications. PMID:27442235

  5. Spectra and elliptic flow for Λ, Ξ, and Ω in 200 A GeV Au+Au collisions

    NASA Astrophysics Data System (ADS)

    Zhu, Xiangrong; Song, Huichao

    2016-01-01

    Using VISHNU hybrid model, we calculate the pT-spectra and elliptic flow of Λ, Ξ, and Ω in 200 A GeV Au+Au collisions. Comparisons with the STAR measurements show that the model generally describes these soft hadron data. We also briefly study and discuss the mass ordering of elliptic flow among π, K, p, Λ, Ξ, and Ω in minimum bias Au+Au collisions.

  6. Directed Flow of Identified Particles in Au+Au Collisions at S-NN=200 GeV at RHIC

    SciTech Connect

    Adamczyk L.; Agakishiev,G.; Aggarwal, M.M.; Ahammed,Z. et al.

    2012-05-15

    STAR's measurements of directed flow (v{sub 1}) around midrapidity for {pi}{sup {+-}}, K{sup {+-}}, K{sub S}{sup 0}, p, and {bar p} in Au+Au collisions at {radical}s{sub NN} = 200 GeV are presented. A negative v{sub 1}(y) slope is observed for most of produced particles ({pi}{sup {+-}}, K{sup {+-}}, K{sub S}{sup 0}, and {bar p}). In 5%-30% central collisions, a sizable difference is present between the v{sub 1}(y) slope of protons and antiprotons, with the former being consistent with zero within errors. The v{sub 1} excitation function is presented. Comparisons to model calculations (RQMD, UrQMD, AMPT, QGSM with parton recombination, and a hydrodynamics model with a tilted source) are made. For those models which have calculations of v{sub 1} for both pions and protons, none of them can describe v{sub 1}(y) for pions and protons simultaneously. The hydrodynamics model with a tilted source as currently implemented cannot explain the centrality dependence of the difference between the v{sub 1}(y) slopes of protons and antiprotons.

  7. AU-FREDI - AUTONOMOUS FREQUENCY DOMAIN IDENTIFICATION

    NASA Technical Reports Server (NTRS)

    Yam, Y.

    1994-01-01

    The Autonomous Frequency Domain Identification program, AU-FREDI, is a system of methods, algorithms and software that was developed for the identification of structural dynamic parameters and system transfer function characterization for control of large space platforms and flexible spacecraft. It was validated in the CALTECH/Jet Propulsion Laboratory's Large Spacecraft Control Laboratory. Due to the unique characteristics of this laboratory environment, and the environment-specific nature of many of the software's routines, AU-FREDI should be considered to be a collection of routines which can be modified and reassembled to suit system identification and control experiments on large flexible structures. The AU-FREDI software was originally designed to command plant excitation and handle subsequent input/output data transfer, and to conduct system identification based on the I/O data. Key features of the AU-FREDI methodology are as follows: 1. AU-FREDI has on-line digital filter design to support on-orbit optimal input design and data composition. 2. Data composition of experimental data in overlapping frequency bands overcomes finite actuator power constraints. 3. Recursive least squares sine-dwell estimation accurately handles digitized sinusoids and low frequency modes. 4. The system also includes automated estimation of model order using a product moment matrix. 5. A sample-data transfer function parametrization supports digital control design. 6. Minimum variance estimation is assured with a curve fitting algorithm with iterative reweighting. 7. Robust root solvers accurately factorize high order polynomials to determine frequency and damping estimates. 8. Output error characterization of model additive uncertainty supports robustness analysis. The research objectives associated with AU-FREDI were particularly useful in focusing the identification methodology for realistic on-orbit testing conditions. Rather than estimating the entire structure, as is

  8. Three views of two giant streams: Aligned observations at 1 AU, 4.6 AU, and 5.9 AU

    NASA Technical Reports Server (NTRS)

    Siscoe, George; Intriligator, Devrie

    1993-01-01

    A close radial alignment of the Interplanetary Monitoring Platform (IMP) and Pioneers 10 and 11 spacecraft in 1974 allows a nearly unambiguous, empirical study of the radial evolution of the interaction regions of two contrasting weak and strong, giant streams. The study confirms the main aspects of the standard model of corotating interaction regions: an expanding and strengthening pair of forward-reverse shocks sandwich a stream interface. It adds the follwoing concepts: stream group speed--the speed at the stream interface tends to remain constant with distance; corotating stream complexes--interaction regions can include features like noncompressive density enhancements and streamer belts; secondary interfaces--a possible precursor to the reverse shock; and emerging stream interfaces--one emerged between 1 AU and 4.6 AU. The study uses the conservation specific entropy to correlate features between spacecraft.

  9. Photoreduction of Au(III) to form Au(0) nanoparticles using ferritin as a photocatalyst

    NASA Astrophysics Data System (ADS)

    Hilton, Robert J.; Keyes, Jeremiah D.; Watt, Richard K.

    2010-04-01

    Gold metal nanoparticles have applications in bio sensing technology, nano-tube formation, and cancer therapy. We report attempts to synthesize gold nanoparticles within the ferritin cavity (8 nm) or to use ferritin as a scaffold for coating gold on the outside surface (12 nm). The intrinsic iron oxide core of ferritin is a semi-conductor and light can excite electrons to a conduction band producing a powerful reductant when a sacrificial electron donor fills the electron hole. We present a method using ferritin to photo chemically reduce Au(III) to metallic gold nanoparticles. During initial studies we observed that the choice of buffers influenced the products that formed as evidenced by a red product formed in TRIS and a purple produce formed in MOPS. Gold nanoparticles formed in MOPS buffer in the absence of illumination have diameters of 15-30 nm whereas illumination in TRIS buffer produced 5-10 nm gold nanoparticles. Increases in temperature cause the gold nanoparticles to form more rapidly. Chemical reduction and photochemical reduction methods have very different reaction profiles with photochemical reduction possessing a lag phase prior to the formation of gold nanoparticles.

  10. M-Au/TiO2 (M = Ag, Pd, and Pt) nanophotocatalyst for overall solar water splitting: role of interfaces.

    PubMed

    Melvin, Ambrose A; Illath, Kavya; Das, Tanmay; Raja, Thirumalaiswamy; Bhattacharyya, Somnath; Gopinath, Chinnakonda S

    2015-08-28

    M-Au/TiO2 (M = Ag, Pd, Pt) composites were prepared through a facile one-pot photodeposition synthesis and evaluated for solar water splitting (SWS) with and without a sacrificial agent. The M-Au combination exhibits a dominant role in augmenting the H2 generation activity by forming a bi-metallic system. Degussa P25 was used as a TiO2 substrate to photodeposit Au followed by Au + M (M = Ag/Pd/Pt). The SWS activity of the M-Au/TiO2 was determined through photocatalytic H2 production in the presence of methanol as a sacrificial agent under one sun conditions with an AM1.5 filter. The highest H2 yield was observed for Pt0.5-Au1/TiO2 and was around 1.3 ± 0.07 mmol h(-1) g(-1), with an apparent quantum yield (AQY) of 6.4%. Pt0.5-Au1/TiO2 also demonstrated the same activity for 25 cycles of five hours each for 125 h. Critically, the same Pt0.5-Au1/TiO2 catalyst was active in overall SWS (OSWS) without any sacrificial agent, with an AQY = 0.8%. The amount of Au and/or Pt was varied to obtain the optimum composition and it was found that the Pt0.5-Au1/TiO2 composition exhibits the best activity. Detailed characterization by physico-chemical, spectral and microscopy measurements was carried out to obtain an in-depth understanding of the origin of the photocatalytic activity of Pt0.5-Au1/TiO2. These in-depth studies show that gold interacts predominantly with oxygen vacancies present on titania surfaces, and Pt preferentially interacts with gold for an effective electron-hole pair separation at Pt-Au interfaces and electron storage in metal particles. The Pt in Pt0.5-Au1/TiO2 is electronically and catalytically different from the Pt in Pt/TiO2 and it is predicted that the former suppresses the oxygen reduction reaction. PMID:26199221

  11. Measurement of flux-weighted average cross sections for 197Au(γ, xn) reactions and isomeric yield ratios of 196m,gAu with bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Naik, Haladhara; Kim, Guinyun; Kim, Kwangsoo; Zaman, Muhammad; Goswami, Ashok; Lee, Man Woo; Yang, Sung-Chul; Lee, Young-Ouk; Shin, Sung-Gyun; Cho, Moo-Hyun

    2016-04-01

    Photo-neutron cross sections of 197Au were experimentally determined for the bremsstrahlung end-point energies of 50, 60, and 70 MeV, by utilizing activation and off-line γ-ray spectrometric technique, using the 100 MeV electron linac at the Pohang Accelerator Laboratory (PAL), Pohang, Korea. The 197Au(γ, xn; x = 1- 6) reaction cross sections were calculated as a function of the bombarding photon energy by using the TALYS 1.6 computer code with default parameters. The flux-weighted average cross sections were obtained from the literature data and the theoretical values of TALYS 1.6 and TENDL-2014, for mono-energetic photons, and are found to be in good agreement with the present data. Isomeric yield ratios of 196m2,gAu from the 197Au(γ, n) reaction were also determined for the bremsstrahlung end-point energies of 50, 60, and 70 MeV, from the reaction cross sections of m2- and g-states, based on the present experimental data, and are found to be in good agreement with the theoretical values based on TALYS 1.6 and TENDL-2014.

  12. J/ Φ photo-production measurement at RHIC using the STAR detector for √sNN = 200 GeV Au +Au collisions

    NASA Astrophysics Data System (ADS)

    de Silva, Chanaka

    2014-09-01

    Ultra-peripheral collision events are effectively photo-production on nuclear targets. Relativistic heavy ions carry strong transverse electromagnetic fields that can be treated as sources of quasi-real virtual photons. The ions interact through photon-Pomeron and photon-photon collisions at impact parameters more than twice the nuclear radius, so hadronic interactions are suppressed in ultra-peripheral events. These events also provide an ideal proving ground for new programs in e +A physics. We present the latest results on J/ Φ photo-production using √sNN = 200 GeV Au +Au collisions in the STAR experiment at RHIC. The pT distribution of the J/ Φ mesons peaks at very low pT, consistent with expectations for coherent photo-production. We further discuss the current status of measurements that are expected to provide information on nuclear gluon distributions, gluon shadowing, generalized parton distributions and parton form factors. Finally, we present the measurement of the ratio of J/ Φ to ρ production as a function of rapidity for √sNN = 200 GeV Au +Au collisions. Possible theory comparisons are also discussed.

  13. Centrality dependence of charged hadron and strange hadron elliptic flow from sNN=200 GeV Au+Au collisions

    NASA Astrophysics Data System (ADS)

    Abelev, B. I.; Aggarwal, M. M.; Ahammed, Z.; Anderson, B. D.; Arkhipkin, D.; Averichev, G. S.; Bai, Y.; Balewski, J.; Barannikova, O.; Barnby, L. S.; Baudot, J.; Baumgart, S.; Beavis, D. R.; Bellwied, R.; Benedosso, F.; Betts, R. R.; Bhardwaj, S.; Bhasin, A.; Bhati, A. K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bombara, M.; Bonner, B. E.; Botje, M.; Braidot, E.; Brandin, A. V.; Bueltmann, S.; Burton, T. P.; Bystersky, M.; Cai, X. Z.; Caines, H.; de La Barca Sánchez, M. Calderón; Callner, J.; Catu, O.; Cebra, D.; Cervantes, M. C.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, J. Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K. E.; Christie, W.; Chung, S. U.; Clarke, R. F.; Codrington, M. J. M.; Coffin, J. P.; Cormier, T. M.; Cosentino, M. R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Daugherity, M.; de Moura, M. M.; Dedovich, T. G.; Dephillips, M.; Derevschikov, A. A.; Souza, R. Derradi De; Didenko, L.; Dietel, T.; Djawotho, P.; Dogra, S. M.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, F.; Dunlop, J. C.; Mazumdar, M. R. Dutta; Edwards, W. R.; Efimov, L. G.; Elhalhuli, E.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Feng, A.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gaillard, L.; Ganti, M. S.; Garcia-Solis, E.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y. N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Grube, B.; Guertin, S. M.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hallman, T. J.; Hamed, A.; Harris, J. W.; He, W.; Heinz, M.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hoffman, A. M.; Hoffmann, G. W.; Hofman, D. J.; Hollis, R. S.; Huang, H. Z.; Hughes, E. W.; Humanic, T. J.; Igo, G.; Iordanova, A.; Jacobs, P.; Jacobs, W. W.; Jakl, P.; Jin, F.; Jones, P. G.; Judd, E. G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Kettler, D.; Khodyrev, V. Yu.; Kiryluk, J.; Kisiel, A.; Klein, S. R.; Knospe, A. G.; Kocoloski, A.; Koetke, D. D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kouchpil, V.; Kravtsov, P.; Kravtsov, V. I.; Krueger, K.; Kuhn, C.; Kumar, A.; Kumar, L.; Kurnadi, P.; Lamont, M. A. C.; Landgraf, J. M.; Lange, S.; Lapointe, S.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, C.-H.; Levine, M. J.; Li, C.; Li, Y.; Lin, G.; Lin, X.; Lindenbaum, S. J.; Lisa, M. A.; Liu, F.; Liu, H.; Liu, J.; Liu, L.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Love, W. A.; Lu, Y.; Ludlam, T.; Lynn, D.; Ma, G. L.; Ma, J. G.; Ma, Y. G.; Mahapatra, D. P.; Majka, R.; Mangotra, L. K.; Manweiler, R.; Margetis, S.; Markert, C.; Matis, H. S.; Matulenko, Yu. A.; McShane, T. S.; Meschanin, A.; Millane, J.; Miller, M. L.; Minaev, N. G.; Mioduszewski, S.; Mischke, A.; Mitchell, J.; Mohanty, B.; Morozov, D. A.; Munhoz, M. G.; Nandi, B. K.; Nattrass, C.; Nayak, T. K.; Nelson, J. M.; Nepali, C.; Netrakanti, P. K.; Ng, M. J.; Nogach, L. V.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Okada, H.; Okorokov, V.; Oldenburg, M.; Olson, D.; Pachr, M.; Pal, S. K.; Panebratsev, Y.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S. C.; Planinic, M.; Pluta, J.; Poljak, N.; Porile, N.; Poskanzer, A. M.; Potekhin, M.; Potukuchi, B. V. K. S.; Prindle, D.; Pruneau, C.; Pruthi, N. K.; Putschke, J.; Qattan, I. A.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Relyea, D.; Ridiger, A.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Rose, A.; Roy, C.; Ruan, L.; Russcher, M. J.; Rykov, V.; Sahoo, R.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sarsour, M.; Schambach, J.; Scharenberg, R. P.; Schmitz, N.; Schweda, K.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shabetai, A.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S. S.; Shi, X.-H.; Sichtermann, E. P.; Simon, F.; Singaraju, R. N.; Skoby, M. J.; Smirnov, N.; Snellings, R.; Sorensen, P.; Sowinski, J.; Spinka, H. M.; Srivastava, B.; Stadnik, A.; Stanislaus, T. D. S.; Staszak, D.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Subba, N. L.; Sumbera, M.; Sun, X. M.; Sun, Z.; Surrow, B.; Symons, T. J. M.; Toledo, A. Szanto De; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thein, D.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Timoshenko, S.; Tokarev, M.; Tram, V. N.; Trattner, A. L.; Trentalange, S.; Tribble, R. E.; Tsai, O. D.; Ulery, J.; Ullrich, T.; Underwood, D. G.; Buren, G. Van; Kolk, N. Van Der; Leeuwen, M. Van; Molen, A. M. Vander; Varma, R.; Vasconcelos, G. M. S.; Vasilevski, I. M.; Vasiliev, A. N.; Videbaek, F.; Vigdor, S. E.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Wada, M.; Waggoner, W. T.; Wang, F.; Wang, G.; Wang, J. S.; Wang, Q.; Wang, X.; Wang, X. L.; Wang, Y.; Webb, J. C.; Westfall, G. D.; , C. Whitten, Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, J.; Wu, Y.; Xu, N.; Xu, Q. H.; Xu, Z.; Yepes, P.; Yoo, I.-K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, H.; Zhang, S.; Zhang, W. M.; Zhang, Y.; Zhang, Z. P.; Zhao, Y.; Zhong, C.; Zhou, J.; Zoulkarneev, R.; Zoulkarneeva, Y.; Zuo, J. X.

    2008-05-01

    We present STAR results on the elliptic flow v2 of charged hadrons, strange and multistrange particles from sNN=200 GeV Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC). The detailed study of the centrality dependence of v2 over a broad transverse momentum range is presented. Comparisons of different analysis methods are made in order to estimate systematic uncertainties. To discuss the nonflow effect, we have performed the first analysis of v2 with the Lee-Yang zero method for KS0 and Λ. In the relatively low pT region, pT⩽2GeV/c, a scaling with mT-m is observed for identified hadrons in each centrality bin studied. However, we do not observe v2(pT) scaled by the participant eccentricity to be independent of centrality. At higher pT,2⩽pT⩽6GeV/c,v2 scales with quark number for all hadrons studied. For the multistrange hadron Ω, which does not suffer appreciable hadronic interactions, the values of v2 are consistent with both mT-m scaling at low pT and number-of-quark scaling at intermediate pT. As a function of collision centrality, an increase of pT-integrated v2 scaled by the participant eccentricity has been observed, indicating a stronger collective flow in more central Au+Au collisions.

  14. Composite particle production in relativistic Au+Au collisions at AGS: First results from the E866 forward spectrometer @ 2, 4, and 10.8 A{center_dot}GeV

    SciTech Connect

    Ashktorab, K.

    1996-12-31

    Particle spectra were measured for Au + Au collisions at 2, 4, and 10. 8 A{center_dot}GeV using the E866 spectrometers. Recent results on proton emission and composite particle production form the E866 forward spectrometer data taken in 1994 together with the first results from the 1995/6 AGS running period are presented. Preliminary results indicate a decrease in the coalescence scaling coefficient with increasing projectile energy and centrality.

  15. Low-Lying Electronic States of CuAu.

    PubMed

    Alizadeh Sanati, Davood; Andrae, Dirk

    2016-07-28

    Coinage metal diatomic molecules are building blocks for nanostructured materials, electronic devices, and catalytically or photochemically active systems that are currently receiving lively interest in both fundamental and applied research. The theoretical study presented here elucidates the electronic structure in the ground and several low-lying excited states of the diatomic molecule CuAu that result from the combination of the atoms in their ground states nd(10)(n + 1)s(1 2)S and lowest excited d-hole states nd(9)(n + 1)s(2 2)D (n = 3 for Cu, n = 5 for Au). Full and smooth potential energy curves, obtained at the multireference configuration interaction (MRCI) level of theory, are presented for the complete set of the thus resulting 44 Λ-S terms and 86 Ω terms. Our approach is based on a scalar relativistic description using the Douglas-Kroll-Hess (DKH) Hamiltonian, with subsequent perturbative inclusion of spin-orbit (SO) coupling via the spin-orbit terms of the Breit-Pauli (BP) Hamiltonian. The Ω terms span an energy interval of about 7 eV at the ground state's equilibrium distance. Spectroscopic constants, calculated for all terms, are shown to accurately reproduce the observation for those nine terms that are experimentally known. PMID:27379475

  16. Zinc (hydr)oxide/graphite oxide/AuNPs composites: role of surface features in H₂S reactive adsorption.

    PubMed

    Giannakoudakis, Dimitrios A; Bandosz, Teresa J

    2014-12-15

    Zinc hydroxide/graphite oxide/AuNPs composites with various levels of complexity were synthesized using an in situ precipitation method. Then they were used as H2S adsorbents in visible light. The materials' surfaces were characterized before and after H2S adsorption by various physical and chemical methods (XRD, FTIR, thermal analysis, potentiometric titration, adsorption of nitrogen and SEM/EDX). Significant differences in surface features and synergistic effects were found depending on the materials' composition. Addition of graphite oxide and the deposition of gold nanoparticles resulted in a marked increase in the adsorption capacity in comparison with that on the zinc hydroxide and zinc hydroxide/AuNP. Addition of AuNPs to zinc hydroxide led to a crystalline ZnO/AuNP composite while the zinc hydroxide/graphite oxide/AuNP composite was amorphous. The ZnOH/GO/AuNPs composite exhibited the greatest H2S adsorption capacity due to the increased number of OH terminal groups and the conductive properties of GO that facilitated the electron transfer and consequently the formation of superoxide ions promoting oxidation of hydrogen sulfide. AuNPs present in the composite increased the conductivity, helped with electron transfer to oxygen, and prevented the fast recombination of the electrons and holes. PMID:25306297

  17. In situ biosynthesis of Ag, Au and bimetallic nanoparticles using Piper pedicellatum C.DC: green chemistry approach.

    PubMed

    Tamuly, Chandan; Hazarika, Moushumi; Borah, Sarat Ch; Das, Manash R; Boruah, Manas P

    2013-02-01

    The synthesis of Ag, Au and Ag-Au bimetallic nanoparticles using Piper pedicellatum C.DC leaf extract is demonstrated here. The rapid formation of stable Ag and Au nanoparticles has been found using P. pedicellatum C.DC leaf extract in aqueous medium at normal atmospheric condition. Competitive reduction of Ag(+) and Au(3+) ions present simultaneously in solution during exposure to P. pedicellatum C.DC leaf extract leads to the synthesis of bimetallic Ag-Au nanoparticles in solution. Transmission electron microscopy (TEM) analysis revealed that the Ag nanoparticles predominantly form spherical in shape with the size range of 2.0±0.5-30.0±1.2 nm. In case of Au nanoparticles, the particles are spherical in shape along with few triangular, hexagonal and pentagonal shaped nanoparticles also observed. X-ray diffraction (XRD) studies revealed that the nanoparticles were face centered cubic (fcc) in shape. Fourier transform infrared spectroscopy (FTIR) showed nanoparticles were capped with plant compounds. The chemical constituents, viz. catechin, gallic acid, courmaric acid and protocatechuic acid of the leaf extract were identified which may act as a reducing, stabilizing and capping agent. The expected reaction mechanism in the formation of Ag and Au nanoparticles is also reported. PMID:23107941

  18. Neutral pion production in \\sqrt{s_{NN}}=200 GeV Cu+Au collisions at PHENIX

    NASA Astrophysics Data System (ADS)

    Campbell, Sarah; PHENIX Collaboration

    2015-05-01

    Cu+Au collisions at RHIC generate asymmetric initial geometries and densities in both azimuth and rapidity. High pT π0s produced in \\sqrt{sNN} = 200 GeV Cu+Au collisions provide new environments to study parton energy loss in the Quark Gluon Plasma, including very central events where the Cu nucleus is enveloped by the Au nucleus. By measuring π0 yields in ϕ relative to the event plane, we can probe different core-corona regions in these very central events and study the path length dependence of energy loss in various lopsided initial geometries. PHENIX has observed the suppression of π0s as a function of the azimuthal angle with respect to the event plane in \\sqrt{sNN} = 200 GeV Au+Au collisions and found it consistent with a larger than quadratic path length dependence suggesting a non-perturbative energy loss model applies. The unique collision geometries available in Cu+Au provide new settings to explore and possibly confirm this path length dependence. The status of the Cu+Au π0 analysis is presented.

