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Sample records for 1s xps spectra

  1. Simulation of XPS C1s spectra of organic monolayers by quantum chemical methods.

    PubMed

    Giesbers, Marcel; Marcelis, Antonius T M; Zuilhof, Han

    2013-04-16

    Several simple methods are presented and evaluated to simulate the X-ray photoelectron spectra (XPS) of organic monolayers and polymeric layers by density functional theory (DFT) and second-order Møller-Plesset theory (MP2) in combination with a series of basis sets. The simulated carbon (C1s) XPS spectra as obtained via B3LYP/6-311G(d,p) or M11/6-311G(d,p) calculations are in good agreement (average mean error <0.3 eV) with the experimental spectra, and good estimates of C1s spectra can be obtained via E(C1s)(exp) = 0.9698EC1s(theory) + 20.34 (in eV) (B3LYP/6-311G(d,p)). As a result, the simulated C1s XPS spectra can elucidate the binding energies of the different carbon species within an organic layer and, in this way, greatly aid the assignment of complicated C1s XPS spectra. The paper gives a wide range of examples, including haloalkanes, esters, (thio-)ethers, leaving groups, clickable functionalities, and bioactive moieties.

  2. A poly-epoxy surface explored by Hartree-Fock ΔSCF simulations of C1s XPS spectra

    NASA Astrophysics Data System (ADS)

    Gavrielides, A.; Duguet, T.; Esvan, J.; Lacaze-Dufaure, C.; Bagus, P. S.

    2016-08-01

    Whereas poly-epoxy polymers represent a class of materials with a wide range of applications, the structural disorder makes them difficult to model. In the present work, we use good experimental model samples in the sense that they are pure, fully polymerized, flat and smooth, defect-free, and suitable for ultrahigh vacuum x-ray photoelectron spectroscopy, XPS, experiments. In parallel, we perform Hartree-Fock, HF, calculations of the binding energies, BEs, of the C1s electrons in a model molecule composed of the two constituents of the poly-epoxy sample. These C1s BEs were determined using the HF ΔSCF method, which is known to yield accurate values, especially for the shifts of the BEs, ΔBEs. We demonstrate the benefits of combining rigorous theory with careful XPS measurements in order to obtain correct assignments of the C1s XPS spectra of the polymer sample. Both the relative binding energies—by the ΔSCF method—and relative intensities—in the sudden approximation, SA, are calculated. It results in an excellent match with the experimental spectra. We are able to identify 9 different chemical environments under the C1s peak, where an exclusively experimental work would have found only 3 contributions. In addition, we observe that some contributions are localized at discrete binding energies, whereas others allow a much wider range because of the variation of their second neighbor bound polarization. Therefore, HF-ΔSCF simulations significantly increase the spectral resolution of XPS and thus offer a new avenue for the exploration of the surface of polymers.

  3. XPS spectra of uranyl minerals and synthetic uranyl compounds. II: The O 1s spectrum

    NASA Astrophysics Data System (ADS)

    Schindler, M.; Hawthorne, F. C.; Freund, M. S.; Burns, P. C.

    2009-05-01

    The O 1s spectrum is examined for 19 uranyl minerals of different composition and structure. Spectra from single crystals were measured with a Kratos Axis Ultra X-ray Photoelectron Spectrometer with a magnetic-confinement charge-compensation system. Well-resolved spectra with distinct maxima, shoulders and inflections points, in combination with reported and measured binding energies for specific O 2- species and structural data of the uranyl minerals are used to resolve the fine structure of the O 1s envelope. The resolution of the O 1s spectra includes, for the first time, different O 2- bands, which are assigned to O atoms linking uranyl with uranyl polyhedra ( Usbnd Osbnd U) and O atoms of uranyl groups ( Odbnd Udbnd O). The resolved bands in the O 1s spectrum occur at distinct ranges in binding energy: bands for ( Usbnd Osbnd U) occur at 529.6-530.4 eV, bands for ( Odbnd Udbnd O) occur at 530.6-531.4 eV, bands for O 2- in the equatorial plane of the uranyl polyhedra linking uranyl polyhedra with ( TO n) groups ( T = Si, S, C, P, Se) ( Tsbnd O) occur at 530.9-532.2 eV; bands for (OH) groups in the equatorial plane of the uranyl polyhedra ( OH) occur at 532.0-532.5 eV, bands of (H 2O) groups in the interstitial complex of the uranyl minerals ( H2O interst) occur at 533.0-533.8 eV and bands of physisorbed (H 2O) groups on the surface of uranyl minerals ( H2O adsorb) occur at 534.8-535.2 eV. Treatment of uranyl minerals with acidic solutions results in a decrease in Usbnd Osbnd U and an increase in OH. Differences in the ratio of OH : Odbnd Udbnd O between the surface and bulk structure is larger for uranyl minerals with a high number of Usbnd Osbnd U and Tsbnd O species in the bulk structure which is explained by protonation of underbonded Usbnd O, Usbnd Osbnd U and Tsbnd O terminations on the surface. The difference in the ratio of H2O interst : Odbnd Udbnd O between the bulk and surface structures is larger for uranyl minerals with higher percentages of H2O

  4. Handbook of Monochromatic XPS Spectra, Semiconductors

    NASA Astrophysics Data System (ADS)

    Crist, B. Vincent

    2000-10-01

    This handbook is one of three containing an invaluable collection of research grade XPS Spectra. Each handbook concentrates on a specific family of materials (the elements and their native oxides, semiconductors and polymers) and is entirely self-contained. The introductory section to each handbook includes comprehensive information about the XPS instrument used, the materials and the advanced methods used to collect the spectra. Energy resolution settings, instrument characteristics, energy referencing methods, traceability, energy scale calibration details and transmission function are all reported. Among the many valuable features included in each of these handbooks are: ? All spectra were measured by using AlK monochromatic X-rays ? All spectra were collected in a self-consistent manner to maximise data reliability and quality ? All peaks in the wide spectra are fully annotated and accompanied by detailed atom % tables that report BEs for each of the labelled peaks ? Each high-energy resolution spectrum is peak-fitted and accompanied by detailed tables containing binding energies, FWHMs and relative percentages. In this volume 'Semiconductors' are contained XPS Spectra from a wide range of semiconductive materials and related materials, a rare tool for scientists and analysts in this area. Exclusive features of this volume include: ? Binding energies are accurate to +/- 0.08eV ? Charge compensation was done with a flood-gun mesh-screen system ? Valence band spectra document the occupied density of states (DOS) and the fundamental electronic nature of the semi-conductive materials analysed ? Analyses were done: "as received", "freshly fractured in air", "ion etched" and "chemically treated" ? Alphabetically organised by chemical abbreviations for ease of locating each material This handbook is an invaluable reference for materials scientists and electrical engineers in industry, academia and government laboratories interested in the analysis of semiconductors

  5. The Interpretation of XPS Spectra: Insights Into Materials Properties

    SciTech Connect

    Bagus, Paul S.; Ilton, Eugene S.; Nelin, Constance J.

    2013-06-01

    We review basic and advanced concepts needed for the correct analysis of XPS features. We place these concepts on rigorous foundations and explore their physical and chemical meanings without stressing the derivation of the mathematical formulations, which can be found in the cited literature. The significance and value of combining theory and experiment is demonstrated by discussions of the physical and chemical origins of the main and satellite XPS features for a variety of molecular and condensed phase materials.

  6. Quantitative analysis of satellite structures in XPS spectra of gold and silver

    NASA Astrophysics Data System (ADS)

    Pauly, N.; Yubero, F.; Tougaard, S.

    2016-10-01

    Identification of specific chemical states and local electronic environments at surfaces by X-ray photoelectron spectroscopy (XPS) is often difficult because it is not straightforward to quantitatively interpret the shape and intensity of shake-up structures that originate from the photoexcitation process. Indeed the shape and intensity of measured XPS structures are strongly affected by both extrinsic excitations due to electron transport out of the surface and intrinsic excitations induced by the sudden creation of the static core hole. These processes must be taken into account to quantitatively extract, from experimental XPS, the primary excitation spectrum of the considered transition which includes all effects that are part of the initial photo-excitation process, i.e. lifetime broadening, spin-orbit coupling, and multiplet splitting. It was previously shown [N. Pauly, S. Tougaard, F. Yubero, Surf. Sci. 620 (2014) 17] that both extrinsic and intrinsic excitations could be included in an effective energy-differential inelastic electron scattering cross section for XPS which is then convoluted with the primary excitation spectrum to model the full XPS spectrum. This method can thus be applied to determine the primary excitation spectrum from any XPS spectrum. We use this approach in the present paper to determine the Au 4f and Ag 3d photoemission spectra from pure metals. We observe that characteristic energy loss features of the XPS spectra are not only due to photoelectron energy losses. We thus prove the existence of a double shake-up process characterized by a 4d → 5s/5p transition for Ag and a 5d → 6s/6p transition for Au. We finally accurately quantify the energy position and intensity of these shake-up peaks.

  7. Application of high-resolution photoelectron spectroscopy: Vibrational resolved C 1s and O 1s spectra of CO adsorbed on Ni(100)

    SciTech Connect

    Foehlisch, A.; Nilsson, A.; Martensson, N.

    1997-04-01

    There are various effects which determine the line shape of a core-level electron spectrum. These are due to the finite life-time of the core hole, inelastic scattering of the outgoing photoelectron, electronic shake-up and shake-off processes and vibrational excitations. For free atoms and molecules the different contributions to the observed line shapes can often be well separated. For solids, surfaces and adsorbates the line shapes are in general much broader and it has in the past been assumed that no separation of the various contributions can be made. In the present report the authors will show that this is indeed not the case. Surprisingly, the vibrational fine structure of CO adsorbed on Ni(100) can be resolved in the C 1s and O 1s electron spectra. This was achieved by the combination of highly monochromatized soft X-rays from B18.0 with a high resolution Scienta 200 mm photoelectron spectrometer. X-ray photoelectron spectroscopy (XPS) with tunable excitation energy yields as a core level spectroscopy atomic and site-specific information. The presented measurements allow for a determination of internuclear distances and potential energy curves in corehole ionized adsorbed molecules. The authors analysis of the c(2x2) phase CO/Ni(100) on {open_quotes}top{close_quotes} yielded a vibrational splitting of 217 +/- 2 meV for C 1s ionization. For O 1s ionization a splitting of 173 +/- 8 meV was found.

  8. Vibrationally resolved high-resolution NEXAFS and XPS spectra of phenanthrene and coronene

    SciTech Connect

    Fronzoni, Giovanna; Baseggio, Oscar; Stener, Mauro; Hua, Weijie; Tian, Guangjun; Luo, Yi; Apicella, Barbara; Alfé, Michela; Simone, Monica de; Kivimäki, Antti; Coreno, Marcello

    2014-07-28

    We performed a combined experimental and theoretical study of the C1s Near-Edge X-ray Absorption Fine-Structure (NEXAFS) spectroscopy and X-ray Photoelectron Spectroscopy in the gas phase of two polycyclic aromatic hydrocarbons (phenanthrene and coronene), typically formed in combustion reactions. In the NEXAFS of both molecules, a double-peak structure appears in the C1s → LUMO region, which differ by less than 1 eV in transition energies. The vibronic coupling is found to play an important role in such systems. It leads to weakening of the lower-energy peak and strengthening of the higher-energy one because the 0 − n (n > 0) vibrational progressions of the lower-energy peak appear in nearly the same region of the higher-energy peak. Vibrationally resolved theoretical spectra computed within the Frank-Condon (FC) approximation and linear coupling model agree well with the high-resolution experimental results. We find that FC-active normal modes all correspond to in-plane vibrations.

  9. Matrix effects in the C 1s photoabsorption spectra of condensed naphthalene

    NASA Astrophysics Data System (ADS)

    Schmidt, Norman; Wenzel, Jan; Dreuw, Andreas; Fink, Rainer H.; Hieringer, Wolfgang

    2016-12-01

    High-resolution C 1s near-edge x-ray absorption fine structure (NEXAFS) spectra of naphthalene are investigated. By comparing the spectral signatures of condensed naphthalene molecules with those of naphthalene in the gas phase, we are able to unambiguously identify spectral features which are affected by the intermolecular interactions in the condensed phase. With the help of calculations using time-dependent density-functional theory and the second-order algebraic-diagrammatic construction scheme for the polarization propagator, resonances in the relevant energy range can be assigned to valence and Rydberg-like excitations. Thus, we obtain a more detailed identification of NEXAFS resonances beyond the present literature.

  10. Method for estimating ionicities of oxides using O1s photoelectron spectra

    SciTech Connect

    Wu, L. Q.; Li, Z. Z.; Tang, G. D. Qi, W. H.; Xue, L. C.; Ge, X. S.; Ding, L. L.; Li, Y. C.; Li, S. Q.

    2015-09-15

    The average valence, V{sub alO}, of the oxygen anions in the perovskite oxide BaTiO{sub 3}, was found using O1s photoelectron spectra to be −1.55. This experimental result is close to the theoretical value for BaTiO{sub 3} (−1.63) calculated by Cohen [Nature 358, 136 (1992)] using density functional theory. Using the same approach, we obtained values of V{sub alO} for several monoxides, and investigated the dependence of V{sub alO} and the ionicity on the second ionization energy, V(M{sup 2+}), of the metal cation. We found that the dependence of the ionicity on V(M{sup 2+}) in this work is close to that reported by Phillips [Rev. Mod. Phys. 42, 317 (1970)]. We therefore suggest that O1s photoelectron spectrum measurements should be accepted as a general experimental method for estimating the ionicity and average valence of oxygen anions.

  11. Recent advances in the practical and accurate calculation of core and valence XPS spectra of polymers: From interpretation to simulation?

    NASA Astrophysics Data System (ADS)

    Bureau, Christophe; Chong, Delano P.; Endo, Kazunaka; Delhalle, Joseph; Lecayon, Gérard; Le Moël, Alain

    1997-08-01

    Core and valence X-ray Photoelectron Spectroscopies (XPS) are routinely used to obtain information on the chemical composition, bonding and homogeneity of polymer surfaces. In spite of their apparent conceptual simplicity, Core and Valence Electron Binding Energies (CEBEs and VEBEs) a few electron-volts (eV) or fractions of an eV apart are difficult to interpret. We present some results obtained with various recent theoretical approaches. An emphasis is made on a procedure based on the Density Functional Theory (DFT) that enables the calculation of CEBEs and VEBEs which are in remarkable agreement with experiment. The method has been tested on numerous small (3-6 atoms) to fairly large (15-25 atoms) molecules, and shows an average absolute deviation with experiment of only 0.20 eV for CEBEs and 0.30 eV for VEBEs, i.e. compatible with the resolution of the best XPS experiments carried out at the moment. Besides the quality of its predictions, the procedure takes advantage of the speed and CPU time scaling of DFT as a function of system size: it is computationally tractable, even for surprisingly large systems such as polymers, and may be an interesting accurate alternative to interpret and simulate XPS-probing on real systems. We illustrate the usefullness and pitfalls of this approach in fundamental as well as applied fields such as in the study of Polyacrylonitrile (PAN), Polytetrafluoroethylene (PTFE), Polyvinyldifluoride (PVdF) and γ-Aminopropyltriethoxysilane (γ-APS, an adhesion promoter).

  12. Intensity analysis of XPS spectra to determine oxide uniformity - Application to SiO2/Si interfaces

    NASA Technical Reports Server (NTRS)

    Vasquez, R. P.; Grunthaner, F. J.

    1980-01-01

    A simple method of determining oxide uniformity is derived which requires no knowlege of film thickness, escape depth, or film composition. The method involves only the measurement of oxide and substrate intensities and is illustrated by analysis of XPS spectral data for thin SiO2 films grown both thermally and by low-temperature chemical vapor deposition on monocrystalline Si. A region 20-30 A thick is found near the SiO2/Si interface on thermally oxidized samples which has an inelastic mean free path 35% less than that found in the bulk oxide. This is interpreted as being due to lattice mismatch resulting in a strained region which is structurally, but not stoichiometrically, distinct from the bulk oxide.

  13. The influence of oxygen adsorption on the NEXAFS and core-level XPS spectra of the C{sub 60} derivative PCBM

    SciTech Connect

    Brumboiu, Iulia Emilia Eriksson, Olle; Brena, Barbara; Ericsson, Leif; Hansson, Rickard; Moons, Ellen

    2015-02-07

    Fullerenes have been a main focus of scientific research since their discovery due to the interesting possible applications in various fields like organic photovoltaics (OPVs). In particular, the derivative [6,6]-phenyl-C{sub 60}-butyric acid methyl ester (PCBM) is currently one of the most popular choices due to its higher solubility in organic solvents compared to unsubstituted C{sub 60}. One of the central issues in the field of OPVs is device stability, since modules undergo deterioration (losses in efficiency, open circuit voltage, and short circuit current) during operation. In the case of fullerenes, several possibilities have been proposed, including dimerization, oxidation, and impurity related deterioration. We have studied by means of density functional theory the possibility of oxygen adsorption on the C{sub 60} molecular moiety of PCBM. The aim is to provide guidelines for near edge X-ray absorption fine structure (NEXAFS) and X-ray photoelectron spectroscopy (XPS) measurements which can probe the presence of atomic or molecular oxygen on the fullerene cage. By analysing several configurations of PCBM with one or more adsorbed oxygen atoms, we show that a joint core level XPS and O1s NEXAFS investigation could be effectively used not only to confirm oxygen adsorption but also to pinpoint the bonding configuration and the nature of the adsorbate.

  14. Double-slit experiment with a polyatomic molecule: vibrationally resolved C 1s photoelectron spectra of acetylene

    NASA Astrophysics Data System (ADS)

    Argenti, L.; Thomas, T. D.; Plésiat, E.; Liu, X.-J.; Miron, C.; Lischke, T.; Prümper, G.; Sakai, K.; Ouchi, T.; Püttner, R.; Sekushin, V.; Tanaka, T.; Hoshino, M.; Tanaka, H.; Decleva, P.; Ueda, K.; Martín, F.

    2012-03-01

    We report the first evidence for double-slit interferences in a polyatomic molecule, which we have observed in the experimental carbon 1s photoelectron spectra of acetylene (or ethyne). The spectra have been measured over the photon energy range of 310-930 eV and show prominent oscillations in the intensity ratios σg(υ)/σu(υ) for the vibrational quantum numbers υ = 0,1 and for the ratios σs(υ = 1)/σs(υ = 0) for the symmetry s = g,u. The experimental findings are in very good agreement with ab initio density functional theory (DFT) calculations and are compatible with the Cohen-Fano mechanism of coherent emission from two equivalent atomic centers. This interpretation is supported by the qualitative predictions of a simple model in which the effect of nuclear recoil is taken into account to the lowest order. Our results confirm the delocalized character of the core hole created in the primary photoionization event and demonstrate that intramolecular core-hole coherence can survive the decoherent influence associated with the asymmetric nuclear degrees of freedom which are characteristic of polyatomic molecules.

  15. Effects of CeO2 on the XPS valence band spectra of coal under the combustion initialization stage at 400°C

    NASA Astrophysics Data System (ADS)

    Qi, Cheng-lin; Zhang, Jian-liang; Ma, Chao; Feng, Gen-sheng; Song, Zhong-ping

    2013-04-01

    In order to get the catalytic mechanism of CeO2 on graphite and coal at 400°C, the morphologies of coal, graphite, and CeO2 before and after combustion were analyzed through X-ray photoelectron spectroscopy (XPS). It is found that the particle size of coal is mostly between 11.727 and 64.79 μm, while the particle size of CeO2 is between 1.937 and 11.79 μm. The agglomeration of coal and CeO2 can be seen by scanning electron microscopy (SEM) after reaction. XPS results show that with the addition of CeO2, the intensity of binding energy gets stronger, but there is no energy peak transition. Comparing the character of coal with and without the addition of CeO2, it can be seen that the C-C bond fractures first at 400°C, while the C-H energy-band takes electrons at the same time to be far away from the Fermi level, and the O 2s, O 2p, and C sp hybrid orbitals are all excited. Adding CeO2 can enhance the activity of the whole coal. In addition, through XPS analysis, combined with the oxygen transfer theory and the electron transfer theory, the catalytic mechanism of CeO2 for pulverized coal combustion could be obtained.

  16. Site-specific recoil-induced effects on inner-shell photoionization of linear triatomic molecules: N 1 s photoelectron spectra of N2 O

    NASA Astrophysics Data System (ADS)

    Krivosenko, Yu. S.; Pavlychev, A. A.

    2016-11-01

    We investigate hard X-ray ionization of linear triatomic molecules accenting recoil-induced effects on the dynamics of molecular frame. This dynamics is studied within the two-springs and harmonic approximations. The mode-channel relationship connecting the excitations of vibrational, rotational and translational degrees of freedom with the Σ → Σ and Σ → Π photoionization channels is applied to compute the N 1s-1 photoelectron spectra of molecular N2 O for various photon energies. The distinct ionized-site- and molecular-orientation-specific changes in the vibration structure of the 1 s photoelectron lines of terminal and central nitrogen atoms are revealed and discussed.

  17. Rotationally resolved S1<-- S0 electronic spectra of fluorene, carbazole, and dibenzofuran: evidence for Herzberg-Teller coupling with the S2 state.

    PubMed

    Yi, John T; Alvarez-Valtierra, Leonardo; Pratt, David W

    2006-06-28

    Rotationally resolved fluorescence excitation spectra of the S1 <-- S0 origin bands and higher vibronic bands of fluorene (FLU), carbazole (CAR), and dibenzofuran (DBF) have been observed and assigned. Analyses of these data show that replacement of the CH2 group in FLU with a NH group in CAR and an O atom in DBF produces only localized changes in structure, in the ground state. But the three molecules exhibit different changes in geometry when they are excited by light. The S1 states of the three molecules also are electronically very different. The S1 <-- S0 transition moments of CAR and DBF are parallel to the C2 symmetry axis whereas the corresponding transition moment in FLU is perpendicular to this axis. Herzberg-Teller coupling involving the S2 state also has been observed in the spectra of higher vibronic bands of CAR and DBF. Possible reasons for these behaviors are discussed.

  18. Revisiting Vibrational Circular Dichroism Spectra of (S)-(+)-Carvone and (1S,2R,5S)-(+)-Menthol Using SimIR/VCD Method.

    PubMed

    Shen, Jian; Li, Yi; Vaz, Roy; Izumi, Hiroshi

    2012-08-14

    The VCD spectra of (S)-(+)-carvone and (1S,2R,5S)-(+)-menthol are recalculated using the DFT method with extended conformation and configuration spaces. The calculated individual and averaged spectra are compared against observed ones using the previously reported similarity index, SV. It is found that the SV population forms approximately two normal distributions, depending on whether a spectrum matches the observed one or not. This statistical character can be used to estimate the error in absolute configuration (AC) assessments. To avoid erroneous AC assignments and incomplete conformation searching, it is advisible to employ a minimum |SV| of 0.2 and maximize it using conformation averaging. It is demonstrated that this approach is suitable and robust for flexible chiral molecules.

  19. XPS study of protein adsorption onto nanocrystalline aluminosilicate microparticles

    NASA Astrophysics Data System (ADS)

    Vanea, E.; Simon, V.

    2011-01-01

    X-ray photoelectron spectroscopy (XPS) was used to study the interaction of two different sized proteins, bovine serum albumin (BSA) and fibrinogen, with an aluminosilicate system containing yttrium and iron that is a potential biomaterial. Serum albumin and fibrinogen are two major plasma proteins and the most relevant proteins adsorbed on the surface of biomaterials in blood contact. The aluminosilicate samples were incubated for several exposure times, up to 24 h, in simulated body fluid enriched with BSA, and in buffered fibrinogen solution. Time dependence of proteins adsorption onto surface of the investigated samples is reflected by the evolution of the new N 1s photoelectron peak and by the modification of C 1s core-level spectra recorded from the samples immersed in protein solution.

  20. XPS Study of Plasma- and Argon Ion-Sputtered Polytetrafluoroethylene

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Kliss, Mark (Technical Monitor)

    1997-01-01

    The similarity of plasma-polymerized tetrafluoroethylene (PPTFE) and the fluoropolymer film deposited by rf (radio frequency) plasma sputtering (SPTFE) of polytetrafluoroethylene (PTFE), noted earlier in the literature, has been reconfirmed. FT-IR (Fourier Transform Infrared), XPS (X ray Photoelectron Spectroscopy) and UV (ultraviolet) spectroscopy has been employed in apparently the first study to involve preparation of PPTFE and SPTFE in the same reactor and under comparable low-power plasma conditions. Most of the work concerned the use of He or Ar as sputtering gas, but some runs were also carried out with the other rare gases Ne, Kr and Xe. The C1s XPS spectra of SPTFE films displayed a relatively higher content of CF2 groups, and yielded higher F/C (fluorine / carbon) ratios, than PPTFE films, while the SPTFE films were somewhat more transparent in the UV than PPTFE. The F/C ratios for SPTFE were essentially independent of the rare gas used for sputtering. Increasing rf power from 10 to 50 W for Xe plasma-sputtering of PTFE resulted in successively lower F/C ratios (1.55 to 1.21), accompanied by sputtering of the glass reactor occurring at 40 W and above. Some limited XPS, FT-IR and UV data are presented on Ar ion-sputtered PTFE.

  1. XPS Observations of Crystal Field Splitting in TiO2 Thin Films in Quantum Confinement Approach

    NASA Astrophysics Data System (ADS)

    Sushkova, Natalya

    2015-03-01

    Transition metal oxides attract increased interest due to amazing electrical and magnetic properties and their outstanding applications designated by relative d-band redistributions that are shifted in such a way that narrow bands arranged by localized electrons are situated in the vicinity of EF. Different kinds of lattice distortions caused by doping and/or quantum size confinement of TM oxides are assigned to remarkable phenomenon Mott metal-insulator transitions, when mutual metal-oxide orbital arrangement changes dramatically. There is a widespread consensus that strong electron correlations are responsible for that change and magnetic excitation is one of manifestations of these correlations. Here we are presenting XPS study of titanium dioxide nanocrystal formations on silicon substrate with native oxide. The dynamic changes in XPS spectra were used for analysis of TiO2 thin films with mass thicknesses up to 2 monolayers formed by redox reactions of sputtered Ti on Si(100) substrate with native oxide implemented in situ under UHV conditions. XPS spectra evolution, as a traditional source of information on phase composition, was complemented by the possibility to estimate the morphology and crystal field splitting of formed precipitates. Intensity fluctuations observed for O1s, Si 2p, Ti2p spectra were accompanied by crystal field splitting in Ti2p and on second derivatives of O1s. These fluctuations were followed by noticeable changes in the vicinity of band gap indicating possible Mott metal-insulator transitions.

  2. 13C NMR and XPS characterization of anion adsorbent with quaternary ammonium groups prepared from rice straw, corn stalk and sugarcane bagasse

    NASA Astrophysics Data System (ADS)

    Cao, Wei; Wang, Zhenqian; Zeng, Qingling; Shen, Chunhua

    2016-12-01

    Despite amino groups modified crop straw has been intensively studied as new and low-cost adsorbent for removal of anionic species from water, there is still a lack of clear characterization for amino groups, especially quaternary ammonium groups in the surface of crop straw. In this study, we used 13C NMR and XPS technologies to characterize adsorbents with quaternary ammonium groups prepared from rice straw, corn stalk and sugarcane bagasse. 13C NMR spectra clearly showed the presence of quaternary ammonium groups in lignocelluloses structure of modified crop straw. The increase of nitrogen observed in XPS survey spectra also indicated the existence of quaternary ammonium group in the surface of the adsorbents. The curve fitting of high-resolution XPS N1s and C1s spectra were conducted to probe the composition of nitrogen and carbon contained groups, respectively. The results showed the proportion of quaternary ammonium group significantly increased in the prepared adsorbent's surface that was dominated by methyl/methylene, hydroxyl, quaternary ammonium, ether and carbonyl groups. This study proved that 13C NMR and XPS could be successfully utilized for characterization of quaternary ammonium modified crop straw adsorbents.

  3. Rotationally resolved S1<--S0 electronic spectra of fluorene, carbazole, and dibenzofuran: Evidence for Herzberg-Teller coupling with the S2 state

    NASA Astrophysics Data System (ADS)

    Yi, John T.; Alvarez-Valtierra, Leonardo; Pratt, David W.

    2006-06-01

    Rotationally resolved fluorescence excitation spectra of the S1←S0 origin bands and higher vibronic bands of fluorene (FLU), carbazole (CAR), and dibenzofuran (DBF) have been observed and assigned. Analyses of these data show that replacement of the CH2 group in FLU with a NH group in CAR and an O atom in DBF produces only localized changes in structure, in the ground state. But the three molecules exhibit different changes in geometry when they are excited by light. The S1 states of the three molecules also are electronically very different. The S1←S0 transition moments of CAR and DBF are parallel to the C2 symmetry axis whereas the corresponding transition moment in FLU is perpendicular to this axis. Herzberg-Teller coupling involving the S2 state also has been observed in the spectra of higher vibronic bands of CAR and DBF. Possible reasons for these behaviors are discussed.

  4. Formation of hydroxyl and water layers on MgO films studied with ambient pressure XPS

    NASA Astrophysics Data System (ADS)

    Newberg, John T.; Starr, David E.; Yamamoto, Susumu; Kaya, Sarp; Kendelewicz, Tom; Mysak, Erin R.; Porsgaard, Soeren; Salmeron, Miquel B.; Brown, Gordon E., Jr.; Nilsson, Anders; Bluhm, Hendrik

    2011-01-01

    To understand the interaction of water with MgO(100), a detailed quantitative assessment of the interfacial chemistry is necessary. We have used ambient pressure X-ray photoelectron spectroscopy (XPS) to measure molecular (H 2O) and dissociative (OH) water adsorption on a 4 monolayer (ML) thick MgO(100)/Ag(100) film under ambient conditions. Since the entire 4 ML metal oxide (Ox) film is probed by XPS, the reaction of the MgO film with water can be quantitatively studied. Using a multilayer model (Model 1) that measures changes in Ox thickness from O 1s (film) and Ag 3d (substrate) spectra, it is shown that the oxide portion of the MgO film becomes thinner upon hydroxylation. A reaction mechanism is postulated in which the top-most layer of MgO converts to Mg(OH) 2 upon dissociation of water. Based on this mechanism a second model (Model 2) is developed to calculate Ox and OH thickness changes based on OH/Ox intensity ratios from O 1s spectra measured in situ, with the known initial Ox thickness prior to hydroxylation. Models 1 and 2 are applied to a 0.15 Torr isobar experiment, yielding similar results for H 2O, OH and Ox thickness changes as a function of relative humidity.

  5. Formation of Hydroxyl and Water Layers on MgO Films Studied with Ambient Pressure XPS

    SciTech Connect

    Newberg, J.T.; Starr, D.; Yamamoto, S.; Kaya, S.; Kendelewicz, T.; Mysak, E.R.; Porsgaard, S.; Salmeron, M.B.; Brown Jr., G.E.; Nilsson, A.; Bluhm, H.

    2011-01-01

    To understand the interaction of water with MgO(100), a detailed quantitative assessment of the interfacial chemistry is necessary. We have used ambient pressure X-ray photoelectron spectroscopy (XPS) to measure molecular (H{sub 2}O) and dissociative (OH) water adsorption on a 4 monolayer (ML) thick MgO(100)/Ag(100) film under ambient conditions. Since the entire 4 ML metal oxide (Ox) film is probed by XPS, the reaction of the MgO film with water can be quantitatively studied. Using a multilayer model (Model 1) that measures changes in Ox thickness from O 1s (film) and Ag 3d (substrate) spectra, it is shown that the oxide portion of the MgO film becomes thinner upon hydroxylation. A reaction mechanism is postulated in which the top-most layer of MgO converts to Mg(OH)2 upon dissociation of water. Based on this mechanism a second model (Model 2) is developed to calculate Ox and OH thickness changes based on OH/Ox intensity ratios from O 1s spectra measured in situ, with the known initial Ox thickness prior to hydroxylation. Models 1 and 2 are applied to a 0.15 Torr isobar experiment, yielding similar results for H{sub 2}O, OH and Ox thickness changes as a function of relative humidity.

  6. Experimental and ab-initio calculated vcd spectra of the first OH-stretching overtone of (1R)-(-) and (1S)-(+)-endo-BORNEOL.

    PubMed

    Gangemi, Fabrizio; Gangemi, Roberto; Longhi, Giovanna; Abbate, Sergio

    2009-04-21

    The near infrared (NIR) absorption and NIR-vibrational circular dichroism (NIR-VCD) spectra of dilute solutions of the two enantiomers of endo-borneol have been measured in the first OH-stretching overtone region (1600-1300 nm). By density functional theory (DFT) we calculate mechanical parameters, i.e. the harmonic mechanical frequency and the anharmonicity constant for the OH stretching, and anharmonic electrical parameters; i.e. the dependence on OH-bond length of atomic polar tensors and atomic axial tensors. We evaluate transition integrals for the calculations of rotational and dipole strengths by Morse anharmonic wavefunctions depending on mechanical harmonic frequencies and mechanical anharmonicity parameters that are calculated ab initio. Experimental and calculated spectra compare quite well and this fact allows us to associate differently signed NIR-VCD features with different conformational states of the OH-bond. Absorption features for the fundamental and for the second overtone of the OH stretching are also compared with experiment.

  7. Quantum mechanics/molecular mechanics modeling of photoelectron spectra: the carbon 1s core-electron binding energies of ethanol-water solutions.

    PubMed

    Löytynoja, T; Niskanen, J; Jänkälä, K; Vahtras, O; Rinkevicius, Z; Ågren, H

    2014-11-20

    Using ethanol-water solutions as illustration, we demonstrate the capability of the hybrid quantum mechanics/molecular mechanics (QM/MM) paradigm to simulate core photoelectron spectroscopy: the binding energies and the chemical shifts. An integrated approach with QM/MM binding energy calculations coupled to preceding molecular dynamics sampling is adopted to generate binding energies averaged over the solute-solvent configurations available at a particular temperature and pressure and thus allowing for a statistical assessment with confidence levels for the final binding energies. The results are analyzed in terms of the contributions in the molecular mechanics model-electrostatic, polarization, and van der Waals-with atom or bond granulation of the corresponding MM charge and polarizability force-fields. The role of extramolecular charge transfer screening of the core-hole and explicit hydrogen bonding is studied by extending the QM core to cover the first solvation shell. The results are compared to those obtained from pure electrostatic and polarizable continuum models. Particularly, the dependence of the carbon 1s binding energies with respect to the ethanol concentration is studied. Our results indicate that QM/MM can be used as an all-encompassing model to study photoelectron binding energies and chemical shifts in solvent environments.

  8. Structural and XPS studies of PSi/TiO2 nanocomposites prepared by ALD and Ag-assisted chemical etching

    NASA Astrophysics Data System (ADS)

    Iatsunskyi, Igor; Kempiński, Mateusz; Nowaczyk, Grzegorz; Jancelewicz, Mariusz; Pavlenko, Mykola; Załęski, Karol; Jurga, Stefan

    2015-08-01

    PSi/TiO2 nanocomposites fabricated by atomic layer deposition (ALD) and metal-assisted chemical etching (MACE) were investigated. The morphology and phase structure of PSi/TiO2 nanocomposites were studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) with an energy dispersive X-ray spectroscopy (EDX) and Raman spectroscopy. The mean size of TiO2 nanocrystals was determined by TEM and Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical elemental composition by observing the behavior of the Ti 2p, O 1s and Si 2p lines. TEM, Raman spectroscopy and XPS binding energy analysis confirmed the formation of TiO2 anatase phase inside the PSi matrix. The XPS valence band analysis was performed in order to investigate the modification of PSi/TiO2 nanocomposites electronic structure. Surface defects states of Ti3+ at PSi/TiO2 nanocomposites were identified by analyzing of XPS valence band spectra.

  9. In-situ NAP XPS studies of dissociative water adsorption on GaAs(100) surfaces

    NASA Astrophysics Data System (ADS)

    Ptasinska, Sylwia; Zhang, Xueqiang

    2014-03-01

    In current semiconductor-based technology it is important to design and fabricate new materials in order to achieve specific well-defined properties and functionalities. Before such systems can be applied they first need to be understood, refined and controlled. Therefore, a basic knowledge about molecule/semiconductor surface interfaces is essential. In the present work dissociative water adsorption on the GaAs(100) surface is monitored using X-ray Photoelectron Spectroscopy (XPS) performed in situ under near ambient conditions. Firstly, the crystal surface is exposed to water vapor pressures ranging from UHV to 0.5 kPa. At elevated pressures an increase of oxygenation and hydroxylation of Ga surface atoms has been observed in the Ga2p XPS spectra. Moreover, intense signals obtained from molecularly adsorbed water molecules or water molecules adsorbed via hydrogen bond to surface OH groups have been also observed in the O1s spectra. Finally, the crystal surface is annealed up to 700 K at water vapor pressure of 0.01 kPa, which leads to desorption of physisorbed water molecules and further increase of surface oxidation. The research described herein was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Basic Energy Sciences, Office of Science, United States Department of Energy through grant number DE-FC02-04ER15533.

  10. XPS Determination of Uranium Oxidations States

    SciTech Connect

    Ilton, Eugene S.; Bagus, Paul S.

    2011-12-01

    This contribution is both a review of different aspects of the XPS spectra that can help one determine U oxidation states and a personal perspective on how to effectively model the XPS of complicated mixed valence U phases. After a discussion of the valence band, the focus lingers on the U4f region, where the use of binding energies, satellite structures, and peak shapes is discussed in some detail. Binding energies were shown to be very dependent on composition/structure and consequently unreliable guides to oxidation state, particularly where assignment of composition is difficult. Likewise, the spin orbit split 4f7/2 and 4f5/2 peak shapes do not carry significant information on oxidation states. In contrast, both satellite-primary peak binding energy separations, as well as intensities too lesser extent, are relatively insensitive to composition/structure within the oxide-hydroxide-hydrate system and can be used to both identify and help quantify U oxidation states in mixed valence phases. An example of the usefulness of the satellite structure in constraining the interpretation of a complex multivalence U compound is given.

  11. XPS Study of Sulfonated Polyaniline.

    DTIC Science & Technology

    1991-08-07

    WORK UMaT Arlington, VA 22203-17 14 ELEMENT NO. INO. NO. CCESSION No 11. TITLE (tinclude Security Clisification) "XPS STUDY OF SULFONATED POLYANILINE ...by block nvjmhet) FlIELD GROUP $u-GOP sulfonated polyaniline , x-ray photoelectron spectroscopy O(IPS) 19. ABSTRACT (Continue on reverse if nvessary...STUDY OF SULFONATED POLYANiLINE " by J. Yue, AJ. Epstein and A.G. MacDiarrnid Published in PMSE Preprints, (In Press 1991) University of Pennsylvania

  12. XPS characterization of naturally aged wood

    NASA Astrophysics Data System (ADS)

    Popescu, Carmen-Mihaela; Tibirna, Carmen-Mihaela; Vasile, Cornelia

    2009-12-01

    Wood deterioration over time (by a simultaneously biological, chemical or physical attack) is an inevitable continuous process in the environment. This process destroys all heritage resulting in a loss of valuable old wooden structures and their properties. What type of deterioration occurs and how these processes impact the wood are important questions that need consideration if old wooden structures are to be studied and properly preserved. X-ray photoelectron spectroscopy (XPS) was employed to analyze the undegraded (sound wood of ˜6 years) and degraded lime wood (˜150 years, ˜180 years, ˜250 years) from painting supports, differing in terms of the provenance, conservation status and environmental conditions of storage. Elaborated XPS analysis (comparison of C and O individual spectra, decomposition for each atomic component, calculation of O/C ratio) provided a view of the composition of the sample surfaces analyzed. On the basis of these results, it was confirmed that significant changes occurred in the first period of ageing, the ˜150 years lime wood sample having the highest percent of the carbon atoms and the lowest percentage of oxygen atoms and, respectively O/C ratio. According to our previous studies (X-ray diffraction, FTIR spectroscopy, analytical pyrolysis combined with gas chromatography/mass spectrometry and ESR-spectroscopy results), these features could be attributed to the fact that hemicelluloses and amorphous cellulose are degraded in time, whereas the crystalline fraction of cellulose decreases more slowly than the amorphous one. Consequently, the observation may be made that lignin is not so easily degraded under the environmental conditions where paintings are frequently exposed.

  13. XPS study of surface state of novel perovskite system Dy0.5Sr0.5Co0.8Fe0.2O3-δ as cathode for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Kautkar, Pranay R.; Acharya, Smita A.; Tumram, Priya V.; Deshpande, U. P.

    2016-05-01

    In the present attempt,novel perovskite oxide Dy0.5Sr0.5Co0.8Fe0.2O3-δ (DSCF) as cathode material has been synthesized by an Ethylene glycol-citrate combined sol-gel combustion route. Orthorhombic symmetry structure is confirmed by X-ray diffraction (XRD) and data is well fitted using Rietveld refinement by Full-Prof software suite. Chemical natureof surface of DSCF has been analyzed by using X-ray photoelectron spectroscopy (XPS). XPS result shows that Dy ions are in +3 oxidation state and Sr in +2 states. However Co2p and Fe2p spectra indicates partial change in oxidation state from Co3+/Fe3+ to Co4+/Fe4+. These attribute to develop active sites on the surface for oxygen ions. O1s XPS spectra shows two oxygen peaks relatedto lattice oxygen in perovskite and absorbed oxygen in oxygen vacancy are detected. O1s spectra demonstrate the existence of adsorbed oxygen species on the surface of DSCF oxide which is quite beneficial for intermediate temperature of Solid Oxide Fuel Cell.

  14. Morphology and Chemical Composition of soot particles emitted by Wood-burning Cook-Stoves: a HRTEM, XPS and Elastic backscattering Studies.

    NASA Astrophysics Data System (ADS)

    Carabali-Sandoval, G. A., Sr.; Castro, T.; Peralta, O.; De la Cruz, W.; Días, J.; Amelines, O.; Rivera-Hernández, M.; Varela, A.; Muñoz-Muñoz, F.; Policroniades, R.; Murillo, G.; Moreno, E.

    2014-12-01

    The morphology, microstructure and the chemical composition on surface of soot particles were studied by using high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and elastic backscattering spectrometry. In order to obtain freshly soot particles emitted by home-made wood-burning cook stoves, copper grids for Transmission Electron Microscope (TEM) were placed on the last two of an 8-stages MOUDI cascade impactor. The analysis of HRTEM micrographs revealed the nanostructure and the particle size of soot particles. The XPS survey spectra show a large carbon peak around 285 eV and the oxygen signal at 533 eV. Some differences observed in the carbon/oxygen (C/O) ratio of the particles probably depend on the combustion process efficiency of each cook-stove analyzed. The C-1s XPS spectra show an asymmetric broad peak and other with low intensity that corresponds to sp2 and sp3hybridization, which were fitted with a convolution using Gaussian functions. Elastic backscattering technique allows a chemical elemental analysis of samples and confirms the presence of C, O and Si observed by XPS. Additionally, the morphological properties of soot aggregates were analyzed calculating the border-based fractal dimension (Df). Particles exhibit complex shapes with high values of Df. Also, real-time absorption (σabs) and scattering (σsct) coefficients of fine (with aerodynamic diameter < 2.5 µm) soot particles were measured. The trend in σabs and σsct indicate that the cooking process has two important combustion stages which varied in its flaming strength, being vigorous in the first stage and soft in the second one.

  15. Samarium electrodeposited acetate and oxide thin films on stainless steel substrate characterized by XPS

    DOE PAGES

    Myhre, Kristian; Burns, Jonathan; Meyer, Harry; ...

    2016-06-01

    Characterization of a samarium thin film deposited on a stainless steel substrate using molecular electrodeposition was carried out using a Thermo Scientific K-Alpha X-ray photoelectron spectrometer. We studied two types of samarium electrodeposition samples, one as-deposited and one heated to 700 °C in an air flow. Survey scans include peaks coming from the stainless steel substrate, such as Fe and Cr. An X-ray photoelectron spectroscopy (XPS) survey spectrum, Sm 3d, C 1s, and O 1s narrow scans are shown. It was determined that the heating process decomposed the deposited Sm acetate to Sm2O3 using XPS.

  16. Differentiation of Calcium Carbonate Polymorphs by Surface Analysis Techniques – An XPS and TOF-SIMS study

    PubMed Central

    Ni, Ming; Ratner, Buddy D.

    2013-01-01

    Calcium carbonate has evoked interest owing to its use as a biomaterial, and for its potential in biomineralization. Three polymorphs of calcium carbonate, i.e. calcite, aragonite, and vaterite were synthesized. Three conventional bulk analysis techniques, Fourier transform infrared (FTIR), X-ray diffraction (XRD), and SEM, were used to confirm the crystal phase of each polymorphic calcium carbonate. Two surface analysis techniques, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (TOF-SIMS), were used to differentiate the surfaces of these three polymorphs of calcium carbonate. XPS results clearly demonstrate that the surfaces of these three polymorphs are different as seen in the Ca(2p) and O(1s) core-level spectra. The different atomic arrangement in the crystal lattice, which provides for a different chemical environment, can explain this surface difference. Principal component analysis (PCA) was used to analyze the TOF-SIMS data. Three polymorphs of calcium carbonate cluster into three different groups by PCA scores. This suggests that surface analysis techniques are as powerful as conventional bulk analysis to discriminate calcium carbonate polymorphs. PMID:25031482

  17. Amino acid-based ionic liquids: using XPS to probe the electronic environment via binding energies.

    PubMed

    Hurisso, Bitu Birru; Lovelock, Kevin R J; Licence, Peter

    2011-10-21

    Here we report the synthesis and characterisation by X-ray photoelectron spectroscopy (XPS) of eight high purity amino acid-based ionic liquids (AAILs), each containing the 1-octyl-3-methylimidazolium, [C(8)C(1)Im](+), as a standard reference cation. All expected elements were observed and the electronic environments of these elements identified. A fitting model for the carbon 1s region of the AAILs is reported; the C aliphatic component of the cation was used as an internal reference to obtain a series of accurate and reproducible binding energies. Comparisons are made between XP spectra of the eight AAILs and selected non-functionalised ionic liquids. 1-octyl-3-methylimidazolium acetate was also studied as a model of the carboxyl containing amino acid anion. The influence of anionic substituent groups on the measured binding energies of all elements is presented, and communication between anion and cation is investigated. This data is interpreted in terms of hard and soft anions and compared to the Kamlet-Taft hydrogen bond acceptor ability, β, for the ionic liquids. A linear correlation is presented which suggests that the functional side chain, or R group, of the amino acid has little impact upon the electronic environment of the charge-bearing moieties within the anions and cations studied.

  18. sp2/sp3 hybridization ratio in amorphous carbon from C 1s core-level shifts: X-ray photoelectron spectroscopy and first-principles calculation

    NASA Astrophysics Data System (ADS)

    Haerle, Rainer; Riedo, Elisa; Pasquarello, Alfredo; Baldereschi, Alfonso

    2002-01-01

    Using a combined experimental and theoretical approach, we address C 1s core-level shifts in amorphous carbon. Experimental results are obtained by x-ray photoelectron spectroscopy (XPS) and electron-energy-loss spectroscopy (EELS) on thin-film samples of different atomic density, obtained by a pulsed-laser deposition growth process. The XPS spectra are deconvoluted into two contributions, which are attributed to sp2- and sp3-hybridized atoms, respectively, separated by 0.9 eV, independent of atomic density. The sp3 hybridization content extracted from XPS is consistent with the atomic density derived from the plasmon energy in the EELS spectrum. In our theoretical study, we generate several periodic model structures of amorphous carbon of different densities applying two schemes of increasing accuracy in sequence. We first use a molecular-dynamics approach, based on an environmental-dependent tight-binding Hamiltonian to quench the systems from the liquid phase. The final model structures are then obtained by further atomic relaxation using a first-principles pseudopotential plane-wave approach within density-functional theory. Within the latter framework, we also calculate carbon 1s core-level shifts for our disordered model structures. We find that the shifts associated to threefold- and fourfold- coordinated carbon atoms give rise to two distinct peaks separated by about 1.0 eV, independent of density, in close agreement with experimental observations. This provides strong support for decomposing the XPS spectra into two peaks resulting from sp2- and sp3-hybridized atoms. Core-hole relaxations effects account for about 30% of the calculated shifts.

  19. Near-ambient pressure XPS of high-temperature surface chemistry in Sr2Co2O5 thin films

    DOE PAGES

    Hong, Wesley T.; Stoerzinger, Kelsey; Crumlin, Ethan J.; ...

    2016-02-11

    Transition metal perovskite oxides are promising electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells, but a lack of fundamental understanding of oxide surfaces impedes the rational design of novel catalysts with improved device efficiencies. In particular, understanding the surface chemistry of oxides is essential for controlling both catalytic activity and long-term stability. Thus, elucidating the physical nature of species on perovskite surfaces and their catalytic enhancement would generate new insights in developing oxide electrocatalysts. In this article, we perform near-ambient pressure XPS of model brownmillerite Sr2Co2O5 (SCO) epitaxial thin films with different crystallographic orientations. Detailed analysis of themore » Co 2p spectra suggests that the films lose oxygen as a function of temperature. Moreover, deconvolution of the O 1s spectra shows distinct behavior for (114)-oriented SCO films compared to (001)-oriented SCO films, where an additional bulk oxygen species is observed. These findings indicate a change to a perovskite-like oxygen chemistry that occurs more easily in (114) SCO than (001) SCO, likely due to the orientation of oxygen vacancy channels out-of-plane with respect to the film surface. This difference in surface chemistry is responsible for the anisotropy of the oxygen surface exchange coefficient of SCO and may contribute to the enhanced ORR kinetics of La0.8Sr0.2CoO3-δ thin films by SCO surface particles observed previously.« less

  20. XPS and bioactivity study of the bisphosphonate pamidronate adsorbed onto plasma sprayed hydroxyapatite coatings

    NASA Astrophysics Data System (ADS)

    McLeod, Kate; Kumar, Sunil; Smart, Roger St. C.; Dutta, Naba; Voelcker, Nicolas H.; Anderson, Gail I.; Sekel, Ron

    2006-12-01

    This paper reports the use of X-ray photoelectron spectroscopy (XPS) to investigate bisphosphonate (BP) adsorption onto plasma sprayed hydroxyapatite (HA) coatings commonly used for orthopaedic implants. BPs exhibit high binding affinity for the calcium present in HA and hence can be adsorbed onto HA-coated implants to exploit their beneficial properties for improved bone growth at the implant interface. A rigorous XPS analysis of pamidronate, a commonly used nitrogenous BP, adsorbed onto plasma sprayed HA-coated cobalt-chromium substrates has been carried out, aimed at: (a) confirming the adsorption of this BP onto HA; (b) studying the BP diffusion profile in the HA coating by employing the technique of XPS depth profiling; (c) confirming the bioactivity of the adsorbed BP. XPS spectra of plasma sprayed HA-coated discs exposed to a 10 mM aqueous BP solution (pamidronate) for periods of 1, 2 and 24 h showed nitrogen and phosphorous photoelectron signals corresponding to the BP, confirming its adsorption onto the HA substrate. XPS depth profiling of the 2 h BP-exposed HA discs showed penetration of the BP into the HA matrix to depths of at least 260 nm. The bioactivity of the adsorbed BP was confirmed by the observed inhibition of osteoclast (bone resorbing) cell activity. In comparison to the HA sample, the HA sample with adsorbed BP exhibited a 25-fold decrease in primary osteoclast cells.

  1. Generalized molybdenum oxide surface chemical state XPS determination via informed amorphous sample model

    NASA Astrophysics Data System (ADS)

    Baltrusaitis, Jonas; Mendoza-Sanchez, Beatriz; Fernandez, Vincent; Veenstra, Rick; Dukstiene, Nijole; Roberts, Adam; Fairley, Neal

    2015-01-01

    Accurate elemental oxidation state determination for the outer surface of a complex material is of crucial importance in many science and engineering disciplines, including chemistry, fundamental and applied surface science, catalysis, semiconductors and many others. X-ray photoelectron spectroscopy (XPS) is the primary tool used for this purpose. The spectral data obtained, however, is often very complex and can be subject to incorrect interpretation. Unlike traditional XPS spectra fitting procedures using purely synthetic spectral components, here we develop and present an XPS data processing method based on vector analysis that allows creating XPS spectral components by incorporating key information, obtained experimentally. XPS spectral data, obtained from series of molybdenum oxide samples with varying oxidation states and degree of crystallinity, were processed using this method and the corresponding oxidation states present, as well as their relative distribution was elucidated. It was shown that monitoring the evolution of the chemistry and crystal structure of a molybdenum oxide sample due to an invasive X-ray probe could be used to infer solutions to complex spectral envelopes.

  2. XPS Study of Some Dilute Magnetic Semiconductors

    NASA Astrophysics Data System (ADS)

    Singhal, R. K.; Sharma, S. C.; Jakhar, N.

    2011-10-01

    In search for room temperature ferromagnetism (RTFM) in nominally doped oxides like ZnO, CeO2, TiO2 etc., several research attempts have been made in recent years. Unfortunately, these could not reach definite conclusions owing to controversial reports and the mechanism of FM ordering continues to remain illusive. We have synthesized Cr and Ni doped (5% each) ZnO bulk samples and studied their structural, electronic and magnetic properties. The magnetization and x-ray photoelectron spectroscopic (XPS) studies on these samples are presented and the electronic structure findings are correlated with magnetic properties.

  3. Self-consistent modelling of X-ray photoelectron spectra from air-exposed polycrystalline TiN thin films

    NASA Astrophysics Data System (ADS)

    Greczynski, G.; Hultman, L.

    2016-11-01

    We present first self-consistent modelling of x-ray photoelectron spectroscopy (XPS) Ti 2p, N 1s, O 1s, and C 1s core level spectra with a cross-peak quantitative agreement for a series of TiN thin films grown by dc magnetron sputtering and oxidized to different extent by varying the venting temperature Tv of the vacuum chamber before removing the deposited samples. So-obtained film series constitute a model case for XPS application studies, where certain degree of atmosphere exposure during sample transfer to the XPS instrument is unavoidable. The challenge is to extract information about surface chemistry without invoking destructive pre-cleaning with noble gas ions. All TiN surfaces are thus analyzed in the as-received state by XPS using monochromatic Al Kα radiation (hν = 1486.6 eV). Details of line shapes and relative peak areas obtained from deconvolution of the reference Ti 2p and N 1 s spectra representative of a native TiN surface serve as an input to model complex core level signals from air-exposed surfaces, where contributions from oxides and oxynitrides make the task very challenging considering the influence of the whole deposition process at hand. The essential part of the presented approach is that the deconvolution process is not only guided by the comparison to the reference binding energy values that often show large spread, but in order to increase reliability of the extracted chemical information the requirement for both qualitative and quantitative self-consistency between component peaks belonging to the same chemical species is imposed across all core-level spectra (including often neglected O 1s and C 1s signals). The relative ratios between contributions from different chemical species vary as a function of Tv presenting a self-consistency check for our model. We propose that the cross-peak self-consistency should be a prerequisite for reliable XPS peak modelling as it enhances credibility of obtained chemical information, while relying

  4. A single-source precursor approach to solution processed indium arsenide thin films† †Electronic supplementary information (ESI) available: Table listing selected bond lengths and angles for InAs precursor complex. Cross-sectional SEM of InAs thin film. XPS depth profile spectra of InAs thin film. Valence band XPS of InAs thin film and standard. CCDC 1477895. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6tc02293f Click here for additional data file. Click here for additional data file.

    PubMed Central

    Marchand, Peter; Sathasivam, Sanjayan; Williamson, Benjamin A. D.; Pugh, David; Bawaked, Salem M.; Basahel, Sulaiman N.; Obaid, Abdullah Y.; Scanlon, David O.; Parkin, Ivan P.

    2016-01-01

    This paper reports the synthesis of the novel single-source precursor, [{(MeInAstBu)3}2(Me2InAs(tBu)H)2] and the subsequent first report of aerosol-assisted chemical vapour deposition of InAs thin films. Owing to the use of the single-source precursor, highly crystalline and stoichiometric films were grown at a relatively low deposition temperature of 450 °C. Core level XPS depth profiling studies showed some partial oxidation of the film surface, however this was self-limiting and disappeared on etch profiles. Valence band XPS analysis matched well with the simulated density of state spectrum. Hall effect measurements performed on the films showed that the films were n-type with promising resistivity (3.6 × 10–3 Ω cm) and carrier mobility (410 cm2 V–1 s–1) values despite growth on amorphous glass substrates. PMID:27774150

  5. Samarium electrodeposited acetate and oxide thin films on stainless steel substrate characterized by XPS

    SciTech Connect

    Myhre, Kristian; Burns, Jonathan; Meyer, Harry; Sims, Nathan; Boll, Rose

    2016-06-01

    Characterization of a samarium thin film deposited on a stainless steel substrate using molecular electrodeposition was carried out using a Thermo Scientific K-Alpha X-ray photoelectron spectrometer. We studied two types of samarium electrodeposition samples, one as-deposited and one heated to 700 °C in an air flow. Survey scans include peaks coming from the stainless steel substrate, such as Fe and Cr. An X-ray photoelectron spectroscopy (XPS) survey spectrum, Sm 3d, C 1s, and O 1s narrow scans are shown. It was determined that the heating process decomposed the deposited Sm acetate to Sm2O3 using XPS.

  6. Structural, magnetic and XPS studies of Sn0.95Co0.05O2-0.05 and Sn0.95Fe0.05O2-0.05 nanoparticles

    NASA Astrophysics Data System (ADS)

    Kaur, Jasneet; Sahni, Kunal; Kumar, Vikas; Thakur, Kartik; Kotnala, R. K.; Verma, Kuldeep Chand

    2013-02-01

    Structural, microstructural, X-ray photoemission spectra (XPS) and magnetic properties of transition metal ion [5 mol% of Co (SC5) and Fe (SF5)]-doped SnO2 nanoparticles have been studied. The SC5 and SF5 nanoparticles were synthesized by a chemical route using polyvinyl alcohol as surfactant. The doped SnO2 crystallites were found to exhibit a tetragonal rutile structure and the average grains size was measured by the Scherer relation of X-ray diffraction. Transmission electron micrographs showed that the average grain size of SC5 is smaller than SF5. SC5 nanoparticles showed strong ferromagnetic behaviour but SF5 exhibited an F-centre exchange (FCE) mechanism. Temperature-dependent magnetization showed the values of phase transition temperature. XPS confirmed the presence of Sn-O-Co and Sn-O-Fe bonds in these SC5 and SF5 nanoparticles. The oxidation states of Sn, Co and Fe were found to be +4, +2 and +2, respectively, while the core level XPS peaks of Sn 3d, O 1s, Co 2p and Fe 2p were analyzed.

  7. XPS study on silica bismuthate glasses and glass ceramics

    NASA Astrophysics Data System (ADS)

    Simon, V.; Todea, M.; Takács, A. F.; Neumann, M.; Simon, S.

    2007-01-01

    X-ray photoelectron spectroscopy (XPS) was used to evidence the effect of the Bi 2O 3 to SiO 2 ratio and of partial crystallisation on the electronic charge density around the atoms entering silica-bismuthate glasses of nominal composition 0.01Fe 2O 3ṡ0.99[ xSiO 2ṡ(100- x)Bi 2O 3] with 10≤x≤60 mol%. The core level spectra show significant composition dependent changes in binding energy, and the full width at half maximum of photoelectron peaks both of cations and of oxygen atoms. The analysis reveals changes in electron density correlated with the ionic and covalent character of the samples. The shift in binding energy suggests charge transfer from silicon and oxygen atoms to bismuth atoms. Contrary to the expected behaviour in conventional silicate oxide systems, the results indicate an increase of ionicity for silicon and of covalency for bismuth atoms. The same evolution of ionicity/covalency is observed after partial crystallisation.

  8. XPS study of reductive dissolution of birnessite by oxalate: Rates and mechanistic aspects of dissolution and redox processes

    SciTech Connect

    Banerjee, D.; Nesbitt, H.W.

    1999-10-01

    Reductive dissolution of synthetic 7{angstrom}-birnessite [MnO{sub 1.7}(OH){sub 0.25} or MnO{sub 1.95}] by Na-oxalate produces a Mn(III) intermediate reaction product (here represented as MnOOH) which subsequently reacts with sorbed (COO){sub 2}{sup {minus}2} to form an unreactive Mn(III)-oxalate surface complex at the solution-mineral interface. X-ray Photoelectron Spectroscopy (XPS) results from Mn2p{sub 3/2}, C1s and O1s spectra of reacted surfaces reveal that initially rapid production of CO{sub 2} results in accumulation of CO{sub 2} at the reaction interface. After about 15 min, the reaction rate decreases to the point where CO{sub 2} desorption keeps pace with accumulation. Surface concentrations of CO{sub 2} suggest that the rate of CO{sub 2} production decreases with time, until after 10 hr of reaction, it is undetectable. Reduction of Mn(IV) to Mn(III) suggests that the MnO{sub 2}-oxalate redox reaction proceeds as a transfer of one electron per metal center. There is no XPS evidence for reduction of Mn(III) from birnessite to Mn(II) in the presence of oxalate. Although this reaction proceeds in presence of arsenite, it is inhibited by oxalate, probably through formation of a strong Mn(III)-oxalate surface complex (either monodentate or bidentate). This hypothesis is consistent with Mn{sup 3+} (aq) stabilization by oxalate in aqueous solutions. Further study using X-ray absorption spectroscopy (XAS) is required for a better understanding of the structure of the surface complexes. Rate of release of soluble Mn(II) to dilute oxalate solutions (5 x 10{sup {minus}4} M) is lower by an order of magnitude than the rate of release to aerated, distilled water at similar pH. Apparently, the process of proton-promoted dissolution of the soluble Mn(II) component of birnessite in distilled water is impeded by the addition of oxalate, probably by formation of a binuclear, bidentate surface complex between Mn(II, III) and adsorbed oxalate ions.

  9. Chemical and morphological characterization of TSP and PM2.5 by SEM-EDS, XPS and XRD collected in the metropolitan area of Monterrey, Mexico

    NASA Astrophysics Data System (ADS)

    González, Lucy T.; Rodríguez, F. E. Longoria; Sánchez-Domínguez, M.; Leyva-Porras, C.; Silva-Vidaurri, L. G.; Acuna-Askar, Karim; Kharisov, B. I.; Villarreal Chiu, J. F.; Alfaro Barbosa, J. M.

    2016-10-01

    Total suspended particles (TSP) and particles smaller than 2.5 μm (PM2.5) were collected at four sites in the metropolitan area of Monterrey (MAM) in Mexico. The samples were characterized by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM). In order to determine the possible sources of emissions of atmospheric particulate matter, a principal component analysis (PCA) was performed. The XRD results showed that the major crystalline compounds found in the TPS were CaCO3 and SiO2; while in the PM2.5 CaSO4 was found. The XPS analysis showed that the main elements found on the surface of the particles were C, O, Si, Ca, S, and N. The deconvolution carried out on the high-resolution spectra for C1s, S2p and N1s, showed that the aromatics, sulfates and pyrrolic-amides were the main groups contributing to the signal of these elements, respectively. The C-rich particles presented a spherical morphology, while the Ca- and Si-based particles mostly showed a prismatic shape. The PCA analysis together with the results obtained from the characterization techniques, suggested that the main contributors to the CaCO3 particles collected in the PM were most probably produced and emitted into the atmosphere by local construction industries and exploitation of rich-deposits of calcite. Meanwhile, the SiO2 found in the MAM originated from the suspension of geological material abundant in the region, and the carbon particles were mainly produced by the combustion of fossil fuels.

  10. Dynamic XPS measurements of ultrathin polyelectrolyte films containing antibacterial Ag–Cu nanoparticles

    SciTech Connect

    Taner-Camcı, Merve; Suzer, Sefik

    2014-03-15

    Ultrathin films consisting of polyelectrolyte layers prepared by layer-by-layer deposition technique and containing also Ag and Cu nanoparticles exhibit superior antibacterial activity toward Escherichia coli. These films have been investigated with XPS measurements under square wave excitation at two different frequencies, in order to further our understanding about the chemical/physical nature of the nanoparticles. Dubbed as dynamical XPS, such measurements bring out similarities and differences among the surface structures by correlating the binding energy shifts of the corresponding XPS peaks. Accordingly, it is observed that the Cu2p, Ag3d of the metal nanoparticles, and S2p of cysteine, the stabilizer and the capping agent, exhibit similar shifts. On the other hand, the C1s, N1s, and S2p peaks of the polyelectrolyte layers shift differently. This finding leads us the claim that the Ag and Cu atoms are in a nanoalloy structure, capped with cystein, as opposed to phase separated entities.

  11. Gold/silver core-shell 20 nm nanoparticles extracted from citrate solution examined by XPS

    SciTech Connect

    Engelhard, Mark H.; Smith, Jordan N.; Baer, Donald R.

    2016-06-01

    Silver nanoparticles of many types are widely used in consumer and medical products. The surface chemistry of particles and the coatings that form during synthesis or use in many types of media can significantly impact the behaviors of particles including dissolution, transformation and biological or environmental impact. Consequently it is useful to be able to extract information about the thickness of surface coatings and other attributes of nanoparticles produced in a variety of ways. It has been demonstrated that X-ray Photoelectron Spectroscopy (XPS) can be reliably used to determine the thickness of organic and other nanoparticles coatings and shells. However, care is required to produce reliable and consistent information. Here we report the XPS spectra from gold/silver core-shell nanoparticles of nominal size 20 nm removed from a citrate saturated solution after one and two washing cycles. The Simulation of Electron Spectra for Surface Analysis (SESSA) program had been used to model peak amplitudes to obtain information on citrate coatings that remain after washing and demonstrate the presence of the gold core. This data is provided so that others can compare use of SESSA or other modeling approaches to quantify the nature of coatings to those already published and to explore the impacts particle non-uniformities on XPS signals from core-shell nanoparticles.

  12. Combined DFT and XPS investigation of iodine anions adsorption on the sulfur terminated (001) chalcopyrite surface

    NASA Astrophysics Data System (ADS)

    Li, Kui; Zhao, Yaolin; Zhang, Peng; He, Chaohui; Deng, Jia; Ding, Shujiang; Shi, Weiqun

    2016-12-01

    The adsorption of iodine anions (iodide and iodate) on the sulfur terminated (001) chalcopyrite surface has been systematically investigated combining first-principles calculations based on density functional theory (DFT) with X-ray photoelectron spectroscopy (XPS) measurements. Based on the total energy calculations and geometric optimization, the thermodynamically preferred site was copper atom for iodide adsorption and iron atom for iodate adsorption, respectively. In the case of Cu site mode, the iodate underwent a dissociative adsorption, where one Isbnd O bond of iodate ion was broken and the dissociative oxygen atom adsorbed on the adjacent sulphur site. Projected density of states (PDOS) analysis further clarified the interaction mechanism between active sites of chalcopyrite surface and adsorbates. In addition, full-range XPS spectra qualitatively revealed the presence of iodine on chalcopyrite surface. High resolution XPS spectra of the I 3d peaks after adsorption verified the chemical environment of iodine. The binding energies of 618.8 eV and 623.5 eV for I 3d5/2 peaks unveiled that the adsorption of iodide and iodate ions on copper-iron sulfide minerals was the result of formation of low solubility metal iodides precipitate. Also two I 3d peaks with low intensity around 618 eV and 630 eV might be related to the inorganic reduction of iodate to iodide by reducing S2- ion of chalcopyrite.

  13. Near-ambient pressure XPS of high-temperature surface chemistry in Sr2Co2O5 thin films

    SciTech Connect

    Hong, Wesley T.; Stoerzinger, Kelsey; Crumlin, Ethan J.; Mutoro, Eva; Jeen, Hyoung Jeen; Lee, Ho Nyung; Shao-Horn, Yang

    2016-02-11

    Transition metal perovskite oxides are promising electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells, but a lack of fundamental understanding of oxide surfaces impedes the rational design of novel catalysts with improved device efficiencies. In particular, understanding the surface chemistry of oxides is essential for controlling both catalytic activity and long-term stability. Thus, elucidating the physical nature of species on perovskite surfaces and their catalytic enhancement would generate new insights in developing oxide electrocatalysts. In this article, we perform near-ambient pressure XPS of model brownmillerite Sr2Co2O5 (SCO) epitaxial thin films with different crystallographic orientations. Detailed analysis of the Co 2p spectra suggests that the films lose oxygen as a function of temperature. Moreover, deconvolution of the O 1s spectra shows distinct behavior for (114)-oriented SCO films compared to (001)-oriented SCO films, where an additional bulk oxygen species is observed. These findings indicate a change to a perovskite-like oxygen chemistry that occurs more easily in (114) SCO than (001) SCO, likely due to the orientation of oxygen vacancy channels out-of-plane with respect to the film surface. This difference in surface chemistry is responsible for the anisotropy of the oxygen surface exchange coefficient of SCO and may contribute to the enhanced ORR kinetics of La0.8Sr0.2CoO3-δ thin films by SCO surface particles observed previously.

  14. Electronic structure of β-RbNd(MoO4)2 by XPS and XES

    NASA Astrophysics Data System (ADS)

    Atuchin, V. V.; Khyzhun, O. Y.; Chimitova, O. D.; Molokeev, M. S.; Gavrilova, T. A.; Bazarov, B. G.; Bazarova, J. G.

    2015-02-01

    β-RbNd(MoO4)2 microplates have been prepared by the multistage solid state synthesis method. The phase composition and micromorphology of the final product have been evaluated by XRD and SEM methods. The electronic structure of β-RbNd(MoO4)2 molybdate has been studied employing the X-ray photoelectron spectroscopy (XPS) and X-ray emission spectroscopy (XES). For the molybdate, the XPS core-level and valence-band spectra, as well as XES bands representing energy distribution of the Mo 4d- and O 2p-like states, have been measured. It has been established that the O 2p-like states contribute mainly to the upper portion of the valence band with also significant contributions throughout the whole valence-band region. The Mo 4D-like states contribute mainly to a lower valence band portion.

  15. RECENT XPS STUDIES OF THE EFFECT OF PROCESSING ON NB SRF SURFACES

    SciTech Connect

    Hui Tian; Binping Xiao; Michael Kelley; Charles Reece; A. Demasi; L. Pipe; Kevin Smith

    2008-02-12

    XPS studies have consistently shown that Nb surfaces for SRF chiefly comprise of a few nm of Nb2O5 on top of Nb metal, with minor amounts of Nb sub-oxides. Nb samples after BCP/EP treatment with post-baking at the various conditions have been examined by using synchrotron based XPS. Despite the confounding influence of surface roughness, certain outcomes are clear. Lower-valence Nb species are always and only associated with the metal/oxide interface, but evidence for an explicit layer structure or discrete phases is lacking. Post-baking without air exposure shows decreased oxide layer thickness and increased contribution from lower valence species, but spectra obtained after subsequent air exposure cannot be distinguished from those obtained prior to baking, though the SRF performance improvement remains.

  16. A theoretical study of the XP and NEXAFS spectra of alanine: gas phase molecule, crystal, and adsorbate at the ZnO(10 ̅10) surface.

    PubMed

    Gao, You Kun; Traeger, Franziska; Kotsis, Konstantinos; Staemmler, Volker

    2011-06-14

    The adsorption of alanine on the mixed-terminated ZnO(10 ̅10) surface is studied by means of quantum-chemical ab initio calculations. Using a finite cluster model and the adsorption geometry as obtained both by periodic CPMD and embedded cluster calculations, the C1s, N1s and O1s X-ray photoelectron spectra (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectra are calculated for single alanine molecules on ZnO(10 ̅10). These spectra are compared with the spectra calculated for alanine in the gas phase and in its crystalline form and with experimental XPS and NEXAFS data for the isolated alanine molecule and for alanine adsorbed on ZnO(10 ̅10) at multilayer and monolayer coverage. The excellent agreement between the experimental and calculated XP and NEXAFS spectra confirms the calculated adsorption geometry: A single alanine molecule is bound to ZnO(10 ̅10) in a dissociated bidentate form with the two O atoms of the acid group bound to two Zn atoms of the surface and the proton transferred to one O atom of the surface. Other possible structures, such as adsorption of alanine in one of its neutral or zwitterionic forms in which the proton of the -COOH group remains at this group or is transferred to the amino group, can be excluded since they would give rise to quite different XP spectra. In the multilayer coverage regime, on the other hand, alanine is in its crystalline form as is also shown by the analysis of the XP spectra.

  17. ELS and XPS study of Pd/PdO methane oxidation catalysts

    NASA Astrophysics Data System (ADS)

    Hoflund, Gar B.; Hagelin, Helena A. E.; Weaver, Jason F.; Salaita, Ghaleb N.

    2003-01-01

    Electron energy loss spectra (ELS) and X-ray photoelectron spectroscopy (XPS) data obtained from palladium powder catalysts used for complete methane oxidation have been obtained in this study in order to gain information about the Pd chemical state. Metallic Pd and PdO yield significantly different ELS spectra making ELS useful for chemical-state determination. Palladium(II) oxide is readily detected by the presence of an energy loss feature at 3.7 eV. Species distribution in the direction normal to the surface can be determined using ELS by varying the primary beam energy. Both XPS and ELS data indicate that PdO forms during reaction, and the ELS data demonstrate that PdO forms as a film over the Pd metal. If any Pd metal is present in the PdO film, it is there at levels below the detection limit of ELS. These observations have important consequences with regard to the mechanism of methane oxidation over Pd-containing catalysts. Hydrous and anhydrous palladium(II) oxides have significantly different energy loss features in the low loss-energy region of the ELS spectra. ELS features attributed to water are observed at 5.5-6.5 and 8 eV for hydrous palladium(II) oxide.

  18. Theoretical modeling of the uranium 4f XPS for U(VI) and U(IV) oxides

    SciTech Connect

    Bagus, Paul S.; Nelin, Connie J.; Ilton, Eugene S.

    2013-12-28

    A rigorous study is presented of the physical processes related to X-Ray photoelectron spectroscopy, XPS, in the 4f level of U oxides, which, as well as being of physical interest in themselves, are representative of XPS in heavy metal oxides. In particular, we present compelling evidence for a new view of the screening of core-holes that extends prior understandings. Our analysis of the screening focuses on the covalent mixing of high lying U and O orbitals as opposed to the, more common, use of orbitals that are nominally pure U or pure O. It is shown that this covalent mixing is quite different for the initial and final, core-hole, configurations and that this difference is directly related to the XPS satellite intensity. Furthermore, we show that the high-lying U d orbitals as well as the U(5f) orbital may both contribute to the core-hole screening, in contrast with previous work that has only considered screening through the U(5f) shell. The role of modifying the U-O interaction by changing the U-O distance has been investigated and an unexpected correlation between U-O distance and XPS satellite intensity has been discovered. The role of flourite and octahedral crystal structures for U(IV) oxides has been examined and relationships established between XPS features and the covalent interactions in the different structures. The physical views of XPS satellites as arising from shake processes or as arising from ligand to metal charge transfers are contrasted; our analysis provides strong support that shake processes give a more fundamental physical understanding than charge transfer. Our theoretical studies are based on rigorous, strictly ab initio determinations of the electronic structure of embedded cluster models of U oxides with formal U(VI) and U(IV) oxidation states. Our results provide a foundation that makes it possible to establish quantitative relationships between features of the XPS spectra and materials properties.