  19. Facile preparation of novel core-shell enzyme-Au-polydopamine-Fe₃O₄ magnetic bionanoparticles for glucosesensor.

    PubMed

    Peng, Hua-Ping; Liang, Ru-Ping; Zhang, Li; Qiu, Jian-Ding

    2013-04-15

    In this study, a novel biomolecule immobilization approach has been proposed to the synthesis of multi-functional core-shell glucose oxidase-Au-polydopamine-Fe₃O₄ magnetic bionanoparticles (GOx-Au-PDA-Fe₃O₄ MBNPs) using the one-pot chemical polymerization method. Then, a high performance biosensor has been constructed by effectively attaching the proposed GOx-Au-PDA-Fe₃O₄ MBNPs to the surface of the magnetic glassy carbon electrode. Scanning electron microscope, energy dispersive x-ray spectrometer, UV-vis spectroscopy, and electrochemical methods were used to characterize the GOx-Au-PDA-Fe₃O₄ MBNPs. The resultant GOx-Au-PDA-Fe₃O₄ MBNPs not only have the magnetism of Fe₃O₄ nanoparticles which makes them easily manipulated by an external magnetic field, but also have the excellent biocompatibility of PDA to maintain the native structure of the GOx, and good conductivity of Au nanoparticles which can facilitate the direct electrochemistry of GOx in the biofilm. Hence, the present GOx-Au-PDA-Fe₃O₄ biofilm displays good linear amperometric response to glucose concentration ranging from 0.02 to 1.875 mM. This efficient biomolecule immobilization platform is recommended for the preparation of many other MBNPs with interesting properties and application potentials in many fields, such as biosensing, biocatalysis, biofuel cells, and bioaffinity separation. PMID:23208101

  20. Releasing of Sputtered Au Film by Dissolving Sacrificial Layer and Its Self-Standing on Perforated Substrate

    NASA Astrophysics Data System (ADS)

    Miyamoto, Yu; Fujii, Yuma; Yamano, Masafumi; Harigai, Toru; Suda, Yoshiyuki; Takikawa, Hirofumi; Nishiuchi, Mamiko; Sakaki, Hironao; Kondo, Kiminori

    2015-09-01

    Free-standing thin films such as diamond-like carbon (DLC) and gold (Au) have been attracted increasing interests as film targets used in the laser-driven ion acceleration experiment. One of the methods to make the free-standing thin film is to use a soluble sacrifice layer. In this study, the fabrication technique of self-standing Au thin film is presented. Gelatin, oblate, silk fibroin, and NaCl were examined as a. Au thin films were deposited by DC plasma sputtering on sacrifice layers. The gelatin and oblate were used as the sacrificial layer and the supporting substrate. Silk fibroin was coated on glass substrates by a spin coater. The NaCl sacrificial layers were deposited on flat Si substrates by the vacuum vapor deposition system. Sputtered Au thin films were released by immersing the substrates in purified water. Self-standing Au thin films were fabricated by scooping up the released Au thin film on a perforated substrate. The highest quality of the self-standing Au thin film was achieved by using NaCl sacrificial layer. This work was supported by JSPS KAKENHI Grant-in-Aid for Scientific Research and Toukai Foundation for Technology.

  1. Magnetic and thermodynamic properties of GdCu4Au

    NASA Astrophysics Data System (ADS)

    Bashir, Aiman K.; Tchoula Tchokonté, Moise B.; Britz, Douglas; Sondezi, B. M.; Strydom, André M.

    2015-03-01

    The results of magnetic susceptibility, χ(T), magnetization, σ(μ0H), and specific heat, CP(T), for GdCu4Au are presented. The room temperature powder X-ray diffraction studies indicate a cubic MgCu4Sn - type crystal structure with space group Fbar 43m (No.216). The low field dc χ(T) data shows an antiferromagnetic - like (AFM) anomaly associated with a Néel temperature TN = 10.8 K for GdCu4Au. In the paramagnetic region above TN, χ(T) data follows the Curies - Weiss law with an effective magnetic moment μeff = 7.444(1) μB and paramagnetic Weiss temperature θP = -15.01(2) K. The experimental value of is close to the calculated value of 7.94 μB expected for the free Gd3+-ion. The field-cooled (FC) and zero-field-cooled (ZFC) χ(T) data provide evidence for the formation of spin-glass state with a freezing temperature Tf = 15 K. σ(μ0H) measured in the ordering region (below TN) shows that GdCu4Au undergoes metamagnetic transition above 0.7 T, characterized by a slight upward curvature above this field. Measurement of σ(μ0H) in the paramagnetic regions show a linear behaviour up to 0.7 T and a downward curvature at high fields. CP(T) data shows an AFM - like phase transition at TN = 10.4 K close to the phase transition observed in χ(T) results. The 4f-electron entropy reaches the value of Rln2 close to TN at 9.02 K and reaches the value of Rln(2J + 1) at T = 180 K.

  2. From the ternary Eu(Au/In)2 and EuAu4(Au/In)2 with remarkable Au/In distributions to a new structure type: The gold-rich Eu5Au16(Au/In)6 structure

    DOE PAGESBeta

    Steinberg, Simon; Card, Nathan; Mudring, Anja -Verena

    2015-08-13

    The ternary Eu(Au/In)2 (EuAu0.46In1.54(2)) (I), EuAu4(Au/In)2 (EuAu4+xIn2–x with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squaredmore » Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2–“EuAu4In2”. The site preferences of the disordered Au/In positions in II were investigated for different hypothetical “EuAu4(Au/In)2” models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au–In contacts. Furthermore, a chemical bonding analysis on two “EuAu5In” and “EuAu4In2” models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.« less

  3. Enhanced spin pumping at yttrium iron garnet/Au interfaces

    SciTech Connect

    Burrowes, C.; Heinrich, B.; Kardasz, B.; Montoya, E. A.; Girt, E.; Sun Yiyan; Song, Young-Yeal; Wu Mingzhong

    2012-02-27

    Spin injection across the ferrimagnetic insulator yttrium iron garnet (YIG)/normal metal Au interface was studied using ferromagnetic resonance. The spin mixing conductance was determined by comparing the Gilbert damping parameter {alpha} in YIG/Au and YIG/Au/Fe heterostructures. The main purpose of this study was to correlate the spin pumping efficiency with chemical modifications of the YIG film surface using in situ etching and deposition techniques. By means of Ar{sup +} ion beam etching, one is able to increase the spin mixing conductance at the YIG/Au interface by a factor of 5 compared to the untreated YIG/Au interface.

  4. Thermal Desorption of Au from W(001) Surface

    NASA Astrophysics Data System (ADS)

    Błaszczyszyn, R.; Chrzanowski, J.; Godowski, P. J.

    2000-12-01

    Adsorption of Au on W(001) at 450 K up to multilayer structures was investigated. Temperature programmed desorption technique was used in determination of coverage dependent desorption energy (region up to one monolayer). Results were discussed in terms of competitive interactions of Au--Au and Au--W atoms. Simple procedure for prediction of faceting behavior on the interface, basing on the desorption data, was postulated. It was deduced that the Au/W(001) interface should not show faceting tendency after thermal treatment.

  5. First results on d+Au collisions from PHOBOS

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Noell, A.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sawicki, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Teng, R.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wadsworth, B.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.; Zhang, J.

    2004-02-01

    We have measured transverse momentum distributions of charged hadrons produced in d+Au collisions at √SNN = 200 GeV, in the range 0.25 < pT < 6.0 GeV/c. With increasing collision centrality, the yield at high transverse momenta increases more rapidly than the overall particle density, leading to a strong modification of the spectral shape. This change in spectral shape is qualitatively different from observations in Au+Au collisions at the same energy. The results provide important information for discriminating between different models for the suppression of high-pT hadrons observed in Au+Au collisions.

  6. Surface effects on the radiation response of nanoporous Au foams

    SciTech Connect

    Fu, E. G.; Caro, M.; Wang, Y. Q.; Baldwin, K.; Caro, A.; Zepeda-Ruiz, L. A.; Bringa, E.; Nastasi, M.

    2012-11-05

    We report on an experimental and simulation campaign aimed at exploring the radiation response of nanoporous Au (np-Au) foams. We find different defect accumulation behavior by varying radiation dose-rate in ion-irradiated np-Au foams. Stacking fault tetrahedra are formed when np-Au foams are irradiated at high dose-rate, but they do not seem to be formed in np-Au at low dose-rate irradiation. A model is proposed to explain the dose-rate dependent defect accumulation based on these results.

  7. Synthesis, structure, and bonding in K12Au21Sn4. A polar intermetallic compound with dense Au20 and open AuSn4 layers

    SciTech Connect

    Li, Bin; Kim, Sung-Jin; Miller, Gordon J.; and Corbett, John D.

    2009-10-29

    The new phase K{sub 12}Au{sub 21}Sn{sub 4} has been synthesized by direct reaction of the elements at elevated temperatures. Single crystal X-ray diffraction established its orthorhombic structure, space group Pmmn (No. 59), a = 12.162(2); b = 18.058(4); c = 8.657(2) {angstrom}, V = 1901.3(7) {angstrom}{sup 3}, and Z = 2. The structure consists of infinite puckered sheets of vertex-sharing gold tetrahedra (Au{sub 20}) that are tied together by thin layers of alternating four-bonded-Sn and -Au atoms (AuSn{sub 4}). Remarkably, the dense but electron-poorer blocks of Au tetrahedra coexist with more open and saturated Au-Sn layers, which are fragments of a zinc blende type structure that maximize tetrahedral heteroatomic bonding outside of the network of gold tetrahedra. LMTO band structure calculations reveal metallic properties and a pseudogap at 256 valence electrons per formula unit, only three electrons fewer than in the title compound and at a point at which strong Au-Sn bonding is optimized. Additionally, the tight coordination of the Au framework atoms by K plays an important bonding role: each Au tetrahedra has 10 K neighbors and each K atom has 8-12 Au contacts. The appreciably different role of the p element Sn in this structure from that in the triel members in K{sub 3}Au{sub 5}In and Rb{sub 2}Au{sub 3}Tl appears to arise from its higher electron count which leads to better p-bonding (valence electron concentrations = 1.32 versus 1.22).

  8. Synthesis of gold nanoparticles by laser ablation of an Au foil inside and outside ionic liquids

    NASA Astrophysics Data System (ADS)

    Wender, Heberton; Andreazza, Marcos L.; Correia, Ricardo R. B.; Teixeira, Sérgio R.; Dupont, Jairton

    2011-03-01

    Stable gold nanoparticles (AuNPs) were prepared by simple laser ablation of an Au foil placed inside or outside four ionic liquids (ILs), without the addition of any external chemical reagent. Irregular spherical AuNPs with a diameter range of 5 to 20 nm were produced after laser ablation of an Au foil located inside or outside the ILs 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF4), 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMI.PF6) and 1-(3-cyanopropyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ((BCN)MI.NTf2). Additionally, whereas laser ablation inside the IL 1-n-butyl-3-methylimidazolium dicyanamide BMI.N(CN)2 produced flower-like shaped nanoparticles of about 50 nm in size, ablation outside this IL presented similar results to the others ILs studied, as determined by TEM and UV-Vis. The size and shape of the prepared NPs were related to where NP nucleation and growth occurred, i.e., at the IL surface or within the IL. Indeed, the chemical composition of the IL/air interface and surface ion orientation played important roles in the stabilization of the AuNPs formed by laser ablation outside the ILs.

  9. Optical properties of ZnSe doped with Ag and Au

    NASA Astrophysics Data System (ADS)

    Dean, P. J.; Fitzpatrick, B. J.; Bhargava, R. N.

    1982-08-01

    We present bound-exciton (BE) and donor-acceptor-pair (DAP) spectra of ZnSe grown by liquid-phase epitaxy and doped with the transition metals (TM) Ag and Au. Luminescence, luminescence excitation, and time decay spectra establish the assignments of the spectral features and show that Ag forms a medium deep acceptor, (EA)Ag=431+/-2 meV, consistent with the activation energy for thermal quenching of the DAP spectra. This thermal technique, together with the less precise spectral measurements available for the more-strongly-phonon-coupled Au acceptor indicate that (EA)Au~550 meV, appreciably less than the probable value for Cu, ~650 meV. Peculiarities in the BE properties within this TM sequence are discussed with reference to the influence of their d-state characteristics. Strong BE luminescence with no-phonon energy near 2.747 eV is attributed to a neutral AgZn-AgI associate, possibly a split interstitial. Reasons for its absence in ZnSe: Au are discussed. Isotope effects in this spectrum and that of the Li neutral acceptor BE are contrasted. The latter provides proof that LiZn is the persistent shallow Td site acceptor in ZnSe. Further associate BE luminescence is tentatively identified for ZnSe: Ag and ZnSe: Au.

  10. Third-order optical nonlinearity studies of bilayer Au/Ag metallic films

    NASA Astrophysics Data System (ADS)

    Mezher, M. H.; Chong, W. Y.; Zakaria, R.

    2016-05-01

    This paper presents nonlinear optical studies of bilayer metallic films of gold (Au) and silver (Ag) on glass substrate prepared using electron beam evaporation. The preparation of Au and Ag nanoparticles (NPs) on the substrate involved the use of electron beam deposition, then thermal annealing at 600 °C and 270 °C, respectively, to produce a randomly distributed layer of Au and a layer of Ag NPs. Observation of field-effect scanning electron microscope images indicated the size of the NPs. Details of the optical properties related to peak absorption of surface plasmon resonance of the nanoparticle were revealed by use of UV-Vis spectroscopy. The Z-scan technique was used to measure the nonlinear absorption and nonlinear refraction of the fabricated NP layers. The third-order nonlinear refractive index coefficients for Au and Ag are (-9.34 and  -1.61)  ×  10-11 cm2 W-1 given lower n 2, in comparison with bilayer (Au and Ag) NPs at  -1.24  ×  10-10 cm2 W-1. The results show bilayer NPs have higher refractive index coefficients thus enhance the nonlinearity effects.

  11. A comparative investigation of the behaviors of H in Au and Ag from first principles

    NASA Astrophysics Data System (ADS)

    Han, Quan-Fu; Zhou, Zhen-Yu; Ma, Yuming; Liu, Yue-Lin

    2016-05-01

    Hydrogen (H) is a common impurity in metals and has a significant effect on their purification, even at concentrations of only a few parts per million. Here we present a comparative analysis of the behaviors of H in Au and Ag based on first-principles calculations. In bulk Au and Ag, the results demonstrate that the tetrahedral position is energetically more stable for a single H atom than the octahedral site. The concentration of H dissolving in the interstitial sites as a function of temperature is calculated in both metals. To characterize the dynamic behaviors, in bulk Au and Ag we determine the theoretical diffusivity and permeation of H, which are in quantitative agreement with the experimental data. Further, we investigate the role of vacancy on the formation of the H n -vacancy (H n V) via a clustering reaction. One vacancy can accommodate up to 9 H atoms in Au and capture as many as 7 H atoms in Ag. The H2 molecule in the vacancy is energetically unstable in both metals. These research results will provide a very useful reference for the refinement of Ag/Au as noble metals in industry.

  12. Au dotted magnetic network nanostructure and its application for on-site monitoring femtomolar level pesticide.

    PubMed

    Yang, Tianxi; Guo, Xiaoyu; Wang, Hui; Fu, Shuyue; Yu, Jie; Wen, Ying; Yang, Haifeng

    2014-04-01

    A novel magnetically responsive and surface-enhanced Raman spectroscopy (SERS) active nanocomposite is designed and prepared by direct grafting of Au nanoparticles onto the surface of magnetic network nanostructure (MNN) with the help of a nontoxic and environmentally friendly reagent of inositol hexakisphosphate shortly named as IP6. The presence of IP6 as a stabilizer and a bridging agent could weave Fe3O4 nanoparticles (NPs) into magnetic network nanostructure, which is easily dotted with Au nanoparticles (Au NPs). It has been shown firstly that the huge Raman enhancement of Au-MNN is reached by an external magnetic collection. Au-MNN presenting the large surface and high detection sensitivity enables it to exhibit multifunctional applications involving sufficient adsorption of dissolved chemical species for enrichment, separation, as well as a Raman amplifier for the analysis of trace pesticide residues at femtomolar level by a portable Raman spectrometer. Therefore, such multifunctional nanocomposites can be developed as a smart and promising nanosystem that integrates SERS approach with an easy assay for concentration by an external magnet for the effective on-site assessments of agricultural and environmental safety. PMID:24130070

  13. Exciton Formation and Quenching in a Au/CdS Core/Shell Nanostructure.

    PubMed

    Ziemannn, Dirk; May, Volkhard

    2015-10-15

    An atomistic description is presented of the excited state dynamics in spherical Au/CdS core/shell nanocrystals up to a diameter of 15 nm. Au-core excited states are considered in a multipole plasmon scheme, whereas a tight-binding description combined with a configuration interaction approach is used to compute single electron-hole pair excitations in the CdS-shell. The electron-hole pair energy-shift and screening due to an Au-core polarization is found of minor importance. For the studied system, the energy transfer coupling can be identified as the essential core-shell interaction. Characterizing the CdS-shell excitons by atomic centered transition charges and the Au-core by its multipole plasmon moments, an energy transfer coupling can be introduced that gives a complete microscopic description beyond any dipole-dipole approximation and with values around 10 meV. Together with a considerable plasmon-exciton energy mismatch, these coupling values explain the measured 300 ps lifetime of shell excitons due to energy transfer to the Au-core. PMID:26722776

  14. Tribological and microstructural comparison of HIPped PM212 and PM212/Au self-lubricating composites

    NASA Technical Reports Server (NTRS)

    Bogdanski, Michael S.; Sliney, Harold E.; Dellacorte, Christopher

    1992-01-01

    The feasibility of replacing the silver with the volumetric equivalent of gold in the chromium carbide-based self-lubricating composite PM212 (70 wt. percent NiCo-Cr3C2, 15 percent BaF2/CaF2 eutectic) was studied. The new composite, PM212/Au has the following composition: 62 wt. percent NiCo-Cr3C2, 25 percent Au, 13 percent BaF2/CaF2 eutectic. The silver was replaced with gold to minimize the potential reactivity of the composite with possible environmental contaminants such as sulfur. The composites were fabricated by hot isostatic pressing (HIPping) and machined into pin specimens. The pins were slid against nickel-based superalloy disks. Sliding velocities ranged from 0.27 to 10.0 m/s and temperatures from 25 to 900 C. Friction coefficients ranged from 0.25 to 0.40 and wear factors for the pin and disk were typically low 10(exp -5) cu mm/N-m. HIPped PM212 measured fully dense, whereas PM212/Au had 15 percent residual porosity. Examination of the microstructures with optical and scanning electron microscopy revealed the presence of pores in PM212/Au that were not present in PM212. Though the exact reason for the residual porosity in PM212/Au was not determined, it may be due to particle morphology differences between the gold and silver and their effect on powder metallurgy processing.

  15. Tribological and microstructural comparison of HIPped PM212 and PM212/Au self-lubricating composites

    NASA Technical Reports Server (NTRS)

    Bogdanski, Michael S.; Sliney, Harold E.; Dellacorte, Christopher

    1992-01-01

    The feasibility of replacing the silver with the volumetric equivalent of gold in the chromium carbide-based self-lubricating composite PM212 (70 wt percent NiCo-Cr3C2, 15 percent BaF2/CaF2 eutectic) was studied. The new composite, PM212/Au has the following composition: 62 wt percent NiCo-Cr3C2, 25 percent Au, 13 percent BaF2/CaF2 eutectic. The silver was replaced with gold to minimize the potential reactivity of the composite with possible environmental contaminants such as sulfur. The composites were fabricated by hot isostatic pressing (HIPping) and machined into pin specimens. The pins were slid against nickel-based superalloy disks. Sliding velocities ranged from 0.27 to 10.0 m/s and temperatures from 25 to 900 C. Frictions coefficients ranged from 0.25 to 0.40 and wear factors for the pin and disk were typically low 10(exp -5) cu mm/N-m. HIPped PM212 measured fully dense, whereas PM212/Au had 15 percent residual porosity. Examination of the microstructures with optical and scanning electron microscopy revealed the presence of pores in PM212/Au that were not present in PM212. Though the exact reason for the residual porosity PM212/Au was not determined, it may be due to practice morphology differences between the gold and silver and their effect on powder metallurgy processing.

  16. ELECTROLYTIC CORROSION OF GOLD AND THE FORMATION OF Au//2(SO//4)//3 IN CONCENTRATED SULFURIC ACID.

    USGS Publications Warehouse

    Senftle, Frank E.; Wright, Donald B.

    1985-01-01

    The authors have examined the direct anodic oxidation of gold in concentrated H//2SO//4 to more fully understand the chemical reactions. Au//2(SO//4)//3 is unstable and cannot be isolated for chemical analysis, but our experiments are consistent with the formation of Au//2(SO//4)//3 in concentrated H//2SO//4, in which it is stable. Equations describing chemical reactions which are compatible with the experimental data are presented.

  17. Isomorphism and solid solutions among Ag- and Au-selenides

    NASA Astrophysics Data System (ADS)

    Palyanova, Galina A.; Seryotkin, Yurii V.; Kokh, Konstantin A.; Bakakin, Vladimir V.

    2016-09-01

    Au-Ag selenides were synthesized by heating stoichiometric mixtures of elementary substances of initial compositions Ag2-xAuxSe with a step of x=0.25 (0≤x≤2) to 1050 °C and annealing at 500 °C. Scanning electron microscopy, optical microscopy, electron microprobe analysis and X-ray powder diffraction methods have been applied to study synthesized samples. Results of studies of synthesized products revealed the existence of three solid solutions with limited isomorphism Ag↔Au: naumannite Ag2Se - Ag1.94Au0.06Se, fischesserite Ag3AuSe2 - Ag3.2Au0.8Se2 and gold selenide AuSe - Au0.94Ag0.06Se. Solid solutions and AgAuSe phases were added to the phase diagram of Ag-Au-Se system. Crystal-chemical interpretation of Ag-Au isomorphism in selenides was made on the basis of structural features of fischesserite, naumannite, and AuSe.

  18. Direct Observation of Au Nanoclusters at Au/Si Interface and Enhanced SiO2 Growth Due to Catalytic Action by Au in Thermally Oxidized Au-Precipitated n-Type Si(001) Surfaces

    NASA Astrophysics Data System (ADS)

    Shimizu, Hirofumi; Kumamoto, Akihito; Imamura, Senji

    2013-04-01

    The behavior of Au nanoclusters at a Au/n-Si interface was investigated. In particular, SiO2 growth in thermally oxidized Au-precipitated n-type Si(001) surfaces was enhanced by the catalytic action of Au. When the Au-precipitated Si wafer was exposed to air for 30 d at room temperature (RT), a SiO2 film layer grew over Au nanoclusters on the Si surface. This is possibly because Si atoms may diffuse in an as-deposited Au layer and are oxidized in air at RT. In the case of oxidation at higher temperatures (850 °C for 30 min), Au nanoclusters were found to exist at the Au/n-Si interface. Moreover, the origin of protuberances observed by atomic force microscopy was found to be a bulge in the SiO2 film formed over the Au nanocluster, proving that the growth of the SiO2 film layer was enhanced by the catalytic action of Au.

  19. Anion and cation effects on the size control of Au nanoparticles prepared by sputter deposition in imidazolium-based ionic liquids.

    PubMed

    Hatakeyama, Yoshikiyo; Judai, Ken; Onishi, Kei; Takahashi, Satoshi; Kimura, Satoshi; Nishikawa, Keiko

    2016-01-28

    The sputter deposition of metals in an ionic liquid (IL) capture medium is a simple and elegant method for preparing nanoparticles without any chemical reaction. Although there have been some reports on the size determination factors for Au nanoparticles (AuNPs) prepared using this method, the effects with respect to the type of IL used have not been clearly elucidated. This is because there are some complicating factors, some of which have been revealed by our previous systematic studies. In the present study, we prepare AuNPs in nine types of imidazolium-based IL to examine the size determination effects of the type of anion involved, the length of the alkyl chain of the cation, and the preparation temperature for each IL, while keeping other factors constant. For most of the capture media ILs, the sizes of the AuNPs increase with an increase in temperature. The AuNPs prepared in ILs containing different types of anions exhibit distinctly different particle sizes and temperature dependences. Conversely, the alkyl chain is regarded as a secondary stabilizer that works only at higher preparation temperatures. We conclude that the sizes of AuNPs prepared by this method may be determined by the competition between the collision frequency of the ejected Au atoms and the stabilizing capability of the anions that form the first coordination shell around the AuNPs. The AuNP sizes are closely related to the volume of anions. PMID:26344691

  20. Multifunctional pDNA-Conjugated Polycationic Au Nanorod-Coated Fe3 O4 Hierarchical Nanocomposites for Trimodal Imaging and Combined Photothermal/Gene Therapy.

    PubMed

    Hu, Yang; Zhou, Yiqiang; Zhao, Nana; Liu, Fusheng; Xu, Fu-Jian

    2016-05-01

    It is very desirable to design multifunctional nanocomposites for theranostic applications via flexible strategies. The synthesis of one new multifunctional polycationic Au nanorod (NR)-coated Fe3 O4 nanosphere (NS) hierarchical nanocomposite (Au@pDM/Fe3 O4 ) based on the ternary assemblies of negatively charged Fe3 O4 cores (Fe3 O4 -PDA), polycation-modified Au nanorods (Au NR-pDM), and polycations is proposed. For such nanocomposites, the combined near-infrared absorbance properties of Fe3 O4 -PDA and Au NR-pDM are applied to photoacoustic imaging and photothermal therapy. Besides, Fe3 O4 and Au NR components allow the nanocomposites to serve as MRI and CT contrast agents. The prepared positively charged Au@pDM/Fe3 O4 also can complex plasmid DNA into pDNA/Au@pDM/Fe3 O4 and efficiently mediated gene therapy. The multifunctional applications of pDNA/Au@pDM/Fe3 O4 nanocomposites in trimodal imaging and combined photothermal/gene therapy are demonstrated using a xenografted rat glioma nude mouse model. The present study demonstrates that the proper assembly of different inorganic nanoparticles and polycations is an effective strategy to construct new multifunctional theranostic systems. PMID:26996155

  1. Selective electronalysis of peracetic acid in the presence of a large excess of H2O2 at Au(111)-like gold electrode.

    PubMed

    Awad, M I

    2012-06-12

    Peracetic acid (PAA) has been selectively electroanalyzed in the presence of a large excess of hydrogen peroxide (H(2)O(2)), about 500 fold that of PAA, using Au (111)-like gold electrode in acetate buffer solutions of pH 5.4. Au(111)-like gold electrode was prepared by a controlled reductive desorption of a previously assembled thiol, typically cysteine, monolayer onto the polycrystalline gold (poly-Au) electrode. Cysteine molecules were selectively removed from the Au(111) facets of the poly-Au electrode, keeping the other two facets (i.e., Au(110) and Au(100)) under the protection of the adsorbed cysteine. It has been found that Au(111)-like gold electrode positively shifts the reduction peak of PAA, while, fortunately, shifts the reduction peak of H(2)O(2) negatively, achieving a large potential separation (around 750 mV) between the two reduction peaks as compared with that (around 450 mV) obtained at the poly-Au electrode. This large potential separation between the two reduction peaks enabled the analysis of PAA in the presence of a large excess of H(2)O(2). In addition, the positive shift of the reduction peak of PAA gives the present method a high immunity against the interference of the dissolved oxygen. PMID:22632045

  2. Systematic Control of Self-Assembled Au Nanoparticles and Nanostructures Through the Variation of Deposition Amount, Annealing Duration, and Temperature on Si (111).

    PubMed

    Li, Ming-Yu; Sui, Mao; Pandey, Puran; Zhang, Quanzhen; Kim, Eun-Soo; Lee, Jihoon

    2015-12-01

    The size, density, and configurations of Au nanoparticles (NPs) can play important roles in controlling the electron mobility, light absorption, and localized surface plasmon resonance, and further in the Au NP-assisted nanostructure fabrications. In this study, we present a systematical investigation on the evolution of Au NPs and nanostructures on Si (111) by controlling the deposition amount (DA), annealing temperature (AT), and dwelling time (DT). Under an identical growth condition, the morphologies of Au NPs and nanostructures drastically evolve when the DA is only slightly varied, based on the Volmer-Weber and coalescence models: i.e. I: mini NPs, II: mid-sized round dome-shaped Au NPs, III: large Au NPs, and IV: coalesced nanostructures. With the AT control, three distinctive ranges are observed: i.e., NP nucleation, Au NPs maturation and melting. The gradual dimensional expansion of Au NPs is always compensated with the density reduction, which is explained with the thermodynamic theory. The DT effect is relatively minor on Au NPs, a sharp contrast to other metallic NPs, which is discussed based on the Ostwald-ripening. PMID:26428015

  3. Systematic Control of Self-Assembled Au Nanoparticles and Nanostructures Through the Variation of Deposition Amount, Annealing Duration, and Temperature on Si (111)

    NASA Astrophysics Data System (ADS)

    Li, Ming-Yu; Sui, Mao; Pandey, Puran; Zhang, Quanzhen; Kim, Eun-Soo; Lee, Jihoon

    2015-09-01

    The size, density, and configurations of Au nanoparticles (NPs) can play important roles in controlling the electron mobility, light absorption, and localized surface plasmon resonance, and further in the Au NP-assisted nanostructure fabrications. In this study, we present a systematical investigation on the evolution of Au NPs and nanostructures on Si (111) by controlling the deposition amount (DA), annealing temperature (AT), and dwelling time (DT). Under an identical growth condition, the morphologies of Au NPs and nanostructures drastically evolve when the DA is only slightly varied, based on the Volmer-Weber and coalescence models: i.e. I: mini NPs, II: mid-sized round dome-shaped Au NPs, III: large Au NPs, and IV: coalesced nanostructures. With the AT control, three distinctive ranges are observed: i.e., NP nucleation, Au NPs maturation and melting. The gradual dimensional expansion of Au NPs is always compensated with the density reduction, which is explained with the thermodynamic theory. The DT effect is relatively minor on Au NPs, a sharp contrast to other metallic NPs, which is discussed based on the Ostwald-ripening.

  4. A photoemission study of Au, Ge, and O{sub 2} deposition on NH{sub 4}F etched Si(111)

    SciTech Connect

    Terry, J.; Cao, R.; Wigren, C.; Pianetta, P.

    1994-03-01

    We have studied the interaction of a metal, Au, a semiconductor, Ge, and a non-metal, O{sub 2}, with the NH{sub 4}F etched Si(111) surface with photoemission spectroscopy. Two components were present in Si 2p core level spectra from the H-terminated surface. We observed the flat band condition from the as-etched, n-type, Si(111) surface. We performed stepwise depositions of Au and measured the band bending with photoemission spectroscopy. The Fermi level pinned near mid-gap as Au was deposited onto the as-etched surface. After the deposition of 1 ML of Au, a Au-silicide layer formed. This interfacial component indicated that the passivating H layer was compromised. As the Au coverage was increased, layers of pure Au formed between the bulk silicon and the Au-silicide layer. The observed behavior was nearly identical to that of Au deposition on the Si(111) 7 {times} 7 surface. Next, we tested the ability of the monohydride layer to sustain surfactant assisted growth of Ge. Ge islanding was observed at 400{degree}C indicating that good surfactant growth was not obtained. Although the monohydride layer was not a good surfactant for the Si(111) surface at this temperature, further study at different temperatures is needed to determine the ability of the ideal monohydride layer to act as a surfactant. Finally, we observed no oxidation of the as-etched surface at room temperature upon exposure to molecular oxygen.

  5. Au-nanoparticles grafted on plasma treated PE

    NASA Astrophysics Data System (ADS)

    Švorčík, V.; Chaloupka, A.; Řezanka, P.; Slepička, P.; Kolská, Z.; Kasálková, N.; Hubáček, T.; Siegel, J.

    2010-03-01

    Polyethylene (PE) surface was treated with Ar plasma. Activated surface was grafted from methanol solution of 1,2-ethanedithiol. Then the sample was immersed into freshly prepared colloid solution of Au-nanoparticles. Finally Au layer was sputtered on the samples. Properties of the modified PE were studied using various methods: AFM, EPR, RBS and nanoindentation. It was shown that the plasma treatment results in degradation of polymer chain (AFM) and creation of free radicals by EPR. After grafting with dithiol, the concentration of free radicals declines. The presence of Au and S in the surface layer after the coating with Au-nanoparticles was proved by RBS. Plasma treatment changes PE surface morphology and increases surface roughness, too. Another significant change in surface morphology and roughness was observed after deposition of Au-nanoparticles. Nanoindentation measurements show that the grafting with Au-nanoparticles increases adhesion of subsequently sputtered Au layer.

  6. Collision-spike Sputtering of Au Nanoparticles.

    PubMed

    Sandoval, Luis; Urbassek, Herbert M

    2015-12-01

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; the remainder is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering. PMID:26245857

  7. Collision-spike sputtering of Au nanoparticles

    SciTech Connect

    Sandoval, Luis; Urbassek, Herbert M.

    2015-08-06

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For this specific case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31% of the impact energy remains in the nanoparticles after impact; the remainder is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80% of that of free nanoparticles due to the suppression of forward sputtering.

  8. Collision-spike sputtering of Au nanoparticles

    DOE PAGESBeta

    Sandoval, Luis; Urbassek, Herbert M.

    2015-08-06

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For this specific case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31% of the impact energy remains in the nanoparticles after impact; the remaindermore » is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80% of that of free nanoparticles due to the suppression of forward sputtering.« less

  9. Tunable VO2/Au hyperbolic metamaterial

    NASA Astrophysics Data System (ADS)

    Prayakarao, S.; Mendoza, B.; Devine, A.; Kyaw, C.; van Dover, R. B.; Liberman, V.; Noginov, M. A.

    2016-08-01

    Vanadium dioxide (VO2) is known to have a semiconductor-to-metal phase transition at ˜68 °C. Therefore, it can be used as a tunable component of an active metamaterial. The lamellar metamaterial studied in this work is composed of subwavelength VO2 and Au layers and is designed to undergo a temperature controlled transition from the optical hyperbolic phase to the metallic phase. VO2 films and VO2/Au lamellar metamaterial stacks have been fabricated and studied in electrical conductivity and optical (transmission and reflection) experiments. The observed temperature-dependent changes in the reflection and transmission spectra of the metamaterials and VO2 thin films are in a good qualitative agreement with theoretical predictions. The demonstrated optical hyperbolic-to-metallic phase transition is a unique physical phenomenon with the potential to enable advanced control of light-matter interactions.

  10. Ds+/- meson production in Au+Au collisions at √{sNN} = 200 GeV in STAR

    NASA Astrophysics Data System (ADS)

    Zhou, Long; STAR Collaboration

    2015-10-01

    Heavy quarks, produced in hard scattering processes in the initial stages of the collisions, are considered as excellent probes for the strongly interacting deconfined medium formed in heavy-ion collisions. The Ds (c s / c s) production is affected by the strangeness enhancement and the primordial charm quark production. Thus the modification of the Ds meson spectra in ultra-relativistic heavy-ion collisions provides a new interesting probe to the key properties of the hot nuclear medium. The Heavy Flavor Tracker, installed in STAR in 2014, has been designed to extend STAR's capability of measuring heavy flavor production by the topological reconstruction of displaced decay vertices. It provides a unique opportunity for precise measurement of the Ds meson production. We will present the first measurement of Ds meson production via two decay channels Ds --> ϕ (1020) + π , and Ds --> K +K* (892) in Au+Au collisions at 200GeV. Preliminary results on the central-to-peripheral nuclear modification factor (Rcp) will also be presented. for the STAR Collaboration.

  11. D0 Production in Au +Au Collisions at √sNN = 200 GeV at STAR

    NASA Astrophysics Data System (ADS)

    Xie, Guannan; STAR Collaboration

    2015-10-01

    The mass of charm quarks is larger than the scales of the medium created in heavy-ion collisions at RHIC energies (mc > > ΛQCD,T,mu , d , s). This makes their production mainly feasible in the primordial nucleon-nucleon collisions, therefore, their final kinematics provide unique information on their interaction with the hot and dense medium produced in the early stages of heavy-ion collisions. Recent measurements of D0 nuclear modification factors shed light on the intricate interplay of Cold Nuclear Matter effects, hadronization mechanisms and energy loss of charm quarks in heavy-ion collisions. In this presentation, we will report D0 topological reconstruction via its golden hadronic decay channel (D0 -->K π) using STAR's recently installed Heavy Flavor Tracker (HFT) for reconstruction of secondary vertices. We will discuss studies of: HFT tracking efficiency from both data and simulation, D0 background reconstruction techniques, and the optimizations of D0 cuts using TMVA toolkit. The transverse-momentum and centrality dependence of D0 production in Au+Au Collisions at 200 GeV will be presented. We will also discuss nuclear modification factors and their comparison with published data from RHIC and the LHC and finally compare the results with models.

  12. Electrophoretic deposition on graphene of Au nanoparticles generated by laser ablation of a bulk Au target in water

    NASA Astrophysics Data System (ADS)

    Semaltianos, N. G.; Hendry, E.; Chang, H.; Wears, M. L.

    2015-04-01

    The characteristic property of nanoparticles generated by laser ablation of metallic targets in liquids to be surface electrically charged can be exploited for the deposition of the nanoparticles onto electrically conducting substrates directly from the synthesized colloidal solution by using the method of electrophoretic deposition (EPD). The method benefits from the high quality of the interface between the deposited nanoparticles and the substrate due to the ligand-free nanoparticle surfaces and thus providing hybrid materials with advanced and novel properties. In this letter, an Au bulk target was laser ablated in deionized (DI) water for the generation of an Au nanoparticle colloidal solution. Under the present conditions of ablation, nanoparticles with diameters from 4 and up to 67 nm are formed in the solution with 80% of the nanoparticles having diameters below ~20 nm. Their size distribution follows a log-normal function with a median diameter of 8.6 nm. The nanoparticles were deposited onto graphene on a quartz surface by anodic EPD performed at 30 V for 20 min and a longer time of 1 h. A quite uniform surface distribution of the nanoparticles was achieved with surface densities ranging from ~15 to ~40 nanoparticles per μm2. The hybrid materials exhibit clearly the plasmon resonance absorption of the Au nanoparticles. Deposition for short times preserves the integrity of graphene while longer time deposition leads to the conversion of graphene to graphene oxide, which is attributed to the electrochemical oxidation of graphene.

  13. Comments on momentum aperture of 100 GeV/n Au runs in RHIC

    SciTech Connect

    Zhang, S.Y.

    2011-11-01

    In RHIC 2010 100 GeV/n Au run, the momentum aperture has been an issue in the re-bucketing and the beam intensity lifetime in store. Both Blue and Yellow beams with comparable storage RF voltage and peak current have suffered more beam loss than in Run 2007. In this note, some comments are made for the momentum aperture of the lattices used from the Au runs in 2007, 2008 and 2010. From the wigglings and the beam decays of each lattice, information regarding the machine momentum aperture is presented. Several directions in further improvement are discussed.

  14. Nanoporous bimetallic Pt-Au alloy nanocomposites with superior catalytic activity towards electro-oxidation of methanol and formic acid.

    PubMed

    Zhang, Zhonghua; Wang, Yan; Wang, Xiaoguang

    2011-04-01

    We present a facile route to fabricate novel nanoporous bimetallic Pt-Au alloy nanocomposites by dealloying a rapidly solidified Al(75)Pt(15)Au(10) precursor under free corrosion conditions. The microstructure of the precursor and the as-dealloyed sample was characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, and energy dispersive X-ray (EDX) analysis. The Al(75)Pt(15)Au(10) precursor is composed of a single-phase Al(2)(Au,Pt) intermetallic compound, and can be fully dealloyed in a 20 wt.% NaOH or 5 wt.% HCl aqueous solution. The dealloying leads to the formation of the nanoporous Pt(60)Au(40) nanocomposites (np-Pt(60)Au(40) NCs) with an fcc structure. The morphology, size and crystal orientation of grains in the precursor can be conserved in the resultant nanoporous alloy. The np-Pt(60)Au(40) NCs consist of two zones with distinct ligament/channel sizes and compositions. The formation mechanism of these np-Pt(60)Au(40) NCs can be rationalized based upon surface diffusion of more noble elements and spinodal decomposition during dealloying. Electrochemical measurements demonstrate that the np-Pt(60)Au(40) NCs show superior catalytic activity towards the electro-oxidation of methanol and formic acid in the acid media compared to the commercial JM-Pt/C catalyst. This material can find potential applications in catalysis related areas, such as direct methanol or formic acid fuel cells. Our findings demonstrate that dealloying is an effective and simple strategy to realize the alloying of immiscible systems under mild conditions, and to fabricate novel nanostructures with superior performance. PMID:21311802

  15. Analysis of the residual linewidth in electron-paramagnetic resonance of AuEr and AuYb

    NASA Astrophysics Data System (ADS)

    Spalden, Y. von; Baberschke, K.

    1981-04-01

    For single crystals of AuEr and polycrystalline AuYb the residual EPR linewidth due to inhomogeneous broadening is analyzed. Angular dependent experiments show uniquely that the main contribution is due to internal strain rather than to dipolar interaction. The independent experiments for AuEr and AuYb yield a consistent set of parameters but show a dipolar contribution two to three times smaller than calculated. An explanation for this is given. The very precise determination of Hres yields |Δg | = |ρJ1| < 0.005 for AuEr, a vanishing g-shift.

  16. Obtaining Au thin films in atmosphere of reactive nitrogen through magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Quintero, J. H.; Ospina, R.; Mello, A.

    2016-02-01

    4d and 5d series of the transition metals are used to the obtaining nitrides metallic, due to the synthesis of PtN, AgN and AuN in the last years. Different nitrides are obtained in the Plasma Assisted Physics Vapour Deposition system, due to its ionization energy which is necessary for their formation. In this paper a Magnetron Sputtering system was used to obtain Au thin films on Si wafers in Nitrogen atmosphere. The substrate temperature was varied between 500 to 950°C. The samples obtained at high temperatures (>500°C) show Au, Si and N elements, as it is corroborated in the narrow spectrum obtained for X-Ray Photoelectron Spectroscopy; besides the competition of orientation crystallographic texture between (111) and (311) directions was present in the X-Ray Diffraction analysis to the sample heated at 950°C.

  17. Ab initio study of small Au nY 2 ( n=1-4) clusters

    NASA Astrophysics Data System (ADS)

    Jian-Jun, Guo; Ji-Xian, Yang; Dong, Die

    2008-11-01

    The geometries of the lowest-lying isomers of Au nY 2 ( n=1-4) clusters are determined systematically via the density functional method B3LYP with relativistic effective core potentials (RECP) and LANL2DZ basis set. Several low-lying isomers were determined, and many of them in electronic configurations with a high-spin multiplicity. The gold-yttrium interaction is strong enough to modify the known growth pattern of bare gold clusters. The stability trend of Y-doped Au n clusters is compared to that of pure Au n clusters. The results show that the inclusion of two Y atoms in the clusters improves the cluster stability, and indicate higher stability as the structures grow in size. The present calculations are useful to understand the enhanced catalytic activity and selectivity gained by using yttrium-doped gold catalyst.

  18. Growth of Au on Ni(110): A Semiempirical Modeling of Surface Alloy Phases

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ibanez-Meier, Rodrigo; Ferrante, John

    1995-01-01

    Recent experiments using scanning tunneling microscopy show evidence for the formation of surface alloys of otherwise immiscible metals. Such is the case for Au deposited in Ni(110), where experiments by Pleth Nielsen el al.indicate that at low Au coverage (less than 0. 5 ML), Au atoms replace Ni atoms in the surface layer forming a surface alloy while the Ni atoms form islands on the surface. In this paper, we present results of a theoretical modeling of this phenomenon using the recently developed Bozzolo-Ferrante-Smith method for alloys. We provide results of an extensive analysis of the growth process that strongly support the conclusions drawn from the experiment: at very low coverages, there is a tendency for dimer formation on the overlayer, which later exchange positions with Ni atoms in the surface layer, thus accounting for the large number of substituted dimers. Ni island formation as well as other alternative short-range-order patterns are discussed.

  19. Growth of Au on Ni(110): a BFS Modelling of Surface Alloy Phases

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ibanez-Meier, Rodrigo; Ferrante, John

    1994-01-01

    Recent experiments using scanning tunneling microscopy show evidence for the formation of surface alloys of otherwise immiscible metals. Such is the case for Au deposited in Ni(11), where experiments by Pleth Nielsen et al. indicate that at low Au coverage (less than 0.5 ML), Au atoms replace Ni atoms in the surface layer forming a surface alloy while the Ni atoms form islands on the surface. In this work, we present results of a theoretical modeling of this phenomenon using the recently developed BFS method for alloys. We provide results of an extensive analysis of the growth process which strongly support the conclusions drawn from the experiment; at very low coverages, there is tendency for dimer formation on the overlayer, which later exchange positions with Ni atoms in the surface layer, thus accounting for the large number of substituted dimers. Ni island formations as well as other alternative short range order patterns are discussed.