  19. Theoretical modeling of the uranium 4f XPS for U(VI) and U(IV) oxides.

    PubMed

    Bagus, Paul S; Nelin, Connie J; Ilton, Eugene S

    2013-12-28

    A rigorous study is presented of the physical processes related to X-Ray photoelectron spectroscopy, XPS, in the 4f level of U oxides, which, as well as being of physical interest in themselves, are representative of XPS in heavy metal oxides. In particular, we present compelling evidence for a new view of the screening of core-holes that extends prior understandings. Our analysis of the screening focuses on the covalent mixing of high lying U and O orbitals as opposed to the, more common, use of orbitals that are nominally pure U or pure O. It is shown that this covalent mixing is quite different for the initial and final, core-hole, configurations and that this difference is directly related to the XPS satellite intensity. Furthermore, we show that the high-lying U d orbitals as well as the U(5f) orbital may both contribute to the core-hole screening, in contrast with previous work that has only considered screening through the U(5f) shell. The role of modifying the U-O interaction by changing the U-O distance has been investigated and an unexpected correlation between U-O distance and XPS satellite intensity has been discovered. The role of flourite and octahedral crystal structures for U(IV) oxides has been examined and relationships established between XPS features and the covalent interactions in the different structures. The physical views of XPS satellites as arising from shake processes or as arising from ligand to metal charge transfers are contrasted; our analysis provides strong support that shake processes give a more fundamental physical understanding than charge transfer. Our theoretical studies are based on rigorous, strictly ab initio determinations of the electronic structure of embedded cluster models of U oxides with formal U(VI) and U(IV) oxidation states. Our results provide a foundation that makes it possible to establish quantitative relationships between features of the XPS spectra and materials properties.

  20. Chemical Visualization of a GaN p-n junction by XPS

    PubMed Central

    Caliskan, Deniz; Sezen, Hikmet; Ozbay, Ekmel; Suzer, Sefik

    2015-01-01

    We report on an operando XPS investigation of a GaN diode, by recording the Ga2p3/2 peak position under both forward and reverse bias. Areal maps of the peak positions under reverse bias are completely decoupled with respect to doped regions and allow a novel chemical visualization of the p-n junction in a 2-D fashion. Other electrical properties of the device, such as leakage current, resistivity of the domains are also tapped via recording line-scan spectra. Application of a triangular voltage excitation enables probing photoresponse of the device. PMID:26359762

  1. Organic adlayer on inorganic materials: XPS analysis selectivity to cope with adventitious contamination

    NASA Astrophysics Data System (ADS)

    Landoulsi, Jessem; Genet, Michel J.; Fleith, Sandrine; Touré, Yetioman; Liascukiene, Irma; Méthivier, Christophe; Rouxhet, Paul G.

    2016-10-01

    This work addresses the ubiquitous presence of organic contaminants at inorganic solid surfaces and the improvement of XPS analysis selectivity to cope with it. Water contact angle measurements showed that the adsorption of organic contaminants occurs readily in ambient air, and faster and more extensively under high vacuum. It is stronger on stainless steel (SS) compared to silica and is significantly reduced when SS is sterilized by autoclaving. The reliability of XPS data was evaluated (selectivity, precision, accuracy) by correlations between spectral data incorporating a large amount of results obtained with different XPS spectrometers on SS and glass samples cleaned in different ways and conditioned with several biomacromolecules. The methodology used allows a discrimination to be made between contaminants and deliberately adsorbed biomacromolecules, and offers perspectives for tracking the source of contamination. Furthermore, a discrimination can be made between oxygen from the organic adlayer and oxygen from the substrate, and the O 1s component above 532.0 eV observed for SS is shown to be due to organic contaminants rather than adsorbed water. This approach offers new perspectives to examine the interactions (displacement or not) between contaminants and compounds of interest, e.g. proteins, at the stage of the adsorption process.

  2. Energy Thresholds of DNA Damage Induced by UV Radiation: An XPS Study.

    PubMed

    Gomes, P J; Ferraria, A M; Botelho do Rego, A M; Hoffmann, S V; Ribeiro, P A; Raposo, M

    2015-04-30

    This work stresses on damage at the molecular level caused by ultraviolet radiation (UV) in the range from 3.5 to 8 eV, deoxyribonucleic acid (DNA) films observed by X-ray photoelectron spectroscopy (XPS). Detailed quantitative XPS analysis, in which all the amounts are relative to sodium-assumed not to be released from the samples, of the carbon, oxygen, and particularly, nitrogen components, reveals that irradiation leads to sugar degradation with CO-based compounds release for energies above 6.9 eV and decrease of nitrogen groups which are not involved in hydrogen bonding at energies above 4.2 eV. Also the phosphate groups are seen to decrease to energies above 4.2 eV. Analysis of XPS spectra allowed to conclude that the damage on bases peripheral nitrogen atoms are following the damage on phosphates. It suggests that very low kinetic energy photoelectrons are ejected from the DNA bases, as a result of UV light induced breaking of the phosphate ester groups which forms a transient anion with resonance formation and whereby most of the nitrogen DNA peripheral groups are removed. The degree of ionization of DNA was observed to increase with radiation energy, indicating that the ionized phosphate groups are kept unchanged. This result was interpreted by the shielding of phosphate groups caused by water molecules hydration near sodium atoms.

  3. The Effect of Thermal and Mechanical Treatments on Kaolinite: Characterization by XPS and IEP Measurements.

    PubMed

    Torres Sánchez RM; Basaldella; Marco

    1999-07-15

    The surface transformations induced on kaolinite by different thermal and mechanical treatments have been investigated by means of X-ray photoelectron spectroscopy (XPS), Bremsstrahlung induced Auger spectroscopy, and isoelectric point (IEP) measurements. Heating the kaolinite at temperatures between 500 and 750 degrees C results in the change of a substantial fraction of surface Al from octahedral to tetrahedral coordination, which we associate with the dehydroxylation of kaolinite. Heating at 900 and 980 degrees C brings about the development of an octahedral Al fraction which is associated with the formation of gamma-Al(2)O(3). The development of an Al tetrahedral component in the Al KLL spectra of the mechanically treated (ground) samples has been also observed. The Si/Al atomic ratio obtained by XPS in the thermally treated samples is the same as that shown by the original kaolinite. However, the XPS data show a clear reduction of the Si/Al atomic ratio in the mechanically treated samples, which suggests that the mechanical treatment has induced an Al enrichment of the kaolinite surface. The IEP values indicated a thermal transformation to metakaolinite and mullite with the increase of temperature (750 to 980 degrees C). The IEP change for the milled samples can be only explained by assuming a 30% kaolinite coating by the Al oxide neoformed by grinding. Copyright 1999 Academic Press.

  4. XPS characterization of polymer–monocalcium aluminate interface

    SciTech Connect

    Kalina, Lukáš Másilko, Jiří; Koplík, Jan; Šoukal, František

    2014-12-15

    The aim of this paper is the introduction of a sophisticated testing method, X-ray photoelectron spectroscopy (XPS), used to study the interface between the hydrated cement phase and polymer after mechanochemical activation, which is fundamental for the creation of macro-defect-free (MDF) composites. The XPS results clearly explain the hypothesis of a chemical reaction mechanism in the interphase regions affecting the final properties of the MDF materials.

  5. Thermal chemistry of copper acetamidinate atomic layer deposition precursors on silicon oxide surfaces studied by XPS

    SciTech Connect

    Yao, Yunxi; Zaera, Francisco

    2016-01-15

    The thermal surface chemistry of copper(I)-N,N′-di-sec-butylacetamidinate, [Cu({sup s}Bu-amd)]{sub 2}, a metalorganic complex recently proposed for the chemical-based deposition of copper films, has been characterized on SiO{sub 2} films under ultrahigh vacuum conditions by x-ray photoelectron spectroscopy (XPS). Initial adsorption at cryogenic temperatures results in the oxidation of the copper centers with Cu 2p{sub 3/2} XPS binding energies close to those seen for a +2 oxidation state, an observation that the authors interpret as the result of the additional coordination of oxygen atoms from the surface to the Cu atoms of the molecular acetamidinate dimer. Either heating to 300 K or dosing the precursor directly at that temperature leads to the loss of one of its two ligands, presumably via hydrogenation/protonation with a hydrogen/proton from a silanol group, or following a similar reaction on a defect site. By approximately 500 K the Cu 2p{sub 3/2}, C 1s, and N 1s XPS data suggest that the remaining acetamidinate ligand is displaced from the copper center and bonds to the silicon oxide directly, after which temperatures above 900 K need to be reached to promote further (and only partial) decomposition of those organic moieties. It was also shown that the uptake of the Cu precursor is self-limiting at either 300 or 500 K, although the initial chemistry is somewhat different at the two temperatures, and that the nature of the substrate also defines reactivity, with the thin native silicon oxide layer always present on Si(100) surfaces being less reactive than thicker films grown by evaporation, presumably because of the lower density of surface nucleation sites.

  6. Thermoresponsive gold nanoshell@mesoporous silica nano-assemblies: an XPS/NMR survey.

    PubMed

    Soulé, S; Allouche, J; Dupin, J-C; Courrèges, C; Plantier, F; Ojo, W-S; Coppel, Y; Nayral, C; Delpech, F; Martinez, H

    2015-11-21

    This work provides a detailed study on the physico-chemical characterization of a mechanized silver-gold alloy@mesoporous silica shell/pseudorotaxane nano-assembly using two main complementary techniques: XPS and NMR (liquid- and solid-state). The pseudorotaxane nanovalve is composed of a stalk (N-(6-aminohexyl)-aminomethyltriethoxysilane)/macrocycle (cucurbit[6]uril (CB6)) complex anchored to the silica shell leading to a silica/nanovalve hybrid organic-inorganic interface that has been fully characterized. The stalk introduction in the silica network was clearly demonstrated by XPS measurements, with the Si 2p peak shifting to lower energy after grafting, and through the analysis of the C 1s and N 1s core peaks, which indicated the presence of CB6 on the nanoparticle surface. For the first time, the complex formation on nanoparticles was proved by high speed (1)H MAS NMR experiments. However, these solid state NMR analyses have shown that the majority of the stalk does not interact with the CB6 macrocycle when formulated in powder after removing the solvent. This can be related to the large number of possible organizations and interactions between the stalk, the CB6 and the silica surface. These results highlight the importance of using a combination of adapted and complementary highly sensitive surface and volume characterization techniques to design tailor-made hybrid hierarchical structured nano-assemblies with controlled and efficient properties for potential biological purposes.

  7. Characterization of fossil remains using XRF, XPS and XAFS spectroscopies

    NASA Astrophysics Data System (ADS)

    Zougrou, I. M.; Katsikini, M.; Pinakidou, F.; Brzhezinskaya, M.; Papadopoulou, L.; Vlachos, E.; Tsoukala, E.; Paloura, E. C.

    2016-05-01

    Synchrotron radiation micro-X-Ray Fluorescence (μ-XRF), X-ray photoelectron (XPS) and X-ray Absorption Fine Structure (XAFS) spectroscopies are applied for the study of paleontological findings. More specifically the costal plate of a gigantic terrestrial turtle Titanochelon bacharidisi and a fossilized coprolite of the cave spotted hyena Crocuta crocuta spelaea are studied. Ca L 2,3-edge NEXAFS and Ca 2p XPS are applied for the identification and quantification of apatite and Ca containing minerals. XRF mapping and XAFS are employed for the study of the spatial distribution and speciation of the minerals related to the deposition environment.

  8. Excitation of XPS spectra from nanoscaled particles by local generation of x-rays

    SciTech Connect

    Mallinson, Christopher F.; Castle, James E.

    2015-09-15

    In preliminary work, the authors have shown that use of an aluminum substrate to support a distribution of copper particles enables their characteristic photoelectrons to be observed within the Auger electron spectrum generated by an incident electron beam. This observation raises the possibility of the use of chemical shifts and the corresponding Auger parameter to identify the chemical states present on the surface of individual submicrometer particles within a mixture. In this context, the technique has an advantage in that, unlike conventional Auger electron spectroscopy, the electron beam does not dwell on the particle but on the substrate adjacent to it. Given the importance, for both medical and toxicological reasons, of the surface composition of such particles, the authors have continued to explore the potential of this development. In this contribution, the authors show that proximal excitation of x-rays is equally successful with magnesium substrates. In some regions of the x-ray photoelectron spectrum, the much larger Auger peaks generated by the electron beam can cause inconvenient clustering of Auger and photoelectron peaks. As in conventional x-ray photoelectron spectroscopy, the ability to switch between Al and Mg sources is useful in such situations. In this context, the authors have extended the studies to iron particles where the authors show that use of Al or Mg substrates, as necessary, can make a contribution to clear identification of individual components in the Fe 2p peaks. For this development in electron spectroscopy to achieve its full potential, it is necessary to optimize the beam conditions used to generate the local x-ray to give good selectivity of a given particle. Measurements made in support of this will be given. Of greater concern is a possible problem of local heating associated with x-ray generation. The authors continue to explore this problem and report some progress in minimizing heating of the particle while maintaining the particle selectivity that is central to this exciting development.

  9. Comparative study of the native oxide on 316L stainless steel by XPS and ToF-SIMS

    SciTech Connect

    Tardio, Sabrina Abel, Marie-Laure; Castle, James E.; Watts, John F.; Carr, Robert H.

    2015-09-15

    The very thin native oxide film on stainless steel, of the order of 2 nm, is known to be readily modified by immersion in aqueous media. In this paper, X-ray photoelectron spectroscopy (XPS) and time of flight secondary ions mass spectrometry are employed to investigate the nature of the air-formed film and modification after water emersion. The film is described in terms of oxide, hydroxide, and water content. The preferential dissolution of iron is shown to occur on immersion. It is shown that a water absorbed layer and a hydroxide layer are present above the oxide-like passive film. The concentrations of water and hydroxide appear to be higher in the case of exposure to water. A secure method for the peak fitting of Fe2p and Cr2p XPS spectra of such films on their metallic substrates is described. The importance of XPS survey spectra is underlined and the feasibility of C{sub 60}{sup +} SIMS depth profiling of a thin oxide layer is shown.

  10. Elastic and inelastic contributions to the XPS photoelectron diffraction patterns of Ni(100) and NiO(100)

    NASA Astrophysics Data System (ADS)

    Steiner, P.; Straub, Th.; Reinert, Fr.; Zimmermann, R.; Hüfner, S.

    1993-07-01

    XPS spectra of Ni(100) and NiO(100) single crystals, measured as a function of the polar angle in the [100]-[010] emission plane, are successfully decomposed into their elastic (intrinsic spectrum) and inelastic contributions using the background subtraction procedure as proposed by Tougaard et al. [Phys. Rev. B 25 (1981) 4452; Surf. Interface Anal. 11 (1988) 453; J. Electron Spectrosc. Relat. Phenom. 52 (1990) 243], with an electron energy loss function deduced from experimental electron energy loss spectra. The inelastic background correction factor shows a diffraction pattern which anticorrelates nearly linearly to the photoelectron diffraction pattern of the intrinsic spectrum, that is its maxima and minima coincide with the minima and maxima of the latter. This behaviour can be described by a simple model, based on heuristic arguments on inelastic and elastic losses and "defocusing" due to multiple scattering along densely packed rows of atoms in the lattice. The consequence of different background subtraction procedures on the shape of the XPS diffraction pattern and for the quantification of XPS data is discussed.

  11. [An FTIR and XPS study of immobilization of chromium with fly ash based geopolymers].

    PubMed

    Liu, Si-Feng; Wang, Pei-Ming; Li, Zong-Jin; Lo, Irene M C

    2008-01-01

    Immobilization of Cr3+ with fly ash geopolymers was investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopic (XPS) techniques. The chromium sludge, as Cr(OH)3, was prepared with chemical precipitation method. The amounts of aluminum and silicon leached before and after the chromium sludge addition were measured using ICP-AES. The results suggested that the amounts of silicon and aluminum leached were reduced for the fly ash geopolymers after chromium sludge was incorporated. The decrease of silicon leaching was more pronounced than aluminum. FTIR results showed that the intensity of the main peak shifted into lower and the wave number of Si--O--Si and Al--O--Si became higher. The XPS results indicated that the O(1s) bind energy decreased, Si(2p) and Cr(2p) bind energy increased, while Al(2p) bind energy remained unchanged due to Cr3+ addition. It was also confirmed that the chromium is easily incorporated into the fly ash geopolymers paste, and polymerized with silicate units. The immobilization of Cr3+ using fly ash geopolymers is attributed not only to physical encapsulation, but also to chemical reaction.

  12. Investigation of damaged interior walls using synchrotron-based XPS and XANES.

    PubMed

    Poo-arporn, Yingyot; Thachepan, Surachai; Palangsuntikul, Rungtiva

    2015-01-01

    Evidence of internal sulfate attack in field exposure was demonstrated by the damaged interior wall of a three-year-old house situated in Nakhon Ratchasima Province, Thailand. Partial distension of the mortar was clearly observed together with an expansion of a black substance. Removal of the black substance revealed a dense black layer. This layer was only found in the vicinity of the damaged area, suggesting that this black material is possibly involved in the wall cracking. By employing synchrotron-based X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) techniques, the unknown sample was chemically identified. The S 2p and O 1s XPS results mutually indicated the existence of sulfate species in the materials collected from the damaged area. The XANES results indicated the presence of ferrous (II) sulfate, confirming sulfate-induced expansion and cracking. The sulfate attack in the present case appeared to physically affect the structure whereas the chemical integrity at the molecular level of the calcium silicate hydrate phase was retained since there was a lack of spectroscopic evidence for calcium sulfate. It was speculated that internal sulfate probably originated from the contaminated aggregates used during the construction. The current findings would be beneficial for understanding the sulfate-attack mechanism as well as for future prevention against sulfate attack during construction.

  13. XPS characterization scheme for phase-pure epitaxial NbO2

    NASA Astrophysics Data System (ADS)

    Hadamek, Tobias; Posadas, Agham; Demkov, Alex

    NbO2 shows a semiconductor-to-metal transition with an associated structural transition of Peierls type. NbO2 and Nb2O5 or mixtures thereof have also shown electrically induced insulator-to-metal transitions. To shed light on the nature of the electrically induced insulator-to-metal transition it is important to grow high phase purity NbO2 and Nb2O5 and compare electrical measurements with mixed niobium oxides and with different electrode materials. Processing NbO2 and avoiding surface oxidation requires ultra-high vacuum (UHV) conditions. Niobium oxide thin films where grown in UHV by molecular beam epitaxy on 111-oriented STO substrates and analyzed by X-ray photoelectron spectroscopy (XPS). It was shown that the NbO2 3d core level spectrum exhibits an asymmetric spin-orbit peak pair with more spectral weight on the high binding energy side. Based on the shape of the Nb 3d core levels, peak positions relative to the oxygen O 1s peak, and the valence band shape and height ratio of the niobium 4dxy split-off band to the oxygen 2p band, an identification scheme for NbO2 by XPS was devised. Complementary the NbO2 phase was confirmed by reflection high-energy electron and x-ray diffraction analysis.

  14. FTIR and XPS studies of protein adsorption onto functionalized bioactive glass.

    PubMed

    Gruian, C; Vanea, E; Simon, S; Simon, V

    2012-07-01

    Adsorption and structural changes that occur upon interaction between methemoglobin (MetHb) and 5-methyl-aminomethyl-uridine forming enzyme (MnmE) with the surface of a bioactive glass (BG) were investigated by Fourier Transform Infrared (FTIR) spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The effect of glutaraldehyde (GA) as a coupling agent for protein adsorption on BG was also investigated. The comparative analysis of FTIR spectra recorded from lyophilized proteins and from bioactive glass surface after protein adsorption was considered in order to obtain information about the changes in the secondary structure of the proteins. XPS data were used to determine the surface coverage. The unfolding of adsorbed proteins due to interactions between the internal hydrophobic protein domains and the hydrophobic BG surface was evidenced. After adsorption, the amount of α-helix decreases and less ordered structures (turns, random coils and aggregates) are preponderant. These changes are less pronounced on the BG functionalized with GA, suggesting that the treatment with GA preserves significantly larger amounts of α-helices in the structure of both proteins after adsorption.

  15. Rondorfite-type structure — XPS and UV–vis study

    SciTech Connect

    Dulski, M.; Bilewska, K.; Wojtyniak, M.; Szade, J.; Kusz, J.; Nowak, A.; Wrzalik, R.; and others

    2015-10-15

    Highlights: • Structural and spectroscopic characterization of chlorosilicate mineral, rondorfite. • Characterization of main photoemission lines and valence band spectra. • The study of color origin’s using UV–vis spectroscopy. • Analysis of structural changes in context of origin of natural fluorescence. • Discussion of a new application possibilities of analyzed mineral - Abstract: This paper focuses on X-ray diffraction, X-ray photoelectron and UV–vis spectroscopy of two different (green, orange) rondorfite samples. The differences in the sample color originate from various O/Cl ratios. The orange color was found to be related either to the isomorphic substitution of Fe{sup 3+}/Al{sup 3+} for Mg{sup 2+}, the presence of atypical [MgO{sub 4}] tetrahedrons in crystal structure or electronegativity of the sample. The tetrahedron is known to be very prone to accumulation of impurities and substitute atoms. Moreover, the XPS data showed tetrahedrally coordinated Mg{sup 2+} and isomorphic substitution of Al{sup 3+}/Fe{sup 3+} for Mg{sup 2+}, which influences local disordering and the point defects density and distribution. Non-equilibrium chlorine positions inside the crystal cages as well as Ca-Cl bonds have also been found. The XPS measurements as a function of temperature indicate occurrence of a structural transformation at about 770 K which is accompanied by a rotation of silicate tetrahedra within magnesiosilicate pentamer and luminescence disappearance.

  16. XPS and NEXAFS studies of VUV/O₃-treated aromatic polyurea and its application to microchip electrophoresis.

    PubMed

    Shinohara, H; Nakahara, A; Kitagawa, F; Takahashi, Y; Otsuka, K; Shoji, S; Ohara, O; Mizuno, J

    2011-12-01

    In this study, the authors performed X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) studies of vacuum ultraviolet (VUV)/O₃-treated aromatic polyurea films to investigate their treatment effects. XPS and NEXAFS spectra indicate that the benzene ring was cleaved after treatment and that carboxyl, hydroxyl, ketone and aldehyde groups were formed at the cleaved sites. The VUV/O₃-treated polyurea film was applied to a polymethylmethacrylate (PMMA) microchip for microchip electrophoresis (MCE) of bovine serum albumin (BSA). Fast electro-osmotic mobility of 4.6×10(-4) cm²/V/s as well as reduction of the BSA adhesion was achieved. This functional surface is useful for high-speed MCE analysis.

  17. Quantifying the Impact of Nanoparticle Coatings and Non-uniformities on XPS Analysis: Gold/silver Core-shell Nanoparticles

    SciTech Connect

    Wang, Yung-Chen Andrew; Engelhard, Mark H.; Baer, Donald R.; Castner, David G.

    2016-03-07

    Abstract or short description: Spectral modeling of photoelectrons can serve as a valuable tool when combined with X-ray photoelectron spectroscopy (XPS) analysis. Herein, a new version of the NIST Simulation of Electron Spectra for Surface Analysis (SESSA 2.0) software, capable of directly simulating spherical multilayer NPs, was applied to model citrate stabilized Au/Ag-core/shell nanoparticles (NPs). The NPs were characterized using XPS and scanning transmission electron microscopy (STEM) to determine the composition and morphology of the NPs. The Au/Ag-core/shell NPs were observed to be polydispersed in size, non-circular, and contain off-centered Au-cores. Using the average NP dimensions determined from STEM analysis, SESSA spectral modeling indicated that washed Au/Ag-core shell NPs were stabilized with a 0.8 nm l

  18. Surface and bulk investigation of ZSM5 and Al-MCM-41 usingsynchrotron XPS, XANES, and hexane cracking

    SciTech Connect

    Jalil, P.A.; Kariapper, M.S.; Faiz, Z.; Tabet, N.; Hamdan, N.M.; Diaz, J.; Hussain, Z.

    2005-05-12

    We present a comparative study of ZSM5 and Al-MCM-41 catalysts using spectroscopic and chemical techniques. The analysis of conventional and synchrotron XPS spectra of these catalysts reveals the presence of a topmost surface-related Si peak in addition to the bulk peak. XANES results suggest structural modification upon heating Al-MCM-41 at 500 C. Depth-resolved XPS data show Al depletion from the surface of Al-MCM-41 in contrast to surface enrichment of Al in ZSM5. These surface modifications could be one of the reasons for the weak acidity of Al-MCM-41 in chemical reactions such as hexane cracking at different temperatures.

  19. Surface and bulk investigation of ZSM5 and Al-MCM-41 usingsynchrotron XPS, XANES, and hexane cracking

    SciTech Connect

    Jalil, P.A.; Kariapper, M.S.; Faiz, Z.; Tabet, N.; Hamdan, N.M.; Diaz, J.; Hussain, Z.

    2005-05-12

    We present a comparative study of ZSM5 and Al-MCM-41 catalysts using spectroscopic and chemical techniques. The analysis of conventional and synchrotron XPS spectra of these catalysts reveals the presence of a topmost surface-related Si peak in addition to the bulkpeak. XANES results suggest structural modification upon heating Al-MCM-41 at 500 C. Depth-resolved XPS data show Al depletion from the surface of Al-MCM-41 in contrast to surface enrichment of Al in ZSM5. These surface modifications could be one of the reasons for the weak acidity of Al-MCM-41 in chemical reactions such as hexane cracking at different temperatures.

  20. N1s and O1s double ionization of the NO and N{sub 2}O molecules

    SciTech Connect

    Hedin, L.; Zhaunerchyk, V.; Karlsson, L.; Pernestål, K.; Feifel, R.; Tashiro, M.; Ehara, M.; Linusson, P.; Eland, J. H. D.; Ueda, K.

    2014-01-28

    Single-site N1s and O1s double core ionisation of the NO and N{sub 2}O molecules has been studied using a magnetic bottle many-electron coincidence time-of-flight spectrometer at photon energies of 1100 eV and 1300 eV. The double core hole energies obtained for NO are 904.8 eV (N1s{sup −2}) and 1179.4 eV (O1s{sup −2}). The corresponding energies obtained for N{sub 2}O are 896.9 eV (terminal N1s{sup −2}), 906.5 eV (central N1s{sup −2}), and 1174.1 eV (O1s{sup −2}). The ratio between the double and single ionisation energies are in all cases close or equal to 2.20. Large chemical shifts are observed in some cases which suggest that reorganisation of the electrons upon the double ionization is significant. Δ-self-consistent field and complete active space self-consistent field (CASSCF) calculations were performed for both molecules and they are in good agreement with these results. Auger spectra of N{sub 2}O, associated with the decay of the terminal and central N1s{sup −2} as well as with the O1s{sup −2} dicationic states, were extracted showing the two electrons emitted as a result of filling the double core holes. The spectra, which are interpreted using CASSCF and complete active space configuration interaction calculations, show atomic-like character. The cross section ratio between double and single core hole creation was estimated as 1.6 × 10{sup −3} for nitrogen at 1100 eV and as 1.3 × 10{sup −3} for oxygen at 1300 eV.

  1. ToF-SIMS and XPS study of ancient papers

    NASA Astrophysics Data System (ADS)

    Benetti, Francesca; Marchettini, Nadia; Atrei, Andrea

    2011-01-01

    The surface composition of 18th century papers was investigated by means of ToF-SIMS and XPS. The aim of the present study was to explore the possibility of using these surface sensitive methods to obtain information which can help to determine the manufacturing process, provenance and state of conservation of ancient papers. The ToF-SIMS results indicate that the analyzed papers were sized by gelatin and that alum was added as hardening agent. The paper sheets produced in near geographical areas but in different paper mills exhibit a similar surface composition and morphology of the fibers as shown by the ToF-SIMS measurements. The ToF-SIMS and the XPS results indicate that a significant fraction of the cellulose fibers is not covered by the gelatin layer. This was observed for the ancient papers and for a modern handmade paper manufactured according to the old recipes.

  2. XPS investigations of tribofilms formed on CrN coatings

    NASA Astrophysics Data System (ADS)

    Mandrino, Djordje; Podgornik, Bojan

    2017-02-01

    Action of lubrication additives in the case of uncoated steel surfaces, including the type and mechanism of tribofilm formation is well known and understood. However, contact type of tribofilms which might form under the tribological contact between CrN coated surfaces, remains more or less unexplored. The aim of this investigation was to study the type of tribofilms formed on the CrN coated steel samples subjected to lubricated reciprocating sliding contact under different contact conditions Contact surface and tribofilms formed were studied by X-ray Photoelectron Spectroscopy (XPS). Sample surfaces were first imaged by Scanning Electron Microscopy (SEM) to determine areas of tribofilm formation as well as areas not affected by tribological contact. In these areas survey and high resolution (HR) XPS measurements were performed to obtain information about surface chemistry and oxidation states of the constituent elements. It was found that differences between different samples, observed by the XPS measurements, may reflect differences in chemistry of tribofilms formed under different contact conditions.

  3. pH dependence of uranyl retention in a quartz/solution system: an XPS study.

    PubMed

    Froideval, A; Del Nero, M; Barillon, R; Hommet, J; Mignot, G

    2003-10-15

    We have investigated the pH dependence of U(VI) retention in quartz/10(-4) M uranyl solution systems, under conditions favoring formation of polynuclear aqueous species and of colloids of amorphous schoepite as U(VI) solubility-limiting phases. X-ray photoelectron spectroscopy was used to gain insights into the coordination environments of sorbed/precipitated uranyl ions in the centrifuged quartz samples. The U4f XPS spectra made it possible to identify unambiguously the presence of two uranyl components. A high binding energy component, whose relative proportion increases with pH, exhibits the U4f lines characteristic of a reference synthetic metaschoepite. Such a high binding energy component is interpreted as a component having a U(VI) oxide hydrate character, either as polynuclear surface oligomers and/or as amorphous schoepite-like (surface) precipitates. Its pH dependence suggests that a binding of polynuclear species at quartz surfaces and/or a formation of amorphous schoepite-like (surface) precipitates is favored when the proportion of aqueous polynuclear species increases. A second surface component exhibits binding energies for the U4f core levels at values significantly lower (DeltaE(b)=1.2 eV) than for metaschoepite, evidencing uranyl ions in a distinct coordination environment. Such a low binding energy component may be attributed to monomeric uranyl surface complexes on the basis of published EXAFS data. Such a hypothesis is supported by a major contribution of the low binding energy component to the U4f XPS spectra of reference samples for uranyl sorbed on quartz from very acidic 10(-3) M uranyl solutions where UO(2)(2+) ions predominate.

  4. Core-level spectra and binding energies of transition metal nitrides by non-destructive x-ray photoelectron spectroscopy through capping layers

    NASA Astrophysics Data System (ADS)

    Greczynski, G.; Primetzhofer, D.; Lu, J.; Hultman, L.

    2017-02-01

    We present the first measurements of x-ray photoelectron spectroscopy (XPS) core level binding energies (BE:s) for the widely-applicable group IVb-VIb polycrystalline transition metal nitrides (TMN's) TiN, VN, CrN, ZrN, NbN, MoN, HfN, TaN, and WN as well as AlN and SiN, which are common components in the TMN-based alloy systems. Nitride thin film samples were grown at 400 °C by reactive dc magnetron sputtering from elemental targets in Ar/N2 atmosphere. For XPS measurements, layers are either (i) Ar+ ion-etched to remove surface oxides resulting from the air exposure during sample transfer from the growth chamber into the XPS system, or (ii) in situ capped with a few nm thick Cr or W overlayers in the deposition system prior to air-exposure and loading into the XPS instrument. Film elemental composition and phase content is thoroughly characterized with time-of-flight elastic recoil detection analysis (ToF-E ERDA), Rutherford backscattering spectrometry (RBS), and x-ray diffraction. High energy resolution core level XPS spectra acquired with monochromatic Al Kα radiation on the ISO-calibrated instrument reveal that even mild etching conditions result in the formation of a nitrogen-deficient surface layer that substantially affects the extracted binding energy values. These spectra-modifying effects of Ar+ ion bombardment increase with increasing the metal atom mass due to an increasing nitrogen-to-metal sputter yield ratio. The superior quality of the XPS spectra obtained in a non-destructive way from capped TMN films is evident from that numerous metal peaks, including Ti 2p, V 2p, Zr 3d, and Hf 4f, exhibit pronounced satellite features, in agreement with previously published spectra from layers grown and analyzed in situ. In addition, the N/metal concentration ratios are found to be 25-90% higher than those obtained from the corresponding ion-etched surfaces, and in most cases agree very well with the RBS and ToF-E ERDA values. The N 1 s BE:s extracted from

  5. XPS study of nitrogen dioxide adsorption on metal oxide particle surfaces under different environmental conditions.

    PubMed

    Baltrusaitis, Jonas; Jayaweera, Pradeep M; Grassian, Vicki H

    2009-10-01

    The adsorption of nitrogen dioxide on gamma aluminium oxide (gamma-Al(2)O(3)) and alpha iron oxide (alpha-Fe(2)O(3)) particle surfaces under various conditions of relative humidity, presence of molecular oxygen and UV light has been investigated. X-Ray photoelectron spectroscopy (XPS) is used to monitor the different surface species that form under these environmental conditions. Adsorption of NO(2) on aluminum oxide particle surfaces results primarily in the formation of surface nitrate, NO(3)(-) with an oxidation state of +5, as indicated by a peak with binding energy of 407.3 eV in the N1s region. An additional minority species, sensitive to the presence of relative humidity and molecular oxygen, is also observed in the N1s region with lower binding energy of 405.9 eV. This peak is assigned to a surface species in the +4 oxidation state. When irradiated with UV light, other species form on the surface. These surface-bound photochemical products all have lower binding energy, between 400 and 402 eV, indicating reduced nitrogen species in the range of N oxidations states spanning +1 to -1. Co-adsorbed water decreases the amount of these reduced surface-bound products while the presence of molecular oxygen completely suppresses the formation of all reduced nitrogen species on aluminum oxide particle surfaces. For NO(2) on iron oxide particle surfaces, photoreduction is enhanced relative to gamma-Al(2)O(3) and surface bound photoreduced species are observed under all environmental conditions. Complementing the experimental data, N1s core electron binding energies (CEBEs) were calculated using DFT for a number of nitrogen-containing species in the gas phase and adsorbed on an Al(8)O(12) cluster. A range of CEBEs is calculated for various nitrogen species in different adsorption modes and oxidation states. These calculated values are discussed in light of the peaks observed in the XPS N1s region and the possible species that form following NO(2) adsorption and

  6. Simultaneous Use Of Zr And Mg Anodes In XPS

    NASA Technical Reports Server (NTRS)

    Allgeyer, D. F.; Pratz, E. H.

    1996-01-01

    Improved x-ray source for x-ray photoelectron spectroscopy (XPS) contains both zirconium anode with beryllium window and magnesium anode with aluminum window. Previously unresolvable peaks of electron-energy spectrum become resolvable. Developed specifically for use in analyzing distributions of chemical constituents in surface layers of specimens of 2219 aluminum alloy and in determining the depths of surface oxide layers and relative proportions of aluminum and oxide in layers. Also used to study chemical constituents of surface layers in other material systems - for example, thin oxide films on silicon-based semiconductor devices, oxide films on alloys, and surface layers affecting adhesion of paints or bonding materials.

  7. Effects of the low Earth orbit space environment on the surface chemistry of Kapton polyimide film: An XPS study

    NASA Technical Reports Server (NTRS)

    Lee, Myung; Rooney, William; Whiteside, James

    1992-01-01

    Kapton H (DuPont Trademark) polyimide specimens exposed to the low earth (LEO) space environment suffered significant weathering with surface erosions of approximately 8.0 microns. Despite these effects, no significant changes in bulk chemistry were observed. X-ray photoelectron spectroscopy (XPS) was used to determine local changes induced from approximately 25 percent in 1980 vintage ground control specimens to nearly 53 percent in space exposed specimens. The greatest increase was observed for the divalent oxygen moieties, although a slight increase in carbonyl oxygen was also measured. Furthermore, the chemical shifts of all XPS peaks of space-exposed Kapton are shifted to higher energy. This is consistent with a higher oxidation state of the space exposed surface. Finally, space exposed specimens had distinct silicon peaks (2p 100 eV and 2s 149 eV) in their XPS spectra in agreement with widespread reports of silicon contamination throughout the LDEF satellite. These results are discussed in terms of surface reactivity of the polyimide exposed to the LEO environment and the chemical nature of contaminants deposited on flight surfaces due to satellite outgassing.

  8. Use of XPS to clarify the Hall coefficient sign variation in thin niobium layers buried in silicon

    NASA Astrophysics Data System (ADS)

    Demchenko, Iraida N.; Lisowski, Wojciech; Syryanyy, Yevgen; Melikhov, Yevgen; Zaytseva, Iryna; Konstantynov, Pavlo; Chernyshova, Maryna; Cieplak, Marta Z.

    2017-03-01

    Si/Nb/Si trilayers formed with 9.5 and 1.3 nm thick niobium layer buried in amorphous silicon were prepared by magnetron sputtering and studied using XPS depth-profile techniques in order to investigate the change of Hall coefficient sign with thickness. The analysis of high-resolution (HR) XPS spectra revealed that the thicker layer sample has sharp top interface and metallic phase of niobium, thus holes dominate the transport. In contrast, the analysis indicates that the thinner layer sample has a Nb-rich mixed alloy formation at the top interface. The authors suggest that the main effect leading to a change of sign of the Hall coefficient for the thinner layer sample (which is negative contrary to the positive sign for the thicker layer sample) may be related to strong boundary scattering enhanced by the presence of silicon ions in the layer close to the interface/s. The depth-profile reconstruction was performed by SESSA software tool confirming that it can be reliably used for quantitative analysis/interpretation of experimental XPS data.

  9. Inequality spectra

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo

    2017-03-01

    Inequality indices are widely applied in economics and in the social sciences as quantitative measures of the socioeconomic inequality of human societies. The application of inequality indices extends to size-distributions at large, where these indices can be used as general gauges of statistical heterogeneity. Moreover, as inequality indices are plentiful, arrays of such indices facilitate high-detail quantification of statistical heterogeneity. In this paper we elevate from arrays of inequality indices to inequality spectra: continuums of inequality indices that are parameterized by a single control parameter. We present a general methodology of constructing Lorenz-based inequality spectra, apply the general methodology to establish four sets of inequality spectra, investigate the properties of these sets, and show how these sets generalize known inequality gauges such as: the Gini index, the extended Gini index, the Rényi index, and hill curves.

  10. Data warehousing features in Informix OnLine XPS

    SciTech Connect

    Sundaresan, P.

    1996-12-31

    The Data Warehousing application domain is an important area of focus for Informix`s OnLine XPS massively parallel server. Fast query processing is a central requirement in this domain. Use of indexes has traditionally been an important query processing technique, helping to reduce response times and increase throughput. The data warehousing environment, characterized by its load-query-refresh mode of operation, offers even greater scope for use of indexes. This talk will describe three new indexing related features in OnLine XPS which together provide significant performance benefits in a wide variety of situations. Bitmap indexes, along with multi-index scans, provide orders-of-magnitude improvement for queries typified by the Set Query Benchmark. Pushdown Semi-joins combine the benefits of multi-index scans with the scalability of hash joins to efficiently process star-joins. Finally, Generalized-key indexes expand the notion of what can be an index key and provide the ability to store various pre-computed results in an index. Optimizer extensions allow these features to be used in a mix-n-match fashion, thus maximizing the benefits of these features while minimizing the need for user level directives.

  11. Potential for carbon adsorption on concrete: surface XPS analyses.

    PubMed

    Haselbach, Liv M; Ma, Shuguo

    2008-07-15

    The concrete industry is a contributor to the global carbon cycle particularly with respect to the contribution of carbon dioxide in the manufacturing of cement (calcination). The reverse reaction of carbonation is known to occur in concrete, but is usually limited to exterior surfaces exposed to carbon dioxide and humidity in the air. As alternate concrete uses expand which have more surface area, such as crushed concrete for recycling, it is important to understand surface adsorption of carbon dioxide and the positive impacts it might have on the carbon cycle. X-ray photoelectron spectroscopy (XPS) is used in this study to evaluate carbon species on hydrated cement mortar surfaces. Initial estimates for carbon absorption in concrete using othertechniques predictthe potential for carbonate species to be a fraction of the calcination stoichiometric equivalent The XPS results indicate that there is a rapid and substantial uptake of carbon dioxide on the surfaces of these mortars, sometimes exceeding the calcination stoichiometric equivalents, indicative of carbon dioxide surface complexation species. On pure calcite, the excess is on the order of 30%. This accelerated carbon dioxide surface adsorption phenomenon may be importantfor determining novel and effective carbon sequestration processes using recycled concrete.

  12. Quantitative XPS analysis of silica-supported Cu Co oxides

    NASA Astrophysics Data System (ADS)

    Cesar, Deborah V.; Peréz, Carlos A.; Schmal, Martin; Salim, Vera Maria M.

    2000-04-01

    Copper-cobalt oxides with Cu/Co=5:5, 15:15 and 35:35 bulk ratio have been prepared by deposition-precipitation method at constant pH from copper and cobalt nitrate solutions. Different oxides were obtained by decomposition of the precursors at 673 K for 7 h in air and analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). XRD data showed the formation of different oxide phases; for the bulk atomic ratio of 15Cu:15Co, a phase containing Cu and Co with spinel-like structure was observed, while the other bimetallic oxides presented CuO and Co 3O 4 as distinct phases. The XPS qualitative analysis has shown that all samples exhibited Cu 2+ and Co 3+ species at the surface. The Cu-Co spinel presented a displacement in Cu 2p binding energy value. A mathematical model was proposed from relative intensity ratios, which allowed the determination of the oxide particle thickness and the fraction of coverage at the support. This model described accurately the system and showed that cobalt improved the copper dispersion.

  13. Copper Bronze Powder Surface Studied by XPS and HR SEM

    NASA Astrophysics Data System (ADS)

    Shvab, R.; Hryha, E.; Tahir, A. M.; Nyborg, L.

    2016-10-01

    The state of the powder surface represents one of the main interests in the whole cycle of components' production using powder metallurgy (PM) route. Large specific surface area of the powder in combination with often alloying with oxygen sensitive elements results in oxidation of the powder surface in most of the cases. The information about surface chemistry of the powder is of vital importance for further consolidation and sintering steps. Surface sensitive analytical techniques - X-ray photoelectron spectroscopy (XPS) and high-resolution scanning electron microscopy combined with energy dispersive X-ray analysis (HR SEM+EDX) were used for surface chemical analysis of the 60Cu-40Sn bronze powder. Determination of the compositional profiles and estimation of the surface oxide layer thickness was done by altering of ion etching and XPS analysis. The results showed tin oxide enrichment and presence of copper hydroxide on the surface of the powder particles. The impurities of P, Zn and Ca were also detected on the top surface of the powder in trace amounts.

  14. [Analysis of XPS in the removal of Se(IV) from groundwater with pyrite].

    PubMed

    Liu, Hong-fang; Qian, Tian-wei; Zhang, Min-gang

    2015-02-01

    Selenium (Se) is an elementary trace nutrient element for human but there is a very narrow range between deficit and toxic levels. Furthermore, excessive intake of Selenium is harmful for human. The product species of selenite which was removal by pyrite particles was studied in the present research In the experiments, the pyrite particles were prepared by the wet ball mill method, and surface analyses of pyrite before and after contact with Se(IV) were conducted using X-ray photoelectron spectroscopy (XPS). Besides, the prepared pyrite samples were also characterized using both X-ray diffraction (XRD) and scanning electron microscope (SEM). X-ray diffraction analysis indicated that the purity of the prepared pyrite particles was above 97%, and the characteristic diffraction peaks of the particles well matched with that of FeS2 crystalline. Scanning electron microscope determination showed the shape of the particles was approximate ball and the size was range from 80 to 180 nm. And thus the pyrite particles prepared by the wet ball mill method had less particle size, larger specific surface area and higher reactive ability. The batch experiments exhibited the pyrite particles were able to remove 95% of Se(IV) (20 mg x L(-1)) from water within 12 hours. And the kinetic tests indicated reaction process between pyrite and Se(IV) fits a pseudo-first order kinetic model, which gives a pseudo-first order rate constant(kobs) of 0.26 h(-1). XPS analyses were using the XPSPEAK program which has a Gaussian Lorentzian function. The results clearly displays that Se(IV) prefer to react with the surface-bound S2(2-) rather than reacted with the surface-bound Fe2+ of pyrite particles. From XPS graph, it can be seen that the binding energy of sulfur element and iron element composed of pyrite shifted to the left a little, which means expensive state of sulfur element and iron element appeared on the pyrite surface. Analysis of the oxidation state of Se on the surface of pyrite

  15. XPS study of interface formation of CVD SiO2 on InSb. [X-ray Photoemission Spectroscopy

    NASA Technical Reports Server (NTRS)

    Vasquez, R. P.; Grunthaner, F. J.

    1981-01-01

    The interfacial chemistry of CVD SiO2 films deposited on thin native oxides grown on InSb substrates is examined using X-ray photoemission spectroscopy (XPS) and a relatively benign chemical etching technique for depth profiling. An intensity analysis of XPS spectra is used to derive the compositional structure of the interfaces obtained in the SiO2/native oxide/InSb system. Peak positions in these spectra are used to follow the change in substrate surface potential during the etch sequence, and to establish the chemical nature of the species formed during deposition and subsequent processing. Reaction of the substrate with oxygen resulted in an In-rich native oxide and 1-2 monolayers of excess elemental Sb at the native-oxide/substrate interface, incompletely oxidized silane reduced the native oxide, leaving less than 1 monolayer of elemental In at the SiO2/native oxide interface. Etch removal of this thin In-rich layer leads to a change in the substrate surface potential of 0.06 eV, corresponding to a net increase in positive charge. The results are consistent with simple thermodynamic considerations; they are also compared to previously reported studies of deposited dielectrics on III-V compound semiconductors.

  16. Surface Propensity of Atmospherically Relevant Amino Acids Studied by XPS.

    PubMed

    Mocellin, Alexandra; Gomes, Anderson Herbert de Abreu; Araújo, Oscar Cardoso; de Brito, Arnaldo Naves; Bjorneholm, Olle

    2017-03-30

    Amino acids constitute an important fraction of the water-soluble organic nitrogen (WSON) compounds in aerosols and are involved in many processes in the atmosphere. In this work, we applied XPS to study aqueous solutions of four amino acids: glycine, alanine, valine and methionine, in their zwitterionic forms. We found that amino acids with hydrophilic side chains and smaller size, GLY and ALA, tend to stay in the bulk of the liquid, while the hydrophobic and bigger amino acids, VAL and MET, are found to concentrate more on the surface. We found experimental evidences that the amino acids have preferential orientation relative to the surface, with the hydrophobic side chain being closer to the surface than the hydrophilic carboxylate group. The observed amino acid surface propensity has implications in atmospheric science as the surface interaction play a central role in cloud droplet formation, and they should be considered in climate models.

  17. Screening-Constant-by-Unit-Nuclear-Charge method investigations of high lying ({sup 1}D{sub 2},{sup 1}S{sub 0}) ns, nd Rydberg series in the photoionization spectra of the halogen-like ion Kr{sup +}

    SciTech Connect

    Sakho, I.

    2014-01-15

    Energy positions and quantum defects of the 4s{sup 2}4p{sup 4} ({sup 1}D{sub 2},{sup 1}S{sub 0}) ns, nd Rydberg series originating from the 4s{sup 2}4p{sup 52}P{sub 3/2}{sup ∘} ground state and from the 4s{sup 2}4p{sup 52}P{sub 1/2}{sup ∘} metastable state of Kr{sup +} are reported. Calculations are performed using the Screening Constant by Unit Nuclear Charge (SCUNC) method. The results obtained are in suitable agreement with recent experimental data from the combined ASTRID merged-beam set up and Fourier Transform Ion Cyclotron Resonance device (Bizau et al., 2011), ALS measurements (Hinojosa et al., 2012), and multi-channel R-matrix eigenphase derivative calculations (McLaughlin and Balance, 2012). In addition, analysis of the 4s{sup 2}4p{sup 4}({sup 1}D{sub 2})nd and the 4s{sup 2}4p{sup 4}({sup 1}S{sub 0})nd resonances is given via the SCUNC procedure. The excellent results obtained from our work point out that the SCUNC formalism may be used to confirm the results of the analysis from the standard quantum-defect expansion formulas. Eventual errors occurring in the analysis can then be automatically detected and corrected via the SCUNC procedure.

  18. Os layers spontaneously deposited on the Pt(111) electrode : XPS, STM and GIF-XAS study.

    SciTech Connect

    Rhee, C. K.; Wakisaka, M.; Tolmachev, Y.; Johnston, C.; Haasch, R.; Attenkofer, K.; Lu, G. Q.; You, H.; Wieckowski, A.; Univ. of Illinois Champaigh-Urbana

    2003-01-01

    expected from voltammetry. Also, the observed intensity of the white line of Os in the 100-400 mV region is larger than the value reported for metallic bulk Os. This discrepancy may result from the difference in the electronic properties of the metallic Os layers on Pt(111) and the metallic bulk Os: in the potential region between 100 and 400 mV, the 5d electrons in Os and Pt form a mixed electronic band, and the density of electronic states near the Fermi level, the main factor determining the white line intensity, may not be the same as in metallic bulk. The presented results on osmium adlayers are much more comprehensive than those available in our previous work due to the combined STM, GIF-XAS and XPS investigations. A nearly perfect convergence of the in situ and ex situ data is one of the main research outcomes of this project. Finally, platinum XPS spectra taken in the context of Os electrooxidation from the electrode surface are also presented and conclusions are made, that up to 900 mV platinum remain metallic, irrespective of a significant osmium oxidation on its surface.

  19. The surface chemistry of nanocrystalline MgO catalysts for FAME production: An in situ XPS study of H2O, CH3OH and CH3OAc adsorption

    NASA Astrophysics Data System (ADS)

    Montero, J. M.; Isaacs, M. A.; Lee, A. F.; Lynam, J. M.; Wilson, K.

    2016-04-01

    An in situ XPS study of water, methanol and methyl acetate adsorption over as-synthesised and calcined MgO nanocatalysts is reported with a view to gaining insight into the surface adsorption of key components relevant to fatty acid methyl esters (biodiesel) production during the transesterification of triglycerides with methanol. High temperature calcined NanoMgO-700 adsorbed all three species more readily than the parent material due to the higher density of electron-rich (111) and (110) facets exposed over the larger crystallites. Water and methanol chemisorb over the NanoMgO-700 through the conversion of surface O2 - sites to OH- and coincident creation of Mg-OH or Mg-OCH3 moieties respectively. A model is proposed in which the dissociative chemisorption of methanol occurs preferentially over defect and edge sites of NanoMgO-700, with higher methanol coverages resulting in physisorption over weakly basic (100) facets. Methyl acetate undergoes more complex surface chemistry over NanoMgO-700, with C-H dissociation and ester cleavage forming surface hydroxyl and acetate species even at extremely low coverages, indicative of preferential adsorption at defects. Comparison of C 1s spectra with spent catalysts from tributyrin transesterification suggest that ester hydrolysis plays a key factor in the deactivation of MgO catalysts for biodiesel production.

  20. Samarium and europium beta”-alumina derivatives characterized by XPS

    DOE PAGES

    Myhre, Kristian; Meyer, Harry; Du, Miting

    2017-01-04

    Characterization of sodium, samarium and europium beta -alumina derivatives has been carried out using X-ray photoelectron spectroscopy. Beta -alumina has been widely studied as a material capable of incorporating many different cations into its lattice structure, such as sodium and many of the lanthanide elements. The X-ray photoelectron spectra of samarium and europium in the beta -alumina structure are reported here. Additionally, the spectra of the precursor sodium beta -alumina as well as the europium and samarium trichloride starting materials are presented.

  1. XPS and EELS characterization of Mn2SiO4, MnSiO3 and MnAl2O4

    NASA Astrophysics Data System (ADS)

    Grosvenor, A. P.; Bellhouse, E. M.; Korinek, A.; Bugnet, M.; McDermid, J. R.

    2016-08-01

    X-ray Photoelectron Spectroscopy (XPS) and Electron Energy Loss Spectroscopy (EELS) are strong candidate techniques for characterizing steel surfaces and substrate-coating interfaces when investigating the selective oxidation and reactive wetting of advanced high strength steels (AHSS) during the continuous galvanizing process. However, unambiguous identification of ternary oxides such as Mn2SiO4, MnSiO3, and MnAl2O4 by XPS or EELS, which can play a significant role in substrate reactive wetting, is difficult due to the lack of fully characterized standards in the literature. To resolve this issue, samples of Mn2SiO4, MnSiO3 and MnAl2O4 were synthesized and characterized by XPS and EELS. The unique features of the XPS and EELS spectra for the Mn2SiO4, MnSiO3 and MnAl2O4 standards were successfully derived, thereby allowing investigators to fully differentiate and identify these oxides at the surface and subsurface of Mn, Si and Al alloyed AHSS using these techniques.

  2. Chemistry Characterization of Jet Aircraft Engine Particulate by XPS: Results from APEX III

    NASA Technical Reports Server (NTRS)

    Vander Wal, Randy L.; Bryg, Victoria M.

    2014-01-01

    This paper reports XPS analysis of jet exhaust particulate from a B737, Lear, ERJ, and A300 aircraft during the APEX III NASA led field campaign. Carbon hybridization and bonding chemistry are identified by high-resolution scans about the C1s core-shell region. Significant organic content as gauged by the sp3/sp2 ratio is found across engines and platforms. Polar oxygen functional groups include carboxylic, carbonyl and phenol with combined content of 20 percent or more. By lower resolution survey scans various elements including transition metals are identified along with lighter elements such as S, N, and O in the form of oxides. Burning additives within lubricants are probable sources of Na, Ba, Ca, Zn, P and possibly Sn. Elements present and their percentages varied significantly across all engines, not revealing any trend or identifiable cause for the differences, though the origin is likely the same for the same element when observed. This finding suggests that their presence can be used as a tracer for identifying soots from aircraft engines as well as diagnostic for monitoring engine performance and wear.

  3. Chemistry characterization of jet aircraft engine particulate matter by XPS: Results from APEX III

    NASA Astrophysics Data System (ADS)

    Vander Wal, Randy L.; Bryg, Victoria M.; Huang, Chung-Hsuan

    2016-09-01

    This paper reports X-ray photoelectron spectroscopy (XPS) analysis of jet exhaust particulate matter (PM) from a B737, Lear, ERJ and A300 aircraft during the APEX III NASA led field campaign. Carbon hybridization and bonding chemistry are identified by high-resolution scans about the C1s core-shell region. Significant organic content as gauged by the sp3/sp2 ratio is found across engines and powers. Polar oxygen functional groups include carboxylic, carbonyl and phenol with combined content of 20% or more. By survey scans various elements including transition metals are identified along with lighter elements such as S, N and O in the form of oxides. Additives within lubricants are probable sources of Na, Ba, Ca, Zn, P and possibly Sn. Elements present and their percentages varied significantly across all engines, not revealing any trend or identifiable cause for the differences, though the origin is likely the same for the same element when observed. This finding suggests that their collective presence could serve as an environmental tracer for identifying PM originating from aircraft engines and serving as a diagnostic for engine performance and wear.

  4. Iridescent Art Nouveau glass - IBA and XPS for the characterisation of thin iridescent layers

    NASA Astrophysics Data System (ADS)

    Jembrih, D.; Neelmeijer, C.; Schreiner, M.; Mäder, M.; Ebel, M.; Svagera, R.; Peev, M.

    2001-07-01

    The external proton beam of the Tandem accelerator of the Research Centre in Rossendorf/Germany was used to carry out non-destructive particle-induced X-ray emission (PIXE) particle-induced gamma-ray emission (PIGE) and Rutherford backscattering (RBS) measurements simultaneously on Art Nouveau artifacts produced around 1900 by Tiffany/USA and Loetz/Austria. These studies should proof the technology of producing an iridescent layer on a glass surface. By means of the yield ratio Y(Si-K)/ Y(Si-γ) of both characteristic X-radiation (Si-K) and γ-radiation (Si-γ) of the element silicon it could be shown that a thin top layer is present on the glass surface due to the treatment of the heated artifacts (about 500°C) with an alcoholic solution of SnCl 2[1]. Combined evaluation of the PIXE and RBS spectra resulted in a thickness of 20-300 nm for this top layer. In addition, a transition region between the iridescent layer and the bulk glass was obtained by RUMP simulations. Approximately 80% of the total amount of the Sn were found to be present in this transition layer and only 10-20% in the outermost surface region. XPS studies showed that the outermost layer consists of SnO 2. The formation of other Sn compounds in the outermost near-surface region based on Sn-Si-O during the manufacturing process can be excluded.

  5. Investigation of adhesion between molybdenum and polysilazane by XPS

    NASA Astrophysics Data System (ADS)

    Amouzou, Dodji; Fourdrinier, Lionel; Sporken, Robert

    2015-07-01

    Here, we investigate the interface between polysilazane (PSZ) coatings and Mo films for understanding adhesion. Two kinds of Mo/PSZ samples are investigated (the well-adhered samples and the non-adhered samples) and the chemical environments of their interfaces are compared. For some investigations, ultra-thin Mo films (2-5 nm) are deposited on PSZ coatings to probe the interface directly by X-ray photoelectron spectroscopy (XPS) and to avoid long sputtering times in depth profiling of Mo films. It was found that the sputtered Mo films systematically adhere well to PSZ coatings. The good adhesion arises from a formation of molybdenum oxycarbonitride or molybdenum carbonitride ceramics through covalent bonding between atoms from PSZ and Mo at the interface. The nature of ceramic newly formed at the interface between PSZ and Mo films depends on deposition conditions and can lead to cohesion failure in PSZ coatings. We demonstrated that the adhesion failure observed for some samples does not occur due to the absence of bonding between atoms at interface of Mo/PSZ but may result from the chemical change.

  6. Vibrations of acrylonitrile in N 1s excited states

    NASA Astrophysics Data System (ADS)

    Ilakovac, V.; Carniato, S.; Gallet, J.-J.; Kukk, E.; Horvatić, D.; Ilakovac, A.

    2008-01-01

    The N 1s near edge x-ray absorption fine structure spectra of acrylonitrile gas are accurately reproduced by a complete ab initio multidimensional vibrational analysis. The role of π∗ -orbital localization and hybridization on vibrations accompanying core excitation is discussed. Transition to the π⊥∗(C=C-C≡N) delocalized orbital excites mostly stretching vibrations of the whole spinal column of the molecule. Promoting a core electron to the localized π∥∗(C≡N) produces C≡N stretching vibration combined with two strong bending modes of the C-C≡N end of the molecule, related to the change of carbon hybridization.

  7. XPS study of the hematite-aqueous solution interface

    SciTech Connect

    Shchukarev, Andrei; Boily, Jean F.

    2008-04-01

    The electric double layer at the surface of micrometer-sized hematite platelets dominated by the basal {001} and the edge {012} planes was investigated using the cryogenic XPS technique. Thoroughly dialysed hematite suspensions revealed the presence of surface-bound sodium (2.2 at. %) and chloride (0.4 at. %). Suspensions in 10 mM and 100 mM NaCl revealed additional uptake of sodium and chloride. The Na/Cl atomic ratio follows the pH dependence found with previous studies of goethite, manganite and gibbsite. An excess of Cl- was demonstrated at positively charged hematite surface, and Na+ at negatively charged surfaces. The surface coverage of electrolyte ions was also shown to play an important role on the presence of water at the interface. At low ionic strength the water content was about of 10 at. %, yielding a water/counter-ions atomic ratio of about 3-6, depending on pH. At 100 mM NaCl, however, the large atomic concentrations of sodium and chloride resulted in a water content of about 25 at. %, nonetheless yielding a water/counter-ion atomic ratio about 1. The presence of 100 mM CsCl, on the other hand, yielded the same amount of surface-bound water as in 10 mM NaCl due to a lower surface coverage for Cs and to its weaker affinity for water. Finally, a non-equilibrated hematite sample at pH 4 enabled a description the formation of the electric double layer upon addition of 100 mM NaCl to an electrolyte-free suspension

  8. XPS and AFM Study of GaAs Surface Treatment

    SciTech Connect

    Contreras-Guerrero, R.; Wallace, R. M.; Aguirre-Francisco, S.; Herrera-Gomez, A.; Lopez-Lopez, M.

    2008-11-13

    Obtaining smooth and atomically clean surfaces is an important step in the preparation of a surface for device manufacturing. In this work different processes are evaluated for cleaning a GaAs surface. A good surface cleaning treatment is that which provides a high level of uniformity and controllability of the surface. Different techniques are useful as cleaning treatments depending on the growth process to be used. The goal is to remove the oxygen and carbon contaminants and then form a thin oxide film to protect the surface, which is easy to remove later with thermal desorption mechanism like molecular beam epitaxy (MBE) with minimal impact to the surface. In this study, atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were used to characterize the structure of the surface, the composition, as well as detect oxygen and carbon contaminant on the GaAs surface. This study consists in two parts. The first part the surface was subjected to different chemical treatments. The chemical solutions were: (a)H{sub 2}SO{sub 4}:H{sub 2}O{sub 2}:H{sub 2}O(4:1:100), (b) HCl: H{sub 2}O(1:3), (c)NH{sub 4}OH 29%. The treatments (a) and (b) reduced the oxygen on the surface. Treatment (c) reduces carbon contamination. In the second part we made MOS devices on the surfaces treated. They were characterized by CV and IV electrical measurements. They show frequency dispersion.

  9. Evaluation Metrics for the Paragon XP/S-15

    NASA Technical Reports Server (NTRS)

    Traversat, Bernard; McNab, David; Nitzberg, Bill; Fineberg, Sam; Blaylock, Bruce T. (Technical Monitor)

    1993-01-01

    On February 17th 1993, the Numerical Aerodynamic Simulation (NAS) facility located at the NASA Ames Research Center installed a 224 node Intel Paragon XP/S-15 system. After its installation, the Paragon was found to be in a very immature state and was unable to support a NAS users' workload, composed of a wide range of development and production activities. As a first step towards addressing this problem, we implemented a set of metrics to objectively monitor the system as operating system and hardware upgrades were installed. The metrics were designed to measure four aspects of the system that we consider essential to support our workload: availability, utilization, functionality, and performance. This report presents the metrics collected from February 1993 to August 1993. Since its installation, the Paragon availability has improved from a low of 15% uptime to a high of 80%, while its utilization has remained low. Functionality and performance have improved from merely running one of the NAS Parallel Benchmarks to running all of them faster (between 1 and 2 times) than on the iPSC/860. In spite of the progress accomplished, fundamental limitations of the Paragon operating system are restricting the Paragon from supporting the NAS workload. The maximum operating system message passing (NORMA IPC) bandwidth was measured at 11 Mbytes/s, well below the peak hardware bandwidth (175 Mbytes/s), limiting overall virtual memory and Unix services (i.e. Disk and HiPPI I/O) performance. The high NX application message passing latency (184 microns), three times than on the iPSC/860, was found to significantly degrade performance of applications relying on small message sizes. The amount of memory available for an application was found to be approximately 10 Mbytes per node, indicating that the OS is taking more space than anticipated (6 Mbytes per node).

  10. Direct correlations between XPS analyses and growth film by chronopotentiometry on InP in liquid ammonia (-55 °C)

    NASA Astrophysics Data System (ADS)

    Gonçalves, A.-M.; Njel, C.; Aureau, D.; Etcheberry, A.

    2017-01-01

    This paper is based on the understanding of the formation of a reproducible polyphosphazene-like film (sbnd [(H2N)sbnd Pdbnd N]nsbnd) obtained on InP by anodic treatment in liquid ammonia. The approach is innovative as it combines indications from the coulometric charges and the related chemical information from XPS analyses. Anodic charges are accurately monitored by galvanostatic treatment between 0.05 mC cm-2 and 12.5 mC cm-2. XPS investigation of the treated surfaces demonstrates the presence of an anodic film on InP. Whatever the spent charge, the specific P2p and N1s signals agree with the growth of an ultrathin phosphazene layer. From 0.25 mC cm-2 to 12.5 mC cm-2, a quasi constant XPS response is revealed without thickening of the film. However a gradual chemical evolution of the modified surface is clearly observed for the lower anodic charges (from 0.04 mC cm-2 to 0.5 mC cm-2). In this case, the surface is entirely recovered by the film as soon as 0.25 mC cm-2 is consumed at the interface. Same atomic surface ratios are indeed revealed indicating that a constant chemical composition is consistent with a polyphosphazene film. On the basis of atomic surface ratios evolutions determined by XPS, a mechanism of the film growth is deduced. It requires a nucleation step which is followed by a phosphazene coalescence phenomenon in the two dimensions of the surface. A final phosphazene monolayer film is suggested if a sufficient anodic charge spent at the interface is considered, allowing a quantitative discussion related to electrochemical and XPS data.

  11. XPS Protocol for the Characterization of Pristine and Functionalized Single Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Sosa, E. D.; Allada, R.; Huffman, C. B.; Arepalli, S.

    2009-01-01

    Recent interest in developing new applications for carbon nanotubes (CNT) has fueled the need to use accurate macroscopic and nanoscopic techniques to characterize and understand their chemistry. X-ray photoelectron spectroscopy (XPS) has proved to be a useful analytical tool for nanoscale surface characterization of materials including carbon nanotubes. Recent nanotechnology research at NASA Johnson Space Center (NASA-JSC) helped to establish a characterization protocol for quality assessment for single wall carbon nanotubes (SWCNTs). Here, a review of some of the major factors of the XPS technique that can influence the quality of analytical data, suggestions for methods to maximize the quality of data obtained by XPS, and the development of a protocol for XPS characterization as a complementary technique for analyzing the purity and surface characteristics of SWCNTs is presented. The XPS protocol is then applied to a number of experiments including impurity analysis and the study of chemical modifications for SWCNTs.

  12. Growth of ultra-thin FeO(100) films on Ag(100): A combined XPS, LEED and CEMS study

    NASA Astrophysics Data System (ADS)

    Abreu, G. J. P.; Paniago, R.; Pfannes, H.-D.

    2014-01-01

    The production and characterization of ultra-thin iron oxide films grown on an atomically clean Ag(100) surface by molecular beam epitaxy (MBE) is presented. The goal of this work was to prepare ultra-thin FeO(100) with excellent crystallographic quality. The films were prepared with high purity 57Fe and O2 and afterwards analyzed in situ by means of Low Energy Electron Diffraction (LEED), X-Ray Photoelectron Spectroscopy (XPS) and Conversion Electron Mössbauer Spectroscopy (CEMS). During preparation the evaporation rate, the O2 partial pressure, film thickness and annealing procedures were varied. The analysis of the various samples showed that in general a mixture of FeO and Fe3O4 phases is obtained. We determined the best conditions to produce the desired oxide (FeO). Besides the paramagnetic phase, the antiferromagnetic phase of the FeO films was characterized by low temperature Mössbauer spectra.

  13. Storm Spectra

    NASA Technical Reports Server (NTRS)

    2007-01-01

    portion is defined by the day/night boundary (known as the terminator).

    These two images illustrate only a small fraction of the information contained in a single LEISA scan, highlighting just one aspect of the power of infrared spectra for atmospheric studies.

  14. XPS determination of Mn oxidation states in Mn (hydr)oxides

    NASA Astrophysics Data System (ADS)

    Ilton, Eugene S.; Post, Jeffrey E.; Heaney, Peter J.; Ling, Florence T.; Kerisit, Sebastien N.

    2016-03-01

    Hydrous manganese oxides are an important class of minerals that help regulate the geochemical redox cycle in near-surface environments and are also considered to be promising catalysts for energy applications such as the oxidation of water. A complete characterization of these minerals is required to better understand their catalytic and redox activity. In this contribution an empirical methodology using X-ray photoelectron spectroscopy (XPS) is developed to quantify the oxidation state of hydrous multivalent manganese oxides with an emphasis on birnessite, a layered structure that occurs commonly in soils but is also the oxidized endmember in biomimetic water-oxidation catalysts. The Mn2p3/2, Mn3p, and Mn3s lines of near monovalent Mn(II), Mn(III), and Mn(IV) oxides were fit with component peaks; after the best fit was obtained the relative widths, heights and binding energies of the components were fixed. Unknown multivalent samples were fit such that binding energies, intensities, and peak-widths of each oxidation state, composed of a packet of correlated component peaks, were allowed to vary. Peak-widths were constrained to maintain the difference between the standards. Both average and individual mole fraction oxidation states for all three energy levels were strongly correlated, with close agreement between Mn3s and Mn3p analyses, whereas calculations based on the Mn2p3/2 spectra gave systematically more reduced results. Limited stoichiometric analyses were consistent with Mn3p and Mn3s. Further, evidence indicates the shape of the Mn3p line was less sensitive to the bonding environment than that for Mn2p. Consequently, fitting the Mn3p and Mn3s lines yielded robust quantification of oxidation states over a range of Mn (hydr)oxide phases. In contrast, a common method for determining oxidation states that utilizes the multiplet splitting of the Mn3s line was found to be not appropriate for birnessites.

  15. XPS and STEM studies of Allende acid insoluble residues

    NASA Technical Reports Server (NTRS)

    Housley, R. M.; Clarke, D. R.

    1980-01-01

    Data on Allende acid residues obtained both before and after etching with hot HNO3 are presented. X-ray photoelectron spectra show predominantly carbonaceous material plus Fe-deficient chromite in both cases. The HNO3 oxidizes the carbonaceous material to some extent. The small chromites in these residues have a wide range of compositions somewhat paralleling those observed in larger Allende chromites and in Murchison chromites, especially in the high Al contents; however, they are deficient in divalent cations, which makes them metastable and indicates that they must have formed at relatively low temperatures. It is suggested that they formed by precipitation of Cr(3+) and Fe(3+) from olivine at low temperature or during rapid cooling.

  16. Investigation of mussel adhesive protein adsorption on polystyrene and poly(octadecyl methacrylate) using angle dependent XPS, ATR-FTIR, and AFM

    SciTech Connect

    Baty, A.M.; Suci, P.A.; Tyler, B.J.; Geesey, G.G.

    1996-02-10

    Despite many years of research effort, the molecular interactions that are responsible for microbial adhesion and fouling of surfaces remain obscure. An understanding of these interactions would contribute to the development of surfaces that resist colonization of microorganisms. The irreversible adsorption of mussel adhesive proteins (MAP) from the marine mussel Mytilus edulis has been investigated on polystyrene (PS) and poly(octadecyl methacrylate) (POMA) surfaces using angle resolved X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrometry, and atomic force microscopy (AFM). Angle resolved XPS was used to quantify the elemental composition with depth of the upper 90 {angstrom} of the surface, and AFM was used to obtain the surface topography. The adsorption pattern of MAP, revealed by AFM images, is distinctly different on the two polymer surfaces and suggests that the substratum influences protein adhesion. The depth profiles of MAP, obtained from angle resolved XPS, show differences in nitrogen composition with depth for MAP adsorbed to PS and POMA. Infrared spectra of hydrated adsorbed MAP revealed significant differences in the amide III region and in two bands which may originate from residues in the tandemly repeated sequences of MAP. This data demonstrates that the chemistry of the polymer film that is present at the protein-polymer interface can influence protein-protein and protein-surface interactions.

  17. A first-principles core-level XPS study on the boron impurities in germanium crystal

    SciTech Connect

    Yamauchi, Jun; Yoshimoto, Yoshihide; Suwa, Yuji

    2013-12-04

    We systematically investigated the x-ray photoelectron spectroscopy (XPS) core-level shifts and formation energies of boron defects in germanium crystals and compared the results to those in silicon crystals. Both for XPS core-level shifts and formation energies, relationship between defects in Si and Ge is roughly linear. From the similarity in the formation energy, it is expected that the exotic clusters like icosahedral B12 exist in Ge as well as in Si.

  18. A first-principles core-level XPS study on the boron impurities in germanium crystal

    NASA Astrophysics Data System (ADS)

    Yamauchi, Jun; Yoshimoto, Yoshihide; Suwa, Yuji

    2013-12-01

    We systematically investigated the x-ray photoelectron spectroscopy (XPS) core-level shifts and formation energies of boron defects in germanium crystals and compared the results to those in silicon crystals. Both for XPS core-level shifts and formation energies, relationship between defects in Si and Ge is roughly linear. From the similarity in the formation energy, it is expected that the exotic clusters like icosahedral B12 exist in Ge as well as in Si.

  19. [Vibrational spectrum and XPS contrastive studies on pyrochlore-type oxygen-rich Ce2Zr2O8 and oxygen-defective Nd2Zr2O7 phases].

    PubMed

    Xie, Hua; Wang, Lie-lin; Luo, De-li; Chen, Min

    2014-06-01

    Pyrochlore-type oxygen-rich Ce2Zr2O8 phase was prepared successfully by graphite reduction method. With the oxygen[U8]-defective Nd2Zr2O7 substituting for the oxidized precursor phase CeZrO3.5+Δ was carried out the structure comparative analysis with Ce2Zr2O8. The X-ray diffraction (XRD), Raman spectroscopy (Raman), infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the crystal structure of samples. The XRD experimental results show that Ce2Zr2O8 bulk phase contains the typical structure of pyrochlore, the superstructure peaks that characterize Ce/Zr cations ordering arrangement are very obvious, but the Zr-O ligands had also transformed from octahedrons of the co-top connection in the precursor to cubes of co-edge connection in the Ce2Zr2O8, and the formation of [ZrO8] ligand reduced greatlly the structural stability of Ce2Zr2O8 phase. Raman and IR results show that vibrational spectra bands of Ce2Zr2O8 phase increased significantly, meaning that the enriched oxygen ions result in a removal of the degeneracy peak for Ce2Zr2O8 phase, which confirms further the structural symmetry of Ce2Zr2O8 phase lower than its precursor. XPS results show that Ce (IV) characteristic peak (916.3 eV) in the Ce2Zr2O8 phase surface is very obvious. No the appearance of Ce (III) peak (885 eV) suggests that Ce3+ from the precursor has been completely oxidized into Ce4+ in the Ce2Zr2O8 phase; the Zr(3d) binding energy is close to fluorite phase with Zr4+, which confirms that [ZrO8] ligand in the Ce2Zr2O8 surface is consistent with the bulk phase. The increasing low binding energy of O(1s) shows that oxygen species in the Ce2Zr2O8 bulk phase are between lattice oxygen and adsorbed oxygen, the presence of high oxygen peak suggests that the surface of Ce2Zr2O8 contains adsorbed oxygen, and the bonding strength between adsorption oxygen and Ce2Zr2O8 bulk phase is between CeO2 and Nd2Zr2O7.