  20. Self-assembly of methanethiol on cluster arrays of Co/Au(111)

    NASA Astrophysics Data System (ADS)

    Nenchev, Georgi; Diaconescu, Bogdan; Pohl, Karsten

    2007-03-01

    Self-assembly on strained metallic interfaces is an attractive option for growing highly ordered multi-functional nanopatterns. We present a Variable Temperature STM and Auger Electron Spectroscopy study of selective adsorption of sulfur-terminated CH3SH molecules on the lattice of Co clusters on Au(111). We investigate the growth of a uniform network of Co on the reconstructed Au(111) surface, the temperature evolution of the island height and the termination, and the onset of surface alloying. Further we will show the evolution of morphology of the CH3SH film on Au (111) as a function of coverage and temperature, and the importance of the herringbone reconstruction for the SAM formation and orientation. Successful combination and control of these two processes leads to the creation of an ordered, stable patterned Co/CH3SH heterostructure with nanometer-sized unit cell.

  1. Self-assembly of methanethiol on the reconstructed Au(111) surface

    NASA Astrophysics Data System (ADS)

    Nenchev, Georgi; Diaconescu, Bogdan; Hagelberg, Frank; Pohl, Karsten

    2009-08-01

    We present a combined experimental and theoretical study of molecular methanethiol (CH3SH) adsorption on the reconstructed Au(111) surface in the temperature range between 90 and 300 K in UHV. We find that the simplest thiol molecules form two stable self-assembled monolayer (SAM) structures that are created by distinct processes. Below 120 K, a solid rectangular phase, preserving the herringbone reconstruction, emerges from individual chains of spontaneously formed dimers. At higher adsorption temperatures below 170 K, a close-packed phase forms via dissociative CH3SH adsorption and the formation of Au adatoms that are not incorporated into the SAM. We show that the combination of a strong substrate-mediated interaction with nondissociative dimerization and temperature activated removal of the Au(111) reconstruction drives the large-scale assembly of molecular CH3SH into two distinct phases.

  2. Interaction of oxygen with the (111) surface of NaAu2

    NASA Astrophysics Data System (ADS)

    Kwolek, Emma J.; Widmer, Roland; Gröning, Oliver; Deniz, Okan; Walen, Holly; Yuen, Chad D.; Huang, Wenyu; Schlagel, Deborah L.; Wallingford, Mark; Brundle, C. R.; Thiel, Patricia A.

    2016-08-01

    NaAu2, in powder form, is known to be an active catalyst for CO oxidation. The goal of the present study is to elucidate the interaction of one reactant, molecular oxygen, with a single-crystal surface of this material, NaAu2(111). Exposing the clean surface to gas-phase molecular oxygen produces three types of oxygen on the surface. One type is bound in spurious carbonate that forms during exposure. The second is adsorbed atomic oxygen that interacts both with Na and Au. The third type is atomic oxygen that interacts mainly or only with Na. We propose that the last species is an oxide of Na distributed throughout the surface and near-surface region. Its formation is accompanied by surface segregation of Na.

  3. A highly crystalline single Au wire network as a high temperature transparent heater.

    PubMed

    Rao, K D M; Kulkarni, Giridhar U

    2014-06-01

    A transparent conductor which can generate high temperatures finds important applications in optoelectronics. In this article, a wire network made of Au on quartz is shown to serve as an effective high temperature transparent heater. The heater has been fabricated by depositing Au onto a cracked sacrificial template. The highly interconnected Au wire network thus formed exhibited a transmittance of ∼87% in a wide spectral range with a sheet resistance of 5.4 Ω □(-1). By passing current through the network, it could be joule heated to ∼600 °C within a few seconds. The extraordinary thermal performance and stability owe much to the seamless junctions present in the wire network. Furthermore, the wire network gets self-annealed through joule heating as seen from its increased crystallinity. Interestingly, both transmittance and sheet resistance improved following annealing to 92% and 3.2 Ω □(-1), respectively. PMID:24756335

  4. Sensitive voltammetric determination of vanillin with an AuPd nanoparticles-graphene composite modified electrode.

    PubMed

    Shang, Lei; Zhao, Faqiong; Zeng, Baizhao

    2014-05-15

    In this work, graphene oxide was reduced to graphene with an endogenous reducing agent from dimethylformamide, and then AuPd alloy nanoparticles were electrodeposited on the graphene film. The obtained AuPd-graphene hybrid film was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and voltammetry. The electrochemical behavior of vanillin was studied using the AuPd-graphene hybrid based electrode. It presented high electrocatalytic activity and vanillin could produce a sensitive oxidation peak at it. Under the optimal conditions, the peak current was linear to the concentration of vanillin in the ranges of 0.1-7 and 10-40 μM. The sensitivities were 1.60 and 0.170 mA mM(-1) cm(-2), respectively; the detection limit was 20 nM. The electrode was successfully applied to the detection of vanillin in vanilla bean, vanilla tea and biscuit samples. PMID:24423501

  5. Crystalline monolayer surface of liquid Au-Cu-Si-Ag-Pd: Metallic glass former

    SciTech Connect

    Mechler, S; Yahel, E; Pershan, P S; Meron, M; Lin, B

    2012-02-06

    It is demonstrated by means of x-ray synchrotron reflectivity and diffraction that the surface of the liquid phase of the bulk metallic glass forming alloy Au49Cu26.9Si16.3Ag5.5Pd2.3 consists of a two-dimensional crystalline monolayer phase for temperatures of up to about 50 K above the eutectic temperature. The present alloy as well as glass forming Au82Si18 and Au-Si-Ge alloys containing small amounts of Ge are the only metallic liquids to exhibit surface freezing well above the melting temperature. This suggests that the phenomena of surface freezing in metallic liquids and glass forming ability are related and probably governed by similar physical properties.

  6. Development of Au-Ag nanowire mesh fabrication by UV-induced approach

    SciTech Connect

    Saggar, Siddhartha; Predeep, Padmanabhan

    2014-10-15

    In an attempt to overcome the limitations of the presently prevailing transparent conducting electrode (TCE) - indium tin oxide (ITO) - many materials have been considered for replacing ITO. Recently, a novel method has been reported for the synthesis of Au-Ag nanowire (NW) mesh, and tested successfully for organic-light-emitting-diodes (OLEDs). It employs UV-induced reduction of gold- and silver- precursors to form Au-Ag NW mesh. In this report, Au-Ag NW mesh thin films are synthesized on glass substrates with an objective for use as facing-electrode for Organic Photovoltaics. Various issues and factors affecting the fabrication-process have been improved, and are also discussed here. The electrode showed good transmitivity, of around 95% (excluding that of glass substrate). The advantage of the technique is its simple processing method and cost-effectiveness.

  7. Synthesis of vinyl-terminated Au nanoprisms and nanooctahedra mediated by 3-butenoic acid: direct Au@pNIPAM fabrication with improved SERS capabilities

    NASA Astrophysics Data System (ADS)

    Casado-Rodriguez, M. A.; Sanchez-Molina, M.; Lucena-Serrano, A.; Lucena-Serrano, C.; Rodriguez-Gonzalez, B.; Algarra, M.; Diaz, A.; Valpuesta, M.; Lopez-Romero, J. M.; Perez-Juste, J.; Contreras-Caceres, R.

    2016-02-01

    Here we describe the first seedless synthesis of vinyl-terminated Au nanotriangular prisms (AuNTPs) and nanooctahedra (AuNOC) in aqueous media. This synthesis is performed by chemical reduction of chloroauric acid (HAuCl4) with 3-butenoic acid (3BA) in the presence of benzyldimethylammonium chloride (BDAC). The principal novelties of the presented method are the use of a mixture of 3BA and BDAC, the synthesis of gold prisms and octahedra with controllable size, and the presence of terminal double bonds on the metal surface. Initially this method produces a mixture of triangular gold nanoprisms and octahedra; however, both morphologies are successfully separated by surfactant micelle induced depletion interaction, reaching percentages up to ~90%. Moreover, the alkene moieties present on the gold surface are exploited for the fabrication of hybrid core@shell particles. Gold octahedra and triangular prisms are easily encapsulated by free radical polymerization of N-isopropylacrylamide (NIPAM). Finally, in order to obtain a gold core with the most number of tips, AuNTP@pNIPAM microgels were subjected to gold core overgrowth, thus resulting in star-shaped nanoparticles (AuSTs@pNIPAM). We use 4-amino-benzenethiol as the model analyte for SERS investigations. As expected, gold cores with tips and high curvature sites produced the highest plasmonic responses.Here we describe the first seedless synthesis of vinyl-terminated Au nanotriangular prisms (AuNTPs) and nanooctahedra (AuNOC) in aqueous media. This synthesis is performed by chemical reduction of chloroauric acid (HAuCl4) with 3-butenoic acid (3BA) in the presence of benzyldimethylammonium chloride (BDAC). The principal novelties of the presented method are the use of a mixture of 3BA and BDAC, the synthesis of gold prisms and octahedra with controllable size, and the presence of terminal double bonds on the metal surface. Initially this method produces a mixture of triangular gold nanoprisms and octahedra; however

  8. Assembly of hybrid oligonucleotide modified gold (Au) and alloy nanoparticles building blocks.

    PubMed

    Kuo, Yu-Ching; Jen, Chun-Ping; Chen, Yu-Hung; Su, Chia-Hao; Tsai, Shu-Hui; Yeh, Chen-Sheng

    2006-01-01

    The alloy-based hybrid materials with macroscopic network arrays were developed by AuAg/Au and AuAgPd/Au nanoparticle composites through oligonucleotides hybridization. AuAg/Au and AuAgPd/Au exhibited distinct organization. The morphology of AuAg/Au conjugation assembled mainly as compact aggregates while AuAgPd/Au hybrid conjugated into the loosen network assemblies. The dehybridization temperatures were studied as a function of molar ratio of alloy/Au. It was found that higher alloy/gold molar ratio led to stronger hybridization for alloy/gold composite, accompanied with increased melting temperature. These results could be interpreted in terms of more alloy nanoparticles bound to a Au particle when the molar ratio of alloy/gold increased. The thermal analysis also showed that AuAg/Au exhibited higher dehybridization temperature. A modified model describing the dehybridization probability of an intact Au/alloy aggregate was performed to support the dehybridization temperature increased with increasing alloy/Au molar ratio. As to more oligonucleotides carried by AuAg (4.9 +/- 1.9 nm) than by AuAgPd (4.4 +/- 1.5 nm) due to larger size in AuAg, the efficient hybridization could result in higher dehybridization temperature in AuAg/Au. PMID:16573077

  9. The effect of low Au concentrations on the properties of eutectic Sn/Pb

    SciTech Connect

    Kramer, P.A.

    1992-05-01

    This study was of the effects moderately low Au concentrations ({le} 10 wt%) have on the mechanical properties and microstructure of an eutectic Sn/Pb alloy. Vibration (60--90 Hz swept sine wave for 30 hours) and thermal cycling (0--110C for 1450 cycles) reliability tests were performed on fine pitch leaded chip carriers using eutectic Sn/Pb solder on PCBs (printed circuit boards) with 0, 5, 10, 20, and 50{mu}in nominal Au thicknesses. Testing was also performed on double shear creep specimens consisting of arrays of regular pitch joints. There was a dramatic increase in the number of joints containing voids with increasing Au concentration, an effect more pronounced in the creep joints than in the reliability joints. These voids tended to coalesce and grow during rework simulation of the reliability joints. AuSn{sub 4} intermetallics present in toe of 4.8 wt% (50 {mu}in) Au vibration joints rotated from initial vertical perpendicular to surface of PCB metallization, solidification positions to roughly horizontal (parallel to plating surface) orientations during rework simulation and during aging of the parts. The AuSn{sub 4} intermetallics in the toe of the 4.8 wt% (50{mu}in) Au reflowed joints also rotated after vibration testing. No joint failures were observed in either vibration tested or thermally cycled specimens. Cracks formed in some of the vibration tested specimen joints under the heel of the gull-wing lead at Pb-rich phases. Thermally cycled specimens showed eutectic microstructure and intermetallic coarsening without crack formation. Creep tests showed loss of the superplasticity in eutectic Sn/Pb alloys with even the lowest Au concentration tested of 0.2 wt% Au. Intermetallic rotation was not a factor in crack propagation, but void presence was. Cracks tended to form in joints containing voids before forming in void-free joints. Crack propagation followed Sn/Sn grain boundaries and Sn/Pb phase boundaries from Pb-rich phase to Pb-rich phase.

  10. Multifunctional compact hybrid Au nanoshells: a new generation of nanoplasmonic probes for biosensing, imaging, and controlled release.

    PubMed

    Jin, Yongdong

    2014-01-21

    Gold nanoshells (AuNSs) with tunable localized surface plasmon resonance (LSPR) peaks in the near-infrared (NIR) region possess unique optical properties-particularly that soft tissues are "transparent" at these wavelengths-making them of great interest in cancer diagnosis and treatment. Since 1998 when Halas and co-workers invented the first generation of AuNS, with a silica core and Au shell, researchers have studied and designed AuNSs for theranostic-individualized, combination diagnosis and therapy-nanomedicine. As demand has increased for more powerful and practical theranostic applications, so has demand for the next generation of AuNSs-compact yet complex multifunctional AuNSs with finely integrated plasmonic and nonplasmonic inorganic components. For in vivo biomedical applications, such a hybrid AuNS offers the desirable optical properties of NIR LSPR. Size, however, has proved a more challenging parameter to control in hybrid AuNSs. The ideal size of therapeutic NPs is 10-100 nm. Larger particles have limited diffusion in the extracellular space, while particles less than 5 nm are rapidly cleared from the circulation through extravasation or renal clearance. Conventional methods of preparing AuNS have failed to obtain small-sized hybrid AuNSs with NIR LSPR responses. In this Account, we present a new class of multifunctional hybrid AuNSs with ultrathin AuNSs and varied, functional (nonplasmonic) core components ranging from "hard" semiconductor quantum dots (QDs), to superparamagnetic NPs, to "soft" liposomes made using poly-l-histidine as a template to direct Au deposition. The resultant hybrid AuNSs are uniform and compact (typically 15-60 nm) but also preserve the optical properties and shell-type NIR response necessary for biomedical use. We also demonstrate these particles' innovative plasmonic applications in biosensing, multimodal imaging and controlled release. More importantly, the magnetic-plasmonic Fe3O4/Au core-shell NP enables a new

  11. Unwinding Au(+)···Au(+) Bonded Filaments in Ligand-Supported Gold(I) Polymer under Pressure.

    PubMed

    Paliwoda, Damian; Wawrzyniak, Paulina; Katrusiak, Andrzej

    2014-07-01

    The ultimately thin single-strand gold filaments, of Au(+)···Au(+) bonded gold(I) diethyldithiocarbamate polymer, AuEt2DTC, can be transformed depending on pressure and solvate contents. When synthesized in the presence of CH2Cl2, it crystallizes into a tetragonal AuEt2DTC·xCH2Cl2 phase α with ligand-supported and unsupported Au(+)···Au(+) bonded filaments modulated into molecular Au8-pitch helices. Low contents of CH2Cl2 favors the β phase of significantly reduced volume and orthorhombic space group Fddd. The α-AuEt2DTC·xCH2Cl2 crystal exhibits a highly unusual negative-area compressibility, due to the spring-like compression of helices. Above 0.05 GPa, the crystal transforms to phase β, where the Au16-pitch helices partly unwind their turns, which relaxes the tension generated by external pressure between neighboring helices of the opposite handedness. This is a unique observation of atomic-scale helical filaments transformation, which otherwise is a universal process analogous to the helix reversal between DNA forms B and Z, and in macroscopic world it is similar to nonperiodic unwind kinks in grapevine tendrils and telephone cords. Pressure also reduces the differences between the ligand-supported and unsupported Au(+)···Au(+) bonds. PMID:26279531

  12. Virus-templated Au and Au/Pt Core/shell Nanowires and Their Electrocatalytic Activitives for Fuel Cell Applications

    PubMed Central

    LEE, YOUJIN; KIM, JUNHYUNG; YUN, DONG SOO; NAM, YOON SUNG; SHAO-HORN, YANG; BELCHER, ANGELA M.

    2014-01-01

    A facile synthetic route was developed to make Au nanowires (NWs) from surfactant-mediated bio-mineralization of a genetically engineered M13 phage with specific Au binding peptides. From the selective interaction between Au binding M13 phage and Au ions in aqueous solution, Au NWs with uniform diameter were synthesized at room temperature with yields greater than 98 % without the need for size selection. The diameters of Au NWs were controlled from 10 nm to 50 nm. The Au NWs were found to be active for electrocatalytic oxidation of CO molecules for all sizes, where the activity was highly dependent on the surface facets of Au NWs. This low-temperature high yield method of preparing Au NWs was further extended to the synthesis of Au/Pt core/shell NWs with controlled coverage of Pt shell layers. Electro-catalytic studies of ethanol oxidation with different Pt loading showed enhanced activity relative to a commercial supported Pt catalyst, indicative of the dual functionality of Pt for the ethanol oxidation and Au for the anti-poisoning component of Pt. These new one-dimensional noble metal NWs with controlled compositions could facilitate the design of new alloy materials with tunable properties. PMID:24910712

  13. Energy dependence of Kπ, pπ and Kp fluctuations in Au+Au collisions from √sNN=7.7 to 200 GeV

    SciTech Connect

    Adamczyk, L.

    2015-08-07

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical Kπ, pπ, and Kp fluctuations as measured by the STAR experiment in central 0–5% Au+Au collisions from center-of-mass collision energies √sNN=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude of the dynamical fluctuations in event-by-event measurements of the Kπ, pπ, and Kp pairs. The energy dependences of these fluctuations from central 0–5% Au+Au collisions all demonstrate a smooth evolution with collision energy.

  14. Energy dependence of K π , p π , and K p fluctuations in Au + Au collisions from √{sN N}=7.7 to 200 GeV

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandin, A. V.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; S'anchez, M. Calder'on de la Barca; campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Cheng, J.; Cherney, M.; Christie, W.; Codrington, M. J. M.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, H. Z.; Huang, B.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, W.; Li, Z. M.; Li, C.; Li, Y.; Li, X.; Li, X.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, L.; Ma, R.; Ma, G. L.; Ma, Y. G.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Meehan, K.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D. L.; Page, B. S.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peterson, A.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, M. K.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B. J.; Sun, Z.; Sun, Y.; Sun, X. M.; Sun, X.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Tawfik, A. N.; Thomas, J. H.; Tian, J.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, Y.; Wang, F.; Wang, J. S.; Wang, H.; Wang, G.; Wang, Y.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, N.; Xu, H.; Xu, Y. F.; Xu, Q. H.; Xu, Z.; Yang, Y.; Yang, S.; Yang, C.; Yang, Y.; Yang, Q.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.; Zhang, Y.; Zhang, S.; Zhang, X. P.; Zhang, J. B.; Zhang, J. L.; Zhang, Z.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2015-08-01

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the BNL Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical K π , p π , and K p fluctuations as measured by the STAR experiment in central 0-5% Au + Au collisions from center-of-mass collision energies √{sN N}=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude of the dynamical fluctuations in event-by-event measurements of the K π , p π , and K p pairs. The energy dependences of these fluctuations from central 0-5% Au + Au collisions all demonstrate a smooth evolution with collision energy.

  15. Centrality dependence of freeze-out parameters from Au+Au collisions at sqrt {s_{NN} } = 7.7, 11.5 and 39 GeV

    NASA Astrophysics Data System (ADS)

    Kumar, Lokesh

    2012-12-01

    The RHIC beam energy scan program in its first phase collected data for Au+Au collisions at beam energies of 7.7, 11.5 and 39 GeV. The event statistics collected at these lower energies allow us to study the centrality dependence of various observables in detail, and compare to fixed-target experiments at SPS for similar beam energies. The chemical and kinetic freeze-out parameters can be extracted from the experimentally measured yields of identified hadrons within the framework of thermodynamical models. These then provide information about the system at the stages of the expansion where inelastic and elastic collisions of the constituents cease. We present the centrality dependence of freeze-out parameters for Au+Au collisions at midrapidity for sqrt {s_{NN} } = 7.7, 11.5, and 39 GeV from the STAR experiment. The chemical freeze-out conditions are obtained by comparing the measured particle ratios (involving π, K, p, and p) to those from the statistical thermal model calculations. The kinetic freeze-out conditions are extracted at these energies by simultaneously fitting the invariant yields of identified hadrons ( π, K, and p) using Blast Wave model calculations.

  16. Centrality dependence of freeze-out parameters from Au+Au collisions at sqrt {s_{NN} } = 7.7, 11.5 and 39 GeV

    NASA Astrophysics Data System (ADS)

    Kumar, Lokesh

    2012-12-01

    The RHIC beam energy scan program in its first phase collected data for Au+Au collisions at beam energies of 7.7, 11.5 and 39 GeV. The event statistics collected at these lower energies allow us to study the centrality dependence of various observables in detail, and compare to fixed-target experiments at SPS for similar beam energies. The chemical and kinetic freeze-out parameters can be extracted from the experimentally measured yields of identified hadrons within the framework of thermodynamical models. These then provide information about the system at the stages of the expansion where inelastic and elastic collisions of the constituents cease. We present the centrality dependence of freeze-out parameters for Au+Au collisions at midrapidity for sqrt {s_{NN} } = 7.7, 11.5, and 39 GeV from the STAR experiment. The chemical freeze-out conditions are obtained by comparing the measured particle ratios (involving π, K, p, and p) to those from the statistical thermal model calculations. The kinetic freeze-out conditions are extracted at these energies by simultaneously fitting the invariant yields of identified hadrons (π, K, and p) using Blast Wave model calculations.

  17. Centrality Dependence of Charged Hadron Transverse Momentum Spectra in Au+Au Collisions from √(sNN)=62.4 to 200 GeV

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Halliwell, C.; Hamblen, J.; Hauer, M.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Seals, H.; Sedykh, I.; Smith, C. E.; Stankiewicz, M. A.; Steinberg, P.; Stephans, G. S.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wenger, E.; Wolfs, F. L.; Wosiek, B.; Woźniak, K.; Wysłouch, B.

    2005-03-01

    We have measured transverse momentum distributions of charged hadrons produced in Au+Au collisions at √(sNN)=62.4 GeV. The spectra are presented for transverse momenta 0.25Au+Au collisions at √(sNN)= 130 and 200 GeV. In contrast to the large change in RAA, we observe a very similar centrality evolution of the pT spectra at √(sNN)=62.4 and 200 GeV. The dynamical origin of this surprising factorization of energy and centrality dependence of particle production in heavy-ion collisions remains to be understood.

  18. High Transverse Momentum Triggered Correlations over a Large Pseudorapidity Acceptance in Au+Au Collisions at sNN=200GeV

    NASA Astrophysics Data System (ADS)

    Alver, B.; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Chai, Z.; Chetluru, V.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Halliwell, C.; Hamblen, J.; Hauer, M.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Li, W.; Lin, W. T.; Loizides, C.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Seals, H.; Sedykh, I.; Smith, C. E.; Stankiewicz, M. A.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Walters, P.; Wenger, E.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wysłouch, B.

    2010-02-01

    A measurement of two-particle correlations with a high transverse momentum trigger particle (pTtrig>2.5GeV/c) is presented for Au+Au collisions at sNN=200GeV over the uniquely broad longitudinal acceptance of the PHOBOS detector (-4<Δη<2). A broadening of the away-side azimuthal correlation compared to elementary collisions is observed at all Δη. As in p+p collisions, the near side is characterized by a peak of correlated partners at small angle relative to the trigger particle. However, in central Au+Au collisions an additional correlation extended in Δη and known as the “ridge” is found to reach at least |Δη|≈4. The ridge yield is largely independent of Δη over the measured range, and it decreases towards more peripheral collisions. For the chosen pTtrig cut, the ridge yield is consistent with zero for events with less than roughly 100 participating nucleons.

  19. Non-flow correlations and elliptic flow fluctuations in Au+Au collisions at sNN=200 GeV

    NASA Astrophysics Data System (ADS)

    Alver, B.; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Busza, W.; Carroll, A.; Chai, Z.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Halliwell, C.; Hamblen, J.; Hauer, M.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Li, W.; Lin, W. T.; Loizides, C.; Manly, S.; Mignerey, A. C.; Nouicer, R.; Olszewski, A.; Pak, R.; Reed, C.; Roland, C.; Roland, G.; Sagerer, J.; Seals, H.; Sedykh, I.; Smith, C. E.; Stankiewicz, M. A.; Steinberg, P.; Stephans, G. S. F.; Sukhanov, A.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Walters, P.; Wenger, E.; Wolfs, F. L. H.; Wosiek, B.; Woźniak, K.; Wysłouch, B.

    2010-03-01

    This article presents results on event-by-event elliptic flow fluctuations in Au+Au collisions at sNN= 200 GeV, where the contribution from non-flow correlations has been subtracted. An analysis method is introduced to measure non-flow correlations, relying on the assumption that non-flow correlations are most prominent at short ranges (|Δη|<2). Assuming that non-flow correlations are of the order that is observed in p+p collisions for long-range correlations (|Δη|>2), relative elliptic flow fluctuations of approximately 30-40% are observed. These results are consistent with predictions based on spatial fluctuations of the participating nucleons in the initial nuclear overlap region. It is found that the long-range non-flow correlations in Au+Au collisions would have to be more than an order of magnitude stronger compared to the p+p data to lead to the observed azimuthal anisotropy fluctuations with no intrinsic elliptic flow fluctuations.

  20. Measurement of Υ(1S + 2S +3S) production in p + p and Au + Au collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV

    SciTech Connect

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Bataineh, H.; Al-Ta'ani, H.; Alexander, J.; Angerami, A.; Aoki, K.; Apadula, N.; Aphecetche, L.; Aramaki, Y.; Asai, J.; Asano, H.; Aschenauer, E. C.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Baldisseri, A.; Bannier, B.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Batsouli, S.; Baublis, V.; Baumann, C.; Baumgart, S.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bickley, A. A.; Bing, X.; Blau, D. S.; Boissevain, J. G.; Bok, J. S.; Borel, H.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Castera, P.; Chang, B. S.; Chang, W. C.; Charvet, J. -L.; Chen, C. -H.; Chernichenko, S.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choi, S.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Churyn, A.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Connors, M.; Constantin, P.; Csanád, M.; Csörgő, T.; Dahms, T.; Dairaku, S.; Das, K.; Datta, A.; Daugherity, M. S.; David, G.; Denisov, A.; d'Enterria, D.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Ding, L.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Dubey, A. K.; Durham, J. M.; Durum, A.; Dutta, D.; Dzhordzhadze, V.; D'Orazio, L.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Eyser, K. O.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Gainey, K.; Gal, C.; Garishvili, A.; Garishvili, I.; Glenn, A.; Gong, H.; Gong, X.; Gonin, M.; Gosset, J.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Guo, L.; Gustafsson, H. -Å.; Hachiya, T.; Hadj Henni, A.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Han, R.; Hanks, J.; Hartouni, E. P.; Haruna, K.; Hashimoto, K.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Hollis, R. S.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hori, Y.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Iinuma, H.; Ikeda, Y.; Imai, K.; Imrek, J.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Ivanishchev, D.; Jacak, B. V.; Javani, M.; Jia, J.; Jiang, X.; Jin, J.; Johnson, B. M.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kaneti, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kikuchi, J.; Kim, B. I.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E. -J.; Kim, H. J.; Kim, K. -B.; Kim, S. H.; Kim, Y. -J.; Kim, Y. K.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Klatsky, J.; Klay, J.; Klein-Boesing, C.; Kleinjan, D.; Kline, P.; Kochenda, L.; Komatsu, Y.; Komkov, B.; Konno, M.; Koster, J.; Kotchetkov, D.; Kotov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Krizek, F.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Layton, D.; Lebedev, A.; Lee, B.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Lee, S. R.; Lee, T.; Leitch, M. J.; Leite, M. A. L.; Leitgab, M.; Lenzi, B.; Lewis, B.; Li, X.; Liebing, P.; Lim, S. H.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Makek, M.; Malakhov, A.; Malik, M. D.; Manion, A.; Manko, V. I.; Mannel, E.; Mao, Y.; Mašek, L.; Masui, H.; Masumoto, S.; Matathias, F.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Means, N.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, D. K.; Mishra, M.; Mitchell, J. T.; Miyachi, Y.; Miyasaka, S.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Motschwiller, S.; Moukhanova, T. V.; Mukhopadhyay, D.; Murakami, T.; Murata, J.; Nagae, T.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nattrass, C.; Nederlof, A.; Newby, J.; Nguyen, M.; Nihashi, M.; Niida, T.; Nouicer, R.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, B. H.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Patel, L.; Pei, H.; Peng, J. -C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.

    2015-02-24

    Measurements of bottomonium production in heavy-ion and p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The inclusive yield of the three Υ states, Υ(1S + 2S + 3S), was measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au+Au and p+p collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV. The Υ(1S + 2S + 3S) → e⁺e⁻ differential cross section at midrapidity was found to be Beedσ/dy = 108 ± 38 (stat) ± 15 (syst) ± 11 (luminosity) pb in p+p collisions. The nuclear modification factor in the 30% most central Au+Au collisions indicates a suppression of the total Υ state yield relative to the extrapolation from p+p collision data. Thus, the suppression is consistent with measurements at higher energies by the CMS experiment at the Large Hadron Collider.

  1. Measurement of Υ(1S + 2S +3S) production in p + p and Au + Au collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV

    DOE PAGESBeta

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Bataineh, H.; Al-Ta'ani, H.; Alexander, J.; Angerami, A.; et al

    2015-02-24

    Measurements of bottomonium production in heavy-ion and p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The inclusive yield of the three Υ states, Υ(1S + 2S + 3S), was measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au+Au and p+p collisions at \\(\\sqrt{s_{\\mathrm{NN}}}=200\\) GeV. The Υ(1S + 2S + 3S) → e⁺e⁻ differential cross section at midrapidity was found to be Beedσ/dy = 108 ± 38 (stat) ± 15 (syst) ± 11 (luminosity) pb in p+p collisions. The nuclear modification factor in the 30% most central Au+Au collisions indicates a suppression of themore » total Υ state yield relative to the extrapolation from p+p collision data. Thus, the suppression is consistent with measurements at higher energies by the CMS experiment at the Large Hadron Collider.« less

  2. Energy dependence of Kπ, pπ and Kp fluctuations in Au+Au collisions from √sNN=7.7 to 200 GeV

    DOE PAGESBeta

    Adamczyk, L.

    2015-08-07

    A search for the quantum chromodynamics (QCD) critical point was performed by the STAR experiment at the Relativistic Heavy Ion Collider, using dynamical fluctuations of unlike particle pairs. Heavy ion collisions were studied over a large range of collision energies with homogeneous acceptance and excellent particle identification, covering a significant range in the QCD phase diagram where a critical point may be located. Dynamical Kπ, pπ, and Kp fluctuations as measured by the STAR experiment in central 0–5% Au+Au collisions from center-of-mass collision energies √sNN=7.7 to 200 GeV are presented. The observable νdyn was used to quantify the magnitude ofmore » the dynamical fluctuations in event-by-event measurements of the Kπ, pπ, and Kp pairs. The energy dependences of these fluctuations from central 0–5% Au+Au collisions all demonstrate a smooth evolution with collision energy.« less

  3. Azimuthal Anisotropy at Intermediate Rapidity in √SNN = 200 GeV Au-Au Collisions in PHENIX at RHIC-BNL

    NASA Astrophysics Data System (ADS)

    Norman, Benjamin

    2005-04-01

    In mid-central heavy ion collisions, the nuclear overlap region is almond shaped. This spatial anisotropy leads to a momentum space anisotropy, which has symmetry about the plane defined by the beam axis and the impact parameter. This reaction plane (or event plane) can be determined in experiment using the final particle azimuthal distribution. The reaction plane resolution depends on particle multiplicity, azimuthal angle resolution, azimuthal hermeticity, and the amount of actual asymmetry that exists in the collision. We will present the effect of these factors on the resolution of the reaction plane for Au-Au collisions in general and more specifically for the pad planes of the PHENIX Multiplicity Vertex Detector (MVD). These pad planes are in the pseudorapidity range 1.8 < |eta| < 2.6 on either side of the vertex region for which PHOBOS data (nucl-ex/0403025) suggest a v2 of about 4 percent for mid-central Au-Au collisions at √SNN of 200 GeV.

  4. Charge-asymmetry dependence of kaon elliptic flow in Au +Au collisions at √{sNN} = 27 GeV from STAR

    NASA Astrophysics Data System (ADS)

    Cabrera, Keenan; STAR Collaboration

    2015-10-01

    Theory predicts that a chiral magnetic wave (CMW) at finite baryon density can induce a charge-asymmetry dependence of elliptic flow (v2) of particles produced in heavy-ion collisions. In the case of pions, STAR has observed that v2 (π-) -v2 (π+) exhibits a linear dependence on charge asymmetry with a positive slope in Au +Au collisions from 27 to 200 GeV. This is consistent with the CMW picture. At lower collision energies, it was found that the charge-asymmetry integrated v2 for negative pions is higher while for kaons, the positive charge is favored. Therefore, an observation of the same positive linear dependence of kaon v2 difference on charge asymmetry will provide a further test on the CMW predictions in heavy-ion collisions. In this work, we will present the status of our kaon elliptic flow measurements as a function of charge asymmetry for Au +Au collisions at √{sNN} = 27 GeV. For the STAR Collaboration.

  5. Energy-transfer from ultra-small Au nanoclusters to Er³⁺ ions: a short-range mechanism.

    PubMed

    Cesca, Tiziana; Kalinic, Boris; Michieli, Niccolò; Maurizio, Chiara; Scian, Carlo; Devaraju, Gurram; Battaglin, Giancarlo; Mazzoldi, Paolo; Mattei, Giovanni

    2014-08-01

    Sub-nanometric Au nanoclusters are known to act as very efficient sensitizers for the luminescent emission of Er(3+) ions in silica through a non-resonant broad-band energy-transfer mechanism. In the present work the energy-transfer process is investigated in detail by room temperature photoluminescence characterization of Er and Au co-implanted silica systems in which a different degree of coupling between Er(3+) ions and Au nanoclusters is obtained. The results allow us to definitely demonstrate the short-range nature of the interaction in agreement with non-radiative energy-transfer mechanisms. Moreover, an upper limit to the interaction length is also set by the Au-Au intercluster semi-distance which is smaller than 2.4 nm in the present case. PMID:24935519

  6. Simulation of Electric Field in Semi Insulating Au/CdTe/Au Detector under Flux

    SciTech Connect

    Franc, J.; James, R.; Grill, R.; Kubat, J.; Belas, E.; Hoschl, P.; Moravec, P.; Praus, P.

    2009-08-02

    We report our simulations on the profile of the electric field in semi insulating CdTe and CdZnTe with Au contacts under radiation flux. The type of the space charge and electric field distribution in the Au/CdTe/Au structure is at high fluxes result of a combined influence of charge formed due to band bending at the electrodes and from photo generated carriers, which are trapped at deep levels. Simultaneous solution of drift-diffusion and Poisson equations is used for the calculation. We show, that the space charge originating from trapped photo-carriers starts to dominate at fluxes 10{sup 15}-10{sup 16}cm{sup -2}s{sup -1}, when the influence of contacts starts to be negligible.

  7. Controlled protein embedment onto Au/Ag core-shell nanoparticles for immuno-labeling of nanosilver surface.

    PubMed

    Lee, In Hwan; Lee, Jeong Min; Jung, Yongwon

    2014-05-28

    Difficulties in stable conjugation of biomolecules to nanosilver surfaces have severely limited the use of silver nanostructures in biological applications. Here, we report a facile antibody conjugation onto gold/silver (Au/Ag) core-shell nanoparticles by stable and uniform embedment of an antibody binding protein, protein G, in silver nanoshells. A rigid helical peptide linker with a terminal cysteine residue was fused to protein G. A mixture of the peptide-fused protein G and space-filling free peptide was reacted with gold nanoparticles (AuNPs) to form a protein G-linked peptide layer on the particle surface. Uniform silver nanoshells were successfully formed on these protein G-AuNPs, while stably embedding protein G-linked peptide layers. Protein G specifically targets the Fc region of an antibody and thus affords properly orientated antibodies on the particle surface. Compared to Au nanoparticles of similar size with randomly adsorbed antibodies, the present immuno-labeled Au/Ag core-shell nanoparticles offered nearly 10-fold higher sensitivities for naked-eye detection of surface bound antigens. In addition, small dye molecules that were bonded to the peptide layer on Au nanoparticles exhibited highly enhanced surface-enhanced Raman scattering (SERS) signals upon Ag shell formation. The present strategy provides a simple but efficient way to conjugate antibodies to nanosilver surfaces, which will greatly facilitate wider use of the superior optical properties of silver nanostructures in biological applications. PMID:24801432

  8. Saturation of azimuthal anisotropy in Au + Au collisions at (square root)s(NN) = 62-200 GeV.

    PubMed

    Adler, S S; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Jamel, A; Alexander, J; Amirikas, R; Aoki, K; Aphecetche, L; Armendariz, R; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, B; Azmoun, R; Babintsev, V; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bauer, F; Bazilevsky, A; Belikov, S; Bennett, R; Berdnikov, Y; Bhagavatula, S; Bjorndal, M T; Boissevain, J G; Borel, H; Borenstein, S; Boyle, K; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Campbell, S; Chai, J-S; Chand, P; Chang, W C; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Choi, J; Choudhury, R K; Chujo, T; Cianciolo, V; Cleven, C R; Cobigo, Y; Cole, B A; Comets, M P; Constantin, P; Csanád, M; Csörgo, T; d'Enterria, D; Dahms, T; Das, K; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Devismes, A; Dietzsch, O; Dion, A; Drachenberg, J L; Drapier, O; Drees, A; Drees, K A; Dubey, A K; du Rietz, R; Durum, A; Dutta, D; Dzhordzhadze, V; Efremenko, Y V; Egdemir, J; El Chenawi, K; Enokizono, A; En'yo, H; Espagnon, B; Esumi, S; Ewell, L; Fields, D E; Fleuret, F; Fokin, S L; Forestier, B; Fox, B D; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Fung, S-Y; Gadrat, S; Garpman, S; Gastineau, F; Germain, M; Ghosh, T K; Glenn, A; Gogiberidze, G; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Perdekamp, M Grosse; Gunji, T; Guryn, W; Gustafsson, H-A; Hachiya, T; Henni, A Hadj; Haggerty, J S; Hagiwara, M N; Hamagaki, H; Hansen, A G; Harada, H; Hartouni, E P; Haruna, K; Harvey, M; Haslum, E; Hasuko, K; Hayano, R; Hayashi, N; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hibino, M; Hiejima, H; Hill, J C; Hobbs, R; Holmes, M; Holzmann, W; Homma, K; Hong, B; Hoover, A; Horaguchi, T; Hur, H M; Ichihara, T; Ikonnikov, V V; Imai, K; Inaba, M; Isenhower, D; Isenhower, L; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Jacak, B V; Jang, W Y; Jeong, Y; Jia, J; Jin, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kajihara, F; Kametani, S; Kamihara, N; Kaneta, M; Kang, J H; Kapoor, S S; Katou, K; Kawagishi, T; Kazantsev, A V; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D H; Kim, D J; Kim, D W; Kim, E; Kim, G-B; Kim, H J; Kim, Y-S; Kinney, E; Kinnison, W W; Kiss, A; Kistenev, E; Kiyomichi, A; Kiyoyama, K; Klein-Boesing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Komkov, B; Konno, M; Kopytine, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kuberg, C H; Kunde, G J; Kurihara, N; Kurita, K; Kuroki, Y; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Ladygin, V; Lajoie, J G; Le Bornec, Y; Lebedev, A; Leckey, S; Lee, D M; Lee, M K; Lee, S; Leitch, M J; Leite, M A L; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Liu, Y; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mao, Y; Martinez, G; Marx, M D; Masui, H; Matathias, F; Matsumoto, T; McCain, M C; McGaughey, P L; Melnikov, E; Messer, F; Miake, Y; Milan, J; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Moukhanova, T V; Mühlbacher, F; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagata, Y; Nagle, J L; Naglis, M; Nakamura, T; Nandi, B K; Nara, M; Newby, J; Nguyen, M; Nilsson, P; Norman, B; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, H; Okada, K; Omiwade, O O; Ono, M; Onuchin, V; Oskarsson, A; Otterlund, I; Oyama, K; Ozawa, K; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Park, W J; Parmar, A; Pate, S F; Pei, H; Peitzmann, T; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Plasil, F; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Rykov, V L; Ryu, S S; Sadler, M E; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakai, M; Sakai, S; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Semenov, V; Seto, R; Sharma, D; Shaw, M R; Shea, T K; Shein, I; Shibata, T-A; Shigaki, K; Shiina, T; Shimomura, M; Shohjoh, T; Shoji, K; Sickles, A; Silva, C L; Silvermyr, D; Sim, K S; Simon-Gillo, J; Singh, C P; Singh, V; Sivertz, M; Skutnik, S; Smith, W C; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Suire, C; Sullivan, J P; Sziklai, J; Tabaru, T; Takagi, S; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Taranenko, A; Tarján, P; Tepe, J D; Thomas, T L; Togawa, M; Tojo, J; Torii, H; Towell, R S; Tram, V-N; Tserruya, I; Tsuchimoto, Y; Tsuruoka, H; Tuli, S K; Tydesjö, H; Tyurin, N; Valle, H; van Hecke, H W; Velkovska, J; Velkovsky, M; Vertesi, R; Veszprémi, V; Villatte, L; Vinogradov, A A; Volkov, M A; Vznuzdaev, E; Wagner, M; Wang, X R; Watanabe, Y; Wessels, J; White, S N; Willis, N; Winter, D; Wohn, F K; Woody, C L; Wysocki, M; Xie, W; Yang, Y; Yanovich, A; Yokkaichi, S; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zaudkte, O; Zhang, C; Zhou, S; Zhou, S J; Zimányi, J; Zolin, L

    2005-06-17

    New measurements are presented for charged hadron azimuthal correlations at midrapidity in Au+Au collisions at (square root)s(NN) = 62.4 and 200 GeV. They are compared to earlier measurements obtained at (square root)s(NN) = 130 GeV and in Pb + Pb collisions at (square root)s(NN) = 17.2 GeV. Sizeable anisotropies are observed with centrality and transverse momentum (pT) dependence characteristic of elliptic flow (upsilon2). For a broad range of centralities, the observed magnitudes and trends of the differential anisotropy, upsilon2(pT), change very little over the collision energy range (square root)s(NN) = 62-200 GeV, indicating saturation of the excitation function for upsilon2 at these energies. Such a saturation may be indicative of the dominance of a very soft equation of state for (square root)s(NN) approximately 60-200 GeV. PMID:16090463

  9. Dielectron mass spectra from Au+Au collisions at √[s(NN)]=200  GeV.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Barnovska, Z; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Grosnick, D; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hajkova, O; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Korsch, W; Kotchenda, L; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lima, L M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Munhoz, M G; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Oliveira, R A N; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Plyku, D; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandacz, A; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; deSouza, U G; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Suaide, A A P; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szanto de Toledo, A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-07-11

    We report the STAR measurements of dielectron (e(+)e(-)) production at midrapidity (|y(ee)|<1) in Au+Au collisions at √[s(NN)]=200  GeV. The measurements are evaluated in different invariant mass regions with a focus on 0.30-0.76 (ρ-like), 0.76-0.80 (ω-like), and 0.98-1.05 (ϕ-like)   GeV/c(2). The spectrum in the ω-like and ϕ-like regions can be well described by the hadronic cocktail simulation. In the ρ-like region, however, the vacuum ρ spectral function cannot describe the shape of the dielectron excess. In this range, an enhancement of 1.77±0.11(stat)±0.24(syst)±0.33(cocktail) is determined with respect to the hadronic cocktail simulation that excludes the ρ meson. The excess yield in the ρ-like region increases with the number of collision participants faster than the ω and ϕ yields. Theoretical models with broadened ρ contributions through interactions with constituents in the hot QCD medium provide a consistent description of the dilepton mass spectra for the measurement presented here and the earlier data at the Super Proton Synchrotron energies. PMID:25062167