  20. A combined QCM and XPS investigation of asphaltene adsorption on metal surfaces.

    PubMed

    Rudrake, Amit; Karan, Kunal; Horton, J Hugh

    2009-04-01

    To investigate asphaltene-metal interactions, a combined quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS) study of asphaltene adsorption on a gold surface was conducted. Adsorption experiments were conducted at 25 degrees C with solutions of asphaltenes in toluene at concentrations ranging from 50 to 1500 ppm. QCM measurements yielded information on the kinetics of adsorption and further assessment of the data allowed the estimation of equilibrium adsorption levels. XPS analysis of adsorbed and bulk asphaltene demonstrated the presence of carboxylic, thiophenic, sulfide, pyridinic and pyrrolic type functional groups. The intensity of the main carbon (C-H) peak was related to surface coverage of adsorbed asphaltene as a function of asphaltene concentration by a simple mathematical model. The mass adsorption data from the QCM experiments also allowed estimation of the surface coverage, which was compared to those from XPS analyses. Surface coverage estimates as a function of asphaltene concentration could be described by a Langmuir (type-I) isotherm. The free energy of asphaltene adsorption was estimated to be -26.8+/-0.1 and -27.3+/-0.1 kJ/mol from QCM and XPS data, respectively assuming asphaltene molar mass of 750 g/gmol. QCM and XPS data was also analyzed to estimate adsorbed layer thickness after accounting for surface coverage. The thickness of the adsorbed asphaltene estimated from both XPS and QCM data analyses ranged from 6-8 nm over the entire range of adsorption concentrations investigated.

  1. A Multi-technique Characterization of Adsorbed Protein Films: Orientation and Structure by ToF-SIMS, NEXAFS, SFG, and XPS

    NASA Astrophysics Data System (ADS)

    Baio, Joseph E.

    There are many techniques that allow surface scientists to study interfaces. However, few are routinely applied to probe biological surfaces. The work presented here demonstrates how detailed information about the conformation, orientation, chemical state, and molecular structure of biological molecules immobilized onto a surface can be assessed by electron spectroscopy, mass spectrometry, and nonlinear vibrational spectroscopy techniques. This investigation began with the development of simple model systems (small proteins, and peptides) and evolved into a study of more complex --- real world systems. Initially, two model systems based on the chemical and electrostatic immobilization of a small rigid protein (Protein G B1 domain, 6kDa) were built to develop the capabilities of time-of-flight secondary ion mass spectrometry (ToFSIMS), near edge X-ray absorption fine structure spectroscopy (NEXAFS) and sum frequency generation (SFG) spectroscopy as tools to probe the structure of surface immobilized proteins. X-ray photoelectron spectroscopy (XPS) was used to measure the amount of immobilized protein and ToF-SIMS sampled the amino acid composition of the exposed surface of the protein film. Within the ToF-SIMS spectra, an enrichment of secondary ions from amino acids located at opposite ends of the proteins were used to describe protein orientation. SFG spectral peaks characteristic of ordered alpha-helix and beta-sheet elements were observed for both systems and the phase of the peaks indicated a predominantly upright orientation for both the covalent and electrostatic configurations. Polarization dependence of the NEXAFS signal from the N 1s to pi* transition of the peptide bonds that make up the beta-sheets also indicated protein ordering at the surface. Building upon the Protein G B1 studies, the orientation and structure of a surface immobilized antibody (HuLys Fv: variant of humanized anti-lysozyme variable fragment, 26kDa) was characterized across two

  2. XPS and SIMS study of the surface and interface of aged C+ implanted uranium

    DOE PAGES

    Donald, Scott B.; Siekhaus, Wigbert J.; Nelson, Art J.

    2016-09-08

    X-ray photoelectron spectroscopy in combination with secondary ion mass spectrometry depth profiling were used to investigate the surface and interfacial chemistry of C+ ion implanted polycrystalline uranium subsequently oxidized in air for over 10 years at ambient temperature. The original implantation of 33 keV C+ ions into U238 with a dose of 4.3 × 1017 cm–3 produced a physically and chemically modified surface layer that was characterized and shown to initially prevent air oxidation and corrosion of the uranium after 1 year in air at ambient temperature. The aging of the surface and interfacial layers were examined by using themore » chemical shift of the U 4f, C 1s, and O 1s photoelectron lines. In addition, valence band spectra were used to explore the electronic structure of the aged carbide surface and interface layer. Moreover, the time-of-flight secondary ion mass spectrometry depth profiling results for the aged sample confirmed an oxidized uranium carbide layer over the carbide layer/U metal interface.« less

  3. Electron Dynamics at Dye-Semiconductor Interfaces probed with Picosecond Time-Resolved XPS

    NASA Astrophysics Data System (ADS)

    Neppl, Stefan; Shavorskiy, Andrey; Zegkinoglou, Ioannis; Fraund, Matthew; Salmeron, Miquel; Guo, Jinghua; Bluhm, Hendrik; Gessner, Oliver

    2014-05-01

    Picosecond time-resolved core-level spectroscopy using laser pulses to initiate and short X-ray pulses to probe photo-induced processes have the unique potential to provide electronic state- and atomic site-specific insight into fundamental electron dynamics in complex systems. Up to now, however, most of these experiments have concentrated on the electronic and structural dynamics in isolated or solvated molecules. Here we report preliminary results of a time-resolved X-ray photoelectron spectroscopy (TRXPS) study with the goal to follow the light-driven electron dynamics of N3 dye molecules adsorbed on a nano-structured ZnO semiconductor substrate - a technologically pertinent system for dye-sensitized solar cells - on the pico- to nanosecond time scale from the perspective of individual atomic sites at this complex interface. A distinct evolution of the molecular C1s photoemission line shape is observed as a function of time delay between a visible (532 nm) laser pump pulse (resonant with the N3 HOMO-LUMO gap) and the X-ray probe pulses. The observed changes in the C1s TRXPS spectra will be discussed in the context of possible charge recombination and relaxation processes leading to the neutralization of the transiently oxidized dye following ultrafast photo-induced electron injection.

  4. Structural environment of uranium (VI) and europium (III) species sorbed onto phosphate surfaces: XPS and optical spectroscopy studies

    SciTech Connect

    Drot, R.; Simoni, E.; Alnot, M.; Ehrhardt, J.J.

    1998-09-15

    In order to characterize the structure of the surface complexes formed by interaction between uranyl and europium (III) ions and the surface of solid matrices, optical and X-ray photoelectron spectroscopies experiments on uranyl/europium loaded phosphate solids have been performed. The use of complimentary spectroscopic techniques allows an identification of the sorption mechanism and a structural characterization of the sorption sites and the sorbed species on phosphate surfaces. The samples were prepared from aqueous uranyl or europium solutions in the pH range from 1.5 to 6.0. The surface coverage was varied from 1 to 40% of a monolayer. The differences between the emission spectra of europium ions either sorbed on the surface of phosphate samples or doped inside the solid unambiguously indicates that these sorbed ions are exclusively located on the surface and that they do not migrate inside the matrix, which shows clearly that surface complexation is involved during the sorption process. The XPS spectrum of uranyl ions sorbed on zirconium diphosphate exhibits only one component, while the spectrum corresponding to uranium on thorium matrix shows two different unresolved peaks attributed to two different chemical environments. These results, corroborated by the uranyl emission spectra and the associated decay times and those obtained by optical spectroscopy of europium sorbed on the same solids, have been interpreted in terms of two sorption sites probably formed by the oxygens of the PO{sub 4} and P{sub 2}O{sub 7} surface groups.

  5. Combined far infrared RAIRS and XPS studies of TiCl 4 adsorption and reaction on Mg films

    NASA Astrophysics Data System (ADS)

    Pilling, M. J.; Fonseca, A. Amieiro; Cousins, M. J.; Waugh, K. C.; Surman, M.; Gardner, P.

    2005-08-01

    In recent years there has been an increase in interest in the study of model Ziegler-Natta catalysts used for the polymerisation of ethene and propene. Particular attention has focused on catalysts consisting of TiCl 4 on activated MgCl 2 accompanied by a co-catalyst, usually triethylaluminium (AlEt 3). As part of a wider project on the characterisation of model Ziegler-Natta catalysts we have investigated the interaction of TiCl 4 with metallic Mg films grown on a Au surface using X-ray photoelectron spectroscopy (XPS) and far infrared reflection absorption infrared spectroscopy. Somewhat surprisingly, the infrared spectra show little variation as a function of exposure to TiCl 4. A very broad asymmetric vibrational band grows in with maximum intensity at 382 cm -1. Three prominent low frequency shoulders are observed at approximately 360, 320, and 260 cm -1. For monolayer coverages of Mg the main band at 382 cm -1 is narrower, less asymmetric and accompanied by a prominent shoulder at 398 cm -1, which increases with increasing exposure to TiCl 4. TiCl 4 exposure in the presence of 5 × 10 -8 Torr of ethyl benzoate results in a change in line shape with low frequency broadening and a small shift in the frequency of the band. These spectra are discussed in the light of the possible constituent species making up the surface layer.

  6. Surface chemical characterization of 2.5-microm particulates (PM2.5) from air pollution in Salt Lake City using TOF-SIMS, XPS, and FTIR.

    PubMed

    Zhu, Y J; Olson, N; Beebe, T P

    2001-08-01

    Particulate matter with a diameter of 2.5 microm collected in Salt Lake City (SLC PM2.5) was studied using TOF-SIMS (time-of-flight secondary-ion mass spectrometry), XPS (X-ray photoelectron spectroscopy), and FTIR (Fourier transform infrared spectroscopy). The high spatial resolution and high surface sensitivity of TOF-SIMS allow the surfaces of individual particulates to be analyzed. The high mass-resolution of TOF-SIMS provides good separation of signals from different chemical species at the same nominal mass, and the extremely high detection sensitivity of TOF-SIMS makes the detection of trace elements possible. Metallic elements such as Li, Na, Mg, Al, K, Ca, Cr, Mn, Fe, Cu, Zn, Cs, and Bi were detected by TOF-SIMS on the surface of SLC PM25. The uranium ion U+ together with its oxide ions UO+ and UO2+ were also found. Inorganic compounds detected include oxides, hydroxides, nitrates, sulfates, silicates, borates, chlorides, etc. Organic compounds detected include hydrocarbons, alcohols, aldehydes, ethers, carboxylic acids, amines, amides, nitriles, etc. A number of polycyclic aromatic hydrocarbons (PAH) and nitrated polycyclic aromatic hydrocarbons were detected by TOF-SIMS. High-resolution XPS Cls spectrum shows functional groups such as C-O, CO2, C-CO2, C-C, and C-H and aromatic pi-pi* shake-up transitions. High-resolution XPS O 1s spectrum indicates the coexistence of different oxygen compounds on the surface of PM2.5. FTIR results confirm the presence of various organic compounds in SLC PM2.5 detected by TOF-SIMS and XPS.

  7. Surface Chemical Composition of Size-fractionated Urban Walkway Aerosols Determined by XPS and ToF-SIMS

    NASA Astrophysics Data System (ADS)

    Wenjuan, Cheng; Lu-Tao, Weng; Yongjie, Li; Arthur, Lau; Chak, Chan; Chi-Ming, Chan

    2013-04-01

    In this study, aerosol particles with sizes ranging from 0.056 to 10 ?m were collected using a ten-stage impactor sampler (MOUDI) from a busy walkway of Hong Kong. The aerosol samples of each stage were examined with X-ray photoelectron spectroscopy (XPS). Size dependent distributions of the detected six key elements (N, S, Ca, Si, O, and C) were revealed together with the chemical states of N, S and C. The results indicated that aliphatic hydrocarbons were the dominant species on the surface of all particles while a small portion of graphitic carbon (due to elemental and aromatic hydrocarbons) was also detected on the surface of the particles with sizes ranging from 0.056 to 0.32 ?m. Organic oxygen- and nitrogen-containing surface groups as well as sulfates were more abundant on the surface of the particles with sizes ranging from 0.32 to 1 μm. Organic oxygen- and nitrogen-containing surface groups as well as sulfates were more abundant on the surface of the particles with sizes ranging from 0.32 to 1 μm. Inorganic salts and nitrates were found in coarse-mode particles. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used for detailed surface and near surface composition analysis. Principal component analysis (PCA) of the ToF-SIMS spectra confirmed the XPS results that aromatic hydrocarbons were associated with the nucleation-mode particles. Aliphatic hydrocarbons with O- and N-containing functional groups were associated with accumulation-mode particles and inorganic salts were related to the coarse-mode particles. Depth-profiling experiments were performed on three specific sets of samples (nucleation-, accumulation- and coarse-mode particles) to study their near-surface structures. It showed that organic compounds were concentrated on the very top surface of the coarse-mode particles with inorganics in the core. The accumulation-mode particles had thick coatings of diverse organic compositions. The nucleation-mode particles, which contained

  8. Association of the Cytoplasmic Membrane Protein XpsN with the Outer Membrane Protein XpsD in the Type II Protein Secretion Apparatus of Xanthomonas campestris pv. Campestris

    PubMed Central

    Lee, Hsien-Ming; Wang, Kuan-Cheng; Liu, Yi-Ling; Yew, Hsin-Yan; Chen, Ling-Yun; Leu, Wei-Ming; Chen, David Chanhen; Hu, Nien-Tai

    2000-01-01

    An xps gene cluster composed of 11 open reading frames is required for the type II protein secretion in Xanthomonas campestris pv. campestris. Immediately upstream of the xpsD gene, which encodes an outer membrane protein that serves as the secretion channel by forming multimers, there exists an open reading frame (previously designated ORF2) that could encode a protein of 261 amino acid residues. Its N-terminal hydrophobic region is a likely membrane-anchoring sequence. Antibody raised against this protein could detect in the wild-type strain of X. campestris pv. campestris a protein band with an apparent molecular mass of 36 kDa by Western blotting. Its aberrant slow migration in sodium dodecyl sulfate-polyacrylamide gels might be due to its high proline content. We designated this protein XpsN. By constructing a mutant strain with an in-frame deletion of the chromosomal xpsN gene, we demonstrated that it is required for the secretion of extracellular enzyme by X. campestris pv. campestris. Subcellular fractionation studies indicated that the XpsN protein was tightly associated with the membrane. Sucrose gradient sedimentation followed by immunoblot analysis revealed that it primarily appeared in the cytoplasmic membrane fractions. Immune precipitation experiments indicated that the XpsN protein was coprecipitated with the XpsD protein. In addition, the XpsN protein was co-eluted with the (His)6-tagged XpsD protein from the metal affinity chromatography column. All observations suggested that the XpsN protein forms a stable complex with the XpsD protein. In addition, immune precipitation analysis of the XpsN protein with various truncated XpsD proteins revealed that the C-terminal region of the XpsD protein between residues 650 and 759 was likely to be involved in complex formation between the two. PMID:10692359

  9. XPS Study of Ion Irradiated and Unirradiated UO2 Thin Films.

    PubMed

    Teterin, Yury A; Popel, Aleksej J; Maslakov, Konstantin I; Teterin, Anton Yu; Ivanov, Kirill E; Kalmykov, Stepan N; Springell, Ross; Scott, Thomas B; Farnan, Ian

    2016-08-15

    XPS determination of the oxygen coefficient kO = 2 + x and ionic (U(4+), U(5+), and U(6+)) composition of oxides UO2+x formed on the surfaces of differently oriented (hkl) planes of thin UO2 films on LSAT (Al10La3O51Sr14Ta7) and YSZ (yttria-stabilized zirconia) substrates was performed. The U 4f and O 1s core-electron peak intensities as well as the U 5f relative intensity before and after the (129)Xe(23+) and (238)U(31+) irradiations were employed. It was found that the presence of uranium dioxide film in air results in formation of oxide UO2+x on the surface with mean oxygen coefficients kO in the range 2.07-2.11 on LSAT and 2.17-2.23 on YSZ substrates. These oxygen coefficients depend on the substrate and weakly on the crystallographic orientation. On the basis of the spectral parameters it was established that uranium dioxide films AP2,3 on the LSAT substrates have the smallest kO values, and from the XRD and EBSD results it follows that these samples have a regular monocrystalline structure. The XRD and EBSD results indicate that samples AP5-7 on the YSZ substrates have monocrystalline structure; however, they have the highest kO values. The observed difference in the kO values was probably caused by the different nature of the substrates: the YSZ substrates provide 6.4% compressive strain, whereas (001) LSAT substrates result only in 0.03% tensile strain in the UO2 films. (129)Xe(23+) irradiation (92 MeV, 4.8 × 10(15) ions/cm(2)) of uranium dioxide films on the LSAT substrates was shown to destroy both long-range ordering and uranium close environment, which results in an increase of uranium oxidation state and regrouping of oxygen ions in uranium close environment. (238)U(31+) (110 MeV, 5 × 10(10), 5 × 10(11), 5 × 10(12) ions/cm(2)) irradiations of uranium dioxide films on the YSZ substrates were shown to form the lattice damage only with partial destruction of the long-range ordering.

  10. Comparing XPS and ToF-ERDA measurement of high-k dielectric materials

    NASA Astrophysics Data System (ADS)

    Martin, D. M.; Enlund, J.; Kappertz, O.; Jensen, J.

    2008-03-01

    Compositional analysis of aluminium oxy-nitride (AlON) films deposited by reactive magnetron sputtering was performed using time-of-flight elastic recoil detection analysis (ToF-ERDA) and X-ray photoelectron spectroscopy (XPS) with sputter profiling. The composition profiles of the films depend on deposition conditions. The benefits of the different analytical methods are discussed and comparison of the profiles is performed. Conversion of the depth scale from XPS sputter time to a nm scale is implemented and the ToF-ERDA profile fitted. Densities of the deposited AlON films are calculated indicating differing film quality in agreement with the composition profile extracted.

  11. New Observations of Soft X-ray (0.5-5 keV) Solar Spectra

    NASA Astrophysics Data System (ADS)

    Caspi, A.; Woods, T. N.; Mason, J. P.; Jones, A. R.; Warren, H. P.

    2013-12-01

    The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable on many time scales. However, the actual solar soft X-ray (SXR) (0.5-5 keV) spectrum is not well known, particularly during solar quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include high-resolution but very narrow-band spectra from crystal spectrometers (e.g., Yohkoh/BCS), or integrated broadband irradiances from photometers (e.g., GOES/XRS, TIMED/XPS, etc.) that lack detailed spectral information. In recent years, broadband measurements with moderate energy resolution (~0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and SAX on MESSENGER, although they did not extend to energies below ~1 keV. We present observations of solar SXR emission obtained using new instrumentation flown on recent SDO/EVE calibration rocket underflights. The photon-counting spectrometer, a commercial Amptek X123 with a silicon drift detector and an 8 μm Be window, measures the solar disk-integrated SXR emission from ~0.5 to >10 keV with ~0.15 keV FWHM resolution and 1 s cadence. A novel imager, a pinhole X-ray camera using a cooled frame-transfer CCD (15 μm pixel pitch), Ti/Al/C filter, and 5000 line/mm Au transmission grating, images the full Sun in multiple spectral orders from ~0.1 to ~5 nm with ~10 arcsec/pixel and ~0.01 nm/pixel spatial and spectral detector scales, respectively, and 10 s cadence. These instruments are prototypes for future CubeSat missions currently being developed. We present new results of solar observations on 04 October 2013 (NASA sounding rocket 36.290). We compare with previous results from 23 June 2012 (NASA sounding rocket 36.286), during which solar activity was low and no signal was observed above ~4 keV. We compare our spectral and imaging measurements with spectra and broadband irradiances from other instruments, including SDO/EVE, GOES/XRS, TIMED/XPS

  12. Reactor Neutrino Spectra

    NASA Astrophysics Data System (ADS)

    Hayes, Anna C.; Vogel, Petr

    2016-10-01

    We present a review of the antineutrino spectra emitted from reactors. Knowledge of these spectra and their associated uncertainties is crucial for neutrino oscillation studies. The spectra used to date have been determined either by converting measured electron spectra to antineutrino spectra or by summing over all of the thousands of transitions that make up the spectra, using modern databases as input. The uncertainties in the subdominant corrections to β-decay plague both methods, and we provide estimates of these uncertainties. Improving on current knowledge of the antineutrino spectra from reactors will require new experiments. Such experiments would also address the so-called reactor neutrino anomaly and the possible origin of the shoulder observed in the antineutrino spectra measured in recent high-statistics reactor neutrino experiments.

  13. Fully Sulfonated Polyaniline (NSPAN)(We thank Mitsubishi Rayon for samples.) and Aluminum Interface: an XPS Study

    NASA Astrophysics Data System (ADS)

    Smallfield, J. A. O.; Fahlman, M.; Epstein, A. J.

    2000-03-01

    We report the results of XPS experiments in which aluminum was evaporated onto NSPAN. Data for pristine NSPAN shows two N1s peaks centered at ~399.3 eV and ~401.3 eV, with an area ratio of ~0.46:0.54. These peaks are assigned to amine and protonated imine nitrogens, respectively. The area ratio is consistent with the emeraldine salt state of polyaniline with strong localization in bipolaron form, as independently determined by magnetic studies.(W. Lee, G. Du, A.J. Epstein, S. Shimizu, T. Saitoh, and M. Uzawa, Synth. Met. 84), 807 (1997). With increasing aluminum deposition, the amine and protonated imine peak positions remain fixed, while the amine to imine ratio increases to ~0.70:0.30. This is consistent with charge donation from aluminum to NSPAN across the interface. Pristine NSPAN shows two S2p peaks centered at ~167.2 eV and ~168.5 eV in a ratio of ~0.75:0.25, each with a high binding energy shoulder, as expected for a 2p split line. These peaks are attributed to SO_3^- and SO_3H, respectively. With increasing aluminum deposition, the S2p envelope broadens, indicating a variety of chemical environments for sulfur. The possible role of hydrogen bonding to methoxy or other moities in NSPAN will be discussed.

  14. Ultrafast Dynamics in Postcollision Interaction after Multiple Auger Decays in Argon 1s Photoionization

    NASA Astrophysics Data System (ADS)

    Guillemin, R.; Sheinerman, S.; Bomme, C.; Journel, L.; Marin, T.; Marchenko, T.; Kushawaha, R. K.; Trcera, N.; Piancastelli, M. N.; Simon, M.

    2012-07-01

    Argon 1s photoionization followed by multiple Auger decays is investigated both experimentally, by means of photoelectron-ion coincidences, and theoretically. A strong influence of the different Auger decays on the photoelectron spectra is observed through postcollision interaction which shifts the maximum of the energy distribution and distorts the spectral shape. A good agreement between the calculated and measured spectra for selected Arn+ ions (n=1-5) allows one to estimate the widths (lifetimes) of the intermediate states for each specific decay pathway.

  15. Surface study of stainless steel electrode deposition from soil electrokinetic (EK) treatment using X-ray photoelectron spectroscopy (XPS)

    SciTech Connect

    Embong, Zaidi; Johar, Saffuwan; Tajudin, Saiful Azhar Ahmad; Sahdan, Mohd Zainizan

    2015-04-29

    Electrokinetic (EK) remediation relies upon application of a low-intensity direct current through the soil between stainless steel electrodes that are divided into a cathode array and an anode array. This mobilizes charged species, causing ions and water to move toward the electrodes. Metal ions and positively charged organic compounds move toward the cathode. Anions such as chloride, fluoride, nitrate, and negatively charged organic compounds move toward the anode. Here, this remediation techniques lead to a formation of a deposition at the both cathode and anode surface that mainly contributed byanion and cation from the remediated soil. In this research, Renggam-Jerangau soil species (HaplicAcrisol + RhodicFerralsol) with a surveymeter reading of 38.0 ± 3.9 μR/hr has been investigation in order to study the mobility of the anion and cation under the influence electric field. Prior to the EK treatment, the elemental composition of the soil and the stainless steel electrode are measured using XRF analyses. Next, the soil sample is remediated at a constant electric potential of 30 V within an hour of treatment period. A surface study for the deposition layer of the cathode and anode using X-ray Photoelectron spectroscopy (XPS) revealed that a narrow photoelectron signal from oxygen O 1s, carbon, C 1s silica, Si 2p, aluminium, Al 2p and chromium, Cr 2p exhibited on the electrode surface and indicate that a different in photoelectron intensity for each element on both electrode surface. In this paper, the mechanism of Si{sup 2+} and Al{sup 2+} cation mobility under the influence of voltage potential between the cathode and anode will be discussed in detail.

  16. Enhanced the photocatalytic activity of Ni-doped ZnO thin films: Morphological, optical and XPS analysis

    NASA Astrophysics Data System (ADS)

    Abdel-wahab, M. Sh.; Jilani, Asim; Yahia, I. S.; Al-Ghamdi, Attieh A.

    2016-06-01

    Pure and Ni-doped ZnO thin films with different concentration of Ni (3.5 wt%, 5 wt%, 7 wt%) were prepared by DC/RF magnetron sputtering technique. The X-rays diffraction pattern showed the polycrystalline nature of pure and Ni-doped ZnO thin films. The surface morphology of pure and Ni doped ZnO thin films were investigated through atomic force microscope, which indicated the increase in the grain dimension and surface roughness with increasing the Ni doping. The UV-Visible transmission spectra showed the decrease in the transmittance of doped ZnO thin films with the incorporation of Ni dopants. The surface and chemical state analysis of pure and Ni doped ZnO thin films were investigated by X-rays photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by an aqueous solution of methyl green dye. The tungsten lamp of 500 W was used as a source of visible light for photocatalytic study. The degradation results showed that the Ni-doped ZnO thin films exhibit highly enhanced photocatalytic activity as compared to the pure ZnO thin films. The enhanced photocatalytic activities of Ni-doped ZnO thin films were attributed to the enhanced surface area (surface defects), surface roughness and decreasing the band gap of Ni-doped ZnO thin films. Our work supports the applications of thin film metal oxides in waste water treatment.

  17. Sputter-induced erosion of alkali metal surfaces - AES, XPS and SIMS studies

    SciTech Connect

    Krauss, A.R.

    1982-01-01

    This paper will discuss the manner in which the techniques of Auger-electron spectroscopy (AES), X-ray-photoelectron spectroscopy (XPS), secondary-ion mass spectroscopy (SIMS) and ion-scattering spectroscopy (ISS) may be used to study the use of high secondary-ion-yield surfaces as a means of reducing plasma-impurity influx in magnetic-confinement fusion devices.

  18. X-ray Photoelectron Spectroscopy (XPS), Rutherford Back Scattering (RBS) studies

    NASA Technical Reports Server (NTRS)

    Neely, W. C.; Bozak, M. J.; Williams, J. R.

    1993-01-01

    X-ray photoelectron spectroscopy (XPS), Rutherford Back Scattering (RBS) studies of each of sample received were completed. Since low angle X-ray could not be performed because of instrumentation problems, Auger spectrometry was employed instead. The results of these measurements for each of the samples is discussed in turn.

  19. Deteriorated hardened cement paste structure analyzed by XPS and {sup 29}Si NMR techniques

    SciTech Connect

    Kurumisawa, Kiyofumi; Nawa, Toyoharu; Owada, Hitoshi; Shibata, Masahito

    2013-10-15

    In this report, X-ray photoelectron spectroscopy (XPS) and {sup 29}Si-MAS-NMR was used for the evaluation of deteriorated hardened cement pastes. The deterioration by ammonium nitrate solution was accompanied by changes in the pore structure as well as by structural changes in the C–S–H in the hardened cement paste. The CaO/SiO{sub 2} ratio of the C–S–H decreased with the progress of deterioration, there was also polymerization of the silicate in the C–S–H. It was confirmed that the degree of polymerization of silicate of the C–S–H in hardened cement paste can be determined by XPS. It was also shown that the polymerization depends on the structure of the C–S–H. -- Highlights: •The polymerization of silicate of the C–S–H in the HCP can be observed by XPS. •The structure of C–S–H changed with the degree of calcium leaching. •The NMR result about silicate in C–S–H was in good agreement with the XPS result.

  20. Calculation of 3s photoemission spectra of vanadium on graphite

    SciTech Connect

    Krueger, P.; Taguchi, M.; Parlebas, J.C.; Kotani, A.

    1997-06-01

    A few years ago, a satellite structure in the vanadium 3s x-ray photoemission spectroscopy (XPS) spectrum of V clusters upon graphite was observed and attributed to the presence of magnetic moments on the V surface. Here, we present calculations of these spectra using a cluster model that takes into account intra-atomic d-d and d{endash}core electron correlation and hybridization between V d and graphite {pi} states. When the V-graphite distance is increased from 1.5 to 2.0 {Angstrom} the system undergoes a low-to-high spin transition, which is clearly evidenced in the evolution of the XPS line shape. Although direct comparison with experiment is difficult, our study suggests that the observed satellite is due to core hole screening rather than a magnetic moment on the V atom. {copyright} {ital 1997} {ital The American Physical Society}

  1. Satellite structure in the Argon 1s photoelectron spectrum

    SciTech Connect

    Azuma, Y.; LeBrun, T.; MacDonald, M.; Southworth, S.H.

    1995-08-01

    Atomic inner-shell photoelectron spectra typically display several relatively weak {open_quotes}satellite peaks{close_quotes} at higher ionization energy than the primary peak. Such satellite peaks are associated with final-state configurations corresponding to ionization of an inner-shell electron and excitation or ionization of one or more valence electrons. The observation of satellite peaks demonstrates that the independent-electron picture is inadequate to describe atomic structure and the photoionization process. The measured energies and intensities of photoelectron satellites provide sensitive tests of many-electron theoretical models. We recorded the Ar 1s photoelectron spectrum on beam line X-24A at an X-ray energy of 3628 eV. The primary peak at 3206 eV ionization energy was recorded at an observed resolution of 1.8 eV (FWHM). The satellite structure shows remarkable similarity to that recorded in the suprathreshold region of the Ar K photoabsorption cross section, demonstrating the manner in which these techniques complement each other. Surprisingly, while the region just above the K threshold in Ar was the subject of several theoretical studies using multi-configuration calculations, we find good agreement between our results and those of Dyall and collaborators using a shake model.

  2. CoOx thin film deposited by CVD as efficient water oxidation catalyst: change of oxidation state in XPS and its correlation to electrochemical activity.

    PubMed

    Weidler, Natascha; Paulus, Sarina; Schuch, Jona; Klett, Joachim; Hoch, Sascha; Stenner, Patrick; Maljusch, Artjom; Brötz, Joachim; Wittich, Carolin; Kaiser, Bernhard; Jaegermann, Wolfram

    2016-04-28

    To reduce energy losses in water electrolysers a fundamental understanding of the water oxidation reaction steps is necessary to design efficient oxygen evolution catalysts. Here we present CoOx/Ti electrocatalytic films deposited by thermal and plasma enhanced chemical vapor deposition (CVD) onto titanium substrates. We report electrochemical (EC), photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements. The electrochemical behavior of the samples was correlated with the chemical and electronic structure by recording XPS spectra before and after each electrochemical treatment (conditioning and cyclovoltammetry). The results show that the electrochemical behavior of CoOx/Ti strongly depends on the resulting electronic structure and composition. The thermal deposition leads to the formation of a pure Co(II)Ox which transforms to a mixed Co(II)Co(III)Ox during the OER. This change in oxidation state is coupled with a decrease in overpotential from η = 0.57 V to η = 0.43 V at 5 mA cm(-2). Plasma deposition in oxygen leads to a Co(III)-dominated mixed CoOx, that has a lower onset potential as deposited due to a higher Co(III) content in the initial deposited material. After the OER XPS results of the CoOx/Ti indicate a partial formation of hydroxides and oxyhydroxides on the oxide surface. Finally the plasma deposition in air, results in a CoOxOH2 surface, that is able to completely oxidizes during OER to an oxyhydroxide Co(III)OOH. With the in situ formed CoOOH we present a highly active catalyst for the OER (η = 0.34 at 5 mA cm(-2); η = 0.37 V at 10 mA cm(-2)).

  3. Surface Coverage and Structure of Mixed DNA/Alkylthiol Monolayers on Gold: Characterization by XPS, NEXAFS, and Fluorescence Intensity Measurements

    PubMed Central

    Lee, Chi-Ying; Gong, Ping; Harbers, Gregory M.; Grainger, David W.; Castner, David G.; Gamble, Lara J.

    2006-01-01

    Self-assembly of thiol-terminated single-stranded DNA (HS-ssDNA) on gold has served as an important model system for DNA immobilization at surfaces. Here, we report a detailed study of the surface composition and structure of mixed self-assembled DNA monolayers containing a short alkylthiol surface diluent [11-mercapto-1-undecanol (MCU)] on gold supports. These mixed DNA monolayers were studied with X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and fluorescence intensity measurements. XPS results on sequentially adsorbed DNA/MCU monolayers on gold indicated that adsorbed MCU molecules first incorporate into the HS-ssDNA monolayer and, upon longer MCU exposures, displace adsorbed HS-ssDNA molecules from the surface. Thus, HS-ssDNA surface coverage steadily decreased with MCU exposure time. Polarization-dependent NEXAFS and fluorescence results both show changes in signals consistent with changes in DNA orientation after only 30 min of MCU exposure. NEXAFS polarization dependence (followed by monitoring the N 1s → π* transition) of the mixed DNA monolayers indicated that the DNA nucleotide base ring structures are oriented more parallel to the gold surface compared to DNA bases in pure HS-ssDNA monolayers. This indicates that HS-ssDNA oligomers reorient toward a more-upright position upon MCU incorporation. Fluorescence intensity results using end-labeled DNA probes on gold show little observable fluorescence on pure HS-ssDNA monolayers, likely due to substrate quenching effects between the fluorophore and the gold. MCU diluent incorporation into HS-ssDNA monolayers initially increases DNA fluorescence signal by densifying the chemisorbed monolayer, prompting an upright orientation of the DNA, and moving the terminal fluorophore away from the substrate. Immobilized DNA probe density and DNA target hybridization in these mixed DNA monolayers, as well as effects of MCU diluent on DNA hybridization in complex

  4. Surface Coverage and Structure of Mixed DNA/Alkylthiol Monolayers on Gold: Characterization by XPS, NEXAFS, and Fluorescence Intensity Measurements

    SciTech Connect

    Lee,C.; Gong, P.; Harbers, G.; Grainger, D.; Castner, D.; Gamble, L.

    2006-01-01

    Self-assembly of thiol-terminated single-stranded DNA (HS-ssDNA) on gold has served as an important model system for DNA immobilization at surfaces. Here, we report a detailed study of the surface composition and structure of mixed self-assembled DNA monolayers containing a short alkylthiol surface diluent [11-mercapto-1-undecanol (MCU)] on gold supports. These mixed DNA monolayers were studied with X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), and fluorescence intensity measurements. XPS results on sequentially adsorbed DNA/MCU monolayers on gold indicated that adsorbed MCU molecules first incorporate into the HS-ssDNA monolayer and, upon longer MCU exposures, displace adsorbed HS-ssDNA molecules from the surface. Thus, HS-ssDNA surface coverage steadily decreased with MCU exposure time. Polarization-dependent NEXAFS and fluorescence results both show changes in signals consistent with changes in DNA orientation after only 30 min of MCU exposure. NEXAFS polarization dependence (followed by monitoring the N 1s{yields}{pi}* transition) of the mixed DNA monolayers indicated that the DNA nucleotide base ring structures are oriented more parallel to the gold surface compared to DNA bases in pure HS-ssDNA monolayers. This indicates that HS-ssDNA oligomers reorient toward a more-upright position upon MCU incorporation. Fluorescence intensity results using end-labeled DNA probes on gold show little observable fluorescence on pure HS-ssDNA monolayers, likely due to substrate quenching effects between the fluorophore and the gold. MCU diluent incorporation into HS-ssDNA monolayers initially increases DNA fluorescence signal by densifying the chemisorbed monolayer, prompting an upright orientation of the DNA, and moving the terminal fluorophore away from the substrate. Immobilized DNA probe density and DNA target hybridization in these mixed DNA monolayers, as well as effects of MCU diluent on DNA hybridization in

  5. Incorporation of low energy activated nitrogen onto HOPG surface: Chemical states and thermal stability studies by in-situ XPS and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chandran, Maneesh; Shasha, Michal; Michaelson, Shaul; Hoffman, Alon

    2016-09-01

    In this paper we report the chemical states analysis of activated nitrogen incorporated highly oriented pyrolytic graphite (HOPG) surface under well-controlled conditions. Nitrogen incorporation is carried out by two different processes: an indirect RF nitrogen plasma and low energy (1 keV) N2+ implantation. Bonding configuration, concentration and thermal stability of the incorporated nitrogen species by aforesaid processes are systematically compared by in-situ X-ray photoelectron spectroscopy (XPS). Relatively large concentration of nitrogen is incorporated onto RF nitride HOPG surface (16.2 at.%), compared to N2+ implanted HOPG surface (7.7 at.%). The evolution of N 1s components (N1, N2, N3) with annealing temperature is comprehensively discussed, which indicates that the formation and reorganization of local chemical bonding states are determined by the process of nitridation and not by the prior chemical conditioning (i.e., amorphization or hydrogenation) of the HOPG surface. A combined XPS and Raman spectroscopy studies revealed that N2+ implantation process resulted in a high level of defects to the HOPG surface, which cannot be annealed-out by heat treatment up to 1000 °C. On the other hand, the RF nitrogen plasma process did not produce a high level of surface defects, while incorporating nearly the same amount of stable nitrogen species.

  6. Weak decays of J/\\psi and {\\rm{\\Upsilon }}(1S)

    NASA Astrophysics Data System (ADS)

    Wang, Tianhong; Jiang, Yue; Yuan, Han; Chai, Kan; Wang, Guo-Li

    2017-04-01

    In this paper we study the weak decays of J/\\psi and {{\\Upsilon }}(1S). The cases when the final mesons are pseudo-scalars or vectors are considered. Using the Bethe–Salpeter method, we calculate the hadronic transition amplitude and give the form factors. The energy spectra of leptons for the semi-leptonic channels are also presented for convenience. In the calculation of non-leptonic decays, the naive factorization is applied. And all types of such channels, namely, flavor-favored or suppressed and color-favored or suppressed, are calculated. Our results show that, for the semi-leptonic decay modes, the largest branching ratios are of the order of 10‑10 both for J/\\psi and {{\\Upsilon }}(1S) decays, and the largest branching ratios of non-leptonic decays are of the order of 10‑9 for J/\\psi and 10‑10 for {{\\Upsilon }}(1S).

  7. Measurement of the 1s2s 1S0-1s2p 3P1 intercombination interval in helium-like silicon.

    PubMed

    Redshaw, M; Myers, E G

    2002-01-14

    Using Doppler-tuned fast-beam laser spectroscopy the 1s2s 1S0-1s2p 3P1 intercombination interval in 28Si12+ has been measured to be 7230.5(2) cm(-1). The experiment made use of a single-frequency Nd:YAG (1.319 microm) laser and a high-finesse optical buildup cavity. The result provides a precision test of modern relativistic and QED atomic theory.

  8. Crack spectra analysis

    SciTech Connect

    Tiernan, M.

    1980-09-01

    Crack spectra derived from velocity data have been shown to exhibit systematics which reflect microstructural and textural differences between samples (Warren and Tiernan, 1980). Further research into both properties and information content of crack spectra have yielded the following: Spectral features are reproducible even at low pressures; certain observed spectral features may correspond to non-in-situ crack populations created during sample retrieval; the functional form of a crack spectra may be diagnostic of the sample's grain texture; hysteresis is observed in crack spectra between up and down pressure runs - it may be due to friction between the faces of closed crack populations.

  9. Photographic spectra of fireballs

    NASA Astrophysics Data System (ADS)

    Borovička, J.

    2016-01-01

    Two methods of spectroscopy of meteors using image intensified video cameras and classical photographic film cameras are compared. Video cameras provide large number of low resolution spectra of meteors of normal brightness, which can be used for statistical studies. Large format film cameras have been used through the history and provide high resolution spectra, which can be used to derive temperature, density and absolute abundances of various elements in the radiating plasma. The sensitivity of films is, however, low and only spectra of bright meteors (fireballs) can be studied. Examples of photographic fireball spectra are provided.

  10. New Pt/Alumina model catalysts for STM and in situ XPS studies

    NASA Astrophysics Data System (ADS)

    Nartova, Anna V.; Gharachorlou, Amir; Bukhtiyarov, Andrey V.; Kvon, Ren I.; Bukhtiyarov, Valerii I.

    2017-04-01

    The new Pt/alumina model catalysts for STM and in situ XPS studies based on thin alumina film formed over the conductive substrate are proposed. Procedure of platinum deposition developed for porous alumina was adapted for the model alumina support. The set of Pt/AlOx-film samples with the different mean platinum particle size was prepared. Capabilities of in situ XPS investigations of the proposed catalysts were demonstrated in study of NO decomposition on platinum nanoparticles. It is shown that proposed model catalysts behave similarly to Pt/γ-Al2O3 and provide the new opportunities for the instrumental studies of platinum catalysts due to resolving several issues (charging, heating, screening) that are typical for the investigation of the porous oxide supported catalysts.

  11. XPS and EDX study on an RuKL zeolite hydrogenation catalyst

    NASA Astrophysics Data System (ADS)

    Liu, You Ying; Zhao, Weijun; Zhang, Shuji; Fang, Yanquan

    Among several zeolite catalysts, synthesized in our laboratories, for hydrogenation reactions, an RuKL zeolite catalyst appeared to be the best. The activity of this RuKL catalyst remained nearly constant after several hydrogenation cycles. To understand the nature of the catalyst XPS and EDX have been applied. According to the analytical results the active components in the catalyst are Ru 3+ and Ru 0.

  12. An X-Ray Photoelectron Spectroscopy (XPS) Study of Activated Carbons Impregnated with some Organocopper Complexes,

    DTIC Science & Technology

    1993-10-01

    AD-A282 721 l lllllll a Dfene Defence nationals AN X.RAY PHOTOELECTRON SPECTROSCOPY (XPS) STUDY OF ACTIVATED CARBONS IMPREGNATED WITH SOME... ammoniacal solution as a carrier into which all impregnants (except TEDA) were dissolved. Without a suitable carrier, and with the inherent low vapor...and will not be repeated here. All five complexes were synthesized at DREO using known methods. 2 2.2 IMPREGNATING PROCEDURES Two impregnating

  13. In Situ Studies of Surface Mobility on Noble Metal Model Catalysts Using STM and XPS at Ambient Pressure

    SciTech Connect

    Butcher, Derek Robert

    2010-06-01

    are present on the Pt(100) hex reconstructed phase, but not the (100)-(1x1) surface. The increase in ethylene pressure caused the adsorbate interactions to dominate the crystal morphology and imposed a surface layer structure that matched the ethylidyne binding geometry. The STM results also showed that the surface was reversibly deformed during imaging due to increases in Pt mobility at high pressure. The size dependence on the activity and surface chemistry of Rh nanoparticles was studied using AP-XPS. The activity was found to increase with particle size. The XPS spectra show that in reaction conditions the particle surface has an oxide layer which is chemically distinct from the surface structure formed by heating in oxygen alone. This surface oxide which is stabilized in the catalytically active CO oxidation conditions was found to be more prevalent on the smaller nanoparticles. The reaction-induced surface segregation behavior of bimetallic noble metal nanoparticles was observed with APXPS. Monodisperse 15 nm RhPd and PdPt nanoparticles were synthesized with well controlled Rh/Pd and Pd/Pt compositions. In-situ XPS studies showed that at 300 C in the presence of an oxidizing environment (100 mTorr NO or O2) the surface concentration of the more easily oxidized element (Rh in RhPd and Pd in PdPt) was increased. Switching the gas environment to more reducing conditions (100 mTorr NO and 100 mTorr CO) caused the surface enrichment of the element with the lowest surface energy in its metallic state. Using in-situ characterization, the redox chemistry and the surface composition of bimetallic nanoparticle samples were monitored in reactive conditions. The particle surfaces were shown to reversibly restructure in response to the gas environment at high temperature. The oxidation behavior of the Pt(110) surface was studied using surface sensitive in-situ characterization by APXPS and STM. In the presence of 500 mTorr O2 and temperatures between 25

  14. XPS investigation of titanium contact formation to ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Barnett, Chris J.; Castaing, Ambroise; Jones, Daniel R.; Lewis, Aled R.; Jenkins, Lewys J.; Cobley, Richard J.; Maffeis, Thierry G. G.

    2017-02-01

    Ti is often used to form an initial Ohmic interface between ZnO and Au due to its low work function, and the TiO2/ZnO heterojunction is also of great importance for many practical applications of nanoparticles. Here, Ti has been controllably deposited onto hydrothermally grown ZnO nanowires and the formation of metal-semiconductor contact has been investigated using x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and scanning electron microscopy. XPS results showed that that the Ti initially reacts with surface oxygen species to form TiO2, and further deposition results in the formation of oxides with oxidation state numbers lower than four, and eventually metallic Ti on top of the TiO2. The formation of TiC was also observed. XPS showed that the onset of metallic Ti coincided with a Zn 3p core level shift to lower binding energy, indicating upwards band bending and the formation of a rectifying contact. Annealing caused a near-complete conversion of the metallic Ti to TiO2 and caused the Zn 3p to shift back to its original higher binding energy, resulting in downwards band bending and a more Ohmic contact. PL measurements showed that the optical properties of the nanowires are not affected by the contact formation.

  15. XPS Investigation of Surface Secondary Phase Segregation in CIGS Thin Film

    SciTech Connect

    Al-Thani, H. A.; Abdullah, M. M.; Hasoon, F. S.

    2011-01-01

    Cu(In, Ga)Se{sub 2} (CIGS) thin films were deposited on Molybdenum (Mo) coated soda lime glass (SLG/Mo) substrates, using physical vapor deposition (PVD) 3-stage process. The Mo thin films were sputtered on SLG substrates using DC planar magnetron sputtering at a working gas (Ar) pressure that varies from 0.8 mT to 12 mT with a sputtering power density of 1.2 W/cm{sub 2}. The sputtering pressure of Mo thin films was varied in order to induce variations in the sputtered films morphology and porosity; as well as to subsequently induce variations in the Na out-diffusion from SLG substrate. The surface chemistry of CIGS thin films was investigated by X-Ray Photoelectron Spectroscopy (XPS). The XPS surface surveys (top 30A) and depth profiling survey (top 100A) for the elements, their chemical states, and their relative concentration were analyzed for CIGS thin films. The XPS surface analysis and composition of CIGS thin films were correlated to the bulk composition and Na out-diffusion in the CIGS films from SLG substrates.

  16. Reduction of copper oxides by UV radiation and atomic hydrogen studied by XPS

    NASA Astrophysics Data System (ADS)

    Fleisch, T. H.; Mains, G. J.

    The reduction of polycrystalline cupric oxide (CuO) and cuprous oxide (Cu 2O) by UV irradiation and by atomic hydrogen was investigated with X-ray photoelectron spectroscopy (XPS or ESCA). UV photons from a low pressure mercury lamp(λ=2537A, hv=4.8cV) slowly reduce both CuO and Cu 2O at room temperature. After approximately 10 h of irradiation the sample surfaces appear completely reduced to metallic Cu. This indicates that after that time the top 30 A of the sample pellets, the approximate sampling depth of XPS, have been reduced. Further irradiation causes the reduction to progress through the pellet interior and bulk phase. The sample color changes from dark to metallic copper. Photochemically generated hydrogen atoms reduce copper oxides at ambient temperatures. The reduction rate is about 10 times faster than the one caused by UV light alone. The reduction of Cu 2O is in both cases slightly slower than the one of CuO. The degree of reduction has been calculated from XPS data in different ways involving the atomic ratio of O/Cu, the relative intensity of the shake-up structure of CuO, and changes in the structure of the Cu L 3M 45M 45 Auger line. Freshly reduced Cu surfaces are sensitive to air exposure. They oxidize easily to Cu 2O.

  17. XPS investigation of titanium contact formation to ZnO nanowires.

    PubMed

    Barnett, Chris J; Castaing, Ambroise; Jones, Daniel R; Lewis, Aled R; Jenkins, Lewys J; Cobley, Richard J; Maffeis, Thierry G G

    2017-02-24

    Ti is often used to form an initial Ohmic interface between ZnO and Au due to its low work function, and the TiO2/ZnO heterojunction is also of great importance for many practical applications of nanoparticles. Here, Ti has been controllably deposited onto hydrothermally grown ZnO nanowires and the formation of metal-semiconductor contact has been investigated using x-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and scanning electron microscopy. XPS results showed that that the Ti initially reacts with surface oxygen species to form TiO2, and further deposition results in the formation of oxides with oxidation state numbers lower than four, and eventually metallic Ti on top of the TiO2. The formation of TiC was also observed. XPS showed that the onset of metallic Ti coincided with a Zn 3p core level shift to lower binding energy, indicating upwards band bending and the formation of a rectifying contact. Annealing caused a near-complete conversion of the metallic Ti to TiO2 and caused the Zn 3p to shift back to its original higher binding energy, resulting in downwards band bending and a more Ohmic contact. PL measurements showed that the optical properties of the nanowires are not affected by the contact formation.

  18. Excitation and Ionization in H(1s)-H(1s) Collisions

    SciTech Connect

    Riley, Merle E.; Ritchie, A. Burke

    1999-07-15

    Hydrogen atom - hydrogen atom scattering is a prototype for many of the fundamental principles of atomic collisions. In this work we present an approximation to the H+H system for scattering in the intermediate energy regime of 1 to 100 keV. The approximation ignores electron exchange and two-electron excitation by assuming that one of the atoms is frozen in the 1s state. We allow for the evolution of the active electron by numerically solving the 3D Schroedinger equation. The results capture many features of the problem and are in harmony with recent theoretical studies. Excitation and ionization cross sections are computed and compared to other theory and experiment. New insight into the mechanism of excitation and ionization is inferred from the solutions.

  19. Chandra Spectra of the Cassiopeia A Point Source

    NASA Astrophysics Data System (ADS)

    Stage, Michael D.; Joss, Paul C.

    2001-09-01

    We present the first Chandra High Energy Transmission Grating (HETG) spectra of the X-ray point source (XPS) at the center of the Cassiopeia A supernova remnant, using our recent HETGS observation of Cas A (Obsid 1046), as well as spectra extracted from the long duration archival 50 ksec ACIS-S3 observation (Obsid 114). Discovered in the Chandra first light image, the flux and spectrum of XPS strongly indicate that it is associated with the remnant, but it has been difficult to classify the point source unambiguously. The assertion that the XPS is a weakly magnetized neutron star (B <= 1010 G) radiating primarily via thermal emission is supported by the recent discovery of weak X-ray pulsations with a 13 ms period (H. Tananbaum, talk presented at 198th Mtg. AAS). Such a source is an ideal candidate to fit with our new theoretical atmosphere models (Joss, Madej, and Stage, these proceedings). Early data fit well to a variety of spectral forms, including power laws, model neutron star atmospheres, pure blackbody, and thermal bremsstrahlung (Chakrabarty et al., ApJ 548: 800; Pavlov et al., ApJ 531: L53). With our longer duration and higher resolution observations, we have greater ability to discriminate among the possible spectral models. We have previously carried out model atmosphere fits to a spectrum extracted from the archival 50 ksec observation. Our results yielded effective temperatures (kTeff ~= 0.2 keV) and radii (Reff ~= 2 km) that are comparable to those obtained in earlier fits to neutron-star model atmospheres (Chakrabarty et. al.). The lack of detection of radio pulsations or of a synchrotron nebula from the location of the XPS (McLaughlin et al., ApJ 547: L41) suggests that the XPS is not a classical young pulsar, a result with which we agree. The quality of our model atmosphere fits is superior to those we obtained using simple power law or blackbody models. Furthermore, recent upper limits on the emission from the XPS at near infrared and optical

  20. Operando XPS Characterization of Selective Contacts: The Case of Molybdenum Oxide for Crystalline Silicon Heterojunction Solar Cells

    SciTech Connect

    Ding, Laura; Harvey, Stephen P.; Teeter, Glenn; Bertoni, Mariana I.

    2016-11-21

    We demonstrate the potential of X-ray photoelectron spectroscopy (XPS) to characterize new carrier-selective contacts (CSC) for solar cell application. We show that XPS not only provides information about the surface chemical properties of the CSC material, but that operando XPS, i.e. under light bias condition, can also directly measure the photovoltage that develops at the CSC/absorber interface, revealing device relevant information without the need of assembling a full solar cell. We present the application of the technique to molybdenum oxide hole-selective contact films on a crystalline silicon absorber.

  1. XPS study of Li/Nb ratio in LiNbO3 crystals. Effect of polarity and mechanical processing on LiNbO3 surface chemical composition

    NASA Astrophysics Data System (ADS)

    Skryleva, E. A.; Kubasov, I. V.; Kiryukhantsev-Korneev, Ph. V.; Senatulin, B. R.; Zhukov, R. N.; Zakutailov, K. V.; Malinkovich, M. D.; Parkhomenko, Yu. N.

    2016-12-01

    Different sections of congruent lithium niobate (CLN) crystals have been studied using X-ray photoelectron spectroscopy (XPS). We have developed a method for measuring the lithium-to-niobium atomic ratio Li/Nb from the ratio of the Li1s and Nb4s spectral integral intensities with an overall error of within 8 %. Polarity and mechanical processing affect the Li/Nb ratio on CLN crystal surfaces. The Li/Nb ratio is within the tolerance (0.946 ± 0.074) on the negative cleave surface Z, and there is excess lithium (Li/Nb = 1.25 ± 0.10) on the positive surface. The positive surfaces of the 128° Y cut plates after long exposure to air exhibit LiOH formation indications (obvious lithium excess, higher Li1s spectral binding energy and a wide additional peak in the O1s spectrum produced by nonstructural oxygen). XPS and glow discharge optical electron spectroscopy showed that mechanical processing of differently oriented crystals (X, Z and 128° Y) and different polarities dramatically reduces the Li/Nb ratio. In situ fluorine adsorption experiments revealed the following regularities: fluorine adsorption only occurred on crystal cleaves and was not observed for mechanically processed specimens. Positive cleave surfaces have substantially higher fluorine adsorption capacity compared to negative ones.

  2. Lily Pad Spectra

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The color image on the lower left from the panoramic camera on the Mars Exploration Rover Opportunity shows the 'Lily Pad' bounce-mark area at Meridiani Planum, Mars. This image was acquired on the 3rd sol, or martian day, of Opportunity's mission (Jan.26, 2004). The upper left image is a monochrome (single filter) image from the rover's panoramic camera, showing regions from which spectra were extracted from the 'Lily Pad' area. As noted by the line graph on the right, the green spectra is from the undisturbed surface and the red spectra is from the airbag bounce mark.

  3. A novel computational method for comparing vibrational circular dichroism spectra.

    PubMed

    Shen, Jian; Zhu, Chengyue; Reiling, Stephan; Vaz, Roy

    2010-08-01

    A novel method, SimIR/VCD, for comparing experimental and calculated VCD (vibrational circular dichroism) spectra is developed, based on newly defined spectra similarities. With computationally optimized frequency scaling and shifting, a calculated spectrum can be easily identified to match an observed spectrum, which leads to an unbiased molecular chirality assignment. The time-consuming manual band-fitting work is greatly reduced. With (1S)-(-)-alpha-pinene as an example, it demonstrates that the calculated VCD similarity is correlated with VCD spectra matching quality and has enough sensitivity to identify variations in the spectra. The study also compares spectra calculated using different DFT methods and basis sets. Using this method should facilitate the spectra matching, reduce human error and provide a confidence measure in the chiral assignment using VCD spectroscopy.

  4. Repair and Utilization of the Kratos XSAM 800 X-Ray Photoelectron Spectrometer (XPS)

    NASA Technical Reports Server (NTRS)

    Hampton, Michael D.

    2002-01-01

    The objectives for this summer faculty fellowship were first to repair the Kratos XSAM 800 X-ray Photoelectron Spectrometer (XPS) and then to utilize the instrument to participate in ongoing research projects at KSC and in the researcher's own laboratory at UCF. The first 6 weeks were used in repairing the instrument. Working both alone and with the Kratos service engineer, a number of hardware problems, largely associated with the sample stage control system, were corrected. Defective parts were identified and fixed in the computer driver boards, the stage power supply, and the driver interface. The power supply was completely replaced. After four weeks of work, the instrument was functional. This occurred on a Wednesday. The following Friday the instrument had to be completely shut down because the power to the O & C Building was to be turned off. The instrument was properly secured. On Monday, the instrument was powered up and the original problems returned. After another 2 weeks of work, a software problem was identified. This problem caused the computer to use a defective port for the sample stage control. It was circumvented by rewriting the startup routine. The final 3 weeks of the fellowship were spent using the XPS to analyze samples being studied in the Langley materials project (Martha Williams) and a catalyst project (Dr. Orlando Melendez). During this time, several sample analysis requests from other groups at KSC also came in and those samples were run as well. The summer faculty fellowship also allowed many contacts to be made. After meeting with the sensors group, two projects were identified for collaboration and white papers are being prepared. One project aims to develop small, very sensitive hydrogen detectors and the other to develop a broad area, easily monitored, zero power consumption hydrogen detector. In addition to the work mentioned above, the XPS was utilized in a study underway in Dr. Hampton's laboratory at UCF.

  5. UHV and Ambient Pressure XPS: Potentials for Mg, MgO, and Mg(OH)2 Surface Analysis

    NASA Astrophysics Data System (ADS)

    Head, Ashley R.; Schnadt, Joachim

    2016-12-01

    The surface sensitivity of x-ray photoelectron spectroscopy (XPS) has positioned the technique as a routine analysis tool for chemical and electronic structure information. Samples ranging from ideal model systems to industrial materials can be analyzed. Instrumentational developments in the past two decades have popularized ambient pressure XPS, with pressures in the tens of mbar now commonplace. Here, we briefly review the technique, including a discussion of developments that allow data collection at higher pressures. We illustrate the information XPS can provide by using examples from the literature, including MgO studies. We hope to illustrate the possibilities of ambient pressure XPS to Mg, MgO, and Mg(OH)2 systems, both in fundamental and applied studies.

  6. XPS investigation of thin SiO x and SiO xN y overlayers

    NASA Astrophysics Data System (ADS)

    Birer, Ö.; Sayan, Ş.; Süzer, Ş.; Aydınlı, A.

    1999-05-01

    Angle-resolved XPS is used to determine the thickness and the uniformity of the chemical composition with respect to oxygen and nitrogen of the very thin silicon oxide and oxynitride overlayers grown on silicon.

  7. An investigation of the corrosion of polycrystalline iron by XPS, TMS and CEMS

    NASA Astrophysics Data System (ADS)

    Idczak, K.; Idczak, R.; Konieczny, R.

    2016-06-01

    The room temperature studies of polycrystalline iron exposed to air at various temperatures were performed using: the transmission Mössbauer spectroscopy (TMS), the conversion electron Mössbauer spectroscopy (CEMS) and the X-ray photoelectron spectroscopy (XPS). The unique combination of these techniques allows to determine changes of chemical composition and content of iron oxides simultaneously on the surface region, the 300 nm pre-surface region and the bulk of the samples. The results show that the chemical composition of samples changes significantly and it is strongly dependent on temperature at which the iron sample is exposed to air as well as on investigated region.

  8. Hybridization of XRF/XPS and scatterometry for Cu CMP process control

    NASA Astrophysics Data System (ADS)

    L'Herron, Benoit; Chao, Robin; Kim, Kwanghoon; Lee, Wei Ti; Motoyama, Koichi; Deprospo, Bartlet; Standaert, Theodorus; Gaudiello, John; Goldberg, Cindy

    2015-03-01

    This paper demonstrates the synergy between X-rays techniques and scatterometry, and the benefits to combine the data to improve the accuracy and precision for in-line metrology. Particular example is given to show that the hybridization addresses the challenges of aggressive patterning. In 10nm node back-end-of-line (BEOL) integration, we show that the hybridized data between scatterometry and simultaneous X-Ray Fluorescence (XRF) and X-ray Photoelectron Spectroscopy (XPS) provided the closest dimensional correlation to TEM results compared to the individual technique and CDSEM.

  9. Al2O3 e-Beam Evaporated onto Silicon (100)/SiO2, by XPS

    SciTech Connect

    Madaan, Nitesh; Kanyal, Supriya S.; Jensen, David S.; Vail, Michael A.; Dadson, Andrew; Engelhard, Mark H.; Samha, Hussein; Linford, Matthew R.

    2013-09-25

    We report the XPS characterization of a thin film of Al2O3 (35 nm) deposited via e-beam evaporation onto silicon (100). The film was characterized with monochromatic Al Ka radiation. An XPS survey scan, an Al 2p narrow scan, and the valence band spectrum were collected. The Al2O3 thin film is used as a diffusion barrier layer for templated carbon nanotube (CNT) growth in the preparation of microfabricated thin layer chromatography plates.

  10. A Search for Invisible Decays of the Upsilon(1S)

    SciTech Connect

    Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D.N.; Hooberman, B.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G. /LBL, Berkeley /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, San Diego /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /Harvard U. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa U. /Iowa State U. /Johns Hopkins U. /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT, LNS /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /Mt. Holyoke Coll. /INFN, Naples /Naples U. /INFN, Naples /INFN, Naples /Naples U. /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /Pennsylvania U. /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas U. /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U., IFIC /Victoria U. /Warwick U. /Wisconsin U., Madison

    2009-10-17

    We search for invisible decays of the {Upsilon}(1S) meson using a sample of 91.4 x 10{sup 6} {Upsilon}(3S) mesons collected at the BABAR/PEP-II B Factory. We select events containing the decay {Upsilon}(3S) {yields} {pi}{sup +}{pi}{sup -} {Upsilon}(1S) and search for evidence of an undetectable {Upsilon}(1S) decay recoiling against the dipion system. We set an upper limit on the branching fraction {Beta}({Upsilon}(1S) {yields} invisible) < 3.0 x 10{sup ?4} at the 90% confidence level.

  11. Search for invisible decays of the {upsilon}(1S) resonance

    SciTech Connect

    Rubin, P.; Cawlfield, C.; Eisenstein, B. I.; Karliner, I.; Kim, D.; Lowrey, N.; Naik, P.; Selen, M.; White, E. J.; Wiss, J.; Mitchell, R. E.; Shepherd, M. R.; Besson, D.; Pedlar, T. K.; Cronin-Hennessy, D.; Gao, K. Y.; Hietala, J.; Kubota, Y.; Klein, T.; Lang, B. W.

    2007-02-01

    We present a measurement of the branching fraction of invisible {upsilon}(1S) decays, using 1.2 fb{sup -1} of data collected at the {upsilon}(2S) resonance with the CLEO III detector at CESR. After subtracting expected backgrounds from events that pass selection criteria for invisible {upsilon}(1S) decay in {upsilon}(2S){yields}{pi}{sup +}{pi}{sup -}{upsilon}(1S), we deduce a 90% C.L. upper limit of B[{upsilon}(1S){yields}invisible]<0.39%.

  12. Weak- and hyperfine-interaction-induced 1s2s 1S0 → 1s2 1S0 E1 transition rates of He-like ions

    NASA Astrophysics Data System (ADS)

    Laima, Radžiūtė; Erikas, Gaidamauskas; Gediminas, Gaigalas; Li, Ji-Guang; Dong, Chen-Zhong; Jönsson, Per

    2015-04-01

    Weak- and hyperfine-interaction-induced 1s2s 1S0 → 1s2 1S0 E1 transition rates for the isoelectronic sequence of He-like ions have been calculated using the multi-configuration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction methods. The results should be helpful for the future experimental investigations of parity non-conservation effects. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274254, 11147108, 10979007, U1331122, and U1332206) and in part by the National Basic Research Program of China (Grant No. 2013CB922200).

  13. Functional characterization of the Xcs and Xps type II secretion systems from the plant pathogenic bacterium Xanthomonas campestris pv vesicatoria.

    PubMed

    Szczesny, Robert; Jordan, Matthias; Schramm, Claudia; Schulz, Steve; Cogez, Virginie; Bonas, Ulla; Büttner, Daniela

    2010-09-01

    *Type II secretion (T2S) systems of many plant-pathogenic bacteria often secrete cell wall-degrading enzymes into the plant apoplast. *Here, we show that the Xps-T2S system from the plant pathogen Xanthomonas campestris pv vesicatoria (Xcv) promotes disease and contributes to the translocation of effector proteins that are delivered into the plant cell by the type III secretion (T3S) system. *The Xcs-T2S system instead lacks an obvious virulence function. However, individual xcs genes can partially complement mutants in homologous xps genes, indicating that they encode functional components of T2S systems. Enzyme activity assays showed that the Xps system contributes to secretion of proteases and xylanases. We identified the virulence-associated xylanase XynC as a substrate of the Xps system. However, homologs of known T2S substrates from other Xanthomonas spp. are not secreted by the T2S systems from Xcv. Thus, T2S systems from Xanthomonas spp. appear to differ significantly in their substrate specificities. *Transcript analyses revealed that expression of xps genes in Xcv is activated by HrpG and HrpX, key regulators of the T3S system. By contrast, expression of xynC and extracellular protease and xylanase activities are repressed by HrpG and HrpX, suggesting that components and substrates of the Xps system are differentially regulated.

  14. In situ XPS study of Pd(1 1 1) oxidation. Part 1: 2D oxide formation in 10 -3 mbar O 2

    NASA Astrophysics Data System (ADS)

    Zemlyanov, Dmitry; Aszalos-Kiss, Balazs; Kleimenov, Evgueni; Teschner, Detre; Zafeiratos, Spiros; Hävecker, Michael; Knop-Gericke, Axel; Schlögl, Robert; Gabasch, Harald; Unterberger, Werner; Hayek, Konrad; Klötzer, Bernhard

    2006-03-01

    The oxidation of the Pd(1 1 1) surface was studied by in situ XPS during heating and cooling in 3 × 10 -3 mbar O 2. A number of adsorbed/dissolved oxygen species were identified by in situ XPS, such as the two dimensional surface oxide (Pd 5O 4), the supersaturated O ads layer, dissolved oxygen and the (√{67}×√{67})R 12.2° surface structure. Exposure of the Pd(1 1 1) single crystal to 3 × 10 -3 mbar O 2 at 425 K led to formation of the 2D oxide phase, which was in equilibrium with a supersaturated O ads layer. The supersaturated O ads layer was characterized by the O 1s core level peak at 530.37 eV. The 2D oxide, Pd 5O 4, was characterized by two O 1s components at 528.92 eV and 529.52 eV and by two oxygen-induced Pd 3d 5/2 components at 335.5 eV and 336.24 eV. During heating in 3 × 10 -3 mbar O 2 the supersaturated O ads layer disappeared whereas the fraction of the surface covered with the 2D oxide grew. The surface was completely covered with the 2D oxide between 600 K and 655 K. Depth profiling by photon energy variation confirmed the surface nature of the 2D oxide. The 2D oxide decomposed completely above 717 K. Diffusion of oxygen in the palladium bulk occurred at these temperatures. A substantial oxygen signal assigned to the dissolved species was detected even at 923 K. The dissolved oxygen was characterised by the O 1s core level peak at 528.98 eV. The "bulk" nature of the dissolved oxygen species was verified by depth profiling. During cooling in 3 × 10 -3 mbar O 2, the oxidised Pd 2+ species appeared at 788 K whereas the 2D oxide decomposed at 717 K during heating. The surface oxidised states exhibited an inverse hysteresis. The oxidised palladium state observed during cooling was assigned to a new oxide phase, probably the (√{67}×√{67})R 12.2° structure.

  15. XPS and SIMS study of the surface and interface of aged C+ implanted uranium

    SciTech Connect

    Donald, Scott B.; Siekhaus, Wigbert J.; Nelson, Art J.

    2016-09-08

    X-ray photoelectron spectroscopy in combination with secondary ion mass spectrometry depth profiling were used to investigate the surface and interfacial chemistry of C+ ion implanted polycrystalline uranium subsequently oxidized in air for over 10 years at ambient temperature. The original implantation of 33 keV C+ ions into U238 with a dose of 4.3 × 1017 cm–3 produced a physically and chemically modified surface layer that was characterized and shown to initially prevent air oxidation and corrosion of the uranium after 1 year in air at ambient temperature. The aging of the surface and interfacial layers were examined by using the chemical shift of the U 4f, C 1s, and O 1s photoelectron lines. In addition, valence band spectra were used to explore the electronic structure of the aged carbide surface and interface layer. Moreover, the time-of-flight secondary ion mass spectrometry depth profiling results for the aged sample confirmed an oxidized uranium carbide layer over the carbide layer/U metal interface.

  16. Si XII X-ray Satellite Lines in Solar Flare Spectra

    NASA Technical Reports Server (NTRS)

    Phillips, K. J. H.; Dubau, J.; Sylwester, J.; Sylwester, B.

    2006-01-01

    The temperature dependence of the Si XII n=3 and n=4 dielectronic satellite line features at 5.82A and 5.56A respectively, near the Si XIII 1s(sup 2)-1s3p and 1s(sup 2)-1s4p lines (5.681A and 5.405A), is calculated using atomic data presented here. The resulting theoretical spectra are compared with solar flare spectra observed by the RESIK spectrometer on the CORONAS-F spacecraft. The satellites, like the more familiar n=2 satellites near the Si XIII 1s(sup 2)-1s2p lines, are formed mostly by dielectronic recombination, but unlike the n=2 satellites are unblended. The implications for similar satellite lines in flare Fe spectra are discussed.

  17. Soil wettability can be explained by the chemical composition of particle interfaces - An XPS study

    PubMed Central

    Woche, Susanne K.; Goebel, Marc-O.; Mikutta, Robert; Schurig, Christian; Kaestner, Matthias; Guggenberger, Georg; Bachmann, Jörg

    2017-01-01

    Soil wettability (quantified in terms of contact angle, CA) is crucial for physical, chemical, and biological soil functioning. As the CA is determined by components present within the outmost nanometer of particles, this study applied X-ray photoelectron spectroscopy (XPS) with a maximum analysis depth of 10 nm to test the relationship between CA and surface elemental composition, using soil samples from a chronosequence where CA increased from 0° (0 yrs) to about 98° (120 yrs). Concurrently, as seen by XPS, C and N content increased and the content of O and the mineral-derived cations (Si, Al, K, Na, Ca, Mg, Fe) decreased. The C content was positively correlated with CA and least squares fitting indicated increasing amounts of non-polar C species with soil age. The contents of O and the mineral-derived cations were negatively correlated with CA, suggesting an increasing organic coating of the minerals that progressively masked the underlying mineral phase. The atomic O/C ratio was found to show a close negative relationship with CA, which applied as well to further sample sets of different texture and origin. This suggests the surface O/C ratio to be a general parameter linking surface wettability and surface elemental composition. PMID:28211469

  18. Surface composition XPS analysis of a plasma treated polystyrene: Evolution over long storage periods.

    PubMed

    Ba, Ousmane M; Marmey, Pascal; Anselme, Karine; Duncan, Anthony C; Ponche, Arnaud

    2016-09-01

    A polystyrene surface (PS) was initially treated by cold nitrogen and oxygen plasma in order to incorporate in particular amine and hydroxyl functions, respectively. The evolution of the chemical nature of the surface was further monitored over a long time period (580 days) by chemical assay, XPS and contact angle measurements. Surface density quantification of primary amine groups was performed using three chemical amine assays: 4-nitrobenzaldehyde (4-NBZ), Sulfo succinimidyl 6-[3'(2 pyridyldithio)-pionamido] hexanoate (Sulfo-LC-SPDP) and iminothiolane (ITL). The results showed amine densities were in the range of 2 per square nanometer (comparable to the results described in the literature) after 5min of nitrogen plasma treatment. Over the time period investigated, chemical assays, XPS and contact angles suggest a drastic significant evolution of the chemical nature of the surface within the first two weeks. Beyond that time period and up to almost two years, nitrogen plasma modified substrates exhibits a slow and continuous oxidation whereas oxygen plasma modifed polystyrene surface is chemically stable after two weeks of storage. The latter appeared to "ease of" showing relatively mild changes within the one year period. Our results suggest that it may be preferable to wait for a chemical "stabilization" period of two weeks before subsequent covalent immobilization of proteins onto the surface. The originality of this work resides in the study of the plasma treated surface chemistry evolution over long periods of storage time (580 days) considerably exceeding those described in the literature.

  19. An XPS study for mechanisms of arsenate adsorption onto a magnetite-doped activated carbon fiber.

    PubMed

    Zhang, Shujuan; Li, Xiao-yan; Chen, J Paul

    2010-03-01

    The surface and bulk structures of a newly developed carbon-based iron-containing adsorbent for As(V) adsorption were investigated by using X-ray diffraction (XRD), field emission scanning electronic microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS). XRD patterns of the adsorbents indicated that the modified activated carbon fiber (MACF) was a simple mixture of the raw activated carbon fiber (RACF) and magnetite. After modification, a porous film was formed on the surface of the MACF with nano-sized magnetite on it. The As(V) uptake on the MACF was highly pH dependent and was facilitated in acidic solutions. XPS studies demonstrated that the surface oxygen-containing functional groups were involved in the adsorption and that magnetite played a key role in As(V) uptake. The dominance of HAsO(4)(2-) in surface complexes and the pH effect on As(V) uptake demonstrated that the monoprotonated bidentate complexes were dominant on the surface of the MACF. No reduction of As(V) was observed on the surface of the ACFs.

  20. An XPS analytical approach for elucidating the microbially mediated enargite oxidative dissolution.

    PubMed

    Fantauzzi, M; Rossi, G; Elsener, B; Loi, G; Atzei, D; Rossi, A

    2009-04-01

    In this work, the microbe-mediated oxidative dissolution of enargite surfaces (Cu(3)AsS(4)) was studied on powdered samples exposed to 9K nutrient solution (pH 2.3) inoculated by Acidithiobacillus ferrooxidans initially adapted to arsenopyrite. These conditions simulate the acid mine environment. The redox potential of the inoculated solutions increased up to +0.72 V vs normal hydrogen electrode (NHE), indicating the increase of the Fe(3+) to Fe(2+) ratio, and correspondingly the pH decreased to values as low as 1.9. In the sterile 9K control, the redox potential and pH remained constant at +0.52 V NHE and 2.34, respectively. Solution analyses showed that in inoculated medium Cu and As dissolved stoichiometrically with a dissolution rate of about three to five times higher compared to the sterile control. For the first time, X-ray photoelectron spectroscopy (XPS) was carried out on the bioleached enargite powder with the aim of clarifying the role of the microorganisms in the dissolution process. XPS results provide evidence of the formation of a thin oxidized layer on the mineral surface. Nitrogen was also detected on the bioleached surfaces and was attributed to the presence of an extracellular polymer substance layer supporting a mechanism of bacteria attachment via the formation of a biofilm a few nanometers thick, commonly known as nanobiofilm.