  10. Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au+Au Collisions at RHIC.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Aparin, A; Arkhipkin, D; Aschenauer, E C; Attri, A; Averichev, G S; Bai, X; Bairathi, V; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Bouchet, J; Brandenburg, J D; Brandin, A V; Bunzarov, I; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Campbell, J M; Cebra, D; Chakaberia, I; Chaloupka, P; Chang, Z; Chatterjee, A; Chattopadhyay, S; Chen, J H; Chen, X; Cheng, J; Cherney, M; Christie, W; Contin, G; Crawford, H J; Das, S; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; di Ruzza, B; Didenko, L; Dilks, C; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Eppley, G; Esha, R; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Federic, P; Fedorisin, J; Feng, Z; Filip, P; Fisyak, Y; Flores, C E; Fulek, L; Gagliardi, C A; Garand, D; Geurts, F; Gibson, A; Girard, M; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, S; Gupta, A; Guryn, W; Hamad, A I; Hamed, A; Haque, R; Harris, J W; He, L; Heppelmann, S; Heppelmann, S; Hirsch, A; Hoffmann, G W; Horvat, S; Huang, T; Huang, X; Huang, B; Huang, H Z; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Jentsch, A; Jia, J; Jiang, K; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Khan, Z H; Kikoła, D P; Kisel, I; Kisiel, A; Kochenda, L; Koetke, D D; Kosarzewski, L K; Kraishan, A F; Kravtsov, P; Krueger, K; Kumar, L; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Li, X; Li, C; Li, X; Li, Y; Li, W; Lin, T; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, R; Ma, G L; Ma, Y G; Ma, L; Magdy, N; Majka, R; Manion, A; Margetis, S; Markert, C; Matis, H S; McDonald, D; McKinzie, S; Meehan, K; Mei, J C; Minaev, N G; Mioduszewski, S; Mishra, D; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nigmatkulov, G; Niida, T; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Okorokov, V A; Olvitt, D; Page, B S; Pak, R; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlik, B; Pei, H; Perkins, C; Pile, P; Pluta, J; Poniatowska, K; Porter, J; Posik, M; Poskanzer, A M; Pruthi, N K; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, S; Raniwala, R; Ray, R L; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, A; Sharma, B; Sharma, M K; Shen, W Q; Shi, Z; Shi, S S; Shou, Q Y; Sichtermann, E P; Sikora, R; Simko, M; Singha, S; Skoby, M J; Smirnov, N; Smirnov, D; Solyst, W; Song, L; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stepanov, M; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Summa, B; Sun, Z; Sun, X M; Sun, Y; Surrow, B; Svirida, D N; Tang, Z; Tang, A H; Tarnowsky, T; Tawfik, A; Thäder, J; Thomas, J H; Timmins, A R; Tlusty, D; Todoroki, T; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Tripathy, S K; Tsai, O D; Ullrich, T; Underwood, D G; Upsal, I; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Varma, R; Vasiliev, A N; Vertesi, R; Videbæk, F; Vokal, S; Voloshin, S A; Vossen, A; Wang, F; Wang, G; Wang, J S; Wang, H; Wang, Y; Wang, Y; Webb, G; Webb, J C; Wen, L; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y; Xiao, Z G; Xie, W; Xie, G; Xin, K; Xu, Y F; Xu, Q H; Xu, N; Xu, H; Xu, Z; Xu, J; Yang, S; Yang, Y; Yang, Y; Yang, C; Yang, Y; Yang, Q; Ye, Z; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zbroszczyk, H; Zha, W; Zhang, X P; Zhang, Y; Zhang, J; Zhang, J; Zhang, S; Zhang, S; Zhang, Z; Zhang, J B; Zhao, J; Zhong, C; Zhou, L; Zhu, X; Zoulkarneeva, Y; Zyzak, M

    2016-03-18

    We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au+Au collisions for energies ranging from sqrt[s_{NN}]=7.7 to 200 GeV. The third harmonic v_{3}^{2}{2}=⟨cos3(ϕ_{1}-ϕ_{2})⟩, where ϕ_{1}-ϕ_{2} is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δη=η_{1}-η_{2}. Nonzero v_{3}^{2}{2} is directly related to the previously observed large-Δη narrow-Δϕ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v_{3}^{2}{2} persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v_{3}^{2}{2} is consistent with zero. When scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v_{3}^{2}{2} for central collisions shows a minimum near sqrt[s_{NN}]=20  GeV. PMID:27035295

  11. Beam Energy Dependence of Moments of the Net-Charge Multiplicity Distributions in Au +Au Collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Balewski, J.; Banerjee, A.; Barnovska, Z.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Grosnick, D.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Hays-Wehle, J. P.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Korsch, W.; Kotchenda, L.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Leight, W.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Munhoz, M. G.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Peterson, A.; Pile, P.; Planinic, M.; Pluta, J.; Plyku, D.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Vossen, A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2014-08-01

    We report the first measurements of the moments—mean (M), variance (σ2), skewness (S), and kurtosis (κ)—of the net-charge multiplicity distributions at midrapidity in Au +Au collisions at seven energies, ranging from √sNN =7.7 to 200 GeV, as a part of the Beam Energy Scan program at RHIC. The moments are related to the thermodynamic susceptibilities of net charge, and are sensitive to the location of the QCD critical point. We compare the products of the moments, σ2/M, Sσ, and κσ2, with the expectations from Poisson and negative binomial distributions (NBDs). The Sσ values deviate from the Poisson baseline and are close to the NBD baseline, while the κσ2 values tend to lie between the two. Within the present uncertainties, our data do not show nonmonotonic behavior as a function of collision energy. These measurements provide a valuable tool to extract the freeze-out parameters in heavy-ion collisions by comparing with theoretical models.

  12. Beam energy dependence of moments of the net-charge multiplicity distributions in Au+Au collisions at RHIC.

    PubMed

    Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Balewski, J; Banerjee, A; Barnovska, Z; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Corliss, R; Cramer, J G; Crawford, H J; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Grosnick, D; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hajkova, O; Hamed, A; Han, L-X; Haque, R; Harris, J W; Hays-Wehle, J P; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Korsch, W; Kotchenda, L; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Leight, W; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lima, L M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Munhoz, M G; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Oliveira, R A N; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Peterson, A; Pile, P; Planinic, M; Pluta, J; Plyku, D; Poljak, N; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandacz, A; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; deSouza, U G; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Suaide, A A P; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szanto de Toledo, A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Walker, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M

    2014-08-29

    We report the first measurements of the moments--mean (M), variance (σ(2)), skewness (S), and kurtosis (κ)--of the net-charge multiplicity distributions at midrapidity in Au+Au collisions at seven energies, ranging from sqrt[sNN]=7.7 to 200 GeV, as a part of the Beam Energy Scan program at RHIC. The moments are related to the thermodynamic susceptibilities of net charge, and are sensitive to the location of the QCD critical point. We compare the products of the moments, σ(2)/M, Sσ, and κσ(2), with the expectations from Poisson and negative binomial distributions (NBDs). The Sσ values deviate from the Poisson baseline and are close to the NBD baseline, while the κσ(2) values tend to lie between the two. Within the present uncertainties, our data do not show nonmonotonic behavior as a function of collision energy. These measurements provide a valuable tool to extract the freeze-out parameters in heavy-ion collisions by comparing with theoretical models. PMID:25215979

  13. Nanoscale electrical characteristics of metal (Au, Pd)-graphene-metal (Cu) contacts

    NASA Astrophysics Data System (ADS)

    Ruffino, F.; Meli, G.; Grimaldi, M. G.

    2016-01-01

    Free-standing graphene presents exceptional physical properties (as a high carrier mobility) making it the ideal candidate for the next generation nanoelectronics. However, when graphene layers are inserted in real electronics devices, metal contacting is required. The metal-graphene interaction significantly affects the graphene electrical properties, drastically changing its behavior with respect to the free-standing configuration. So, this work presents an experimental study on the nanoscale electric characteristics of metal/graphene/metal contacts. In particular, starting from single-layer graphene grown on Cu foil we deposited on the graphene surface two different metal films (Au or Pd) and the Au/graphene/Cu and Pd/graphene/Cu current-voltage characteristics are acquired, on the nanometric scale, by the conductive atomic force microscopy. Both systems presented a current voltage rectifying behavior. However, the Au/graphene/Cu system conducts significantly at negative applied bias (graphene behaves as a p-type semiconductor in a meta/semiconductor contact), while in the Pd/graphene/Cu at positive applied bias (graphene behaves as a n-type semiconductor in a metal/semiconductor contact). This difference is discussed on the basis of the band energy diagram at the metal/graphene interface and the modification of the graphene Fermi level due to the Au/graphene or Pd/graphene interaction.

  14. Diffusion-induced grain boundary migration during ion beam mixing of Au/Cu bilayers

    SciTech Connect

    Alexander, D.E.; Baldo, P.M.; Rehn, L.E.

    1992-09-01

    Experiments were performed to evaluate the effect of 1.5 MeV Kr irradiation on diffusion-induced grain boundary migration (DIGM) in Au/Cu bilayers in the temperature range of 300{le}T{le}050K. The experimental results were consistent with DIGM occurring in bilayers both during irradiation and during annealing treatments. Rutherford backscattering spectrometry showed a nearly uniform distribution of Cu present through the entire thickness of appropriately prepared polycrystalline Au films irradiated or annealed at temperatures {ge}400K. No parallel effect was seen in similarly treated single-crystal films. In each polycrystalline sample studied, irradiation resulted in greater amounts of Cu present uniformly in the Au compared to annealing-only. The magnitudes of measured Cu compositions were substantially greater than that expected solely from grain boundary diffusion. A simple analysis of the process indicated that ion irradiation affects DIGM by increasing the composition of Cu present in alloyed zones and/or by increasing the grain boundary velocity in the Au.

  15. Unconventional but tunable phase transition above the percolation threshold by two-layer conduction in electroless-deposited Au nanofeatures on silicon substrate

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Hoon; Shin, Muncheol; Hwang, Seongpil; Jang, Jae-Won

    2015-12-01

    Previous research has shown that disorder, dislocation, and carrier concentration are the main factors impacting transitions in the traditional metal-insulator transition (MIT) and metal-semiconductor transition (MST). In this study, it is demonstrated that a non-traditional metal-semiconductor transition governed by two-layer conduction is possible by tuning the conducting channel of one layer of the two-layer conduction system. By means of the electroless deposition method we produced Au nanofeatures (AuNFs) on p-type silicon (p-Si) as the two-layer conduction system, controlling AuNF coverage (Au%) below and above the percolation threshold (p c). Even when the AuNF coverage percentage is larger than p c, the resistivities of the AuNFs on p-Si show MST as the temperature increases. To demonstrate this finding, we present a conduction model based upon two predominant parallel conductions by AuNFs and p-Si in the present paper. In the results, we show how the temperature of the MST (T MST) is tuned from 145 to 232 K as Au% is changed from 82.7 to 54.3%.

  16. Unconventional but tunable phase transition above the percolation threshold by two-layer conduction in electroless-deposited Au nanofeatures on silicon substrate

    NASA Astrophysics Data System (ADS)

    Lee, Seung-Hoon; Hwang, Seongpil; Jang, Jaw-Won

    Previous research has shown that disorder, dislocation, and carrier concentration are the main factors impacting transitions in the traditional metal-insulator transition (MIT) and metal-semiconductor transition (MST). In this study, it is demonstrated that a non-traditional MST governed by two-layer conduction is possible by tuning the conducting channel of one layer of the two-layer conduction system. By means of the electroless deposition method we produced Au nanofeatures (AuNFs) on p-type silicon (p-Si) as the two-layer conduction system, controlling AuNF coverage (Au%) below and above the percolation threshold (pc). Even when the AuNF coverage percentage is larger than pc, the resistivities of the AuNFs on p-Si show MST as the temperature increases. We present a conduction model based upon two predominant parallel conductions by AuNFs and p-Si in the present paper. In the results, we show how the temperature of the MST is tuned from 145 to 232 K as Au% is changed from 82.7 to 54.3%. Supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (no. 2013K1A3A1A32035429 and 2015R1A1A1A05027681).

  17. Admittance of Au/1,4-benzenedithiol/Au single-molecule junctions

    NASA Astrophysics Data System (ADS)

    Yamauchi, Kazumasa; Kurokawa, Shu; Sakai, Akira

    2012-12-01

    Employing the admittance formula for double-barrier junctions [Fu and Dudley, Phys. Rev. Lett. 70, 65 (1993)], we have estimated an ac susceptance (imaginary part of admittance) of Au/1,4-benzenedithiol/Au single-molecule junctions from their current-voltage characteristics. In the MHz regime, we find that the junction susceptance shows a very small (˜0.1 aF) capacitive component that can be entirely masked by a larger electrode capacitance. Direct ac signal transmission measurements up to 1 GHz reveal no molecular signals and confirm the smallness of the molecular capacitance in the MHz regime.

  18. Net charge fluctuations in Au + Au interactions at sqrt[s(NN)]=130 GeV.

    PubMed

    Adcox, K; Adler, S S; Ajitanand, N N; Akiba, Y; Alexander, J; Aphecetche, L; Arai, Y; Aronson, S H; Averbeck, R; Awes, T C; Barish, K N; Barnes, P D; Barrette, J; Bassalleck, B; Bathe, S; Baublis, V; Bazilevsky, A; Belikov, S; Bellaiche, F G; Belyaev, S T; Bennett, M J; Berdnikov, Y; Botelho, S; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J; Butsyk, S; Carey, T A; Chand, P; Chang, J; Chang, W C; Chavez, L L; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choudhury, R K; Christ, T; Chujo, T; Chung, M S; Chung, P; Cianciolo, V; Cole, B A; D'Enterria, D G; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dinesh, B V; Drees, A; Durum, A; Dutta, D; Ebisu, K; Efremenko, Y V; El Chenawi, K; En'yo, H; Esumi, S; Ewell, L; Ferdousi, T; Fields, D E; Fokin, S L; Fraenkel, Z; Franz, A; Frawley, A D; Fung, S-Y; Garpman, S; Ghosh, T K; Glenn, A; Godoi, A L; Goto, Y; Greene, S V; Grosse Perdekamp, M; Gupta, S K; Guryn, W; Gustafsson, H-A; Haggerty, J S; Hamagaki, H; Hansen, A G; Hara, H; Hartouni, E P; Hayano, R; Hayashi, N; He, X; Hemmick, T K; Heuser, J M; Hibino, M; Hill, J C; Ho, D S; Homma, K; Hong, B; Hoover, A; Ichihara, T; Imai, K; Ippolitov, M S; Ishihara, M; Jacak, B V; Jang, W Y; Jia, J; Johnson, B M; Johnson, S C; Joo, K S; Kametani, S; Kang, J H; Kann, M; Kapoor, S S; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D J; Kim, H J; Kim, S Y; Kim, Y G; Kinnison, W W; Kistenev, E; Kiyomichi, A; Klein-Boesing, C; Klinksiek, S; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kotchetkov, D; Kozlov, A; Kroon, P J; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Lauret, J; Lebedev, A; Lee, D M; Leitch, M J; Li, X H; Li, Z; Lim, D J; Liu, M X; Liu, X; Liu, Z; Maguire, C F; Mahon, J; Makdisi, Y I; Manko, V I; Mao, Y; Mark, S K; Markacs, S; Martinez, G; Marx, M D; Masaike, A; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E; Merschmeyer, M; Messer, F; Messer, M; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mühlbacher, F; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagasaka, Y; Nagle, J L; Nakada, Y; Nandi, B K; Newby, J; Nikkinen, L; Nilsson, P; Nishimura, S; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Ono, M; Onuchin, V; Oskarsson, A; Osterman, L; Otterlund, I; Oyama, K; Paffrath, L; Palounek, A P T; Pantuev, V S; Papavassiliou, V; Pate, S F; Peitzmann, T; Petridis, A N; Pinkenburg, C; Pisani, R P; Pitukhin, P; Plasil, F; Pollack, M; Pope, K; Purschke, M L; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Rosati, M; Rose, A A; Ryu, S S; Saito, N; Sakaguchi, A; Sakaguchi, T; Sako, H; Sakuma, T; Samsonov, V; Sangster, T C; Santo, R; Sato, H D; Sato, S; Sawada, S; Schlei, B R; Schutz, Y; Semenov, V; Seto, R; Shea, T K; Shein, I; Shibata, T-A; Shigaki, K; Shiina, T; Shin, Y H; Sibiriak, I G; Silvermyr, D; Sim, K S; Simon-Gillo, J; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sorensen, S; Stankus, P W; Starinsky, N; Steinberg, P; Stenlund, E; Ster, A; Stoll, S P; Sugioka, M; Sugitate, T; Sullivan, J P; Sumi, Y; Sun, Z; Suzuki, M; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Taniguchi, E; Tannenbaum, M J; Thomas, J; Thomas, J H; Thomas, T L; Tian, W; Tojo, J; Torii, H; Towell, R S; Tserruya, I; Tsuruoka, H; Tsvetkov, A A; Tuli, S K; Tydesjö, H; Tyurin, N; Ushiroda, T; van Hecke, H W; Velissaris, C; Velkovska, J; Velkovsky, M; Vinogradov, A A; Volkov, M A; Vorobyov, A; Vznuzdaev, E; Wang, H; Watanabe, Y; White, S N; Witzig, C; Wohn, F K; Woody, C L; Xie, W; Yagi, K; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, Z; Zhou, S

    2002-08-19

    Data from Au + Au interactions at sqrt[s(NN)]=130 GeV, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays. PMID:12190459

  19. Domain wall dynamics in a spin-reorientation transition system Au/Co/Au

    SciTech Connect

    Roy, Sujoy; Seu, Keoki; Turner, Joshua J.; Park, Sungkyun; Kevan, Steve; Falco, Charles M.

    2009-05-14

    We report measurements of domain wall dynamics in an ultrathin Au/Co/Au system that exhibits a spin reorientation phase transition as a function of temperature.The domain walls exhibit cooperative motion throughout the temperature range of 150 - 300 K. The decay times were found to exhibit a maximum at the transition temperature. The slowdown has been explained as due to formation of a double well in the energy landscape by the different competing interactions. Our results show that the complex, slow dynamics can provide a more fundamental understanding of magnetic phase transitions.

  20. Measuring away-side jet modifications in Au+Au collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Jiang, Kun; STAR Collaboration

    2015-08-01

    We report measurements of jet correlations in Au+Au collisions at = 200 GeV by the STAR experiment. In this analysis we devise a novel method to subtract flow background using data itself. The correlation width is studied as a function of centrality and associated particle pTT. The width is found to increase with centrality at modest to high associated particle pTT. The increase can arise from jet modification by medium and/or event averaging of away-side jets deflected by medium flow. The discrimination of the physics mechanisms requires further study by three-particle correlations.

  1. Two-Particle Interferometry of 200 GeV Au+Au Collisions at PHENIX

    SciTech Connect

    Heffner, M

    2004-04-19

    The PHENIX experiment has measured pion-pion, kaon-kaon, and proton-proton correlations in Au+Au collisions at {radical}S{sub NN} = 200GeV. The correlations are fit to extract radii using both the Bowler Coulomb correction and full calculation of the two-particle wave function. The resulting radii are similar for all three species and decrease with increasing k{sub t} as expected for collective flow. The R{sub out} and R{sub side} radii are approximately equal indicating a short emission duration.

  2. Onset of nuclear vaporization in [sup 197]Au+[sup 197]Au collisions

    SciTech Connect

    Tsang, M.B.; Hsi, W.C.; Lynch, W.G.; Bowman, D.R.; Gelbke, C.K.; Lisa, M.A.; Peaslee, G.F. ); Kunde, G.J.; Begemann-Blaich, M.L.; Hofmann, T.; Hubele, J.; Kempter, J.; Kreutz, P.; Kunze, W.D.; Lindenstruth, V.; Lynen, U.; Mang, M.; Mueller, W.F.J.; Neumann, M.; Ocker, B.; Ogilvie, C.A.; Pochodzalla, J.; Rosenberger, F.; Sann, H.; Schuettauf, A.; Serfling, V.; Stroth, J.; Trautmann, W.; Tucholski, A.; Woerner, A.; Zude, E.; Zwieglinski, B. ); Aiello, S.; Imme, G.; Pappalardo, V.; Raciti, G. ); Charity, R.J.; Sobotka, L.G. ); Iori, I.; Moroni, A.; Scardoni, R.; Ferr

    1993-09-06

    Multifragmentation has been measured for [sup 197]Au+[sup 197]Au collisions at [ital E]/[ital A]=100, 250, and 400 MeV. The mean fragment multiplicity increases monotonically with the charged particle multiplicity at [ital E]/[ital A]=100 MeV, but decreases for central collisions with incident energy, consistent with the onset of nuclear vaporization. Molecular dynamics calculations follow some trends but underpredict the observed fragment multiplicities. Including the statistical decay of excited residues improves the agreement for peripheral collisions but worsens it for central collisions.

  3. Relativistic multireference many-body perturbation theory calculations on Au64+ - Au69+ ions

    SciTech Connect

    Vilkas, M J; Ishikawa, Y; Trabert, E

    2006-03-31

    Many-body perturbation theory (MBPT) calculations are an adequate tool for the description of the structure of highly charged multi-electron ions and for the analysis of their spectra. They demonstrate this by way of a re-investigation of n=3, {Delta}n=0 transitions in the EUV spectra of Na-, Mg-, Al-like, and Si-like ions of Au that have been obtained previously by heavy-ion accelerator based beam-foil spectroscopy. They discuss the evidence and propose several revisions on the basis of the multi-reference many-body perturbation theory calculations of Ne- through P-like ions of Au.

  4. Initial-state geometry and fluctuations in Au + Au, Cu + Au, and U + U collisions at energies available at the BNL Relativistic Heavy Ion Collider

    NASA Astrophysics Data System (ADS)

    Schenke, Björn; Tribedy, Prithwish; Venugopalan, Raju

    2014-06-01

    We study within the IP-Glasma and two-component MC-Glauber models the effects of initial-state geometry and fluctuations on multiplicities and eccentricities for several collision species at the Relativistic Heavy Ion Collider (RHIC). These include copper-gold (Cu + Au), gold-gold (Au + Au), and uranium-uranium (U + U) collisions. The multiplicity densities per participant pair are very similar in all systems studied. Ellipticities vary strongly between collision systems, most significantly for central collisions, while fluctuation driven odd moments vary little between systems. Event-by-event distributions of eccentricities in mid-central collisions are wider in Cu + Au relative to Au + Au and U + U systems. An anticorrelation between multiplicity and eccentricity is observed in ultracentral U + U collisions which is weaker in the IP-Glasma model than the two-component MC-Glauber model. In ultracentral Au + Au collisions the two models predict opposite signs for the slope of this correlation. Measurements of elliptic flow as a function of multiplicity in such central events can therefore be used to discriminate between models with qualitatively different particle production mechanisms.

  5. Bridging gold in electron-deficient Al2Au(n)(0/-) and BAlAu(n)(0/-) (n = 1-3) clusters.

    PubMed

    Yao, Wen-Zhi; Liu, Bing-Tao; Lu, Zhang-Hui; Li, Si-Dian

    2013-06-20

    The geometrical and electronic structures of the electron-deficient dialuminum aurides Al2Aun(0/-) and hybrid boron-aluminum aurides BAlAun(0/-) (n = 1-3) are systematically investigated based on the density and wave function theories. Ab initio theoretical evidence strongly suggests that bridging gold atoms exist in the ground states of C2v Al2Au(-) ((3)B1), C2v Al2Au ((2)B1), C2v Al2Au2(-) ((2)A1), C2v Al2Au2 ((1)A1), Cs Al2Au3(-) ((1)A'), and D3h Al2Au3 ((2)A1), which prove to possess an Al-Au-Al τ bond. For BAlAun(0/-) (n = 1-3) mixed clusters, bridging B-Au-Al units only exist in Cs BAlAu3(-) ((1)A') and Cs BAlAu3 ((2)A'), whereas Cs BAlAu(-) ((3)A''), Cs BAlAu ((2)A''), Cs BAlAu2(-) ((2)A'), and Cs BAlAu2 ((1)A') do not possess a bridging gold, as demonstrated by the fact that B-Al and B-Au exhibit significantly stronger electronic interaction than Al-Au in the same clusters. Orbital analyses indicate that Au 6s contributes approximately 98%-99% to the Au-based orbital in these Al-Au-Al/B-Au-Al interactions, whereas Au 5d contributes 1%-2%. The adiabatic and vertical detachment energies of Al2Aun(-) (n = 1-3) are calculated to facilitate future experimental characterizations. The results obtained in this work establish an interesting τ bonding model (Al-Au-Al/B-Au-Al) for electron-deficient systems in which Au 6s plays a major factor. PMID:23718624

  6. EuAu3Al2: Crystal and Electronic Structures and Spectroscopic, Magnetic, and Magnetocaloric Properties.

    PubMed

    Schmiegel, Jan-Patrick; Block, Theresa; Gerke, Birgit; Fickenscher, Thomas; Touzani, Rachid St; Fokwa, Boniface P T; Janka, Oliver

    2016-09-01

    The intermetallic compound EuAu3Al2 has been prepared by reaction of the elements in tantalum ampules. The structure was refined from single-crystal data, indicating that the title compound crystallizes in the orthorhombic crystal system (a = 1310.36(4), b = 547.87(1), c = 681.26(2) pm) with space group Pnma (wR2 = 0.0266, 1038 F(2) values, 35 parameters) and is isostructural to SrAu3Al2 (LT-SrZn5 type). Full ordering of the gold and aluminum atoms was observed. Theoretical calculations confirm that the title compound can be described as a polar intermetallic phase containing a polyanionic [Au3Al2](δ-) network featuring interconnected strands of edge-sharing [AlAu4] tetrahedra. Magnetic measurements and (151)Eu Mössbauer spectroscopic investigations confirmed the divalent character of the europium atoms. Ferromagnetic ordering below TC = 16.5(1) K was observed. Heat capacity measurements showed a λ-type anomaly at T = 15.7(1) K, in line with the ordering temperature from the susceptibility measurements. The magnetocaloric properties of EuAu3Al2 were determined, and a magnetic entropy of ΔSM = -4.8 J kg(-1) K(-1) for a field change of 0 to 50 kOe was determined. Band structure calculations found that the f-bands of Eu present at the Fermi level of non-spin-polarized calculations are responsible for the ferromagnetic ordering in this phase, whereas COHP chemical bonding coupled with Bader charge analysis confirmed the description of the structure as covalently bonded polyanionic [Au3Al2](δ-) network interacting ionically with Eu(δ+). PMID:27532875

  7. Electrostatic assembles and optical properties of Au CdTe QDs and Ag/Au CdTe QDs

    NASA Astrophysics Data System (ADS)

    Yang, Dongzhi; Wang, Wenxing; Chen, Qifan; Huang, Yuping; Xu, Shukun

    2008-09-01

    Au-CdTe and Ag/Au-CdTe assembles were firstly investigated through the static interaction between positively charged cysteamine-stabilized CdTe quantum dots (QDs) and negatively charged Au or core/shell Ag/Au nano-particles (NCs). The CdTe QDs synthesized in aqueous solution were capped with cysteamine which endowed them positive charges on the surface. Both Au and Ag/Au NCs were prepared through reducing precursors with gallic acid obtained from the hydrolysis of natural plant poly-phenols and favored negative charges on the surface of NCs. The fluorescence spectra of CdTe QDs exhibited strong quenching with the increase of added Au or Ag/Au NCs. Railey resonance scattering spectra of Au or Ag/Au NCs increased firstly and decreased latter with the concentration of CdTe QDs, accompanied with the solution color changing from red to purple and colorless at last. Experimental results on the effects of gallic acid, chloroauric acid tetrahydrate and other reagents demonstrated the static interaction occurred between QDs and NCs. This finding reveals the possibilities to design and control optical process and electromagnetic coupling in hybrid structures.

  8. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  9. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    PubMed Central

    2013-01-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies. PMID:23452438

  10. Activation of molecular oxygen and the nature of the active oxygen species for CO oxidation on oxide supported Au catalysts.

    PubMed

    Widmann, D; Behm, R J

    2014-03-18

    Although highly dispersed Au catalysts with Au nanoparticles (NPs) of a few nanometers in diameter are well-known for their high catalytic activity for several oxidation and reduction reactions already at rather low temperatures for almost 30 years, central aspects of the reaction mechanism are still unresolved. While most studies focused on the active site, the active Au species, and the effect of the support material, the most crucial step during oxidation reactions, the activation of molecular oxygen and the nature of the resulting active oxygen species (Oact), received more attention just recently. This is topic of this Account, which focuses on the formation, location, and nature of the Oact species present on metal oxide supported Au catalysts under typical reaction conditions, at room temperature and above. It is mainly based on quantitative temporal analysis of products (TAP) reactor measurements, which different from most spectroscopic techniques are able to detect and quantify these species even at the extremely low concentrations present under realistic reaction conditions. Different types of pulse experiments were performed, during which the highly dispersed, realistic powder catalysts are exposed to very low amounts of reactants, CO and/or O2, in order to form and reactively remove Oact species and gain information on their formation, nature, and the active site for Oact formation. Our investigations have shown that the active oxygen species for CO oxidation on Au/TiO2 for reaction at 80 °C and higher is a highly stable atomic species, which at 80 °C is formed only at the perimeter of the Au-oxide interface and whose reactive removal by CO is activated, but not its formation. From these findings, it is concluded that surface lattice oxygen represents the Oact species for the CO oxidation. Accordingly, the CO oxidation proceeds via a Au-assisted Mars-van Krevelen mechanism, during which surface lattice oxygen close to the Au NPs is removed by reaction

  11. Structural and electronic properties of AuIr nanoalloys

    NASA Astrophysics Data System (ADS)

    Jiménez-Díaz, Laura M.; Pérez, Luis A.

    2013-01-01

    The lowest-energy structures of binary (AuIr) n , (AuIr3) s , and (Au3Ir) s clusters, with n = 2-20, and s = 5, modeled by the many-body Gupta potential, were obtained by using a genetic-symbiotic algorithm. These structures were further relaxed within the density functional theory to obtain the most stable structures for each composition. Segregation is observed in all the AuIr clusters, where the Ir atoms occupy the cluster core and the Au atoms are situated on the cluster surface. On the other hand, there is experimental evidence that the (AuIr) n nanoalloys could have an enhanced catalytic activity for CO oxidation. In order to study this phenomenon, we also performed first-principles density functional calculations of the CO and O2 adsorption on these bimetallic nanoclusters, considering three different compositions and a fixed cluster size of 20 atoms.

  12. Atomic and molecular adsorption on Au(111)

    SciTech Connect

    Santiago-Rodríguez, Yohaselly; Herron, Jeffrey A.; Curet-Arana, María C.; Mavrikakis, Manos

    2014-09-01

    Periodic self-consistent density functional theory (DFT-GGA) calculations were used to study the adsorption of several atomic species, molecular species and molecular fragments on the Au(111) surface with a coverage of 1/4 monolayer (ML). Binding geometries, binding energies, and diffusion barriers were calculated for 27 species. Furthermore, we calculated the surface deformation energy associated with the binding events. The binding strength for all the analyzed species can be ordered as follows: NH3 < NO < CO < CH3 < HCO < NH2 < COOH < OH < HCOO < CNH2 < H < N < NH < NOH < COH < Cl,< HCO3 < CH2 < CN b HNO < O < F < S < C < CH. Although the atomic species preferred to bind at the three-fold fcc site, no tendency was observed in site preference for the molecular species and fragments. The intramolecular and adsorbate-surface vibrational frequencies were calculated for all the adsorbates on their most energetically stable adsorption site. Most of the theoretical binding energies and frequencies agreed with experimental values reported in the literature. In general, the values obtained with the PW91 functional are more accurate than RPBE in reproducing these experimental binding energies. The energies of the adsorbed species were used to calculate the thermochemical potential energy surfaces for decomposition of CO, NO, N2, NH3 and CH4, oxidation of CO, and hydrogenation of CO, CO2 and NO, giving insight into the thermochemistry of these reactions on gold nanoparticles. These potential energy surfaces demonstrated that: the decomposition of species is not energetically favorable on Au(111); the desorption of NH3, NO and CO are more favorable than their decomposition; the oxidation of CO and hydrogenation of CO and NO on Au(111) to form HCO and HNO, respectively, are also thermodynamically favorable.

  13. Azimuthal correlations of electrons from heavy-flavor decay with hadrons in p+p and Au+Au collisions at {radical}(s{sub NN})=200 GeV

    SciTech Connect

    Adare, A.; Bickley, A. A.; Ellinghaus, F.; Glenn, A.; Kinney, E.; Kiriluk, K.; Linden Levy, L. A.; Nagle, J. L.; Rosen, C. A.; Seele, J.; Wysocki, M.; Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L.; Aidala, C.; Datta, A.

    2011-04-15

    Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled p+p collisions. These measurements indicate that charm and bottom quarks interact with the hot dense matter produced in heavy-ion collisions much more than expected. Here we extend these studies to two-particle correlations where one particle is an electron from the decay of a heavy-flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interactions between heavy quarks and the matter, such as whether the modification of the away-side-jet shape seen in hadron-hadron correlations is present when the trigger particle is from heavy-meson decay and whether the overall level of away-side-jet suppression is consistent. We statistically subtract correlations of electrons arising from background sources from the inclusive electron-hadron correlations and obtain two-particle azimuthal correlations at {radical}(s{sub NN})=200 GeV between electrons from heavy-flavor decay with charged hadrons in p+p and also first results in Au+Au collisions. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to p+p collisions.

  14. Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

    PubMed

    Shabnam, Nisha; Pardha-Saradhi, P

    2013-01-01

    In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant) and Spinacia oleracea (a terrestrial plant) turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD) and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au³⁺ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au³⁺ to Au⁰ which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5-20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m⁻² s⁻¹. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au³⁺ to Au⁰ to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles. PMID:23976990

  15. Surface Plasmon Enhanced Photocatalysis of Au/Pt-decorated TiO2 Nanopillar Arrays

    PubMed Central

    Shuang, Shuang; Lv, Ruitao; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    The low quantum yields and lack of visible light utilization hinder the practical application of TiO2 in high-performance photocatalysis. Herein, we present a design of TiO2 nanopillar arrays (NPAs) decorated with both Au and Pt nanoparticles (NPs) directly synthesized through successive ion layer adsorption and reaction (SILAR) at room temperature. Au/Pt NPs with sizes of ~4 nm are well-dispersed on the TiO2 NPAs as evidenced by electron microscopic analyses. The present design of Au/Pt co-decoration on the TiO2 NPAs shows much higher visible and ultraviolet (UV) light absorption response, which leads to remarkably enhanced photocatalytic activities on both the dye degradation and photoelectrochemical (PEC) performance. Its photocatalytic reaction efficiency is 21 and 13 times higher than that of pure TiO2 sample under UV-vis and visible light, respectively. This great enhancement can be attributed to the synergy of electron-sink function of Pt and surface plasmon resonance (SPR) of Au NPs, which significantly improves charge separation of photoexcited TiO2. Our studies demonstrate that through rational design of composite nanostructures one can harvest visible light through the SPR effect to enhance the photocatalytic activities initiated by UV-light, and thus realize more effectively utilization of the whole solar spectrum for energy conversion. PMID:27215703

  16. Surface Plasmon Enhanced Photocatalysis of Au/Pt-decorated TiO2 Nanopillar Arrays.

    PubMed

    Shuang, Shuang; Lv, Ruitao; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    The low quantum yields and lack of visible light utilization hinder the practical application of TiO2 in high-performance photocatalysis. Herein, we present a design of TiO2 nanopillar arrays (NPAs) decorated with both Au and Pt nanoparticles (NPs) directly synthesized through successive ion layer adsorption and reaction (SILAR) at room temperature. Au/Pt NPs with sizes of ~4 nm are well-dispersed on the TiO2 NPAs as evidenced by electron microscopic analyses. The present design of Au/Pt co-decoration on the TiO2 NPAs shows much higher visible and ultraviolet (UV) light absorption response, which leads to remarkably enhanced photocatalytic activities on both the dye degradation and photoelectrochemical (PEC) performance. Its photocatalytic reaction efficiency is 21 and 13 times higher than that of pure TiO2 sample under UV-vis and visible light, respectively. This great enhancement can be attributed to the synergy of electron-sink function of Pt and surface plasmon resonance (SPR) of Au NPs, which significantly improves charge separation of photoexcited TiO2. Our studies demonstrate that through rational design of composite nanostructures one can harvest visible light through the SPR effect to enhance the photocatalytic activities initiated by UV-light, and thus realize more effectively utilization of the whole solar spectrum for energy conversion. PMID:27215703

  17. Hierarchical nanostructures of Au@ZnO: antibacterial and antibiofilm agent.

    PubMed

    Gholap, Haribhau; Warule, Sambhaji; Sangshetti, Jaiprakash; Kulkarni, Gauri; Banpurkar, Arun; Satpute, Surekha; Patil, Rajendra

    2016-07-01

    The perpetual use of antibiotics against pathogens inadvertently altered their genes that have translated into an unprecedented resistance in microorganisms in the twenty-first century. Many researchers have formulated bactericidal and bacteriostatic inorganic nanoparticle-based antiseptics that may be linked to broad-spectrum activity and far lower propensity to induce microbial resistance than organic-based antibiotics. Based on this line, herein, we present observations on microbial abatement using gold-based zinc oxide nanostructures (Au@ZnO) which are synthesized using hydrothermal route. Inhibition of microbial growth and biofilm using Au@ZnO is a unique feature of our study. Furthermore, this study evinces antimicrobial and antibiofilm mechanisms of photo-eradiated Au@ZnO by disruption of cellular functions and biofilms via reactive oxygen species (ROS)-dependent generation of superoxide anion radical. The present study is significant as it introduces novel functionalities to Au@ZnO in the biomedical field which can be extended to other species of microbial pathogens. PMID:26952109

  18. Surface Plasmon Enhanced Photocatalysis of Au/Pt-decorated TiO2 Nanopillar Arrays

    NASA Astrophysics Data System (ADS)

    Shuang, Shuang; Lv, Ruitao; Xie, Zheng; Zhang, Zhengjun

    2016-05-01

    The low quantum yields and lack of visible light utilization hinder the practical application of TiO2 in high-performance photocatalysis. Herein, we present a design of TiO2 nanopillar arrays (NPAs) decorated with both Au and Pt nanoparticles (NPs) directly synthesized through successive ion layer adsorption and reaction (SILAR) at room temperature. Au/Pt NPs with sizes of ~4 nm are well-dispersed on the TiO2 NPAs as evidenced by electron microscopic analyses. The present design of Au/Pt co-decoration on the TiO2 NPAs shows much higher visible and ultraviolet (UV) light absorption response, which leads to remarkably enhanced photocatalytic activities on both the dye degradation and photoelectrochemical (PEC) performance. Its photocatalytic reaction efficiency is 21 and 13 times higher than that of pure TiO2 sample under UV-vis and visible light, respectively. This great enhancement can be attributed to the synergy of electron-sink function of Pt and surface plasmon resonance (SPR) of Au NPs, which significantly improves charge separation of photoexcited TiO2. Our studies demonstrate that through rational design of composite nanostructures one can harvest visible light through the SPR effect to enhance the photocatalytic activities initiated by UV-light, and thus realize more effectively utilization of the whole solar spectrum for energy conversion.

  19. Large coincidence lattice on Au/Fe3O4 incommensurate structure for spintronic applications

    NASA Astrophysics Data System (ADS)

    Muñoz-Noval, Alvaro; Rubio-Zuazo, Juan; Salas-Colera, Eduardo; Serrano, Aida; Rubio-Marcos, Fernando; Castro, Germán R.

    2015-11-01

    The design of metallic hybrid systems for spintronics has been widely studied during the past decade, motivated by the promising technological applications of these materials. Nevertheless, the importance of preserving the native structure and properties of the interfaces is often ignored. Here, we present the fabrication of nanocrystalline Au (0 0 1) onto a single oriented Fe3O4 (0 0 1) thin film as a promising hybrid system to develop spintronic devices by growing Au over the Fe3O4 by using a simple one-pot Pulsed Laser Deposition (PLD) approach. The structural coupling between Au nanocrystals and Fe3O4 layer results in the development of an incommensurate structure based on a coincidence lattice of order 35, which preserves the intrinsic properties of the Au nanocrystals, the Fe3O4 matrix and the interface between them. The general strategy described in the present work preserves the structure and main intrinsic properties of the constituting materials, being a fundamental issue for the future development of spintronic devices.

  20. Centrality Dependence of Charged-Hadron Transverse-Momentum Spectra in d+Au Collisions at (sNN)=200 GeV

    NASA Astrophysics Data System (ADS)

    Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; Becker, B.; Betts, R. R.; Bickley, A. A.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; García, E.; Gburek, T.; George, N.; Gulbrandsen, K.; Gushue, S.; Halliwell, C.; Hamblen, J.; Harrington, A. S.; Henderson, C.; Hofman, D. J.; Hollis, R. S.; Hołyński, R.; Holzman, B.; Iordanova, A.; Johnson, E.; Kane, J. L.; Khan, N.; Kulinich, P.; Kuo, C. M.; Lee, J. W.; Lin, W. T.; Manly, S.; Mignerey, A. C.; Noell, A.; Nouicer, R.; Olszewski, A.; Pak, R.; Park, I. C.; Pernegger, H.; Reed, C.; Remsberg, L. P.; Roland, C.; Roland, G.; Sagerer, J.; Sarin, P.; Sawicki, P.; Sedykh, I.; Skulski, W.; Smith, C. E.; Steinberg, P.; Stephans, G. S.; Sukhanov, A.; Teng, R.; Tonjes, M. B.; Trzupek, A.; Vale, C.; van Nieuwenhuizen, G. J.; Verdier, R.; Veres, G. I.; Wadsworth, B.; Wolfs, F. L.; Wosiek, B.; Woźniak, K.; Wuosmaa, A. H.; Wysłouch, B.; Zhang, J.

    2003-08-01

    We have measured transverse momentum distributions of charged hadrons produced in d+Au collisions at (sNN)=200 GeV. The spectra were obtained for transverse momenta 0.25presented in comparison to p+p¯ collisions at the same collision energy. With increasing centrality, the yield at high transverse momenta increases more rapidly than the overall particle density, leading to a strong modification of the spectral shape. This change in spectral shape is qualitatively different from observations in Au+Au collisions at the same energy. The results provide important information for discriminating between different models for the suppression of high-pT hadrons observed in Au+Au collisions.

  1. Centrality dependence of charged-hadron transverse-momentum spectra in d+Au collisions at sqrt[s(NN)]=200 GeV.

    PubMed

    Back, B B; Baker, M D; Ballintijn, M; Barton, D S; Becker, B; Betts, R R; Bickley, A A; Bindel, R; Budzanowski, A; Busza, W; Carroll, A; Decowski, M P; García, E; Gburek, T; George, N; Gulbrandsen, K; Gushue, S; Halliwell, C; Hamblen, J; Harrington, A S; Henderson, C; Hofman, D J; Hollis, R S; Hołyński, R; Holzman, B; Iordanova, A; Johnson, E; Kane, J L; Khan, N; Kulinich, P; Kuo, C M; Lee, J W; Lin, W T; Manly, S; Mignerey, A C; Noell, A; Nouicer, R; Olszewski, A; Pak, R; Park, I C; Pernegger, H; Reed, C; Remsberg, L P; Roland, C; Roland, G; Sagerer, J; Sarin, P; Sawicki, P; Sedykh, I; Skulski, W; Smith, C E; Steinberg, P; Stephans, G S F; Sukhanov, A; Teng, R; Tonjes, M B; Trzupek, A; Vale, C; van Nieuwenhuizen, G J; Verdier, R; Veres, G I; Wadsworth, B; Wolfs, F L H; Wosiek, B; Woźniak, K; Wuosmaa, A H; Wysłouch, B; Zhang, J

    2003-08-15

    We have measured transverse momentum distributions of charged hadrons produced in d+Au collisions at sqrt[s(NN)]=200 GeV. The spectra were obtained for transverse momenta 0.25presented in comparison to p+pmacr; collisions at the same collision energy. With increasing centrality, the yield at high transverse momenta increases more rapidly than the overall particle density, leading to a strong modification of the spectral shape. This change in spectral shape is qualitatively different from observations in Au+Au collisions at the same energy. The results provide important information for discriminating between different models for the suppression of high-p(T) hadrons observed in Au+Au collisions. PMID:12935007

  2. An Exploration of Catalytic Chemistry on Au/Ni(111)

    SciTech Connect

    Sylvia T. Ceyer

    2011-12-09

    This project explored the catalytic oxidation chemistry that can be effected on a Au/Ni(111) surface alloy. A Au/Ni(111) surface alloy is a Ni(111) surface on which less than 60% of the Ni atoms are replaced at random positions by Au atoms. The alloy is produced by vapor deposition of a small amount of Au onto Ni single crystals. The Au atoms do not result in an epitaxial Au overlayer or in the condensation of the Au into droplets. Instead, Au atoms displace and then replace Ni atoms on a Ni(111) surface, even though Au is immiscible in bulk Ni. The two dimensional structure of the clean Ni surface is preserved. This alloy is found to stabilize an adsorbed peroxo-like O2 species that is shown to be the critical reactant in the low temperature catalytic oxidation of CO and that is suspected to be the critical reactant in other oxidation reactions. This investigation revealed a new, practically important catalyst for CO oxidation that has since been patented.

  3. Heatless synthesis of well dispersible Au nanoparticles using pectin biopolymer.

    PubMed

    Ahmed, Hanan B; Zahran, M K; Emam, Hossam E

    2016-10-01

    Due to its potency to utilize in enormous applications, preparation of nanogold is of interest. Moreover, getting of highly dispersed nanogold with small size is extremely needful in specific fields. Herein, Au nanocolloid was prepared using alkali catalyzed pectin biopolymer. Pectin was concurrently used as reductant for Au ions and stabilizer for the produced Au nanoparticles (AuNPs). Reducing sugars were evaluated in the colloidal solution reflecting the role alkali in catalytic degradation of pectin to produce much powerful reducing moieties. The obtained Au nanocolloid was monitored via changing in color, UV-visible spectral and transmission electron microscopy. Using of NaOH as strong alkali achieving rapid rate of degradation reaction, resulted in 0.45g/L reducing sugars from 0.2g/L pectin which produced AuNPs with mean size of 6.5nm. In case of Na2CO3 which attained slow degradation rate led to, slightly low reducing sugar content (0.41g/L), fabricated comparatively size of AuNPs (7.5nm). In both cases, well distributed AuNPs was obtained with suitable stabilization up to 5 months and Na2CO3 exhibited higher stability. The current successful method used to produce small sized AuNPs with high dispersion is an innovative, one-step, easily, costless, energy saving and eco-friendly method. PMID:27212212

  4. Local anodic oxidation patterning of Au deposited Si surfaces.

    PubMed

    Vijaykumar, T; Kulkarni, G U

    2009-09-01

    Nanopatterning of Si(100) surfaces deposited with Au films from physical and chemical methods, has been carried out using a AFM set up mounted with a conducting tip. At a tip bias of -12 V, the LAO patterns drawn on various Au/SiOx surfaces have been compared with those on bare Si. The height of the oxide patterns is several times higher in the case of Au covered Si surfaces compared to patterns on bare Si surface. The enhancement in LAO is related to the catalytic activity of Au nanoparticulates at SiOx interface. PMID:19928226

  5. Prolonged reorganization of thiol-capped Au nanoparticles layered structures

    NASA Astrophysics Data System (ADS)

    Kundu, Sarathi; Das, Kaushik; Konovalov, Oleg

    2013-09-01

    Prolonged reorganization behaviour of mono-, di-, tri- and multi-layer films of Au nanoparticles prepared by Langmuir-Blodgett method on hydrophobic Si(001) substrates have been studied by using X-ray scattering techniques. Out-of-plane study shows that although at the initial stage the reorganization occurs through the compaction of the films keeping the layered structure unchanged but finally all layered structures modify to monolayer structure. Due to this reorganization the Au density increases within the nanometer thick films. In-plane study shows that inside the reorganized films Au nanoparticles are distributed randomly and the particle size modifies as the metallic core of Au nanoparticles coalesces.