  1. Behavior of Supported Palladium Oxide Nanoparticles under Reaction Conditions, Studied with near Ambient Pressure XPS.

    PubMed

    Jürgensen, Astrid; Heutz, Niels; Raschke, Hannes; Merz, Klaus; Hergenröder, Roland

    2015-08-04

    Near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) is a promising method to close the "pressure gap", and thus, study the surface composition during heterogeneous reactions in situ. The specialized spectrometers necessary for this analytical technique have recently been adapted to operate with a conventional X-ray source, making it available for routine quantitative analysis in the laboratory. This is shown in the present in situ study of the partial oxidation of 2-propanol catalyzed with PdO nanoparticles supported on TiO2, which was investigated under reaction conditions as a function of gas composition (alcohol-to-oxygen ratio) and temperature. Exposure of the nanoparticles to 2-propanol at 30 °C leads to immediate partial reduction of the PdO, followed by a continuous reduction of the remaining PdO during heating. However, gaseous oxygen inhibits the reduction of PdO below 90 °C, and the oxidation of 2-propanol to carboxylates only occurs in the presence of oxygen above 90 °C. These results support the theory that metallic palladium is the active catalyst material, and they show that environmental conditions affect the nanoparticles and the reaction process significantly. The study also revealed challenges and limitations of this analytical method. Specifically, the intensity and fixed photon energy of a conventional X-ray source limit the spectral resolution and surface sensitivity of lab-based NAP-XPS, which affect precision and accuracy of the quantitative analysis.

  2. Quantification problems in depth profiling of pwr steels using Ar+ ion sputtering and XPS analysis.

    PubMed

    Ignatova, Velislava A; Van Den Berghe, Sven; Van Dyck, Steven; Popok, Vladimir N

    2006-10-01

    The oxide scales of AISI 304 formed in boric acid solutions at 300 degrees C and pH = 4.5 have been studied using X-ray photoelectron spectroscopy (XPS) depth profiling. The present focus is depth profile quantification both in depth and chemical composition on a molecular level. The roughness of the samples is studied by atomic force microscopy before and after sputtering, and the erosion rate is determined by measuring the crater depth with a surface profilometer and vertical scanning interferometry. The resulting roughness (20-30 nm), being an order of magnitude lower than the crater depth (0.2-0.5 microm), allows layer-by-layer profiling, although the ion-induced effects result in an uncertainty of the depth calibration of a factor of 2. The XPS spectrum deconvolution and data evaluation applying target factor analysis allows chemical speciation on a molecular level. The elemental distribution as a function of the sputtering time is obtained, and the formation of two layers is observed-one hydroxide (mainly iron-nickel based) on top and a second one deeper, mainly consisting of iron-chromium oxides.

  3. The composition of polymer composite fracture surfaces as studied by XPS

    SciTech Connect

    Wiegand, D.A.; Pinto, J.J.

    1996-12-01

    The composition of the fracture surfaces of a composite made up of a polycrystalline organic nonpolymeric filler and a binder composed of a copolymer was studied by XPS. Because the binder and the filler of the composite each have at least one element not in common it is possible to easily distinguish between the binder and filler by XPS. A measure of the relative amounts of binder and filler on the fracture surfaces, therefore, could be made as a function of the sample temperature, T, and the strain rate during fracture. The ratio of filler to binder, F/B, increases with decreasing T at constant strain rate and is least sensitive to strain rate at T`s below T{sub G}, the quasi static glass transition T. At higher T, F/B increases with strain rate at constant T. These results indicate that as the binder becomes stronger and stiffer due to a decrease in T or an increase in strain rate more of the fracture processes take place in the filler whose properties are expected to be less sensitive to T and strain rate. These results are related to the fracture properties as observed by uniaxial compression.

  4. Soil wettability can be explained by the chemical composition of particle interfaces - An XPS study

    NASA Astrophysics Data System (ADS)

    Woche, Susanne K.; Goebel, Marc-O.; Mikutta, Robert; Schurig, Christian; Kaestner, Matthias; Guggenberger, Georg; Bachmann, Jörg

    2017-02-01

    Soil wettability (quantified in terms of contact angle, CA) is crucial for physical, chemical, and biological soil functioning. As the CA is determined by components present within the outmost nanometer of particles, this study applied X-ray photoelectron spectroscopy (XPS) with a maximum analysis depth of 10 nm to test the relationship between CA and surface elemental composition, using soil samples from a chronosequence where CA increased from 0° (0 yrs) to about 98° (120 yrs). Concurrently, as seen by XPS, C and N content increased and the content of O and the mineral-derived cations (Si, Al, K, Na, Ca, Mg, Fe) decreased. The C content was positively correlated with CA and least squares fitting indicated increasing amounts of non-polar C species with soil age. The contents of O and the mineral-derived cations were negatively correlated with CA, suggesting an increasing organic coating of the minerals that progressively masked the underlying mineral phase. The atomic O/C ratio was found to show a close negative relationship with CA, which applied as well to further sample sets of different texture and origin. This suggests the surface O/C ratio to be a general parameter linking surface wettability and surface elemental composition.

  5. On the 1s24d Fine Structures of B III and Ne VIII

    NASA Astrophysics Data System (ADS)

    Wang, Zhiwen; Z, W. Wang; Kwong, T. Chung; Zhu, Xiaowei

    1995-01-01

    The fine structure of lithium-like 1s24d states in the literature behaves irregularly as a function of Z. The fine structures of the B III and Ne VIII fall well below the isoelectronic curve. The term energies of these two systems in the data tables also give worse agreement with the theoretical prediction. In this work, we show that the reason for this unusual situation is caused by a misidentification in the original spectra. When the correct identifications are made, the fine structures of both systems fall on the isoelectronic curve and the agreement between theory and experiment is excellent.

  6. As-Received, Ozone Cleaned and Ar+ Sputtered Surfaces of Hafnium Oxide Grown by Atomic Layer Deposition and Studied by XPS

    SciTech Connect

    Engelhard, Mark H.; Herman, Jacob A.; Wallace, Robert; Baer, Donald R.

    2012-06-27

    In this study, X-ray photoelectron spectroscopy (XPS) characterization was performed on 47 nm thick hafnium oxide (HfO{sub 2}) films grown by atomic layer deposition using TEMA-Hf/H{sub 2}O at 250 C substrate temperature. HfO{sub 2} is currently being studied as a possible replacement for Silicon Oxide (SiO{sub 2}) as a gate dielectric in electronics transistors. XPS spectra were collected on a Physical Electronics Quantum 2000 Scanning ESCA Microprobe using a monochromatic Al K{sub a} X-ray (1486.7 eV) excitation source. The sample was analyzed under the following conditions: as received, after UV irradiation for five minutes, and after sputter cleaning with 2 kV Ar{sup +} ions for 180 seconds. Survey scans showed carbon, oxygen, and hafnium as the major species in the film, while the only minor species of argon and carbide was detected after sputtering. Adventitious carbon initially composed approximately 18.6 AT% of the surface, but after UV cleaning it was reduced to 2.4 AT%. This demonstrated that that the majority of carbon was due to adventitious carbon. However, after 2 kV Ar{sup +} sputtering there was still only trace amounts of carbon at {approx}1 AT%, Some of this trace carbon is now in the form of a carbide due to the interaction with Ar{sup +} used for sputter cleaning. Furthermore, the stoiciometric ratio of oxygen and hafnium is consistent with a high quality HfO{sub 2} film.

  7. Spectra of Surface Waves

    DTIC Science & Technology

    1989-03-22

    with a wave follower during Marsen. J. Gophysical Res. 88, 9844-9849. 11. Hughes, B.A., 1978. The effects on internal waves on surface waves : 2...Spectra of Surface Waves K. Watson March 1989 JSR-88-130 Approved for public release; distribution unlimited. DTIC SELECTE JUN0 11989 0 JASONE The...Arlington, VA 22209 8503Z 11. TITLE (hlde Secvfty Cof.kaftn) SPECTRA OF SURFACE WAVES (U) 12. PERSONAL AUTHOfRS) K. Watson 13a. TYPE OF REPORT 13b. TIME

  8. Temperature-dependent electronic and vibrational structure of the 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide room-temperature ionic liquid surface: a study with XPS, UPS, MIES, and HREELS.

    PubMed

    Krischok, S; Eremtchenko, M; Himmerlich, M; Lorenz, P; Uhlig, J; Neumann, A; Ottking, R; Beenken, W J D; Höfft, O; Bahr, S; Kempter, V; Schaefer, J A

    2007-05-10

    The near-surface structure of the room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide has been investigated as a function of temperature between 100 and 620 K. We used a combination of photoelectron spectroscopies (XPS and UPS), metastable induced electron spectroscopy (MIES), and high-resolution electron energy loss spectroscopy (HREELS). The valence band and HREELS spectra are interpreted on the basis of density functional theory (DFT) calculations. At room temperature, the most pronounced structures in the HREELS, UPS, and MIES spectra are related to the CF3 group in the anion. Spectral changes observed at 100 K are interpreted as a change of the molecular orientation at the outermost surface, when the temperature is lowered. At elevated temperatures, early volatilization, starting at 350 K, is observed under reduced pressure.

  9. Quantum spectra and dynamics

    NASA Astrophysics Data System (ADS)

    Arce, Julio Cesar

    This work focuses on time-dependent quantum theory and methods for the study of the spectra and dynamics of atomic and molecular systems. Specifically, we have addressed the following two problems: (1) Development of a time-dependent spectral method for the construction of spectra of simple quantum systems. This includes the calculation of eigenenergies, the construction of bound and continuum eigenfunctions, and the calculation of photo cross-sections. Computational applications include the quadrupole photoabsorption spectra and dissociation cross-sections of molecular hydrogen from various vibrational states in its ground electronic potential-energy curve. This method is seen to provide an advantageous alternative, both from the computational and conceptual point of view, to existing standard methods. (2) Explicit time-dependent formulation of photoabsorption processes -- Analytical solutions of the time-dependent Schrodinger equation are constructed and employed for the calculation of probability densities, momentum distributions, fluxes, transition rates, expectation values and correlation functions. These quantities are seen to establish the link between the dynamics and the calculated, or measured, spectra and cross-sections, and to clarify the dynamical nature of the excitation, transition and ejection processes. Numerical calculations on atomic and molecular hydrogen corroborate and complement the previous results, allowing the identification of different regimes during the photoabsorption process.

  10. Quantum Spectra and Dynamics

    NASA Astrophysics Data System (ADS)

    Arce, Julio Cesar

    1992-01-01

    This work focuses on time-dependent quantum theory and methods for the study of the spectra and dynamics of atomic and molecular systems. Specifically, we have addressed the following two problems: (i) Development of a time-dependent spectral method for the construction of spectra of simple quantum systems--This includes the calculation of eigenenergies, the construction of bound and continuum eigenfunctions, and the calculation of photo cross-sections. Computational applications include the quadrupole photoabsorption spectra and dissociation cross-sections of molecular hydrogen from various vibrational states in its ground electronic potential -energy curve. This method is seen to provide an advantageous alternative, both from the computational and conceptual point of view, to existing standard methods. (ii) Explicit time-dependent formulation of photoabsorption processes --Analytical solutions of the time-dependent Schrodinger equation are constructed and employed for the calculation of probability densities, momentum distributions, fluxes, transition rates, expectation values and correlation functions. These quantities are seen to establish the link between the dynamics and the calculated, or measured, spectra and cross-sections, and to clarify the dynamical nature of the excitation, transition and ejection processes. Numerical calculations on atomic and molecular hydrogen corroborate and complement the previous results, allowing the identification of different regimes during the photoabsorption process.

  11. Atomic Spectra Database (ASD)

    National Institute of Standards and Technology Data Gateway

    SRD 78 NIST Atomic Spectra Database (ASD) (Web, free access)   This database provides access and search capability for NIST critically evaluated data on atomic energy levels, wavelengths, and transition probabilities that are reasonably up-to-date. The NIST Atomic Spectroscopy Data Center has carried out these critical compilations.

  12. An XPS study on the impact of relative humidity on the aging of UO2 powders

    NASA Astrophysics Data System (ADS)

    Donald, Scott B.; Dai, Zurong R.; Davisson, M. Lee; Jeffries, Jason R.; Nelson, Art J.

    2017-04-01

    High resolution x-ray photoemission spectroscopy (XPS) was used to characterize the chemical speciation of high purity uranium dioxide (UO2) powder samples following aging for periods of up to one year under controlled conditions with relative humidity ranging from 34% to 98%. A systematic shift to higher uranium oxidation states, and thus an increase in the mean uranium valence, was found to directly correlate with the dose of water received (i.e. the product of exposure time and relative humidity). Exposure duration was found to have a greater impact on sample aging than relative humidity. The sample aged at 98% relative humidity was found to have unique structural differences for exposure time beyond 180 days when observed by scanning electron microscopy (SEM).

  13. XPS and NMR analysis on 12CaO•7Al2O3

    NASA Astrophysics Data System (ADS)

    Pan, R. K.; Feng, S.; Tao, H. Z.

    2017-01-01

    12CaO·7Al2O3 (C12A7) glass was prepared by the melt quenching method. The glass transition temperature (T g) and the crystallization temperature (T c) of C12A7 glass are about 1050 K and 1194 K, respectively, measured by the differential scanning calorimetry (DSC). The structure of C12A7 glass was investigated by X-ray photoelectron spectroscopy (XPS) as well as magic angle spinning-nuclear magnetic resonance spectroscopy (MAS-NMR). Analysis shows that Al coordination number is about four in C12A7 glass, in which AlO4 tetrahedrons and bridging oxygens (BO) constitute the glass network. Ca2+ produces a few of non-bridging oxygens (NBO), which become neighbours of Al.

  14. XPS and XAS studies of copper(II) sorbed onto a synthetic pyrite surface.

    PubMed

    Naveau, Aude; Monteil-Rivera, Fanny; Guillon, Emmanuel; Dumonceau, Jacques

    2006-11-01

    Compounds containing copper are likely candidates to delay iodide migration in environmental media through the formation of sparingly soluble phases. Preliminary experiments showed that iodide was neither sorbed onto chalcopyrite nor by a binary system pyrite/copper(II), although significant amounts of copper were present at the pyrite surface. In the present study, spectroscopic studies (XPS, XANES and EXAFS) were thus performed to determine the nature of sorbed copper species. Although introduced as Cu(II), copper was mainly present at the oxidation state (I) on the pyrite surface suggesting a heterogeneous reduction process. Moreover, copper appeared tetrahedrally coordinated to two sulfur and two oxygen atoms onto the pyrite surface, a chemical environment, which seemingly stabilized the metal and made it unreactive towards iodide.

  15. FTIR, EPMA, Auger, and XPS analysis of impurity precipitates in CdS films

    SciTech Connect

    Webb, J.D.; Rose, D.H.; Niles, D.W.; Swartzlander, A.; Al-Jassim, M.M.

    1997-12-31

    Impurities in cadmium sulfide (CdS) films are a concern in the fabrication of copper (indium, gallium) diselenide (CIGS) and cadmium telluride (CdTe) photovoltaic devices. Films of CdS grown using chemical bath deposition (CBD) generally yield better devices than purer CdS films grown using vacuum deposition techniques, despite the higher impurity concentrations typically observed in the CBD CdS films. In this work, the authors present Fourier transform infrared (FTIR), Auger, electron microprobe (EPMA), X-ray photoelectron spectroscopic (XPS), and secondary ion mass spectroscopic (SIMS) analyses of the impurities in CBD CdS films, and show that these differ as a function of substrate type and film deposition conditions. They also show that some of these impurities exist as 10{sup 2} micron-scale precipitates.

  16. Spectral studies on sulfur poisoning of Pd/Mg6Ni by NEXAFS and XPS

    NASA Astrophysics Data System (ADS)

    Yagi, S.; Nambu, M.; Tsukada, C.; Ogawa, S.; Kutluk, G.; Namatame, H.; Taniguchi, M.

    2013-02-01

    We have studied on the hydrogen storage materials based on Mg-Ni alloy and fabricated the sample constructed with the Pd thin layer (TL) on Mg6Ni alloy substrate. The adsorption behavior of the dimethyl disulfide (DMS) molecules on the sample has been measured to reveal the sulfur poisoning of the Pd TL/Mg6Ni by means of XPS and Sulfur K-edge NEXAFS techniques. The chemisorbed DMS, methanethiolate (MT) and atomic S have been observed on the surface. Especially, it is clear that some atomic S has been oxidized by air and detected the adsorbate of the SO32- and SO42- species. During exposure to the atmosphere, most of the adsorbed DMS and MT adsorbates desorb from the Pd TL surface. We thus conclude the Pd TL might be able to prevent the hydrogen storage materials from the sulfur poisoning.

  17. Interfacial analysis of tribological systems containing molybdenum disulfide and iron using XPS and CEMS

    NASA Technical Reports Server (NTRS)

    Zabinski, J. S.; George, T.; Tatarchuk, B. J.

    1989-01-01

    In the present evaluation of results from studies of the interfacial chemistry and morphology of a buried lubricant-substrate interface, specimens of increasing complexity that culminated with the effects of excess sulfur and defects were characterized by XPS and SEM, as well as conversion-electron Moessbauer spectroscopy (CEMS). In order to simulate sputtered systems, single crystals of MoS2 were damaged with Ar(+) bombardment and coated with Fe. Fe is found to react differently with MoS2 depending on surface treatments, surface defects, annealing treatments, and the presence of excess sulfur. The annealing temperature determines which compounds are formed, as well as the crystal habit and plane at the Fe-MoS2 interface.

  18. Initial oxidation behaviors of nitride surfaces of uranium by XPS analysis

    NASA Astrophysics Data System (ADS)

    Liu, Kezhao; Luo, Lizu; Luo, Lili; Long, Zhong; Hong, Zhanglian; Yang, Hui; Wu, Sheng

    2013-09-01

    The nitride surfaces of uranium were prepared by the surface glow plasma nitriding (SGPN) and plasma immersion ion implantation (PIII) methods. The initial oxidation behaviors of modified surfaces were studied by X-ray photoelectron spectroscopy (XPS). The SGPN on the uranium surface led to a single layer of uranium sesquinitride (U2N3), while the PIII on the surface resulted in a compound layer composed of U2N3 and uranium dioxide (UO2). The oxygen covered on these modified layers led to the formation of UO2 from U2N3 and U2N3 from UN. The oxidized nitrogen species were also observed on the two types of nitriding layers, with the discussion of the N-O coaction behaviors.

  19. XPS analysis of lithium surface and modification of surface state for uniform deposition of lithium

    SciTech Connect

    Kanamura, K.; Shiraishi, S.; Takehara, Z.

    1995-12-31

    The surface modification of lithium deposited at various current densities in propylene carbonate containing 1.0 ml dm{sup {minus}3} LiClO{sub 4} was performed by addition of various amounts of HF into the electrolyte, in order to investigate the effect of the HF addition on the surface reaction of lithium. XPS and SEM analyses showed that the surface state of lithium was influenced by the concentration of HF and the electrodeposition current. These two parameters are related to the chemical reaction rate of the lithium surface with HF and the electrodeposition rate of lithium, respectively. The surface modification was highly effective in suppressing lithium dendrite formation when the chemical reaction rate with HF was greater than the electrochemical deposition rate of lithium.

  20. XPS study of PBO fiber surface modified by incorporation of hydroxyl polar groups in main chains

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Hu, Dayong; Jin, Junhong; Yang, Shenglin; Li, Guang; Jiang, Jianming

    2010-01-01

    Dihydroxy poly(p-phenylene benzobisoxazole) (DHPBO), a modified poly(p-phenylene benzoxazole) (PBO) polymer containing double hydroxyl groups in polymer chains, was synthesized by copolymerization of 4,6-diamino resorcinol dihydrochloride (DAR), purified terephthalic acid (TA) and 2,5-dihydroxyterephthalic acid (DHTA). DHPBO fibers were prepared by dry-jet wet-spinning method. The effects of hydroxyl polar groups on the surface elemental compositions of PBO fiber were investigated by X-ray photoelectron spectroscopy (XPS). The results show that the ratio of oxygen/carbon on the surface of DHPBO fibers is higher than that on the surface of PBO fibers, which indicates the content of polar groups on the surface of DHPBO fiber increase compared with PBO fiber.

  1. An XPS study on the impact of relative humidity on the aging of UO2 powders

    DOE PAGES

    Donald, Scott B.; Dai, Zurong R.; Davisson, M. Lee; ...

    2017-02-10

    High resolution x-ray photoemission spectroscopy (XPS) was used to characterize the chemical speciation of high purity uranium dioxide (UO2) powder samples following aging for periods of up to one year under controlled conditions with relative humidity ranging from 34% to 98%. A systematic shift to higher uranium oxidation states, and thus an increase in the mean uranium valence, was found to directly correlate with the dose of water received (i.e. the product of exposure time and relative humidity). Exposure duration was found to have a greater impact on sample aging than relative humidity. Lastly, the sample aged at 98% relativemore » humidity was found to have unique structural differences for exposure time beyond 180 days when observed by scanning electron microscopy (SEM).« less

  2. Study of gadolinia-doped ceria solid electrolyte surface by XPS

    SciTech Connect

    Datta, Pradyot Majewski, Peter; Aldinger, Fritz

    2009-02-15

    Gadolinia-doped ceria (CGO) is an important material to be used as electrolyte for solid oxide fuel cell for intermediate temperature operation. Ceria doped with 10 mol% gadolinia (Ce{sub 0.9}Gd{sub 0.1}O{sub 1.95}) was prepared by conventional solid state synthesis and found to be single phase by room temperature X-ray diffraction (XRD). The chemical states of the surface of the prepared sample were analyzed by X-ray photoelectron spectroscopy (XPS). Though Gd was present in its characteristic chemical state, Ce was found in both Ce{sup 4+} and Ce{sup 3+} states. Presence of Ce{sup 3+} state was ascribed to the differential yield of oxygen atoms in the sputtering process.

  3. Arsenopyrite and pyrite bioleaching: evidence from XPS, XRD and ICP techniques.

    PubMed

    Fantauzzi, Marzia; Licheri, Cristina; Atzei, Davide; Loi, Giovanni; Elsener, Bernhard; Rossi, Giovanni; Rossi, Antonella

    2011-10-01

    In this work, a multi-technical bulk and surface analytical approach was used to investigate the bioleaching of a pyrite and arsenopyrite flotation concentrate with a mixed microflora mainly consisting of Acidithiobacillus ferrooxidans. X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and X-ray-induced Auger electron spectroscopy mineral surfaces investigations, along with inductively coupled plasma-atomic emission spectroscopy and carbon, hydrogen, nitrogen and sulphur determination (CHNS) analyses, were carried out prior and after bioleaching. The flotation concentrate was a mixture of pyrite (FeS(2)) and arsenopyrite (FeAsS); after bioleaching, 95% of the initial content of pyrite and 85% of arsenopyrite were dissolved. The chemical state of the main elements (Fe, As and S) at the surface of the bioreactor feed particles and of the residue after bioleaching was investigated by X-ray photoelectron and X-ray excited Auger electron spectroscopy. After bioleaching, no signals of iron, arsenic and sulphur originating from pyrite and arsenopyrite were detected, confirming a strong oxidation and the dissolution of the particles. On the surfaces of the mineral residue particles, elemental sulphur as reaction intermediate of the leaching process and precipitated secondary phases (Fe-OOH and jarosite), together with adsorbed arsenates, was detected. Evidence of microbial cells adhesion at mineral surfaces was also produced: carbon and nitrogen were revealed by CHNS, and nitrogen was also detected on the bioleached surfaces by XPS. This was attributed to the deposition, on the mineral surfaces, of the remnants of a bio-film consisting of an extra-cellular polymer layer that had favoured the bacterial action.

  4. A comparison of methods for calculating O(1S) lifetimes

    NASA Astrophysics Data System (ADS)

    Burns, G. B.; Reid, J. S.

    It is shown theoretically and with simulated data that O(1S) lifetimes determined by the cross-spectral method (Paulson and Shepherd, 1965) are significant overestimates. A comparison is made of the cross-spectral and impulse function analysis (Burns and Reid, 1984) methods using photometric data collected at Macquarie Island (54.5 deg S, 159.0 deg E geographic). The results support the view that the O(1S) state is excited predominantly by an indirect process.

  5. A comparative theoretical study on core-hole excitation spectra of azafullerene and its derivatives

    SciTech Connect

    Deng, Yunfeng; Gao, Bin; Deng, Mingsen; Luo, Yi

    2014-03-28

    The core-hole excitation spectra—near-edge x-ray absorption spectroscopy (NEXAFS), x-ray emission spectroscopy (XES), and x-ray photoelectron spectroscopy (XPS) shake-up satellites have been simulated at the level of density functional theory for the azafullerene C{sub 59}N and its derivatives (C{sub 59}N){sup +}, C{sub 59}HN, (C{sub 59}N){sub 2}, and C{sub 59}N–C{sub 60}, in which the XPS shake-up satellites were simulated using our developed equivalent core hole Kohn-Sham (ECH-KS) density functional theory approach [B. Gao, Z. Wu, and Y. Luo, J. Chem. Phys. 128, 234704 (2008)] which aims for the study of XPS shake-up satellites of large-scale molecules. Our calculated spectra are generally in good agreement with available experimental results that validates the use of the ECH-KS method in the present work. The nitrogen K-edge NEXAFS, XES, and XPS shake-up satellites spectra in general can be used as fingerprints to distinguish the azafullerene C{sub 59}N and its different derivatives. Meanwhile, different carbon K-edge spectra could also provide detailed information of (local) electronic structures of different molecules. In particular, a peak (at around 284.5 eV) in the carbon K-edge NEXAFS spectrum of the heterodimer C{sub 59}N–C{sub 60} is confirmed to be related to the electron transfer from the C{sub 59}N part to the C{sub 60} part in this charge-transfer complex.

  6. The influence of surface chemistry on GSR particles: using XPS to complement SEM/EDS analytical techniques

    NASA Astrophysics Data System (ADS)

    Schwoeble, A. J.; Strohmeier, Brian R.; Piasecki, John D.

    2010-06-01

    Gunshot residue particles (GSR) were examined using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) to illustrate the size, shape, morphology, and elemental composition normally observed in particulate resulting from a discharged firearm. Determining the presence of lead (Pb), antimony (Sb), and barium (Ba), barring other elemental tags, fused together in a single particle with the correct morphology, is all that is required for the positive identification of GSR. X-ray photoelectron spectroscopy (XPS), however, can reveal more detailed information on surface chemistry than SEM/EDS. XPS is a highly surface-sensitive (<= ~10 nm), non-destructive, analytical technique that provides qualitative information for all elements except hydrogen and helium. Nanometer-scale sampling depth and its ability to provide unique chemical state information make XPS a potential technique for providing important knowledge on the surface chemistry of GSR that complements results obtained from SEM/EDS analysis.

  7. Rock Outcrop Spectra

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The color image on the lower left shows a rock outcrop at Meridiani Planum, Mars. This image was taken by the panoramic camera on the Mars Exploration Rover Opportunity, looking north, and was acquired on the 4th sol, or martian day, of the rover's mission (Jan. 27, 2004). The yellow box outlines an area detailed in the top left image, which is a monochrome (single filter) image from the rover's panoramic camera. The top image uses solid colors to show several regions on or near the rock outcrop from which spectra were extracted: the dark soil above the outcrop (yellow), the distant horizon surface (aqua), a bright rock in the outcrop (green), a darker rock in the outcrop (red), and a small dark cobblestone (blue). Spectra from these regions are shown in the plot to the right.

  8. Barnacle Bill Spectra

    NASA Technical Reports Server (NTRS)

    1997-01-01

    These IMP spectra show the characteristics of the rock surface measured by the Alpha Proton X-Ray Spectrometer (blue), the soil trapped in pits on the rock surface (red), and the deposit of bright drift on the top of the rock. The area measured by the APXS has the properties expected for nearly unweathered igneous rock, and the soil trapped in the pits is intermediate to the unweathered rock and the highly weathered drift material.

  9. O(1S → 1D,3P) branching ratio as measured in the terrestrial nightglow

    NASA Astrophysics Data System (ADS)

    Slanger, T. G.; Cosby, P. C.; Sharpee, B. D.; Minschwaner, K. R.; Siskind, D. E.

    2006-12-01

    The branching ratio of the two optically forbidden atmospheric emission lines, O(1S - 1D) at 557.7 nm and O(1S - 3P) at 297.2 nm, is a fixed number in the upper atmosphere because the O(1S) level is common to both lines. The value for the ratio A(557.7)/A(297.2) currently recommended by NIST is 16.7, and the ratio found in the laboratory is somewhat larger. Field observations require space-based instruments, in which case calibration between the two wavelength regions is the critical issue. We circumvent this problem by using the O2(A-X) Herzberg I emission system as a bridge between the UV region below 310 nm and the ground-accessible region above that wavelength. These two spectral regions can be separately calibrated in terms of intensity, and the results of a disparate set of observations (satellite, rocket, ground-based sky spectra) lead to a quite consistent value of 9.8 ± 1.0 for A(557.7)/A(297.2). This conclusion has consequences for auroral and dayglow processes and for spectral calibration. It is particularly important to ascertain the cause of the substantial difference between this value and those from theory.

  10. Evidence for the eta_b(1S) in the Decay Upsilon(2S)-> gamma eta_b(1S)

    SciTech Connect

    Aubert, B.; Bona, M.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Lopez, L.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D.N.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; /LBL, Berkeley /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UCLA /UC, Riverside /UC, San Diego /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /Harvard U. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa U. /Iowa State U. /Johns Hopkins U. /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Karlsruhe U., EKP /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT, LNS /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /Mt. Holyoke Coll. /INFN, Naples /Naples U. /INFN, Naples /INFN, Naples /Naples U. /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /Pennsylvania U. /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rostock U. /Rutherford /DSM, DAPNIA, Saclay /South Carolina U. /SLAC /Stanford U., Phys. Dept. /SUNY, Albany /Tennessee U. /Texas U. /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U., IFIC /Victoria U. /Warwick U. /Wisconsin U., Madison

    2009-12-14

    We have performed a search for the {eta}{sub b}(1S) meson in the radiative decay of the {Upsilon}(2S) resonance using a sample of 91.6 million {Upsilon}(2S) events recorded with the BABAR detector at the PEP-II B factory at the SLAC National Accelerator Laboratory. We observe a peak in the photon energy spectrum at E{sub {gamma}} = 610.5{sub -4.3}{sup +4.5}(stat) {+-} 1.8(syst) MeV, corresponding to an {eta}{sub b}(1S) mass of 9392.9{sub -4.8}{sup +4.6}(stat) {+-} 1.9(syst) MeV/c{sup 2}. The branching fraction for the decay {Upsilon}(2S) {yields} {gamma}{eta}{sub b}(1S) is determined to be (4.2{sub -1.0}{sup +1.1}(stat) {+-} 0.9(syst)) x 10{sup -4}. The ratio {Beta}({Upsilon}(2S) {yields} {gamma}{eta}{sub b}(1S))/{Beta}({Upsilon}(3S) {yields} {gamma}{eta}{sub b}(1S)) = 0.89{sub -0.23}{sup +0.25}(stat){sub -0.16}{sup +0.12}(syst) is consistent with the ratio expected for magnetic dipole transitions to the {eta}{sub b}(1S) meson.

  11. SPECTRA. September 2011

    DTIC Science & Technology

    2011-09-01

    Transportation Services program with the Dragon capsule. (Credit: SpaceX /Chris Thompson) S p a c e c r a f t e n g in e e r in g spectra NRL...secondary payloads on board a Space Exploration Technologies ( SpaceX ), Inc., Falcon 9 launch vehicle. NRL’s nanosatellites are part of the CubeSat...Maryland. The primary payload launched aboard the SpaceX Falcon 9 was the Dragon capsule. Developed by SpaceX and sponsored by NASA’s Commercial Orbital

  12. Determinations of Photon Spectra

    DTIC Science & Technology

    1989-01-01

    COVERED O14. DATE OF REPORT (Year, Month, Day) 115. PAGE COUNT THESIS/ftFROW*W FROM TO 1989 1 54 16. SUPPLEMENTARY NOTATION A ?RQVk;U kOR 3UB LIC RELEASE...IAW AFR 190- 1 ERNEST A. HAYGOOD, 1st Lt, USAF Executive Officer, Civilian Institution ProQrams 17. COSATI CODES 18. SUBJECT TERMS (Continue on...spectra from measurements obtained with a sodium iodide counting system. A response matrix is computed by combining photon cross sections with

  13. Composition-dependent structure of polycrystalline magnetron-sputtered V-Al-C-N hard coatings studied by XRD, XPS, XANES and EXAFS.

    PubMed

    Krause, Bärbel; Darma, Susan; Kaufholz, Marthe; Mangold, Stefan; Doyle, Stephen; Ulrich, Sven; Leiste, Harald; Stüber, Michael; Baumbach, Tilo

    2013-08-01

    V-Al-C-N hard coatings with high carbon content were deposited by reactive radio-frequency magnetron sputtering using an experimental combinatorial approach, deposition from a segmented sputter target. The composition-dependent coexisting phases within the coating were analysed using the complementary methods of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine-structure spectroscopy (EXAFS). For the analysis of the X-ray absorption near-edge spectra, a new approach for evaluation of the pre-edge peak was developed, taking into account the self-absorption effects in thin films. Within the studied composition range, a mixed face-centred cubic (V,Al)(C,N) phase coexisting with a C-C-containing phase was observed. No indication of hexagonal (V,Al)(N,C) was found. The example of V-Al-C-N demonstrates how important a combination of complementary methods is for the detection of coexisting phases in complex multi-element coatings.

  14. Composition-dependent structure of polycrystalline magnetron-sputtered V–Al–C–N hard coatings studied by XRD, XPS, XANES and EXAFS

    PubMed Central

    Krause, Bärbel; Darma, Susan; Kaufholz, Marthe; Mangold, Stefan; Doyle, Stephen; Ulrich, Sven; Leiste, Harald; Stüber, Michael; Baumbach, Tilo

    2013-01-01

    V–Al–C–N hard coatings with high carbon content were deposited by reactive radio-frequency magnetron sputtering using an experimental combinatorial approach, deposition from a segmented sputter target. The composition-dependent coexisting phases within the coating were analysed using the complementary methods of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES) and extended X-ray absorption fine-structure spectroscopy (EXAFS). For the analysis of the X-ray absorption near-edge spectra, a new approach for evaluation of the pre-edge peak was developed, taking into account the self-absorption effects in thin films. Within the studied composition range, a mixed face-centred cubic (V,Al)(C,N) phase coexisting with a C–C-containing phase was observed. No indication of hexagonal (V,Al)(N,C) was found. The example of V–Al–C–N demonstrates how important a combination of complementary methods is for the detection of coexisting phases in complex multi-element coatings. PMID:24046506

  15. Peak position differences observed during XPS sputter depth profiling of the SEI on lithiated and delithiated carbon-based anode material for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Oswald, S.; Hoffmann, M.; Zier, M.

    2017-04-01

    The ability of delivering chemical information from peak shift phenomena has ever since made X-ray photoelectron spectroscopy (XPS) an ideal tool for material characterization in Li-ion batteries (LIB). Upon investigation, charging is inevitable as most of the chemical species involved are non-conducting. Thus, the binding energy (BE) scale must be corrected to allow an accurate interpretation of the results. This is usually done using the peak position of the ubiquitous surface carbon contamination detectable for all Li-ion battery relevant materials. We herein report on the occurrence of peak shift phenomena that can be observed when investigating surface layers on graphite anodes using sputter depth-profiling. These shifts, however, are not related to classical static electric charging, but are depending on the state of charge (lithiation) of the anode material. The observations presented are in agreement with previous findings on other Li-containing materials and are obviously caused by the presence of Li in its elemental state. As aging and failure mechanisms in LIBs are closely linked to electrolyte reaction products on electrode surfaces it is of high importance to draw the correct conclusions on their chemical origin from XP spectra. In order to avoid misinterpretation of the BE positions, implanted Ar can be used for identification of relevant peak positions and species involved in the phenomena observed.

  16. AFM AND XPS Characterization of Zinc-Aluminum Alloy Coatings with Attention to Surface Dross and Flow Lines

    NASA Astrophysics Data System (ADS)

    Harding, Felipe A.; Alarcon, Nelson A.; Toledo, Pedro G.

    Surfaces of various zinc-aluminum alloy (Zn-Al) coated steel samples are studied with attention to foreign surface dross by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS/ESCA). AFM topographic maps of zinc-aluminum alloy surfaces free of dross reveal the perfect nanoscale details of two kinds of dendrites: branched and globular. In all magnifications the dendrites appear smooth and, in general, very clean. XPS analysis of the extreme surface of a Zn-Al sample reveals Al, Zn, Si and O as the main components. The XPS results show no segregation or separation of phases other than those indicated by the ternary Al-Zn-Si diagram. For surfaces of Zn-Al plagued with impurities, high resolution AFM topographic maps reveal three situations: (1) areas with well-defined dendrites, relatively free of dross; (2) areas with small, millimeter-sized black spots known as dross; and (3) areas with large black stains, known as flow lines. Dendrite deformation and dross accumulation increase notably in the neighborhood, apparently clean to the naked eye, of dross or flow lines. XPS results of areas with dross and flow lines indicate unacceptable high concentration of Si and important Si phase separation. These results, in the light of AFM work, reveal that dross and flow lines are a consequence of a high local concentration of Si from high melting point silica and silicate impurities in the Zn-Al alloy source.

  17. Chemical and structural characterization of Zrsbnd Csbnd Nsbnd Ag coatings: XPS, XRD and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Calderon V, S.; Cavaleiro, A.; Carvalho, S.

    2015-08-01

    In this report Zrsbnd Csbnd Nsbnd Ag coatings produced by dual magnetron sputtering are characterized by X-ray photoelectron spectroscopy (XPS) and complemented by X-ray diffraction, scanning electron microscopy, electron-probe microanalysis and Raman spectroscopy, in order to determine the chemical bonds and phases formed during the production process. The results demonstrate the possibility of producing coatings with different silver content (0-16 at.%), in which zirconium carbonitrides (70-95 at.%), amorphous carbon nitride phases (0-16 at.%) and residual zirconium oxide phases (∼5 at.%) coexists with the metallic silver. The profile analysis evidenced a highly oxidized surface due to the affinity of Zr to form ZrO2, and silver segregation to the surface. The composition after Ar+ bombardment revealed the contribution of silver clusters and metallic silver, together with the mentioned phases that vary in content depending on the deposition parameters utilized. STEM images revealed silver nanoparticles distributed in the Zrsbnd Csbnd N matrix with sizes around 5-20 nm, as well as silver surface agglomeration with sizes <80 nm.

  18. RBS and XPS analyses of the composite calcium phosphate coatings for biomedical applications

    NASA Astrophysics Data System (ADS)

    Ide-Ektessabi, Ari; Yamaguchi, Tetsuro; Tanaka, Yoshikazu

    2005-12-01

    The calcium phosphate coatings on metallic implants are widely used for biomedical applications. The calcium phosphate coatings require mechanical strength, strong adhesion to the metallic implants, chemical stability and low dissolution into the human body fluid for stable functioning in the corrosive environment of the human body. In this study, a novel approach for improving the calcium phosphate coatings is utilized by adding trace metallic element into the coatings. We focused on teeth enamel, which is the hardest calcium phosphate tissue in the human body. Zn concentration increases exponentially from the interior to the surface of the enamel. As the Zn concentration increases, so the local hardness increases. Our previous studies suggest that Zn has influence on the hardness and other properties of enamel, calcium phosphate tissue. Calcium phosphate coatings doped with Zn was fabricated and characterized. The atomic composition and chemical state were investigated by using Rutherford backscattering spectroscopy (RBS) and X-ray photoelectron spectrometer (XPS), respectively. Scratch test was also carried out for measuring the adhesion of the coatings.

  19. XPS analysis and luminescence properties of thin films deposited by the pulsed laser deposition technique

    NASA Astrophysics Data System (ADS)

    Dolo, J. J.; Swart, H. C.; Coetsee, E.; Terblans, J. J.; Ntwaeaborwa, O. M.; Dejene, B. F.

    2010-04-01

    This paper presents the effect of substrate temperature and oxygen partial pressure on the photoluminescence (PL) intensity of the Gd2O2S:Tb3 + thin films that were grown by using pulsed laser deposition (PLD). The PL intensity increased with an increase in the oxygen partial pressure and substrate temperature. The thin film deposited at an oxygen pressure of 900 mTorr and substrate temperature of 900°C was found to be the best in terms of the PL intensity of the Gd2O2S:Tb3 + emission. The main emission peak due to the 5D4-7F5 transition of Tb was measured at a wavelength of 545 nm. The stability of these thin films under prolonged electron bombardment was tested with a combination of techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and Cathodoluminescence (CL) spectroscopy. It was shown that the main reason for the degradation in luminescence intensity under electron bombardment is the formation of a non-luminescent Gd2O3 layer, with small amounts of Gd2S3, on the surface.

  20. XPS analysis of 440C steel surfaces lubricated with perfluoropolyethers under sliding conditions in high vacuum

    NASA Technical Reports Server (NTRS)

    Herrera-Fierro, Pilar; Masuko, Masabumi; Jones, William R., Jr.; Pepper, Stephen V.

    1994-01-01

    This work presents the results of the X-Ray Photoelectron Spectroscopy (XPS) analysis of AISI 440C ball surfaces lubricated with perfluoropolyether (PFPE) oils after friction experiments under sliding conditions at high load in air and vacuum environments. The PFPE lubricants tested were Demnum S100, Fomblin Z-25, and Krytox 143AB. It was found that all the PFPE lubricants were degraded by sliding contact causing the formation of inorganic fluorides on the metallic surfaces and a layer of organic decomposition products. KRYTOX 143AB was the least reactive of the three lubricants tested. It was also found that metal fluoride formed at off-scar areas. This suggests the formation of reactive species, such as COF2 or R(sub f)COF, during sliding experiments, which can diffuse through the lubricant film and react with the metallic surfaces away from the contact region. Comparison of reference specimens before sliding with those that had undergone the sliding tests showed that the amount of non-degraded PFPE remaining on the surface of the balls after the sliding experiments was greater than that of the balls without sliding.

  1. XPS study of the effect of hydrocarbon contamination on polytetrafluoroethylene (teflon) exposed to atomic oxygen

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Wydeven, Theodore; Cormia, Robert D.

    1991-01-01

    The presence of hydrocarbon contamination on the surface of polytetrafluoroethylene (PTFE) markedly affects the oxygen uptake, and hence the wettability, of this polymer when exposed to an oxygen plasma. As revealed by X-ray photoelectron spectroscopy (XPS) analysis, the oxygen-to-carbon ratio (O/C) for such a polymer can increase sharply, and correspondingly the fluorine-to-carbon ratio (F/C) can decrease sharply, at very short exposure times; at longer times, however, such changes in the O/C and F/C ratios reverse direction, and these ratios then assume values similar to those of the unexposed PTFE. The greater the extent of hydrocarbon contamination in the PTFE, the larger are the amplitudes of the 'spikes' in the O/C- and F/C-exposure time plots. In contrast, a pristine PTFE experiences a very small, monotonic increase of surface oxidation or O/C ratio with time of exposure to oxygen atoms, while the F/C ratio is virtually unchanged from that of the unexposed polymer (2.0). Unless the presence of adventitious hydrocarbon is taken into account, anomalous surface properties relating to polymer adhesion may be improperly ascribed to PTFE exposed to an oxygen plasma.

  2. FTIR and XPS studies of surface chemistry of pyrite in flotation

    SciTech Connect

    Leppinen, J.; Laajalehto, K.; Kartio, I.; Suoninen, E.

    1995-12-31

    Efficient separation of pyrite is of great importance for the metallurgical performance of flotation processes. Presently, separation of pyrite by flotation is becoming more and more important for reduction of sulfur in coal. In this work Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) were used to study the surface chemistry of pyrite in depression, activation and xanthate adsorption under conditions of controlled potential. Modifications of pyrite surfaces after treatment with depressants (lime, sulfur dioxide, sodium cyanide) and after activation with metal ions (Cu, Pb) were studied. The principal adsorption product identified on pyrite was dixanthogen whose formation started at about +0.15 V and +0.25 V (vs, SHE) in ethyl and amyl xanthate solutions, respectively. Copper xanthate was formed on copper(II) activated pyrite. Activation mechanism of pyrite by copper(II) salts is likely to be electrochemical where copper occurs as copper(I) on the surface of pyrite. Effective depression is achieved by sulfur dioxide and sodium cyanide. Depression at high pH is due to formation of iron(III) hydroxides. Calcium ions do not affect the electrochemistry but adsorb on pyrite and reduce the surface sites for dixanthogen adsorption.

  3. Geometrical Characterization of Adenine And Guanine on Cu(110) By NEXAFS, XPS, And DFT Calculation

    SciTech Connect

    Furukawa, M.; Yamada, T.; Katano, S.; Kawai, M.; Ogasawara, H.; Nilsson, A.; /SLAC, SSRL /Stockholm U.

    2009-04-30

    Adsorption of purine DNA bases (guanine and adenine) on Cu(1 1 0) was studied by X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine-structure spectroscopy (NEXAFS), and density-functional theory (DFT) calculation. At coverages near 0.2 monolayers, Angular-resolved NEXAFS analysis revealed that adenine adsorbates lie almost flat and that guanine adsorbates are tilted up on the surface with the purine ring parallel to the atom rows of Cu(1 1 0). Referring to the previous studies on pyrimidine DNA bases [M. Furukawa, H. Fujisawa, S. Katano, H. Ogasawara, Y. Kim, T. Komeda, A. Nilsson, M. Kawai, Surf. Sci. 532-535 (2003) 261], the isomerization of DNA bases on Cu(1 1 0) was found to play an important role in the adsorption geometry. Guanine, thymine and cytosine adsorption have an amine-type nitrogen next to a carbonyl group, which is dehydrogenated into imine nitrogen on Cu(1 1 0). These bases are bonded by the inherent portion of - NH-CO - altered by conversion into enolic form and dehydrogenation. Adenine contains no CO group and is bonded to Cu(1 1 0) by participation of the inherent amine parts, resulting in nearly flatly-lying position.

  4. XPS for probing the dynamics of surface voltage and photovoltage in GaN

    NASA Astrophysics Data System (ADS)

    Sezen, Hikmet; Ozbay, Ekmel; Suzer, Sefik

    2014-12-01

    We describe application of two different data gathering techniques of XPS for probing the dynamics of surface voltage and surface photovoltage (SPV) developed in microseconds to seconds time-domain, in addition to the conventional steady-state measurements. For the longer (seconds to milliseconds) regime, capturing the data in the snapshot fashion is used, but for the faster one (down to microseconds), square wave (SQW) electrical pulses at different frequencies are utilized to induce and probe the dynamics of various processes causing the surface voltage, including the SPV, via the changes in the peak positions. The frequency range covers anywhere from 10-3 to 105 Hz for probing changes due to charging (slow), dipolar (intermediate), and electronic (fast) processes associated with the external stresses imposed. We demonstrate its power by application to n- and p-GaN, and discuss the chemical/physical information derived thereof. In addition, the method allows us to decompose and identify the peaks with respect to their charging nature for a composite sample containing both n- and p-GaN moieties.

  5. Modeling the PbI2 formation in perovskite solar cells using XRD/XPS patterns

    NASA Astrophysics Data System (ADS)

    Sohrabpoor, Hamed; Elyasi, Majid; Aldosari, Marouf; Gorji, Nima E.

    2016-09-01

    The impact of prolonged irradiation and air humidity on the stability of perovskite solar cells is modeled using X-ray diffraction and X-ray photoelectron spectroscopy patterns reported in the literature. Light or air-moisture causes the formation of a thin PbI2 or oxide defective layers (in nanoscale) at the interface of perovskite/hole-transport-layer or at the junction with metallic back contact. This thin layer blocks the carrier transport/passivation at the interfaces and cause degradation of device parameters. Variation in thickness of defective layers, changes the XRD and XPS peaks. This allows detection and estimation of the type, crystallinity and thickness of the defective layer. A simple model is developed here to extract the thickness of such thin defective layers formed in nanometer scale at the back region of several perovskite devices. Based on this information, corrected energy band diagram of every device before and after degradation/aging is drawn and discussed in order to obtain insight into the carrier transport and charge collection at the barrier region. In addition, graphene contacted perovskite devices are investigated showing that honey-comb network of graphene contact reduces the effect of aging leading to formation of a thinner defective layer at the perovskite surface compared to perovskite devices with conventional inorganic contacts i.e. Au, Al.

  6. Raman and XPS analyses of pristine and annealed N-doped double-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Shi, Lei; Sauer, Markus; Domanov, Oleg; Rohringer, Philip; Ayala, Paola; Pichler, Thomas

    2015-11-01

    N-doped single/multi-walled carbon nanotubes (CNTs) were studied for long time from synthesis to properties. However, the stability of N in the CNT lattice still needs further developments. In this work, to obtain more stable N-doped CNTs, concentric double-walled (DW) CNTs with more N were synthesized using benzylamine as C and N source. In order to test the stability of N-doped DWCNTs, high-temperature annealing in vacuum was performed. By XPS and Raman spectroscopic measurements, we found that the N-doped DWCNTs are still stable under 1500 $\\,^{\\circ}\\mathrm{C}$: the graphitic N does not change at all, the molecular N is partly removed, and the pyridinic N ratio greatly increases by more than two times. The reason could be that the N atoms from the surrounded N-contained materials combine into the CNT lattice during the annealing. Compared with the undoped DWCNTs, no Raman frequency shift was observed for the RBM, the G-band, and the G'-band of the N-doped DWCNTs.

  7. XPS analysis of the effect of fillers on PTFE transfer film development in sliding contacts

    NASA Technical Reports Server (NTRS)

    Blanchet, T. A.; Kennedy, F. E.; Jayne, D. T.

    1993-01-01

    The development of transfer films atop steel counterfaces in contact with unfilled and bronze-filled PTFE has been studied using X-ray photoelectron spectroscopy. The sliding apparatus was contained within the vacuum of the analytical system, so the effects of the native oxide, hydrocarbon, and adsorbed gaseous surface layers of the steel upon the PTFE transfer behavior could be studied in situ. For both the filled and the unfilled PTFE, cleaner surfaces promoted greater amounts of transfer. Metal fluorides, which formed at the transfer film/counterface interface, were found solely in cases where the native oxide had been removed to expose the metallic surface prior to sliding. These fluorides also were found at clean metal/PTFE interfaces formed in the absence of frictional contact. A fraction of these fluorides resulted from irradiation damage inherent in XPS analysis. PTFE transfer films were found to build up with repeated sliding passes, by a process in which strands of transfer filled in the remaining counterface area. Under these reported test conditions, the transfer process is not expected to continue atop previously deposited transfer films. The bronze-filled composite generated greater amounts of transfer than the unfilled PTFE. The results are discussed relative to the observed increase in wear resistance imparted to PTFE by a broad range of inorganic fillers.

  8. XPS and STM studies of the oxidation of hydrogen chloride at Cu(100) surfaces

    NASA Astrophysics Data System (ADS)

    Altass, Hatem; Carley, Albert F.; Davies, Philip R.; Davies, Robert J.

    2016-08-01

    The dissociative chemisorption of HCl on clean and oxidized Cu(100) surfaces has been investigated using x-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). Whereas the dissociation of HCl at the clean surface is limited to the formation of a (√ 2 × √ 2)-R45° Cl(a) monolayer, the presence of surface oxygen removes this barrier, leading to chlorine coverages up to twice that obtained at the clean surface. Additional features in the STM images that appear at these coverages are tentatively assigned to the nucleation of CuCl islands. The rate of reaction of the HCl was slightly higher on the oxidized surface but unaffected by the initial oxygen concentration or the availability of clean copper sites. Of the two distinct domains of adsorbed oxygen identified at room temperature on the Cu(100) surfaces, the (√ 2 × √ 2)-R45° structure reacts slightly faster with HCl than the missing row (√ 2 × 2 √ 2)-R45° O(a) structure. The results address the first stages in the formation of a copper chloride and present an interesting comparison with the HCl/O(a) reaction at Cu(110) surfaces, where oxygen also increased the extent of HCl reactions. The results emphasize the importance of the exothermic reaction to form water in the HCl/O(a) reaction on copper.

  9. Interfacial chemistry of a perfluoropolyether lubricant studied by XPS and TDS

    NASA Technical Reports Server (NTRS)

    Herrera-Fierro, Pilar C.; Jones, William R., Jr.; Pepper, Stephen V.

    1992-01-01

    The interfacial chemistry of Fomblin Z25, a commercial perfluoropolyether used as lubricant for space applications, with different metallic surfaces: 440C steel, gold and aluminum was studied. Thin layers of Fomblin Z25 were evaporated onto the oxide-free substrates and the interfacial chemistry studied using XPS and TDS. The reactions were induced by heating the substrate and by rubbing the substrate with a steel ball. Gold was found to be completely unreactive towards Fomblin at any temperature. Reaction at room temperature was observed only in the case of the aluminum substrate, the most reactive towards Fomblin Z25 of the substrates studied. It was necessary to heat the 440C steel substrate to 190 degree C to induce decomposition of the fluid. The degradation of the fluid was indicated by the formation of a debris layer at the interface. This debris layer, composed of inorganic and organic reaction products, when completely formed, passivated the surface from further attack to the Fromblin on top. The tribologically induced reactions on 440C steel formed a debris layer of similar chemical characteristics to the thermally induced layer. In all cases, the degradation reaction resulted in preferential consumption of the difluoroformyl carbon (-OCF2O-).

  10. Control spectra for Quito

    NASA Astrophysics Data System (ADS)

    Aguiar, Roberto; Rivas-Medina, Alicia; Caiza, Pablo; Quizanga, Diego

    2017-03-01

    The Metropolitan District of Quito is located on or very close to segments of reverse blind faults, Puengasí, Ilumbisí-La Bota, Carcelen-El Inca, Bellavista-Catequilla and Tangahuilla, making it one of the most seismically dangerous cities in the world. The city is divided into five areas: south, south-central, central, north-central and north. For each of the urban areas, elastic response spectra are presented in this paper, which are determined by utilizing some of the new models of the Pacific Earthquake Engineering Research Center (PEER) NGA-West2 program. These spectra are calculated considering the maximum magnitude that could be generated by the rupture of each fault segment, and taking into account the soil type that exists at different points of the city according to the Norma Ecuatoriana de la Construcción (2015). Subsequently, the recurrence period of earthquakes of high magnitude in each fault segment is determined from the physical parameters of the fault segments (size of the fault plane and slip rate) and the pattern of recurrence of type Gutenberg-Richter earthquakes with double truncation magnitude (Mmin and Mmax) is used.

  11. Theoretical Studies of Molecular Spectra

    NASA Technical Reports Server (NTRS)

    McKay, Christopher (Technical Monitor); Freedman, Richard S.

    2002-01-01

    This summary describes the research activities of the principal investigator during the reporting period. The research includes spectroscopy, management of molecular databases, and generation of spectral line profiles and opacity data. The spectroscopy research includes oxygen broadening of nitric oxide (NO), analysis of CO2 spectra, analysis of HNO3 spectra, and analysis of CO spectra.

  12. Continuum Fitting HST QSO Spectra

    NASA Technical Reports Server (NTRS)

    Tytler, David; Oliversen, Ronald J. (Technical Monitor)

    2002-01-01

    The Principal Component Analysis (PCA) method which we are using to fit and describe QSO spectra relies upon the fact that QSO continuum are generally very smooth and simple except for emission and absorption lines. To see this we need high signal-to-noise (S/N) spectra of QSOs at low redshift which have relatively few absorption lines in the Lyman-a forest. We need a large number of such spectra to use as the basis set for the PCA analysis which will find the set of principal component spectra which describe the QSO family as a whole. We have found that too few HST spectra have the required S/N and hence we need to supplement them with ground based spectra of QSOs at higher redshift. We have many such spectra and we have been working to make them suitable for this analysis. We have concentrated on this topic since 12/15/01.

  13. Intensity oscillations in the carbon 1s ionization cross sections of 2-butyne

    SciTech Connect

    Carroll, Thomas X.; Zahl, Maria G.; Borve, Knut J.; Saethre, Leif J.; Decleva, Piero; Ponzi, Aurora; Kas, Joshua J.; Vila, Fernando D.; Rehr, John J.; Thomas, T. Darrah

    2013-06-21

    Carbon 1s photoelectron spectra for 2-butyne (CH{sub 3}C{identical_to}CCH{sub 3}) measured in the photon energy range from threshold to 150 eV above threshold show oscillations in the intensity ratio C2,3/C1,4. Similar oscillations have been seen in chloroethanes, where the effect has been attributed to EXAFS-type scattering from the substituent chlorine atoms. In 2-butyne, however, there is no high-Z atom to provide a scattering center and, hence, oscillations of the magnitude observed are surprising. The results have been analyzed in terms of two different theoretical models: a density-functional model with B-spline atom-centered functions to represent the continuum electrons and a multiple-scattering model using muffin-tin potentials to represent the scattering centers. Both methods give a reasonable description of the energy dependence of the intensity ratios.

  14. XPS determination of Mn oxidation states in Mn (hydr)oxides

    SciTech Connect

    Ilton, Eugene S.; Post, Jeffrey E.; Heaney, Peter J.; Ling, Florence T.; Kerisit, Sebastien N.

    2016-03-01

    Hydrous manganese oxides are an important class of minerals that help regulate the geochemical redox cycle in near-surface environments and are also considered to be promising catalysts for energy applications such as the oxidation of water. A complete characterization of these minerals is required to better understand their catalytic activity. In this contribution an empirical methodology using X-ray photoelectron spectroscopy (XPS) is developed to quantify the oxidation state of hydrous multivalent manganese oxides with an emphasis on birnessite, a common layered structure that occurs readily in Nature but is also the oxidized endmember in biomimetic water-oxidation catalysts. The Mn2p3/2, Mn3p, and Mn3s lines of near monovalent Mn(II), Mn(III), and Mn(IV) oxides were fit with component peaks; after the best fit was obtained the relative widths, heights and binding energies of the components were fixed. Unknown multivalent samples were fit such that binding energies, intensities, and widths of each oxidation state, composed of a packet of correlated component peaks, were allowed vary. whereas widths were constrained to maintain the difference between the standards. Both average and individual mole fraction oxidation states for all three energy levels were strongly correlated with close agreement between Mn3s and Mn3p, whereas Mn2p3/2 gave systematically more reduced results. Limited stoichiometric analyses were consistent with Mn3p and Mn3s. Further, evidence indicates the shape of the Mn3p line was less sensitive to the bonding environment than Mn2p. Consequently, fitting the Mn3p and Mn3s lines yields robust quantification of oxidation states over a range of hydrous Mn oxide polytypes and compositions. In contrast, a common method for determining oxidation states that utilizes the multiplet splitting of the Mn3s line is not appropriate for birnessites.

  15. Carbonaceous matter in peridotites and basalts studied by XPS, SALI, and LEED

    SciTech Connect

    Tingle, T.N. SRI International, Menlo Park, CA ); Mathez, E.A. ); Hochella, M.F. Jr. )

    1991-05-01

    Carbonaceous matter in peridotite xenoliths and basalt from the Hualalai Volcano, in a basalt glass collected directly from an active lava lake on the east rift of Kilauea, in garnet and diopside megacrysts from the Jagersfontein kimberlite, and in gabbros from the Stillwater and Bushveld Complexes has been studied by X-ray photoelectron spectroscopy (XPS), thermal-desorption surface analysis by laser ionization (SALI), and low-energy electron diffraction (LEED). The basalt and two of the four xenoliths from Hualalai and both Jagersfontein megacrysts yielded trace quantities ({le}10 nanomoles) of organic compounds on heating to 700C. Organics were not detected in the rocks from the layered intrusions, and neither carbonaceous matter nor organics were detected in the glass from the lava lake. Where detected, organics appear to be associated with carbonaceous films on microcrack surfaces. Carbonaceous matter exists as films less than a few nm thick and particles up to 20 {mu}m across, both of which contain elements expected to be present in significant quantities in magmatic vapors, namely Si, alkalis, halogens, N, and transition metals. LEED studies suggest that the carbonaceous films are amorphous. The data suggest two possible mechanisms for the formation of the organics. One is that they are a product of abiotic heterogeneous catalysis of volcanic gas on new, chemically active mineral surfaces formed by fracturing during cooling. Alternatively, organics may have been assimilated into the volcanic gases prior to eruption and then deposited on cracks formed during eruption and cooling. In any case, there is no evidence to suggest that the organics represent laboratory or field biogenic contamination.

  16. Magic Wavelength for the Hydrogen 1S-2S Transition

    NASA Astrophysics Data System (ADS)

    Kawasaki, Akio

    2016-05-01

    The state of the art precision measurement of the transition frequencies of neutral atoms is performed with atoms trapped by the magic wavelength optical lattice that cancels the ac Stark shift of the transitions. Trapping with magic wavelength lattice is also expected to improve the precision of the hydrogen 1S-2S transition frequency, which so far has been measured only with the atomic beam. In this talk, I discuss the magic wavelength for the hydrogen 1S-2S transition, and the possibility of implementing the optical lattice trapping for hydrogen. Optical trapping of hydrogen also opens the way to perform magnetic field free spectroscopy of antihydrogen for the test of CPT theorem.

  17. Precision frequency measurement of 1S0-3P1 intercombination lines of Sr isotopes

    NASA Astrophysics Data System (ADS)

    Liu, Hui; Gao, Feng; Ye-Bing, Wang; Xiao, Tian; Jie, Ren; Ben-Quan, Lu; Qin-Fang, Xu; Yu-Lin, Xie; Hong, Chang

    2015-01-01

    We report on frequency measurement of the intercombination (5s2)1S0-(5s5p)3P1 transition of the four natural isotopes of strontium, including 88Sr (82.58%), 87Sr (7.0%), 86Sr (9.86%), and 84Sr (0.56%). A narrow-linewidth laser that is locked to an ultra-low expansion (ULE) optical cavity with a finesse of 12000 is evaluated at a linewidth of 200 Hz with a fractional frequency drift of 2.8×10-13 at an integration time of 1 s. The fluorescence collector and detector are specially designed, based on a thermal atomic beam. Using a double-pass acousto-optic modulator (AOM) combined with a fiber and laser power stabilization configuration to detune the laser frequency enables high signal-to-noise ratios and precision saturated spectra to be obtained for the six transition lines, which allows us to determine the transition frequency precisely. The optical frequency is measured using an optical frequency synthesizer referenced to an H maser. Both the statistical values and the final values, including the corrections and uncertainties, are derived for a comparison with the values given in other works. Project supported by the National Natural Science Foundation of China (Grant No. 61127901) and the Key Project of the Chinese Academy of Sciences (Grant No. KJZD-EW-W02).

  18. Sequencing BPS spectra

    NASA Astrophysics Data System (ADS)

    Gukov, Sergei; Nawata, Satoshi; Saberi, Ingmar; Stošić, Marko; Sułkowski, Piotr

    2016-03-01

    This paper provides both a detailed study of color-dependence of link homologies, as realized in physics as certain spaces of BPS states, and a broad study of the behavior of BPS states in general. We consider how the spectrum of BPS states varies as continuous parameters of a theory are perturbed. This question can be posed in a wide variety of physical contexts, and we answer it by proposing that the relationship between unperturbed and perturbed BPS spectra is described by a spectral sequence. These general considerations unify previous applications of spectral sequence techniques to physics, and explain from a physical standpoint the appearance of many spectral sequences relating various link homology theories to one another. We also study structural properties of colored HOMFLY homology for links and evaluate Poincaré polynomials in numerous examples. Among these structural properties is a novel "sliding" property, which can be explained by using (refined) modular S-matrix. This leads to the identification of modular transformations in Chern-Simons theory and 3d {N}=2 theory via the 3d/3d correspondence. Lastly, we introduce the notion of associated varieties as classical limits of recursion relations of colored superpolynomials of links, and study their properties.

  19. Sequencing BPS spectra

    SciTech Connect

    Gukov, Sergei; Nawata, Satoshi; Saberi, Ingmar; Stošić, Marko; Sułkowski, Piotr

    2016-03-02

    In this article, we provide both a detailed study of color-dependence of link homologies, as realized in physics as certain spaces of BPS states, and a broad study of the behavior of BPS states in general. We consider how the spectrum of BPS states varies as continuous parameters of a theory are perturbed. This question can be posed in a wide variety of physical contexts, and we answer it by proposing that the relationship between unperturbed and perturbed BPS spectra is described by a spectral sequence. These general considerations unify previous applications of spectral sequence techniques to physics, and explain from a physical standpoint the appearance of many spectral sequences relating various link homology theories to one another. We also study structural properties of colored HOMFLY homology for links and evaluate Poincar e polynomials in numerous examples. Among these structural properties is a novel "sliding" property, which can be explained by using (re fined) modular S-matrix. This leads to the identi fication of modular transformations in Chern-Simons theory and 3d N = 2 theory via the 3d/3d correspondence. In conclusion, we introduce the notion of associated varieties as classical limits of recursion relations of colored superpolynomials of links, and study their properties.

  20. Sequencing BPS spectra

    DOE PAGES

    Gukov, Sergei; Nawata, Satoshi; Saberi, Ingmar; ...

    2016-03-02

    In this article, we provide both a detailed study of color-dependence of link homologies, as realized in physics as certain spaces of BPS states, and a broad study of the behavior of BPS states in general. We consider how the spectrum of BPS states varies as continuous parameters of a theory are perturbed. This question can be posed in a wide variety of physical contexts, and we answer it by proposing that the relationship between unperturbed and perturbed BPS spectra is described by a spectral sequence. These general considerations unify previous applications of spectral sequence techniques to physics, and explainmore » from a physical standpoint the appearance of many spectral sequences relating various link homology theories to one another. We also study structural properties of colored HOMFLY homology for links and evaluate Poincar e polynomials in numerous examples. Among these structural properties is a novel "sliding" property, which can be explained by using (re fined) modular S-matrix. This leads to the identi fication of modular transformations in Chern-Simons theory and 3d N = 2 theory via the 3d/3d correspondence. In conclusion, we introduce the notion of associated varieties as classical limits of recursion relations of colored superpolynomials of links, and study their properties.« less

  1. Interpreting Chromosome Aberration Spectra

    NASA Technical Reports Server (NTRS)

    Levy, Dan; Reeder, Christopher; Loucas, Bradford; Hlatky, Lynn; Chen, Allen; Cornforth, Michael; Sachs, Rainer

    2007-01-01

    Ionizing radiation can damage cells by breaking both strands of DNA in multiple locations, essentially cutting chromosomes into pieces. The cell has enzymatic mechanisms to repair such breaks; however, these mechanisms are imperfect and, in an exchange process, may produce a large-scale rearrangement of the genome, called a chromosome aberration. Chromosome aberrations are important in killing cells, during carcinogenesis, in characterizing repair/misrepair pathways, in retrospective radiation biodosimetry, and in a number of other ways. DNA staining techniques such as mFISH ( multicolor fluorescent in situ hybridization) provide a means for analyzing aberration spectra by examining observed final patterns. Unfortunately, an mFISH observed final pattern often does not uniquely determine the underlying exchange process. Further, resolution limitations in the painting protocol sometimes lead to apparently incomplete final patterns. We here describe an algorithm for systematically finding exchange processes consistent with any observed final pattern. This algorithm uses aberration multigraphs, a mathematical formalism that links the various aspects of aberration formation. By applying a measure to the space of consistent multigraphs, we will show how to generate model-specific distributions of aberration processes from mFISH experimental data. The approach is implemented by software freely available over the internet. As a sample application, we apply these algorithms to an aberration data set, obtaining a distribution of exchange cycle sizes, which serves to measure aberration complexity. Estimating complexity, in turn, helps indicate how damaging the aberrations are and may facilitate identification of radiation type in retrospective biodosimetry.

  2. Initial stages of oxide formation on the Zr surface at low oxygen pressure: An in situ FIM and XPS study

    PubMed Central

    Bespalov, I.; Datler, M.; Buhr, S.; Drachsel, W.; Rupprechter, G.; Suchorski, Y.

    2015-01-01

    An improved methodology of the Zr specimen preparation was developed which allows fabrication of stable Zr nanotips suitable for FIM and AP applications. Initial oxidation of the Zr surface was studied on a Zr nanotip by FIM and on a polycrystalline Zr foil by XPS, both at low oxygen pressure (10−8–10−7 mbar). The XPS data reveal that in a first, fast stage of oxidation, a Zr suboxide interlayer is formed which contains three suboxide components (Zr+1, Zr+2 and Zr+3) and is located between the Zr surface and a stoichiometric ZrO2 overlayer that grows in a second, slow oxidation stage. The sole suboxide layer has been observed for the first time at very early states of the oxidation (oxygen exposure ≤4 L). The Ne+ FIM observations are in accord with a two stage process of Zr oxide formation. PMID:25766998

  3. Location and Visualization of Working p-n and/or n-p Junctions by XPS

    PubMed Central

    Copuroglu, Mehmet; Caliskan, Deniz; Sezen, Hikmet; Ozbay, Ekmel; Suzer, Sefik

    2016-01-01

    X-ray photoelectron spectroscopy (XPS) is used to follow some of the electrical properties of a segmented silicon photodetector, fabricated in a p-n-p configuration, during operation under various biasing configurations. Mapping of the binding energy position of Si2p reveals the shift in the position of the junctions with respect to the polarity of the DC bias applied. Use of squared and triangular shaped wave excitations, while recording XPS data, allows tapping different electrical properties of the device under normal operational conditions, as well as after exposing parts of it to harsh physical and chemical treatments. Unique and chemically specific electrical information can be gained with this noninvasive approach which can be useful especially for localized device characterization and failure analyses. PMID:27582318

  4. XPS identification of surface-initiated polymerisation during monomer transfer moulding of poly(ɛ-caprolactone)/Bioglass ® fibre composite

    NASA Astrophysics Data System (ADS)

    Jiang, G.; Walker, G. S.; Jones, I. A.; Rudd, C. D.

    2005-12-01

    In this work, X-ray photoelectron spectroscopy (XPS) was demonstrated to be a useful method to characterise surface-initiated polymerisation. Both E-glass fibre and Bioglass ® fibre were treated using 3-aminopropyltrimethoxysilane (and propyltrimethoxysilane as a control) and then they were used as a reinforcement, respectively, in monomer transfer moulding to prepare poly(ɛ-caprolactone)/glass fibre composites with stannous octoate as the catalyst for ɛ-caprolactone polymerisation. The fibre was extracted and then analysed using XPS to probe the presence of PCL chemically bonded to the glass fibre surface. Both tin and PCL were detected on the surface of the fibres sized with 3-aminopropyltrimethoxysilane, confirming surface-initiated polymerisation of ɛ-caprolactone.

  5. Location and Visualization of Working p-n and/or n-p Junctions by XPS

    NASA Astrophysics Data System (ADS)

    Copuroglu, Mehmet; Caliskan, Deniz; Sezen, Hikmet; Ozbay, Ekmel; Suzer, Sefik

    2016-09-01

    X-ray photoelectron spectroscopy (XPS) is used to follow some of the electrical properties of a segmented silicon photodetector, fabricated in a p-n-p configuration, during operation under various biasing configurations. Mapping of the binding energy position of Si2p reveals the shift in the position of the junctions with respect to the polarity of the DC bias applied. Use of squared and triangular shaped wave excitations, while recording XPS data, allows tapping different electrical properties of the device under normal operational conditions, as well as after exposing parts of it to harsh physical and chemical treatments. Unique and chemically specific electrical information can be gained with this noninvasive approach which can be useful especially for localized device characterization and failure analyses.

  6. An XPS (X-Ray Photoelectron Spectroscopy) Study of the Composition of Thin Polyimide Films Formed by Vapor Deposition.

    DTIC Science & Technology

    1987-07-15

    1985) 2857. 13. B. D. Silverman, J. W. Bartha, J. G. Clabes, P. S Ho and A. R. Rossi, J. Polym . Sci. Part A 24 (1986) 3325. 14. E. Cartier , P. Pfluger...Benzenetetracarboxylic anhydride (PMDA), imidization, polymer , in situ, X-ray Photoelectron Spectroscopy (XPS),Cu(111) 20. ABSTRACT (Continue an...ODA) and 1,2,4,5 Benzenetetracarboxylic anhydride (PMDA). The imidization reaction leading to polymer formation was followed in situ with X-ray

  7. Laboratory simulation of dust spectra

    NASA Technical Reports Server (NTRS)

    Allamandola, L. J.; Sandford, S. A.

    1988-01-01

    Laboratory studies of the IR spectra of interstellar dust are reviewed. Studies of the absorption spectra of dense molecular clouds are discussed, including methods to produce interstellar ice analogues, simulations of astronomical spectra, and IR absorption features caused by ices. Comparisons are made between observational and experimental results of interstellar dust studies. Also, the interstellar emission features associated with dusty regions exposed to UV radiation are examined, including bands related to PAHs and PAH-related materials. It is shown that interstellar spectra are more consistant with emission from free PAHs than with emission from particles.

  8. Electron-impact core excitation of SF6. I. S 2p, S 2s, and F 1s spectroscopy

    NASA Astrophysics Data System (ADS)

    Francis, James T.; Turci, Cássia C.; Tyliszczak, Tolek; de Souza, G. Gerson B.; Kosugi, Nobuhiro; Hitchcock, Adam P.

    1995-12-01

    Electron energy-loss spectra (EELS) of SF6 have been recorded in the region of S 2p, S 2s, and F 1s excitation, using both dipole and nondipole electron-scattering conditions. Impact energies between 700 and 3200 eV and scattering angles between 0° and 30° were used. Relative to dipole EELS or photoabsorption, there are large intensity redistributions in both the S 2p and S 2s spectra under nondipole conditions. In contrast, the F 1s spectrum is essentially the same in near-dipole and nondipole scattering regimes. A higher-order electric multiple S 2p spectra feature is observed at 181 eV. It has an unusual multipeaked line shape whose components are more closely spaced than the typical 1.15-eV S 2p spin-orbit splitting. It is attributed to the overlap of several quadrupole-coupled states, which are likely associated with the [S 2p(t1u)-1,t1u] configuration. Ab initio self-consistent field calculations for various open-shell S 2p excited states are used to assist spectral assignments.

  9. Determination of the 1s2{\\ell }2{{\\ell }}^{\\prime } state production ratios {{}^{4}P}^{o}/{}^{2}P, {}^{2}D/{}^{2}P and {{}^{2}P}_{+}/{{}^{2}P}_{-} from fast (1{s}^{2},1s2s\\,{}^{3}S) mixed-state He-like ion beams in collisions with H2 targets

    NASA Astrophysics Data System (ADS)

    Benis, E. P.; Zouros, T. J. M.

    2016-12-01

    New results are presented on the ratio {R}m={σ }{T2p}( {}4P)/{σ }{T2p}({}2P) concerning the production cross sections of Li-like 1s2s2p quartet and doublet P states formed in energetic ion-atom collisions by single 2p electron transfer to the metastable 1s2s {}3S component of the He-like ion beam. Spin statistics predict a value of R m = 2 independent of the collision system in disagreement with most reported measurements of {R}m≃ 1{--}9. A new experimental approach is presented for the evaluation of R m having some practical advantages over earlier approaches. It also allows for the determination of the separate contributions of ground- and metastable-state beam components to the measured spectra. Applying our technique to zero-degree Auger projectile spectra from 4.5 MeV {{{B}}}3+ (Benis et al 2002 Phys. Rev. A 65 064701) and 25.3 MeV {{{F}}}7+ (Zamkov et al 2002 Phys. Rev. A 65 062706) mixed state (1{s}2 {}1S,1s2s {}3S) He-like ion collisions with H2 targets, we report new values of {R}m=3.5+/- 0.4 for boron and {R}m=1.8+/- 0.3 for fluorine. In addition, the ratios of {}2D/{}2P and {{}2P}+/{{}2P}- populations from either the metastable and/or ground state beam component, also relevant to this analysis, are evaluated and compared to previously reported results for carbon collisions on helium (Strohschein et al 2008 Phys. Rev. A 77 022706) including a critical comparison to theory.

  10. A quantitative model and the experimental evaluation of the liquid fuel layer for the downward flame spread of XPS foam.

    PubMed

    Luo, Shengfeng; Xie, Qiyuan; Tang, Xinyi; Qiu, Rong; Yang, Yun

    2017-05-05

    The objective of this work is to investigate the distinctive mechanisms of downward flame spread for XPS foam. It was physically considered as a moving down of narrow pool fire instead of downward surface flame spread for normal solids. A method was developed to quantitatively analyze the accumulated liquid fuel based on the experimental measurement of locations of flame tips and burning rates. The results surprisingly showed that about 80% of the generated hot liquid fuel remained in the pool fire during a certain period. Most of the consumed solid XPS foam didn't really burn away but transformed as the liquid fuel in the downward moving pool fire, which might be an important promotion for the fast fire development. The results also indicated that the dripping propensity of the hot liquid fuel depends on the total amount of the hot liquid accumulated in the pool fire. The leading point of the flame front curve might be the breach of the accumulated hot liquid fuel if it is enough for dripping. Finally, it is suggested that horizontal noncombustible barriers for preventing the accumulation and dripping of liquid fuel are helpful for vertical confining of XPS fire.

  11. Drying methods for XPS analysis of PureVision™, Focus ® Night&Day™ and conventional hydrogel contact lenses

    NASA Astrophysics Data System (ADS)

    Karlgard, Caroline C. S.; Sarkar, Dilip K.; Jones, Lyndon W.; Moresoli, Christine; Leung, K. T.

    2004-05-01

    The surface composition of hydrogel contact lenses that contain silicon-based monomers, PureVision™ (balafilcon A) and Focus ® Night&Day™ (lotrafilcon A), were investigated by X-ray photoelectron spectroscopy (XPS). Conventional and daily disposable hydrogel lenses based on hydroxyethyl methacrylate (HEMA) were also studied, with the commonly prescribed 1-day Acuvue ® lens (etafilcon A) used as a control. All the lenses were pre-washed and dehydrated by three different methods, including drying in air, drying in nitrogen or freezing with subsequent freeze-drying, before the XPS analysis. The lenses dried in air had more impurities on the surface, and the lenses that were freeze-dried lost transparency, suggesting that drying lenses in nitrogen is the preferred preparation method for XPS analysis. Surface compositions for all lens materials were obtained and this data can be used as a control/base-value for future analysis of the interactions of soft contact lens materials with chemicals such as drugs or tear components.

  12. Study of the influence of the acrylic acid plasma parameters on silicon and polyurethane substrates using XPS and AFM

    NASA Astrophysics Data System (ADS)

    Vilani, C.; Weibel, D. E.; Zamora, R. R. M.; Habert, A. C.; Achete, C. A.

    2007-10-01

    XPS and AFM have been used to investigate surface modifications produced by acrylic acid (AA) vapor plasma treatment of silicon (Si)(1 0 0) substrates and polyurethanes (PUs) membranes. XPS analyses of Si and PUs treated substrates at low plasma power (5-20 W) revealed the formation of a thin film on the surfaces, which chemically resembles the poly(acrylic acid) film conventionally synthesised. No signal of the Si substrate could be seen under these low plasma power applications on silicon. However, when the plasma power is higher than 30 W one can clearly see XPS silicon signatures. AFM measurements of silicon substrates treated with AA plasma at low power (5-20 W) showed the formation of a thin polymer film of about 220-55 nm thickness. Further, applications of high plasma power (30-100 W) displayed a marked difference from low plasma modifications and it was found sputtering of the silicon substrate. Pervaporation results of AA plasma treated PUs membranes revealed that the selectivity for the separation of methanol from methyl- t-butyl ether is higher at 100 W and 1 min treatment time, than the other conditions studied. This last finding is discussed concerning the surface modifications produced on plasma treated silicon substrates and PU membranes.

  13. Thorium effect on the oxidation of uranium: Photoelectron spectroscopy (XPS/UPS) and cyclic voltammetry (CV) investigation on (U1 - xThx)O2 (x = 0 to 1) thin films

    NASA Astrophysics Data System (ADS)

    Cakir, P.; Eloirdi, R.; Huber, F.; Konings, R. J. M.; Gouder, T.

    2017-01-01

    Thin films of U1- xThxO2 (x = 0 to 1) have been deposited via reactive DC sputter technique and characterized by X-ray/Ultra-violet Photoelectron Spectroscopy (XPS/UPS), X-ray Powder Diffractometer (XRD) and Cyclic Voltammetry (CV) in order to understand the effect of Thorium on the oxidation mechanism. During the deposition, the competition between uranium and thorium for oxidation showed that thorium has a much higher affinity for oxygen. Deposition conditions, time and temperature were also the subject of this study, to look at the homogeneity and the stability of the films. While core level and valence band spectra were not altered by the time of deposition, temperature was affecting the oxidation state of uranium and the valence band due to the mobility increase of oxygen through the film. X-ray diffraction patterns, core level spectra obtained for U1 - xThxO2 versus the composition showed that lattice parameters follow the Vegard's law and together with the binding energies of U-4f and Th-4f are in good agreement with literature data obtained on bulk compounds. To study the effect of thorium on the oxidation of U1 - xThxO2 films, we used CV experiments at neutral pH of a NaCl solution in contact with air. The results indicated that thorium has an effect on the uranium oxidation as demonstrated by the decrease of the current of the oxidation peak of uranium. XPS measurements made before and after the CV, showed a relative enrichment of thorium at the extent of uranium at the surface supporting the formation at a longer term of a thorium protective layer at the surface of uranium-thorium mixed oxide.

  14. Satellite spectra for helium-like titanium

    SciTech Connect

    Bely-Dubac, F.; Faucher, P.; Steeman-Clark, L.; Dubau, J.; Cammy-Val, C.; Bitter, M.; Hill, K.W.; von Goeler, S.

    1982-06-01

    Wavelengths and atomic parameters for both dielectronic and inner-shell satellite lines of the type ls/sup 2/ nl - 1s2l' nl, with n = 2, 3, and 4, have been calculated for Ti XX. The atomic data were calculated in a multiconfiguration intermediate coupling scheme and are compared with previous results for n = 2. The intensities of the higher n satellites are derived from these data, and thus an estimate of the contribution of the unresolved dielectronic satellites to the resonance line is obtained. Direct excitation rates are also given for the resonance, intercombination and forbidden lines for He-like titanium. Cascades and the effect of resonances for these lines are not considered in this paper. These results are used to fit an experimental soft x-ray spectrum from the PDX (Poloidal Divertor Experiment) tokamak discharge. Good agreement is obtained between computed and observed spectra.

  15. In-Situ XPS Monitoring and Characterization of Electrochemically Prepared Au Nanoparticles in an Ionic Liquid

    PubMed Central

    2017-01-01

    Gold nanoparticles (Au NPs) have been electrochemically prepared in situ and in vacuo using two different electrochemical device configurations, containing an ionic liquid (IL), N-N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide, that serves both as reaction and as stabilizing media for the NPs. It was observed in both devices that Au NPs were created using an anodically triggered route. The created Au NPs are relatively small (3–7 nm) and reside within the IL medium. X-ray photoelectron spectroscopy is utilized to follow not only the formation of the NPs but also their charging/discharging properties, by monitoring the charging shifts of the Au4f peak representing the electrodes and also the Au NPs as well as the F1s peak of the IL after polarizing one of the electrodes. Accordingly, DC polarization across the electrodes leads to a uniform binding energy shift of F1s of the IL along with that of Au4f of the NPs within. Moreover, this shift corresponds to only half of the applied potential. AC polarization brings out another dimension for demonstrating further the harmony between the charging/discharging property of the IL medium and the Au NPs in temporally and laterally resolved fashions. Polarization of the electrodes result in perfect spectral separation of the Au4f peaks of the NPs from those of the metal in both static (DC) and in time- and position-dependent (AC) modes. PMID:28261688

  16. LB1's virtual endocast, microcephaly, and hominin brain evolution.

    PubMed

    Falk, Dean; Hildebolt, Charles; Smith, Kirk; Morwood, M J; Sutikna, Thomas; Jatmiko; Wayhu Saptomo, E; Prior, Fred

    2009-11-01

    Earlier observations of the virtual endocast of LB1, the type specimen for Homo floresiensis, are reviewed, extended, and interpreted. Seven derived features of LB1's cerebral cortex are detailed: a caudally-positioned occipital lobe, lack of a rostrally-located lunate sulcus, a caudally-expanded temporal lobe, advanced morphology of the lateral prefrontal cortex, shape of the rostral prefrontal cortex, enlarged gyri in the frontopolar region, and an expanded orbitofrontal cortex. These features indicate that LB1's brain was globally reorganized despite its ape-sized cranial capacity (417cm(3)). Neurological reorganization may thus form the basis for the cognitive abilities attributed to H. floresiensis. Because of its tiny cranial capacity, some workers think that LB1 represents a Homo sapiens individual that was afflicted with microcephaly, or some other pathology, rather than a new species of hominin. We respond to concerns about our earlier study of microcephalics compared with normal individuals, and reaffirm that LB1 did not suffer from this pathology. The intense controversy about LB1 reflects an older continuing dispute about the relative evolutionary importance of brain size versus neurological reorganization. LB1 may help resolve this debate and illuminate constraints that governed hominin brain evolution.

  17. Evidence of ϒ (1 S )→J /ψ +χc 1 and search for double-charmonium production in ϒ (1 S ) and ϒ (2 S ) decays

    NASA Astrophysics Data System (ADS)

    Yang, S. D.; Shen, C. P.; Ban, Y.; Abdesselam, A.; Adachi, I.; Aihara, H.; Al Said, S.; Arinstein, K.; Asner, D. M.; Aulchenko, V.; Aushev, T.; Ayad, R.; Bakich, A. M.; Bansal, V.; Behera, P.; Bhuyan, B.; Bobrov, A.; Bozek, A.; Bračko, M.; Browder, T. E.; Červenkov, D.; Chekelian, V.; Chen, A.; Cheon, B. G.; Chilikin, K.; Chistov, R.; Cho, K.; Chobanova, V.; Choi, S.-K.; Choi, Y.; Cinabro, D.; Dalseno, J.; Danilov, M.; Dingfelder, J.; Doležal, Z.; Drásal, Z.; Drutskoy, A.; Dutta, K.; Eidelman, S.; Farhat, H.; Fast, J. E.; Ferber, T.; Gaur, V.; Gabyshev, N.; Ganguly, S.; Garmash, A.; Gillard, R.; Goh, Y. M.; Golob, B.; Haba, J.; Hara, T.; Hayasaka, K.; Hayashii, H.; He, X. H.; Hou, W.-S.; Huschle, M.; Iijima, T.; Inami, K.; Ishikawa, A.; Itoh, R.; Jaegle, I.; Joffe, D.; Joo, K. K.; Julius, T.; Kawasaki, T.; Kim, D. Y.; Kim, H. J.; Kim, J. B.; Kim, J. H.; Kim, K. T.; Kinoshita, K.; Ko, B. R.; Kodyš, P.; Korpar, S.; Križan, P.; Krokovny, P.; Kuzmin, A.; Kwon, Y.-J.; Lange, J. S.; Li, J.; Li, Y.; Li Gioi, L.; Libby, J.; Liventsev, D.; Lukin, P.; Miyabayashi, K.; Miyata, H.; Moll, A.; Mussa, R.; Nakano, E.; Nakao, M.; Nanut, T.; Nisar, N. K.; Nishida, S.; Okuno, S.; Ostrowicz, W.; Park, C. W.; Park, H.; Pedlar, T. K.; Pestotnik, R.; Petrič, M.; Piilonen, L. E.; Ribežl, E.; Ritter, M.; Rostomyan, A.; Sakai, Y.; Sandilya, S.; Santelj, L.; Sanuki, T.; Schneider, O.; Schnell, G.; Schwanda, C.; Semmler, D.; Senyo, K.; Shebalin, V.; Shibata, T.-A.; Shiu, J.-G.; Shwartz, B.; Sibidanov, A.; Simon, F.; Sohn, Y.-S.; Sokolov, A.; Starič, M.; Steder, M.; Sumiyoshi, T.; Tamponi, U.; Tanida, K.; Tatishvili, G.; Teramoto, Y.; Uchida, M.; Uehara, S.; Uglov, T.; Unno, Y.; Uno, S.; Urquijo, P.; Usov, Y.; Vahsen, S. E.; Van Hulse, C.; Vanhoefer, P.; Varner, G.; Vinokurova, A.; Vorobyev, V.; Vossen, A.; Wagner, M. N.; Wang, C. H.; Wang, M.-Z.; Wang, P.; Wang, X. L.; Watanabe, M.; Watanabe, Y.; Won, E.; Yamaoka, J.; Yashchenko, S.; Yook, Y.; Yuan, C. Z.; Zhang, Z. P.; Zhilich, V.; Zhulanov, V.; Belle Collaboration

    2014-12-01

    Using data samples of 102 ×106 ϒ (1 S ) and 158 ×106 ϒ (2 S ) events collected with the Belle detector, a first experimental search has been made for double-charmonium production in the exclusive decays ϒ (1 S ,2 S )→J /ψ (ψ')+X , where X =ηc, χc J(J =0 ,1 ,2 ), ηc(2 S ), X (3940 ), and X (4160 ). No significant signal is observed in the spectra of the mass recoiling against the reconstructed J /ψ or ψ' except for the evidence of χc 1 production with a significance of 4.6 σ for ϒ (1 S )→J /ψ +χc 1 . The measured branching fraction B (ϒ (1 S )→J /ψ +χc 1) is [3.90 ±1.21 (stat)±0.23 (syst)]×10-6 . The 90% C.L. upper limits on the branching fractions of the other modes having a significance of less than 3 σ are determined. These results are consistent with theoretical calculations using the nonrelativistic QCD factorization approach.

  18. Catalogue of representative meteor spectra

    NASA Astrophysics Data System (ADS)

    Vojáček, V.; Borovička, J.; Koten, P.; Spurný, P.; Štork, R.

    2016-01-01

    We present a library of low-resolution meteor spectra that includes sporadic meteors, members of minor meteor showers, and major meteor showers. These meteors are in the magnitude range from +2 to -3, corresponding to meteoroid sizes from 1 mm to10 mm. This catalogue is available online at the CDS for those interested in video meteor spectra.

  19. Projecting Spectra for Classroom Investigations.

    ERIC Educational Resources Information Center

    Sadler, Philip

    1991-01-01

    Describes an inexpensive spectrum projector that makes high-dispersion, high-efficiency diffraction gratings using a holographic process. Discusses classroom applications such as transmission spectra, absorption spectra, reflection characteristics of materials, color mixing, florescence and phosphorescence, and break up spectral colors. (MDH)

  20. Investigation of x-ray photoelectron spectroscopic (XPS), cyclic voltammetric analyses of WO3 films and their electrochromic response in FTO/WO3/electrolyte/FTO cells

    NASA Astrophysics Data System (ADS)

    Sivakumar, R.; Gopalakrishnan, R.; Jayachandran, M.; Sanjeeviraja, C.

    2006-06-01

    Electrochromic thin films of tungsten oxide (WO3) were prepared on transparent conducting oxide substrates, i.e., fluorine doped tin oxide coated (FTO or SnO2:F) glass and microscopic glass substrates by the electron beam evaporation technique using pure WO3 (99.99%) pellets at various substrate temperatures (i.e., Tsub = room temperature (RT, 30 °C), 100 °C and 200 °C). The films were prepared under vacuum of the order of 1 × 10-5 mbar. The room temperature prepared films were further post-heat-treated (Tanne) at 200 and 300 °C for about 1 h in the vacuum environment. The prepared films are in monoclinic phase. The chemical composition has been characterized by using the XPS technique. The W 4f and O 1s core levels of WO3 films have been studied on the samples. The obtained core level binding energies revealed the WO3 films contained six-valent tungsten (W6+). The electrochemical nature of the films was studied by a three-electrode electrochemical cell in the configuration of FTO/WO3/H2SO4/Pt, SCE, using the cyclic voltammetry (CV) technique. Electrochromic devices (ECDs) of the general type FTO/WO3/electrolyte/FTO were studied. The films produced at higher substrate temperature show smaller modulation of the visible spectrum, compared with the films produced at lower temperatures. The significant chemical bonding nature associated with the coloring/bleaching process which follows the H+ ion incorporation in the film is studied by FTIR analysis. The W-O-W framework peak was observed at 563 cm-1 and confirms the stability of the films in the electrochemical analysis. The results obtained from cyclic voltammetry technique and ECD cell characterization are used to emphasize the suitability for some applications of the solar control systems.

  1. Ambient Pressure XPS Study of Mixed Conducting Perovskite-Type SOFC Cathode and Anode Materials under Well-Defined Electrochemical Polarization

    PubMed Central

    2015-01-01

    The oxygen exchange activity of mixed conducting oxide surfaces has been widely investigated, but a detailed understanding of the corresponding reaction mechanisms and the rate-limiting steps is largely still missing. Combined in situ investigation of electrochemically polarized model electrode surfaces under realistic temperature and pressure conditions by near-ambient pressure (NAP) XPS and impedance spectroscopy enables very surface-sensitive chemical analysis and may detect species that are involved in the rate-limiting step. In the present study, acceptor-doped perovskite-type La0.6Sr0.4CoO3-δ (LSC), La0.6Sr0.4FeO3-δ (LSF), and SrTi0.7Fe0.3O3-δ (STF) thin film model electrodes were investigated under well-defined electrochemical polarization as cathodes in oxidizing (O2) and as anodes in reducing (H2/H2O) atmospheres. In oxidizing atmosphere all materials exhibit additional surface species of strontium and oxygen. The polaron-type electronic conduction mechanism of LSF and STF and the metal-like mechanism of LSC are reflected by distinct differences in the valence band spectra. Switching between oxidizing and reducing atmosphere as well as electrochemical polarization cause reversible shifts in the measured binding energy. This can be correlated to a Fermi level shift due to variations in the chemical potential of oxygen. Changes of oxidation states were detected on Fe, which appears as FeIII in oxidizing atmosphere and as mixed FeII/III in H2/H2O. Cathodic polarization in reducing atmosphere leads to the reversible formation of a catalytically active Fe0 phase. PMID:26877827

  2. Acid-Base Interactions of Polystyrene Sulfonic Acid in Amorphous Solid Dispersions Using a Combined UV/FTIR/XPS/ssNMR Study.

    PubMed

    Song, Yang; Zemlyanov, Dmitry; Chen, Xin; Nie, Haichen; Su, Ziyang; Fang, Ke; Yang, Xinghao; Smith, Daniel; Byrn, Stephen; Lubach, Joseph W

    2016-02-01

    This study investigates the potential drug-excipient interactions of polystyrene sulfonic acid (PSSA) and two weakly basic anticancer drugs, lapatinib (LB) and gefitinib (GB), in amorphous solid dispersions. Based on the strong acidity of the sulfonic acid functional group, PSSA was hypothesized to exhibit specific intermolecular acid-base interactions with both model basic drugs. Ultraviolet (UV) spectroscopy identified red shifts, which correlated well with the color change observed in lapatinib-PSSA solutions. Fourier transform infrared (FTIR) spectra suggest the protonation of the quinazoline nitrogen atom in both model compounds, which agrees well with data from the crystalline ditosylate salt of lapatinib. X-ray photoelectron spectroscopy (XPS) detected increases in binding energy of the basic nitrogen atoms in both lapatinib and gefitinib, strongly indicating protonation of these nitrogen atoms. (15)N solid-state NMR spectroscopy provided direct spectroscopic evidence for protonation of the quinazoline nitrogen atoms in both LB and GB, as well as the secondary amine nitrogen atom in LB and the tertiary amine nitrogen atom in GB. The observed chemical shifts in the LB-PSSA (15)N spectrum also agree very well with the lapatinib ditosylate salt where proton transfer is known. Additionally, the dissolution and physical stability behaviors of both amorphous solid dispersions were examined. PSSA was found to significantly improve the dissolution of LB and GB and effectively inhibit the crystallization of LB and GB under accelerated storage conditions due to the beneficial strong intermolecular acid-base interaction between the sulfonic acid groups and basic nitrogen centers.

  3. Ambient Pressure XPS Study of Mixed Conducting Perovskite-Type SOFC Cathode and Anode Materials under Well-Defined Electrochemical Polarization.

    PubMed

    Nenning, Andreas; Opitz, Alexander K; Rameshan, Christoph; Rameshan, Raffael; Blume, Raoul; Hävecker, Michael; Knop-Gericke, Axel; Rupprechter, Günther; Klötzer, Bernhard; Fleig, Jürgen

    2016-01-28

    The oxygen exchange activity of mixed conducting oxide surfaces has been widely investigated, but a detailed understanding of the corresponding reaction mechanisms and the rate-limiting steps is largely still missing. Combined in situ investigation of electrochemically polarized model electrode surfaces under realistic temperature and pressure conditions by near-ambient pressure (NAP) XPS and impedance spectroscopy enables very surface-sensitive chemical analysis and may detect species that are involved in the rate-limiting step. In the present study, acceptor-doped perovskite-type La0.6Sr0.4CoO3-δ (LSC), La0.6Sr0.4FeO3-δ (LSF), and SrTi0.7Fe0.3O3-δ (STF) thin film model electrodes were investigated under well-defined electrochemical polarization as cathodes in oxidizing (O2) and as anodes in reducing (H2/H2O) atmospheres. In oxidizing atmosphere all materials exhibit additional surface species of strontium and oxygen. The polaron-type electronic conduction mechanism of LSF and STF and the metal-like mechanism of LSC are reflected by distinct differences in the valence band spectra. Switching between oxidizing and reducing atmosphere as well as electrochemical polarization cause reversible shifts in the measured binding energy. This can be correlated to a Fermi level shift due to variations in the chemical potential of oxygen. Changes of oxidation states were detected on Fe, which appears as Fe(III) in oxidizing atmosphere and as mixed Fe(II/III) in H2/H2O. Cathodic polarization in reducing atmosphere leads to the reversible formation of a catalytically active Fe(0) phase.

  4. Measurement of the muonium 1S-2S transition frequency

    SciTech Connect

    Jungmann, K.; Baird, P.E.G.; Barr, J.R.M.; Berkeland, D.; Boshier, M.G.; Braun, B.; Eaton, G.H.; Ferguson, A.I.; Geerds, H.; Hughes, V.W.; Maas, F.; Matthias, B.E.; Matousek, P.; Persaud, M.; zu Putlitz, G.; Reinhard, I.; Riis, E.; Sandars, P.G.H.; Schwarz, W.; Toner, W.T.; Towrie, M.; Willmann, L.; Woodle, K.A.; Woodman, G.

    1995-04-01

    Resonant ionization spectroscopy has been employed for measuring the 1{sup 2}{ital S}{sub 1/2}{minus}2{sup 2}{ital S}{sub 1/2} frequency difference in the hydrogen-like muonium atom to 2 455 529 002(33)(46) MHz. The 1S-2S two-photon transition was induced Doppler-free using two counter-propagating laser beams. The 2S state was photo-ionized by a third photon from the same laser field. The measurement agrees with QED theory within two standard deviations. The mass of the positive muon can be extracted from the isotope shifts in this transition to hydrogen and deuterium to 105.658 80(29)(43) MeV/c{sup 2}. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}

  5. Measurement of the muonium 1S-2S transition frequency

    SciTech Connect

    Jungmann, K.; Baird, P. E. G.; Barr, J. R. M.; Berkeland, D.; Boshier, M. G.; Braun, B.; Eaton, G. H.; Ferguson, A. I.; Geerds, H.; Hughes, V. W.; Maas, F.; Matthias, B. E.; Matousek, P.; Persaud, M.; Putlitz, G. zu; Reinhard, I.; Riis, E.; Sandars, P. G. H.; Schwarz, W.; Toner, W. T.

    1995-04-01

    Resonant ionization spectroscopy has been employed for measuring the 1{sup 2}S1/2-2{sup 2}S1/2 frequency difference in the hydrogen-like muonium atom to 2 455 529 002(33)(46) MHz. The 1S-2S two-photon transition was induced Doppler-free using two counter-propagating laser beams. The 2S state was photo-ionized by a third photon from the same laser field. The measurement agrees with QED theory within two standard deviations. The mass of the positive muon can be extracted from the isotope shifts in this transition to hydrogen and deuterium to 105.658 80(29)(43) MeV/c{sup 2}.

  6. Homolytic halogenation of 2-alkoxy-1, s-dioxacycloalkanes

    SciTech Connect

    Rol'nik, L.Z.; Pastushenko, E.V.; Rakmankulov, D.L.; Zlot-skii, S.S.

    1984-04-10

    This article examines the free-radical reactions of 2-alkoxy-1, 3-dioxacycloalkanes in the presence of polyhalomethanes. The influence of halogenation agents on the course of the process is studied for the case of 2-(hexyloxy)-1, 3-dioxolane with the use of CBrCl/sub 3/ and CCl/sub 4/. The infrared spectra of the compounds obtained were determined with a UR-20 spectrometer in the range 700-4000 cm/sup -1/ on capillary layers between NaCl plates. The results indicate that the main products of the free-radical transformations of 2-alkoxy-1, 3-dioxacycloalkanes in a medium of CHBr/sub 3/ are alkyl bromoalkyl carbonates, bromoalkyl formates, and aldehydes. It is concluded that the free-radical transformations of cyclic ortho esters in polyhalomethane media initiated by benzoyl peroxide go by an unbranched-chain mechanism.

  7. Phonon spectra of alkali metals

    NASA Astrophysics Data System (ADS)

    Zeković, S.; Vukajlović, F.; Veljković, V.

    1982-10-01

    In this work we used a simple local model pseudopotential which includes screening for the phonon spectra calculations of alkali metals. The results obtained are in very good agreement with experimental data. In some branches of phonon spectra the differences between theoretical and experimental results are within 1-2%, while the maximum error is about 6%. The suggested form of the pseudopotential allows us to describe the phonon spectra of Na, K and Rb with only one, and, at the same time, a unique, parameter. In this case, the maximum disagreements from experiment are 9% for Na, 8% for K and 7% for Rb.

  8. XPS depth profiling of derivatized amine and anhydride plasma polymers: Evidence of limitations of the derivatization approach

    NASA Astrophysics Data System (ADS)

    Manakhov, Anton; Michlíček, Miroslav; Felten, Alexandre; Pireaux, Jean-Jacques; Nečas, David; Zajíčková, Lenka

    2017-02-01

    The quantitative analysis of the chemistry at the surface of functional plasma polymers is highly important for the optimization of their deposition conditions and, therefore, for their subsequent applications. The chemical derivatization of amine and carboxyl-anhydride layers is a well-known technique already applied by many researchers, notwithstanding the known drawback of the derivatization procedures like side or uncomplete reactions that could lead to "unreliable" results. In this work, X-ray photoelectron spectroscopy (XPS) combined with depth profiling with argon clusters is applied for the first time to study derivatized amine and carboxyl-anhydride plasma polymer layers. It revealed an additional important parameter affecting the derivatization reliability, namely the permeation of the derivatizing molecule through the target analysed layer, i.e. the composite effect of the probe molecule size and the layer porosity. Amine-rich films prepared by RF low pressure plasma polymerization of cyclopropylamine were derivatized with trifluoromethyl benzaldehide (TFBA) and it was observed by that the XPS-determined NH2 concentration depth profile is rapidly decreasing over top ten nanometers of the layer. The anhydride-rich films prepared by atmospheric plasma co-polymerization of maleic anhydride and C2H2 have been reacted with, parafluoroaniline and trifluoroethyl amine. The decrease of the F signal in top surface layer of the anhydride films derivatized by the "large" parafluoroaniline was observed similarly as for the amine films but the derivatization with the smaller trifluoroethylamine (TFEA) led to a more homogenous depth profile. The data analysis suggests that the size of the derivatizing molecule is the main factor, showing that the very limited permeation of the TFBA molecule can lead to underestimated densities of primary amines if the XPS analysis is solely carried out at a low take-off angle. In contrast, TFEA is found to be an efficient

  9. [Quantitative surface analysis of Pt-Co, Cu-Au and Cu-Ag alloy films by XPS and AES].

    PubMed

    Li, Lian-Zhong; Zhuo, Shang-Jun; Shen, Ru-Xiang; Qian, Rong; Gao, Jie

    2013-11-01

    In order to improve the quantitative analysis accuracy of AES, We associated XPS with AES and studied the method to reduce the error of AES quantitative analysis, selected Pt-Co, Cu-Au and Cu-Ag binary alloy thin-films as the samples, used XPS to correct AES quantitative analysis results by changing the auger sensitivity factors to make their quantitative analysis results more similar. Then we verified the accuracy of the quantitative analysis of AES when using the revised sensitivity factors by other samples with different composition ratio, and the results showed that the corrected relative sensitivity factors can reduce the error in quantitative analysis of AES to less than 10%. Peak defining is difficult in the form of the integral spectrum of AES analysis since choosing the starting point and ending point when determining the characteristic auger peak intensity area with great uncertainty, and to make analysis easier, we also processed data in the form of the differential spectrum, made quantitative analysis on the basis of peak to peak height instead of peak area, corrected the relative sensitivity factors, and verified the accuracy of quantitative analysis by the other samples with different composition ratio. The result showed that the analytical error in quantitative analysis of AES reduced to less than 9%. It showed that the accuracy of AES quantitative analysis can be highly improved by the way of associating XPS with AES to correct the auger sensitivity factors since the matrix effects are taken into account. Good consistency was presented, proving the feasibility of this method.

  10. Solar Ion Processing of Major Element Surface Compositions of Mature Mare Soils: Insights from Combined XPS and Analytical TEM Observations

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Dukes, C.; Keller, L. P.; Baragiola, R.

    2012-01-01

    Solar wind ions are capable of altering the sur-face chemistry of the lunar regolith by a number of mechanisms including preferential sputtering, radiation-enhanced diffusion and sputter erosion of space weathered surfaces containing pre-existing compositional profiles. We have previously reported in-situ ion irradiation experiments supported by X-ray photoelectron spectroscopy (XPS) and analytical TEM that show how solar ions potentially drive Fe and Ti reduction at the monolayer scale as well as the 10-100 nm depth scale in lunar soils [1]. Here we report experimental data on the effect of ion irradiation on the major element surface composition in a mature mare soil.

  11. IR, NMR, XPS study of 1-( D-3-mercapto-2-methylpropionyl)- L-proline and its zinc complexes

    NASA Astrophysics Data System (ADS)

    Atzei, D.; De Filippo, D.; Rossi, A.; Lai, A.; Saba, G.; Bucci, R.

    1992-07-01

    Two Zn(II) complexes of captopril were prepared and characterized with different analytical methods: IR, NMR and XPS. Captopril is a molecule which has been proven to be very effective in reducing blood pressure. The ligand chelates via the OCO group to a zinc ion and via S and amidic oxygen atoms to another zinc ion when the ZnL complex is obtained. The sulphur atom and the amidic CO group are the only atoms involved in the coordination when the sodium—zinc complex, Na 2ZnL 2, is synthesized.

  12. Raman and XPS characterization of fuel-cladding interactions using miniature specimens

    SciTech Connect

    Windisch, Charles F.; Henager, Charles H.; Engelhard, Mark H.; Bennett, Wendy D.

    2009-01-01

    Laser Raman spectroscopy was evaluated as a tool for studying fuel-cladding chemical interactions at elevated temperatures. Materials and conditions were selected to simulate the interface of oxide fuels and fission products with high-temperature cladding materials for TRU-MOX fueled reactors. Both ex-situ and in-situ spectroscopy measurements were performed using polished HT-9 disks, uncoated and coated with yttria-stabilized zirconia, that were exposed to air oxidation at temperatures between 873-973K. Ex-situ measurements (under ambient conditions) were conducted to identify oxide phases, determine oxidation mechanisms and approximate film growth rates with an optimal signal-to-noise for the equipment used. Subsequently performed in-situ measurements were used to evaluate the sensitivity of the technique for measurements at elevated temperature in a hot-stage. Raman spectra were supported with x-ray photoelectron spectroscopy depth profiling. The results, which are for non-fueled materials in this study, illustrated a method for fast screening of candidate alloys with actinide-based MOX fuel mixtures.

  13. Spectra ID of recent SN

    NASA Astrophysics Data System (ADS)

    Challis, Peter

    2013-12-01

    P. Challis, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, report spectra (range 320-860 nm) of various SN obtained during Dec. 24-27 UT by P. Challis, S. Gottilla (MMTO.org), and E. Marin (MMTO.org) with the MMT 6.5-m telescope (+ Blue Channel). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J.

  14. Understanding Chemical versus Electrostatic Shifts in X-ray Photoelectron Spectra of Organic Self-Assembled Monolayers

    PubMed Central

    2016-01-01

    The focus of the present article is on understanding the insight that X-ray photoelectron spectroscopy (XPS) measurements can provide when studying self-assembled monolayers. Comparing density functional theory calculations to experimental data on deliberately chosen model systems, we show that both the chemical environment and electrostatic effects arising from a superposition of molecular dipoles influence the measured core-level binding energies to a significant degree. The crucial role of the often overlooked electrostatic effects in polar self-assembled monolayers (SAMs) is unambiguously demonstrated by changing the dipole density through varying the SAM coverage. As a consequence of this effect, care has to be taken when extracting chemical information from the XP spectra of ordered organic adsorbate layers. Our results, furthermore, imply that XPS is a powerful tool for probing local variations in the electrostatic energy in nanoscopic systems, especially in SAMs. PMID:26937264

  15. Structural model of homogeneous As–S glasses derived from Raman spectroscopy and high-resolution XPS

    SciTech Connect

    Golovchak, R.; Shpotyuk, O.; Mccloy, J. S.; Riley, B. J.; Windisch, C. F.; Sundaram, S. K.; Kovalskiy, A.; Jain, H.

    2010-11-28

    The structure of homogeneous bulk As x S100- x (25 ≤ x ≤ 42) glasses, prepared by the conventional rocking–melting–quenching method, was investigated using high-resolution X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. It is shown that the main building blocks of their glass networks are regular AsS3/2 pyramids and sulfur chains. In the S-rich domain, the existence of quasi-tetrahedral (QT) S = As(S1/2)3 units is deduced from XPS data, but with a concentration not exceeding ~3–5% of total atomic sites. Therefore, QT units do not appear as primary building blocks of the glass backbone in these materials, and an optimally-constrained network may not be an appropriate description for glasses when x < 40. Finally, it is shown that, in contrast to Se-based glasses, the ‘chain-crossing’ model is only partially applicable to sulfide glasses.

  16. An AFM, XPS and wettability study of the surface heterogeneity of PS/PMMA-r-PMAA demixed thin films.

    PubMed

    Zuyderhoff, Emilienne M; Dekeyser, Caroline M; Rouxhet, Paul G; Dupont-Gillain, Christine C

    2008-03-01

    A series of homopolymer/random copolymer blends was used to produce heterogeneous surfaces by demixing in thin films. The chosen homopolymer is polystyrene (PS) and the random copolymer is poly(methyl methacrylate)-r-poly(methacrylic acid) (PMMA-r-PMAA), whose acidic functions could be used as reactive sites in view of further surface functionalization. The proportion of each polymer at the interface was deduced from X-ray photoelectron spectroscopy (XPS) data using, on the one hand, the O/C ratio, and on the other hand, decomposition of the carbon peak of the blends in two components corresponding to the carbon peaks of PS and PMMA-r-PMAA. Combining the information from XPS with atomic force microscopy (AFM) images, water contact angle measurements and PS selective dissolution, it appears that the surfaces obtained from blends with a high PS content (90/10 to 70/30) display pits with a bottom made of PMMA-r-PMAA, randomly distributed in a PS matrix. On the other hand, the surfaces obtained from blends with a low PS content (30/70 to 10/90) display randomly distributed PS islands surrounded by a PMMA-r-PMAA matrix. The characteristics of the heterogeneous films are thought to be governed by the higher affinity of PMMA-r-PMAA for the solvent (dioxane), which leads to the elevation of the PS phase compared to the PMMA-r-PMAA phase, and to surface enrichment in PMMA-r-PMAA.

  17. Duplex Oxide Formation during Transient Oxidation of Cu-5%Ni(001) Investigated by In situ UHV-TEM and XPS

    SciTech Connect

    Yang, J.C.; Starr, D.; Kang, Y.; Luo, L.; Tong, X.; Zhou, G.

    2012-05-20

    The transient oxidation stage of a model metal alloy thin film was characterized with in situ ultra-high vacuum (UHV) transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and analytic high-resolution TEM. We observed the formations of nanosized NiO and Cu{sub 2}O islands when Cu-5a5%Ni(100) was exposed to oxygen partial pressure, pO{sub 2} = 1 x 10{sup -4} Torr and various temperatures in situ. At 350 C epitaxial Cu{sub 2}O islands formed initially and then NiO islands appeared on the surface of the Cu{sub 2}O island, whereas at 750 C NiO appeared first. XPS and TEM was used to reveal a sequential formation of NiO and then Cu{sub 2}O islands at 550 C. The temperature-dependant oxide selection may be due to an increase of the diffusivity of Ni in Cu with increasing temperature.

  18. Core-level spectra and molecular deformation in adsorption: V-shaped pentacene on Al(001)

    PubMed Central

    Lin, He; Brivio, Gian Paolo; Floreano, Luca; Fratesi, Guido

    2015-01-01

    Summary By first-principle simulations we study the effects of molecular deformation on the electronic and spectroscopic properties as it occurs for pentacene adsorbed on the most stable site of Al(001). The rationale for the particular V-shaped deformed structure is discussed and understood. The molecule–surface bond is made evident by mapping the charge redistribution. Upon X-ray photoelectron spectroscopy (XPS) from the molecule, the bond with the surface is destabilized by the electron density rearrangement to screen the core hole. This destabilization depends on the ionized carbon atom, inducing a narrowing of the XPS spectrum with respect to the molecules adsorbed hypothetically undistorted, in full agreement to experiments. When looking instead at the near-edge X-ray absorption fine structure (NEXAFS) spectra, individual contributions from the non-equivalent C atoms provide evidence of the molecular orbital filling, hybridization, and interchange induced by distortion. The alteration of the C–C bond lengths due to the V-shaped bending decreases by a factor of two the azimuthal dichroism of NEXAFS spectra, i.e., the energy splitting of the sigma resonances measured along the two in-plane molecular axes. PMID:26734516

  19. Functional group analysis of natural organic colloids and clay association kinetics using C(1s) spectromicroscopy

    NASA Astrophysics Data System (ADS)

    Schäfer, T.; Hertkorn, N.; Artinger, R.; Claret, F.; Bauer, A.

    2003-03-01

    The quantification of natural humic colloid functional group content and chemical association of humic substances with clay minerals exerts a crucial role in the colloid-borne mobility of actinides due to the functional group dependent strong interaction with multivalent metal ions. Functional group quantification in isolated fulvic acids of the Gorleben groundwater (Lower Saxony, NW Germany) by comparison of high resolution C(1s) NEXAFS spectra deconvolution with ^{13}C-NMR measurements showed good correlation (r^2> 0.9) and gives a potential quantification tool in complex natural groundwater Systems. Time resolved soft X-ray spectromicroscopy on dissolved organic carbon stabilized SWy-2 smectite colloids revealed an enrichment of carboxyl groups on broken edges (silanol/aluminol groups) at short contact times (1h). With longer contact times (7d, 6 months) the clay associated organic carbon increases and significantly higher aromatic content associated with basal surfaces were detected. The enhanced sorption of aromatic compounds can be related to an increase in mineral surface hydrophobicity and/or preferential sorption on charged siloxane surfaces.

  20. Vibrational Spectra of Selected Monohalogenated Monocarboxylic Acids.

    DTIC Science & Technology

    HALOGENATED HYDROCARBONS, INFRARED SPECTRA), (*CARBOXYLIC ACIDS, *INFRARED SPECTRA), IODINE COMPOUNDS, CHLORINE COMPOUNDS, BROMINE COMPOUNDS, ACETIC ACID , ACETATES, MOLECULAR STRUCTURE, MOLECULAR ASSOCIATION

  1. Photon spectra from WIMP annihilation

    SciTech Connect

    Cembranos, J. A. R.; Cruz-Dombriz, A. de la; Dobado, A.; Maroto, A. L.; Lineros, R. A.

    2011-04-15

    If the present dark matter in the Universe annihilates into standard model particles, it must contribute to the fluxes of cosmic rays that are detected on the Earth and, in particular, to the observed gamma-ray fluxes. The magnitude of such a contribution depends on the particular dark matter candidate, but certain features of the produced photon spectra may be analyzed in a rather model-independent fashion. In this work we provide the complete photon spectra coming from WIMP annihilation into standard model particle-antiparticle pairs obtained by extensive Monte Carlo simulations. We present results for each individual annihilation channel and provide analytical fitting formulas for the different spectra for a wide range of WIMP masses.

  2. QUALITATIVE INTERPRETATION OF GALAXY SPECTRA

    SciTech Connect

    Sanchez Almeida, J.; Morales-Luis, A. B.; Terlevich, R.; Terlevich, E.; Cid Fernandes, R. E-mail: abml@iac.es E-mail: eterlevi@inaoep.mx

    2012-09-10

    We describe a simple step-by-step guide to qualitative interpretation of galaxy spectra. Rather than an alternative to existing automated tools, it is put forward as an instrument for quick-look analysis and for gaining physical insight when interpreting the outputs provided by automated tools. Though the recipe is for general application, it was developed for understanding the nature of the Automatic Spectroscopic K-means-based (ASK) template spectra. They resulted from the classification of all the galaxy spectra in the Sloan Digital Sky Survey data release 7, thus being a comprehensive representation of the galaxy spectra in the local universe. Using the recipe, we give a description of the properties of the gas and the stars that characterize the ASK classes, from those corresponding to passively evolving galaxies, to H II galaxies undergoing a galaxy-wide starburst. The qualitative analysis is found to be in excellent agreement with quantitative analyses of the same spectra. We compare the mean ages of the stellar populations with those inferred using the code STARLIGHT. We also examine the estimated gas-phase metallicity with the metallicities obtained using electron-temperature-based methods. A number of byproducts follow from the analysis. There is a tight correlation between the age of the stellar population and the metallicity of the gas, which is stronger than the correlations between galaxy mass and stellar age, and galaxy mass and gas metallicity. The galaxy spectra are known to follow a one-dimensional sequence, and we identify the luminosity-weighted mean stellar age as the affine parameter that describes the sequence. All ASK classes happen to have a significant fraction of old stars, although spectrum-wise they are outshined by the youngest populations. Old stars are metal-rich or metal-poor depending on whether they reside in passive galaxies or in star-forming galaxies.

  3. The structure of BPS spectra

    NASA Astrophysics Data System (ADS)

    Longhi, Pietro

    In this thesis we develop and apply novel techniques for analyzing BPS spectra of supersymmetric quantum field theories of class S. By a combination of wall-crossing, spectral networks and quiver methods we explore the BPS spectra of higher rank four-dimensional N = 2 super Yang-Mills, uncovering surprising new phenomena. Focusing on the SU(3) case, we prove the existence of wild BPS spectra in field theory, featuring BPS states of higher spin whose degeneracies grow exponentially with the energy. The occurrence of wild BPS states is surprising because it appears to be in tension with physical expectations on the behavior of the entropy as a function of the energy scale. The solution to this puzzle comes from realizing that the size of wild BPS states grows rapidly with their mass, and carefully analyzing the volume-dependence of the entropy of BPS states. We also find some interesting structures underlying wild BPS spectra, such as a Regge-like relation between the maximal spin of a BPS multiplet and the square of its mass, and the existence of a universal asymptotic distribution of spin-j irreps within a multiplet of given charge. We also extend the spectral networks construction by introducing a refinement in the topological classification of 2d-4d BPS states, and identifying their spin with a topological invariant known as the "writhe of soliton paths". A careful analysis of the 2d-4d wall-crossing behavior of this refined data reveals that it is described by motivic Kontsevich-Soibelman transformations, controlled by the Protected Spin Character, a protected deformation of the BPS index encoding the spin of BPS states. Our construction opens the way for the systematic study of refined BPS spectra in class S theories. We apply it to several examples, including ones featuring wild BPS spectra, where we find an interesting relation between spectral networks and certain functional equations. For class S theories of A 1 type, we derive an alternative technique for

  4. Ψ(2 S) Decay to J/Ψ(1 S) + 2 π or J/Ψ(1 S) + σ + 2 π

    NASA Astrophysics Data System (ADS)

    Kisslinger, Leonard S.; Li-juan, Zhou; Wei-xing, Ma; Shen, Pengnian

    2017-03-01

    We estimate the decay rate of the Ψ(2 S) to J/Ψ(1 S) + 2 π and J/Ψ(1 S) + σ + 2 π. This is based on the mixed hybrid theory that was developed for the Ψ(2 S) and was used to estimate the ratio {Ψ }(2S)→ J/{Ψ }(1S) + σ to {Ψ }(2S) → J/{Ψ }(1S) + 2 π in 2011. A main motivation of the present work is to predict the possible experimental detection of the decay of Ψ(2 S) to J/Ψ(1 S) + σ+2 π, or possibly to J/Ψ(1 S)+2 π+glueball.

  5. Determination of electron-impact transfer rate coefficients between argon 1s2 and 1s3 states by laser pump-probe technique

    NASA Astrophysics Data System (ADS)

    Carbone, E. A. D.; Hübner, S.; van der Mullen, J. J. A. M.; Kroesen, G. M. W.; Sadeghi, N.

    2013-10-01

    In a microwave argon plasma, the electron-impact population transfers between the first four excited states of argon are studied by time-resolved laser pump-probe technique. Metastable atoms in the 1s5 state (in Paschen's notation) are selectively pumped up to the 2p3 state, with a nanosecond pulsed dye laser tuned to the 706 nm argon transition and the temporal response of the densities in the 1s3, 1s4 and 1s5 states are monitored by time-resolved laser diode absorption. The electron density and temperature are also measured by Thomson scattering along the plasma column for different pressures. The rate coefficient measured for the 1s3 to 1s2 state transfer, for which only rough estimations exist in the literature is found to be 9 × 10-13 m3 s-1, almost five times larger than the value commonly assumed.

  6. Spectroscopic characterization of iron ores formed in different geological environments using FTIR, XPS, Mössbauer spectroscopy and thermoanalyses

    NASA Astrophysics Data System (ADS)

    Salama, Walid; El Aref, Mourtada; Gaupp, Reinhard

    2015-02-01

    Application of thermoanalyses, FTIR, XPS and Mössbauer spectroscopic methods can differentiate between iron ores formed in different geological environments. Two types of iron ore are formed in shallow marine environments in the Bahariya Depression, Egypt, yellowish brown ooidal ironstones (type 1) and black mud and fossiliferous ironstones (type 2). Both types were subjected to subaerial weathering, producing a dark brown lateritic (pedogenic) iron ore (type 3). Microscopic investigation indicates goethite is the main mineral in types 1 and 3, while hematite is the main mineral in type 2 and also occurs in type 3. Thermoanalyses indicated the dehydroxylation endothermic peak of goethite of type 1 occurs between 329 and 345 °C, while in type 3 occurs between 284 and 330 °C. This variation can be attributed to the nanocrystalline nature of the pedogenic goethite. The presence of an exothermic peak at 754 °C in type 3 is probably attributed to goethite-hematite phase transformation. FTIR spectroscopy indicated that goethite of type 1 is characterized by the presence of the δ-OH band between 799 and 802 cm-1, the γ-OH between 898 and 904 cm-1 and the bulk hydroxyl stretch between 3124 and 3133 cm-1. Goethite of type 3 is characterized by the absence of the bulk hydroxyl stretch band and the δ-OH and γ-OH are shifted to higher Wavenumbers that can attributed to a relative Al-for Fe-substitution. Hematite is identified by two IR bands; the first is between 464 and 475 cm-1 and at the second is between 540 and 557 cm-1. Quartz is identified in all iron ore types, nitrates are identified in types 1 and 2, but absent in type 3 and Kaolinite is identified in type 2. The Mössbauer spectrum of type 1 is fitted with one magnetic sextet corresponding to goethite with an isomer shift (IS) = 0.374 mm s-1, a quadruple splitting (QS) = -0.27 mm s-1 and a hyperfine magnetic field (BHF) = ∼37. The Mössbauer spectrum of type 2 is fitted with one magnetic sextet

  7. XPS study of the chemical stability of DyBa2Cu3O6+δ superconductor

    NASA Astrophysics Data System (ADS)

    Fetisov, A. V.; Kozhina, G. А.; Estemirova, S. Kh.; Fetisov, V. B.; Gulyaeva, R. I.

    2015-01-01

    The chemical stability of the powder DyBa2Cu3O6+δ has been studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and thermal analysis at ambient conditions. The powder was subjected to mechanical processing in a ball mill-activator to accelerate chemical degradation. The kinetic regularities of hydrolytic decomposition of DyBa2Cu3O6+δ under the influence of air moisture have been determined. The resistive properties of DyBa2Cu3O6+δ to water have been found to be better, but not much different from analogous properties of YBa2Cu3O6+δ which is unstable in a wet environment. Chemical degradation of the material is triggered by crucial concentrating of water particles near the free surface of the solid reactant (due to their low diffusibility in the bulk) leading to rapid chemical decomposition of the respective regions.

  8. Electronic structure of Ar+ ion-sputtered thin-film MoS2: A XPS and IPES study

    NASA Astrophysics Data System (ADS)

    Santoni, Antonino; Rondino, Flaminia; Malerba, Claudia; Valentini, Matteo; Mittiga, Alberto

    2017-01-01

    Polycrystalline MoS2 grown by Mo sulphurization was exposed to increasing doses of Ar+ ions at 250 eV starting from 2.2 × 1015 ions/cm2 to 3.92 × 1017 ions/cm2. Electronic structure changes were monitored by X-Ray Photoelectron Spectroscopy (XPS) and Inverse Photolectron Spectroscopy (IPES). No change in the Fermi level position was observed with Ar+ dosing. Ion bombardment resulted in a new visible feature at lower binding energy in the Mo3d core level, while the S2p lineshape showed little changes. The formation of a steady state from 2.49 × 1017 ions/cm2 has been detected. The investigation of the occupied and unoccupied states on the steady-state surface pointed to the simultaneous presence of metallic-like Mo with amorphous MoS2-x.

  9. Surface chemical composition of human maxillary first premolar as assessed by X-ray photoelectron spectroscopy (XPS)

    NASA Astrophysics Data System (ADS)

    Lou, Leo; Nelson, Alan E.; Heo, Giseon; Major, Paul W.

    2008-08-01

    The surface chemical composition of dental enamel has been postulated as a contributing factor in the variation of bond strength of brackets bonded to teeth, and hence, the probability of bracket failure during orthodontic treatment. This study systematically investigated the chemical composition of 98 bonding surfaces of human maxillary premolars using X-ray photoelectron spectroscopy (XPS) to ascertain compositional differences between right and left first premolars. The major elements detected in all samples were calcium, phosphorus, oxygen, nitrogen and carbon. Surface compositions were highly variable between samples and several elements were found to be highly correlated. No statistical significant difference in the chemical composition of the maxillary right and left first premolars was found ( p > 0.05). Knowledge of the chemical composition of enamel surfaces will facilitate future studies that relate this information to the variations in dental enamel bond strength.

  10. Multiple Coordination of CO on Molybdenum Nanoparticles: Evidence for Intermediate Mox(CO)y Species by XPS and UPS.

    PubMed

    Jiang, Zhiquan; Huang, Weixin; Zhang, Zhen; Zhao, Hong; Tan, Dali; Bao, Xinhe

    2006-12-28

    CO chemisorption on the metallic molybdenum nanoparticles supported on the thin alumina film was investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). A binary compound of molybdenum and CO is found to be formed on the surface upon CO dose, accompanied with a positive binding energy shift of the Mo 3d doublet and a localized Mo 4d valence band. A loose packing of the metallic molybdenum favors the formation of this intermediate Mox(CO)y species. The formation of the Mox(CO)y species implies that the property of the metallic molybdenum nanoparticles on the thin alumina film is much different from that of the bulk molybdenum, indicating a significant nanometer size effect.

  11. Computer Simulation of NMR Spectra.

    ERIC Educational Resources Information Center

    Ellison, A.

    1983-01-01

    Describes a PASCAL computer program which provides interactive analysis and display of high-resolution nuclear magnetic resonance (NMR) spectra from spin one-half nuclei using a hard-copy or monitor. Includes general and theoretical program descriptions, program capability, and examples of its use. (Source for program/documentation is included.)…

  12. Classical Trajectories and Quantum Spectra

    NASA Technical Reports Server (NTRS)

    Mielnik, Bogdan; Reyes, Marco A.

    1996-01-01

    A classical model of the Schrodinger's wave packet is considered. The problem of finding the energy levels corresponds to a classical manipulation game. It leads to an approximate but non-perturbative method of finding the eigenvalues, exploring the bifurcations of classical trajectories. The role of squeezing turns out decisive in the generation of the discrete spectra.

  13. Discrimination of petroleum fluorescence spectra.

    PubMed

    Stelmaszewski, Adam

    2007-01-01

    This paper presents studies of the total spectra (fluorescence-excitation matrix) of petroleum with regard to the utilization of fluorescence for determining petroleum pollutants. Thorough testing of one group, comprising almost forty lubricating oils in the form of their hexane solutions, points out their discrimination.

  14. Highly efficient removal of heavy metals by polymer-supported nanosized hydrated Fe(III) oxides: behavior and XPS study.

    PubMed

    Pan, Bingjun; Qiu, Hui; Pan, Bingcai; Nie, Guangze; Xiao, Lili; Lv, Lu; Zhang, Weiming; Zhang, Quanxing; Zheng, Shourong

    2010-02-01

    The present study developed a polymer-based hybrid sorbent (HFO-001) for highly efficient removal of heavy metals [e.g., Pb(II), Cd(II), and Cu(II)] by irreversibly impregnating hydrated Fe(III) oxide (HFO) nanoparticles within a cation-exchange resin D-001 (R-SO(3)Na), and revealed the underlying mechanism based on X-ray photoelectron spectroscopy (XPS) study. HFO-001 combines the excellent handling, flow characteristics, and attrition resistance of conventional cation-exchange resins with the specific affinity of HFOs toward heavy metal cations. As compared to D-001, sorption selectivity of HFO-001 toward Pb(II), Cu(II), and Cd(II) was greatly improved from the Ca(II) competition at greater concentration. Column sorption results indicated that the working capacity of HFO-001 was about 4-6 times more than D-001 with respect to removal of three heavy metals from simulated electroplating water (pH approximately 4.0). Also, HFO-001 is particularly effective in removing trace Pb(II) and Cd(II) from simulated natural waters to meet the drinking water standard, with treatment volume orders of magnitude higher than D-001. The superior performance of HFO-001 was attributed to the Donnan membrane effect exerted by the host D-001 as well as to the impregnated HFO nanoparticles of specific interaction toward heavy metal cations, as further confirmed by XPS study on lead sorption. More attractively, the exhausted HFO-001 beads can be effectively regenerated by HCl-NaCl solution (pH 3) for repeated use without any significant capacity loss.

  15. Tracking the conversion of nitrogen during pyrolysis of antibiotic mycelial fermentation residues using XPS and TG-FTIR-MS technology.

    PubMed

    Zhu, Xiangdong; Yang, Shijun; Wang, Liang; Liu, Yuchen; Qian, Feng; Yao, Wenqing; Zhang, Shicheng; Chen, Jianmin

    2016-04-01

    Antibiotic mycelial fermentation residues (AMFRs), which are emerging solid pollutants, have been recognized as hazardous waste in China since 2008. Nitrogen (N), which is an environmental sensitivity element, is largely retained in AMFR samples derived from fermentation substrates. Pyrolysis is a promising technology for the treatment of solid waste. However, the outcomes of N element during the pyrolysis of AMFRs are still unknown. In this study, the conversion of N element during the pyrolysis of AMFRs was tracked using XPS (X-ray photoelectron spectroscopy) and online TG-FTIR-MS (Thermogravimetry-Fourier transform infrared-Mass spectrometry) technology. In the AMFR sample, organic amine-N, pyrrolic-N, protein-N, pyridinic-N, was the main N-containing species. XPS results indicated that pyrrolic-N and pyridinic-N were retained in the AMFR-derived pyrolysis char. More stable species, such as N-oxide and quaternary-N, were also produced in the char. TG-FTIR-MS results indicated that NH3 and HCN were the main gaseous species, and their contents were closely related to the contents of amine-N and protein-N, and pyrrolic-N and pyridinic-N of AMFRs, respectively. Increases in heating rate enhanced the amounts of NH3 and HCN, but had less of an effect on the degradation degree of AMFRs. N-containing organic compounds, including amine-N, nitrile-N and heterocyclic-N, were discerned from the AMFR pyrolysis process. Their release range was extended with increasing of heating rate and carbon content of AMFR sample. This work will help to take appropriate measure to reduce secondary pollution from the treatment of AMFRs.

  16. Shape effects on asteroid spectra

    NASA Astrophysics Data System (ADS)

    Davalos, J.; Carvano, J.

    2014-07-01

    The objective of this work is to probe how the shape of a body like an asteroid could be modifying its observed spectra and the derived mineralogical interfaces based on spectral modeling. To model this effect, we construct an oblate ellipsoid with triangular facets, where each facet contributes to the overall reflectance. The synthetic spectra is generated by the isotropic multiple-scattering approximation (IMSA) reflectance model of Hapke (1993). First, we obtained optical constants by inverting the spectra of meteorites, obtained from the RELAB spectral database. These optical constants were found inverting the reflectance bidirectional equation of Hapke; this is made in two steps: (i) The first inversion is to find the single-scattering albedo π (ii) in the model of Hapke, this albedo is found under the regime of the geometric optics, where the particle size is much larger than the wavelength of the incident radiation. Here we assumed a constant value for the real part of the optical constant n=1.5. With these optical constants, we can construct synthetic spectra for any particle size. The phase function used is the double Henyey-Greenstein phase function and an accurate expression for the H-functions. We started with the ellipsoidal shape a=1.0, b=c=0.5 for two particle size 50 and 250 μ m, in this part, we found good differences in the BAR parameter between the two geometric models, this was done for 100 Eucrite meteorites spectra. In this first study, we found that the BAR parameter between the two models is bigger when the particle size increases. In the second part, we started with different ellipsoidal shapes and produced synthetic spectra for material with eucrite and diogenite composition with a phase angle of 20 degrees, incidence and emission angles of 10 degrees, and particle size at 250 μ m. All spectra was generated for four parameters of phase angle b=[0.2,0.4,0.6,0.8] taking the empirical relation between the phase constants of Hapke (2012

  17. Study of Y(3S, 2S)-> eta Y(1S) and Y(3S, 2S) -> pi pi- Y(1S) Hadronic Transitions

    SciTech Connect

    Lees, J.P.; Poireau, V.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Milanes, D.A.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Brown, D.N.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Koch, H.; Schroeder, T.; Asgeirsson, D.J.; Hearty, C.; Mattison, T.S.; McKenna, J.A.; /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /Indian Inst. Tech., Guwahati /Harvard U. /Harvey Mudd Coll. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Paris U., VI-VII /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /INFN, Naples /Naples U. /NIKHEF, Amsterdam /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Southern Methodist U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas Nuclear Corp., Austin /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U. /Victoria U. /Warwick U. /Wisconsin U., Madison

    2012-03-27

    We study the {Upsilon}(3S, 2S) {yields} {eta}{Upsilon}(1S) and {Upsilon}(3S, 2S) {yields} {pi}{sup +}{pi}{sup -}{Upsilon}(1S) transitions with 122 x 10{sup 6} {Upsilon}(3S) and 100 x 10{sup 6} {Upsilon}(2S) mesons collected by the BABAR detector at the PEP-II asymmetric-energy e{sup +}e{sup -} collider. We measure {Beta}[{Upsilon}(2S) {yields} {eta}{Upsilon}(1S)] = (2.39 {+-} 0.31(stat.) {+-} 0.14(syst.)) x 10{sup -4} and {Lambda}[{Upsilon}(2S) {yields} {eta}{Upsilon}(1S)]/{Lambda}[{Upsilon}(2S) {yields} {pi}{sup +}{pi}{sup -}{Upsilon}(1S)] = (1.35 {+-} 0.17(stat.) {+-} 0.08(syst.)) x 10{sup -3}. We find no evidence for {Upsilon}(3S) {yields} {eta}{Upsilon}(1S) and obtain {Beta}[{Upsilon}(3S) {yields} {eta}{Upsilon}(1S)] < 1.0 x 10{sup -4} and {Lambda}[{Upsilon}(3S) {yields} {eta}{Upsilon}(1S)]/{Lambda}[{Upsilon}(3S) {yields} {pi}{sup +}{pi}{sup -}{Upsilon}(1S)] < 2.3 x 10{sup -3} as upper limits at the 90% confidence level. We also provide improved measurements of the {Upsilon}(2S)-{Upsilon}(1S) and {Upsilon}(3S)-{Upsilon}(1S) mass differences, 562.170 {+-} 0.007(stat.) {+-} 0.088(syst.)MeV/c{sup 2} and 893.813 {+-} 0.015(stat.) {+-} 0.107(syst.)MeV/c{sup 2}, respectively.

  18. pH Dependent Chiroptical Properties of (1R,2R)- and (1S,2S)-trans-Cyclohexane Diesters and Diamides from VCD, ECD, and CPL Spectroscopy.

    PubMed

    Mazzeo, Giuseppe; Abbate, Sergio; Longhi, Giovanna; Castiglioni, Ettore; Boiadjiev, Stefan E; Lightner, David A

    2016-03-10

    Diesters of (1R,2R)- and (1S,2S)-cyclohexanediols and diamides of (1R,2R)- and (1S,2S)-diaminocyclohexane with p-hydroxycinnamic acid have been known for some time to exhibit intense bisignate electronic circular dichroism (ECD) spectra in CH3OH. It was also known that added NaOH causes a bathochromic shift of ∼50 nm in CH3OH, and an even higher one in DMSO. We have measured vibrational circular dichroism (VCD) spectra both for neutral compounds and in the presence of NaOH and other bases. The VCD and IR spectra in the mid-IR region for CD3OD and DMSO-d6 solution exhibit high sensitivity to the charged state for the diesters. They possess two strong bisignate features in the presence of bases in the mid-IR, which are interpreted in terms of vibrational exciton couplets, while this phenomenon is less evident in diamides. VCD allied to density functional theory (DFT) calculations allows one to shed some light on the spectral differences of diesters and diamides by studying their conformational properties. Optical rotatory dispersion (ORD) curves confirm the ECD data. Circularly polarized luminescence (CPL) data have been also acquired, which are rather intense in basified solution: the CPL spectra are monosignate and are as intense in the diester and in the diamide case.

  19. Resonant Inelastic Scattering Spectra of Free Molecules with Vibrational Resolution

    SciTech Connect

    Hennies, Franz; Pietzsch, Annette; Berglund, Martin; Foehlisch, Alexander; Schmitt, Thorsten; Strocov, Vladimir; Karlsson, Hans O.; Andersson, Joakim; Rubensson, Jan-Erik

    2010-05-14

    Inelastic x-ray scattering spectra excited at the 1s{sup -1{pi}}* resonance of gas phase O{sub 2} have been recorded with an overall energy resolution that allows for well-resolved vibrational progressions. The nuclear wave packet dynamics in the intermediate state is reflected in vibrational excitations of the electronic ground state, and by fine-tuning the excitation energy the dissociation dynamics in the predissociative B{sup '} {sup 3{Pi}}{sub g} final state is controlled.

  20. IUEAGN: A database of ultraviolet spectra of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Pike, G.; Edelson, R.; Shull, J. M.; Saken, J.

    1993-01-01

    In 13 years of operation, IUE has gathered approximately 5000 spectra of almost 600 Active Galactic Nuclei (AGN). In order to undertake AGN studies which require large amounts of data, we are consistently reducing this entire archive and creating a homogeneous, easy-to-use database. First, the spectra are extracted using the Optimal extraction algorithm. Continuum fluxes are then measured across predefined bands, and line fluxes are measured with a multi-component fit. These results, along with source information such as redshifts and positions, are placed in the IUEAGN relational database. Analysis algorithms, statistical tests, and plotting packages run within the structure, and this flexible database can accommodate future data when they are released. This archival approach has already been used to survey line and continuum variability in six bright Seyfert 1s and rapid continuum variability in 14 blazars. Among the results that could only be obtained using a large archival study is evidence that blazars show a positive correlation between degree of variability and apparent luminosity, while Seyfert 1s show an anti-correlation. This suggests that beaming dominates the ultraviolet properties for blazars, while thermal emission from an accretion disk dominates for Seyfert 1s. Our future plans include a survey of line ratios in Seyfert 1s, to be fitted with photoionization models to test the models and determine the range of temperatures, densities and ionization parameters. We will also include data from IRAS, Einstein, EXOSAT, and ground-based telescopes to measure multi-wavelength correlations and broadband spectral energy distributions.

  1. L α X-Ray Emission Spectra of Copper Compounds and Alloys

    NASA Astrophysics Data System (ADS)

    Sugiura, Chikara

    1994-05-01

    With a two-crystal vacuum spectrometer equipped with beryl crystals,the Cu Lα emission spectra in fluorescence have been measuredfor selected copper compounds Cu2O, CuO, CuCl, CuBr, CuI,CuF2, CuCl2, CuBr2, CuF2·2H2O,CuCl2·2H2O and Cu3P, and alloysα-Cu+35%Zn and Cu+2%Be. The measured spectra aregrouped into three classes. The first class comprises the spectraof alloys, which consist of a single broad band similar to thatof Cu metal. The second class includes the spectra of monovalentcopper compounds, which are composed of a prominent peak and itshigh- and low-energy structures. To the third class belong thespectra of divalent copper compounds, which consist of a strongpeak accompanied with a characteristic dip and hump on thehigh-energy side. The Cu Lα emission bands of Cu2O,CuCl and CuBr are compared with available XPS spectra andtheoretical Cu-3d-DOS.

  2. Phobos surface spectra mineralogical modeling

    NASA Astrophysics Data System (ADS)

    Pajola, M.; Lazzarin, M.; Dalle Ore, C. M.; Cruikshank, D. P.; Roush, T. L.; Pendleton, Y.; Bertini, I.; Magrin, S.; Carli, C.; La Forgia, F.; Barbieri, C.

    2014-04-01

    A mineralogical model composed of a mixture of Tagish Lake meteorite (TL) and Pyroxene Glass (PM80) was presented in [1] to explain the surface reflectance of Phobos from 0.25 to 4.0 μm. The positive results we obtained, when comparing the OSIRIS data [2] extended in wavelength to include the [3,4] spectra, forced us to perform a wider comparison between our TL-PM80 model and the CRISM and OMEGA Phobos spectra presented in [5]. Such spectra cover three different regions of interest (ROIs) situated in the Phobos sub-Mars hemisphere: the interior of the Stickney crater, its eastern rim, and its proximity terrain southeast of the Reldresal crater. We decided to vary the percentage mixture of the components of our model (80% TL, 20% PM80), between pure TL and pure PM80, by means of the radiative transfer code based on the [6] formulation of the slab approximation. Once this spectral range was derived, see Fig. 1, we attempted to compare it with the [5] spectra between 0.4 and 2.6 μm, i.e. below the thermal emitted radiation, to see if any spectral match was possible. We observed that CRISM scaled spectra above 1.10 μm fall within pure Tagish Lake composition and the [1] model. The CRISM data below 1.10 μm present more discrepancies with our models, in particular for the Stickney's rim spectrum. Nevertheless the TL and PM80 components seem to be good mineralogical candidates on Phobos. We performed the same analysis with the OMEGA data and, again, we found out that the Stickney's rim spectrum lies out of our model range, while the two remaining spectra still lie between pure TL and 80% TL - 20% PM80, but indicating that a different, more complicated mixture is expected in order to explain properly both the spectral trend and the possible absorption bands located above 2.0 μm. Within this analysis, we point out that a big fraction of TL material (modeled pure or present with a minimum percentage of 80% mixed together with 20% PM80) seems to explain Phobos spectral

  3. Induction of the autophagy-associated gene MAP1S via PU.1 supports APL differentiation.

    PubMed

    Haimovici, Aladin; Brigger, Daniel; Torbett, Bruce E; Fey, Martin F; Tschan, Mario P

    2014-09-01

    The PU.1 transcription factor is essential for myeloid development. We investigated if the microtubule-associated protein 1S (MAP1S) is a novel PU.1 target with a link to autophagy, a cellular recycling pathway. Comparable to PU.1, MAP1S expression was significantly repressed in primary AML blasts as compared to mature neutrophils. Accordingly, MAP1S expression was induced during neutrophil differentiation of CD34(+) progenitor and APL cells. Moreover, PU.1 bound to the MAP1S promoter and induced MAP1S expression during APL differentiation. Inhibiting MAP1S resulted in aberrant neutrophil differentiation and autophagy. Taken together, our findings implicate the PU.1-regulated MAP1S gene in neutrophil differentiation and autophagy control.

  4. Hierarchical analysis of molecular spectra

    SciTech Connect

    Davis, M.J.

    1996-03-01

    A novel representation of molecular spectra in terms of hierarchical trees has proven to be an important aid for the study of many significant problems in gas-phase chemical dynamics. Trees are generated from molecular spectra by monitoring the changes that occur in a spectrum as resolution is changed in a continuous manner. A tree defines a genealogy among all lines of a spectrum. This allows for a detailed understanding of the assignment of features of a spectrum that may be difficult to obtain any other way as well as an understanding of intramolecular energy transfer time scales, mechanisms, and pathways. The methodology has been applied to several problems: transition state spectroscopy, intramolecular energy transfer in highly excited molecules, high-resolution overtone spectroscopy, and the nature of the classical-quantum correspondence when there is classical chaos (``quantum chaos``).

  5. Eigenvectors of optimal color spectra.

    PubMed

    Flinkman, Mika; Laamanen, Hannu; Tuomela, Jukka; Vahimaa, Pasi; Hauta-Kasari, Markku

    2013-09-01

    Principal component analysis (PCA) and weighted PCA were applied to spectra of optimal colors belonging to the outer surface of the object-color solid or to so-called MacAdam limits. The correlation matrix formed from this data is a circulant matrix whose biggest eigenvalue is simple and the corresponding eigenvector is constant. All other eigenvalues are double, and the eigenvectors can be expressed with trigonometric functions. Found trigonometric functions can be used as a general basis to reconstruct all possible smooth reflectance spectra. When the spectral data are weighted with an appropriate weight function, the essential part of the color information is compressed to the first three components and the shapes of the first three eigenvectors correspond to one achromatic response function and to two chromatic response functions, the latter corresponding approximately to Munsell opponent-hue directions 9YR-9B and 2BG-2R.

  6. Accelerated Fitting of Stellar Spectra

    NASA Astrophysics Data System (ADS)

    Ting, Yuan-Sen; Conroy, Charlie; Rix, Hans-Walter

    2016-07-01

    Stellar spectra are often modeled and fitted by interpolating within a rectilinear grid of synthetic spectra to derive the stars’ labels: stellar parameters and elemental abundances. However, the number of synthetic spectra needed for a rectilinear grid grows exponentially with the label space dimensions, precluding the simultaneous and self-consistent fitting of more than a few elemental abundances. Shortcuts such as fitting subsets of labels separately can introduce unknown systematics and do not produce correct error covariances in the derived labels. In this paper we present a new approach—Convex Hull Adaptive Tessellation (chat)—which includes several new ideas for inexpensively generating a sufficient stellar synthetic library, using linear algebra and the concept of an adaptive, data-driven grid. A convex hull approximates the region where the data lie in the label space. A variety of tests with mock data sets demonstrate that chat can reduce the number of required synthetic model calculations by three orders of magnitude in an eight-dimensional label space. The reduction will be even larger for higher dimensional label spaces. In chat the computational effort increases only linearly with the number of labels that are fit simultaneously. Around each of these grid points in the label space an approximate synthetic spectrum can be generated through linear expansion using a set of “gradient spectra” that represent flux derivatives at every wavelength point with respect to all labels. These techniques provide new opportunities to fit the full stellar spectra from large surveys with 15-30 labels simultaneously.

  7. Optical Spectra of Triggered Lightning

    NASA Astrophysics Data System (ADS)

    Walker, T. D.; Biagi, C. J.; Hill, J. D.; Jordan, D. M.; Uman, M. A.; Christian, H. J., Jr.

    2009-12-01

    In August 2009, the first optical spectra of triggered lightning flashes were acquired. Data from two triggered lightning flashes were obtained at the International Center for Lightning Research and Testing in north-central Florida. The spectrometer that was used has an average dispersion of 260 Å/mm resulting in an average resolution of 5 Å when mated to a Photron (SA1.1) high-speed camera. The spectra captured with this system had a free spectral range of 3800-8000 Å. The spectra were captured at 300,000 frames per second. The spectrometer's vertical field of view was 3 m at an altitude 50 m above the launch tower, intended to view the middle of the triggering wire. Preliminary results show that the copper spectrum dominated the earliest part of the flash and copper lines persisted during the total lifetime of the detectable spectrum. Animations over the lifetime of the stroke from the initial wire illumination to multiple return strokes show the evolution of the spectrum. In addition, coordinated high speed channel base current, electric field and imagery measurements of the exploding wire, downward leaders, and return strokes were recorded. Quantitative analysis of the spectral evolution will be discussed in the context of the overall flash development.

  8. Ultraviolet Spectra of Uranian Satellites

    NASA Astrophysics Data System (ADS)

    Roush, Ted

    1996-07-01

    The ultraviolet reflectance spectra of the icy satellites ofUranus are largely unknown. We propose to use the HubbleSpace Telescope Faint Object Spectrograph in order to obtainthe first high S/N UV spectra of Ariel, Titania, and Oberon.Because of our innovative targeting approach, we have alsobeen able to include Umbriel in our observational plans.These satellites sample almost the full range of UV albedosand UV/VIS colors exhibited by the large Uranian satellites.The spectral resolution and range will overlap with earth-based telescopic and spacecraft observations of these objectsallowing for comparisons of the UV data with existing visualand near-infrared spectra of these objects. These comparisonswill ultimately provide greater constraints on the relativelylow albedo spectrally neutral non-ice component on the Uraniansatellites. The existance of UV spectral features due tospecies such as O_3, H_2O_2 or carbon-rich macromolecules(e.g. polycyclic aromatic hydrocarbons) can provide evidencefor modification of the surfaces via plasma or meteoriticbombardment, alteration by high-energy ultraviolet radiation,or accretion of particles from nearby sources such asplanetary rings or dust bands.

  9. Gallium arsenide (GaAs) (001) after sublimation of arsenic (As) thin-film cap, by XPS

    SciTech Connect

    Engelhard, Mark H.; Lyubinetsky, Andre; Baer, Don R.

    2016-12-01

    Survey and high energy resolution spectra are reported for MBE grown GaAs (001) that had been capped with As. The As cap was removed by heating in situ prior to analysis. The current data expands upon the spectral regions previously reported in Surface Science Spectra. High energy resolution spectral features reported include: 2p, 3s, 3p, 3d, and L3M45M45 peaks for As; 2p, 3s, 3p, 3d, and L3M45M45 peaks for Ga; and the valance band region.

  10. Design of an in-house ambient pressure AP-XPS using a bench-top X-ray source and the surface chemistry of ceria under reaction conditions.

    PubMed

    Tao, Franklin Feng

    2012-04-21

    A new in-house ambient pressure XPS (AP-XPS) was designed for the study of surfaces of materials under reaction conditions and during catalysis. Unique features of this in-house AP-XPS are the use of monochromated Al Kα and integration of a minimized reaction cell, and working conditions of up to 500 °C in gases of tens of Torr. Generation of oxygen vacancies on ceria and filling them with oxygen atoms were characterized in operando.

  11. K[beta] spectra of heliumlike iron from TFTR plasmas

    SciTech Connect

    Smith, A.J. ); Bitter, M.; Hsuan, H.; Hill, K.W.; von Goeler, S.; Timberlake, J. . Plasma Physics Lab.); Beiersdorfer, P.; Osterheld, A. )

    1992-12-01

    K[beta] spectra of helium-like iron, Fe XXV, have been observed from TFTR plasmas with a high-resolution crystal spectrometer. The wavelength range of the Fe K[beta] spectrum partially overlaps the spectrum of helium-like nickel (Ni XXVII), which is used on TFTR and JET for ion temperature measurements. The experimental arrangement made it possible to observe the Fe XXV K[beta] lines and their satellite transitions of the type 1s2l[prime]31[double prime] [yields] 1s[sup 2]21[prime], as well as the entire satellite spectrum of the Ni XXVII K [alpha] line simultaneously. In order to identify the features of the K[beta] spectra and to study their possible interference with the Ni XXVII spectrum, the intensity of the K[beta] spectrum was enhanced by injection of iron into the plasma. Accurate wavelengths and intensities have been obtained and compared with different theoretical calculations.

  12. K{beta} spectra of heliumlike iron from TFTR plasmas

    SciTech Connect

    Smith, A.J.; Bitter, M.; Hsuan, H.; Hill, K.W.; von Goeler, S.; Timberlake, J.; Beiersdorfer, P.; Osterheld, A.

    1992-12-01

    K{beta} spectra of helium-like iron, Fe XXV, have been observed from TFTR plasmas with a high-resolution crystal spectrometer. The wavelength range of the Fe K{beta} spectrum partially overlaps the spectrum of helium-like nickel (Ni XXVII), which is used on TFTR and JET for ion temperature measurements. The experimental arrangement made it possible to observe the Fe XXV K{beta} lines and their satellite transitions of the type 1s2l{prime}31{double_prime} {yields} 1s{sup 2}21{prime}, as well as the entire satellite spectrum of the Ni XXVII K {alpha} line simultaneously. In order to identify the features of the K{beta} spectra and to study their possible interference with the Ni XXVII spectrum, the intensity of the K{beta} spectrum was enhanced by injection of iron into the plasma. Accurate wavelengths and intensities have been obtained and compared with different theoretical calculations.

  13. Quantitative analysis of Fe and Co in Co-substituted magnetite using XPS: The application of non-linear least squares fitting (NLLSF)

    NASA Astrophysics Data System (ADS)

    Liu, Hongmei; Wei, Gaoling; Xu, Zhen; Liu, Peng; Li, Ying

    2016-12-01

    Quantitative analysis of Co and Fe using X-ray photoelectron spectroscopy (XPS) is of important for the evaluation of the catalytic ability of Co-substituted magnetite. However, the overlap of XPS peaks and Auger peaks for Co and Fe complicate quantification. In this study, non-linear least squares fitting (NLLSF) was used to calculate the relative Co and Fe contents of a series of synthesized Co-substituted magnetite samples with different Co doping levels. NLLSF separated the XPS peaks of Co 2p and Fe 2p from the Auger peaks of Fe and Co, respectively. Compared with a control group without fitting, the accuracy of quantification of Co and Fe was greatly improved after elimination by NLLSF of the disturbance of Auger peaks. A catalysis study confirmed that the catalytic activity of magnetite was enhanced with the increase of Co substitution. This study confirms the effectiveness and accuracy of the NLLSF method in XPS quantitative calculation of Fe and Co coexisting in a material.

  14. Vacuum annealing phenomena in ultrathin TiDy/Pd bi-layer films evaporated on Si(100) as studied by TEM and XPS.

    PubMed

    Lisowski, W; Keim, E G

    2010-04-01

    Using a combination of TEM and XPS, we made an analysis of the complex high-temperature annealing effect on ultrathin titanium deuteride (TiD(y)) films evaporated on a Si(100) substrate and covered by an ultrathin palladium layer. Both the preparation and annealing of the TiD(y)/Pd bi-layer films were performed in situ under UHV conditions. It was found that the surface and bulk morphology of the bi-layer film as well as that of the Si substrate material undergo a microstructural and chemical conversion after annealing and annealing-induced deuterium evolution from the TiD(y) phase. Energy-filtered TEM (EFTEM) mapping of cross-section images and argon ion sputter depth profiling XPS analysis revealed both a broad intermixing between the Ti and Pd layers and an extensive inter-diffusion of Si from the substrate into the film bulk area. Segregation of Ti at the Pd top layer surface was found to occur by means of angle-resolved XPS (ARXPS) and the EFTEM analyses. Selected area diffraction (SAD) and XPS provided evidence for the formation of a new PdTi(2) bimetallic phase within the top region of the annealed film. Moreover, these techniques allowed to detect the initial stages of TiSi phase formation within the film-substrate interlayer.

  15. Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS.

    PubMed

    Belsey, Natalie A; Cant, David J H; Minelli, Caterina; Araujo, Joyce R; Bock, Bernd; Brüner, Philipp; Castner, David G; Ceccone, Giacomo; Counsell, Jonathan D P; Dietrich, Paul M; Engelhard, Mark H; Fearn, Sarah; Galhardo, Carlos E; Kalbe, Henryk; Won Kim, Jeong; Lartundo-Rojas, Luis; Luftman, Henry S; Nunney, Tim S; Pseiner, Johannes; Smith, Emily F; Spampinato, Valentina; Sturm, Jacobus M; Thomas, Andrew G; Treacy, Jon P W; Veith, Lothar; Wagstaffe, Michael; Wang, Hai; Wang, Meiling; Wang, Yung-Chen; Werner, Wolfgang; Yang, Li; Shard, Alexander G

    2016-10-27

    We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) inter-laboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and; particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage or sample preparation resulted in a variability in thickness of 53 %. The calculation method chosen by XPS participants contributed a variability of 67 %. However, variability of 12 % was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors, since this contributed a variability of 33 %. The results from the LEIS participants were more consistent, with variability of less than 10 % in thickness and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results.

  16. Versailles Project on Advanced Materials and Standards Interlaboratory Study on Measuring the Thickness and Chemistry of Nanoparticle Coatings Using XPS and LEIS

    SciTech Connect

    Belsey, Natalie A.; Cant, David J. H.; Minelli, Caterina; Araujo, Joyce R.; Bock, Bernd; Brüner, Philipp; Castner, David G.; Ceccone, Giacomo; Counsell, Jonathan D. P.; Dietrich, Paul M.; Engelhard, Mark H.; Fearn, Sarah; Galhardo, Carlos E.; Kalbe, Henryk; Kim, Jeong Won; Lartundo-Rojas, Luis; Luftman, Henry S.; Nunney, Tim S.; Pseiner, Johannes; Smith, Emily F.; Spampinato, Valentina; Sturm, Jacobus M.; Thomas, Andrew G.; Treacy, Jon P. W.; Veith, Lothar; Wagstaffe, Michael; Wang, Hai; Wang, Meiling; Wang, Yung-Chen; Werner, Wolfgang; Yang, Li; Shard, Alexander G.

    2016-10-27

    We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) inter-laboratory study on the measurement of the shell thickness and chemistry of nanoparticle coatings. Peptide-coated gold particles were supplied to laboratories in two forms: a colloidal suspension in pure water and; particles dried onto a silicon wafer. Participants prepared and analyzed these samples using either X-ray photoelectron spectroscopy (XPS) or low energy ion scattering (LEIS). Careful data analysis revealed some significant sources of discrepancy, particularly for XPS. Degradation during transportation, storage or sample preparation resulted in a variability in thickness of 53 %. The calculation method chosen by XPS participants contributed a variability of 67 %. However, variability of 12 % was achieved for the samples deposited using a single method and by choosing photoelectron peaks that were not adversely affected by instrumental transmission effects. The study identified a need for more consistency in instrumental transmission functions and relative sensitivity factors, since this contributed a variability of 33 %. The results from the LEIS participants were more consistent, with variability of less than 10 % in thickness and this is mostly due to a common method of data analysis. The calculation was performed using a model developed for uniform, flat films and some participants employed a correction factor to account for the sample geometry, which appears warranted based upon a simulation of LEIS data from one of the participants and comparison to the XPS results.

  17. Optical and XPS studies of BCN thin films by co-sputtering of B4C and BN targets

    NASA Astrophysics Data System (ADS)

    Prakash, Adithya; Sundaram, Kalpathy B.

    2017-02-01

    Boron carbon nitride (BCN) thin films are investigated for their optical properties. BCN, is the unanimous choice for inter-dielectric layer (IDL) in very large scale integration (VLSI) because of its low-k dielectric constant. Optical properties can be tailored as a function of elemental composition, which makes BCN a prospective material in UV-filters and mirrors. Films are deposited by reactive co-sputtering of boroncarbide (B4C) and boronnitride (BN) with varying N2/Ar gas flow ratio by DC and RF sputtering respectively. XPS studies are performed to deduce the bonding and chemical properties of the BCN thinfilms. Optical band gap (Eg) studies are performed as a result of varying target powers, gas ratios and deposition temperatures. Eg is found to increase with N2/Ar flow ratios and deposition temperatures. BCN deposited at 20 W DC exhibited higher band gap range and the highest achieved is 3.7 eV at N2/Ar = 0.75. Lowest value achieved is 1.9 eV at N2/Ar = 0.25 for as-deposited films.

  18. Mutation in the xpsD gene of Xanthomonas axonopodis pv. citri affects cellulose degradation and virulence.

    PubMed

    Baptista, Juliana Cristina; Machado, Marcos Antonio; Homem, Rafael Augusto; Torres, Pablo Sebastián; Vojnov, Adrian Alberto; do Amaral, Alexandre Morais

    2010-01-01

    The Gram-negative bacterium Xanthomonas axonopodis pv. citri, the causal agent of citrus canker, is a major threat to the citrus industry worldwide. Although this is a leaf spot pathogen, it bears genes highly related to degradation of plant cell walls, which are typically found in plant pathogens that cause symptoms of tissue maceration. Little is known on Xac capacity to cause disease and hydrolyze cellulose. We investigated the contribution of various open reading frames on degradation of a cellulose compound by means of a global mutational assay to selectively screen for a defect in carboxymethyl cellulase (CMCase) secretion in X. axonopodis pv. citri. Screening on CMC agar revealed one mutant clone defective in extracellular glycanase activity, out of nearly 3,000 clones. The insertion was located in the xpsD gene, a component of the type II secretion system (T2SS) showing an influence in the ability of Xac to colonize tissues and hydrolyze cellulose. In summary, these data show for the first time, that X. axonopodis pv. citri is capable of hydrolyzing cellulose in a T2SS-dependent process. Furthermore, it was demonstrated that the ability to degrade cellulose contributes to the infection process as a whole.

  19. Single-layer ZnS supported on Au(111): A combined XPS, LEED, STM and DFT study

    NASA Astrophysics Data System (ADS)

    Deng, Xingyi; Sorescu, Dan C.; Lee, Junseok

    2017-04-01

    Single-layer of ZnS, consisting of one atomic layer of ZnS(111) plane, has been grown on Au(111) and characterized using X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). While the LEED measurement indicates a coincidence structure of ZnS-(3×3)/Au(111)-(4×4), high resolution STM images reveal hexagonal unit cells of 6.7×6.7 Å2 and 11.6×11.6 Å2, corresponding to √3 and 3 times the unit cell of the ideal zincblende ZnS-(1×1), respectively, depending on the tunneling conditions. Calculations based on density functional theory (DFT) indicate a significantly reconstructed non-planar structure of ZnS single-layer on Au(111) with 2/3 of the S anions being located nearly in the plane of the Zn cations and the rest 1/3 of the S anions protruding above the Zn plane. The calculated STM image shows similar characteristics to those of the experimental STM image. Additionally, the DFT calculations reveal the different bonding nature of the S anions in ZnS single-layer supported on Au(111).

  20. Eu(III) sorption to TiO2 (anatase and rutile): batch, XPS, and EXAFS studies.

    PubMed

    Tan, Xiaoli; Fan, Qiaohui; Wang, Xiangke; Grambow, Bernd

    2009-05-01

    The sorption of Eu(III) on anatase and rutile was studied as a function of ionic strength, humic acid (HA, 7.5 mg/L), and electrolyte anions over a large range of pH (2-12). The presence of HA significantly affected Eu(III) sorption to anatase and rutile. The sorption of Eu(III) on anatase and rutile was independent of ionic strength. Results of an X-ray photoelectron spectroscopy (XPS) analysis showed that Eu(III) was chemically present within the near-surface of TiO2 due to the formation of triple bond SOEu and triple bond SOHAEu complexes. An extended X-ray absorption fine structure (EXAFS) technique was applied to characterize the local structural environment of the adsorbed Eu(III), and the results indicated that Eu(III) was bound to about seven or eight O atoms at a distance of about 2.40 A. The functional groups of surface-bound HA were expected to be involved in the sorption process. The measured Eu-Ti distance confirmed the formation of inner-sphere sorption complexes on a TiO2 surface.

  1. A study of the initial film growth of PEG-like plasma polymer films via XPS and NEXAFS

    NASA Astrophysics Data System (ADS)

    Li, Yali; Muir, Benjamin W.; Easton, Christopher D.; Thomsen, Lars; Nisbet, David R.; Forsythe, John S.

    2014-01-01

    The chemistry of substrate-film interface (underside) of di(ethylene glycol) dimethyl ether plasma polymer (DGpp) films has been studied directly and compared to the top layer of the film (topside). By depositing the plasma polymer films onto indium tin oxide (ITO) glass, the films were easily delaminated from the substrate. The top- and underside of the films were examined by X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. It was found that a rapid increase in pressure during plasma polymerization results in steep chemical gradients in the films, while small pressure changes do not lead to chemical gradient formation. These observations validate the findings of previous neutron reflectometry modeling studies of this class of plasma polymer thin film. In addition, subtle variations in plasma polymer film chemistry were observed between different substrates they were deposited onto. This approach will allow additional studies on the mechanisms of early plasma polymer thin film formation with various monomers.

  2. An XPS study of the stability of Fomblin Z25 on the native oxide of aluminum. [x ray photoelectron spectroscopy

    NASA Technical Reports Server (NTRS)

    Herrera-Fierro, Pilar; Pepper, Stephen V.; Jones, William R.

    1991-01-01

    Thin films of Fomblin Z25, a perfluoropolyalkylether lubricant, were vapor deposited onto clean, oxidized aluminum and sapphire surfaces, and their behavior at different temperatures was studied using x ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). It was found that the interfacial fluid molecules decompose on the native oxide at room temperature, and continue to decompose at elevated temperatures, as previous studies had shown to occur on clean metal. TDS indicated that different degradation mechanisms were operative for clean and oxidized aluminum. On sapphire substrates, no reaction was observed at room temperature. Our conclusion is that the native oxide of aluminum is neither passive nor protective towards Fomblin Z25. At high temperatures (150 C) degradation of the polymer on sapphire produced a debris layer at the interface with a chemical composition similar to the one formed on aluminum oxide. Rubbing a Fomblin film on a single crystal sapphire also induced the decomposition of the lubricant in contact with the interface and the formulation of a debris layer.

  3. The in situ characterization and structuring of electrografted polyphenylene films on silicon surfaces. An AFM and XPS study.

    PubMed

    Ghorbal, Achraf; Grisotto, Federico; Laudé, Marion; Charlier, Julienne; Palacin, Serge

    2008-12-15

    An atomic force microscope was used so as to structure by nanofriction films of polynitrophenylene electrografted on substrates of n-type silicon (100) with the native oxide on the top of the surface. AFM measurements of thin films thickness have been carried out in the electrolytic solution for different applied potentials during the electrografting. This investigation allows (i) to determine the relationship between the applied potential and the final thickness of electrografted polyphenylene films and (ii) to specify how the thin layers grow. XPS analysis confirmed the AFM observations on (i) the effective shaving of the grafted polymer chains under mechanical stress and (ii) the existence of a potential threshold for electrografting a polyphenylene film on silicon oxide surfaces. The presence of a residual film in the rubbed zone was attributed to stronger interactions between the first electrografted layer and the native oxide of silicon (through Si-C or/and Si-O-C bonds) than those insuring the cohesion of the multilayer (C-C and C-N bonds).

  4. A SIMS (secondary ion mass spectrometry) and XPS (X-ray photoelectron spectroscopy) study of dissolving plagioclase

    SciTech Connect

    Muir, I.J. ); Bancroft, G.M.; Nesbitt, H.W. ); Shotyk, W. )

    1990-08-01

    In an earlier report, the authors showed that altered layers formed on the surface of dissolving labradorite feldspar grains, and that the thickness of these layers (up to hundreds of angstroms) is strongly dependent on the pH of the reactant solution. In this paper, they show that the thickness of these altered layers also depends strongly on the composition of the plagioclase feldspar. Secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS) have been used to characterize these altered layers. During dissolution, Ca and Al are removed from the solid material to form an altered layer residually enriched in Si with very similar profiles for Ca and Al. In acidic solutions (pH 3.5) for 90 days, the altered layers increase in thickness from a few hundred angstroms to many hundred angstroms in the order: albite < oligoclase < labradorite < bytownite. These results emphasize the central role of hydrolysis of the bridging Si-O-Al bonds in the initial weathering process. Analysis by scanning electron microscopy (SEM) does not provide any evidence for the growth of secondary phases. Extensive dissolution features (etch pits) were observed on many of the reacted surfaces.

  5. Conservation of artists' acrylic emulsion paints: XPS, NEXAFS and ATR-FTIR studies of wet cleaning methods

    DOE PAGES

    Willneff, E. A.; Ormsby, B. A.; Stevens, J. S.; ...

    2014-02-17

    Works of art prepared with acrylic emulsion paints became commercially available in the 1960s. It is increasingly necessary to undertake and optimise cleaning and preventative conservation treatments to ensure their longevity. Model artists' acrylic paint films covered with artificial soiling were thus prepared on a canvas support and exposed to a variety of wet cleaning treatments based on aqueous or hydrocarbon solvent systems. This included some with additives such as chelating agents and/or surfactants, and microemulsion systems made specifically for conservation practice. The impact of cleaning (soiling removal) on the paint film surface was examined visually and correlated with resultsmore » of attenuated total reflection Fourier transform infrared, XPS and near-edge X-ray absorption fine structure analyses – three spectroscopic techniques with increasing surface sensitivity ranging from approximately $-$ 1000, 10 and 5 nm, respectively. Visual analysis established the relative cleaning efficacy of the wet cleaning treatments in line with previous results. X-ray spectroscopy analysis provided significant additional findings, including evidence for (i) surfactant extraction following aqueous swabbing, (ii) modifications to pigment following cleaning and (iii) cleaning system residues.« less

  6. Conservation of artists' acrylic emulsion paints: XPS, NEXAFS and ATR-FTIR studies of wet cleaning methods

    SciTech Connect

    Willneff, E. A.; Ormsby, B. A.; Stevens, J. S.; Jaye, C.; Fischer, D. A.; Schroeder, S. L. M.

    2014-02-17

    Works of art prepared with acrylic emulsion paints became commercially available in the 1960s. It is increasingly necessary to undertake and optimise cleaning and preventative conservation treatments to ensure their longevity. Model artists' acrylic paint films covered with artificial soiling were thus prepared on a canvas support and exposed to a variety of wet cleaning treatments based on aqueous or hydrocarbon solvent systems. This included some with additives such as chelating agents and/or surfactants, and microemulsion systems made specifically for conservation practice. The impact of cleaning (soiling removal) on the paint film surface was examined visually and correlated with results of attenuated total reflection Fourier transform infrared, XPS and near-edge X-ray absorption fine structure analyses – three spectroscopic techniques with increasing surface sensitivity ranging from approximately $-$ 1000, 10 and 5 nm, respectively. Visual analysis established the relative cleaning efficacy of the wet cleaning treatments in line with previous results. X-ray spectroscopy analysis provided significant additional findings, including evidence for (i) surfactant extraction following aqueous swabbing, (ii) modifications to pigment following cleaning and (iii) cleaning system residues.

  7. Advancements in the characterization of 'hyper-thin' oxynitride gate dielectrics through exit wave reconstruction HRTEM and XPS

    SciTech Connect

    Principe, E.L.; Watson, D.G.; Kisielowski, C.

    2002-09-01

    The physical thickness of silicon oxynitride gate dielectric materials currently in development have dimensions in the range of 15-20 Angstrom ({approx}6-8 oxygen atoms), while approaching the dielectric constant equivalent oxide thickness (EOT) of 12 Angstrom silicon dioxide. These structures present serious challenges in meeting stringent requirements within the semiconductor industry for precise determination of thickness, interfacial roughness and chemical distribution. Limitations in conventional HRTEM must be removed that would minimize errors in such measurements. Our approach was to use the National Center for Electron Microscopy (NCEM) One Angstrom Microscope (O Angstrom M), together with focal series acquisition (FSA) and exit wave reconstruction (EWR) techniques to obtain <0.8A interpretable resolution. HRTEM data on the same oxynitride materials from an aberration corrected (Cs=0) microscope were also collected as part of this work, as were scanning TEM (STEM) measurements. The H RTEM characterization provides an absolute calibration and validation for a precise ''near-line'' metrology to determine gate oxide thickness and nitrogen dose using x-ray photoelectron spectroscopy (XPS).

  8. Mutation in the xpsD gene of Xanthomonas axonopodis pv. citri affects cellulose degradation and virulence

    PubMed Central

    2010-01-01

    The Gram-negative bacterium Xanthomonas axonopodis pv. citri, the causal agent of citrus canker, is a major threat to the citrus industry worldwide. Although this is a leaf spot pathogen, it bears genes highly related to degradation of plant cell walls, which are typically found in plant pathogens that cause symptoms of tissue maceration. Little is known on Xac capacity to cause disease and hydrolyze cellulose. We investigated the contribution of various open reading frames on degradation of a cellulose compound by means of a global mutational assay to selectively screen for a defect in carboxymethyl cellulase (CMCase) secretion in X. axonopodis pv. citri. Screening on CMC agar revealed one mutant clone defective in extracellular glycanase activity, out of nearly 3,000 clones. The insertion was located in the xpsD gene, a component of the type II secretion system (T2SS) showing an influence in the ability of Xac to colonize tissues and hydrolyze cellulose. In summary, these data show for the first time, that X. axonopodis pv. citri is capable of hydrolyzing cellulose in a T2SS-dependent process. Furthermore, it was demonstrated that the ability to degrade cellulose contributes to the infection process as a whole. PMID:21637619

  9. Action spectra for photosynthetic inhibition

    NASA Technical Reports Server (NTRS)

    Caldwell, M. M.; Flint, S.; Camp, L. B.

    1981-01-01

    The ultraviolet action spectrum for photosynthesis inhibition was determined to fall between that of the general DNA action spectrum and the generalized plant action spectrum. The characteristics of this action spectrum suggest that a combination of pronounced increase in effectiveness with decreasing wavelength, substantial specificity for the UV-B waveband, and very diminished response in the UV-A waveband result in large radiation amplification factors when the action spectra are used as weighting functions. Attempted determination of dose/response relationships for leaf disc inhibition provided inconclusive data from which to deconvolute an action spectrum.

  10. Two slow meteors with spectra

    NASA Astrophysics Data System (ADS)

    Dubs, Martin; Sposetti, Stefano; Spinner, Roger; Booz, Beat

    2017-01-01

    On January 2, 2017 two peculiar meteors (M20170102_001216 and M20170102_015202) were observed by several stations in Switzerland. Both had a long duration, slow velocity, similar brightness and a very similar radiant. As they appeared in a time interval of 100 minutes, a satellite was suspected as a possible origin of these two observations. A closer inspection however showed that this interpretation was incorrect. The two objects were slow meteors. Spectra were taken from both objects, which were nearly identical. Together this points to a common origin of the two meteors.

  11. The Optical Spectra of Aerosols.

    DTIC Science & Technology

    1983-10-01

    espressione dell’ampiezza di diffusione in * avanti vengono fattorizzati. In questo modo la somma delle am- piezze di diftusione di "cluster" con...F1D-Ali35 687 THE OPTICAL SPECTRA OF REROSOLSOU) MESSINA UNIV (ITALY) i/i 1ST DI STRIJTTURA DELLA IIATERIA F BORIIHESE OCT 83 UNCLASSIFIED DRR78--85F...ELEMENT PROJECT, TASK AREA & WORK UNIT NUMBERS * Istituto di Struttura della Materia 61102A-1T161102-BH57-01 Un iversita di Messina V~nina. Ttalv St

  12. Oscillator strengths for 1s2 1S0-1s2p 3P1,2 transitions in helium-like carbon, nitrogen and oxygen including the effects of a finite nuclear mass

    NASA Astrophysics Data System (ADS)

    Morton, Donald C.; Drake, G. W. F.

    2016-12-01

    We have calculated the electric dipole (E1) and magnetic quadrupole (M2) oscillator strengths and spontaneous decay rates for the 1{{{s}}}2{}1{{{S}}}0{--}1{{s}}2{{p}}{}3{{{P}}}{1,2} spin-changing transitions of helium-like C v, N vi and O vii. We added the effects of the finite nuclear mass and the anomalous magnetic moment of the electron including an extra term derived by Pachucki. For the E1 calculations we used the Breit approximation and pseudostate expansions to perform the perturbation sums over intermediate states in both the length and velocity gauge as a check on numerical accuracy and the validity of the transition operators. There is some cancellation in the corrections for the nuclear mass and the electron anomaly so that if one is included the other should not be ignored

  13. Method of processing positron lifetime spectra

    SciTech Connect

    Valuev, N.P.; Klimov, A.B.; Zhikharev, A.N.

    1985-05-01

    This paper describes a method for the processing of spectra of positron annihilation which permits a much more relaible determination of the lifetime during numerical processing of spectra by computer.

  14. Infrared Spectra of Polycyclic Aromatic Hydrocarbons (PAHs)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Bakes, E. L. O.

    2000-01-01

    We have computed the synthetic infrared spectra of some polycyclic aromatic hydrocarbons containing up to 54 carbon atoms. The species studied include ovalene, circumcoronene, dicoronylene, and hexabenzocoronene. We report spectra for anions, neutrals, cations, and multiply charged cations.

  15. Visible Spectra of Titanium Dioxide

    NASA Astrophysics Data System (ADS)

    Gupta, V.; Nagarajan, R.; Maier, J. P.; Zhuang, X.; Le, A.; Steimle, T. C.

    2011-05-01

    Titanium oxide (TiO) has been extensively studied spectroscopically due to its astrophysical relevance. TiO is the main opacity source in the atmospheres of cool M-type stars in the visible and near infrared. In view of the high cosmic abundance of Ti and O, titanium dioxide (TiO2) is believed to play an important role in dust formation processes from the gas-phase in circumstellar shells of oxygen-rich stars. The electronic spectra of a cold molecular beam of TiO2 have been investigated using mass-resolved resonance enhanced multi-photon ionization and laser induced fluorescence spectroscopy. TiO2 was produced by laser ablation of a pure titanium rod in the presence of a supersonic expanding mixture of approximately 5% O2 in either helium or argon. The spectra were recorded in the region 17500 cm-1 to 22500 cm-1 and the bands assigned to the A1B2 ← X1A1 transition. The origin and harmonic vibrational constants for the A1B2 state were determined to be: T000 = 17593(5) cm-1, ω1 = 876(3) cm-1, ω2 = 184(1) cm-1, and ω3 = 316(2) cm-1. Further, the dispersed fluorescence of a few bands were recorded to obtain vibrational parameters for the X1A1 state.

  16. Observation of the Inclusive D^{* -} Production in the Decay of Y(1S)

    SciTech Connect

    Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Tico, J.Garra; Grauges, E.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D.N.; Hooberman, B.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G. /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, San Diego /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /Harvard U. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /Mt. Holyoke Coll. /INFN, Naples /Naples U. /INFN, Naples /INFN, Naples /Naples U. /NIKHEF, Amsterdam /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /Pennsylvania U. /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /Rome U. /INFN, Rome /Rome U. /Rome U. /INFN, Rome /Rome U. /INFN, Rome /Rome U. /Rome U. /INFN, Rome /Rome U. /INFN, Rome /Rome U. /Rome U. /INFN, Rome /Rome U. /INFN, Rome /Rome U. /Rome U. /INFN, Rome /Rome U. /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas Nuclear Corp., Austin /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U. /Victoria U. /Warwick U. /Wisconsin U., Madison

    2009-12-17

    The authors present a study of the inclusive D*{sup {+-}} production in the decay of {Upsilon}(1S) using (98.6 {+-} 0.9) x 10{sup 6} {Upsilon}(2S) mesons collected with the BABAR detector at the {Upsilon}(2S) resonance. Using the decay chain {Upsilon}(2S) {yields} {pi}{sup +}{pi}{sup -}{Upsilon}(1S), {Upsilon}(1S) {yields} D*{sup {+-}}X, where X is unobserved, they measure the branching fraction {Beta}[{Upsilon}(1S) {yields} D*{sup {+-}}X] = (2.52 {+-} 0.13(stat) {+-} 0.15(syst))% and the D*{sup {+-}} momentum distribution in the rest frame of the {Upsilon}(1S). They find evidence for an excess of D*{sup {+-}} production over the expected rate from the virtual photon annihilation process {Upsilon}(1S) {yields} {gamma}* {yields} c{bar c} {yields} D*{sup {+-}} X.

  17. The Attachment of Amino Fragment to Purine: Inner-Shell Structures And Spectra

    SciTech Connect

    Saha, Saumitra; Wang, Feng; MacNaughton, Janay B.; Moewes, Alex; Chong, Denalo P.; /British Columbia U.

    2009-05-11

    The impact of the amino fragment (-NH{sub 2}) attachment on the inner-shell structures and spectra of unsubstituted purine and the purine ring of adenine are studied. Density functional theory calculations, using the LB94/TZ2P//B3LYP/TZVP model, reveal significant site-dependent electronic structural changes in the inner shell of the species. A condensed Fukui function indicates that all of the N and C sites, except for N{sub (1)} and C{sub (5)}, demonstrate significant electrophilic reactivity (f > 0.5 in |e|) in the unsubstituted purine. Once the amino fragment binds to the C{sub (6)} position of purine to form adenine, the electrophilic reactivity of these N and C sites is greatly reduced. As expected, the C{sub (6)} position experiences substantial changes in energy and charge transfer, owing to the formation of the C-NH{sub 2} bond in adenine. The present study reveals that the N1s spectra of adenine inherit the N1s spectra of the unsubstituted purine, whereas the C1s spectra experience significant changes although purine and adenine have geometrically similar carbon frames. The findings also indicate that the attachment of the NH{sub 2} fragment to purine exhibits deeply rooted influences to the inner-shell structures of DNA/RNA bases. The present study suggests that some fragment-based methods may not be applicable to spectral analyses in the inner shell.

  18. The ϒ(1S)→Bcρ decay with perturbative QCD approach

    NASA Astrophysics Data System (ADS)

    Sun, Junfeng; Yang, Yueling; Li, Qingxia; Lu, Gongru; Huang, Jinshu; Chang, Qin

    2016-08-01

    With the potential prospects of the ϒ (1 S) data samples at the running LHC and upcoming SuperKEKB, the ϒ (1 S) →Bc ρ weak decay is studied with the pQCD approach. It is found that (1) the lion's share of branching ratio comes from the longitudinal polarization helicity amplitudes; (2) branching ratio for the ϒ (1 S) →Bc ρ decay can reach up to O (10-9), which might be hopefully measurable.

  19. Jade-1S phosphorylation induced by CK1α contributes to cell cycle progression.

    PubMed

    Borgal, Lori; Rinschen, Markus M; Dafinger, Claudia; Liebrecht, Valérie I; Abken, Hinrich; Benzing, Thomas; Schermer, Bernhard

    2016-01-01

    The PHD zinc finger protein Jade-1S is a component of the HBO1 histone acetyltransferase complex and binds chromatin in a cell cycle-dependent manner. Jade-1S also acts as an E3 ubiquitin ligase for the canonical Wnt effector protein β-catenin and is influenced by CK1α-mediated phosphorylation. To further elucidate the functional impact of this phosphorylation, we used a stable, low-level expression system to express either wild-type or mutant Jade-1S lacking the N-terminal CK1α phosphorylation motif. Interactome analyses revealed that the Jade-1S mutant unable to be phosphorylated by CK1α has an increased binding affinity to proteins involved in chromatin remodelling, histone deacetylation, transcriptional repression, and ribosome biogenesis. Interestingly, cells expressing the mutant displayed an elongated cell shape and a delay in cell cycle progression. Finally, phosphoproteomic analyses allowed identification of a Jade-1S site phosphorylated in the presence of CK1α but closely resembling a PLK1 phosphorylation motif. Our data suggest that Jade-1S phosphorylation at an N-terminal CK1α motif creates a PLK1 phospho-binding domain. We propose CK1α phosphorylation of Jade 1S to serve as a molecular switch, turning off chromatin remodelling functions of Jade-1S and allowing timely cell cycle progression. As Jade-1S protein expression in the kidney is altered upon renal injury, this could contribute to understanding mechanisms underlying epithelial injury repair.

  20. XPS, SIMS and FTIR-ATR characterization of boronized graphite from the thermonuclear plasma device RFX-mod

    NASA Astrophysics Data System (ADS)

    Ghezzi, F.; Laguardia, L.; Caniello, R.; Canton, A.; Dal Bello, S.; Rais, B.; Anderle, M.

    2015-11-01

    In this paper the characterization of a thin (tens of nanometers) boron layer on fine grain polycrystalline graphite substrate is presented. The boron film is used as conditioning technique for the full graphite wall of the Reversed Field eXperiment-modified (RFX-mod) experiment, a device for the magnetic confinement of plasmas of thermonuclear interest. Aim of the present analysis is to enlighten the chemical structure of the film, the trapping mechanism that makes it a getter for oxygen and hydrogen and the reason of its loss of effectiveness after exposure to about 100 s of hydrogen plasma. X-ray Photoelectron Spectroscopy (XPS), Secondary Ions Mass Spectrometry (SIMS) and Fourier Transform Infra Red spectroscopy in combination with the Attenuated Total Reflectance (FTIR-ATR) were used to obtain the structure and the chemical composition of graphitic samples as coated or coated and subsequently exposed to hydrogen plasma after boron deposition. The boron layers on the only coated samples were found to be amorphous hydrogenated boron carbide plus a variety of bonds like B-B, B-H, B-O, B-OH, C-C, C-H, C-O, C-OH. Both the thickness and the homogeneity of the layers were found to depend on the distance of the sample from the anode during the deposition. The samples contained oxygen along the layer thickness, at level of 5%, bound to boron. The gettering action of the boron is therefore already active during the deposition itself. The exposure to plasma caused erosion of the boron film and higher content of H and O bound to boron throughout the whole thickness. The interaction of the B layer with plasma is therefore a bulk phenomenon.

  1. Effect of sulfate on Cu(II) sorption to polymer-supported nano-iron oxides: behavior and XPS study.

    PubMed

    Qiu, Hui; Zhang, Shujuan; Pan, Bingcai; Zhang, Weiming; Lv, Lu

    2012-01-15

    Iron oxides tend to be immobilized within nanoporous supports to improve their feasibility for practical environmental remediation including arsenic and heavy metal removal. Contrary to the co-ions, little is known concerning the effect of counter ions on the performance of the resultant composites. In this study, two hybrid sorbents (denoted as HFO-PS(-) and HFO-PS(0), respectively) were prepared by loading hydrous ferric oxide (HFO) nanoparticles onto two polystyrene beads: PS(-), negatively charged with sulfonic acid groups, and PS(0), covalently bonded with neutral chloromethyl groups. Effects of sulfate on their sorption toward Cu ions were investigated. Consistent with the case in bulky HFO particles, the amount of Cu adsorbed on HFO-PS(0) was markedly promoted by introducing sulfate. As for HFO-PS(-), with monovalent cation as background (Na(+)), it exhibited an apparent decrease in Cu sorption as a result of the competing effect of Na ions and the Cu-SO(4) complexation in solution. Contrarily, the adsorbed Cu was increased by introducing sulfate in the divalent cation background (Ca), because sulfate ions were allowed to access to the loaded HFO nanoparticles due to the screening of the sulfonic acid groups caused by Ca ions. XPS spectroscopy further demonstrated that besides the electrostatic effects, the formation of Cu-SO(4) ternary complexes also accounted for the enhanced Cu sorption on both bulky HFO and hybrid HFO sorbents in the presence of sulfate. These results indicated that the effect of counter-ion ligands on metal adsorption to hybrid iron oxides was largely dependent on the surface properties of the host materials.

  2. Neutron and photon spectra in LINACs.

    PubMed

    Vega-Carrillo, H R; Martínez-Ovalle, S A; Lallena, A M; Mercado, G A; Benites-Rengifo, J L

    2012-12-01

    A Monte Carlo calculation, using the MCNPX code, was carried out in order to estimate the photon and neutron spectra in two locations of two linacs operating at 15 and 18 MV. Detailed models of both linac heads were used in the calculations. Spectra were estimated below the flattening filter and at the isocenter. Neutron spectra show two components due to evaporation and knock-on neutrons. Lethargy spectra under the filter were compared to the spectra calculated from the function quoted by Tosi et al. that describes reasonably well neutron spectra beyond 1 MeV, though tends to underestimate the energy region between 10(-6) and 1 MeV. Neutron and the Bremsstrahlung spectra show the same features regardless of the linac voltage.

  3. Spectra from pair-equilibrium plasmas

    NASA Technical Reports Server (NTRS)

    Zdziarski, A. A.

    1984-01-01

    A numerical model of relativistic nonmagnetized plasma with uniform temperature and electron density distributions is considered, and spectra from plasma in pair equilibrium are studied. A range of dimensionless temperature (T) greater than about 0.2 is considered. The spectra from low pair density plasmas in pair equilibrium vary from un-Comptonized bremsstrahlung spectra at Thomson cross section tau(N) much less than one to Comptonized bremsstrahlung spectra with tau(N) over one. For high pair density plasmas the spectra are flat for T greater than about one, and have broad intensity peaks at energy roughly equal to 3T for T less than one. In the latter region the total luminosity is approximately twice the annihilation luminosity. All spectra are flat in the X-ray region, in contradiction to observed AGN spectra. For dimensionless luminosity greater than about 100, the cooling time becomes shorter than the Thomson time.

  4. [Vibrational spectra of Corallium elatius].

    PubMed

    Fan, Lu-wei; Zhang, Yan; Hu, Yang

    2013-09-01

    Corallium elatius, which has unique color distribution characteristic, is the most important species of Taiwan precious corals. EPMA, XRD, FTIR and Laser Raman detective methods were used to study the chemical, mineral composition and spectra characteristics of Corallium elatius. The result of EPMA, XRD and FTIR shows the high-Mg calcite mineral componentand the stable minor chemical constituents of the samples. Meanwhile, the cell parameter indicates the lattice distortion and the preferred orientation of calcite grain caused by organic matter. The red part of the samples shows a different Raman spectrum from that of the white part, located at 1517/1128 cm(-1) and 1296/1016 cm(-1). Raman scattering measurement reveals the relationship between the organic matter and color.

  5. Power spectra of solar convection

    NASA Technical Reports Server (NTRS)

    Chou, D.-Y.; Labonte, B. J.; Braun, D. C.; Duvall, T. L., Jr.

    1991-01-01

    The properties of convective motions on the sun are studied using Kitt Peak Doppler images and power spectra of convection. The power peaks at a scale of about 29,000 km and drops off smoothly with wavenumber. There is no evidence of apparent energy excess at the scale of the mesogranulation proposed by other authors. The vertical and horizontal power for each wavenumber are obtained and used to calculate the vertical and horizontal velocities of the supergranulation. The amplitude of vertical and horizontal velocities of the supergranulation are 0.034 (+ or - 0.002) km/s and 0.38 (+ or - 0.01) km/s, respectively. The corresponding rms values are 0.024 (+ or - 0.002) km/s and 0.27 (+ or - 0.01) km/s.

  6. Reflectance spectra of primitive chondrites

    NASA Astrophysics Data System (ADS)

    Trigo-Rodríguez, J. M.; Moyano-Cambero, C. E.; Llorca, J.

    2013-05-01

    We are studying a wide sample of pristine carbonaceous chondrites from the NASA Antarctic collection in order to get clues on the physico-chemical processes occurred in the parent bodies of these meteorites. We are obtaining laboratory reflectance spectra of different groups of carbonaceous chondrites, but here we focus in CM and CI chondrites. We discuss the main spectral features that can be used to identify primitive carbonaceous asteroids by remote sensing techniques. Two different spectrometers were used covering the entire 0.3 to 30 μm electromagnetic window. Only a handful of Near Earth Objects (NEOs) exhibit bands or features clearly associated with aqueous alteration. Among them are the target asteroids of Osiris Rex and Marco Polo-R missions.

  7. Pressure spectra and cross spectra at an area contraction in a ducted combustion system

    NASA Technical Reports Server (NTRS)

    Miles, J. H.; Raftopoulos, D. D.

    1980-01-01

    Pressure spectra and cross-spectra at an area contraction in a liquid fuel, ducted, combustion noise test facility are analyzed. Measurements made over a range of air and fuel flows are discussed. Measured spectra are compared with spectra calculated using a simple analytical model.

  8. Line Coupling in Atmospheric Spectra

    NASA Technical Reports Server (NTRS)

    Tipping, R. H.

    1996-01-01

    The theoretical modeling of atmospheric spectra is important for a number of different applications: for instance, in the determination of minor atmospheric constituents such as ozone, carbon dioxide, CFC's etc.; in monitoring the temperature profile for climate studies; and in measuring the incoming and outgoing radiation to input into global climate models. In order to accomplish the above mentioned goal, one needs to know the spectral parameters characterizing the individual spectral lines (frequency, width, strength, and shape) as well as the physical parameters of the atmosphere (temperature, abundances, and pressure). When all these parameters are known, it is usually assumed that the resultant spectra and concomitant absorption coefficient can then be calculated by a superposition of individual profiles of appropriate frequency, strength and shape. However, this is not true if the lines are 'coupled'. Line coupling is a subtle effect that takes place when lines of a particular molecule overlap in frequency. In this case when the initial states and the final states of two transitions are connected by collisions, there is a quantum interference resulting in perturbed shapes. In general, this results in the narrowing of Q-branches (those in which the rotational quantum number does not change), and vibration-rotational R- and P branches (those in which the rotational quantum number changes by +/- 1), and in the spectral region beyond band heads (regions where the spectral lines pile up due to centrifugal distortion). Because these features and spectral regions are often those of interest in the determination of the abundances and pressure-temperature profiles, one must take this effect into account in atmospheric models.

  9. Occupied and unoccupied orbitals of C{sub 60} and C{sub 70} probed with C 1s emission and absorption

    SciTech Connect

    Carlisle, J.A.; Terminello, L.J.; Hudson, E.A.

    1997-04-01

    The aim of this work is to characterize the orbital structure of the fullerenes, and to pursue its evolution from a cluster to the infinite solid. For obtaining a complete picture of the electronic structure the authors compare a variety of experimental techniques, i.e. photoemission and core level emission for occupied orbitals and inverse photoemission and core level absorption for unoccupied orbitals. Their experimental results focus on optical probes involving the C 1s core level, i.e. absorption via transitions from the C 1s level into unoccupied {pi}* and {sigma}* orbitals and emission involving transitions from occupied orbitals into a C 1s hole. Due to the simplicity of the C 1s level there exist clear selection rules. For example, only transitions to and from orbitals with p-character are dipole-allowed. These results on the p-projected density of states are compared with inverse photoemission and photoemission results, where the selection rules are less definitive. In addition, a first-principles quasiparticle calculation of the density of states is used to assign the orbital features. The spectra from C{sub 60} and C{sub 70} are still far from their infinite analog, i.e., graphite, which is also measured with the same techniques. In order to determine the effect of electron transfer onto C{sub 60}, as in superconducting alkali fullerides, the authors are studying resonant emission of C{sub 60}. An electron is placed in the lowest unoccupied molecular orbital (LUMO) by optical absorption from the C 1s level and the C 1s emission detected in the presence of this spectator electron.

  10. High-kinetic-energy photoemission spectroscopy of Ni at 1s : 6-eV satellite at 4 eV

    NASA Astrophysics Data System (ADS)

    Karis, O.; Svensson, S.; Rusz, J.; Oppeneer, P. M.; Gorgoi, M.; Schäfers, F.; Braun, W.; Eberhardt, W.; Mårtensson, N.

    2008-12-01

    Electron correlations are responsible for many profound phenomena in solid-state physics. A classical example is the 6-eV satellite in the photoelectron spectrum of Ni. Until now the satellite structure has only been investigated at the L shell and more shallow levels. Here we report a high-kinetic-energy photoemission spectroscopy (HIKE) investigation of Ni metal. We present 1s and 2p photoelectron spectra, obtained using excitation energies up to 12.6 keV. Our investigation demonstrates that the energy position of the satellite relative to the main line is different for the 1s and the 2p levels. In combination with electronic structure calculations, we show that this energy shift is attributed to unique differences in the core-valence coupling for the K and L2,3 shells in 3d transition metals, resulting in different screening of the core holes.

  11. (2R,1'S,2'R)- and (2S,1'S,2'R)-3-[2-Mono(di,tri)fluoromethylcyclopropyl]alanines and their incorporation into hormaomycin analogues

    PubMed Central

    Kozhushkov, Sergei I; Yufit, Dmitrii S; Grosse, Christian; Kaiser, Marcel

    2014-01-01

    Summary Efficient and scalable syntheses of enantiomerically pure (2R,1'S,2'R)- and (2S,1'S,2'R)-3-[2-mono(di,tri)fluoromethylcyclopropyl]alanines 9a–c, as well as allo-D-threonine (4) and (2S,3R)-β-methylphenylalanine (3), using the Belokon' approach with (S)- and (R)-2-[(N-benzylprolyl)amino]benzophenone [(S)- and (R)-10] as reusable chiral auxiliaries have been developed. Three new fluoromethyl analogues of the naturally occurring octadepsipeptide hormaomycin (1) with (fluoromethylcyclopropyl)alanine moieties have been synthesized and subjected to preliminary tests of their antibiotic activity. PMID:25550751

  12. The discontinuity near 1600 A in the spectra of DA white dwarfs

    NASA Technical Reports Server (NTRS)

    Wegner, G.

    1984-01-01

    Ultraviolet spectroscopic observations of two relatively cool DA white dwarfs, L481 - 60 (= WD 1544 - 37) and BPM 1266 ( = WD 2105 - 82), with the International Ultraviolet Explorer (IUE) satellite show a strong drop in their spectral energy distributions below 1600 A. Published model atmospheres and thier visual spectra suggest that these two stars have effective temperatures in the vicinity of 9,000-10,000 K, and it is proposed that the 1600 A feature could be due to the 342(1S) 3s2(1S) photoionization edge of Mg I.

  13. X-Ray Photoelectron Spectra of La{sub 0.67}Ca{sub 0.33}MnO{sub 3} Processed by EATPAH Technique

    SciTech Connect

    Mishra, D. K.; Dash, S.; Samantray, S.; Pradhan, S. K.; Das, J.; Roul, B. K.; Varma, S.

    2008-10-23

    La{sub 0.67}Ca{sub 0.33}MnO{sub 3}(LCMO) colossal magnetoresistance (CMR) materials were sintered to highly dense products by an extended arc thermal plasma assisted heating (EATPAH) technique within a short sintering time of 2.5 minutes as compared to conventional long range heating schedule (few hours of time). 2.5 minutes plasma sintered LCMO showed enhanced T{sub c}(272 K), which is closed to T{sub IM}(275 K)[1] as compared to the conventional sintered LCMO sample. Specimens are analyzed by X-ray Photoelectron Spectra (XPS) and electron probe microstructure analysis (EPMA) to get idea on elemental distribution and valence spectra of all the elements present in the specimen. The binding energy of La, Ca and Mn are analogous to the conventional sintered LCMO and to the reference spectra [2].

  14. OVI absorbers in SDSS spectra

    NASA Astrophysics Data System (ADS)

    Frank, Stephan

    We conducted a systematic search for signatures of the Intergalactic Medium (IGM) in Quasar spectra of the Sloan Digital Sky Survey (SDSS) Data Release 3 (DR3), focusing on finding intervening absorbers via detection of their O VI doublet. We present a search algorithm, and criteria for distinguishing candidates from spurious Lyman a forest lines. In addition, we compare our findings with simulations of the Lyman a forest in order to estimate the detectability of O VI doublets over various redshift intervals. We obtain a sample of 1866 O VI doublet candidates with rest-frame equivalent width >= 0.05 λ in 855 AGN spectra (out of 3702 objects with redshifts in the range accessible for O VI detection). This sample is subdivided into 3 groups according to the likelihood of being real and the potential for follow-up observation of the candidate. The group with the cleanest and most secure candidates is comprised of 145 candidates. 69 of these reside at a velocity separation >= 5000 km/s from the QSO, and can therefore be classified tentatively as intervening absorbers. Most of these absorbers have not been picked up by earlier, automated QSO absorption line detection algorithms. This sample increases the number of known O VI absorbers at redshifts beyond z abs >= 2.7 substantially. We propose to obtain observations of some of the candidates with the best signatures for O VI doublets with high signal-to-noise and high resolution in order to better constrain the physical state of the absorbers. We then focused on a subsample of 387 AGN sightlines with an average S/N >= 5: 0, allowing for the detection of absorbers above a rest-frame equivalent width limit of W r >= 0:19 ? A for the O VI 1032 λ component. Accounting for random interlopers mimicking an O VI doublet, we derive for the first time a secure lower limit for the redshift number density DN/Dz for redshifts z abs >= 2:8. With extensive Monte Carlo simulations we quantify the losses of absorbers due to blending

  15. GATA1s induces hyperproliferation of eosinophil precursors in Down syndrome transient leukemia

    PubMed Central

    Maroz, Aliaksandra; Stachorski, Lena; Emmrich, Stephan; Reinhardt, Katarina; Xu, Jian; Shao, Zhen; Käbler, Sebastian; Dertmann, Tobias; Hitzler, Johann; Roberts, Irene; Vyas, Paresh; Juban, Gaetan; Hennig, Christian; Hansen, Gesine; Li, Zhe; Orkin, Stuart; Reinhardt, Dirk; Klusmann, Jan-Henning

    2014-01-01

    Transient leukemia (TL) is evident in 5–10% of all neonates with Down syndrome (DS) and associated with N-terminal truncating GATA1-mutations (GATA1s). Here we report that TL cell clones generate abundant eosinophils in a substantial fraction of patients. Sorted eosinophils from patients with TL and eosinophilia carried the same GATA1s-mutation as sorted TL-blasts, consistent with their clonal origin. TL-blasts exhibited a genetic program characteristic of eosinophils and differentiated along the eosinophil lineage in vitro. Similarly, ectopic expression of Gata1s, but not Gata1, in wild-type CD34+-hematopoietic stem and progenitor cells induced hyperproliferation of eosinophil promyelocytes in vitro. While GATA1s retained the function of GATA1 to induce eosinophil genes by occupying their promoter regions, GATA1s was impaired in its ability to repress oncogenic MYC and the pro-proliferative E2F transcription network. ChIP-seq indicated reduced GATA1s occupancy at the MYC promoter. Knockdown of MYC, or the obligate E2F-cooperation partner DP1, rescued the GATA1s-induced hyperproliferative phenotype. In agreement, terminal eosinophil maturation was blocked in Gata1Δe2 knockin mice, exclusively expressing Gata1s, leading to accumulation of eosinophil precursors in blood and bone marrow. These data suggest a direct relationship between the N-terminal truncating mutations of GATA1 and clonal eosinophilia in DS patients. PMID:24336126

  16. Blocking the association of HDAC4 with MAP1S accelerates autophagy clearance of mutant Huntingtin.

    PubMed

    Yue, Fei; Li, Wenjiao; Zou, Jing; Chen, Qi; Xu, Guibin; Huang, Hai; Xu, Zhen; Zhang, Sheng; Gallinari, Paola; Wang, Fen; McKeehan, Wallace L; Liu, Leyuan

    2015-10-01

    Autophagy controls and executes the turnover of abnormally aggregated proteins. MAP1S interacts with the autophagy marker LC3 and positively regulates autophagy flux. HDAC4 associates with the aggregation-prone mutant huntingtin protein (mHTT) that causes Huntington's disease, and colocalizes with it in cytosolic inclusions. It was suggested HDAC4 interacts with MAP1S in a yeast two-hybrid screening. Here, we found that MAP1S interacts with HDAC4 via a HDAC4-binding domain (HBD). HDAC4 destabilizes MAP1S, suppresses autophagy flux and promotes the accumulation of mHTT aggregates. This occurs by an increase in the deacetylation of the acetylated MAP1S. Either suppression of HDAC4 with siRNA or overexpression of the MAP1S HBD leads to stabilization of MAP1S, activation of autophagy flux and clearance of mHTT aggregates. Therefore, specific interruption of the HDAC4-MAP1S interaction with short peptides or small molecules to enhance autophagy flux may relieve the toxicity of mHTT associated with Huntington's disease and improve symptoms of HD patients.

  17. Study of different filtering techniques applied to spectra from airborne gamma spectrometry

    SciTech Connect

    Wilhelm, Emilien; Gutierrez, Sebastien; Reboli, Anne; Menard, Stephanie; Nourreddine, Abdel-Mjid; Arbor, Nicolas

    2015-07-01

    One of the features of spectra obtained by airborne gamma spectrometry is low counting statistics due to the short acquisition time (1 s) and the large source-detector distance (40 m). It leads to considerable uncertainty in radionuclide identification and determination of their respective activities from the windows method recommended by the IAEA, especially for low-level radioactivity. The present work compares the results obtained with filters in terms of errors of the filtered spectra with the window method and over the whole gamma energy range. The results are used to determine which filtering technique is the most suitable in combination with some method for total stripping of the spectrum. (authors)

  18. Presence of monovalent oxygen anions in oxides demonstrated using X-ray photoelectron spectra

    SciTech Connect

    Wu, L. Q.; Li, Z. Z.; Tang, G. D. Qi, W. H.; Xue, L. C.; Ding, L. L.; Ge, X. S.; Li, S. Q.; Li, Y. C.

    2016-01-11

    The oxygen vacancy model has been used to explain the magnetic and electrical transport properties of dilute magnetic semiconductors and resistive switching. In particular, some authors have claimed that they found a symmetric peak corresponding to the oxygen vacancies in O1s photoelectron spectra. In this paper, using X-ray photoelectron spectra with argon ion etching, it is shown that this symmetric peak may also be interpreted as being related to O{sup 1−} anions, rather than to oxygen vacancies.

  19. {upsilon}(1S){yields}{gamma}f{sub 2}(1270) decay

    SciTech Connect

    Li Bingan

    2009-12-01

    Decay {upsilon}(1S){yields}{gamma}f{sub 2}(1270) is studied by an approach in which the tensor meson, f{sub 2}(1270), is strongly coupled to gluons. Besides the strong suppression of the amplitude {upsilon}(1S){yields}{gamma}gg, gg{yields}f{sub 2} by the mass of the b-quark, d-wave dominance in {upsilon}(1S){yields}{gamma}f{sub 2}(1270) is revealed from this approach, which provides a large enhancement. The combination of these two factors leads to larger B({upsilon}(1S){yields}{gamma}f{sub 2}(1270)). The decay rate of {upsilon}(1S){yields}{gamma}f{sub 2}(1270) and the ratios of the helicity amplitudes are obtained and they are in agreement with the data.

  20. In Situ SR-XPS Observation of Ni-Assisted Low-Temperature Formation of Epitaxial Graphene on 3C-SiC/Si

    NASA Astrophysics Data System (ADS)

    Hasegawa, Mika; Sugawara, Kenta; Suto, Ryota; Sambonsuge, Shota; Teraoka, Yuden; Yoshigoe, Akitaka; Filimonov, Sergey; Fukidome, Hirokazu; Suemitsu, Maki

    2015-10-01

    Low-temperature (~1073 K) formation of graphene was performed on Si substrates by using an ultrathin (2 nm) Ni layer deposited on a 3C-SiC thin film heteroepitaxially grown on a Si substrate. Angle-resolved, synchrotron-radiation X-ray photoemission spectroscopy (SR-XPS) results show that the stacking order is, from the surface to the bulk, Ni carbides(Ni3C/NiCx)/graphene/Ni/Ni silicides (Ni2Si/NiSi)/3C-SiC/Si. In situ SR-XPS during the graphitization annealing clarified that graphene is formed during the cooling stage. We conclude that Ni silicide and Ni carbide formation play an essential role in the formation of graphene.

  1. XPS and ToF-SIMS analysis of natural rubies and sapphires heat-treated in a reducing (5 mol% H 2/Ar) atmosphere

    NASA Astrophysics Data System (ADS)

    Achiwawanich, S.; James, B. D.; Liesegang, J.

    2008-12-01

    Surface effects on Mong Hsu rubies and Kanchanaburi sapphires after heat treatment in a controlled reducing atmosphere (5 mol% H 2/Ar) have been investigated using advanced surface science techniques including X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Visual appearance of the gemstones is clearly affected by the heat treatment in a reducing atmosphere. Kanchanaburi sapphires, in particular, exhibit Fe-containing precipitates after the heat treatment which have not been observed in previous studies under an inert atmosphere. Significant correlation between changes in visual appearance of the gemstones and variations in surface concentration of trace elements, especially Ti and Fe are observed. The XPS and ToF-SIMS results suggest that; (1) a reducing atmosphere affects the oxidation state of Fe; (2) dissociation of Fe-Ti interaction may occur during heat treatment.

  2. XPS study of surface composition of polycrystalline CuxCo3- xO4 (0⩽ x<1) obtained by thermal decomposition of nitrate mixtures

    NASA Astrophysics Data System (ADS)

    Angelov, S.; Tyuliev, G.; Marinova, Ts.

    1987-02-01

    The composition of surface layers of spinel oxides CuxCo3- xO4 (0⩽ x<1), obtained by thermal decomposition of nitrate mixtures, has been studied by means of XPS or ESCA. The surface layer sampled by XPS cannot be described by the bulk formula: the density of Co cations is lower than in the bulk and correspondingly, the oxygen-to-metal ratio and copper-to-cobalt ratio are higher than the mean values for the bulk. The increase in the copper content is accompanied with a decrease of the oxygen-to-metal ratio and an increase in the amount of O - and/or OH - species on the surface of the mixed spinels.

  3. Adsorption and reaction of methanethiol on the Ru(0 0 0 1)- p(2 × 2)O surface: A TPD and XPS study

    NASA Astrophysics Data System (ADS)

    Chang, Zhipeng; Tang, W. H.

    2007-05-01

    Methanethiol adsorbed on Ru(0 0 0 1)- p(2 × 2)O has been studied by TPD and XPS. The dissociation of methanethiol to methylthiolate and hydrogen at 90 K is evidenced by the observation of hydroxyl and water. The saturation coverage of methylthiolate is ˜0.15 ML, measured by both XPS and TPD. A detailed analysis suggests that only the hcp-hollow sites have been occupied. Upon annealing the surface, water and hydroxyl desorb from the surface at ˜210 K. Methylthiolate decomposes to methyl radical and atomic sulphur via C-S cleavage between 350 and 450 K. Some methyl radicals (0.05 ML) have been transferred to Ru atoms before they decompose to carbon and hydrogen. The rest of methyl radicals desorb as gaseous phase. No evidence for the transfer of methyl radical to surface oxygen has been found.

  4. XPS and STEM Study of the Interface Formation between Ultra-Thin Ru and Ir OER Catalyst Layers and Perylene Red Support Whiskers

    SciTech Connect

    Atanasoska, Liliana; Cullen, David A; Hester, Amy E; Atanasoski, Radoslav

    2013-01-01

    The interface formation between perylene red (PR) and ruthenium or iridium OER catalysts has been studied systematically by XPS and STEM. The OER catalyst over-layers with thicknesses ranging from ~0.1 to ~50 nm were vapor deposited onto PR ex-situ. As seen by STEM, Ru and Ir form into nanoparticles, which agglomerate with increased loading. XPS data show a strong interaction between Ru and PR. Ir also interacts with PR although not to the extent seen for Ru. At low coverages, the entire Ru deposit is in the reacted state while a small portion of the deposited Ir remains metallic. Ru and Ir bonding occur at the PR carbonyl sites as evidenced by the attenuation of carbonyl photoemission and the emergence of new peak assigned to C-O single bond. The curve fitting analysis and the derived stoichiometry indicates the formation of metallo-organic bonds. The co-existence of oxide bonds is also apparent.

  5. Blind extraction of exoplanetary spectra

    NASA Astrophysics Data System (ADS)

    Morello, Giuseppe; Waldmann, Ingo P.; Tinetti, Giovanna

    2016-06-01

    In the last decade, remote sensing spectroscopy enabled characterization of the atmospheres of extrasolar planets. Transmission and emission spectra of tens of transiting exoplanets have been measured with multiple instruments aboard Spitzer and Hubble Space Telescopes as well as ground-based facilities, revealing the presence of atomic, ionic and molecular species in their atmospheres, and constraining their temperature and pressure profiles.Early analyses were somehow heuristic both in measuring the spectra and in their interpretation, leading to some controversies in the literature.A photometric precision of 0.01% is necessary to detect the atmospheric spectral modulations. Current observatories, except Kepler, were not designed to achieve this precision. Data reduction is necessary to minimize the effect of instrument systematics in order to achieve the target precision. In the past, parametric models have extensively been used by most teams to remove correlated noise with the aid of auxiliary information of the instrument, the so-called optical state vectors (OSVs). Such OSVs can include inter- and intra-pixel position of the star or its spectrum, instrument temperatures and inclinations, and/or other parameters. In some cases, different parameterizations led to discrepant results.We recommend the use of blind non-parametric data detrending techniques to overcome those issues. In particular, we adopt Independent Component Analysis (ICA), i.e. a blind source separation (BSS) technique to disentangle the multiple instrument systematics and astrophysical signals in transit/eclipse light curves. ICA does not require a model for the systematics, and for this reason, it can be applied to any instrument with little changes, if any. ICA-based algorithms have been applied to Spitzer/IRAC and synthetic observations in photometry (Morello et al. 2014, 2015, 2016; Morello 2015) and to Hubble/NICMOS and Spitzer/IRS in spectroscopy (Waldmann 2012, 2014, Waldmann et al. 2013

  6. The novel function of JADE1S in cytokinesis of epithelial cells

    PubMed Central

    Siriwardana, Nirodhini S; Meyer, Rosana D; Panchenko, Maria V

    2015-01-01

    JADE1 belongs to a small family of PHD zinc finger proteins that interacts with histone acetyl transferase (HAT) HBO1 and is associated with chromatin. We recently reported JADE1 chromatin shuttling and phosphorylation during G2/M to G1 transition, which was sensitive to Aurora A inhibition. In the current study we examined mechanisms of the cell cycle regulation by the small isoform of JADE1 protein, JADE1S, and report data showing that JADE1S has a novel function in the regulation of cytokinesis. Using FACS assays, we show that, JADE1S depletion facilitated rates of G1-cells accumulation in synchronously dividing HeLa cell cultures. Depletion of JADE1S protein in asynchronously dividing cells decreased the proportion of cytokinetic cells, and increased the proportion of multi-nuclear cells, indicative of premature and failed cytokinesis. In contrast, moderate overexpression of JADE1S increased the number of cytokinetic cells in time- and dose- dependent manner, indicating cytokinetic delay. Pharmacological inhibition of Aurora B kinase resulted in the release of JADE1S-mediated cytokinetic delay and allowed progression of abscission in cells over-expressing JADE1S. Finally, we show that JADE1S protein localized to centrosomes in interphase and mitotic cells, while during cytokinesis JADE1S localized to the midbody. Neither JADE1L nor partner of JADE1, HAT HBO1 was localized to the centrosomes or midbodies. Our study identifies the novel role for JADE1S in regulation of cytokinesis and suggests function in Aurora B kinase-mediated cytokinesis checkpoint. PMID:26151225

  7. 1s22p3 and 1s22s23l, l = s,p,d, excited states of boron isoelectronic series from explicitly correlated wave functions.

    PubMed

    Gálvez, F J; Buendía, E; Sarsa, A

    2005-07-15

    For some members of the boron isoelectronic series and starting from explicitly correlated wave functions, six low-lying excited states have been studied. Three of them arise from the 1s(2)2p(3) configuration, and the other three from the 1s(2)2s(2)3l, l = s,p,d, configurations. This work follows a previous one on both the 1s(2)2s(2)2p-(2)P ground state and the four excited states coming from the 1s(2)2s2p(2) configuration. Energies, one- and two-body densities in position space and some other two-body properties in position and momentum spaces have been obtained. A systematic analysis of the energetic ordering of the states as a function of the total orbital angular momentum and spin is performed in terms of the electron-nucleus and electron-electron potential energies and the role of the angular correlation is discussed. All calculations have been carried out by using the Monte Carlo algorithm.

  8. Determination of the de-excitation probability of argon metastable (1s5 and 1s3) atoms on aluminum, stainless steel, silicon, quartz and Pyrex surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Zhen-Bin; Li, Jiang-Tao; Zhu, Xi-Ming; Pu, Yi-Kang

    2015-03-01

    The de-excitation probability of argon 1s5 and 1s3 metastable atoms on aluminum (alloy 2024), stainless steel (304), silicon (100), quartz (JGS1) and Pyrex surfaces is measured with a low pressure (1-5 mTorr) pulsed capacitively coupled plasma. The de-excitation probability is deduced from the loss rate of the metastable atoms in the late afterglow, which is obtained from the temporal evolution of the metastable atom density measured by laser absorption. Under the low pressure condition, the loss of the metastable atoms is mainly due to volume diffusion and de-excitation on the surface. The measured de-excitation probability for both Ar*(1s5) and Ar*(1s3) atoms ranges from 0.74 to 0.88 on these five materials, with an uncertainty of ±0.11. The measured probabilities on the Pyrex surface are in good agreement with those reported in previous work, and those on aluminum, stainless steel, silicon and quartz surfaces are reported here for the first time.

  9. XPS investigation of thionyl chloride action on iron phthalocyanines and naphthalocyanines and on hydrogen phthalocyanine — Correlations with the activity of Li/SOCl 2 cells

    NASA Astrophysics Data System (ADS)

    Savy, Michel; Riga, Joseph; Verbist, Jacques J.

    1989-03-01

    X-ray photoelectron spectroscopic measurements have been performed on iron phthalocyanines and naphthalocyanines, and hydrogen phthalocyanine powders, after dissolution in SOCl 2 and reprecipitation. The comparison of XPS results with catalytic activities observed in the lithium/thionyl chloride batteries during their discharge underlines the rôles of the central ion oxidation facility and ligand stability in the electrocatalysis of SOCl 2 reduction.

  10. Application of maximum-entropy spectral estimation to deconvolution of XPS data. [X-ray Photoelectron Spectroscopy

    NASA Technical Reports Server (NTRS)

    Vasquez, R. P.; Klein, J. D.; Barton, J. J.; Grunthaner, F. J.

    1981-01-01

    A comparison is made between maximum-entropy spectral estimation and traditional methods of deconvolution used in electron spectroscopy. The maximum-entropy method is found to have higher resolution-enhancement capabilities and, if the broadening function is known, can be used with no adjustable parameters with a high degree of reliability. The method and its use in practice are briefly described, and a criterion is given for choosing the optimal order for the prediction filter based on the prediction-error power sequence. The method is demonstrated on a test case and applied to X-ray photoelectron spectra.

  11. Interpretation of Nitroindolinospirobenzothiopyran Vibrational Spectra

    NASA Astrophysics Data System (ADS)

    Gladkov, L. L.; Khamchukov, Yu. D.; Lyubimov, A. V.

    2016-05-01

    The structures of four possible stereoisomers of the closed form of photochromic nitroindolinospirobenzothiopyran (NISTP) {1',3'-dihydro-1',3',3'-trimethyl-6-nitrospiro[2H-1-benzothiopyran-2,2'-(2H)-indoline]} were determined by the DFT method. The geometry of the most stable isomer was defined. Nitro-substitution changes mainly the lengths of bonds formed by S and N with spiro-atom Cs. According to the calculations, the CsS bond changes most and lengthens by 0.019 Å. It is shown that the S atom has large displacement amplitudes in normal modes assigned to Raman lines at 230, 285, 360, and 575 cm-1 and weak IR bands at 467 and 577 cm-1. Oscillations involving the nitro group are very active in Raman and IR spectra. Their frequencies are slightly lower than similar frequencies of nitrobenzene and nitroindolinospirobenzopyran, indicating a higher degree of vibrational coupling of the NO2 group with the NISTP molecular skeleton.

  12. Reflectance spectra of subarctic lichens

    NASA Technical Reports Server (NTRS)

    Petzold, Donald E.; Goward, Samuel N.

    1988-01-01

    Lichens constitute a major portion of the ground cover of high latitude environments, but little has been reported concerning their in situ solar spectral reflectance properties. Knowledge of these properties is important for the interpretation of remotely sensed observations from high latitude regions, as well as in studies of high latitude ecology and energy balance climatology. The spectral reflectance of common boreal vascular plants is similar to that of vascular plants of the midlatitudes. The dominant lichens, in contrast, display variable reflectance patterns in visible wavelengths. The relative reflectance peak at 0.55 microns, common to green vegetation, is absent or indistinct in spectra of pervasive boreal forest and tundra lichens, despite the presence of chlorophyll in the inner algal cells. Lichens of the dominant genus, Cladina, display strong absorption of ultraviolet energy and short-wavelength blue light relative to their absorption in other visible wavelengths. Since the Cladinae dominate both the surface vegetation in open woodlands of the boreal forest and the low arctic tundra, their unusual spectral reflectance patterns will enable accurate monitoring of the boreal forest-tundra ecotone and detection of its vigor and movement in the future.

  13. XPS investigations of the proton exchange membrane fuel cell active layers aging: Characterization of the mitigating role of an anodic CO contamination on cathode degradation

    NASA Astrophysics Data System (ADS)

    Parry, Valérie; Berthomé, Grégory; Joud, Jean-Charles; Lemaire, Olivier; Franco, Alejandro A.

    2011-03-01

    This paper presents new results from XPS quantitative characterizations of cathode catalyst layers aged in a PEMFC with an anode operated under pure hydrogen and air and with 5 ppm CO contaminated hydrogen. Both oxygen rich and oxygen poor zones of the cathode catalyst layer were analyzed in order to show up heterogeneous degradation linked with gas distribution. The detailed chemical XPS analysis of the aged samples demonstrates in particular that in our operating conditions, the catalyst layer aging is mainly attributed to the oxidation of the carbon catalyst-support. A loss of the Nafion® ionomer in the cathode is also highlighted by XPS. Furthermore, the characterization of the cathodic catalyst layer chemical composition when CO is introduced in the anode side shows that the catalyst layer degradation is lower. These results are in agreement with the experimental-modeling work by Franco et al. [1] demonstrating that anodic CO contamination decreases the reverse proton pumping effect between the cathode and the anode and enhances the PEMFC durability.

  14. Structural, XPS and magnetic studies of pulsed laser deposited Fe doped Eu{sub 2}O{sub 3} thin film

    SciTech Connect

    Kumar, Sandeep; Prakash, Ram; Choudhary, R.J.; Phase, D.M.

    2015-10-15

    Highlights: • Growth of Fe doped Eu{sub 2}O{sub 3} thin films by PLD. • XRD and Raman’s spectroscopy used for structure confirmation. • The electronic states of Eu and Fe are confirmed by XPS. • Magnetic properties reveals room temperature magnetic ordering in deposited film. - Abstract: Fe (4 at.%) doped europium (III) oxide thin film was deposited on silicon (1 0 0) substrate by pulsed laser deposition technique. Structural, spectral and magnetic properties were studied by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and magnetization measurements. XRD and Raman spectroscopy reveal that the grown film is single phased and belongs to the cubic structure of Eu{sub 2}O{sub 3}. XPS study of the Eu{sub 1.92}Fe{sub 0.08}O{sub 3} film shows that Fe exists in Fe{sup 3+} ionic state in the film. The film exhibits magnetic ordering at room temperature.

  15. Interface and plasma damage analysis of PEALD TaCN deposited on HfO2 for advanced CMOS studied by angle resolved XPS and C-V

    NASA Astrophysics Data System (ADS)

    Piallat, Fabien; Beugin, Virginie; Gassilloud, Remy; Dussault, Laurent; Pelissier, Bernard; Leroux, Charles; Caubet, Pierre; Vallée, Christophe

    2014-06-01

    Plasma enhanced atomic layer deposition (PEALD) TaCN deposited on HfO2 was studied by X-ray photoelectron spectroscopy (XPS) to understand the reactions taking place at the interface and connect them with C-V electrical characteristics of MOS devices. Moreover, angular resolved XPS (AR-XPS) was used for composition depth profiling of TaCN/HfO2/SiO2/Si stacks. Clear oxidation of the metal electrode through Tasbnd O bonding formation and migration of N in the dielectric with Hfsbnd N are shown. These modifications of chemical bonding give an insight on the electrical results. Low equivalent oxide thicknesses (EOT), as low as 0.89 nm and current leakage improvement by more than 5 decades, are observed for deposition with low plasma power and can be related to HfN content in HfO2 layer. The increase of plasma power used for TaCN deposition results in densification of the layer and promotes the creation of TaC in TaCN material. However H2 plasma has an impact on HfO2 with a reduction and scattering of the measured current leak gain. TaCN/HfO2 interface is also impacted with further creation of TaOx, leading to an increase of EOT when plasma power is increased. Based on these findings, reaction mechanisms with the corresponding Gibbs free energy are proposed.

  16. X-ray spectra of supernova remnants

    NASA Technical Reports Server (NTRS)

    Szymkowiak, A. E.

    1985-01-01

    X-ray spectra were obtained from fields in three supernova remnants with the solid state spectrometer of the HEAO 2 satellite. These spectra, which contain lines from K-shell transitions of several abundant elements with atomic numbers between 10 and 22, were compared with various models, including some of spectra that would be produced by adiabatic phase remnants when the time-dependence of the ionization is considered.

  17. A Bayesian method for analysing relaxation spectra

    NASA Astrophysics Data System (ADS)

    Ciocci Brazzano, L.; Pellizza, L. J.; Matteo, C. L.; Sorichetti, P. A.

    2016-01-01

    The knowledge of electrical and mechanical properties of material, relies on a precise analysis of the relaxation spectra. We explore the ability of a Bayesian method to achieve an accurate estimation of spectral parameters. We implemented a parallel-tempering Markov-chain Monte Carlo algorithm and used it to fit simulated and measured spectra. An exhaustive testing of the code shows that it presents an extremely good performance, accurately fitting complex spectra under strong noise and overlapping components. We conclude that this technique is quite suitable for relaxation spectra analysis, complementing classical methods.

  18. ALIEN: A nebular spectra analysis software

    NASA Astrophysics Data System (ADS)

    Cook, R.; Vazquez, R.

    2000-11-01

    A new C-coded software, designed to analyze nebular spectra, is presented. T his software is able to read the fluxes of the most important ions directly from IRAF's output file (splot.log). Spectra can be dereddened using the Balmer lines ratio and the Seaton's extinction law. Electron temperature and density, as well as ionic abundances by number are estimated by means of numeric calculations based on the five-level atom model. The dereddened spectra and the table containing the ionic abundances can be saved in a LaTex formatted file. This software has been initially designed to work with a low dispersion spectra.

  19. Near-Infrared Spectra of Uranian Satellites

    NASA Astrophysics Data System (ADS)

    Venturini, C. C.; Lynch, D. K.; Rudy, R. J.; Mazuk, S.; Puetter, R. C.

    2001-05-01

    We present 0.8 to 2.5 micron spectra taken on June 21 & 22, 1998 UT of the Uranian satellites Miranda, Titania, Ariel, Oberon, and Umbriel. The spectra were taken using The Aerospace Corporation's Near-Infrared Imaging Spectragraph (NIRIS) on the University of California's Lick Observatory 3 meter Shane telescope. These spectra will be compared with previous work including Brown, R.H. and Cruikshank, D.P. (1983) as well as more recent spectra and analysis by Grundy, W. et al. (1999). Support for this research was provided by The Aerospace Corporation's Independent Research and Development Program.

  20. [Describing language of spectra and rough set].

    PubMed

    Qiu, Bo; Hu, Zhan-yi; Zhao, Yong-heng

    2002-06-01

    It is the traditional way to analyze spectra by experiences in astronomical field. And until now there has never been a suitable theoretical frame to describe spectra, which is may be owing to small spectra datasets that astronomers can get by low-level instruments. With the high-speed development of telescopes, especially on behalf of LAMOST, a large telescope which can collect more than 20,000 spectra in an observing night, spectra datasets are becoming larger and larger very fast. Facing these voluminous datasets, the traditional spectra-processing way simply depending on experiences becomes unfit. In this paper, we develop a brand-new language--describing language of spectra (DLS) to describe spectra of celestial bodies by defining BE (Basic element). And based on DLS, we introduce the method of RSDA (Rough set and data analysis), which is a technique of data mining. By RSDA we extract some rules of stellar spectra, and this experiment can be regarded as an application of DLS.

  1. Differential phenotypic and functional properties of liver-resident NK cells and mucosal ILC1s.

    PubMed

    Tang, Ling; Peng, Hui; Zhou, Jing; Chen, Yongyan; Wei, Haiming; Sun, Rui; Yokoyama, Wayne M; Tian, Zhigang

    2016-02-01

    Group 1 innate lymphoid cells (ILCs) consist of conventional natural killer (cNK) cells, tissue-resident NK cells and mucosal ILC1s. Recently identified liver-resident NK cells, which can mount contact hypersensitivity responses, and mucosal ILC1s that are involved in pathogenesis of colitis are distinct from cNK cells in several aspects, but the issue of how they are related to each other has not been clearly clarified. Here, we show that liver-resident NK cells and mucosal ILC1s have different phenotypes, as evidenced by distinct expression patterns of homing-associated molecules. Moreover, mucosal ILC1s exhibit tissue residency akin to liver-resident NK cells. Importantly, liver-resident NK cells express relative high levels of cytotoxic effector molecules, which are poorly expressed by mucosal ILC1s, and exhibit stronger cytotoxic activity compared with mucosal ILC1s. These results demonstrate differential phenotypic and functional characteristics of liver-resident NK cells and mucosal ILC1s, shedding new light on the diversity of ILC family.

  2. Measurement of the 1S-2S Frequency in Atomic Hydrogen

    NASA Astrophysics Data System (ADS)

    Hildum, Edward Ames

    A first precise measurement of the 1S-2S energy interval in atomic hydrogen has been obtained by observing the 1S-2S transition in an atomic beam by pulsed Doppler -free two-photon spectroscopy and using an interferometrically calibrated line of ('130)Te(,2) at 486 nm as the reference. The measured 1S-2S frequency is 2 466 061 395.6(4.9) MHz. With the calculated 1S Lamb shift, the 1S-2S frequency yields a value for the Rydberg constant, R(,(INFIN)) = 109 737.314 92(22) cm('-1), which is not in good agreement with the most recent previously measured value, 109 737.315 44(11) cm('-1), obtained by S. R. Amin et al.('16) It is, however, in good agreement with a previous Rydberg value, 109 737.315 04(32) cm('-1), measured by J. E. M. Goldsmith('17). If the Rydberg constant is taken as given, the 1S-2S frequency determines a value for the 1S Lamb shift. With Amin's Rydberg, the measured Lamb shift is 8161.0(5.4) MHz, in poor agreement with the theoretical value of 8149.43(8) MHz. With Goldsmith's Rydberg, the measured Lamb shift is 8151.0(8.7) MHz, in good agreement with theory.

  3. Off-resonance photoemission dynamics studied by recoil frame F1s and C1s photoelectron angular distributions of CH{sub 3}F

    SciTech Connect

    Stener, M. Decleva, P.; Mizuno, T.; Yagishita, A.; Yoshida, H.

    2014-01-28

    F1s and C1s photoelectron angular distributions are considered for CH{sub 3}F, a molecule which does not support any shape resonance. In spite of the absence of features in the photoionization cross section profile, the recoil frame photoelectron angular distributions (RFPADs) exhibits dramatic changes depending on both the photoelectron energy and polarization geometry. Time-dependent density functional theory calculations are also given to rationalize the photoionization dynamics. The RFPADs have been compared with the theoretical calculations, in order to assess the accuracy of the theoretical method and rationalize the experimental findings. The effect of finite acceptance angles for both ionic fragments and photoelectrons has been included in the calculations, as well as the effect of rotational averaging around the fragmentation axis. Excellent agreement between theory and experiment is obtained, confirming the good quality of the calculated dynamical quantities (dipole moments and phase shifts)

  4. 7. JOB NO. 1347G, SHEET 1S, 1929, OIL HOUSE; FORD ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. JOB NO. 1347-G, SHEET 1S, 1929, OIL HOUSE; FORD MOTOR COMPANY; PLANS, SECTIONS AND DETAILS - Ford Motor Company Long Beach Assembly Plant, Oil House, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

  5. Observation of Upsilon(2S)-->etaUpsilon(1S) and search for related transitions.

    PubMed

    He, Q; Insler, J; Muramatsu, H; Park, C S; Thorndike, E H; Yang, F; Artuso, M; Blusk, S; Khalil, S; Li, J; Mountain, R; Nisar, S; Randrianarivony, K; Sultana, N; Skwarnicki, T; Stone, S; Wang, J C; Zhang, L M; Bonvicini, G; Cinabro, D; Dubrovin, M; Lincoln, A; Naik, P; Rademacker, J; Asner, D M; Edwards, K W; Reed, J; Briere, R A; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L; Alexander, J P; Cassel, D G; Duboscq, J E; Ehrlich, R; Fields, L; Galik, R S; Gibbons, L; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Hunt, J M; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Ledoux, J; Mahlke-Krüger, H; Mohapatra, D; Onyisi, P U E; Patterson, J R; Peterson, D; Riley, D; Ryd, A; Sadoff, A J; Shi, X; Stroiney, S; Sun, W M; Wilksen, T; Athar, S B; Patel, R; Yelton, J; Rubin, P; Eisenstein, B I; Karliner, I; Mehrabyan, S; Lowrey, N; Selen, M; White, E J; Wiss, J; Mitchell, R E; Shepherd, M R; Besson, D; Pedlar, T K; Xavier, J V; Cronin-Hennessy, D; Gao, K Y; Hietala, J; Kubota, Y; Klein, T; Lang, B W; Poling, R; Scott, A W; Zweber, P; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Libby, J; Martin, L; Powell, A; Wilkinson, G; Ecklund, K M; Love, W; Savinov, V; Mendez, H; Ge, J Y; Miller, D H; Shipsey, I P J; Xin, B; Adams, G S; Anderson, M; Cummings, J P; Danko, I; Hu, D; Moziak, B; Napolitano, J

    2008-11-07

    We report the first observation of Upsilon(2S)-->etaUpsilon(1S), with a branching fraction B=(2.1(-0.6)+0.7(stat)+/-0.3(syst)) x 10(-4) and a statistical significance 5.3sigma. Data were acquired with the CLEO III detector at the CESR e+e(-) symmetric collider. This is the first process observed involving a b-quark spin flip. For related transitions, 90% confidence limits in units of 10(-4) are B(Upsilon(2S)-->pi0Upsilon(1S)) < 1.8, B(Upsilon(3S)-->etaUpsilon(1S)) < 1.8, B(Upsilon(3S)-->pi0Upsilon(1S)) < 0.7, and B(Upsilon(3S)-->pi0Upsilon(2S)) < 5.1.

  6. Highly selective and potent agonists of sphingosine-1-phosphate 1 (S1P1) receptor.

    PubMed

    Vachal, Petr; Toth, Leslie M; Hale, Jeffrey J; Yan, Lin; Mills, Sander G; Chrebet, Gary L; Koehane, Carol A; Hajdu, Richard; Milligan, James A; Rosenbach, Mark J; Mandala, Suzanne

    2006-07-15

    Novel series of sphingosine-1-phosphate (S1P) receptor agonists were developed through a systematic SAR aimed to achieve high selectivity for a single member of the S1P family of receptors, S1P1. The optimized structure represents a highly S1P1-selective and efficacious agonist: S1P1/S1P2, S1P1/S1P3, S1P1/S1P4>10,000-fold, S1P1/S1P5>600-fold, while EC50 (S1P1) <0.2 nM. In vivo experiments are consistent with S1P1 receptor agonism alone being sufficient for achieving desired lymphocyte-lowering effect.

  7. 5. SWITCH TOWER AND JUNCTION OF S.A.R. #1 & S.A.R. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. SWITCH TOWER AND JUNCTION OF S.A.R. #1 & S.A.R. #2 TRANSMISSION LINES, MARCH 7, 1916. SCE drawing no. 4932. - Santa Ana River Hydroelectric System, Transmission Lines, Redlands, San Bernardino County, CA

  8. Autophagy enhanced by microtubule- and mitochondrion-associated MAP1S suppresses genome instability and hepatocarcinogenesis.

    PubMed

    Xie, Rui; Wang, Fen; McKeehan, Wallace L; Liu, Leyuan

    2011-12-15

    Dysfunctional autophagy is associated with tumorigenesis; however, the relationship between the two processes remains unclear. In the present study, we showed that MAP1S levels immediately become elevated in response to diethylnitrosamine-induced or genome instability-driven metabolic stress in a murine model of hepatocarcinoma. Upregulation of MAP1S enhanced autophagy to remove aggresomes and dysfunctional organelles that trigger DNA double-strand breaks and genome instability. The early accumulation of an unstable genome before signs of tumorigenesis indicated that genome instability caused tumorigenesis. After tumorigenesis, tumor development triggered the activation of autophagy to reduce genome instability in tumor foci. We, therefore, conclude that an increase in MAP1S levels triggers autophagy to suppress genome instability such that both the incidence of diethylnitrosamine-induced hepatocarcinogenesis and malignant progression are suppressed. Taken together, the data establish a link between MAP1S-enhanced autophagy and suppression of genomic instability and tumorigenesis.

  9. Lepton Universality Test in Upsilon(1S) Decays at BaBar

    SciTech Connect

    Guido, Elisa; /Genoa U. /INFN, Genoa

    2012-04-10

    Using a sample of 122 million {Upsilon}(3S) decays collected with the BABAR detector at the PEP-II asymmetric energy collider at the SLAC National Accelerator Laboratory, we measure the ratio R{sub {tau}{mu}} = BR({Upsilon}(1S) {yields} {tau}{sup +}{tau}{sup -})/BR({Upsilon}(1S) {yields} {mu}{sup +}{mu}{sup -}); the measurement is intended as a test of lepton universality and as a possible search for a light pseudoscalar Higgs boson in Next to Minimal Supersymmetric Standard Model (NMSSM) scenarios. Such a boson could appear in a deviation of the ratio R{sub {tau}{mu}} from the Standard Model expectation, that is 1, except for small lepton mass corrections. The analysis exploits the decays {Upsilon}(3S) {yields} {Upsilon}(1S){pi}{sup +}{pi}{sup -}, {Upsilon}(1S) {yields} l{sup +}l{sup -}, where l = {mu},{tau}.

  10. Resolution enhancement in second-derivative spectra.

    PubMed

    Czarnecki, Mirosław A

    2015-01-01

    Derivative spectroscopy is a powerful tool for the resolution enhancement in infrared, near-infrared, Raman, ultraviolet-visible, nuclear magnetic resonance, electron paramagnetic resonance, and fluorescence spectroscopy. Despite its great significance in analytical chemistry, not all aspects of the applications of this method have been explored as yet. This is the first systematic study of the parameters that influence the resolution enhancement in the second derivative spectra. The derivative spectra were calculated with the Savitzky-Golay method with different window size (5, 15, 25) and polynomial order (2, 4). The results obtained in this work show that the resolution enhancement in the second derivative spectra strongly depends on the data spacing in the original spectra, window size, polynomial order, and peak profile. As shown, the resolution enhancement is related to variations in the width of the peaks upon the differentiation. The present study reveals that in order to maximize the separation of the peaks in the second derivative spectra, the original spectra should be recorded at high resolution and differentiated using a small window size and high polynomial order. However, working with the real spectra one has to compromise between the noise reduction and optimization of the resolution enhancement in the second derivative spectra.

  11. Spectra of the Jovian ring and Amalthea

    NASA Technical Reports Server (NTRS)

    Neugebauer, G.; Becklin, E. E.; Jewitt, D. C.; Danielson, G. E.; Terrile, R. J.

    1981-01-01

    Measurements made between 0.887 and 2.4 microns demonstrate that the Jovian ring and Amalthea have similar reflection spectra. The spectra, in particular the ratio of the 0.9- to 2.2-micron reflectivities, are inconsistent with those expected from water, ammonia, or methane frosts, but are consistent with reflection from large rock bodies.

  12. Leptonic decay of the ϒ(1S) meson at third order in QCD.

    PubMed

    Beneke, Martin; Kiyo, Yuichiro; Marquard, Peter; Penin, Alexander; Piclum, Jan; Seidel, Dirk; Steinhauser, Matthias

    2014-04-18

    We present the complete next-to-next-to-next-to-leading order short-distance and bound-state QCD correction to the leptonic decay rate Γ(ϒ(1S)→ℓ+ℓ-) of the lowest-lying spin-1 bottomonium state. The perturbative QCD prediction is compared to the measurement Γ(ϒ(1S)→e+e-)=1.340(18)  keV.

  13. The interaction of atomic oxygen with copper: An XPS, AES, XRD, optical transmission, and stylus profilometry study

    NASA Technical Reports Server (NTRS)

    Raikar, Ganesh N.; Gregory, John C.; Christl, Ligia C.; Peters, Palmer N.

    1993-01-01

    The University of Alabama in Huntsville (UAH) experiment A-0114 was designed to study the reaction of material surfaces with low earth orbits (LEO) atmospheric oxygen. The experiment contained 128 one-inch circular samples; metals, polymers, carbons, and semiconductors. Half of these samples were exposed on the front of the Long Duration Exposure Facility (LDEF) and remaining on the rear. Among metal samples, copper has shown some interesting new results. There were two forms of copper samples: a thin film sputter-coated on fused silica and a solid piece of OFHC copper. They were characterized by x-ray and Auger electron spectroscopies, x-ray diffraction, and high resolution profilometry. Cu 2p core level spectra were used to demonstrate the presence of Cu2O and CuO and to determine the oxidation states.

  14. Charging of ionic liquid surfaces under X-ray irradiation: the measurement of absolute binding energies by XPS.

    PubMed

    Villar-Garcia, Ignacio J; Smith, Emily F; Taylor, Alasdair W; Qiu, Fulian; Lovelock, Kevin R J; Jones, Robert G; Licence, Peter

    2011-02-21

    Ionic liquid surfaces can become electrically charged during X-ray photoelectron spectroscopy experiments, due to the flux of photoelectrons leaving the surface. This causes a shift in the measured binding energies of X-ray photoelectron peaks that depends on the magnitude of the surface charging. Consequently, a charge correction method is required for ionic liquids. Here we demonstrate the nature and extent of surface charging in ionic liquids and model it using chronopotentiometry. We report the X-ray photoelectron spectra for a range of imidazolium based ionic liquids and investigate the use of long alkyl chains (C(n)H(2n+1), n ≥ 8) and the imidazolium nitrogen, both of which are part of the ionic liquid chemical structure, as internal references for charge correction. Accurate and reproducible binding energies are obtained which allow comparisons to be made across ionic liquid-based systems.

  15. Blind extraction of exoplanetary spectra

    NASA Astrophysics Data System (ADS)

    Morello, Giuseppe; Waldmann, Ingo; Damiano, Mario; Tinetti, Giovanna

    2016-10-01

    In the last decade, remote sensing spectroscopy enabled characterization of the atmospheres of extrasolar planets. Transmission and emission spectra of tens of transiting exoplanets have been measured with multiple instruments aboard Spitzer and Hubble Space Telescopes as well as ground-based facilities, revealing the presence of chemical species in their atmospheres, and constraining their temperature and pressure profiles.Early analyses were somehow heuristic, leading to some controversies in the literature.A photometric precision of 0.01% is necessary to detect the atmospheric spectral modulations. Current observatories, except Kepler, were not designed to achieve this precision. Data reduction is necessary to minimize the effect of instrument systematics in order to achieve the target precision. In the past, parametric models have extensively been used by most teams to remove correlated noise with the aid of auxiliary information of the instrument, the so-called optical state vectors (OSVs). Such OSVs can include inter- and intra-pixel position of the star or its spectrum, instrument temperatures and inclinations, and/or other parameters. In some cases, different parameterizations led to discrepant results.We recommend the use of blind non-parametric data detrending techniques to overcome those issues. In particular, we adopt Independent Component Analysis (ICA), i.e. a powerful blind source separation (BSS) technique to disentangle the multiple instrument systematics and astrophysical signals in transit/eclipse light curves. ICA does not require a model for the systematics, thence it can be applied to any instrument with little changes, if any. ICA-based algorithms have been applied to Spitzer/IRAC and synthetic observations in photometry (Morello et al. 2014, 2015, 2016; Morello 2015) and to Hubble/WFC3, Hubble/NICMOS and Spitzer/IRS and Hubble/WFC3 in spectroscopy (Damiano, Morello et al., in prep., Waldmann 2012, 2014, Waldmann et al. 2013) with excellent

  16. a Novel Method to Measure Spectra of Cold Molecular Ions

    NASA Astrophysics Data System (ADS)

    Chakrabarty, Satrajit; Holz, Mathias; Campbell, Ewen; Banerjee, Agniva; Gerlich, Dieter; Maier, John P.

    2014-06-01

    A universal method has been developed in our group for measuring the spectra of molecular ions in a 22-pole radio frequency trap at low temperatures. It is based on laser induced inhibition of complex growth (LIICG)1. At low temperatures and high number densities of buffer gas, helium attaches to ions via ternary association. The formation of these weakly bound complexes, however, is inhibited following resonant absorption of the bare molecular ion. The first successful measurements have been demonstrated on the A 2Π_u ← X ^2Σ_g^+ electronic transition of N_2^+, with some thousand N_2^+ ions, helium densities of 1015 cm-3, and storage times of 1 s. The reduction in the number of N_2+-He complexes is the result of an interplay between excitation, radiative and collisional cooling, ternary association, and collision induced dissociation, and is explained using a kinetic model. The method is also applicable to larger molecular species. In this case internal conversion following electronic excitation produces internally "hot" ions, reducing the attachment of helium. The technique is universal because complex formation can be impeded over a wide wavelength range. [1] S. Chakrbarty, M. Holz, E. K. Campbell, A. Banerjee, D. Gerlich, and J. P. Maier, J. Phys. Chem. Lett. 2013, 4, 4051.

  17. Outer-core emission spectra of heavy alkali metals

    NASA Astrophysics Data System (ADS)

    Fink, R. L.; First, P. N.; Flynn, C. P.

    1988-09-01

    We report np5(n+1)s2-->np6(n+1)s emission spectra of K (n=3), Rb (n=4), and Cs (n=5), and compare emission-band characteristics through the series Na-Cs using earlier data for Na. The normalized band profiles of the different alkali metals are remarkably similar when scaled by the Fermi energy EF. However, the spin-orbit partner intensity ratios are far from the ideal value 2, reaching approximately 60 for Rb and above 65 for Cs, mainly owing to Coster-Kronig decays from higher levels. We confirm that the Mahan-Nozières-De Dominicis ``anomaly'' at EF is generally weaker in emission than in absorption. It decreases through the series to become undetectable for emission from Cs. A systematic increase of the core-hole-lifetime width occurs through the column of alkali metals from a reported estimate of 10 meV for Na to a value of 50 meV for Cs. A study of the Fermi-edge shape between 20 and 300 K reveals temperature-dependent phonon broadening in generally good agreement with theoretical predictions. Incomplete relaxation plays only a minor role in the edge processes of the heavy alkali metals. Additional Fermi-edge broadening and the shifted emission edges of surface atoms are observed for alkali-metal films 10-100 Å thick.

  18. Mid-Infrared Spectra of Mercury

    NASA Technical Reports Server (NTRS)

    Cooper, B.; Potter, A. E.; Killen, R. M.; Morgan, T. H.

    2001-01-01

    Mid-infrared (8-13 microns) spectra of radiation emitted from the surface of solar system objects can be interpreted in terms of surface composition. However, the spectral features are weak, and require exceptionally high signal-to-noise ratio spectra to detect them. Ground-based observations of spectra in this region are plagued by strong atmospheric absorptions from water and ozone. High-altitude balloon measurements that avoid atmospheric absorptions can be affected by contamination of the optics by dust. We have developed a technique to obtain mid-infrared spectra of Mercury that minimizes these problems. The resulting spectra show evidence of transparency features that can be used to qualitatively characterize the surface composition. Additional information is contained in the original extended abstract.

  19. Isotope shifts in spectra of molecular liquids

    NASA Astrophysics Data System (ADS)

    Dubrovskaya, E. V.; Kolomiitsova, T. D.; Shurukhina, A. V.; Shchepkin, D. N.

    2016-02-01

    In the IR absorption spectra of low-temperature molecular liquids, we have observed anomalously large isotope shifts of frequencies of vibrational bands that are strong in the dipole absorption. The same effect has also been observed in their Raman spectra. At the same time, in the spectra of cryosolutions, the isotope shifts of the same bands coincide with a high accuracy (±(0.1-0.5) cm-1) with the shifts that are observed in the spectra of the gas phase. The difference between the spectra of examined low-temperature systems is caused by the occurrence of resonant dipole-dipole interactions between spectrally active identical molecules. The calculation of the band contour in the spectrum of liquid freon that we have performed in this work taking into account the resonant interaction between states of simultaneous transitions in isotopically substituted molecules can explain this effect.

  20. PCA: Principal Component Analysis for spectra modeling

    NASA Astrophysics Data System (ADS)

    Hurley, Peter D.; Oliver, Seb; Farrah, Duncan; Wang, Lingyu; Efstathiou, Andreas

    2012-07-01

    The mid-infrared spectra of ultraluminous infrared galaxies (ULIRGs) contain a variety of spectral features that can be used as diagnostics to characterize the spectra. However, such diagnostics are biased by our prior prejudices on the origin of the features. Moreover, by using only part of the spectrum they do not utilize the full information content of the spectra. Blind statistical techniques such as principal component analysis (PCA) consider the whole spectrum, find correlated features and separate them out into distinct components. This code, written in IDL, classifies principal components of IRS spectra to define a new classification scheme using 5D Gaussian mixtures modelling. The five PCs and average spectra for the four classifications to classify objects are made available with the code.

  1. Broadband turbulent spectra in gamma-ray burst light curves

    SciTech Connect

    Van Putten, Maurice H. P. M.; Guidorzi, Cristiano; Frontera, Filippo

    2014-05-10

    Broadband power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long gamma-ray bursts (GRBs). We describe a chirp search method alongside Fourier analysis for signal detection in the Poisson noise-dominated, 2 kHz sampled, BeppoSAX light curves. An efficient numerical implementation is described in O(Nnlog n) operations, where N is the number of chirp templates and n is the length of the light-curve time series, suited for embarrassingly parallel processing. For the detection of individual chirps over a 1 s duration, the method is one order of magnitude more sensitive in signal-to-noise ratio than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope with up to 1 kHz of turbulence identified in low-frequency Fourier analysis. The same continuation is observed in an average spectrum of 42 bright, long GRBs. An outlook on a similar analysis of upcoming gravitational wave data is included.

  2. Transient absorption spectra of the laser-dressed hydrogen atom

    NASA Astrophysics Data System (ADS)

    Murakami, Mitsuko; Chu, Shih-I.

    2013-10-01

    We present a theoretical study of transient absorption spectra of laser-dressed hydrogen atoms, based on numerical solutions of the time-dependent Schrödinger equation. The timing of absorption is controlled by the delay between an extreme ultra violet (XUV) pulse and an infrared (IR) laser field. The XUV pulse is isolated and several hundred attoseconds in duration, which acts as a pump to drive the ground-state electron to excited p states. The subsequent interaction with the IR field produces dressed states, which manifest as sidebands between the 1s-np absorption spectra separated by one IR-photon energy. We demonstrate that the population of dressed states is maximized when the timing of the XUV pulse coincides with the zero crossing of the IR field, and that their energies can be manipulated in a subcycle time scale by adding a chirp to the IR field. An alternative perspective to the problem is to think of the XUV pulse as a probe to detect the dynamical ac Stark shifts. Our results indicate that the accidental degeneracy of the hydrogen excited states is removed while they are dressed by the IR field, leading to large ac Stark shifts. Furthermore, we observe the Autler-Townes doublets for the n=2 and 3 levels using the 656 nm dressing field, but their separation does not agree with the prediction by the conventional three-level model that neglects the dynamical ac Stark shifts.

  3. Test of Lepton Universality in Upsilon(1S) Decays at BaBar

    SciTech Connect

    del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, David Nathan; Hooberman, B.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Osipenkov, I.L.; Tanabe, T.; /more authors..

    2010-06-07

    The ratio R{sub {tau}{mu}}({Upsilon}(1S))={Lambda}{sub {Upsilon}(1S){yields}{tau}{sup +}{tau}{sup -}}/{Lambda}{sub {Upsilon}(1S){yields}{mu}{sup +}{mu}{sup -}} is measured using a sample of (121.8 {+-} 1.2) x 10{sup 6}{Upsilon}(3S) events recorded by the BABAR detector. This measurement is intended as a test of lepton universality and as a search for a possible light pseudoscalar Higgs boson. In the standard model (SM) this ratio is expected to be close to 1. Any significant deviations would violate lepton universality and could be introduced by the coupling to a light pseudoscalar Higgs boson. The analysis studies the decays {Upsilon}(3S) {yields} {Upsilon}(1S){sub {pi}{sup +}{pi}{sup -}}, {Upsilon}(1S) {yields} {ell}{sup +}{ell}{sup -}, where l = {mu}, {tau}. The result, R{sub {tau}{mu}}({Upsilon}(1S))=1.005 {+-} 0.013(stat) {+-} 0.022(syst), shows no deviation from the expected SM value, while improving the precision with respect to previous measurements.

  4. Radiative decays of the {upsilon}(1S) to a pair of charged hadrons

    SciTech Connect

    Athar, S.B.; Avery, P.; Breva-Newell, L.; Patel, R.; Potlia, V.; Stoeck, H.; Yelton, J.; Rubin, P.; Cawlfield, C.; Eisenstein, B.I.; Gollin, G.D.; Karliner, I.; Kim, D.; Lowrey, N.; Naik, P.; Sedlack, C.; Selen, M.; White, E.J.; Williams, J.; Wiss, J.

    2006-02-01

    Using data obtained with the CLEO III detector, running at the Cornell Electron Storage Ring (CESR), we report on a new study of exclusive radiative {upsilon}(1S) decays into the final states {gamma}{pi}{sup +}{pi}{sup -}, {gamma}K{sup +}K{sup -}, and {gamma}pp. We present branching ratio measurements for the decay modes {upsilon}(1S){yields}{gamma}f{sub 2}(1270), {upsilon}(1S){yields}{gamma}f{sub 2}{sup '}(1525), and {upsilon}(1S){yields}{gamma}K{sup +}K{sup -}; helicity production ratios for f{sub 2}(1270) and f{sub 2}{sup '}(1525); upper limits for the decay {upsilon}(1S){yields}{gamma}f{sub J}(2200), with f{sub J}(2220){yields}{pi}{sup +}{pi}{sup -}, K{sup +}K{sup -}, pp; and an upper limit for the decay {upsilon}(1S){yields}{gamma}X(1860), with X(1860){yields}{gamma}pp.

  5. Test of lepton universality in Υ(1S) decays at BABAR.

    PubMed

    del Amo Sanchez, P; Lees, J P; Poireau, V; Prencipe, E; Tisserand, V; Garra Tico, J; Grauges, E; Martinelli, M; Palano, A; Pappagallo, M; Eigen, G; Stugu, B; Sun, L; Battaglia, M; Brown, D N; Hooberman, B; Kerth, L T; Kolomensky, Yu G; Lynch, G; Osipenkov, I L; Tanabe, T; Hawkes, C M; Soni, N; Watson, A T; Koch, H; Schroeder, T; Asgeirsson, D J; Hearty, C; Mattison, T S; McKenna, J A; Khan, A; Randle-Conde, A; Blinov, V E; Buzykaev, A R; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, K Yu; Yushkov, A N; Bondioli, M; Curry, S; Kirkby, D; Lankford, A J; Mandelkern, M; Martin, E C; Stoker, D P; Atmacan, H; Gary, J W; Liu, F; Long, O; Vitug, G M; Yasin, Z; Sharma, V; Campagnari, C; Hong, T M; Kovalskyi, D; Richman, J D; Eisner, A M; Heusch, C A; Kroseberg, J; Lockman, W S; Martinez, A J; Schalk, T; Schumm, B A; Seiden, A; Winstrom, L O; Cheng, C H; Doll, D A; Echenard, B; Hitlin, D G; Ongmongkolkul, P; Porter, F C; Rakitin, A Y; Andreassen, R; Dubrovin, M S; Mancinelli, G; Meadows, B T; Sokoloff, M D; Bloom, P C; Ford, W T; Gaz, A; Hirschauer, J F; Nagel, M; Nauenberg, U; Smith, J G; Wagner, S R; Ayad, R; Toki, W H; Hauke, A; Jasper, H; Karbach, T M; Merkel, J; Petzold, A; Spaan, B; Wacker, K; Kobel, M J; Schubert, K R; Schwierz, R; Bernard, D; Verderi, M; Clark, P J; Playfer, S; Watson, J E; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cecchi, A; Cibinetto, G; Fioravanti, E; Franchini, P; Luppi, E; Munerato, M; Negrini, M; Petrella, A; Piemontese, L; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Nicolaci, M; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Contri, R; Guido, E; Lo Vetere, M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Tosi, S; Bhuyan, B; Morii, M; Adametz, A; Marks, J; Schenk, S; Uwer, U; Bernlochner, F U; Lacker, H M; Lueck, T; Volk, A; Dauncey, P D; Tibbetts, M; Behera, P K; Mallik, U; Chen, C; Cochran, J; Crawley, H B; Dong, L; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gao, Y Y; Gritsan, A V; Guo, Z J; Arnaud, N; Davier, M; Derkach, D; Firmino da Costa, J; Grosdidier, G; Le Diberder, F; Lutz, A M; Malaescu, B; Perez, A; Roudeau, P; Schune, M H; Serrano, J; Sordini, V; Stocchi, A; Wang, L; Wormser, G; Lange, D J; Wright, D M; Bingham, I; Burke, J P; Chavez, C A; Coleman, J P; Fry, J R; Gabathuler, E; Gamet, R; Hutchcroft, D E; Payne, D J; Touramanis, C; Bevan, A J; Di Lodovico, F; Sacco, R; Sigamani, M; Cowan, G; Paramesvaran, S; Wren, A C; Brown, D N; Davis, C L; Denig, A G; Fritsch, M; Gradl, W; Hafner, A; Alwyn, K E; Bailey, D; Barlow, R J; Jackson, G; Lafferty, G D; West, T J; Anderson, J; Cenci, R; Jawahery, A; Roberts, D A; Simi, G; Tuggle, J M; Dallapiccola, C; Salvati, E; Cowan, R; Dujmic, D; Fisher, P H; Sciolla, G; Yamamoto, R K; Zhao, M; Patel, P M; Robertson, S H; Schram, M; Biassoni, P; Lazzaro, A; Lombardo, V; Palombo, F; Stracka, S; Cremaldi, L; Godang, R; Kroeger, R; Sonnek, P; Summers, D J; Zhao, H W; Nguyen, X; Simard, M; Taras, P; De Nardo, G; Monorchio, D; Onorato, G; Sciacca, C; Raven, G; Snoek, H L; Jessop, C P; Knoepfel, K J; LoSecco, J M; Wang, W F; Corwin, L A; Honscheid, K; Kass, R; Morris, J P; Rahimi, A M; Blount, N L; Brau, J; Frey, R; Igonkina, O; Kolb, J A; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Castelli, G; Feltresi, E; Gagliardi, N; Margoni, M; Morandin, M; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Ben-Haim, E; Bonneaud, G R; Briand, H; Chauveau, J; Hamon, O; Leruste, Ph; Marchiori, G; Ocariz, J; Prendki, J; Sitt, S; Biasini, M; Manoni, E; Angelini, C; Batignani, G; Bettarini, S; Calderini, G; Carpinelli, M; Cervelli, A; Forti, F; Giorgi, M A; Lusiani, A; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Lopes Pegna, D; Lu, C; Olsen, J; Smith, A J S; Telnov, A V; Anulli, F; Baracchini, E; Cavoto, G; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Li Gioi, L; Mazzoni, M A; Piredda, G; Renga, F; Ebert, M; Hartmann, T; Leddig, T; Schröder, H; Waldi, R; Adye, T; Franek, B; Olaiya, E O; Wilson, F F; Emery, S; Hamel de Monchenault, G; Vasseur, G; Yèche, Ch; Zito, M; Allen, M T; Aston, D; Bard, D J; Bartoldus, R; Benitez, J F; Cartaro, C; Convery, M R; Dorfan, J; Dubois-Felsmann, G P; Dunwoodie, W; Field, R C; Franco Sevilla, M; Fulsom, B G; Gabareen, A M; Graham, M T; Grenier, P; Hast, C; Innes, W R; Kelsey, M H; Kim, H; Kim, P; Kocian, M L; Leith, D W G S; Li, S; Lindquist, B; Luitz, S; Luth, V; Lynch, H L; MacFarlane, D B; Marsiske, H; Muller, D R; Neal, H; Nelson, S; O'Grady, C P; Ofte, I; Perl, M; Ratcliff, B N; Roodman, A; Salnikov, A A; Santoro, V; Schindler, R H; Schwiening, J; Snyder, A; Su, D; Sullivan, M K; Suzuki, K; Thompson, J M; Va'vra, J; Wagner, A P; Weaver, M; West, C A; Wisniewski, W J; Wittgen, M; Wright, D H; Wulsin, H W; Yarritu, A K; Young, C C; Ziegler, V; Chen, X R; Park, W; Purohit, M V; White, R M; Wilson, J R; Sekula, S J; Bellis, M; Burchat, P R; Edwards, A J; Miyashita, T S; Ahmed, S; Alam, M S; Ernst, J A; Pan, B; Saeed, M A; Zain, S B; Guttman, N; Soffer, A; Lund, P; Spanier, S M; Eckmann, R; Ritchie, J L; Ruland, A M; Schilling, C J; Schwitters, R F; Wray, B C; Izen, J M; Lou, X C; Bianchi, F; Gamba, D; Pelliccioni, M; Bomben, M; Della Ricca, G; Lanceri, L; Vitale, L; Azzolini, V; Lopez-March, N; Martinez-Vidal, F; Milanes, D A; Oyanguren, A; Albert, J; Banerjee, Sw; Choi, H H F; Hamano, K; King, G J; Kowalewski, R; Lewczuk, M J; Nugent, I M; Roney, J M; Sobie, R J; Gershon, T J; Harrison, P F; Ilic, J; Latham, T E; Mohanty, G B; Puccio, E M T; Band, H R; Chen, X; Dasu, S; Flood, K T; Pan, Y; Pierini, M; Prepost, R; Vuosalo, C O; Wu, S L

    2010-05-14

    The ratio R(τμ)(Υ(1S))=Γ(Υ(1S)→τ+ τ-)/Γ(Υ(1S)→μ+ μ-) is measured using a sample of (121.8±1.2)×10(6)Υ(3S) events recorded by the BABAR detector. This measurement is intended as a test of lepton universality and as a search for a possible light pseudoscalar Higgs boson. In the standard model (SM) this ratio is expected to be close to 1. Any significant deviations would violate lepton universality and could be introduced by the coupling to a light pseudoscalar Higgs boson. The analysis studies the decays Υ(3S)→Υ(1S)π+ π-, Υ(1S)→l+ l-, where l=μ, τ. The result, R(τμ)(Υ(1S))=1.005±0.013(stat)±0.022(syst), shows no deviation from the expected SM value, while improving the precision with respect to previous measurements.

  6. MAP1S Protein Regulates the Phagocytosis of Bacteria and Toll-like Receptor (TLR) Signaling.

    PubMed

    Shi, Ming; Zhang, Yifan; Liu, Leyuan; Zhang, Tingting; Han, Fang; Cleveland, Joseph; Wang, Fen; McKeehan, Wallace L; Li, Yu; Zhang, Dekai

    2016-01-15

    Phagocytosis is a critical cellular process for innate immune defense against microbial infection. The regulation of phagocytosis process is complex and has not been well defined. An intracellular molecule might regulate cell surface-initiated phagocytosis, but the underlying molecular mechanism is poorly understood (1). In this study, we found that microtubule-associated protein 1S (MAP1S), a protein identified recently that is involved in autophagy (2), is expressed primarily in macrophages. MAP1S-deficient macrophages are impaired in the phagocytosis of bacteria. Furthermore, we demonstrate that MAP1S interacts directly with MyD88, a key adaptor of Toll-like receptors (TLRs), upon TLR activation and affects the TLR signaling pathway. Intriguingly, we also observe that, upon TLR activation, MyD88 participates in autophagy processing in a MAP1S-dependent manner by co-localizing with MAP1 light chain 3 (MAP1-LC3 or LC3). Therefore, we reveal that an intracellular autophagy-related molecule of MAP1S controls bacterial phagocytosis through TLR signaling.

  7. Adsorption geometry and core excitation spectra of three phenylpropene isomers on Cu(111)

    SciTech Connect

    Kolczewski, C.; Williams, F. J.; Cropley, R. L.; Vaughan, O. P. H.; Urquhart, A. J.; Tikhov, M. S.; Lambert, R. M.; Hermann, K.

    2006-07-21

    Theoretical C 1s near edge x-ray absorption fine structure (NEXAFS) spectra for the C{sub 9}H{sub 10} isomers trans-methylstyrene, {alpha}-methylstyrene, and allylbenzene in gas phase and adsorbed at Cu(111) surfaces have been obtained from density functional theory calculations where adsorbate geometries were determined by corresponding total energy optimizations. The three species show characteristic differences in widths and peak shapes of the lowest C 1s{yields}{pi}* transitions which are explained by different coupling of the {pi}-electron system of the C{sub 6} ring with that of the side chain in the molecules as well as by the existence of nonequivalent carbon centers. The adsorbed molecules bind only weakly with the substrate which makes the use of theoretical NEXAFS spectra of the oriented free molecules meaningful for an interpretation of experimental angle-resolved NEXAFS spectra of the adsorbate systems obtained in this work. However, a detailed quantitative account of relative peak intensities requires theoretical angle-resolved NEXAFS spectra of the complete adsorbate systems which have been evaluated within the surface cluster approach. The comparison with experiment yields almost perfect agreement and confirms the reliability of the calculated equilibrium geometries of the adsorbates. This can help to explain observed differences in the catalytic epoxidation of the three molecules on Cu(111) based on purely geometric considerations.

  8. Atomic physics modeling of transmission spectra of Sc-doped aerogel foams to support OMEGA experiments

    NASA Astrophysics Data System (ADS)

    Johns, H. M.; Lanier, N. E.; Kline, J. L.; Fontes, C. J.; Perry, T. S.; Fryer, C. L.; Brown, C. R. D.; Morton, J. W.; Hager, J. D.; Sherrill, M. E.

    2016-11-01

    We present synthetic transmission spectra generated with PrismSPECT utilizing both the ATBASE model and the Los Alamos opacity library (OPLIB) to evaluate whether an alternative choice in atomic data will impact modeling of experimental data from radiation transport experiments using Sc-doped aerogel foams (ScSi6O12 at 75 mg/cm3 density). We have determined that in the 50-200 eV Te range there is a significant difference in the 1s-3p spectra, especially below 100 eV, and for Te = 200 eV above 5000 eV in photon energy. Examining synthetic spectra generated using OPLIB with 300 resolving power reveals spectral sensitivity to Te changes of ˜3 eV.

  9. Efficient eco-friendly inverted quantum dot sensitized solar cells† †Electronic supplementary information (ESI) available: TEM images of QDs, XPS spectra, UV-vis and PL spectra of the sensitized electrodes, details about photophysical characterization and IPCE spectra interpretation. See DOI: 10.1039/c5ta06769c Click here for additional data file.

    PubMed Central

    Park, Jinhyung; Sajjad, Muhammad T.; Jouneau, Pierre-Henri; Ruseckas, Arvydas; Faure-Vincent, Jérôme; Reiss, Peter

    2016-01-01

    Recent progress in quantum dot (QD) sensitized solar cells has demonstrated the possibility of low-cost and efficient photovoltaics. However, the standard device structure based on n-type materials often suffers from slow hole injection rate, which may lead to unbalanced charge transport. We have fabricated efficient p-type (inverted) QD sensitized cells, which combine the advantages of conventional QD cells with p-type dye sensitized configurations. Moreover, p-type QD sensitized cells can be used in highly promising tandem configurations with n-type ones. QDs without toxic Cd and Pb elements and with improved absorption and stability were successfully deposited onto mesoporous NiO electrode showing good coverage and penetration according to morphological analysis. Detailed photophysical charge transfer studies showed that high hole injection rates (108 s–1) observed in such systems are comparable with electron injection in conventional n-type QD assemblies. Inverted solar cells fabricated with various QDs demonstrate excellent power conversion efficiencies of up to 1.25%, which is 4 times higher than the best values for previous inverted QD sensitized cells. Attempts to passivate the surface of the QDs show that traditional methods of reduction of recombination in the QD sensitized cells are not applicable to the inverted architectures. PMID:27478616

  10. Quantification of the toxic hexavalent chromium content in an organic matrix by X-ray photoelectron spectroscopy (XPS) and ultra-low-angle microtomy (ULAM)

    NASA Astrophysics Data System (ADS)

    Greunz, Theresia; Duchaczek, Hubert; Sagl, Raffaela; Duchoslav, Jiri; Steinberger, Roland; Strauß, Bernhard; Stifter, David

    2017-02-01

    Cr(VI) is known for its corrosion inhibitive properties and is, despite legal regulations, still a potential candidate to be added to thin (1-3 μm) protective coatings applied on, e.g., electrical steel as used for transformers, etc. However, Cr(VI) is harmful to the environment and to the human health. Hence, a reliable quantification of it is of decisive interest. Commonly, an alkaline extraction with a photometric endpoint detection of Cr(VI) is used for such material systems. However, this procedure requires an accurate knowledge on sample parameters such as dry film thickness and coating density that are occasionally associated with significant experimental errors. We present a comprehensive study of a coating system with a defined Cr(VI) pigment concentration applied on electrical steel. X-ray photoelectron spectroscopy (XPS) was employed to resolve the elemental chromium concentration and the chemical state. Turning to the fact that XPS is extremely surface sensitive (<10 nm) and that the lowest commonly achievable lateral resolution is a number of times higher than the coating thickness (∼2 μm), a bulk analysis was achieved with XPS line scans on extended wedge-shaped tapers through the coating. For that purpose a special sample preparation step performed on an ultra-microtome was required prior to analysis. Since a temperature increase leads to a reduction of Cr(VI) we extend our method on samples, which were subjected to different curing temperatures. We show that our proposed approach now allows to determine the elemental and Cr(VI) concentration and distribution inside the coating.

  11. EIS and XPS investigations on the corrosion mechanism of ternary Zn-Co-Mo alloy coatings in NaCl solution

    NASA Astrophysics Data System (ADS)

    Winiarski, J.; Tylus, W.; Szczygieł, B.

    2016-02-01

    The changes in composition of the corrosion products of electrodeposited ternary Zn-Co-Mo alloy coatings on AISI 1015 steel during exposure to 0.5 mol dm-3 NaCl solution were investigated. XPS studies demonstrated that at the initial stage of corrosion on the surface of Zn-Co-Mo coating zinc hydroxide layer is formed. Hydroxyl groups react with chloride and carbonate ions which lead to the formation of zinc hydroxy carbonates and zinc hydroxy chlorides. The share of these compounds in the oxidation products is initially large. However, with time zinc hydroxy compounds slowly changes to zinc oxide, which is more stable corrosion product. It was estimated that after 24 h of exposure to NaCl solution nearly 60% of zinc detected on the surface of Zn-Co-Mo coating was present in the ZnO form, 18% in the form of zinc hydroxy chloride, and more than 21% as zinc hydroxy carbonate. XPS analyses revealed that the amount of zinc hydroxy chloride increases as the exposure time lengthens and it is significantly higher than at the surface of binary Zn-Co coating. The presence of crystalline zinc chloride hydroxide as a stable product of corrosion of ternary Zn-Co-Mo alloy coating in a 0.5 mol dm-3 NaCl solution was confirmed by XRD analysis. According to XRD and FTIR other zinc corrosion products like: ZnO, Zn(OH)2 and Zn5(CO3)2(OH)6 were also present. The results of XPS and EIS measurements allow us to assume that in the presence of Mo in the alloy, on the surface of ternary Zn-Co-Mo alloy (3.4 wt.% Co, 2.7 wt.% Mo) coating more zinc hydroxy chloride is formed, which favors higher corrosion resistance of this coating.

  12. XPS, TDS, and AFM studies of surface chemistry and morphology of Ag-covered L-CVD SnO2 nanolayers.

    PubMed

    Kwoka, Monika; Ottaviano, Luca; Koscielniak, Piotr; Szuber, Jacek

    2014-01-01

    This is well known that the selectivity and sensitivity of tin dioxide (SnO2) thin film sensors for the detection of low concentration of volatile sulfides such as H2S in air can be improved by small amount of Ag additives. In this paper we present the results of comparative X-ray photoelectron spectroscopy (XPS), thermal desorption spectroscopy (TDS), and atomic force microscopy (AFM) studies of the surface chemistry and morphology of SnO2 nanolayers obtained by laser-enhanced chemical vapor deposition (L-CVD) additionally covered with 1 monolayer (ML) of Ag. For as deposited SnO2 nanolayers, a mixture of tin oxide (SnO) and tin dioxide (SnO2) with the [C]/[Sn] ratio of approximately 1.3 was observed. After dry air exposure, the [O]/[Sn] ratio slightly increased to approximately 1.55. Moreover, an evident increasing of C contamination was observed with [C]/[Sn] ratio of approximately 3.5. After TDS experiment, the [O]/[Sn] ratio goes back to 1.3, whereas C contamination evidently decreases (by factor of 3). Simultaneously, the Ag concentration after air exposure and TDS experiment subsequently decreased (finally by factor of approximately 2), which was caused by the diffusion of Ag atoms into the subsurface layers related to the grain-type surface morphology of Ag-covered L-CVD SnO2 nanolayers, as confirmed by XPS ion depth profiling studies. The variation of surface chemistry of the Ag-covered L-CVD SnO2 after air exposure observed by XPS was in a good correlation with the desorption of residual gases from these nanolayers observed in TDS experiments.

  13. Characterization of the cell surface and cell wall chemistry of drinking water bacteria by combining XPS, FTIR spectroscopy, modeling, and potentiometric titrations.

    PubMed

    Ojeda, Jesús J; Romero-Gonzalez, María E; Bachmann, Robert T; Edyvean, Robert G J; Banwart, Steven A

    2008-04-15

    Aquabacterium commune, a predominant member of European drinking water biofilms, was chosen as a model bacterium to study the role of functional groups on the cell surface that control the changes in the chemical cell surface properties in aqueous electrolyte solutions at different pH values. Cell surface properties of A. commune were examined by potentiometric titrations, modeling, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. By combining FTIR data at different pH values and potentiometric titration data with thermodynamic model optimization, the presence, concentration, and changes of organic functional groups on the cell surface (e.g., carboxyl, phosphoryl, and amine groups) were inferred. The pH of zero proton charge, pH(zpc) = 3.7, found from titrations of A. commune at different electrolyte concentrations and resulting from equilibrium speciation calculations suggests that the net surface charge is negative at drinking water pH in the absence of other charge determining ions. In situ FTIR was used to describe and monitor chemical interactions between bacteria and liquid solutions at different pH in real time. XPS analysis was performed to quantify the elemental surface composition, to assess the local chemical environment of carbon and oxygen at the cell wall, and to calculate the overall concentrations of polysaccharides, peptides, and hydrocarbon compounds of the cell surface. Thermodynamic parameters for proton adsorption are compared with parameters for other gram-negative bacteria. This work shows how the combination of potentiometric titrations, modeling, XPS, and FTIR spectroscopy allows a more comprehensive characterization of bacterial cell surfaces and cell wall reactivity as the initial step to understand the fundamental mechanisms involved in bacterial adhesion to solid surfaces and transport in aqueous systems.

  14. XPS, TDS, and AFM studies of surface chemistry and morphology of Ag-covered L-CVD SnO2 nanolayers

    PubMed Central

    2014-01-01

    This is well known that the selectivity and sensitivity of tin dioxide (SnO2) thin film sensors for the detection of low concentration of volatile sulfides such as H2S in air can be improved by small amount of Ag additives. In this paper we present the results of comparative X-ray photoelectron spectroscopy (XPS), thermal desorption spectroscopy (TDS), and atomic force microscopy (AFM) studies of the surface chemistry and morphology of SnO2 nanolayers obtained by laser-enhanced chemical vapor deposition (L-CVD) additionally covered with 1 monolayer (ML) of Ag. For as deposited SnO2 nanolayers, a mixture of tin oxide (SnO) and tin dioxide (SnO2) with the [C]/[Sn] ratio of approximately 1.3 was observed. After dry air exposure, the [O]/[Sn] ratio slightly increased to approximately 1.55. Moreover, an evident increasing of C contamination was observed with [C]/[Sn] ratio of approximately 3.5. After TDS experiment, the [O]/[Sn] ratio goes back to 1.3, whereas C contamination evidently decreases (by factor of 3). Simultaneously, the Ag concentration after air exposure and TDS experiment subsequently decreased (finally by factor of approximately 2), which was caused by the diffusion of Ag atoms into the subsurface layers related to the grain-type surface morphology of Ag-covered L-CVD SnO2 nanolayers, as confirmed by XPS ion depth profiling studies. The variation of surface chemistry of the Ag-covered L-CVD SnO2 after air exposure observed by XPS was in a good correlation with the desorption of residual gases from these nanolayers observed in TDS experiments. PMID:24936162

  15. IR, FT-ICR-MS studies on (1'S, 6'S)-1-cyclopropyl-7-(2,8-diazabicyclo[4.3.0] non-8-yl)-6-fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid hydrochloride salt.

    PubMed

    Lin, Zhiwei

    2014-01-01

    The infrared spectra of (1'S, 6'S)-1-cyclopropyl-7-(2,8-diazabicyclo[4.3.0] non-8-yl)-6-fluoro-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid hydrochloride salt (CLF-HCl) were studied and compared with free base. Their fragmentation pathways were investigated using tandem mass spectrometric (MS/MS) techniques on Fourier-transform ion cyclotron resonance spectrum, and many characteristic fragment ions were found.

  16. Computer processing of tunable diode laser spectra

    NASA Technical Reports Server (NTRS)

    May, Randy D.

    1989-01-01

    A computer-controlled tunable diode laser spectrometer and spectral analysis software are described. The three-channel system records simultaneously the transmission of a subject gas, a temperature-stabilized etalon, and a calibration gas. The software routines are applied to diode laser spectra of HNO3 and NO2 to illustrate the procedures adopted for conversion of raw spectral data to useful transmission and harmonic spectra. Extraction of line positions, absorption intensities, collisional broadening coefficients, and gas concentrations from recorded spectra is also described.

  17. Analysis of atmospheric spectra for trace gases

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.; Seals, Robert K., Jr.; Smith, Mary Ann H.; Goldman, Aaron; Murcray, David G.; Murcray, Frank J.

    1990-01-01

    The objective is the comprehensive analysis of high resolution atmospheric spectra recorded in the middle-infrared region to obtain simultaneous measurements of coupled parameters (gas concentrations of key trace constituents, total column amounts, pressure, and temperature) in the stratosphere and upper troposphere. Solar absorption spectra recorded at 0.002 and 0.02 cm exp -1 resolutions with the University of Denver group's balloon-borne, aircraft borne, and ground-based interferometers and 0.005 to 0.01 cm exp -1 resolution solar spectra from Kitt Peak are used in the analyses.

  18. Vibrational spectra and structure of isopropylbenzene

    NASA Astrophysics Data System (ADS)

    Fishman, A. I.; Noskov, A. I.; Remizov, A. B.; Chachkov, D. V.

    2008-12-01

    Infrared spectra (4000-400 cm -1) and Raman spectra (1700-40 cm -1) of the liquid and two crystalline solids of isopropylbenzene (cumene) and isopropylbenzene-d 12 have been recorded. The spectra indicate that in the liquid and crystalline solids isopropylbenzene exists in planar conformation only (C sbnd H bond is in the plane of the benzene ring). An assignment of the observed band wave numbers both isopropylbenzene and isopropylbenzene-d 12 is discussed by comparison with normal mode wave numbers and IR intensities calculated from ab initio 6-31G (d) force fields.

  19. The relevance of paternity analysis in Romanian population using the D1S80 locus.

    PubMed

    Ceacăreanu, A C; Ceacăreanu, B

    1999-01-01

    At present, DNA fingerprinting for human identification and paternity testing is a necessary and usual procedure. D1S80 is one of the best known polymorphic loci showing a VNTR, and exhibiting a high heterozygosity. This genetic locus, with a Tsp 509 I polymorphism of its 5' flanking sequence (1, 9), have been successfully amplified from human genomic DNA isolated from blood. The Tsp 509 I polymorphism was detected by restriction after PCR amplification. We tested the relevance of paternity analysis using the D1S80 locus considering the allele frequency distribution characteristic for our country. Paternal and maternal bands were compared with the children's DNA patterns. Our data include a comparison between D1S80 alleles amplified from mother, child and the supposed father for three tested families. This study was the first of this type made in Romania. We concluded a good power of discrimination and exclusion for this locus. It can be used successfully in the case of subtypes with low frequencies, and this is frequent for our population because of the high heterozygosity of D1S80 subtypes in Romanian population. We recommend the D1S80 use for exclusion paternity tests in Romanian population, as a very useful molecular tool, but we also recommend a complete set of molecular markers for confirmation paternity test in the same population.

  20. G1/S control of anchorage-independent growth in the fibroblast cell cycle

    PubMed Central

    1991-01-01

    We have developed methodology to identify the block to anchorage- independent growth and position it within the fibroblast cell cycle. Results with NRK fibroblasts show that mitogen stimulation of the G0/G1 transition and G1-associated increases in cell size are minimally affected by loss of cell anchorage. In contrast, the induction of G1/S cell cycle genes and DNA synthesis is markedly inhibited when anchorage is blocked. Moreover, we demonstrate that the anchorage-dependent transition maps to late G1 and shortly before activation of the G1/S p34cdc2-like kinase. The G1/S block was also detectable in NIH-3T3 cells. Our results: (a) distinguish control of cell cycle progression by growth factors and anchorage; (b) indicate that anchorage mediates G1/S control in fibroblasts; and (c) identify a physiologic circumstance in which the phenotype of mammalian cell cycle arrest would closely resemble Saccharomyces cerevisiae START. The close correlation between anchorage independence in vitro and tumorigenicity in vivo emphasizes the key regulatory role for G1/S control in mammalian cells. PMID:1955482

  1. The Xbp1s/GalE axis links ER stress to postprandial hepatic metabolism.

    PubMed

    Deng, Yingfeng; Wang, Zhao V; Tao, Caroline; Gao, Ningguo; Holland, William L; Ferdous, Anwarul; Repa, Joyce J; Liang, Guosheng; Ye, Jin; Lehrman, Mark A; Hill, Joseph A; Horton, Jay D; Scherer, Philipp E

    2013-01-01

    Postprandially, the liver experiences an extensive metabolic reprogramming that is required for the switch from glucose production to glucose assimilation. Upon refeeding, the unfolded protein response (UPR) is rapidly, though only transiently, activated. Activation of the UPR results in a cessation of protein translation, increased chaperone expression, and increased ER-mediated protein degradation, but it is not clear how the UPR is involved in the postprandial switch to alternate fuel sources. Activation of the inositol-requiring enzyme 1 (IRE1) branch of the UPR signaling pathway triggers expression of the transcription factor Xbp1s. Using a mouse model with liver-specific inducible Xbp1s expression, we demonstrate that Xbp1s is sufficient to provoke a metabolic switch characteristic of the postprandial state, even in the absence of caloric influx. Mechanistically, we identified UDP-galactose-4-epimerase (GalE) as a direct transcriptional target of Xbp1s and as the key mediator of this effect. Our results provide evidence that the Xbp1s/GalE pathway functions as a novel regulatory nexus connecting the UPR to the characteristic postprandial metabolic changes in hepatocytes.

  2. BECN1s, a short splice variant of BECN1, functions in mitophagy.

    PubMed

    Cheng, Bing; Xu, An; Qiao, Mengran; Wu, Qiao; Wang, Wenyu; Mei, Yide; Wu, Mian

    2015-11-02

    Mitochondria selective autophagy, known as mitophagy, plays a pivotal role in several biological processes, such as elimination of the damaged mitochondria, removal of the mitochondria from immature red blood cells and sperm. The defects in mitophagy are associated with a wide spectrum of human diseases, including neurodegenerative disease, aging, cardiac disease and autoimmune disease. However, the mechanism underlying mitophagy remains largely unclear. Here, we report the characterization of a novel splice variant of BECN1/Beclin 1, BECN1s, which is produced by an alternative splicing mechanism. BECN1s is primarily associated with the outer-membrane of mitochondria. Unlike unspliced BECN1, which is essential for nonselective macroautophagy induction, BECN1s is indispensible for mitochondria-selective autophagy. Furthermore, BECN1s plays an important role in starvation- and membrane depolarization-induced mitophagy. Taken together, our findings broaden the view of BECN1 as an important regulator in autophagy, and implicate BECN1s as a specific mitophagy mediator.

  3. Interaction of atomic oxygen with thin film and bulk copper: An XPS, AES, XRD, and profilometer study

    NASA Technical Reports Server (NTRS)

    Raikar, Genesh N.; Gregory, John C.; Christl, Ligia C.; Peters, Palmer N.

    1992-01-01

    The University of Alabama in Huntsville (UAH) experiment A-0114 was designed primarily to study degradation of material surfaces due to low earth orbital (LEO) atmospheric oxygen. The experiment contained 128 one inch circular samples: metals, polymers, carbons, and semiconductors. Among metal samples, copper has shown some interesting new results. Two types of copper samples, a film sputter coated on fused silica and a bulk piece of OFHC copper, were characterized employing a variety of techniques such as X-ray and Auger electron spectroscopies, X-ray diffraction, and high resolution profilometry. Cu 2p core level spectra were used to characterize the presence of Cu2O and CuO in addition to Cu Auger LMM lines. These results are supported by our recent X-ray diffraction studies which clearly establish the presence of Cu oxides which we were unable to prove in our earlier work. Profilometry showed an increase in thickness of the film sample where exposed to 106.7 +/- 0.5 nm from an initial thickness of 74.2 +/- 1.1 nm. Further studies with SEM and ellipsometry are underway.

  4. Laser induced Te diffusion in amorphous As50Se50 thin films probed by FTIR and XPS

    NASA Astrophysics Data System (ADS)

    Behera, Mukta; Panda, Rozalin; Naik, Ramakanta

    2017-01-01

    In the present report, we have demonstrated the combine effect of deposition and photo diffusion of Te into As50Se50 chalcogenide thin films. The influence of Te deposition onto As50Se50 layer has modified the optical parameters. The thermally evaporated Te/As50Se50 bilayer film is irradiated with near bandgap laser light. The optical and structural property of Te/As50Se50 bilayer film under the influence of laser irradiation has been investigated by X-ray photo electron spectroscopy and Fourier transform infrared spectroscopy. The As3d, Se3d and Te4d core level peaks of the photo diffused film show significant changes in shape and position in comparisons with those obtained for non irradiated films. The extensive analysis by deconvoluting the spectra shows the Te diffusion into As50Se50 matrix by forming Te-As-Se layer. The optical band gap of the diffused region is found to be decreased with the increase of density of states in the band edge. The change in transmissivity and absorption coefficient modified the optical constants which is discussed in the light of the present result.

  5. Investigation of Raman spectra of polyethylene terephthalate

    NASA Astrophysics Data System (ADS)

    Zhu, Changjun; Tong, Na; Song, Lixin; Zhang, Guoqing

    2015-08-01

    Raman spectrometry was employed to study the characteristics of Raman spectra of polyethylene terephthalate (PET), which were treated with sodium hydroxide, sulfuric acid and copper sulfate, respectively. Raman spectra under different conditions were obtained and the characteristics of the Raman spectra were analyzed. The morphology structures were observed under different conditions using Atomic Force Microscope. The results show that the spectral intensity of PET treated with sodium hydroxide is higher than that untreated between 200-1750 cm-1, while the intensity of PET treated with sodium hydroxide is lower than that untreated beyond 1750 cm-1 and the fluorescence background of Raman spectra is decreased. The spectral intensity of PET treated with sulfuric acid is remarkably reduced than that untreated, and the intensity of PET treated with copper sulphate is much higher than that untreated.

  6. Spectra: Time series power spectrum calculator

    NASA Astrophysics Data System (ADS)

    Gallardo, Tabaré

    2017-01-01

    Spectra calculates the power spectrum of a time series equally spaced or not based on the Spectral Correlation Coefficient (Ferraz-Mello 1981, Astron. Journal 86 (4), 619). It is very efficient for detection of low frequencies.

  7. Spatial evolution of ocean wave spectra

    NASA Technical Reports Server (NTRS)

    Beal, R. C.

    1981-01-01

    The spatially evolving deep water synthetic aperture radar (SAR) directional spectra of a mixed ocean wave system are compared with a comprehensive set of surface and aircraft measurements. The evolution of the SAR spectra, at least for ocean wavelengths greater than 80 m, is seen as generally consistent with the auxiliary data set in both time and space. From the spatial evolution of the angular component of the spectra, it is possible to project back to an apparent remote storm source that is also consistent with the storm location via GOES satellite imagery. The data provide compelling evidence that the spatial evolution of SAR ocean wave spectra can be a useful tool in global ocean wave monitoring and forecasting.

  8. Synthesis and Spectra of Vanadium Complexes.

    ERIC Educational Resources Information Center

    Ophardt, Charles E.; Stupgia, Sean

    1984-01-01

    Describes an experiment which illustrates simple synthetic techniques, redox principles in synthesis reactions, interpretation of visible spectra using Orgel diagrams, and the spectrochemical series. The experiment is suitable for the advanced undergraduate inorganic chemistry laboratory. (JN)

  9. An analysis of middle ultraviolet dayglow spectra

    NASA Astrophysics Data System (ADS)

    Walden, Billie S.

    1991-12-01

    Middle ultraviolet spectra from 1800 to 3400A are analyzed. These spectra were obtained from the March 1990 rocket flight of the NPS MUSTANG instrument over the altitudes 105km to 315km. The data were compared with computer generated synthetic spectra. A least squares fitting procedure was developed for this purpose. Each data point was weighted using the standard deviation of the means. Synthetic spectra were generated for the following emissions: N2 Vegard-Kaphan; N2 Lyman-Birge-Hopfield; NO gamma, delta, and epsilon; OI 2972A, OII 2470A; and NII 2143A. Altitude profiles for the emissions were obtained. Tentative identification was made of the OIII 2853A emission. A comparison of VK and LBH profiles demonstrates the process of N2 A-state quenching by atomic oxygen.

  10. [Spectra of dark green jade from Myanmar].

    PubMed

    Mao, Jian; Chai, Lin-Tao; Guo, Shou-Guo; Fan, Jian-Liang; Bao, Feng

    2013-05-01

    Chemical compositions and spectral characteristics of one type of dark green jades assumed from omphacite jadeite from Myanmar jadeite mining area were studied by X-ray powder diffraction(XRD), X-ray fluorescence spectra(XRF), Raman spectra(RM) and UV-Vis Spectroscopy, etc. Based on testing by XRD and XRF, it was shown that it belongs to iron-enriched plagioclase, including albite and anorthite. The compositions range is between Ab0.731 An0.264 Or0.004 and Ab0.693 An0.303 Or0.004. Raman spectra of samples, albite jade and anorthite were collected and analyzed. Additionally, the distributions of Si, Al in the crystal structure were also discussed. UV-Vis spectra showed that dark green hue of this mineral is associated with d--d electronic transition of Fe3+ and Cr3+.

  11. Microwave spectra of some volatile organic compounds

    NASA Technical Reports Server (NTRS)

    White, W. F.

    1975-01-01

    A computer-controlled microwave (MRR) spectrometer was used to catalog reference spectra for chemical analysis. Tables of absorption frequency, peak absorption intensity, and integrated intensity are included for 26 volatile organic compounds, all but one of which contain oxygen.

  12. Frequency Spectra of Magnetoacoustic Emission in Meteorites

    NASA Astrophysics Data System (ADS)

    Ivanchenko, S. V.; Grokhovsky, V. I.; Kolchanov, N. N.

    2016-08-01

    We analyzed the magnetoacoustic emission spectra of iron meteorites and their industrial analogs. The revealed differences in signal amplitude, position and width of the peaks are associated with the features of structure and the magnetic texture.

  13. Contribution to the study of turbulence spectra

    NASA Technical Reports Server (NTRS)

    Dumas, R.

    1979-01-01

    An apparatus suitable for turbulence measurement between ranges of 1 to 5000 cps and from 6 to 16,000 cps was developed and is described. Turbulence spectra downstream of the grills were examined with reference to their general characteristics, their LF qualities, and the effects of periodic turbulence. Medium and HF are discussed. Turbulence spectra in the boundary layers are similarly examined, with reference to their fluctuations at right angles to the wall, and to lateral fluctuations. Turbulence spectra in a boundary layer with suction to the wall is discussed. Induced turbulence, and turbulence spectra at high Reynolds numbers. Calculations are presented relating to the effect of filtering on the value of the correlations in time and space.

  14. Comparing Ultraviolet Spectra Against Calculations: First Results

    NASA Technical Reports Server (NTRS)

    Peterson, Ruth C.

    2003-01-01

    The five-year goal of this effort is to calculate high fidelity mid-UV spectra for individual stars and stellar systems for a wide range of ages, abundances, and abundance ratios. In this first year, the emphasis was placed on revising the list of atomic line parameters used to calculate mid-UV spectra. First, new identifications of atomic lines and measurements of their transition probabilities were obtained for lines of the first and second ionization stages of iron-peak elements. Second, observed mid-UV and optical spectra for standard stars were re-analyzed and compared to new calculations, to refine the determination of transition probabilities and to estimate the identity of lines still missing from the laboratory lists. As evidenced by the figures, a dramatic improvement has resulted in the reproduction of the spectra of standard stars by the calculations.

  15. Defective transient endogenous spleen colony formation in S1/S1d mice.

    PubMed

    Wiktor-Jedrzejczak, W; Ahmed, A; Sharkis, S J; McKee, A; Sell, K W

    1979-04-01

    WCB6F1 mice of the genotype S1/S1d did not form transient 5-day endogenous spleen colonies following midlethal irradiation, either spontaneously or in response to postirradiation bleeding. Their hematologically normal (+/+) littermates produced colonies equivalent in number and morphologic type to a normal strain (D2B6F1), as evaluated by both macroscopic and microscopic criteria. Bone marrow cells from S1/S1d mice, when transplanted into lethally irradiated +/+ mice, were able to generate equivalent numbers of transient endogenous spleen colonies (TE-CFUs), as compared to that obtained when syngeneic +/+ marrow cells were injected into lethally irradiated +/+ recipients. A defective growth of an early class of hematopoietic progenitor cells, resulting in the clinical course of the S1/S1d anemia is suggested and confirms previous reports on the microenvironmental nature of this abnormality.

  16. CDK8-Mediated STAT1-S727 Phosphorylation Restrains NK Cell Cytotoxicity and Tumor Surveillance

    PubMed Central

    Putz, Eva Maria; Gotthardt, Dagmar; Hoermann, Gregor; Csiszar, Agnes; Wirth, Silvia; Berger, Angelika; Straka, Elisabeth; Rigler, Doris; Wallner, Barbara; Jamieson, Amanda M.; Pickl, Winfried F.; Zebedin-Brandl, Eva Maria; Müller, Mathias; Decker, Thomas; Sexl, Veronika

    2013-01-01

    Summary The transcription factor STAT1 is important in natural killer (NK) cells, which provide immediate defense against tumor and virally infected cells. We show that mutation of a single phosphorylation site (Stat1-S727A) enhances NK cell cytotoxicity against a range of tumor cells, accompanied by increased expression of perforin and granzyme B. Stat1-S727A mice display significantly delayed disease onset in NK cell-surveilled tumor models including melanoma, leukemia, and metastasizing breast cancer. Constitutive phosphorylation of S727 depends on cyclin-dependent kinase 8 (CDK8). Inhibition of CDK8-mediated STAT1-S727 phosphorylation may thus represent a therapeutic strategy for stimulating NK cell-mediated tumor surveillance. PMID:23933255

  17. Optical frequency measurement of the 1S-3S two-photon transition in hydrogen

    NASA Astrophysics Data System (ADS)

    Arnoult, O.; Nez, F.; Julien, L.; Biraben, F.

    2010-11-01

    This article reports the first optical frequency measurement of the 1S-3S transition in hydrogen. The excitation of this transition occurs at a wavelength of 205 nm which is obtained with two frequency doubling stages of a titanium sapphire laser at 820 nm. Its frequency is measured with an optical frequency comb. The second-order Doppler effect is evaluated from the observation of the motional Stark effect due to a transverse magnetic field perpendicular to the atomic beam. The measured value of the 1S_{1/2}( F = 1)-3S1/2( F = 1) frequency splitting is 2 922 742 936.729(13) MHz with a relative uncertainty of 4.5 × 10-12. After the measurement of the 1S-2S frequency, this result is the most precise of the optical frequencies in hydrogen.

  18. POLLUX: a database of synthetic stellar spectra

    NASA Astrophysics Data System (ADS)

    Palacios, A.; Gebran, M.; Josselin, E.; Martins, F.; Plez, B.; Belmas, M.; Lèbre, A.

    2010-06-01

    Aims: Synthetic spectra are needed to determine fundamental stellar and wind parameters of all types of stars. They are also used for the construction of theoretical spectral libraries helpful for stellar population synthesis. Therefore, a database of theoretical spectra is required to allow rapid and quantitative comparisons to spectroscopic data. We provide such a database offering an unprecedented coverage of the entire Hertzsprung-Russell diagram. Methods: We present the POLLUX database of synthetic stellar spectra. For objects with Teff ≤ 6000 K, MARCS atmosphere models are computed and the program TURBOSPECTRUM provides the synthetic spectra. ATLAS12 models are computed for stars with 7000 K ≤ Teff ≤ 15 000 K. SYNSPEC gives the corresponding spectra. Finally, the code CMFGEN provides atmosphere models for the hottest stars (Teff > 25 000 K). Their spectra are computed with CMF_FLUX. Both high resolution (R > 150 000) optical spectra in the range 3000 to 12 000 Å and spectral energy distributions extending from the UV to near-IR ranges are presented. These spectra cover the HR diagram at solar metallicity. Results: We propose a wide variety of synthetic spectra for various types of stars in a format that is compliant with the Virtual Observatory standards. A user-friendly web interface allows an easy selection of spectra and data retrieval. Upcoming developments will include an extension to a large range of metallicities and to the near-IR high resolution spectra, as well as a better coverage of the HR diagram, with the inclusion of models for Wolf-Rayet stars and large datasets for cool stars. The POLLUX database is accessible at http://pollux.graal.univ-montp2.fr/ and through the Virtual Observatory. Copy of database is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb

  19. Diffuse emission and pathological Seyfert spectra

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.

    1995-01-01

    In this annual ROSAT status report, the diffuse emission and spectra from Seyfert galaxies are examined. Three papers are presented and their contents include the soft x-ray properties and spectra of a binary millisecond pulsar, the PSPC and HRI observations of a Starburst/Seyfert 2 Galaxy, and an analysis of the possibility of x-ray luminous starbursts in the Einstein Medium Sensitivity Survey.

  20. On the Photoelectron Spectra of Li4

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)

    1996-01-01

    The most stable structure for Li4(-) is found to be the rhombus. Electron detachment from this structure does not seem able to fully explain the photoelectron spectra. The computed results are consistent with those Rao, Jena, and Ray who have proposed that the experimental spectra consists of a superposition of detachment from the Li4(-) rhombus and tetrahedron, forming the singlet and triplet states of Li4, respectively.

  1. New atlas of IR solar spectra

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Blatherwick, R. D.; Murcray, F. H.; Vanallen, J. W.; Bradford, C. M.; Cook, G. R.; Murcray, D. G.

    1980-01-01

    Over 4500 absorption lines have been marked on the spectra and the corresponding line positions tabulated. The associated absorbing telluric or solar species for more than 90% of these lines have been identified and only a fraction of the unidentified lines have peak absorptions greater than a few percent. The high resolution and the low Sun spectra greatly enhance the sensitivity limits for identification of trace constituents.

  2. Trigonometric Polynomials For Estimation Of Spectra

    NASA Technical Reports Server (NTRS)

    Greenhall, Charles A.

    1990-01-01

    Orthogonal sets of trigonometric polynomials used as suboptimal substitutes for discrete prolate-spheroidal "windows" of Thomson method of estimation of spectra. As used here, "windows" denotes weighting functions used in sampling time series to obtain their power spectra within specified frequency bands. Simplified windows designed to require less computation than do discrete prolate-spheroidal windows, albeit at price of some loss of accuracy.

  3. Analytical calculation of two-dimensional spectra.

    PubMed

    Bell, Joshua D; Conrad, Rebecca; Siemens, Mark E

    2015-04-01

    We demonstrate an analytical calculation of two-dimensional (2D) coherent spectra of electronic or vibrational resonances. Starting with the solution to the optical Bloch equations for a two-level system in the 2D time domain, we show that a fully analytical 2D Fourier transform can be performed if the projection-slice and Fourier-shift theorems of Fourier transforms are applied. Results can be fit to experimental 2D coherent spectra of resonances with arbitrary inhomogeneity.

  4. THE SPITZER ATLAS OF STELLAR SPECTRA (SASS)

    SciTech Connect

    Ardila, David R.; Van Dyk, Schuyler D.; Makowiecki, Wojciech; Stauffer, John; Rho, Jeonghee; Fajardo-Acosta, Sergio; Hoard, D. W.; Wachter, Stefanie; Song, Inseok

    2010-12-15

    We present the Spitzer Atlas of Stellar Spectra, which includes 159 stellar spectra (5-32 {mu}m; R {approx} 100) taken with the Infrared Spectrograph on the Spitzer Space Telescope. This Atlas gathers representative spectra of a broad section of the Hertzsprung-Russell diagram, intended to serve as a general stellar spectral reference in the mid-infrared. It includes stars from all luminosity classes, as well as Wolf-Rayet (WR) objects. Furthermore, it includes some objects of intrinsic interest, such as blue stragglers and certain pulsating variables. All of the spectra have been uniformly reduced, and all are available online. For dwarfs and giants, the spectra of early-type objects are relatively featureless, characterized by the presence of hydrogen lines in A spectral types. Besides these, the most noticeable photospheric features correspond to water vapor and silicon monoxide in late-type objects and methane and ammonia features at the latest spectral types. Most supergiant spectra in the Atlas present evidence of circumstellar gas and/or dust. The sample includes five M supergiant spectra, which show strong dust excesses and in some cases polycyclic aromatic hydrocarbon features. Sequences of WR stars present the well-known pattern of lines of He I and He II, as well as forbidden lines of ionized metals. The characteristic flat-top shape of the [Ne III] line is evident even at these low spectral resolutions. Several Luminous Blue Variables and other transition stars are present in the Atlas and show very diverse spectra, dominated by circumstellar gas and dust features. We show that the [8]-[24] Spitzer colors (IRAC and MIPS) are poor predictors of spectral type for most luminosity classes.

  5. On optimization of absorption-dispersion spectra

    NASA Astrophysics Data System (ADS)

    Hawranek, J. P.; Grabska, J.; Beć, K. B.

    2016-12-01

    A modified approach to the analysis of spectra of the complex electric permittivity of liquids in the Infrared region is presented. These spectra are derived from experimental spectra of the complex refractive index. Subsequently they are used to determine important secondary quantities, e.g. spectra of complex molecular polarizabilities and an integral property - the molar vibrational polarization. The accuracy of these quantities depends essentially on the accuracy of both components of the complex electric permittivity spectrum. In the proposed procedure, the spectra of the complex electric permittivity are approximated using the Classical Damped Harmonic Oscillator (CDHO) model for the description of individual bandshapes. The CDHO model defines both the real and imaginary part of the complex permittivity. The fitting procedure includes a simultaneous optimization of both the real and imaginary parts of the complex permittivity spectrum. A comparison of absorption-only curve fitting and the novel absorption-dispersion double curve fitting is presented; advantages of the new approach in accuracy, reliability and convergence time are pointed out. Due to the complexity of the problem, the choice was restricted to non-gradient methods of optimization. The performance of several gradientless algorithms was tested. Among numerous procedures the Powell General Least Squares Method Without Derivatives was found to be the most efficient. The reliability of obtained results of the band separatiovn process was tested on several simulated spectra of increasing complexity. The applicability of the developed approach to the analysis of exemplary experimental data was evaluated and discussed.

  6. ToF-SIMS and XPS Characterization of Protein Films Adsorbed onto Bare and Sodium Styrenesulfonate-Grafted Gold Substrates.

    PubMed

    Foster, Rami N; Harrison, Elisa T; Castner, David G

    2016-04-05

    The adsorption of single-component bovine serum albumin (BSA), bovine fibrinogen (Fgn), and bovine immunoglobulin G (IgG) films as well as multicomponent bovine plasma films onto bare and sodium styrenesulfonate (NaSS)-grafted gold substrates was characterized. The adsorption isotherms, measured via X-ray photoelectron spectroscopy, showed that at low solution concentrations all three single-component proteins adsorb with higher affinity onto gold surfaces compared to NaSS surfaces. However, at higher concentrations, NaSS surfaces adsorb the same or more total protein than gold surfaces. This may be because proteins that adsorb onto NaSS undergo structural rearrangements, resulting in a larger fraction of irreversibly adsorbed species over time. Still, with the possible exception of BSA adsorbed onto gold, neither surface appeared to have saturated at the highest protein solution concentration studied. Principal component (PC) analysis of amino acid mass fragments from time-of-flight secondary ion mass spectra distinguished between the same protein adsorbed onto NaSS and gold surfaces, suggesting that proteins adsorb differently on NaSS and gold surfaces. Explored further using peak ratios for buried/surface amino acids for each protein, we found that proteins denature more on NaSS surfaces than on gold surfaces. Also, using peak ratios for asymmetrically distributed amino acids, potential structural differences were postulated for BSA and IgG adsorbed onto NaSS and gold surfaces. PC modeling, used to track changes in plasma adsorption with time, suggests that plasma films on NaSS and Au surfaces become more Fgn-like with increasing adsorption time. However, the PC models included only three proteins, where plasma is composed of hundreds of proteins. Therefore, while both gold and NaSS appear to adsorb more Fgn with time, further study is required to confirm that this is representative of the final state of the plasma films.

  7. FTIR and XPS analysis of the changes in bamboo chemical structure decayed by white-rot and brown-rot fungi

    NASA Astrophysics Data System (ADS)

    Xu, Guoqi; Wang, Lihai; Liu, Junliang; Wu, Jinzhuo

    2013-09-01

    In order to investigate different types of decay mechanisms in bamboo (Phyllostachys edulis), the chemical structure and microstructure of bamboo samples decayed by P. chrysosporium (White-rot) and G. trabeum (Brown-rot) for 12 weeks were studied. The analysis methods include fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron spectroscopy (SEM). By using the SEM method, it was found that attacks to parenchyma cells and places near the inner skin of bamboo were the most frequent and the vessels were the primary paths for the spread of mycelium in the bamboo. FTIR and XPS results showed that the crystallinity (I1425/I896) of bamboo decreased after being decayed by these two fungi and the crystalline cellulose in bamboo was degraded. The white-rot P. chrysosporium had stronger degradability on lignin compared to hemicellulose and cellulose in bamboo. And the brown-rot G. trabeum had preferential degradability on hemicellulose fraction over cellulose and lignin. Oxidation and hydrolysis surface reactions occurred during the process of decay, but the reaction rates for cellulose and lignin were different.

  8. The behavior of f-levels in hcp and bcc rare-earth elements in the ground state and XPS and BIS spectroscopy from density-functional theory.

    PubMed

    Jarlborg, T

    2014-04-16

    The electronic structures of rare-earth elements in the hexagonal close-packed structure and Europium in the body-centered cubic structure are calculated using density-functional theory (DFT). X-ray photoemission spectroscopy (XPS) and bremsstrahlung isochromatic spectroscopy (BIS) simulations are made within DFT by implying that the f-electrons are excited by a large photon energy, either by removal from the occupied states in XPS or by addition to the unoccupied f-states in BIS. The results show sizable differences in the apparent position of the f-states compared to the f-band energy of the ground states. This result is fundamentally different from calculations assuming strong on-site correlation, since all the calculations are based on DFT. The spin-orbit coupling and multiplet splittings are not included, and the present simulation accounts for almost half of the difference between the f-level positions in the DFT ground states and the observed f-level positions. The electronic specific-heat at low T is compatible with the DFT ground state, where f-electrons often reside at the Fermi level.

  9. Vacancy ordered γ-Fe2O3 nanoparticles functionalized with nanohydroxyapatite: XRD, FTIR, TEM, XPS and Mössbauer studies

    NASA Astrophysics Data System (ADS)

    Ramos Guivar, Juan A.; Sanches, Edgar A.; Bruns, Florian; Sadrollahi, Elaheh; Morales, M. A.; López, Elvis O.; Litterst, F. Jochen

    2016-12-01

    Vacancy ordered maghemite (γ-Fe2O3) nanoparticles functionalized with nanohydroxyapatite (HAp - Ca10(PO4) 6(OH)2) have been successfully synthesized using an inexpensive co-precipitation chemical route. Evidence for the presence of vacancy order in maghemite was shown by the superstructure lines observed in X-ray diffraction. The adsorption of carboxyl groups of citric acid (C6H8O7) onto γ-Fe2O3 nanoparticles was investigated by FTIR, XPS and Mössbauer spectroscopy. From XPS surface analysis, two binding energies related to oxygen were attributed to bindings between C6H8O7/γ- Fe2O3 and C6H8O7/HAp from an interfacial reaction promoted by strongly adsorbed H2O molecules at the surface of these nanomaterials. Le Bail refinement of the XRD patterns showed the formation of well-crystallized pure tetragonal maghemite before and after functionalization with nanoHAp. The temperature dependence of hyperfine parameters of pure and functionalized γ-Fe2O3 nanoparticles was investigated via Mössbauer spectroscopy. TEM revealed the formation of quasi-spherical γ- Fe2O3 nanoparticles with an average diameter of ca. 12 nm and 16 nm before and after functionalization with nanoHAp in agreement with Le Bail refinement. Magnetometry measurements showed a saturation magnetization of 12 emu/g and a blocking temperature of 340 K for the functionalized γ- Fe2O3 nanoparticles.

  10. [SIMS (secondary ion mass spectroscopy) and XPS (x-ray photoelectron spectroscopy) study of titanium implant surfaces coated with anodic titanium-oxide layer].

    PubMed

    Suba, Csongor; Velich, Norbert; Vida, György; Kovács, Lajos; Kiss, Gábor; Szabó, György

    2003-10-01

    The demands that must be satisfied by titanium implants applied in medical practice include chemical and physical durability. An anodic oxide protective layer formed on the surface of titanium implants serves for the better attainment of this aim. The composition of the passivizing layer and the changes in its thickness and binding state can be studied by method of material science, e.g. by secondary ion mass spectroscopy (SIMS) and X-ray photoelectron spectroscopy (XPS). In this way a possibility arises for the material technological classification of the Ti-TiO2 layer structure and for the observation of the physical and chemical reactions that occur between the implants and the tissues in the organism. The present XPS examinations revealed that the binding state of the titanium forming the surface of the plates involve neither significant quantities of titanium oxide nor impurities. In the SIMS investigation the thickness of the titanium oxide layer was found to be 120-150 nm. Determination of the thickness of the surface, the binding state of the titanium and the exact proportions of the impurities and additives furnishes a possibility for a subsequent comparison with the surface structure of plates removed from the organism. It is important for the assessment of the practical value of the protective layer.

  11. Composition and evolution of the solid-electrolyte interphase in Na2Ti3O7 electrodes for Na-ion batteries: XPS and Auger parameter analysis.

    PubMed

    Muñoz-Márquez, Miguel A; Zarrabeitia, Maider; Castillo-Martínez, Elizabeth; Eguía-Barrio, Aitor; Rojo, Teófilo; Casas-Cabanas, Montse

    2015-04-15

    Na2Ti3O7 is considered a promising negative electrode for Na-ion batteries; however, poor capacity retention has been reported and the stability of the solid-electrolyte interphase (SEI) could be one of the main actors of this underperformance. The composition and evolution of the SEI in Na2Ti3O7 electrodes is hereby studied by means of X-ray photoelectron spectroscopy (XPS). To overcome typical XPS limitations in the photoelectron energy assignments, the analysis of the Auger parameter is here proposed for the first time in battery materials characterization. We have found that the electrode/electrolyte interface formed upon discharge, mostly composed by carbonates and semicarbonates (Na2CO3, NaCO3R), fluorides (NaF), chlorides (NaCl) and poly(ethylene oxide)s, is unstable upon electrochemical cycling. Additionally, solid state nuclear magnetic resonance (NMR) studies prove the reaction of the polyvinylidene difluoride (PVdF) binder with sodium. The powerful approach used in this work, namely Auger parameter study, enables us to correctly determine the composition of the electrode surface layer without any interference from surface charging or absolute binding energy calibration effects. As a result, the suitability for Na-ion batteries of binders and electrolytes widely used for Li-ion batteries is questioned here.

  12. Soft electronic structure modulation of surface (thin-film) and bulk (ceramics) morphologies of TiO2-host by Pb-implantation: XPS-and-DFT characterization

    NASA Astrophysics Data System (ADS)

    Zatsepin, D. A.; Boukhvalov, D. W.; Gavrilov, N. V.; Zatsepin, A. F.; Shur, V. Ya.; Esin, A. A.; Kim, S. S.; Kurmaev, E. Z.

    2017-04-01

    The results of combined experimental and theoretical study of substitutional and clustering effects in the structure of Pb-doped TiO2-hosts (bulk ceramics and thin-film morphologies) are presented. Pb-doping of the bulk and thin-film titanium dioxide was made with the help of pulsed ion-implantation without posterior tempering (Electronic Structure Modulation Mode). The X-ray photoelectron spectroscopy (XPS) qualification of core-levels and valence bands and Density-Functional Theory (DFT) calculations were employed in order to study the yielded electronic structure of Pb-ion modulated TiO2 host-matrices. The combined XPS-and-DFT analysis has agreed definitely with the scenario of the implantation stimulated appearance of PbO-like structures in the bulk morphology of TiO2:Pb, whereas in thin-film morphology the PbO2-like structure becomes dominating, essentially contributing weak O/Pb bonding (PbxOy defect clusters). The crucial role of the oxygen hollow-type vacancies for the process of Pb-impurity "insertion" into the structure of bulk TiO2 was pointed out employing DFT-based theoretical background. Both experiment and theory established clearly the final electronic structure re-arrangement of the bulk and thin-film morphologies of TiO2 because of the Pb-modulated deformation and shift of the initial Valence Base-Band Width about 1 eV up.

  13. A ToF-SIMS and XPS study of protein adsorption and cell attachment across PEG-like plasma polymer films with lateral compositional gradients

    NASA Astrophysics Data System (ADS)

    Menzies, Donna J.; Jasieniak, Marek; Griesser, Hans J.; Forsythe, John S.; Johnson, Graham; McFarland, Gail A.; Muir, Benjamin W.

    2012-12-01

    In this work we report a detailed X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) study of poly(ethylene glycol) PEG-like chemical gradients deposited via plasma enhanced chemical vapour deposition (PECVD) at two different load powers using diethylene glycol dimethyl ether (DG) as a monomer. Principal component analysis (PCA) was applied to the ToF-SIMS data both before and after protein adsorption on the plasma polymer thin films. Results of the PCA loadings indicated a higher content of hydrocarbon fragments across the higher load power gradient, which adsorbed higher amounts of proteins. Gradients deposited at a lower load power retained a higher degree of monomer like functionality as did the central region directly underneath the knife edge electrode. Analysis of the adsorption of serum proteins (human serum albumin and fetal bovine serum) was monitored across the gradient films and increased with decreasing ether (PEG-like) film chemistries. The effect of protein incubation time on the levels adsorbed fetal bovine serum on the plasma polymer films was critical, with significantly more protein adsorbing after 24 hour incubation times on both gradient films. The attachment of HeLa cells on the gradients appeared to be dictated not only by the surface chemistry, but also by the adsorption of serum proteins. XPS analysis revealed that at surface ether concentrations of less than 70% in the gradient films, significant increases in protein and cell attachment were observed.

  14. Americium(III) capture using phosphonic acid-functionalized silicas with different mesoporous morphologies: adsorption behavior study and mechanism investigation by EXAFS/XPS.

    PubMed

    Zhang, Wen; He, Xihong; Ye, Gang; Yi, Rong; Chen, Jing

    2014-06-17

    Efficient capture of highly toxic radionuclides with long half-lives such as Americium-241 is crucial to prevent radionuclides from diffusing into the biosphere. To reach this purpose, three different types of mesoporous silicas functionalized with phosphonic acid ligands (SBA-POH, MCM-POH, and BPMO-POH) were synthesized via a facile procedure. The structure, surface chemistry, and micromorphology of the materials were fully characterized by (31)P/(13)C/(29)Si MAS NMR, XPS, and XRD analysis. Efficient adsorption of Am(III) was realized with a fast rate to reach equilibrium (within 10 min). Influences including structural parameters and functionalization degree on the adsorption behavior were investigated. Slope analysis of the equilibrium data suggested that the coordination with Am(III) involved the exchange of three protons. Moreover, extended X-ray absorption fine structure (EXAFS) analysis, in combination with XPS survey, was employed for an in-depth probe into the binding mechanism by using Eu(III) as a simulant due to its similar coordination behavior and benign property. The results showed three phosphonic acid ligands were coordinated to Eu(III) in bidentate fashion, and Eu(P(O)O)3(H2O) species were formed with the Eu-O coordination number of 7. These phosphonic acid-functionalized mesoporous silicas should be promising for the treatment of Am-containing radioactive liquid waste.

  15. Use of XPS to identify the oxidation state of Mn in solid surfaces of filtration media oxide samples from drinking water treatment plants.

    PubMed

    Cerrato, José M; Hochella, Michael F; Knocke, William R; Dietrich, Andrea M; Cromer, Thomas F

    2010-08-01

    X-ray photoelectron spectroscopy (XPS) was used to identify Mn(II), Mn(III), and Mn(IV) in the surfaces of pure oxide standards and filtration media samples from drinking water treatment plants through the determination of the magnitude of the Mn 3s multiplet splitting and the position and shape of the Mn 3p photo-line. The Mn 3p region has been widely studied by applied physicists and surface scientists, but its application to identify the oxidation state of Mn in heterogeneous oxide samples has been limited. This study shows that the use of both the Mn 3s multiplet splitting and the position and shape of the Mn 3p photo-line provides a feasible means of determining the oxidation state of manganese in complex heterogeneous, environmentally important samples. Surface analysis of filtration media samples from several drinking water treatment plants was conducted. While Mn(IV) was predominant in most samples, a mixture of Mn(III) and Mn(IV) was also identified in some of the filtration media samples studied. The predominance of Mn(IV) in the media samples was felt to be related to the maintenance of free chlorine (HOCl) at substantial concentrations (2-5 mg*L(-1) as Cl2) across these filters. XPS could be a useful tool to further understand the specific mechanisms affecting soluble Mn removal using MnOx-coated filtration media.

  16. Self assembling monolayers of dialkynyl bridged Pd(II) thiols obtained by thermally induced multilayer desorption: Thermal and chemical stability investigated by SR-XPS

    NASA Astrophysics Data System (ADS)

    Battocchio, C.; Fratoddi, I.; Bondino, F.; Malvestuto, M.; Russo, M. V.; Polzonetti, G.

    2012-02-01

    Self assembling monolayers (SAMs) of organometallic thiols trans-[HS-Pd(PBu3)2-SH], trans-[HS-Pd(PBu3)2(-Ctbnd C-C6H5)] and trans,trans-[HS-Pd(PBu3)2(-Ctbnd C-C6H4-C6H4-Ctbnd C-Pd(PBu3)2-SH] on gold were obtained from the corresponding multilayers through thermally induced desorption. Temperature-dependent synchrotron radiation-induced X-ray photoelectron spectroscopy (SR-XPS) measurements were carried out on the heated multilayers during the annealing process, in order to investigate the thermal and chemical stability of the systems. SAMs of the same organometallic thiols were also obtained by rinsing the thick films with appropriate solvents. SR-XPS was used to ascertain that the molecular and electronic structure of the two series of SAMs are not influenced by the rinsing or thermal desorption process, i.e. both strategies allow for obtaining well ordered monolayers of organometallic thiols.

  17. XPS, UV-vis spectroscopy and AFM studies on removal mechanisms of Si-face SiC wafer chemical mechanical polishing (CMP)

    NASA Astrophysics Data System (ADS)

    Zhou, Yan; Pan, Guoshun; Shi, Xiaolei; Xu, Li; Zou, Chunli; Gong, Hua; Luo, Guihai

    2014-10-01

    Chemical mechanical polishing (CMP) removal mechanisms of on-axis Si-face SiC wafer have been investigated through X-ray photoelectron spectroscopy (XPS), UV-visible (UV-vis) spectroscopy and atomic force microscopy (AFM). XPS results indicate that silicon oxide is formed on Si-face surface polished by the slurry including oxidant H2O2, but not that after immersing in H2O2 solution. UV-vis spectroscopy curves prove that •OH hydroxyl radical could be generated only under CMP polishing by the slurry including H2O2 and abrasive, so as to promote oxidation of Si-face to realize the effective removal; meanwhile, alkali KOH during CMP could induce the production of more radicals to improve the removal. On the other side, ultra-smooth polished surface with atomic step structure morphology and extremely low Ra of about 0.06 nm (through AFM) is obtained using the developed slurry with silica nanoparticle abrasive. Through investigating the variations of the atomic step morphology on the surface polished by different slurries, it's reveals that CMP removal mechanism involves a simultaneous process of surface chemical reaction and nanoparticle atomic scale abrasion.

  18. X-ray emission and photoelectron spectra of Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3}

    SciTech Connect

    Kurmaev, E.Z.; Korotin, M.A.; Galakhov, V.R.; Finkelstein, L.D.; Zabolotzky, E.I.; Efremova, N.N.; Lobachevskaya, N.I.; Stadler, S.; Ederer, D.L.; Callcott, T.A.; Zhou, L.; Moewes, A.; Bartkowski, S.; Neumann, M.; Matsuno, J.; Mizokawa, T.; Fujimori, A.; Mitchell, J.

    1999-05-01

    The results of measurements of x-ray photoelectron (XPS), x-ray emission (XES), and x-ray absorption spectra and local spin-density approximation band structure (LSDA) calculations of Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} are presented. The excitation energy dependence of Mn L{sub 2,3} and O K{alpha} x-ray emission spectra of Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} is measured using tunable synchrotron radiation. The XES measurements yielded no photon energy dependence for the O K{alpha} spectra, but the Mn L{sub 2,3} spectra yielded inelastic scattering losses of 2 and 6 eV, corresponding to features in the structure of the occupied part of the valence band. Comparing XPS and XES measurements with LSDA band-structure calculations, one concludes that the electronic structure of the compound consists mainly of Mn 3d and O 2p states. States of 3d character localized at the Mn site predominate near the top of the valence band (VB). Some differences in the Mn 3d distribution in this part of the XPS valence band and Mn L{sub 3} XES with {ital d} symmetry due to spin-selection rules that govern the Mn L{sub 3} XES. In addition, the Mn 3d states distribution is hybridized with the O 2p part of the VB. Mn L{sub 3} XES spectra were determined relative to the Fermi energy by assuming normal x-ray emission begins from the lowest level of the p{sup 5}d{sup n+1}L intermediate state (which is the Mn 2p ionizatation threshold). From the local spin-density approximation, the orbital character of the Mn 3d electrons can be assigned e{sub g} symmetry at the top of the valence band T{sub 2g} in the central part of the VB, and equal contributions of e{sub g} and t{sub 2g} states at the bottom of the valence band. {copyright} {ital 1999} {ital The American Physical Society}

  19. The elusive S2 state, the S1/S2 splitting, and the excimer states of the benzene dimer.

    PubMed

    Balmer, Franziska A; Trachsel, Maria A; van der Avoird, Ad; Leutwyler, Samuel

    2015-06-21

    We observe the weak S0 → S2 transitions of the T-shaped benzene dimers (Bz)2 and (Bz-d6)2 about 250 cm(-1) and 220 cm(-1) above their respective S0 → S1 electronic origins using two-color resonant two-photon ionization spectroscopy. Spin-component scaled (SCS) second-order approximate coupled-cluster (CC2) calculations predict that for the tipped T-shaped geometry, the S0 → S2 electronic oscillator strength fel(S2) is ∼10 times smaller than fel(S1) and the S2 state lies ∼240 cm(-1) above S1, in excellent agreement with experiment. The S0 → S1 (ππ(∗)) transition is mainly localized on the "stem" benzene, with a minor stem → cap charge-transfer contribution; the S0 → S2 transition is mainly localized on the "cap" benzene. The orbitals, electronic oscillator strengths fel(S1) and fel(S2), and transition frequencies depend strongly on the tipping angle ω between the two Bz moieties. The SCS-CC2 calculated S1 and S2 excitation energies at different T-shaped, stacked-parallel and parallel-displaced stationary points of the (Bz)2 ground-state surface allow to construct approximate S1 and S2 potential energy surfaces and reveal their relation to the "excimer" states at the stacked-parallel geometry. The fel(S1) and fel(S2) transition dipole moments at the C2v-symmetric T-shape, parallel-displaced and stacked-parallel geometries are either zero or ∼10 times smaller than at the tipped T-shaped geometry. This unusual property of the S0 → S1 and S0 → S2 transition-dipole moment surfaces of (Bz)2 restricts its observation by electronic spectroscopy to the tipped and tilted T-shaped geometries; the other ground-state geometries are impossible or extremely difficult to observe. The S0 → S1/S2 spectra of (Bz)2 are compared to those of imidazole ⋅ (Bz)2, which has a rigid triangular structure with a tilted (Bz)2 subunit. The S0 → S1/ S2 transitions of imidazole-(benzene)2 lie at similar energies as those of (Bz)2, confirming our assignment of the

  20. Structural investigation on Ge{sub x}Sb{sub 10}Se{sub 90−x} glasses using x-ray photoelectron spectra

    SciTech Connect

    Wei, Wen-Hou; Xiang, Shen; Xu, Si-Wei; Wang, Rong-Ping; Fang, Liang

    2014-05-14

    The structure of Ge{sub x}Sb{sub 10}Se{sub 90−x} glasses (x = 7.5, 10, 15, 20, 25, 27.5, 30, and 32.5 at. %) has been investigated by x-ray photoelectron spectroscopy (XPS). Different structural units have been extracted and characterized by decomposing XPS core level spectra, the evolution of the relative concentration of each structural unit indicates that, the relative contributions of Se-trimers and Se-Se-Ge(Sb) structure decrease with increasing Ge content until they become zero at chemically stoichiometric glasses of Ge{sub 25}Sb{sub 10}Se{sub 65}, and then the homopolar bonds like Ge-Ge and Sb-Sb begin to appear in the spectra. Increase of homopolar bonds will extend band-tails into the gap and narrow the optical band gap. Thus, the glass with a stoichiometric composition generally has fewer defective bonds and larger optical bandgap.

  1. Studies of Υ(1S) bottomonium state production at the Tevatron Collider Experiment D0

    SciTech Connect

    Huang, Jundong

    2004-11-01

    The production of heavy quarkonium in hadronic collisions provides an ideal testing ground for our understanding of the production mechanisms for heavy quarks and the non-perturbative QCD effects that bind the quark pairs into quarkonium. In this analysis, the inclusive production cross section of the Υ(1S) bottomonium state is measured using the Υ(1S) → μ+μ- decay mode. The data sample corresponds to an integrated luminosity of 159.1 ± 10.3 pb-1. We determine differential cross sections as functions of the Υ(1S) transverse momentum, pTΥ, for three ranges of the Υ(1S) rapidity: 0 < |yΥ| < 0.6,0.6 < |yΥ| < 1.2 and 1.2 < |yΥ| < 1.8. The shapes of dσ/dpT cross sections show little variation with rapidity and are consistent with the published Run I CDF measurement over the rapidity range |yΥ| < 0.4.

  2. SKI-1/S1P inhibitor PF-429242 impairs the onset of HCV infection.

    PubMed

    Blanchet, Matthieu; Sureau, Camille; Guévin, Carl; Seidah, Nabil G; Labonté, Patrick

    2015-03-01

    Worldwide, approximately 170 million individuals are afflicted with chronic hepatitis C virus (HCV) infection. To prevent the development of inherent diseases such as cirrhosis and hepatocellular carcinoma, tremendous efforts have been made, leading to the development of promising new treatments. However, their efficiency is still dependent on the viral genotype. Additionally, these treatments that target the virus directly can trigger the emergence of resistant variants. In a previous study, we have demonstrated that a long-term (72h) inhibition of SKI-1/S1P, a master lipogenic pathway regulator through activation of SREBP, resulted in impaired HCV genome replication and infectious virion secretion. In the present study, we sought to investigate the antiviral effect of the SKI-1/S1P small molecule inhibitor PF-429242 at the early steps of the HCV lifecycle. Our results indicate a very potent antiviral effect of the inhibitor early in the viral lifecycle and that the overall action of the compound relies on two different contributions. The first one is SREBP/SKI-1/S1P dependent and involves LDLR and NPC1L1 proteins, while the second one is SREBP independent. Overall, our study confirms that SKI-1/S1P is a relevant target to impair HCV infection and that PF-429242 could be a promising candidate in the field of HCV infection treatment.

  3. Recognition of disturbances with specified morphology in time series: Part 2. Spikes on 1-s magnetograms

    NASA Astrophysics Data System (ADS)

    Soloviev, A. A.; Agayan, S. M.; Gvishiani, A. D.; Bogoutdinov, Sh. R.; Chulliat, A.

    2012-05-01

    Preliminary magnetograms contain different types of temporal anthropogenic disturbances: spikes, baseline jumps, drifts, etc. These disturbances should be identified and filtered out during the preprocessing of the preliminary records for the definitive data. As of now, at the geomagnetic observatories, such filtering is carried out manually. Most of the disturbances in the records sampled every second are spikes, which are much more abundant than those on the magnetograms sampled every minute. Another important feature of the 1-s magnetograms is the presence of a plenty of specific disturbances caused by short-period geomagnetic pulsations, which must be retained in the definitive records. Thus, creating an instrument for formalized and unified recognition of spikes on the preliminary 1-s magnetograms would largely solve the problem of labor-consuming manual preprocessing of the magnetic records. In the context of this idea, in the present paper, we focus on recognition of the spikes on the 1-s magnetograms as a key point of the problem. We describe here the new algorithm of pattern recognition, SPs, which is capable of automatically identifying the spikes on the 1-s magnetograms with a low probability of missed events and false alarms. The algorithm was verified on the real magnetic data recorded at the French observatory located on Easter Island in the Pacific.

  4. Xbp1s in Pomc neurons connects ER stress with energy balance and glucose homeostasis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The molecular mechanisms underlying neuronal leptin and insulin resistance in obesity and diabetes remain unclear. Here we show that induction ofthe unfolded protein response transcription factor spliced X-box binding protein 1(Xbp1s) in pro-opio-melanocortin (Pomc) neurons alone is sufficient to pr...

  5. Methods of using (1S,3S)-3-amino-4-difluoromethylenyl-1-cyclopentanoic acid

    DOEpatents

    Silverman, Richard B; Dewey, Stephen L; Miller, Steven

    2015-03-03

    (1S,3S)-3-amino-4-difluoromethylenyl-1-cyclopentanoic acid also known as CPP-115 or its pharmaceutically acceptable salts can be used to treat addiction and neurological disorders such as epilepsy without side effects such as visual field defects caused by vigabatrin (Sabril).

  6. 3. N ELEVATION OF BUILDING 1'S E WING, SHOWING THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. N ELEVATION OF BUILDING 1'S E WING, SHOWING THE PILASTERS, TERRA COTTA PANELS, AND THE EGYPTIAN MOTIF DECORATIVE CORNICE ELEMENTS; LOOKING S. (Ryan) - Veterans Administration Medical Center, Building No. 1, Old State Route 13 West, Marion, Williamson County, IL

  7. 4. DETAIL VIEW OF NW CORNER OF BUILDING 1'S W ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. DETAIL VIEW OF NW CORNER OF BUILDING 1'S W WING, SHOWING THE PILASTERS, TERRA COTTA PANELS, AND THE EGYPTIAN MOTIF DECORATIVE CORNICE ELEMENTS; LOOKING ENE. (Harms) - Veterans Administration Medical Center, Building No. 1, Old State Route 13 West, Marion, Williamson County, IL

  8. A Dynamical Framework for the All-or-None G1/S Transition

    PubMed Central

    Barr, Alexis R.; Heldt, Frank S.; Zhang, Tongli; Bakal, Chris; Novák, Béla

    2016-01-01

    Summary The transition from G1 into DNA replication (S phase) is an emergent behavior resulting from dynamic and complex interactions between cyclin-dependent kinases (Cdks), Cdk inhibitors (CKIs), and the anaphase-promoting complex/cyclosome (APC/C). Understanding the cellular decision to commit to S phase requires a quantitative description of these interactions. We apply quantitative imaging of single human cells to track the expression of G1/S regulators and use these data to parametrize a stochastic mathematical model of the G1/S transition. We show that a rapid, proteolytic, double-negative feedback loop between Cdk2:Cyclin and the Cdk inhibitor p27Kip1 drives a switch-like entry into S phase. Furthermore, our model predicts that increasing Emi1 levels throughout S phase are critical in maintaining irreversibility of the G1/S transition, which we validate using Emi1 knockdown and live imaging of G1/S reporters. This work provides insight into the general design principles of the signaling networks governing the temporally abrupt transitions between cell-cycle phases. PMID:27136687

  9. Search for the 0- glueball in ϒ (1 S ) and ϒ (2 S ) decays

    NASA Astrophysics Data System (ADS)

    Jia, S.; Shen, C. P.; Yuan, C. Z.; Adachi, I.; Aihara, H.; Al Said, S.; Asner, D. M.; Aushev, T.; Ayad, R.; Babu, V.; Badhrees, I.; Bakich, A. M.; Bansal, V.; Barberio, E.; Behera, P.; Bhuyan, B.; Biswal, J.; Bonvicini, G.; Bozek, A.; Bračko, M.; Browder, T. E.; Červenkov, D.; Chang, P.; Chekelian, V.; Chen, A.; Cheon, B. G.; Chilikin, K.; Cho, K.; Choi, S.-K.; Choi, Y.; Cinabro, D.; Dash, N.; Di Carlo, S.; Doležal, Z.; Drásal, Z.; Dutta, D.; Eidelman, S.; Farhat, H.; Fast, J. E.; Ferber, T.; Fulsom, B. G.; Gaur, V.; Gabyshev, N.; Garmash, A.; Gillard, R.; Goldenzweig, P.; Golob, B.; Haba, J.; Hara, T.; Hayasaka, K.; Hayashii, H.; Hedges, M. T.; Hou, W.-S.; Iijima, T.; Inami, K.; Inguglia, G.; Ishikawa, A.; Itoh, R.; Jaegle, I.; Joffe, D.; Joo, K. K.; Julius, T.; Kang, K. H.; Katrenko, P.; Kawasaki, T.; Kichimi, H.; Kiesling, C.; Kim, D. Y.; Kim, H. J.; Kim, J. B.; Kim, K. T.; Kim, M. J.; Kim, S. H.; Kim, Y. J.; Kodyš, P.; Korpar, S.; Kotchetkov, D.; Križan, P.; Krokovny, P.; Kuhr, T.; Kulasiri, R.; Kuzmin, A.; Kwon, Y.-J.; Lange, J. S.; Li, C. H.; Li, L.; Li, Y.; Li Gioi, L.; Libby, J.; Liventsev, D.; Lubej, M.; Luo, T.; Masuda, M.; Matsuda, T.; Matvienko, D.; Miyabayashi, K.; Miyata, H.; Mizuk, R.; Moon, H. K.; Mori, T.; Nakao, M.; Nanut, T.; Nath, K. J.; Natkaniec, Z.; Nayak, M.; Niiyama, M.; Nisar, N. K.; Nishida, S.; Ogawa, S.; Okuno, S.; Ono, H.; Onuki, Y.; Ostrowicz, W.; Pakhlova, G.; Pal, B.; Park, C.-S.; Park, H.; Pestotnik, R.; Piilonen, L. E.; Pulvermacher, C.; Ritter, M.; Rostomyan, A.; Sakai, Y.; Sandilya, S.; Santelj, L.; Sanuki, T.; Savinov, V.; Schneider, O.; Schnell, G.; Schwanda, C.; Seino, Y.; Senyo, K.; Sevior, M. E.; Shebalin, V.; Shibata, T.-A.; Shiu, J.-G.; Shwartz, B.; Simon, F.; Sokolov, A.; Solovieva, E.; Starič, M.; Strube, J. F.; Sumihama, M.; Sumiyoshi, T.; Suzuki, K.; Takizawa, M.; Tamponi, U.; Tanida, K.; Tenchini, F.; Uchida, M.; Uglov, T.; Unno, Y.; Uno, S.; Urquijo, P.; Usov, Y.; Van Hulse, C.; Varner, G.; Vorobyev, V.; Wang, C. H.; Wang, M.-Z.; Wang, P.; Watanabe, Y.; Widmann, E.; Won, E.; Yamashita, Y.; Ye, H.; Yelton, J.; Zhang, Z. P.; Zhilich, V.; Zhukova, V.; Zhulanov, V.; Zupanc, A.; Belle Collaboration

    2017-01-01

    We report the first search for the JP C=0- glueball in ϒ (1 S ) and ϒ (2 S ) decays with data samples of (102 ±2 )×1 06 and (158 ±4 )×1 06 events, respectively, collected with the Belle detector. No significant signals are observed in any of the proposed production modes, and the 90% credibility level upper limits on their branching fractions in ϒ (1 S ) and ϒ (2 S ) decays are obtained. The inclusive branching fractions of the ϒ (1 S ) and ϒ (2 S ) decays into final states with a χc 1 are measured to be B (ϒ (1 S )→χc 1+anything)=(1.90 ±0.43 (stat )±0.14 (syst ))×10-4 with an improved precision over prior measurements and B (ϒ (2 S )→χc 1+anything)=(2.24 ±0.44 (stat )±0.20 (syst ))×10-4 for the first time.

  10. Molecular Characterization of the Llamas (Lama glama) Casein Cluster Genes Transcripts (CSN1S1, CSN2, CSN1S2, CSN3) and Regulatory Regions

    PubMed Central

    Pauciullo, Alfredo; Erhardt, Georg

    2015-01-01

    In the present paper, we report for the first time the characterization of llama (Lama glama) caseins at transcriptomic and genetic level. A total of 288 casein clones transcripts were analysed from two lactating llamas. The most represented mRNA populations were those correctly assembled (85.07%) and they encoded for mature proteins of 215, 217, 187 and 162 amino acids respectively for the CSN1S1, CSN2, CSN1S2 and CSN3 genes. The exonic subdivision evidenced a structure made of 21, 9, 17 and 6 exons for the αs1-, β-, αs2- and κ-casein genes respectively. Exon skipping and duplication events were evidenced. Two variants A and B were identified in the αs1-casein gene as result of the alternative out-splicing of the exon 18. An additional exon coding for a novel esapeptide was found to be cryptic in the κ-casein gene, whereas one extra exon was found in the αs2-casein gene by the comparison with the Camelus dromedaries sequence. A total of 28 putative phosphorylated motifs highlighted a complex heterogeneity and a potential variable degree of post-translational modifications. Ninety-six polymorphic sites were found through the comparison of the lama casein cDNAs with the homologous camel sequences, whereas the first description and characterization of the 5’- and 3’-regulatory regions allowed to identify the main putative consensus sequences involved in the casein genes expression, thus opening the way to new investigations -so far- never achieved in this species. PMID:25923814

  11. Molecular Characterization of the Llamas (Lama glama) Casein Cluster Genes Transcripts (CSN1S1, CSN2, CSN1S2, CSN3) and Regulatory Regions.

    PubMed

    Pauciullo, Alfredo; Erhardt, Georg

    2015-01-01

    In the present paper, we report for the first time the characterization of llama (Lama glama) caseins at transcriptomic and genetic level. A total of 288 casein clones transcripts were analysed from two lactating llamas. The most represented mRNA populations were those correctly assembled (85.07%) and they encoded for mature proteins of 215, 217, 187 and 162 amino acids respectively for the CSN1S1, CSN2, CSN1S2 and CSN3 genes. The exonic subdivision evidenced a structure made of 21, 9, 17 and 6 exons for the αs1-, β-, αs2- and κ-casein genes respectively. Exon skipping and duplication events were evidenced. Two variants A and B were identified in the αs1-casein gene as result of the alternative out-splicing of the exon 18. An additional exon coding for a novel esapeptide was found to be cryptic in the κ-casein gene, whereas one extra exon was found in the αs2-casein gene by the comparison with the Camelus dromedaries sequence. A total of 28 putative phosphorylated motifs highlighted a complex heterogeneity and a potential variable degree of post-translational modifications. Ninety-six polymorphic sites were found through the comparison of the lama casein cDNAs with the homologous camel sequences, whereas the first description and characterization of the 5'- and 3'-regulatory regions allowed to identify the main putative consensus sequences involved in the casein genes expression, thus opening the way to new investigations -so far- never achieved in this species.

  12. Parameterizing Stellar Spectra Using Deep Neural Networks

    NASA Astrophysics Data System (ADS)

    Li, Xiang-Ru; Pan, Ru-Yang; Duan, Fu-Qing

    2017-03-01

    Large-scale sky surveys are observing massive amounts of stellar spectra. The large number of stellar spectra makes it necessary to automatically parameterize spectral data, which in turn helps in statistically exploring properties related to the atmospheric parameters. This work focuses on designing an automatic scheme to estimate effective temperature ({T}{eff}), surface gravity ({log}g) and metallicity [Fe/H] from stellar spectra. A scheme based on three deep neural networks (DNNs) is proposed. This scheme consists of the following three procedures: first, the configuration of a DNN is initialized using a series of autoencoder neural networks; second, the DNN is fine-tuned using a gradient descent scheme; third, three atmospheric parameters {T}{eff}, {log}g and [Fe/H] are estimated using the computed DNNs. The constructed DNN is a neural network with six layers (one input layer, one output layer and four hidden layers), for which the number of nodes in the six layers are 3821, 1000, 500, 100, 30 and 1, respectively. This proposed scheme was tested on both real spectra and theoretical spectra from Kurucz’s new opacity distribution function models. Test errors are measured with mean absolute errors (MAEs). The errors on real spectra from the Sloan Digital Sky Survey (SDSS) are 0.1477, 0.0048 and 0.1129 dex for {log}g, {log}{T}{eff} and [Fe/H] (64.85 K for {T}{eff}), respectively. Regarding theoretical spectra from Kurucz’s new opacity distribution function models, the MAE of the test errors are 0.0182, 0.0011 and 0.0112 dex for {log}g, {log}{T}{eff} and [Fe/H] (14.90 K for {T}{eff}), respectively.

  13. Search for radiative decays of {upsilon}(1S) into {eta} and {eta}'

    SciTech Connect

    Athar, S. B.; Patel, R.; Potlia, V.; Stoeck, H.; Yelton, J.; Rubin, P.; Cawlfield, C.; Eisenstein, B. I.; Karliner, I.; Kim, D.; Lowrey, N.; Naik, P.; Sedlack, C.; Selen, M.; White, E. J.; Wiss, J.; Shepherd, M. R.; Besson, D.; Pedlar, T. K.; Cronin-Hennessy, D.

    2007-10-01

    We report on a search for the radiative decay of {upsilon}(1S) to the pseudoscalar mesons {eta} and {eta}{sup '} in (21.2{+-}0.2)x10{sup 6} {upsilon}(1S) decays collected with the CLEO III detector at the Cornell Electron Storage Ring. The {eta} meson was reconstructed in the three modes {eta}{yields}{gamma}{gamma}, {eta}{yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0}, or {eta}{yields}{pi}{sup 0}{pi}{sup 0}{pi}{sup 0}. The {eta}{sup '} meson was reconstructed in the mode {eta}{sup '}{yields}{pi}{sup +}{pi}{sup -}{eta} with {eta} decaying through any of the above three modes, and also {eta}{sup '}{yields}{gamma}{rho}{sup 0}, where {rho}{sup 0}{yields}{pi}{sup +}{pi}{sup -}. Five out of the seven submodes are found to have very low backgrounds. In four of them we find no signal candidates and in one [{upsilon}(1S){yields}{gamma}{eta}{sup '}, {eta}{sup '}{yields}{pi}{sup +}{pi}{sup -}{eta}, {eta}{yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0}] there are two good signal candidates, which is insufficient evidence to claim a signal. The other two submodes ({eta}{yields}{gamma}{gamma} and {eta}{sup '}{yields}{gamma}{rho}) are background limited, and show no excess of events in their signal regions. We combine the results from different channels and obtain upper limits at the 90% C.L. which are B({upsilon}(1S){yields}{gamma}{eta})<1.0x10{sup -6} and B({upsilon}(1S){yields}{gamma}{eta}{sup '})<1.9x10{sup -6}. Our limits are an order of magnitude tighter than the previous ones and below the predictions made by some theoretical models.

  14. The S1( 1A1)- S0( 1A1) Electronic Transition of Jet-Cooled o-Difluorobenzene

    NASA Astrophysics Data System (ADS)

    Swinn, Anna K.; Kable, Scott H.

    1998-09-01

    A detailed study of theS1(1A1)-S0(1A1) transition of jet-cooledo-difluorobenzene has been completed using the two techniques of laser-induced fluorescence excitation and dispersed, single vibronic level fluorescence spectroscopy. Analysis of over 60 dispersed fluorescence spectra resulted in both the assignment of 22 excited state vibrational frequencies and the confirmation of 23 ground state frequencies. The spectrum is dominated by Franck-Condon activity in totally symmetric vibrations with long progressions in the ring-breathing mode, ν9. By analogy with benzene and thepara- andmeta-substituted isomers, two vibronic coupling mechanisms are postulated to be responsible for the wealth of weaker symmetry-forbidden structure that has been observed. Single quantum changes inb2vibrations are postulated to appear due to first order vibronic coupling to a higher lyingB2electronic state. Combinations ofb1anda2modes are postulated to appear from second order vibronic coupling to anA1electronic state. This second order coupling causes a pronounced Duschinsky mixing among excited stateb1anda2modes with respect to their ground state counterparts. Franck-Condon factors are calculated for thea1progression-forming modes, anharmonic contributions are evaluated, one strong Fermi resonance is identified and analyzed, and the Duschinsky rotation matrix elements are evaluated for the most strongly affected modes, ν17and ν18. Several transitions in theoDFB-oDFB van der Waals dimer andoDFB-Ar complex are also assigned in the spectrum.

  15. Disk-Averaged Synthetic Spectra of Mars

    NASA Astrophysics Data System (ADS)

    Tinetti, Giovanna; Meadows, Victoria S.; Crisp, David; Fong ,William; Velusamy, Thangasamy; Snively, Heather

    2005-08-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin.

  16. H. N. Russell and Atomic Spectra

    NASA Astrophysics Data System (ADS)

    Devorkin, David

    2001-04-01

    “I would rather analyze spectra than do cross-word puzzles or do almost anything else” Henry Norris Russell wrote to William F. Meggers in 1927. Meggers, chief of the spectroscopy division at the NBS, had been surprised that an astrophysicist could be so keen about the analysis of complex spectra. But Russell was a new type of astrophysicist, one who made physics the core of his research. Spectra, for Russell, held the "master key" to knowledge about the universe, and of the atom. He was first attracted by the challenge of detecting and explaining anomalies, which he hoped would lead to new knowledge about the structure of matter. Then, influenced by physicists such as Meggers, he devoted himself to filling in the picture of the structure of atoms from their characteristic spectra as completely as possible. In this talk I will review how Russell worked with Meggers and became the nucleus of an ever-widening circle of spectroscopists devoted to the analysis of complex spectra.

  17. Improving Algorithm for Automatic Spectra Processing

    NASA Astrophysics Data System (ADS)

    Rackovic, K.; Nikolic, S.; Kotrc, P.

    2009-09-01

    Testing and improving of the computer program for automatic processing (flat-fielding) of a great number of solar spectra obtained with the horizontal heliospectrograph HSFA2 has been done. This program was developed in the Astronomical Institute of Academy of Sciences of the Czech Republic in Ondřejov. An irregularity in its work has been discovered, i.e. the program didn't work for some of the spectra. To discover a cause of this error an algorithm has been developed, and a program for examination of the parallelism of reference hairs crossing the spectral slit on records of solar spectra has been made. The standard methods for data processing have been applied-calculating and analyzing higher-order moments of distribution of radiation intensity. The spectra with the disturbed parallelism of the reference hairs have been eliminated from further processing. In order to improve this algorithm of smoothing of spectra, isolation and removal of the harmonic made by a sunspot with multiple elementary transformations of ordinates (Labrouste's transformations) are planned. This project was accomplished at the first summer astronomy practice of students of the Faculty of Mathematics, University of Belgrade, Serbia in 2007 in Ondřejov.

  18. Cloud supersaturations from CCN spectra Hoppel minima

    NASA Astrophysics Data System (ADS)

    Hudson, James G.; Noble, Stephen; Tabor, Samantha

    2015-04-01

    High-resolution cloud condensation nucleus (CCN) spectral measurements in two aircraft field projects, Marine Stratus/Stratocumulus Experiment (MASE) and Ice in Clouds Experiment-Tropical (ICE-T), often showed bimodality that had previously been observed in submicrometer aerosol size distributions obtained by differential mobility analyzers. However, a great deal of spectral shape variability from very bimodal to very monomodal was observed in close proximity. Cloud supersaturation (S) estimates based on critical S, Sc, at minimal CCN concentrations between two modes (Hoppel minima) were ascertained for 63% of 325 measured spectra. These cloud S were lower than effective S (Seff) determined by comparing ambient CCN spectra with nearby cloud droplet concentrations (Nc). Averages for the polluted MASE stratus were 0.15 and 0.23% and for the cumulus clouds of ICE-T 0.44 and 1.03%. This cloud S disagreement between the two methods might in part be due to the fact that Hoppel minima include the effects of cloud processing, which push CCN spectra toward lower S. Furthermore, there is less cloud processing by the smaller cloud droplets, which might be related to smaller droplets evaporating more readily. Significantly lower concentrations within the more bimodal spectra compared with the monomodal spectra indicated active physical processes: Brownian capture of interstitial CCN and droplet coalescence. Chemical cloud processing also contributed to bimodality, especially in MASE.

  19. Disk-averaged synthetic spectra of Mars

    NASA Technical Reports Server (NTRS)

    Tinetti, Giovanna; Meadows, Victoria S.; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather

    2005-01-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin.

  20. Disk-averaged synthetic spectra of Mars.

    PubMed

    Tinetti, Giovanna; Meadows, Victoria S; Crisp, David; Fong, William; Velusamy, Thangasamy; Snively, Heather

    2005-08-01

    The principal goal of the NASA Terrestrial Planet Finder (TPF) and European Space Agency's Darwin mission concepts is to directly detect and characterize extrasolar terrestrial (Earthsized) planets. This first generation of instruments is expected to provide disk-averaged spectra with modest spectral resolution and signal-to-noise. Here we use a spatially and spectrally resolved model of a Mars-like planet to study the detectability of a planet's surface and atmospheric properties from disk-averaged spectra. We explore the detectability as a function of spectral resolution and wavelength range, for both the proposed visible coronograph (TPFC) and mid-infrared interferometer (TPF-I/Darwin) architectures. At the core of our model is a spectrum-resolving (line-by-line) atmospheric/surface radiative transfer model. This model uses observational data as input to generate a database of spatially resolved synthetic spectra for a range of illumination conditions and viewing geometries. The model was validated against spectra recorded by the Mars Global Surveyor-Thermal Emission Spectrometer and the Mariner 9-Infrared Interferometer Spectrometer. Results presented here include disk-averaged synthetic spectra, light curves, and the spectral variability at visible and mid-infrared wavelengths for Mars as a function of viewing angle, illumination, and season. We also considered the differences in the spectral appearance of an increasingly ice-covered Mars, as a function of spectral resolution, signal-to-noise and integration time for both TPF-C and TPFI/ Darwin.

  1. EXPLORING THE MORPHOLOGY OF RAVE STELLAR SPECTRA

    SciTech Connect

    Matijevic, G.; Zwitter, T.; Bienayme, O.; Siebert, A.; Bland-Hawthorn, J.; Boeche, C.; Grebel, E. K.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Helmi, A.; Munari, U.; Navarro, J.; Parker, Q. A.; Reid, W.; Seabroke, G.; Siviero, A.; Steinmetz, M.; Williams, M.; Watson, F. G.; and others

    2012-06-01

    The RAdial Velocity Experiment (RAVE) is a medium-resolution (R {approx} 7500) spectroscopic survey of the Milky Way that has already obtained over half a million stellar spectra. They present a randomly selected magnitude-limited sample, so it is important to use a reliable and automated classification scheme that identifies normal single stars and discovers different types of peculiar stars. To this end, we present a morphological classification of {approx}350, 000 RAVE survey stellar spectra using locally linear embedding, a dimensionality reduction method that enables representing the complex spectral morphology in a low-dimensional projected space while still preserving the properties of the local neighborhoods of spectra. We find that the majority of all spectra in the database ({approx} 90%-95%) belong to normal single stars, but there is also a significant population of several types of peculiars. Among them, the most populated groups are those of various types of spectroscopic binary and chromospherically active stars. Both of them include several thousands of spectra. Particularly the latter group offers significant further investigation opportunities since activity of stars is a known proxy of stellar ages. Applying the same classification procedure to the sample of normal single stars alone shows that the shape of the projected manifold in two-dimensional space correlates with stellar temperature, surface gravity, and metallicity.

  2. Cleaning HI Spectra Contaminated by GPS RFI

    NASA Astrophysics Data System (ADS)

    Sylvia, Kamin; Hallenbeck, Gregory L.; Undergraduate ALFALFA Team

    2016-01-01

    The NUDET systems aboard GPS satellites utilize radio waves to communicate information regarding surface nuclear events. The system tests appear in spectra as RFI (radio frequency interference) at 1381MHz, which contaminates observations of extragalactic HI (atomic hydrogen) signals at 50-150 Mpc. Test durations last roughly 20-120 seconds and can occur upwards of 30 times during a single night of observing. The disruption essentially renders the corresponding HI spectra useless.We present a method that automatically removes RFI in HI spectra caused by these tests. By capitalizing on the GPS system's short test durations and predictable frequency appearance we are able to devise a method of identifying times containing compromised data records. By reevaluating the remaining data, we are able to recover clean spectra while sacrificing little in terms of sensitivity to extragalactic signals. This method has been tested on 500+ spectra taken by the Undergraduate ALFALFA Team (UAT), in which it successfully identified and removed all sources of GPS RFI. It will also be used to eliminate RFI in the upcoming Arecibo Pisces-Perseus Supercluster Survey (APPSS).This work has been supported by NSF grant AST-1211005.

  3. Background noise spectra of global seismic stations

    SciTech Connect

    Wada, M.M.; Claassen, J.P.

    1996-08-01

    Over an extended period of time station noise spectra were collected from various sources for use in estimating the detection and location performance of global networks of seismic stations. As the database of noise spectra enlarged and duplicate entries became available, an effort was mounted to more carefully select station noise spectra while discarding others. This report discusses the methodology and criteria by which the noise spectra were selected. It also identifies and illustrates the station noise spectra which survived the selection process and which currently contribute to the modeling efforts. The resulting catalog of noise statistics not only benefits those who model network performance but also those who wish to select stations on the basis of their noise level as may occur in designing networks or in selecting seismological data for analysis on the basis of station noise level. In view of the various ways by which station noise were estimated by the different contributors, it is advisable that future efforts which predict network performance have available station noise data and spectral estimation methods which are compatible with the statistics underlying seismic noise. This appropriately requires (1) averaging noise over seasonal and/or diurnal cycles, (2) averaging noise over time intervals comparable to those employed by actual detectors, and (3) using logarithmic measures of the noise.

  4. 76 FR 63316 - Prospective Grant of Exclusive License: Secreted Frizzled Related Protein-1 (sFRP-1) and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-12

    ... Prospective Grant of Exclusive License: Secreted Frizzled Related Protein-1 (sFRP-1) and derivatives thereof... a protein designated secreted Frizzled Related Protein-1 (sFRP-1). sFRP-1, also known as SARP-2 (Secreted Apoptosis Related Protein-2). The IP covers various sFRP-1 compositions and uses thereof....

  5. K-edge x-ray absorption spectra of Cs and Xe

    SciTech Connect

    Gomilsek, J. Padeznik; Kodre, A.; Arcon, I.; Hribar, M.

    2003-10-01

    X-ray absorption spectrum of cesium vapor in the K-edge region is measured in a stainless steel cell. The spectrum is free of the x-ray absorption fine structure signal and shows small features analogous to those in the spectrum of the neighbor noble gas Xe. Although the large natural width of the K vacancy (>10 eV) washes out most of the details, fingerprints of multielectron excitations can be recognized at energies close to Dirac-Fock estimates of doubly excited states 1s4(d,p,s) and 1s3(d,p). Among these, the 1s3p excitation 1000 eV above the K edge in both spectra is the deepest double excitation observed so far. Within the K-edge profile, some resolution is recovered with numerical deconvolution of the spectra, revealing the coexcitation of the 5(p,s) electrons, and even the valence 6s electron in Cs. As in homologue elements, three-electron excitations, either as separate channels or as configuration admixtures are required to explain some spectral features in detail.

  6. Bar Coding MS(2) Spectra for Metabolite Identification.

    PubMed

    Spalding, Jonathan L; Cho, Kevin; Mahieu, Nathaniel G; Nikolskiy, Igor; Llufrio, Elizabeth M; Johnson, Stephen L; Patti, Gary J

    2016-03-01

    Metabolite identifications are most frequently achieved in untargeted metabolomics by matching precursor mass and full, high-resolution MS(2) spectra to metabolite databases and standards. Here we considered an alternative approach for establishing metabolite identifications that does not rely on full, high-resolution MS(2) spectra. First, we select mass-to-charge regions containing the most informative metabolite fragments and designate them as bins. We then translate each metabolite fragmentation pattern into a binary code by assigning 1's to bins containing fragments and 0's to bins without fragments. With 20 bins, this binary-code system is capable of distinguishing 96% of the compounds in the METLIN MS(2) library. A major advantage of the approach is that it extends untargeted metabolomics to low-resolution triple quadrupole (QqQ) instruments, which are typically less expensive and more robust than other types of mass spectrometers. We demonstrate a method of acquiring MS(2) data in which the third quadrupole of a QqQ instrument cycles over 20 wide isolation windows (coinciding with the location and width of our bins) for each precursor mass selected by the first quadrupole. Operating the QqQ instrument in this mode yields diagnostic bar codes for each precursor mass that can be matched to the bar codes of metabolite standards. Furthermore, our data suggest that using low-resolution bar codes enables QqQ instruments to make MS(2)-based identifications in untargeted metabolomics with a specificity and sensitivity that is competitive to high-resolution time-of-flight technologies.

  7. Analysis of 1s(2s2p {sup 3}P)nl Rydberg states in the K-shell photoionization of the Be atom

    SciTech Connect

    Yoshida, Fumiko; Matsuoka, Leo; Takashima, Ryuta; Hasegawa, Shuichi; Nagata, Tetsuo; Azuma, Yoshiro; Obara, Satoshi; Koike, Fumihiro

    2006-06-15

    We have observed inner-shell photoionization of Be using synchrotron radiation in the energy region of the 1s(2s2p {sup 3}P)nl Rydberg states. We used a time-of-flight method to distinguish singly and doubly charged photoions and obtained the Be{sup +} [ns; n=5-12 ({sup 1}P)3s] and Be{sup 2+} [ns; n=5-8, nd=5,6 ({sup 1}P)3s] ion spectra with high resolution corresponding to an instrumental bandpass of 13 meV. Detailed analysis enabled the autoionization parameters, resonance energy position E{sub 0}, resonance width {gamma}, and Fano parameter q, to be obtained. From the resonance positions of the {sup 3}Pnl series members, the series limit was determined to be 127.97 eV, which is in good agreement with previous experiments.

  8. Red spectra from white and blue noise

    PubMed Central

    Balmforth, N. J.; Provenzale, A.; Spiegel, E. A.; Martens, M.; Tresser, C.; Wu, C. W.

    1999-01-01

    The value of maps of the interval in modelling population dynamics has recently been called into question because temporal variations from such maps have blue or white power spectra, whereas many observations of real populations show time-series with red spectra. One way to deal with this discrepancy is to introduce chaotic or stochastic fluctuations in the parameters of the map. This leads to on–off intermittency and can markedly redden the spectrum produced by a model that does not by itself have a red spectrum. The parameter fluctuations need not themselves have a red spectrum in order to achieve this effect. Because the power spectrum is not invariant under a change of variable, another way to redden the spectrum is by a suitable transformation of the variables used. The question this poses is whether spectra are the best means of characterizing a fluctuating variable.

  9. Crystal field spectra of lunar pyroxenes.

    NASA Technical Reports Server (NTRS)

    Burns, R. G.; Abu-Eid, R. M.; Huggins, F. E.

    1972-01-01

    Absorption spectra in the visible and near infrared regions have been obtained for pyroxene single crystals in rocks from the Apollo 11, 12, 14, and 15 missions. The polarized spectra are compared with those obtained from terrestrial calcic clinopyroxenes, subcalcic augites, pigeonites, and orthopyroxenes. The lunar pyroxenes contain several broad, intense absorption bands in the near infrared, the positions of which are related to bulk composition, Fe(2+) site occupancy and structure type of the pyroxene. The visible spectra contain several sharp, weak peaks mainly due to spin-forbidden transitions in Fe(2+). Additional weak bands in this region in Apollo 11 pyroxenes are attributed to Ti(3+) ions. Spectral features from Fe(3+), Mn(2+), Cr(3+), and Cr(2+) were not observed.

  10. Vibrational spectra of molecular fluids in nanopores

    NASA Astrophysics Data System (ADS)

    Arakcheev, V. G.; Morozov, V. B.

    2012-12-01

    Coherent anti-Stokes Raman spectroscopy (CARS) is applied for quantitative analysis of carbon dioxide phase composition in pores of nanoporous glass samples at nearcritical temperatures. Measurements of the 1388 1/cm Q-branch were made in a wide pressure range corresponding to coexistence of gas (gas-like), adsorbed and condensed phases within pores. At temperatures several degrees below the critical value, CARS spectra behavior is easy to interpret in terms of thermodynamic model of surface adsorption and capillary condensation. It allows estimating mass fractions of different phase components. Moreover, spectra measured at near critical temperatures 30.5 and 33°C have pronounced inhomogeneous shapes and indicate the presence of condensed phase in the volume of pores. The effect obviously reflects the fluid behaviour near the critical point in nanopores. Pores with smaller radii are filled with condensed phase at lower pressures. The analysis of the CARS spectra is informative for quantitative evaluation of phase composition in nanopores.

  11. Janus Spectra in Two-Dimensional Flows

    NASA Astrophysics Data System (ADS)

    Liu, Chien-Chia; Cerbus, Rory T.; Chakraborty, Pinaki

    2016-09-01

    In large-scale atmospheric flows, soap-film flows, and other two-dimensional flows, the exponent of the turbulent energy spectra, α , may theoretically take either of two distinct values, 3 or 5 /3 , but measurements downstream of obstacles have invariably revealed α =3 . Here we report experiments on soap-film flows where downstream of obstacles there exists a sizable interval in which α transitions from 3 to 5 /3 for the streamwise fluctuations but remains equal to 3 for the transverse fluctuations, as if two mutually independent turbulent fields of disparate dynamics were concurrently active within the flow. This species of turbulent energy spectra, which we term the Janus spectra, has never been observed or predicted theoretically. Our results may open up new vistas in the study of turbulence and geophysical flows.

  12. FAST INVERSION OF SOLAR Ca II SPECTRA

    SciTech Connect

    Beck, C.; Choudhary, D. P.; Rezaei, R.; Louis, R. E.

    2015-01-10

    We present a fast (<<1 s per profile) inversion code for solar Ca II lines. The code uses an archive of spectra that are synthesized prior to the inversion under the assumption of local thermodynamic equilibrium (LTE). We show that it can be successfully applied to spectrograph data or more sparsely sampled spectra from two-dimensional spectrometers. From a comparison to a non-LTE inversion of the same set of spectra, we derive a first-order non-LTE correction to the temperature stratifications derived in the LTE approach. The correction factor is close to unity up to log τ ∼ –3 and increases to values of 2.5 and 4 at log τ = –6 in the quiet Sun and the umbra, respectively.

  13. Molecular dynamics and spectra. II. Diatomic Raman

    NASA Astrophysics Data System (ADS)

    Berens, Peter H.; White, Steven R.; Wilson, Kent R.

    1981-07-01

    This paper and paper I in this series [P.H. Berens and K.R. Wilison, J. Chem. Phys. 74, 4872 (1981)] indicate that infrared and Raman rotational and fundamental vibrational-rotational spectra of dense systems (high pressure gases, liquids, and solids) are essentially classical, in that they can be computed and understood from a basically classical mechanical viewpoint, with some caveats for features in which anharmonicity is important, such as the detailed shape of Q branches. It is demonstrated here, using the diatomic case as an example, that ordinary, i.e., nonresonant, Raman band contours can be computed from classical mechanics plus simple quantum corrections. Classical versions of molecular dynamics, linear response theory, and ensemble averaging, followed by straightforward quantum corrections, are used to compute the pure rotational and fundamental vibration-rotational Raman band contours of N2 for the gas phase and for solutions of N2 in different densities of gas phase Ar and in liquid Ar. The evolution is seen from multiple peaked line shapes characteristic of free rotation in the gas phase to single peaks characteristic of hindered rotation in the liquid phase. Comparison is made with quantum and correspondence principle classical gas phase spectral calculations and with experimental measurements for pure N2 and N2 in liquid Ar. Three advantages are pointed out for a classical approach to infrared and Raman spectra. First, a classical approach can be used to compute the spectra of complex molecular systems, e.g., of large molecules, clusters, liquids, solutions, and solids. Second, this classical approach can be extended to compute the spectra of nonequilibrium and time-dependent systems, e.g., infrared and Raman spectra during the course of chemical reactions. Third, a classical viewpoint allows experimental infrared and Raman spectra to be understood and interpreted in terms of atomic motions with the considerable aid of classical models and of our

  14. Infrared spectra of cesium chloride aqueous solutions

    NASA Astrophysics Data System (ADS)

    Max, Jean-Joseph; Chapados, Camille

    2000-10-01

    The aqueous solutions of CsCl were studied at room temperature by infrared (IR) spectroscopy in the entire solubility range, 0-1200 g/L, using attenuated total reflection (ATR) sampling. The influence of anomalous dispersion on the IR-ATR spectra was evaluated by calculating the imaginary refractive index, k(ν), of each sample. Factor analysis (FA) was used to determine the number and abundance of species in the solutions. FA applied to both k(ν) spectra and IR-ATR spectra produced two principal spectra with a similar abundance of species. This result indicates that, even at high salt concentration, the optical effects do not influence the chemical analysis of IR-ATR spectra. The spectral modifications related to the salt concentrations are mainly first order. Second order effects were observed, but being weak, were not investigated. The two principal spectra are related to the two species present in the solution: pure water and CsCl-solvated water. From the latter, 2.8±0.4 water molecules were calculated to be associated with each close-bound Cs+/Cl- ion pair. In the case of KCl and NaCl aqueous solutions, both of which showed the same number of species, the number of water molecules associated to an ion pair was 5.0±0.4. That the latter number is different from that of CsCl indicates that the interaction between water molecules and ion pairs is different when cation Na or K in the chloride salt is replaced by Cs.

  15. Observed and theoretical spectra in the 10-100 A interval. [of solar spectra

    NASA Technical Reports Server (NTRS)

    Brown, W. A.; Bruner, M. E.; Acton, L. W.

    1988-01-01

    The soft X-ray spectra recorded in two sounding-rocket flights in 1982 and 1985 are compared with predicted spectra. The processed densitometer trace of the full spectrum is presented, together with the new spectrum from the 1985 experiment. The intensities of the lines are then compared with predictions.

  16. Experimental Constraints on Neutrino Spectra Following Fission

    NASA Astrophysics Data System (ADS)

    Napolitano, Jim; Daya Bay Collaboration

    2016-09-01

    We discuss new initiatives to constrain predictions of fission neutrino spectra from nuclear reactors. These predictions are germane to the understanding of reactor flux anomalies; are needed to reduce systematic uncertainty in neutrino oscillation spectra; and inform searches for the diffuse supernova neutrino background. The initiatives include a search for very high- Q beta decay components to the neutrino spectrum from the Daya Bay power plant; plans for a measurement of the β- spectrum from 252Cf fission products; and precision measurements of the 235U fission neutrino spectrum from PROSPECT and other very short baseline reactor experiments.

  17. A data base of geologic field spectra

    NASA Technical Reports Server (NTRS)

    Kahle, A. B.; Goetz, A. F. H.; Paley, H. N.; Alley, R. E.; Abbott, E. A.

    1981-01-01

    It is noted that field samples measured in the laboratory do not always present an accurate picture of the ground surface sensed by airborne or spaceborne instruments because of the heterogeneous nature of most surfaces and because samples are disturbed and surface characteristics changed by collection and handling. The development of new remote sensing instruments relies on the analysis of surface materials in their natural state. The existence of thousands of Portable Field Reflectance Spectrometer (PFRS) spectra has necessitated a single, all-inclusive data base that permits greatly simplified searching and sorting procedures and facilitates further statistical analyses. The data base developed at JPL for cataloging geologic field spectra is discussed.

  18. Separating Peaks in X-Ray Spectra

    NASA Technical Reports Server (NTRS)

    Nicolas, David; Taylor, Clayborne; Wade, Thomas

    1987-01-01

    Deconvolution algorithm assists in analysis of x-ray spectra from scanning electron microscopes, electron microprobe analyzers, x-ray fluorescence spectrometers, and like. New algorithm automatically deconvolves x-ray spectrum, identifies locations of spectral peaks, and selects chemical elements most likely producing peaks. Technique based on similarities between zero- and second-order terms of Taylor-series expansions of Gaussian distribution and of damped sinusoid. Principal advantage of algorithm: no requirement to adjust weighting factors or other parameters when analyzing general x-ray spectra.

  19. Vibrational spectra study on quinolones antibiotics

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Yu, Ke; Wang, Sihuan

    2006-09-01

    In order to be able to fully understand and easily identify the quilonoles, we collected IR and Raman spectra of six quinolones, and attempted to assign the attribution of the observed frequencies and their association with specific modes of vibration. According to the structure, the compounds were divided into the groups, and the similarities and differences were further studied by comparing. The result of the study shows that the frequency and intensity are comparable to the corresponding structure. The spectra not only have the commonness but also the individualities.

  20. Hadron rapidity spectra within a hybrid model

    NASA Astrophysics Data System (ADS)

    Khvorostukhin, A. S.; Toneev, V. D.

    2017-01-01

    A 2-stage hybrid model is proposed that joins the fast initial state of interaction, described by the hadron string dynamics (HSD) model, to subsequent evolution of the expanding system at the second stage, treated within ideal hydrodynamics. The developed hybrid model is assigned to describe heavy-ion collisions in the energy range of the NICA collider under construction in Dubna. Generally, the model is in reasonable agreement with the available data on proton rapidity spectra. However, reproducing proton rapidity spectra, our hybrid model cannot describe the rapidity distributions of pions. The model should be improved by taking into consideration viscosity effects at the hydrodynamical stage of system evolution.