  6. Layer growth in Au-Pb/In solder joints

    SciTech Connect

    Yost, F.G.; Ganyard, F.P.; Karnowsky, M.M.

    1986-01-01

    The solid state reaction between a Pb-In solder alloy and thin film Au has been investigated at ten aging temperatures ranging from 70 to 170/sup 0/C. Also, bulk Au-solder samples were aged at 150/sup 0/C for metallographic analysis. No significant difference was found between the aging behavior of thin and bulk Au specimens. A thin single phase layer of Au/sub 9/In/sub 4/ was found adjacent to Au while a thick two-phase layer of AuIn/sub 2/ and Pb was found between Au/sub 9/In/sub 4/ and solder. The Pb phase was shown to have considerable mobility and able to ripen at room temperature. Peculiar planar interface instabilities and voids in the Au-Au/sub 9/In/sub 4/ interface were found. The total layer thickness was found to vary linearly with aging time, indicating an interface-controlled reaction. An activation energy of 14,000 calories per mole was found by regression analysis of the kinetic data.

  7. Density functional study of the cysteine adsorption on Au nanoclusters

    NASA Astrophysics Data System (ADS)

    Pérez, L. A.; López-Lozano, X.; Garzón, I. L.

    2009-04-01

    The adsorption of the cysteine amino acid (H-SCβH2-CαH-NH2-COOH) on the Au55 cluster is investigated through density functional theory calculations. Two isomers, with icosahedral (Ih) and chiral (C1) geometries, of the Au55 cluster are used to calculate the adsorption energy of the cysteine on different facets of these isomers. Results, only involving the S(thiolate)-Au bonding show that the higher adsorption energies are obtained when the sulfur atom is bonded to an asymmetrical bridge site at the facet containing Au atoms with the lowest coordination of the C1 cluster isomer.

  8. Electron paramagnetic resonance in positively charged Au25 molecular nanoclusters.

    PubMed

    Akbari-Sharbaf, Arash; Hesari, Mahdi; Workentin, Mark S; Fanchini, Giovanni

    2013-01-14

    In this study, we investigated the unpaired electrons and singly occupied molecular orbitals (SOMO) of positively charged Au(25) molecular clusters using solid-state electron paramagnetic resonance (EPR). The EPR powder spectra of the positively charged (Au(25) (+)) and neutral (Au(25) (0)) species of Au(25) are discussed and compared. Our study demonstrates that Au(25) (+) is paramagnetic with a SOMO that is mostly localized about the central gold atom in the core of the molecule and possesses a strong p-type atomic character. The unpaired electron spin is demonstrated to strongly interact with the nuclear spins from other (197)Au nuclei in the core of Au(25) (+) molecules and the hyperfine tensor describing such interaction was extracted from the comparison of the EPR spectra with quantum mechanical simulations assuming an anisotropic structure of the core. Our simulations suggest that the core of Au(25) (+) molecular clusters is more distorted than in the corresponding neutral counterpart. They also confirm previous hypotheses suggesting that the icosahedral core of Au(25) (+) experiences contraction with decreasing temperature. PMID:23320681

  9. Atomistic simulations of Au-silica nanocomposite film growth

    SciTech Connect

    Khan, Saif A.; Heinig, K.-H.; Avasthi, D. K.

    2011-05-01

    The growth of Au-silica nanocomposite film is simulated in the framework of kinetic three dimensional lattice Monte Carlo simulations considering the basic phenomena in the deposition process. In case of co-sputter deposition, the growth kinetics of nanoparticles has been studied taking into consideration the effect of the energetic sputtered species reaching the surface of the film during deposition. Formation of Au nanorod like structures are predicted under certain growth conditions particularly when surface diffusion assisted phase separation plays the dominant role and bulk kinetics is frozen. The observed dependence of the Au nanoparticle size on Au/silica ratio is in agreement with the experimental results.

  10. Enhanced photoluminescence in Au-embedded ITO nanowires.

    PubMed

    Kim, Hyunsu; Park, Sunghoon; Jin, Changhyun; Lee, Chongmu

    2011-12-01

    Gold (Au)-embedded indium tin oxide (ITO) nanowires were synthesized by thermal evaporation of a mixture of In(2)O(3,) SnO(2) and graphite powders on Si (100) substrates coated with Au thin films followed by annealing. At the initial stages of annealing, Au formed a continuous linear core located along the long axis of each ITO nanowire. The morphology of the Au core changed from a continuous line to a discrete line, and then to a droplet-like chain, finally evolving into a peapod in which crystalline Au nanoparticles were encapsulated in crystalline ITO with increasing annealing temperature. The ITO nanowires with the Au core showed an emission band at ~380 nm in the ultraviolet region. The ultraviolet emission intensity increased rapidly with increasing annealing temperature. The intensity of emission from the Au-peapod ITO nanowires (annealed at 750 °C) was approximately 20 times higher than that of the emission from the Au-core/ITO-shell ITO nanowires with a continuous linear shaped-Au core (annealed at 550 °C). This ultraintense ultraviolet emission might have originated mainly from the enhanced crystalline quality of the annealed ITO nanowires. PMID:22087582

  11. Component conversion from pure Au nanorods to multiblock Ag-Au-Ag nanorods assisted by Pt nanoframe templates.

    PubMed

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Kim, Seong Kyu; Park, Sungho

    2016-07-14

    We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications. PMID:27315144

  12. Diffusion of the Linear CH3S-Au-SCH3 Complex on Au(111) from First Principles

    SciTech Connect

    Jiang, Deen; Dai, Sheng

    2009-01-01

    Recent experimental and computational advances have clearly established the importance of the linear alkylthiolate-Au-alkylthiolate (RS-Au-SR) complex at the interface between the thiolate groups and the gold surface. By using density functional theory-based first principles method, here we show that the elementary diffusion step of this linear complex on Au(111) has a barrier of only {approx}0.5 eV in the case of methylthiolate, indicating great mobility of the linear complex on Au(111). The role of this low barrier in the formation of a self-assembled monolayer of thiolate groups in the form of RS-Au-SR on Au(111) is discussed.

  13. Observation of D0 Meson Nuclear Modifications in Au +Au Collisions at √sNN =200 GeV

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Contin, G.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Olvitt, D. L.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, J. L.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2014-10-01

    We report the first measurement of charmed-hadron (D0) production via the hadronic decay channel (D0→K-+π+) in Au +Au collisions at √sNN =200 GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, Nbin, from p +p to central Au +Au collisions. The D0 meson yields in central Au +Au collisions are strongly suppressed compared to those in p+p scaled by Nbin, for transverse momenta pT>3 GeV /c, demonstrating significant energy loss of charm quarks in the hot and dense medium. An enhancement at intermediate pT is also observed. Model calculations including strong charm-medium interactions and coalescence hadronization describe our measurements.

  14. Heterostructured Au/Pd-M (M = Au, Pd, Pt) nanoparticles with compartmentalized composition, morphology, and electrocatalytic activity.

    PubMed

    Lutz, Patrick S; Bae, In-Tae; Maye, Mathew M

    2015-10-14

    The synthesis, processing, and galvanic exchange of three heterostructured nanoparticle systems is described. The surface accessibility and redox potential of a Au/Pd-Ag dumbbell nanoparticle, where a Au/Pd core/shell region, and a silver region make up the domains, was used to prepare the new nanostructures with controlled composition, morphology, and microstructure. Results indicate that the silver domain was particularly susceptible to galvanic displacement, and was exchanged to Au/Pd-M (M = Au, Pd, Pt). Interestingly, the dumbbell morphology remained after exchange, and the silver region was transformed to hollow, parachute, or concentric domains respectively. The morphology and microstructure change was visualized via TEM and HRTEM, and the composition changes were probed via STEM-EDS imaging and XPS. The electrocatalytic activity of the Au/Pd-M towards methanol oxidation was studied, with results indicating that the Au/Pd-Pt nanoparticles had high activity attributed to the porous nature of the platinum domains. PMID:26351824

  15. Colorimetric aptasensing of ochratoxin A using Au@Fe3O4 nanoparticles as signal indicator and magnetic separator.

    PubMed

    Wang, Chengquan; Qian, Jing; Wang, Kun; Yang, Xingwang; Liu, Qian; Hao, Nan; Wang, Chengke; Dong, Xiaoya; Huang, Xingyi

    2016-03-15

    Gold nanoparticles (Au NPs) doped Fe3O4 (Au@Fe3O4) NPs have been synthesized by a facile one-step solvothermal method. The peroxidase-like activity of Au@Fe3O4 NPs was effectively enhanced due to the synergistic effect between the Fe3O4 NPs and Au NPs. On this basis, an efficient colorimetric aptasensor has been developed using the intrinsic dual functionality of the Au@Fe3O4 NPs as signal indicator and magnetic separator. Initially, the amino-modified aptamer specific for a typical mycotoxin, ochratoxin A (OTA), was surface confined on the amino-terminated glass beads surafce using glutaraldehyde as a linker. Subsequently, the amino-modified capture DNA (cDNA) was labeled with the amino-functionalized Au@Fe3O4 NPs and the aptasensor was thus fabricated through the hybridization reaction between cDNA and the aptamers. While upon OTA addition, aptamers preferred to form the OTA-aptamer complex and the Au@Fe3O4 NPs linked on the cDNA were released into the bulk solution. Through a simple magnetic separation, the collected Au@Fe3O4 NPs can produce a blue colored solution in the presence of 3,3',5,5'-tetramethylbenzidine and H2O2. When the reaction was terminated by addition of H(+) ions, the blue product could be changed into a yellow one with higher absorption intensity. This colorimetric aptasensor can detect as low as 30 pgmL(-1) OTA with high specificity. To the best of our knowledge, the present colorimetric aptasensor is the first attempt to use the peroxidase-like activity of nanomaterial for OTA detection, which may provide an acttractive path toward routine quality control of food safety. PMID:26583358

  16. Polymorphism in magic-sized Au144(SR)60 clusters

    NASA Astrophysics Data System (ADS)

    Jensen, Kirsten M. Ø.; Juhas, Pavol; Tofanelli, Marcus A.; Heinecke, Christine L.; Vaughan, Gavin; Ackerson, Christopher J.; Billinge, Simon J. L.

    2016-06-01

    Ultra-small, magic-sized metal nanoclusters represent an important new class of materials with properties between molecules and particles. However, their small size challenges the conventional methods for structure characterization. Here we present the structure of ultra-stable Au144(SR)60 magic-sized nanoclusters obtained from atomic pair distribution function analysis of X-ray powder diffraction data. The study reveals structural polymorphism in these archetypal nanoclusters. In addition to confirming the theoretically predicted icosahedral-cored cluster, we also find samples with a truncated decahedral core structure, with some samples exhibiting a coexistence of both cluster structures. Although the clusters are monodisperse in size, structural diversity is apparent. The discovery of polymorphism may open up a new dimension in nanoscale engineering.

  17. Polymorphism in magic-sized Au144(SR)60 clusters

    PubMed Central

    Jensen, Kirsten M.Ø.; Juhas, Pavol; Tofanelli, Marcus A.; Heinecke, Christine L.; Vaughan, Gavin; Ackerson, Christopher J.; Billinge, Simon J. L.

    2016-01-01

    Ultra-small, magic-sized metal nanoclusters represent an important new class of materials with properties between molecules and particles. However, their small size challenges the conventional methods for structure characterization. Here we present the structure of ultra-stable Au144(SR)60 magic-sized nanoclusters obtained from atomic pair distribution function analysis of X-ray powder diffraction data. The study reveals structural polymorphism in these archetypal nanoclusters. In addition to confirming the theoretically predicted icosahedral-cored cluster, we also find samples with a truncated decahedral core structure, with some samples exhibiting a coexistence of both cluster structures. Although the clusters are monodisperse in size, structural diversity is apparent. The discovery of polymorphism may open up a new dimension in nanoscale engineering. PMID:27297400

  18. Polymorphism in magic-sized Au144(SR)60 clusters.

    PubMed

    Jensen, Kirsten M Ø; Juhas, Pavol; Tofanelli, Marcus A; Heinecke, Christine L; Vaughan, Gavin; Ackerson, Christopher J; Billinge, Simon J L

    2016-01-01

    Ultra-small, magic-sized metal nanoclusters represent an important new class of materials with properties between molecules and particles. However, their small size challenges the conventional methods for structure characterization. Here we present the structure of ultra-stable Au144(SR)60 magic-sized nanoclusters obtained from atomic pair distribution function analysis of X-ray powder diffraction data. The study reveals structural polymorphism in these archetypal nanoclusters. In addition to confirming the theoretically predicted icosahedral-cored cluster, we also find samples with a truncated decahedral core structure, with some samples exhibiting a coexistence of both cluster structures. Although the clusters are monodisperse in size, structural diversity is apparent. The discovery of polymorphism may open up a new dimension in nanoscale engineering. PMID:27297400

  19. Coverage Dependent Assembly of Anthraquinone on Au(111)

    NASA Astrophysics Data System (ADS)

    Conrad, Brad; Deloach, Andrew; Einstein, Theodore; Dougherty, Daniel

    A study of adsorbate-adsorbate and surface state mediated interactions of anthraquinone (AnQ) on Au(111) is presented. We utilize scanning tunneling microscopy (STM) to characterize the coverage dependence of AnQ structure formation. Ordered structures are observed up to a single monolayer (ML) and are found to be strongly dependent on molecular surface density. While the complete ML forms a well-ordered close-packed layer, for a narrow range of sub-ML coverages irregular close-packed islands are observed to coexist with a disordered pore network linking neighboring islands. This network displays a characteristic pore size and at lower coverages, the soliton walls of the herringbone reconstruction are shown to promote formation of distinct pore nanostructures. We will discuss these nanostructure formations in the context of surface mediated and more direct adsorbate interactions.

  20. Contact Hysteresis and Friction of Alkanethiol SAMs on Au

    SciTech Connect

    Houston, J.E.; Kiely, J.D.

    1998-10-14

    Nanoindentation has been combhed with nanometer-scale friction measurements to identi~ dissipative mechanisms responsible for friction in hexadecanethiol self-assembled monolayer on Au. We have demonstrated that friction is primarily due to viscoelastic relaxations within the films, which give rise to contact hysteresis when deformation rates are within the ranges of 5 and 200 k. We observe that this contact hysteresis increases with exposure to air such that the friction coefficient increases from 0.004 to 0.075 when films are exposed to air for 40 days. Both hysteresis and friction increase with probe speed, and we present a model of friction that characterizes this speed dependence and which also predicts a linear dependence of friction on normal force in thin organic films. Finally, we identify several short-term wear regimes and identify that wear changes dramatically when fdms age.

  1. Au@MnS@ZnS Core/Shell/Shell Nanoparticles for Magnetic Resonance Imaging and Enhanced Cancer Radiation Therapy.

    PubMed

    Li, Meifang; Zhao, Qi; Yi, Xuan; Zhong, Xiaoyan; Song, Guosheng; Chai, Zhifang; Liu, Zhuang; Yang, Kai

    2016-04-20

    Although conventional radiotherapy (RT) has been widely used in the clinic to treat cancer, it often has limited therapeutic outcomes and severe toxic effects. There is still a need to develop theranostic agents with both imaging and RT-enhancing functions to improve the accuracy and efficiency of RT. Herein we synthesize Au@MnS@ZnS core/shell/shell nanoparticles with polyethylene glycol (PEG) functionalization, yielding Au@MnS@ZnS-PEG nanoparticles with great stability in different physiological solutions and no significant cytotoxicity. It is found that Au@MnS@ZnS-PEG nanoparticles can enhance the cancer cell killing efficiency induced by RT, as evidenced by multiple in vitro assays. Owing to the existence of paramagnetic Mn(2+) in the nanoparticle shell, our Au@MnS@ZnS-PEG can be used as a contrast agent for T1-weighted magnetic resonance (MR) imaging, which reveals the efficient accumulation and retention of nanoparticles in the tumors of mice after intravenous injection. Importantly, by exposing tumor-bearing mice that were injected with Au@MnS@ZnS-PEG to X-ray irradiation, the tumor growth can be significantly inhibited. This result shows clearly improved therapeutic efficacy compared to RT alone. Furthermore, no obvious side effect of Au@MnS@ZnS-PEG is observed in the injected mice. Therefore, our work presents a new type of radiosensitizing agent, which is promising for the imaging-guided enhanced RT treatment of cancer. PMID:27039932

  2. Growth of a Au-Ni-Sn intermetallic compound on the solder-substrate interface after aging

    SciTech Connect

    Minor, Andrew M.; Morris, J.W., Jr.

    1999-12-16

    Au/Ni metallization has become increasingly common in microelectronic packaging when Cu pads are joined with Pb-Sn solder. The outermost Au layer serves to protect the pad from corrosion and oxidation and the Ni layer provides a diffusion barrier to inhibit detrimental growth of Cu-Sn intermetallics. As a result of reflowing eutectic Pb-Sn on top of Au/Ni metallization, the as-solidified joints have AuSn{sub 4} precipitates distributed throughout the bulk of the solder joint, and Ni{sub 3}Sn{sub 4} intermetallics at the interface. Recent work has shown that the Au-Sn redeposits onto the interface during aging, compromising the strength of the joint. The present work shows that the redeposited intermetallic layer is a ternary compound with stoichiometry Au{sub 0.5}Ni{sub 0.5}Sn{sub 4}. The growth of this intermetallic layer was investigated, and results show that the ternary compound is observed to grow after as little as 3 hours at 150 C and after 3 weeks at 150 C has grown to a thickness of 10 {micro}m. Additionally, methods for inhibiting the growth of the ternary layer were investigated and it was determined that multiple reflows, both with and without additional aging can substantially limit the thickness of the ternary layer.

  3. Non-centrosymmetric Au-SnO2 hybrid nanostructures with strong localization of plasmonic for enhanced photocatalysis application.

    PubMed

    Wu, Wei; Liao, Lei; Zhang, Shaofeng; Zhou, Juan; Xiao, Xiangheng; Ren, Feng; Sun, Lingling; Dai, Zhigao; Jiang, Changzhong

    2013-06-21

    We present an innovative approach to the production of sub-100 nm hollow Au-SnO2 hybrid nanospheres, employing a low-cost, surfactant-free and environmentally friendly solution-based route. The hollow hybrid nanostructures were synthesized using a seed-mediated hydrothermal method, which can be divided into two stages: (1) formation of multicore-shell Au@SnO2 nanoparticles (NPs) and (2) thermal diffusion and ripening to form hollow Au-SnO2 hybrid NPs. The morphology, optical properties and formation mechanism were determined by a collection of joint techniques. Photocatalytic degradation of Rhodamine B (RhB) in the liquid phase served as a probe reaction to evaluate the activity of the as-prepared hollow hybrid Au-SnO2 NPs under the irradiation of both visible light and ultraviolet light. Significantly, the as-obtained Au-SnO2 hybrid nanostructures exhibited enhanced visible light or UV photocatalytic abilities, remarkably superior to commercial pure SnO2 products and P25 TiO2, mainly owing to the effective electron hole separation at the SnO2-Au interfaces and strong localization of plasmonic near-fields effects. PMID:23685533

  4. Systematic Study on the Self-Assembled Hexagonal Au Voids, Nano-Clusters and Nanoparticles on GaN (0001).

    PubMed

    Pandey, Puran; Sui, Mao; Li, Ming-Yu; Zhang, Quanzhen; Kim, Eun-Soo; Lee, Jihoon

    2015-01-01

    Au nano-clusters and nanoparticles (NPs) have been widely utilized in various electronic, optoelectronic, and bio-medical applications due to their great potentials. The size, density and configuration of Au NPs play a vital role in the performance of these devices. In this paper, we present a systematic study on the self-assembled hexagonal Au voids, nano-clusters and NPs fabricated on GaN (0001) by the variation of annealing temperature and deposition amount. At relatively low annealing temperatures between 400 and 600°C, the fabrication of hexagonal shaped Au voids and Au nano-clusters are observed and discussed based on the diffusion limited aggregation model. The size and density of voids and nano-clusters can systematically be controlled. The self-assembled Au NPs are fabricated at comparatively high temperatures from 650 to 800°C based on the Volmer-Weber growth model and also the size and density can be tuned accordingly. The results are symmetrically analyzed and discussed in conjunction with the diffusion theory and thermodynamics by utilizing AFM and SEM images, EDS maps and spectra, FFT power spectra, cross-sectional line-profiles and size and density plots. PMID:26285135

  5. Systematic Study on the Self-Assembled Hexagonal Au Voids, Nano-Clusters and Nanoparticles on GaN (0001)

    PubMed Central

    Pandey, Puran; Sui, Mao; Li, Ming-Yu; Zhang, Quanzhen; Kim, Eun-Soo; Lee, Jihoon

    2015-01-01

    Au nano-clusters and nanoparticles (NPs) have been widely utilized in various electronic, optoelectronic, and bio-medical applications due to their great potentials. The size, density and configuration of Au NPs play a vital role in the performance of these devices. In this paper, we present a systematic study on the self-assembled hexagonal Au voids, nano-clusters and NPs fabricated on GaN (0001) by the variation of annealing temperature and deposition amount. At relatively low annealing temperatures between 400 and 600°C, the fabrication of hexagonal shaped Au voids and Au nano-clusters are observed and discussed based on the diffusion limited aggregation model. The size and density of voids and nano-clusters can systematically be controlled. The self-assembled Au NPs are fabricated at comparatively high temperatures from 650 to 800°C based on the Volmer-Weber growth model and also the size and density can be tuned accordingly. The results are symmetrically analyzed and discussed in conjunction with the diffusion theory and thermodynamics by utilizing AFM and SEM images, EDS maps and spectra, FFT power spectra, cross-sectional line-profiles and size and density plots. PMID:26285135

  6. Near-side azimuthal and pseudorapidity correlations using neutral strange baryons and mesons in d +Au , Cu + Cu, and Au + Au collisions at √{sN N}=200 GeV

    NASA Astrophysics Data System (ADS)

    Abelev, B.; Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Barnby, L. S.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bombara, M.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Gaillard, L.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, B.; Huang, X.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Jones, P. G.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov,