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Sample records for kev fullerene bombardment

  1. The production and sputtering of S2 by keV ion bombardment

    NASA Technical Reports Server (NTRS)

    Boring, J. W.; Chrisey, D. B.; Oshaughnessy, D. J.; Phipps, J. A.; Zhao, N.

    1986-01-01

    The ion bombardment of S-containing molecules in comets is simulated experimentally. Mass-analyzed 30-keV beams of Ar(+) and He(+) are directed at solid S, H2S, and CS2 targets at temperatures 15 K, and the neutral molecular species produced are ionized and analyzed using a quadrupole mass spectrometer. The dominant species detected are S1 and S2 for the S target, H2S and S2 for the H2S target, and S, CS, S2, and CS2 for the CS2 target. In the latter case, it is found that after about 10 to the 14th He(+) ions/sq cm have struck the target, further sputtering is prevented by formation of a dark brown deposit which is stable at room temperature; the residue forms more slowly when Ar(+) ions are used. These results, indicating relatively efficient S2 production by ion bombardment, are applied to theoretical models of S2 production and/or ejection by solar-wind, solar-flare, or cosmic-ray ions striking comets. It is found that direct solar-wind production of S2 by sputtering is unlikely at realistic bombardment rates, but that H2S-S2 conversion by energetic ions could be significant, with less stringent ice-temperature and irradiation-flux constraints than in the case of S2 production by photons.

  2. Study of the surface activation of ETFE by low energy (keV) Si and N bombardment

    NASA Astrophysics Data System (ADS)

    Parada, M. A.; de Almeida, A.; Muntele, C.; Muntele, I.; Delalez, N.; Ila, D.

    2005-12-01

    The ethylenetetrafluoroethylene (ETFE) is a polymer formed by alternating ethylene and tetrafluoroethylene segments. It can be applied in the field of medical physics as intra venous catheters and as radiation dosimeters. The increasing application of polymeric materials in technological and scientific fields has motivated the use of surface treatments to modify the physical and chemical properties of polymer surfaces. When a material is exposed to ionizing radiation, it suffers damage leading to surface activation depending on the type, energy and intensity of the applied radiation. In order to determine the radiation damage and the surface activation mechanism ETFE films were bombarded with keV Si and N at various fluences. The bombarded film was also analyzed with optical absorption photospectrometry (OAP), Raman and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy showing quantitatively the chemical nature at the damage caused by the Si and N bombardment.

  3. Stability of Extraterrestrial Glycine under Energetic Particle Radiation Estimated from 2 keV Electron Bombardment Experiments

    NASA Astrophysics Data System (ADS)

    Mat, B.; Tanarro, I.; Escribano, R.; Moreno, M. A.; Herrero, V. J.

    2015-06-01

    The destruction of solid glycine under irradiation with 2 keV electrons has been investigated by means of IR spectroscopy. Destruction cross sections, radiolysis yields, and half-life doses were determined for samples at 20, 40, 90, and 300 K. The thickness of the irradiated samples was kept below the estimated penetration depth of the electrons. No significant differences were obtained in the experiments below 90 K, but the destruction cross section at 300 K was larger by a factor of 2. The radiolysis yields and half-life doses are in good accordance with recent MeV proton experiments, which confirms that electrons in the keV range can be used to simulate the effects of cosmic rays if the whole sample is effectively irradiated. In the low temperature experiments, electron irradiation leads to the formation of residues. IR absorptions of these residues are assigned to the presence CO2, CO, OCN-, and CN- and possibly to amide bands I to III. The protection of glycine by water ice is also studied. A water ice film of 150 nm is found to provide efficient shielding against the bombardment of 2 keV electrons. The results of this study show also that current Monte Carlo predictions provide a good global description of electron penetration depths. The lifetimes estimated in this work for various environments ranging from the diffuse interstellar medium to the inner solar system, show that the survival of hypothetical primeval glycine from the solar nebula in present solar system bodies is not very likely.

  4. Effect of 100 keV helium ion bombardment on surface topography and microstructure of Ni 33Zr 67 glass

    NASA Astrophysics Data System (ADS)

    Tyagi, A. K.; Nandedkar, R. V.; Krishan, K.

    1983-02-01

    The surface damage of Ni 33Zr 67 glass irradiated with 100 keV helium ions at room temperature has been investigated using scanning electron microscopy. The critical dose for blister formation was found to be 1 10 18ions/ cm2. Two generations of blisters and their exfoliations were observed. Alignment of first-generation exfoliated blister craters parallel to the ribbon length and rupture of second-generation blisters into a regular four-petalled configuration were rather striking observations. Flaking was observed only in the case of high dose-rate bombardment. The skin thicknesses of blisters in each of the two generations and that of the exfoliated layer in the case of flaking were nearly equal and compare well with the calculated mean projected range of helium ions in this alloy. Irradiation-induced partial crystallization of the Ni 33Zr 67 glass was observed by means of transmission electron microscopy but small helium bubbles could be resolved only at high ion fluences.

  5. Secondary ion emission from polymethacrylate LB-layers under 0.5 11 keV atomic and molecular primary ion bombardment

    NASA Astrophysics Data System (ADS)

    Stapel, D.; Thiemann, M.; Benninghoven, A.

    2000-02-01

    Secondary ion yields Y(X iq) increase considerably when changing from atomic to molecular primary ions, whereas the parallel increase in the corresponding damage cross sections ?(X iq) is much smaller. This results in a net increase of ion formation efficiencies E(X iq)= Y/ ?. For a more detailed understanding of the complex sputtering and ion formation processes, in particular for molecular primary ion bombardment, the secondary ion emission of well-defined polymethacrylate LB mono- and multilayers on Ag was investigated. For characteristic secondary ions X iq emitted from these overlayers Y(X iq) and ?(X iq) for 11 keV Ne +, Ar +, Xe +, O 2+, SF 5+, C 7H 7+, C 10H 8+, C 6F 6+ and C 10F 8+ bombardment were determined and compared. The influence of primary ion energy was investigated in the energy range between 0.5 and 10 keV for Xe + and SF 5+ bombardment. For multilayers we found yield increases up to nearly a factor of 1000, when changing from Ne + to SF 5+ bombardment. We found a more pronounced yield and efficiency enhancement for multi than for monolayer coverages, a saturation of Y, ? and E enhancement for primary ions made of more than 6 heavy constituents at constant primary ion energy, no chemical effect on the secondary ion yields under static SIMS conditions (SF 5+ / C 7H 7+ e.g.), and a pronounced decrease in secondary ion yields and secondary ion formation efficiencies for SF 5+ primary ions with impact energies below 2 keV.

  6. Steady State Sputtering Yields and Surface Compositions of Depleted Uranium and Uranium Carbide bombarded by 30 keV Gallium or 16 keV Cesium Ions.

    SciTech Connect

    Siekhaus, W. J.; Teslich, N. E.; Weber, P. K.

    2014-10-23

    Depleted uranium that included carbide inclusions was sputtered with 30-keV gallium ions or 16-kev cesium ions to depths much greater than the ions’ range, i.e. using steady-state sputtering. The recession of both the uranium’s and uranium carbide’s surfaces and the ion corresponding fluences were used to determine the steady-state target sputtering yields of both uranium and uranium carbide, i.e. 6.3 atoms of uranium and 2.4 units of uranium carbide eroded per gallium ion, and 9.9 uranium atoms and 3.65 units of uranium carbide eroded by cesium ions. The steady state surface composition resulting from the simultaneous gallium or cesium implantation and sputter-erosion of uranium and uranium carbide were calculated to be U₈₆Ga₁₄, (UC)₇₀Ga₃₀ and U₈₁Cs₉, (UC)₇₉Cs₂₁, respectively.

  7. Spectral reflectance change and luminescence of selected salts during 2-10 KeV proton bombardment - Implications for Io

    NASA Technical Reports Server (NTRS)

    Nelson, R. M.; Nash, D. B.

    1979-01-01

    Radiation damage and luminescence caused by magnetospheric charged particles have been suggested by several investigators as mechanisms that are capable of explaining some of the peculiar spectral/albedo features of Io. In the present paper, this possibility is pursued by measuring the UV-visual spectral reflectance and luminescent efficiency of several proposed Io surface constituents during 2 to 10 keV proton irradiation at room and low temperatures. The luminescence efficiencies of pure samples, studied in the laboratory, suggest that charged-particle induced luminescence from Io's surface might be observable by spacecraft such as Voyager when viewing Io's dark side.

  8. Sputtering yields, range and range straggling in Al following Kr + ions bombardment in the energy range (20-160) keV

    NASA Astrophysics Data System (ADS)

    Mammeri, S.; Ouichaoui, S.; Zemih, R.; Ammi, H.; Abdesselam, M.; Chami, A. C.

    2005-10-01

    The sputtering of Al metallic films by 84Kr+ ions has been studied over the energy range (20-160) keV. Sputtering yield data have been extracted by means of the Rutherford backscattering technique (RBS) using a 2 MeV beam of 4He+ ions. They have been compared to values derived by Sigmund's linear cascade theory, Yamamura's semi-empirical formula or by Monte Carlo computer simulation using the TRIM code. A fair agreement was observed between the measured sputtering yields and the predicted ones. The depth profiles of the implanted Kr+ ions into Al have also been measured, and then fitted assuming Gaussian shape distributions, which allowed us to extract the projected range, Rp, and the associated range straggling, ΔRp. For the former stopping parameter, a very good agreement is obtained between experiment and the LSS theory predictions while the MC simulation also accounts satisfactorily for the measured data over the whole explored energy range, reflecting an adequate description of the projectile-target interaction by the universal potential of the Thomas-Fermi type assumed in the LSS formalism. In contrast, the ΔRp measured data show to be consistent with the predicted values only at E ⩾ 60 keV but lie to ∼30% above them at lower energies. This discrepancy not caused by the sputtering effect relates to an incomplete evaluation of the range straggling by theory at low bombarding energies.

  9. The temperature effect on the glycine decomposition induced by 2 keV electron bombardment in space analog conditions

    NASA Astrophysics Data System (ADS)

    Pilling, Sergio; Nair, Binu G.; Escobar, Antonio; Fraser, Helen; Mason, Nigel

    2014-03-01

    Glycine is the simplest proteinaceous amino acid that has been extensively detected in carbonaceous meteorites and was recently observed in the cometary samples returned to Earth by NASA's Stardust spacecraft. In space, such species is exposed to several radiation fields at different temperatures. In aqueous solutions, this species appears mainly as zwitterionic glycine (+NH3CH2COO-) however, in solid phase, it may be found in amorphous or crystalline forms. Here, we present an experimental study on the destruction of two zwitterionic glycine crystals ( ?- and ?-form) at two different temperatures (300 K and 14 K) by 2 keV electrons in an attempt to test the behavior and stability of this molecular species in different space environments. The samples were analyzed in situ by Fourier transform infrared spectrometry at electron fluences. The experiments were carried out under ultra-high vacuum conditions at the Molecular Physics Laboratory at the Open University at Milton Keynes, UK. The dissociation cross section of glycine is approximately 5 times higher for the 14 K samples when compared to the 300 K samples. In contrast, no significant differences emerged between the dissociation cross sections of ?- and ?-forms of glycine for fixed temperature experiments. We therefore conclude that the destruction cross section is more heavily dependent on temperature than the phase of the condensed glycine material. This may be associated with the opening of additional reaction routes in the frozen samples involving the trapped daughter species (e.g. CO2 and CO). The half-life of studied samples extrapolated to space conditions shows that glycine molecules on the surface of interstellar grains has less survivability and they are highly sensitive to ambient radiations, however, they can survive extended period of time in the solar system like environments. Survivability increases by a factor of 5 if the samples are at 300 K when compared to low temperature experiments at 14 K and is independent of the crystalline structure. In addition, this survival would increase if the molecular species were protected by several layers of other molecular species as trapped in comet mantles or embedded within regolith in asteroids/lunar surfaces. The understanding of the excitation and dissociation processes of organic compounds in space simulation is highly required to put constrains in the puzzle over the origin of life in the primitive Earth.

  10. Single impacts of keV fullerene ions on free standing graphene: Emission of ions and electrons from confined volume

    NASA Astrophysics Data System (ADS)

    Verkhoturov, Stanislav V.; Geng, Sheng; Czerwinski, Bartlomiej; Young, Amanda E.; Delcorte, Arnaud; Schweikert, Emile A.

    2015-10-01

    We present the first data from individual C60 impacting one to four layer graphene at 25 and 50 keV. Negative secondary ions and electrons emitted in transmission were recorded separately from each impact. The yields for Cn- clusters are above 10% for n ? 4, they oscillate with electron affinities and decrease exponentially with n. The result can be explained with the aid of MD simulation as a post-collision process where sufficient vibrational energy is accumulated around the rim of the impact hole for sputtering of carbon clusters. The ionization probability can be estimated by comparing experimental yields of Cn- with those of Cn0 from MD simulation, where it increases exponentially with n. The ionization probability can be approximated with ejecta from a thermally excited (3700 K) rim damped by cluster fragmentation and electron detachment. The experimental electron probability distributions are Poisson-like. On average, three electrons of thermal energies are emitted per impact. The thermal excitation model invoked for Cn- emission can also explain the emission of electrons. The interaction of C60 with graphene is fundamentally different from impacts on 3D targets. A key characteristic is the high degree of ionization of the ejecta.

  11. Medium-energy ion irradiation of Si and Ge wafers: studies of surface nanopatterning and signature of recrystallization in 100 keV Kr+ bombarded a-Si

    NASA Astrophysics Data System (ADS)

    Kumar, Pravin

    2016-03-01

    We report new and exciting experimental results on ion-induced nanopatterning of a-Si and a-Ge surfaces. The crystalline Si (100) and Ge (100) wafers were amorphized and an a/c interface was developed by pre-irradiation with a 50 keV Ar+ beam at normal incidence with an ion fluence of 5.0 × 1015 ions cm‑2. These amorphized surfaces were post-irradiated with Ar+ and Kr+ beams at an angle of 60°. The post irradiation was done with ion fluences of 1.0 × 1017 ions cm‑2. For each beam, two energies (50 and 200 keV for Ar+, 100 and 250 keV for Kr+) were chosen to ensure ion stopping in both sides of the a/c interface. Regular nanopatterning (in the form of ripples) is observed on the Ge surface only with the post irradiation of the Kr+ beam. The Si surface showed regular nanopatterning with the irradiation of both beams with two energies. For the ion beams crossing the a/c interface, ripples of higher amplitude and longer wavelength were formed. Further, the irradiation with a heavy beam yielded surface ripples of relatively larger amplitudes. The Raman measurements confirm amorphization of the pre-irradiated surfaces. Surprisingly, the post-irradiated Si surface with the 100 keV Kr+ beam showed evidence of recrystallization. In the paper we discuss the physics at the interface and explain the experimental findings.

  12. Fullerene Machines

    NASA Technical Reports Server (NTRS)

    Globus, Al; Saini, Subhash

    1998-01-01

    Recent computational efforts at NASA Ames Research Center and computation and experiment elsewhere suggest that a nanotechnology of machine phase functionalized fullerenes may be synthetically accessible and of great interest. We have computationally demonstrated that molecular gears fashioned from (14,0) single-walled carbon nanotubes and benzyne teeth should operate well at 50-100 gigahertz. Preliminary results suggest that these gears can be cooled by a helium atmosphere and a laser motor can power fullerene gears if a positive and negative charge have been added to form a dipole. In addition, we have unproven concepts based on experimental and computational evidence for support structures, computer control, a system architecture, a variety of components, and manufacture. Combining fullerene machines with the remarkable mechanical properties of carbon nanotubes, there is some reason to believe that a focused effort to develop fullerene nanotechnology could yield materials with tremendous properties.

  13. Fullerene materials

    SciTech Connect

    Malhotra, R.; Ruoff, R.S.; Lorents, D.C.

    1995-04-01

    Fullerenes are all-carbon cage molecules. The most celebrated fullerene is the soccer-ball shaped C{sub 60}, which is composed of twenty hexagons and twelve pentagons. Because its structure is reminiscent of the geodesic domes of architect R. Buckminster Fuller, C{sub 60} is called buckminsterfullerene, and all the materials in the family are designated fullerenes. Huffman and Kraetschmer`s discovery unleashed activity around the world as scientists explored production methods, properties, and potential uses of fullerenes. Within a short period, methods for their production in electric arcs, plasmas, and flames were discovered, and several companies began selling fullerenes to the research market. What is remarkable is that in all these methods, carbon atoms assemble themselves into cage structures. The capability for self-assembly points to some inherent stability of these structures that allows their formation. The unusual structure naturally leads to unusual properties. Among them are ready solubility in solvents and a relatively high vapor pressure for a pure carbon material. The young fullerene field has already produced a surprising array of structures for the development of carbon-base materials having completely new and different properties from any that were previously possible.

  14. Fullerene Machines

    NASA Technical Reports Server (NTRS)

    Globus, Al; Saini, Subhash (Technical Monitor)

    1998-01-01

    Fullerenes possess remarkable properties and many investigators have examined the mechanical, electronic and other characteristics of carbon SP2 systems in some detail. In addition, C-60 can be functionalized with many classes of molecular fragments and we may expect the caps of carbon nanotubes to have a similar chemistry. Finally, carbon nanotubes have been attached to t he end of scanning probe microscope (Spill) tips. Spills can be manipulated with sub-angstrom accuracy. Together, these investigations suggest that complex molecular machines made of fullerenes may someday be created and manipulated with very high accuracy. We have studied some such systems computationally (primarily functionalized carbon nanotube gears and computer components). If such machines can be combined appropriately, a class of materials may be created that can sense their environment, calculate a response, and act. The implications of such hypothetical materials are substantial.

  15. Switching Molecular Orientation of Individual Fullerene at Room Temperature

    PubMed Central

    Liu, Lacheng; Liu, Shuyi; Chen, Xiu; Li, Chao; Ling, Jie; Liu, Xiaoqing; Cai, Yingxiang; Wang, Li

    2013-01-01

    Reversible molecular switches with molecular orientation as the information carrier have been achieved on individual fullerene molecules adsorbed on Si (111) surface at room temperature. Scanning tunneling microscopy imaging directly demonstrates that the orientation of individual fullerene with an adsorption geometry of 5-6 bond is rotated by integral times as 30 degree after a pulse bias is applied between the STM tip and the molecule. Dependences of the molecular rotation probability on the voltage and the process of applied bias reveal that the rotation of a fullerene molecule takes place in two successive steps: the bonding between the fullerene and the Si surface is firstly weakened via electronic excitation and then low energy electron bombardment causes the molecule to rotate by certain degree. PMID:24162548

  16. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M. (1324 59th St., Downers Grove, IL 60515)

    1993-01-01

    A method of forming synthetic diamond on a substrate is disclosed. The method involves providing a substrate surface covered with a fullerene or diamond coating, positioning a fullerene in an ionization source, creating a fullerene vapor, ionizing fullerene molecules, accelerating the fullerene ions to energies above 250 eV to form a fullerene ion beam, impinging the fullerene ion beam on the substrate surface and continuing these steps to obtain a diamond thickness on the substrate.

  17. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M. (1324 59th St., Downers Grove, IL 60515)

    1994-01-01

    A method of forming synthetic diamond on a substrate. The method involves providing a substrate surface covered with a fullerene or diamond coating, positioning a fullerene in an ionization source, creating a fullerene vapor, ionizing fullerene molecules, accelerating the fullerene ions to energies above 250 eV to form a fullerene ion beam, impinging the fullerene ion beam on the substrate surface and continuing these steps to obtain a diamond film thickness on the substrate.

  18. Fullerene nanowhiskers and related fullerene nanomaterials

    NASA Astrophysics Data System (ADS)

    Miyazawa, K.; Kato, R.; Saito, K.; Kizuka, T.; Mashino, T.; Nakamura, S.

    2009-04-01

    Since the discovery of C60 nanowhiskers in a colloidal solution of PZT in 2001, various low-dimensional fullerene nanomaterials such as fullerene nanotubes and fullerene nanosheets have been synthesized by the liquid-liquid interfacial precipitation method (LLIP method) as well as the C60 and C70 nanowhiskers. The LLIP method is an excellent process to synthesize the quasi one-dimensional fullerene nanomaterials. This paper first reviews the typical fullerene nano and micro materials that have been prepared by the LLIP method and then show that the LLIP method is also applicable to the synthesis of composite C60 nano and micro whiskers containing wide compositions of C60 derivative molecules.

  19. Fullerene Nanogears

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Numerical Aerospace Simulation Systems Division (NAS) of the NASA Ames Research Center, Moffett Field, California is conducting research into molecular-sized devices known as Nanotechnology. This photograph depicts two 'Fullerene Nano-gears' with multiple teeth. The hope is that one day, products can be constructed made of thousands of tiny machines that could self-repair and adapt to the environment in which they exist. Researchers have simulated attaching benzyne molecules to the outside of a nanotube to form gear teeth. Nanotubes are molecular-sized pipes made of carbon atoms. To 'drive' the gears, the supercomputer simulated a laser that served as a motor. The laser creates an electric field around the nanotube. A positively charged atom is placed on one side of the nanotube, and a negatively charged atom on the other side. The electric field drags the nanotube around like a shaft turning. Jie Han, Al Globus, Richard Jaffe and Glenn Deardorff are the authors of a technical paper detailing this technology which appears in The Journal of Nanotechnology.

  20. [Fullerenes in biology].

    PubMed

    Krokosz, Anita

    2007-01-01

    Fullerenes are chemical structures made of carbon atoms. The stable form is molecule composed of 60 carbon atoms arranged in a soccer ball-shaped structure. With respect to its electron donor and acceptor capability and photochemical behavior fullerenes can be effective antioxidants and radical scavengers or prooxidants and photosensitizers. These properties of fullerenes have paid attention on their possible biological applications. Results of previous studies point to the great dependance of fullerenes activity upon quality, quantity and geometry of substituents in fullerene derivatives. Some of fullerene derivatives show antiviral and antimicrobial activity, including anti-HIV properties. C60 and its derivatives are able to exhibit cytotoxic and enzyme-inhibiting abilities as well as radical-quenching and antioxidative abilities. Generation of reactive oxygen species under influence of visible light is another ability of fullerene derivetives desired in photodynamic therapy. PMID:17718393

  1. Fullerenes in Allende Meteorite

    NASA Technical Reports Server (NTRS)

    Becker, L.; Bada, J. L.; Winans, R. E.; Bunch, T. E.

    1994-01-01

    The detection of fullerenes in deposits from meteor impacts has led to renewed interest in the possibility that fullerenes are present in meteorites. Although fullerenes have not previously been detected in the Murchison and Allende meteorites, the Allende meteorite is known to contain several well-ordered graphite particles which are remarkably similar in size and appearance to the fullerene-related structures carbon onions and nanotubes. We report that fullerenes are in fact present in trace amounts in the Allende meteorite. In addition to fullerenes, we detected many polycyclic aromatic hydrocarbons (PAHs) in the Allende meteorite, consistent with previous reports. In particular, we detected benzofluoranthene and corannulene (C20H10), five-membered ring structures which have been proposed as precursors to the formation of fullerene synthesis, perhaps within circumstellar envelopes or other sites in the interstellar medium.

  2. Depth resolution improvement in secondary ion mass spectrometry analysis using metal cluster complex ion bombardment

    NASA Astrophysics Data System (ADS)

    Tomita, M.; Kinno, T.; Koike, M.; Tanaka, H.; Takeno, S.; Fujiwara, Y.; Kondou, K.; Teranishi, Y.; Nonaka, H.; Fujimoto, T.; Kurokawa, A.; Ichimura, S.

    2006-07-01

    Secondary ion mass spectrometry analyses were carried out using a metal cluster complex ion of Ir4(CO)7+ as a primary ion beam. Depth resolution was evaluated as a function of primary ion species, energy, and incident angle. The depth resolution obtained using cluster ion bombardment was considerably better than that obtained by oxygen ion bombardment under the same experimental condition due to reduction of atomic mixing in the depth. The authors obtained a depth resolution of 1nm under 5keV, 45 condition. Depth resolution was degraded by ion-bombardment-induced surface roughness at 5keV with higher incident angles.

  3. Combustion method for producing fullerenes

    DOEpatents

    Howard, Jack B.; McKinnon, J. Thomas

    1993-01-01

    A method for synthesizing fullerenes in flames is provided. Fullerenes are prepared by burning carbon-containing compounds in a flame and collecting the condensibles. The condensibles contain the desired fullerenes. Fullerene yields can be optimized and fullerene composition can be selectively varied. Fullerene yields and compositions are determined by selectively controlling flame conditions and parameters such as C/O ratio, pressure, temperature, residence time, diluent concentration and gas velocity.

  4. Combustion method for producing fullerenes

    DOEpatents

    Howard, J.B.; McKinnon, J.T.

    1993-12-28

    A method for synthesizing fullerenes in flames is provided. Fullerenes are prepared by burning carbon-containing compounds in a flame and collecting the condensable. The condensable contain the desired fullerenes. Fullerene yields can be optimized and fullerene composition can be selectively varied. Fullerene yields and compositions are determined by selectively controlling flame conditions and parameters such as C/O ratio, pressure, temperature, residence time, diluent concentration and gas velocity. 4 figures.

  5. Information Entropy of Fullerenes.

    PubMed

    Sabirov, Denis Sh; ?sawa, Eiji

    2015-08-24

    The reasons for the formation of the highly symmetric C60 molecule under nonequilibrium conditions are widely discussed as it dominates over numerous similar fullerene structures. In such conditions, evolution of structure rather than energy defines the processes. We have first studied the diversity of fullerenes in terms of information entropy. Sorting 2079 structures from An Atlas of Fullerenes [ Fowler , P. W. ; Manolopoulos , D. E. An Atlas of Fullerenes ; Oxford : Clarendon , 1995 . ], we have found that the information entropies of only 14 fullerenes (<1% of the studied structures) lie between the values of C60 and C70, the two most abundant fullerenes. Interestingly, buckminsterfullerene is the only fullerene with zero information entropy, i.e., an exclusive compound among the other members of the fullerene family. Such an efficient sorting demonstrates possible relevance of information entropy to chemical processes. For this reason, we have introduced an algorithm for calculating changes in information entropy at chemical transformations. The preliminary calculations of changes in information entropy at the selected fullerene reactions show good agreement with thermochemical data. PMID:26158238

  6. Medicinal applications of fullerenes

    PubMed Central

    Bakry, Rania; Vallant, Rainer M; Najam-ul-Haq, Muhammad; Rainer, Matthias; Szabo, Zoltan; Huck, Christian W; Bonn, Gnther K

    2007-01-01

    Fullerenes have attracted considerable attention in different fields of science since their discovery in 1985. Investigations of physical, chemical and biological properties of fullerenes have yielded promising information. It is inferred that size, hydrophobicity, three-dimensionality and electronic configurations make them an appealing subject in medicinal chemistry. Their unique carbon cage structure coupled with immense scope for derivatization make them a potential therapeutic agent. The study of biological applications has attracted increasing attention despite the low solubility of carbon spheres in physiological media. The fullerene family, and especially C60, has appealing photo, electrochemical and physical properties, which can be exploited in various medical fields. Fullerene is able to fit inside the hydrophobic cavity of HIV proteases, inhibiting the access of substrates to the catalytic site of enzyme. It can be used as radical scavenger and antioxidant. At the same time, if exposed to light, fullerene can produce singlet oxygen in high quantum yields. This action, together with direct electron transfer from excited state of fullerene and DNA bases, can be used to cleave DNA. In addition, fullerenes have been used as a carrier for gene and drug delivery systems. Also they are used for serum protein profiling as MELDI material for biomarker discovery. In this review we report the aspects of medicinal applications of fullerenes. PMID:18203430

  7. Modeling compositional changes in binary solid solutions under ion bombardment: Application to the Ar+ bombardment of MgAl alloys

    NASA Astrophysics Data System (ADS)

    Reichel, F.; Jeurgens, L. P. H.; Mittemeijer, E. J.

    2006-01-01

    A model is presented which describes the steady state composition-depth profile developing in the surface adjacent region of a binary solid solution under continuous ion bombardment as a function of the bulk alloying content and the type and kinetic energy of the incident ions. To this end, the combined processes of preferential sputtering and bombardment-enhanced Gibbsian segregation are considered, while accounting for the depth and concentration dependence of the vacancy-enhanced diffusion coefficient in the solid. The model was applied to Ar+ bombardment of Mg-based MgAl alloys for various bulk Al contents (2.63-7.31at.%) and various incident Ar+ ion energies (0.1-3keV) . Very good agreement was obtained between the calculated, steady state Al concentration-depth profiles and the as-measured ones as determined experimentally by Auger electron spectroscopy, angle-resolved x-ray photoelectron spectroscopy, and ion scattering spectroscopy.

  8. Fast Atom Bombardment Mass Spectrometry.

    ERIC Educational Resources Information Center

    Rinehart, Kenneth L., Jr.

    1982-01-01

    Discusses reactions and characteristics of fast atom bombardment (FAB) mass spectroscopy in which samples are ionized in a condensed state by bombardment with xenon or argon atoms, yielding positive/negative secondary ions. Includes applications of FAB to structural problems and considers future developments using the technique. (Author/JN)

  9. [Fullerenes in radiobiology].

    PubMed

    Grebowski, Jacek; Krokosz, Anita

    2010-01-01

    Molecule of fullerene, having a spherical or ellipsoidal shape, is made of rings consisting of five or six carbon atoms, combined with conjugated pi bonds. Delocalization of pi electrons in the molecule of fullerene makes it easy to scavenge free radicals. But, despite being the effective antioxidants and radical scavengers fullerenes may be prooxidants by reactive oxygen species generation. Mammalian cells consist mainly of water (about 70%). Thus, the radical and non-radical products of water radiolysis are the basic sources of radiation damage to biomolecules. Reactive oxygen species, such as hydroxyl (HO*) and superoxide (O2-*) radicals and hydrogen peroxide (H2O2), are responsible for radiation-induced damage in aerated systems. Free radical mechanism of radiation damage suggests that scavengers of free radicals should protect cellular structures against damage. Electron donor compounds should also exhibit protective properties towards oxidized functional groups by reducing them. However, the electron transfer from fullerene to oxygen may generate superoxide radical. The shape of fullerenes allows them to act as carriers of radioactive atoms of isotopes used in the therapy and medical diagnostics. Fullerenes and their derivatives due to its properties are new promising chemicals for application in radiobiology. Fullerenes may be radioprotectors, radiosensitizer or auxiliary compounds in diagnostic imaging. What they are depends on the experimental system used. PMID:21473050

  10. Induction of antioxidant enzyme activity and lipid peroxidation level in ion-beam-bombarded rice seeds

    NASA Astrophysics Data System (ADS)

    Semsang, Nuananong; Yu, LiangDeng

    2013-07-01

    Low-energy ion beam bombardment has been used to mutate a wide variety of plant species. To explore the indirect effects of low-energy ion beam on biological damage due to the free radical production in plant cells, the increase in antioxidant enzyme activities and lipid peroxidation level was investigated in ion-bombarded rice seeds. Local rice seeds were bombarded with nitrogen or argon ion beams at energies of 29-60 keV and ion fluences of 1 × 1016 ions cm-2. The activities of the antioxidant enzymes; superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione S-transferase (GST) and lipid peroxidation level were assayed in the germinated rice seeds after ion bombardment. The results showed most of the enzyme activities and lipid peroxidation levels in both the argon and nitrogen bombarded samples were higher than those in the natural control. N-ion bombardment could induce higher levels of antioxidant enzyme activities in the rice samples than the Ar-ion bombardment. Additional effects due to the vacuum condition were found to affect activities of some antioxidant enzymes and lipid peroxidation level. This study demonstrates that ion beam bombardment and vacuum condition could induce the antioxidant enzyme activity and lipid peroxidation level which might be due to free radical production in the bombarded rice seeds.

  11. Process for fullerene functionalization

    DOEpatents

    Cahill, P.A.; Henderson, C.C.

    1995-12-12

    Di-addended and tetra-addended Buckminster fullerenes are synthesized through the use of novel organoborane intermediates. The C{sub 60}, C{sub 70}, or higher fullerene is reacted with a borane such as BH{sub 3} in a solvent such as toluene to form an organoborane intermediate. Reaction of the organoborane such as hydrolysis with water or alcohol results in the product di-addended and tetra-addended fullerene in up to 30% yields. Dihydrofullerenes and tetrahydrofullerenes are produced by the process of the invention. 7 figs.

  12. Process for fullerene functionalization

    DOEpatents

    Cahill, Paul A. (Albuquerque, NM); Henderson, Craig C. (Dublin, CA)

    1995-01-01

    Di-addended and tetra-addended Buckminster fullerenes are synthesized through the use of novel organoborane intermediates. The C.sub.60, C.sub.70, or higher fullerene is reacted with a borane such as BH.sub.3 in a solvent such as toluene to form an organoborane intermediate. Reaction of the organoborane such as hydrolysis with water or alcohol results in the product di-addended and tetra-addended fullerene in up to 30% yields. Dihydrofullerenes and tetrahydrofullerenes are produced by the process of the invention.

  13. Machine phase fullerene nanotechnology

    NASA Astrophysics Data System (ADS)

    Globus, Al; Bauschlicher, Charles W., Jr.; Han, Jie; Jaffe, Richard L.; Levit, Creon; Srivastava, Deepak

    1998-09-01

    Recent advances in fullerene science and technology suggest that it may be possible, in the distant future, to design and build atomically precise programmable machines composed largely of functionalized fullerenes. Large numbers of such machines with appropriate interconnections could conceivably create a material able to react to the environment and repair itself. This paper reviews some of the experimental and theoretical work relating to these materials, sometimes called machine phase, including the fullerene gears and high-density memory recently designed and simulated in our laboratory.

  14. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M. (1324 59th St., Downers Grove, IL 60515)

    1994-01-01

    A method of forming synthetic hydrogen defect free diamond or diamond like films on a substrate. The method involves providing vapor containing fullerene molecules with or without an inert gas, providing a device to impart energy to the fullerene molecules, fragmenting at least in part some of the fullerene molecules in the vapor or energizing the molecules to incipient fragmentation, ionizing the fullerene molecules, impinging ionized fullerene molecules on the substrate to assist in causing fullerene fragmentation to obtain a thickness of diamond on the substrate.

  15. Combustion energy of fullerene soot

    SciTech Connect

    Man, Naoki; Nagano, Yatsuhisa; Kiyobayashi, Tetsu; Sakiyama, Minoru )

    1995-02-23

    The standard energy of combustion of fullerene soot generated in arc discharge was determined to be [minus]36.0 [+-] 0.5 kJ g[sup [minus]1] by oxygen-bomb combustion calorimetry. The value was much closer to those of C[sub 60] and C[sub 70] than that of graphite. This result provides an energetic reason for the remarkable yield of fullerenes in arc discharge and supports the mechanism of fullerene formation, where fullerenes are the lowest energy products. Fullerene onion formation is interpreted in terms of energy relaxation of the fullerene soot. 20 refs., 1 tab.

  16. Conversion of fullerenes to diamonds

    DOEpatents

    Gruen, Dieter M. (1324 59th St., Downers Grove, IL 60515)

    1995-01-01

    A method of forming synthetic diamond or diamond-like films on a substrate surface. The method involves the steps of providing a vapor selected from the group of fullerene molecules or an inert gas/fullerene molecule mixture, providing energy to the fullerene molecules consisting of carbon-carbon bonds, the energized fullerene molecules breaking down to form fragments of fullerene molecules including C.sub.2 molecules and depositing the energized fullerene molecules with C.sub.2 fragments onto the substrate with farther fragmentation occurring and forming a thickness of diamond or diamond-like films on the substrate surface.

  17. Photodynamic therapy with fullerenes

    PubMed Central

    Mroz, Pawel; Tegos, George P.; Gali, Hariprasad; Wharton, Tim; Sarna, Tadeusz; Hamblin, Michael R.

    2010-01-01

    Fullerenes are a class of closed-cage nanomaterials made exclusively from carbon atoms. A great deal of attention has been focused on developing medical uses of these unique molecules especially when they are derivatized with functional groups to make them soluble and therefore able to interact with biological systems. Due to their extended ?-conjugation they absorb visible light, have a high triplet yield and can generate reactive oxygen species upon illumination, suggesting a possible role of fullerenes in photodynamic therapy. Depending on the functional groups introduced into the molecule, fullerenes can effectively photoinactivate either or both pathogenic microbial cells and malignant cancer cells. The mechanism appears to involve superoxide anion as well as singlet oxygen, and under the right conditions fullerenes may have advantages over clinically applied photosensitizers for mediating photodynamic therapy of certain diseases. PMID:17973044

  18. Combustion synthesis of fullerenes

    SciTech Connect

    Mckinnon, J.T.; Bell, W.L. ); Barkley, R.M. )

    1992-01-01

    This paper reports the isolation of C{sub 60} and C{sub 70} from combustion soot that is produced in high-temperature, low-pressure premixed flat flames. A critical parameter for high fullerene yields in combustion appears to be a very high flame temperature. Equilibrium calculations indicate that low pressures are important, but the experimental evidence is not clear at this time. Combustion synthesis yields fullerenes with a C{sub 70}/C{sub 60} ratio of about 40%, as compared with the 12% reported for electric-arc-generated fullerenes. The overall yields from carbon are very low (ca. 0.03%) but the soot studied had been produced in flames that were in no way optimized for fullerene production.

  19. Fullerenes formation in flames

    NASA Technical Reports Server (NTRS)

    Howard, Jack B.

    1993-01-01

    Fullerenes are composed of carbon atoms arranged in approximately spherical or ellipsoidal cages resembling the geodesic domes designed by Buckminster Fuller, after whom the molecules were named. The approximately spherical fullerene, which resembles a soccer ball and contains sixty atoms (C60), is called buckminsterfullerene. The fullerene containing seventy carbon atoms (C70) is approximately ellipsoidal, similar to a rugby ball. Fullerenes were first detected in 1985, in carbon vapor produced by laser evaporation of graphite. The closed shell structure, which has no edge atoms vulnerable to reaction, was proposed to explain the observed high stability of certain carbon clusters relative to that of others at high temperatures and in the presence of an oxidizing gas.

  20. Fullerene Derivatives for Medical Applications

    NASA Astrophysics Data System (ADS)

    Hirsch, Andreas

    2005-09-01

    Water-soluble fullerene derivatives have a potential for a variety of medical applications. This is due to the unique structural-, electronic and chemical properties of the fullerene core. The biological properties of suitably functionalized fullerenes range from enzyme inhibition/receptor binding, anticancer and antiviral activity, cell signalling, DNA- and genomic applications, photodynamic activation and most importantly antioxidant properties. This review focusses on the anti-HIV and antioxidant properties of a couple of water soluble fullerene derivatives.

  1. Extraterrestrial Helium Trapped in Fullerenes in the Sudbury Impact Structure

    NASA Technical Reports Server (NTRS)

    Becker, Luann; Poreda, Robert J.; Bada, Jeffrey L.

    1996-01-01

    Fullerenes (C60 and C70) in the Sudbury impact structure contain trapped helium with a He-3/He-4 ratio of 5.5 x 10(exp -4) to 5.9 x 10(exp -4). The He-3/He-4 ratio exceeds the accepted solar wind value by 20 to 30 percent and is higher by an order of magnitude than the maximum reported mantle value. Terrestrial nuclear reactions or cosmic-ray bombardment are not sufficient to generate such a high ratio. The He-3/He-4 ratios in the Sudbury fullerenes are similar to those found in meteorites and in some interplanetary dust particles. The implication is that the helium within the C60 molecules at Sudbury is of extraterrestrial origin.

  2. The topology of fullerenes

    PubMed Central

    Schwerdtfeger, Peter; Wirz, Lukas N; Avery, James

    2015-01-01

    Fullerenes are carbon molecules that form polyhedral cages. Their bond structures are exactly the planar cubic graphs that have only pentagon and hexagon faces. Strikingly, a number of chemical properties of a fullerene can be derived from its graph structure. A rich mathematics of cubic planar graphs and fullerene graphs has grown since they were studied by Goldberg, Coxeter, and others in the early 20th century, and many mathematical properties of fullerenes have found simple and beautiful solutions. Yet many interesting chemical and mathematical problems in the field remain open. In this paper, we present a general overview of recent topological and graph theoretical developments in fullerene research over the past two decades, describing both solved and open problems. WIREs Comput Mol Sci 2015, 5:96–145. doi: 10.1002/wcms.1207 Conflict of interest: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website. PMID:25678935

  3. Valence-band states of ion-bombarded polystyrene

    SciTech Connect

    Terrasi, A. ); Foti, G. ); Hwu, Y. ); Margaritondo, G. )

    1991-08-01

    Ion-bombarded polystyrene with a 0.5-keV Ar{sup +} beam has been investigated by means of photoelectron spectroscopy performed with synchrotron radiation. After a dose of 10{sup 15} ions/cm{sup 2} the evolution of the valence band of the bombarded sample towards an amorphous carbonlike configuration is reported. From the analysis of valence-band spectra we estimated the out-diffusion of hydrogen and showed that its electronic states remain well identified and stable until the hydrogen presence is about 35% with respect to the pristine sample. Finally, comparison with mass spectroscopy measurements on deuterated polystyrene has been performed to determine hydrogen evolution during the ion irradiation.

  4. Transmutation of fullerenes.

    PubMed

    Cross, R James; Saunders, Martin

    2005-03-01

    Fullerenes were pyrolyzed by subliming them into a stream of flowing argon gas and then passing them through an oven heated to approximately 1000 degrees C. C(76), C(78), and C(84) all readily lost carbons to form smaller fullerenes. In the case of C(78), some isomerization was seen. Pyrolysis of (3)He@C(76) showed that all or most of the (3)He was lost during the decomposition. C(60) passes through the apparatus with no decomposition and no loss of helium. PMID:15740143

  5. Quantum Transport through Fullerenes

    NASA Astrophysics Data System (ADS)

    Das, Shambhu; Winkler, Peter

    2011-11-01

    Quantum transport of electron pathways has recently attracted increased interest in the field of nano-technology. The study of transport through mesoscopic system can explain a wide range of interesting experimental features such as rectification, switching mechanism and transistor actions. The present study is aimed at the possible use of transmission spectra to distinguish between various isomers of certain fullerene molecules. While the famous C60 is found as a single isomer, other fullerenes come in different isomeric structures, for example, there are forty distinct isomers known for C40.

  6. Fullerenes from a fulgurite.

    PubMed

    Daly, T K; Buseck, P R; Williams, P; Lewis, C F

    1993-03-12

    Peaks at 720 and 840 atomic mass units were identified by mass spectrometry in a sample extracted from a fulgurite, which is a glassy rock that forms where lightning strikes the ground. The peaks are interpreted as arising from C(60) and C(70) and the associated peaks as produced from other fullerenes. The intense conditions generated by the lightning not only melted the rock it struck and fused the associated soil but also allowed fullerenes to form, presumably from the organic debris in the soil. PMID:17733026

  7. Fullerenes from a fulgurite

    SciTech Connect

    Daly, T.K.; Buseck, P.R.; Williams, P.; Lewis, C.F. )

    1993-03-12

    Peaks at 720 and 840 atomic mass units were identified by mass spectrometry in a sample extracted from a fulgurite, which is a glassy rock that forms where lightning strikes the ground. The peaks are interpreted as arising from C[sub 60] and C[sub 70] and the associated peaks as produced from other fullerenes. The intense conditions generated by the lightning not only melted the rock it struck and fused the associated soil but also allowed fullerenes to form, presumably from the organic debris in the soil. 29 refs., 3 figs., 1 tab.

  8. Internal energy of molecules ejected due to energetic C60 bombardment

    PubMed Central

    Garrison, Barbara J.; Postawa, Zbigniew; Ryan, Kathleen E.; Vickerman, John C.; Webb, Roger P.; Winograd, Nicholas

    2009-01-01

    The early stages of C60 bombardment of octane and octatetraene crystals are modeled using molecular dynamics simulations with incident energies of 5-20 keV. Using the AIREBO potential, which allows for chemical reactions in hydrocarbon molecules, we are able to investigate how the projectile energy is partitioned into changes in potential and kinetic energy as well as how much energy flows into reacted molecules and internal energy. Several animations have been included to illustrate the bombardment process. The results show that the material near the edge of the crater can be ejected with low internal energies and that ejected molecules maintain their internal energies in the plume, in contrast to a collisional cooling mechanism previously proposed. In addition, a single C60 bombardment was able to create many free and reacted H atoms which may aid in the ionization of molecules upon subsequent bombardment events. PMID:19228010

  9. Combustion Synthesis of Fullerenes and Fullerenic Nanostructures In Microgravity

    NASA Technical Reports Server (NTRS)

    Howard, Jack B.; Brooker, John E. (Technical Monitor)

    2002-01-01

    The objectives of the proposed research were to determine the effects of gravity on fullerenes formation in flames and, based on the observed effects, to develop fundamental understanding of fullerenes formation and to identify engineering principles for fullerenes production. The research method consisted of the operation of laminar diffusion flames under normal- and reduced-gravity conditions, and the collection from the flames and subsequent analysis of condensables including any fullerenes present, using coupled high performance liquid chromatography/mass spectrometry and high resolution transmission electron microscopy. The focus included fullerene molecules C60 and C70 and fullerenic nanostructures including tubes, spherules and other shapes. The normal-gravity experiments were performed at MIT and complementary reduced-gravity experiments were to have been contributed by NASA. The independent variables of interest are gravity, fuel type, fuel/oxygen ratio, pressure, gas velocity at burner, diluent type and concentration. Given the large number of variables and the absence of data on either fullerene formation in diffusion flames or gravitational effects on fullerene formation in diffusion or premixed flames, the first part of the work was exploratory while the later part involved detailed study of the most interesting mechanisms. Samples of condensable material from laminar low pressure benzene/argon/oxygen diffusion flames were collected and analyzed by high-performance liquid chromatography to determine the yields of fullerenes, and by high-resolution transmission electron microscopy (HRTEM) to characterize the fullerenic material, i.e., curved-layer nanostructures, on and within the soot particles. The highest concentration of fullerenes was always detected just above the visible stoichiometric surface of a flame. The percentage of fullerenes in the condensable material increases with decreasing pressure. The overall highest amount of fullerenes was found for a surprisingly high dilution fuel with argon. The maximum flame temperature seems to be of minor importance in fullerene formation. The HRTEM analysis of the soot showed an increase of the curvature of the carbon layers, and hence increased fullerenic character. After this maximum, the curvature decreases. In addition to the soot, the samples included fullerenic nanostructures, such as tubes and spheroids including highly-ordered multilayered or onion-like structures. The soot itself shows highly ordered regions that appear to have been cells of ongoing fullerenic nanostructure formation.

  10. Geological occurrence of fullerenes

    SciTech Connect

    Buseck, P.R.; Tsipursky, S.J.; Wang, S. ); Hettich, R. )

    1992-01-01

    Using HRTEM imaging, the authors found C[sub 60] and C[sub 70] fullerenes in shungite, a Precambrian carbon-rich rock from Karelia, Russia. Compositionally, shungite represents coals of the meta-anthracite rank, characterized by low ash and sulfur contents, low volatile yields, and high carbon contents. The shungite occurs within metamorphosed sediments. The overlying rocks consist of gray dolomitized sandstones and poorly sorted silts and clays; the underlying rocks are not exposed. The shungite consists of masses containing up to 99% carbon. Diabase is interstratified with shungite-bearing rocks, and the shungite concentration increases with proximity to the diabase. Their sample comes from inclusions in the diabase. In the HRTEM images the fullerenes appear round (presumably roughly spherical in three dimensions), with white rims and black centers, almost identical to images of synthetic C[sub 60] molecules. Following the HRTEM observations, the fullerene identities were confirmed, first by time-of-flight mass spectrometry and then by more precise laser ablation, laser desorption, and thermal desorption ionization plus Fourier transform (FT) mass spectrometry. These measurements verified that the fullerenes were not generated by the laser ionization event. HRTEM images show that locally they occur in ordered arrays that resemble crystals of synthetic C[sub 60]. FT mass spectra show that the C-13/C-12 isotopic ratios for C[sub 60] and C[sub 70] fall within the normal range of terrestrial isotopic values.

  11. Optical, mass, and auger spectra from e-bombarded KBr

    SciTech Connect

    Arakawa, E.T.; Kamada, M.

    1988-01-01

    We have measured the mass spectrum and optical emission lines of neutral potassium atoms ejected from KBr at T = 300/degree/K and 443/degree/K bombarded by 2-keV electrons. The room-temperature data may be complicated by the nonstoichiometry of the alkali-enriched sample surface and seem difficult to interpret. The high-temperature sample, which maintains the proper stoichiometry, produces data in support of gas-phase excitation of alkali atoms desorbed from the surface. 15 refs., 4 figs.

  12. Use of fullerenes in cosmetics.

    PubMed

    Lens, Marko

    2009-01-01

    As cosmetic technology advances, there is an increasing need to use new active ingredients in the development of cosmetic products. In the last few years application of fullerene C(60) and its derivates in cosmetics has been intensively tested. Fullerenes display a wide range of biological activities. Potent scavenging capacities against radical oxygen species (ROS) and excellent potential as biological antioxidants made fullerenes suitable active compounds in the preparation of skin rejuvenation cosmetic formulations. Currently published evidence on biological activities of fullerenes relevant for their cosmetic use and examples of published patents to illustrate application of fullerenes in cosmetic technology are presented. Future trends in the development of cosmetic formulations including fullerenes are discussed. PMID:19519567

  13. Surface composition and erosion yields for CVD TiB/sub 2/ films subjected to low energy deuterium ion bombardment

    SciTech Connect

    Nelson, G.C.; Borders, J.A.

    1980-01-01

    The surface composition and low energy sputter yield of deuterium bombarded CVD TiB/sub 2/ films have been measured. The sputter yield increases with energy up to 1 keV where it reaches a maximum of 0.024 atoms/ion. Above 1 keV the yield decreases due to ion penetration effects. Surface composition measurements using Auger, x-ray photoelectron and secondary ion mass spectroscopies show that a surface layer about 200 A thick is depleted in B during 2 keV deuterium bombardment. This effect is attributed to preferential sputtering. Oxides and deuterides of titanium are also observed on the deuterium bombardment TiB/sub 2/ surface.

  14. Cycloaddition model for fullerene formation

    SciTech Connect

    Strout, D.L.; Scuseria, G.E.

    1996-04-18

    Since their discovery, the fullerenes have challenged scientists with a wide array of problems concerning their properties, behavior, and potential applications. One such fundamental question is that of the assembly of these carbon cages. Much effort has been directed at obtaining an understanding of the process whereby graphite is transformed into fullerenes. In a previous work, we introduced a novel interpretation of the ion chromatography results from fullerene generation experiments. In this work, that interpretation is expanded and ab initio calculations are performed to illustrate how the model explains the experimental results. This `cycloaddition model` is then used to develop a plausible fullerene assembly mechanism. 19 refs., 12 figs., 10 tabs.

  15. Ion bombardment in RF photoguns

    SciTech Connect

    Pozdeyev,E.; Kayran, D.; Litvinenko, V. N.

    2009-05-04

    A linac-ring eRHIC design requires a high-intensity CW source of polarized electrons. An SRF gun is viable option that can deliver the required beam. Numerical simulations presented elsewhere have shown that ion bombardment can occur in an RF gun, possibly limiting lifetime of a NEA GaAs cathode. In this paper, we analytically solve the equations of motion of ions in an RF gun using the ponderomotive potential of the Rf field. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper discusses possible mitigation techniques that can reduce the rate of ion bombardment.

  16. Cereal transformation through particle bombardment

    NASA Technical Reports Server (NTRS)

    Casas, A. M.; Kononowicz, A. K.; Bressan, R. A.; Hasegawa, P. M.; Mitchell, C. A. (Principal Investigator)

    1995-01-01

    The review focuses on experiments that lead to stable transformation in cereals using microprojectile bombardment. The discussion of biological factors that affect transformation examines target tissues and vector systems for gene transfer. The vector systems include reporter genes, selectable markers, genes of agronomic interest, and vector constructions. Other topics include physical parameters that affect DNA delivery, selection of stably transformed cells and plant regeneration, and analysis of gene expression and transmission to the progeny.

  17. Metal ion bombardment of onion skin cell wall

    SciTech Connect

    Sangyuenyongpipat, S.; Vilaithong, T.; Yu, L.D.; Verdaguer, A.; Ratera, I.; Ogletree, D.F.; Monteiro, O.R.; Brown, I.G.

    2004-05-10

    Ion bombardment of living cellular material is a novel subfield of ion beam surface modification that is receiving growing attention from the ion beam and biological communities. Although it has been demonstrated that the technique is sound, in that an adequate fraction of the living cells can survive both the vacuum environment and energetic ion bombardment, there remains much uncertainty about the process details. Here we report on our observations of onion skin cells that were subjected to ion implantation, and propose some possible physical models that tend to support the experimental results. The ion beams used were metallic (Mg, Ti, Fe, Ni, Cu), mean ion energy was typically 30keV, and the implantation fluence was in the range 1014 1016 ions/cm2. The cells were viewed using Atomic Force Microscopy, revealing the formation of microcrater-like structures due to ion bombardment. The implantation depth profile was measured with Rutherford backscattering spectrometry and compared to the results of the TRIM, T-DYN and PROFILE computer codes.

  18. Characterizing the Early Impact Bombardment

    NASA Technical Reports Server (NTRS)

    Bogard, Donald D.

    2005-01-01

    The early bombardment revealed in the larger impact craters and basins on the moon was a major planetary process that affected all bodies in the inner solar system, including the Earth and Mars. Understanding the nature and timing of this bombardment is a fundamental planetary problem. The surface density of lunar impact craters within a given size range on a given lunar surface is a measure of the age of that surface relative to other lunar surfaces. When crater densities are combined with absolute radiometric ages determined on lunar rocks returned to Earth, the flux of large lunar impactors through time can be estimated. These studies suggest that the flux of impactors producing craters greater than 1 km in diameter has been approximately constant over the past approx. 3 Gyr. However, prior to 3.0 - 3.5 Gyr the impactor flux was much larger and defines an early bombardment period. Unfortunately, no lunar surface feature older than approx. 4 Gyr is accurately dated, and the surface density of craters are saturated in most of the lunar highlands. This means that such data cannot define the impactor flux between lunar formation and approx. 4 Gyr ago.

  19. The smallest fullerene without a spiral

    NASA Astrophysics Data System (ADS)

    Brinkmann, Gunnar; Goedgebeur, Jan; McKay, Brendan D.

    2012-01-01

    In this note, we give the result of a computer search for the smallest fullerene that does not allow a face spiral code as used by Manolopoulos and Fowler and adopted in IUPAC recommendations for fullerene nomenclature. The search enumerated all the small fullerenes on up to 400 vertices and the conclusion is that the smallest fullerene without a face spiral has 380 vertices.

  20. Diamond film growth from fullerene precursors

    DOEpatents

    Gruen, Dieter M. (Downers Grove, IL); Liu, Shengzhong (Woodridge, IL); Krauss, Alan R. (Naperville, IL); Pan, Xianzheng (Woodridge, IL)

    1997-01-01

    A method and system for manufacturing diamond film. The method involves forming a fullerene vapor, providing a noble gas stream and combining the gas with the fullerene vapor, passing the combined fullerene vapor and noble gas carrier stream into a chamber, forming a plasma in the chamber causing fragmentation of the fullerene and deposition of a diamond film on a substrate.

  1. Chiral fullerenes from asymmetric catalysis.

    PubMed

    Maroto, Enrique E; Izquierdo, Marta; Reboredo, Silvia; Marco-Martnez, Juan; Filippone, Salvatore; Martn, Nazario

    2014-08-19

    Fullerenes are among the most studied molecules during the last three decades, and therefore, a huge number of chemical reactions have been tested on these new carbon allotropes. However, the aim of most of the reactions carried out on fullerenes has been to afford chemically modified fullerenes that are soluble in organic solvents or even water in the search for different mechanical, optical, or electronic properties. Therefore, although a lot of effort has been devoted to the chemical functionalization of these molecular allotropes of carbon, important aspects in the chemistry of fullerenes have not been properly addressed. In particular, the synthesis of chiral fullerenes at will in an efficient manner using asymmetric catalysis has not been previously addressed in fullerene science. Thus, despite the fact that the chirality of fullerenes has always been considered a fundamental issue, the lack of a general stereoselective synthetic methodology has restricted the use of enantiopure fullerene derivatives, which have usually been obtained only after highly expensive HPLC isolation on specific chiral columns or prepared from a pool of chiral starting materials. In this Account, we describe the first stereodivergent catalytic enantioselective syntheses in fullerene science, which have allowed the highly efficient synthesis of enantiomerically pure derivatives with total control of the stereochemical result using metallic catalysts and/or organocatalysts under very mild conditions. Density functional theory calculations strongly support the experimental findings for the assignment of the absolute configuration of the new stereocenters, which has also been ascertained by application of the sector rule and single-crystal X-ray diffraction. The use of the curved double bond of fullerene cages as a two-?-electron component in a variety of stereoselective cycloaddition reactions represents a challenging goal considering that, in contrast to most of the substituted olefins used in these reactions, pristine fullerene is a noncoordinating dipolarophile. The aforementioned features make the study of stereoselective 1,3-dipolar cycloadditions onto fullerenes a unique scenario to shed light onto important mechanistic aspects. On the other hand, the availability of achiral starting materials as well as the use of nonexpensive asymmetric catalysts should provide access to chiral fullerenes and their further application in a variety of different fields. In this regard, in addition to biomedical applications, chiral fullerenes are of interest in less-studied areas such as materials science, organic electronics, and nanoscience, where control of the order and morphology at the nanometer scale are critical issues for achieving better device efficiencies. PMID:25080165

  2. Intermolecular nitrile oxide transfer in fullerene isoxazolines

    SciTech Connect

    Pogue, R.T.; Meier, M.S.; Thomas, C.; Majidi, V.

    1995-12-31

    Mass spectrometric analysis of fullerene derivatives often requires very different conditions and produces very different results than are expected when examining underivatized fullerenes. Frequently, mass spectra of derivatives have relatively small molecular ion peaks and are dominated by fullerene ion peak at high masses. The need for reliable mass spectrometric methods is increasing as new classes of fullerene derivatives are introduced. One such class of derivatives, the fullerene isoxazolines, is examined in this presentation.

  3. The effects of ion bombardment of ultra-high molecular weight polyethylene

    NASA Astrophysics Data System (ADS)

    Turos, A.; Abdul-Kader, A. M.; Grambole, D.; Jagielski, J.; Pi?tkowska, A.; Madi, N. K.; Al-Maadeed, M.

    2006-08-01

    Ion bombardment is a suitable tool to improve tribological properties of polymers. In this study UHMWPE samples were bombarded with 130 keV He ions to the fluences ranging from 1 1014 to 2 1016 cm-2. RBS and NRA techniques were applied to study compositional transformations induced by ion beam bombardment. Important hydrogen release was observed with increasing ion dose and was correlated with the linear energy transfer (LET). Another important effect observed was the rapid oxidation of samples, which apparently occurs after exposure of implanted samples to the air. Oxygen uptake continues during the prolonged storage of the samples in the air at RT. Up to 10 at.% of oxygen can be incorporated in the implanted layer. Changes of surface layer composition produced important increase in the layer hardness. Scratch tests revealed that the hardening of surface layers does not lead to their higher brittleness.

  4. An ion beam deceleration lens for ultra-low-energy ion bombardment of naked DNA

    NASA Astrophysics Data System (ADS)

    Thopan, P.; Prakrajang, K.; Thongkumkoon, P.; Suwannakachorn, D.; Yu, L. D.

    2013-07-01

    Study of low-energy ion bombardment effect on biological living materials is of significance. High-energy ion beam irradiation of biological materials such as organs and cells has no doubt biological effects. However, ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range. To investigate effects from very-low-energy ion bombardment on biological materials, an ion beam deceleration lens is necessary for uniform ion energy lower than keV. A deceleration lens was designed and constructed based on study of the beam optics using the SIMION program. The lens consisted of six electrodes, able to focus and decelerate primary ion beam, with the last one being a long tube to obtain a parallel uniform exiting beam. The deceleration lens was installed to our 30-kV bioengineering-specialized ion beam line. The final decelerated-ion energy was measured using a simple electrostatic field to bend the beam to range from 10 eV to 1 keV controlled by the lens parameters and the primary beam condition. In a preliminary test, nitrogen ion beam at 60 eV decelerated from a primary 20-keV beam bombarded naked plasmid DNA. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks. The study demonstrated that the ion bombardment with energy as low as several-tens eV was possible to break DNA strands and thus potential to cause genetic modification of biological cells.

  5. Gel behavior of keV ion irradiated polystyrene

    SciTech Connect

    Calcagno, L.; Foti, G.; Licciardello, A.; Puglisi, O.

    1988-10-17

    Among the chemical and physical modifications induced by ion bombardment of polymers, the solubility changes are very important because of technological application for lithography in microelectronic devices. Solubility changes due to the occurrence of crosslinkings have been followed on monodisperse and polydisperse polystyrene after ion irradiations (10/sup 11/--10/sup 14/ ions/cm/sup 2/, keV energy). By using the Inokuty gel theory (M. Inokuti J. Appl. Phys. 38, 2999 (1963)), the chemical yield (crosslinking/eV) has been determined for different molecular weights and molecular weight distributions.

  6. High depth resolution SIMS analysis using metal cluster complex ion bombardment

    NASA Astrophysics Data System (ADS)

    Tomita, M.; Kinno, T.; Koike, M.; Tanaka, H.; Takeno, S.; Fujiwara, Y.; Kondou, K.; Teranishi, Y.; Nonaka, H.; Fujimoto, T.; Kurokawa, A.; Ichimura, S.

    2008-03-01

    SIMS depth profiles were measured using metal cluster complex ions of Ir4(CO)7+ as a primary ion beam in order to obtain high depth resolution. Depth resolution was evaluated as a function of primary ion species, energy and incident angle using a multiple boron delta-doped silicon sample. The depth resolution obtained using cluster ion bombardment was considerably better than that obtained by oxygen ion bombardment under the same bombardment condition due to reduction of atomic mixing in the depth. The best depth resolution was 0.9 nm under the bombardment condition of 5 keV, 45 with oxygen flooding, which approaches the value measured with state of the art SIMS analyses. However, depth resolution was not improved by decreasing the cluster ion energy (less than 5 keV), even though the roughness of the sputtered surface was suppressed. The limit of depth resolution improvement may be caused by a carbon cover-layer that prevents the formation of surface oxide that buffers atomic mixing. To overcome this issue, it will be necessary to eliminate carbon from the cluster ion.

  7. Ion bombardment induced changes in the optical and electrical properties of polycarbonate

    NASA Astrophysics Data System (ADS)

    Radwan, R. M.; Abdul-Kader, A. M.; El-Hag Ali, A.

    2008-08-01

    The changes in the optical and electrical properties of polycarbonate (PC) films, bombarded with He and Ar ion beams, have been studied. The PC films were divided into two groups where the first group was bombarded with 130 keV He ions of fluences ranged from 1 10 14 cm -2 to 2 10 16 cm -2, while the second one was bombarded with 320 keV Ar of fluences (1 10 13 cm -2 and 1 10 15 cm -2). The surface morphology of the unirradiated and irradiated PC films was studied using scanning electron microscopy (SEM) technique. The optical properties of the two groups have been carried out using UV-Vis spectrophotometer and the direct current (DC) electrical conductivity was also performed. The obtained results showed a decrease in the optical energy gap, the optical activation energy and the electrical activation energy with increasing the fluence of both He and Ar ions. Meanwhile, an increase in the DC conductivity was obtained with increasing the fluence of the ions. The bombardment of the PC films with He and Ar ion beams induced formation of carbon clusters near the polymer surface and, also, resulted in scission in the polymer chains.

  8. Bombarding effects of gas cluster ion beams on sapphire surfaces: Characteristics of modified layers and their mechanical and optical properties

    SciTech Connect

    Takeuchi, D.; Matsuo, J.; Yamada, I.

    1996-12-31

    Gas cluster ions contain tens, hundreds or even more than thousands of atoms or molecules as ionized particles. It has been shown that the bombarding effects of gas cluster ions on solid surfaces are quite different from those by monomer ions and involve unique material processing characteristics. In order to make clear the bombarding effects, a study of surface modification of sapphire by Ar and CO{sub 2} gas cluster ion beams has been performed. Thickness of the damaged layer and surface roughness produced on sapphire depends strongly on cluster ion energy. Damage layer thickness on a sapphire surface bombarded by 150 keV clusters with average size of about 3,000 atoms was 40 {angstrom}. No significant difference was observed in IR transmittance after cluster bombardment. Mechanical properties of sapphire surfaces can be changed by cluster irradiation at a dose of 10{sup 11} ions/cm{sup 2}.

  9. Glycofullerenes: Sweet fullerenes vanquish viruses

    NASA Astrophysics Data System (ADS)

    Vidal, Sébastien

    2016-01-01

    Fullerene-based dendritic structures coated with 120 sugars can be made in high yields in a relatively short sequence of reactions. The mannosylated compound is shown to inhibit Ebola infection in cells more efficiently than monofullerene-based glycoclusters.

  10. Closed network growth of fullerenes

    NASA Astrophysics Data System (ADS)

    Dunk, Paul W.; Kaiser, Nathan K.; Hendrickson, Christopher L.; Quinn, John P.; Ewels, Christopher P.; Nakanishi, Yusuke; Sasaki, Yuki; Shinohara, Hisanori; Marshall, Alan G.; Kroto, Harold W.

    2012-05-01

    Tremendous advances in nanoscience have been made since the discovery of the fullerenes; however, the formation of these carbon-caged nanomaterials still remains a mystery. Here we reveal that fullerenes self-assemble through a closed network growth mechanism by incorporation of atomic carbon and C2. The growth processes have been elucidated through experiments that probe direct growth of fullerenes upon exposure to carbon vapour, analysed by state-of-the-art Fourier transform ion cyclotron resonance mass spectrometry. Our results shed new light on the fundamental processes that govern self-assembly of carbon networks, and the processes that we reveal in this study of fullerene growth are likely be involved in the formation of other carbon nanostructures from carbon vapour, such as nanotubes and graphene. Further, the results should be of importance for illuminating astrophysical processes near carbon stars or supernovae that result in C60 formation throughout the Universe.

  11. Closed network growth of fullerenes.

    PubMed

    Dunk, Paul W; Kaiser, Nathan K; Hendrickson, Christopher L; Quinn, John P; Ewels, Christopher P; Nakanishi, Yusuke; Sasaki, Yuki; Shinohara, Hisanori; Marshall, Alan G; Kroto, Harold W

    2012-01-01

    Tremendous advances in nanoscience have been made since the discovery of the fullerenes; however, the formation of these carbon-caged nanomaterials still remains a mystery. Here we reveal that fullerenes self-assemble through a closed network growth mechanism by incorporation of atomic carbon and C(2). The growth processes have been elucidated through experiments that probe direct growth of fullerenes upon exposure to carbon vapour, analysed by state-of-the-art Fourier transform ion cyclotron resonance mass spectrometry. Our results shed new light on the fundamental processes that govern self-assembly of carbon networks, and the processes that we reveal in this study of fullerene growth are likely be involved in the formation of other carbon nanostructures from carbon vapour, such as nanotubes and graphene. Further, the results should be of importance for illuminating astrophysical processes near carbon stars or supernovae that result in C(60) formation throughout the Universe. PMID:22617295

  12. Ion Bombardment Experiments Suggesting an Origin for Organic Particles in Pre-Cometary and Cometary Ices

    NASA Technical Reports Server (NTRS)

    Wdowiak, Thomas J.; Robinson, Edward L.; Flickinger, Gregory C.; Boyd, David A.

    1997-01-01

    Simple molecules frozen as mantles of interstellar and circumstellar grains and incorporated into comets are subjected to ion bombardment in the form of cosmic rays, stellar flares, stellar winds, and ions accelerated in stellar wind shocks. The total expected dosage for the variety of situations range from 10 eV/molecule for interplanetary dust subjected to solar flares to 10(exp 6) eV/molecule for material in the T Tauri environment. Utilizing a Van de Graaff accelerator and a target chamber having cryogenic and mass spectrometer capabilities, we have bombarded frozen gases in the temperature range of 10 K to 30 K with 175 keV protons. After irradiation, removal of the ice by sublimation at an elevated temperature in vacuum reveals a fluffy residue. These experiments suggest that processes resulting in the formation of organic particles found in the coma of Comet Halley, "CHON", may have included ion bombardment. Also, the moderate energy (100 keV to 500 keV) shock accelerated ion environment of bipolar outflow of stars in the planetary nebula stage such as the Red Rectangle, could produce complex molecular species which emit the observed unidentified infrared bands at 3.3 micro-m, 6.2 micro-m, 7.7 micro-m, 8.6 micro-m, and 11.3 micro-m.

  13. Fullerene derivatization by pyrolytic reaction

    SciTech Connect

    Hoke, S.H. II; Molstad, J.; Yang, Sheng Sheng; Kahr, B.; Cooks, R.G.

    1994-12-31

    The first observation of C{sub 60} was made in a time-of-flight mass spectrometer and mass spectrometry continues to play a major role in the identification of fullerenes and fullerene derivatives. Since the discovery of a method of producing macroscopic quantities of fullerenes, many fullerene derivatives have been reported and an increasing number have been fully characterized. The identification of the molecular weight of fullerene derivatives in reaction mixtures has been invaluable. Mass spectrometry has provided evidence for a plethora of novel compounds including metallic, alkyl, aryl, benzyl, phenyl, hydroxy, amino, fluoro, epoxy, and hydro fullerenes. In this study, new aromatic derivatives of C{sub 60} are produced by reaction with aryne or aryl radicals which are pyrolytically generated. The products are characterized by desorption chemical ionization mass spectrometry in the negative ion mode. Because of the high electron affinity of C{sub 60} abundant radical anions of C{sub 60} and derivatives are produced under chemical ionization conditions and can be detected in crude reaction mixtures with no sample preparation.

  14. Analysis of TOF-SIMS spectra from fullerene compounds

    NASA Astrophysics Data System (ADS)

    Kato, N.; Yamashita, Y.; Iida, S.; Sanada, N.; Kudo, M.

    2008-12-01

    We analyzed TOF-SIMS spectra obtained from three different size of fullerenes (C 60, C 70 and C 84) by using Ga +, Au + and Au 3+ primary ion beams and investigated the fragmentation patterns, the enhancement of secondary ion yields and the restraint of fragmentation by using cluster primary ion beams compared with monoatomic primary ion beams. In the TOS-SIMS spectra from C 70 and C 84, it was found that a fragment ion, identified as C 60+ ( m/ z = 720), showed a relatively high intensity compared with that of other fragment ions related to C 2 depletion. It was also found that the Au 3+ bombardment caused intensity enhancement of intact molecules (C 60+, C 70+ and C 84+) and restrained the fragmentation due to C 2 depletion.

  15. Energetic ion bombardment of Ag surfaces by C60+ and Ga+ projectiles.

    PubMed

    Sun, Shixin; Szakal, Christopher; Winograd, Nicholas; Wucher, Andreas

    2005-10-01

    The ion bombardment-induced release of particles from a metal surface is investigated using energetic fullerene cluster ions as projectiles. The total sputter yield as well as partial yields of neutral and charged monomers and clusters leaving the surface are measured and compared with corresponding data obtained with atomic projectile ions of similar impact kinetic energy. It is found that all yields are enhanced by about one order of magnitude under bombardment with the C60+ cluster projectiles compared with Ga+ ions. In contrast, the electronic excitation processes determining the secondary ion formation probability are unaffected. The kinetic energy spectra of sputtered particles exhibit characteristic differences which reflect the largely different nature of the sputtering process for both types of projectiles. In particular, it is found that under C60+ impact (1) the energy spectrum of sputtered atoms peaks at significantly lower kinetic energies than for Ga+ bombardment and (2) the velocity spectra of monomers and dimers are virtually identical, a finding which is in pronounced contrast to all published data obtained for atomic projectiles. The experimental findings are in reasonable agreement with recent molecular dynamics simulations. PMID:16099165

  16. Production Of Fullerenic Soot In Flames

    DOEpatents

    Howard, Jack B.; Vander Sande, John B.; Chowdhury, K. Das

    2000-12-19

    A method for the production of fullerenic nanostructures is described in which unsaturated hydrocarbon fuel and oxygen are combusted in a burner chamber at a sub-atmospheric pressure, thereby establishing a flame. The condensibles of the flame are collected at a post-flame location. The condensibles contain fullerenic nanostructures, such as single and nested nanotubes, single and nested nanoparticles and giant fullerenes. The method of producing fullerenic soot from flames is also described.

  17. Production of fullerenic nanostructures in flames

    DOEpatents

    Howard, Jack B.; Vander Sande, John B.; Chowdhury, K. Das

    1999-01-01

    A method for the production of fullerenic nanostructures is described in which unsaturated hydrocarbon fuel and oxygen are combusted in a burner chamber at a sub-atmospheric pressure, thereby establishing a flame. The condensibles of the flame are collected at a post-flame location. The condensibles contain fullerenic nanostructures, such as single and nested nanotubes, single and nested nanoparticles and giant fullerenes. The method of producing fullerenic soot from flames is also described.

  18. Diamond film growth from fullerene precursors

    DOEpatents

    Gruen, D.M.; Liu, S.; Krauss, A.R.; Pan, X.

    1997-04-15

    A method and system are disclosed for manufacturing diamond film. The method involves forming a fullerene vapor, providing a noble gas stream and combining the gas with the fullerene vapor, passing the combined fullerene vapor and noble gas carrier stream into a chamber, forming a plasma in the chamber causing fragmentation of the fullerene and deposition of a diamond film on a substrate. 10 figs.

  19. 30 years of cosmic fullerenes

    NASA Astrophysics Data System (ADS)

    Bern, O.; Montillaud, J.; Mulas, G.; Joblin, C.

    2015-12-01

    In 1985, ``During experiments aimed at understanding the mechanisms by which long-chain carbon molecules are formed in interstellar space and circumstellar shells'', Harry Kroto and his collaborators serendipitously discovered a new form of carbon: fullerenes. The most emblematic fullerene (i.e. C_{60} ``buckminsterfullerene''), contains exactly 60 carbon atoms organized in a cage-like structure similar to a soccer ball. Since their discovery impacted the field of nanotechnologies, Kroto and colleagues received the Nobel prize in 1996. The cage-like structure, common to all fullerene molecules, gives them unique properties, in particular an extraordinary stability. For this reason and since they were discovered in experiments aimed to reproduce conditions in space, fullerenes were sought after by astronomers for over two decades, and it is only recently that they have been firmly identified by spectroscopy, in evolved stars and in the interstellar medium. This identification offered the opportunity to study the molecular physics of fullerenes in the unique physical conditions provided by space, and to make the link with other large carbonaceous molecules thought to be present in space : polycyclic aromatic hydrocarbons.

  20. Fullerene materials: Synthesis and applications

    NASA Astrophysics Data System (ADS)

    Cassell, Alan Mitchell

    Chapter 1 describes the purification of gram quantities of Csb{70} using activated charcoal flash chromatography columns. A detailed procedure on the use of these columns as well as the analysis of the purified material is given. Chapter 2 describes the production and analysis of metal-containing fullerene soots produced by plasma arc discharge. A method for dispersing nanometer-sized metal particles in porous graphite rods is presented. The metal/graphite rods are then consumed in an arc discharge reactor to form the metal-containing fullerene soots. Transmission electron microscopy and powder X-ray diffraction analysis are used to characterize the soots. Chapter 3 describes the complexation of DNA with a fullerene ammonium salt. The fullerene ammonium salt/DNA complex is easily imagable using transmission electron microscopy. The formation of these DNA complexes, as well as the preparation for imaging is discussed. Also described is the preparation of a ammonium salt derivative of ferrocene which is complexed with DNA. Chapter 4 describes the self-assembly of fullerene ammonium salts. The salts assemble into vesicle and tubule type structures. Transmission electron microscopy, powder X-ray diffraction, and energy dispersive X-ray analysis is used to investigate the structures.

  1. Electronic structures of endohedral fullerenes

    SciTech Connect

    Jin, Changming; Hettich, R.L.; Puretzky, A.A.; Ying, Z.C.; Haufler, R.E.; Compton, R.N.

    1994-12-31

    Fullerenes with different elements trapped inside the cage have been the subject of active research both experimentally and theoretically ever since the initial discovery of C{sub 60}. La@C{sub n}, were the first endohedral fullerenes produced both in gas phase and in macroscopic quantities. Early electron spin resonance investigation of La@C{sub 82} by R.D. Johnson, et.al indicated that La transfer nearly all of the three valence electrons to the fullerene cage, forming a La{sup 3+}@C{sub 82}{sup 3-} complex. Theoretical calculations also have shown that La transfers its valence electrons to the fullerene cage in molecules of La@C{sub n}. Investigations with ultraviolet photoelectron spectroscopy by L. Wang, et.al. indicated that attaching a potassium atom outside the C{sub 60} cage lowers the electron affinity (EA) while trapping Ca atom inside the C{sub 60} sphere increases the EA compared with parent C{sub 60} molecule. These results indicate that metallofullerenes appear to have substantially lower ionization potentials (IP) and higher EA than empty fullerenes.

  2. The story of making fullerenes

    NASA Astrophysics Data System (ADS)

    Krtschmer, Wolfgang

    2011-06-01

    Carbon is the most abundant condensable element in space. Our attempts to produce interstellar-like graphitic grains unexpectedly led to the discovery of a method for fullerene production in bulk amounts. These works opened the door for an entirely new branch of materials research and carbon chemistry. Here I present the various phases and steps of our work which, with interludes, lasted from 1983 to 1990. The starting point was the discovery of unexplained UV absorptions in the soot samples we had produced, while the endpoint was marked by the extraction of fullerenes in crystalline form from just these samples.Carbon is the most abundant condensable element in space. Our attempts to produce interstellar-like graphitic grains unexpectedly led to the discovery of a method for fullerene production in bulk amounts. These works opened the door for an entirely new branch of materials research and carbon chemistry. Here I present the various phases and steps of our work which, with interludes, lasted from 1983 to 1990. The starting point was the discovery of unexplained UV absorptions in the soot samples we had produced, while the endpoint was marked by the extraction of fullerenes in crystalline form from just these samples. This article was submitted as part of a collection highlighting papers from the Fullerene Silver Anniversary Symposium Conference held in Crete in October 2010.

  3. Ion bombardment investigations of impregnated cathodes

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaobing; Gaertner, Georg

    2003-06-01

    Ion bombardment is one of the important factors limiting the performance of impregnated cathodes (=Ba dispenser cathodes) in high end television tubes or in colour monitor tubes. Hence, when designing a new gun with, e.g. higher electron beam current density, it is important also to model the influence of ion bombardment. Therefore, relations between basic parameters as a function of temperature need to be known quantitatively. In this paper, the emission slump of impregnated cathodes has been analyzed in a diode configuration in UHV with a differentially pumped Ar ion gun. The emission degeneration during and regeneration periods after ion bombardment have been investigated as function of cathode temperature, ion current and ion energy. One of the important results is, that the degeneration time coefficient is only weakly dependent on ion energy. The data matrix obtained can be used to improve the ion bombardment model applied in new electron gun design.

  4. Plasma ion source for in situ ion bombardment in a soft x-ray magnetic scattering diffractometer

    SciTech Connect

    Lengemann, Daniel; Engel, Dieter; Ehresmann, Arno

    2012-05-15

    A new plasma ion source for in situ keV He ion bombardment of solid state samples or thin films was designed and built for ion fluences between 1 x 10{sup 12} and 1 x 10{sup 17} ions/cm{sup 2}. The system was designed to be mounted to different diffraction chambers for soft x-ray resonant magnetic scattering. Without breaking the vacuum due to He-ion bombardment, structural and magnetic modifications of the samples can be studied in situ and element specifically.

  5. Pseudorotation in fullerene anions

    NASA Astrophysics Data System (ADS)

    Dunn, Janette L.; Hands, Ian D.; Bates, Colin A.

    2007-07-01

    Jahn-Teller (JT) problems are often characterised by an adiabatic potential energy surface (APES) containing either a set of isoenergetic wells or a trough of equivalent-energy points, which may be warped by higher-order coupling terms or anisotropic effects. In all three cases, the JT effect will be dynamic. Either tunnelling between the wells or rotation (of a distortion) around the trough will restore the original symmetry of the system. This motion is referred to as pseudorotation. It should be possible to observe a JT system in a distorted geometry if measurements are made on a sufficiently short timescale. In various cubic systems, this timescale has been calculated to be the order of picoseconds. Such timescales are accessible using modern methods of ultrafast spectroscopy. Measurements of pseudorotation rates can lead to important information on the strength and nature of the JT coupling present. We will present analytical calculations that allow the rate of pseudorotation to be determined in terms of the vibronic coupling parameters. We will show how these results can be applied to E ⊗ e systems and then to the more complicated system applicable to C60- anions. This is of particular interest because of the high icosahedral symmetry of fullerene ions and also because of the many potential uses of materials containing these ions. We conclude by outlining experiments that should be capable of measuring pseudorotation in C 60 anions.

  6. Integer programming, fullerenes and nanotubes

    SciTech Connect

    Fowler, P.W.; Hansen, P.; Leroy, C.; Sachs, H.

    1994-12-31

    Graph theoretic and integer programming techniques provide answers to a series of questions in organic chemistry. We focus on problems on fullerenes, or closed carbon-cage molecules with large number of carbon atoms, and nanotubes, which are similar open or closed end tubes of carbon atoms with a few manometer diameter. These problems include isomer enumeration, counting Kekul{acute e} structures (or perfect matchings), finding Kekul{acute e} structures with a maximum number of resonant hexagons (i.e., determining the Clar and Fries numbers) and finding the stability number of fullerenes.

  7. Fullerene-porphyrin supramolecular nanocables

    NASA Astrophysics Data System (ADS)

    Buldum, A.; Reneker, D. H.

    2014-06-01

    Novel fullerene-porphyrin supramolecular nanocables were designed and their electronic properties were studied using computational modeling and first-principles density functional theory. It is demonstrated that two well-defined fullerene-porphyrin nanocables have clear channels for charge transport by electrons and holes. These two interesting nanocables have zigzag or helical chains of {{{\\rm{C}}}_{60}} molecules around a ?-stacked porphyrin core. They also have frontier electronic states which are spatially extended along the axes of the nanocables. Ballistic electronic transport is possible for ultrafast transfer of electrons along {{{\\rm{C}}}_{60}} chains. We believe these supramolecular nanocables can play important roles in molecular electronics, optoelectronics and photovoltaics.

  8. The story of making fullerenes.

    PubMed

    Krtschmer, Wolfgang

    2011-06-01

    Carbon is the most abundant condensable element in space. Our attempts to produce interstellar-like graphitic grains unexpectedly led to the discovery of a method for fullerene production in bulk amounts. These works opened the door for an entirely new branch of materials research and carbon chemistry. Here I present the various phases and steps of our work which, with interludes, lasted from 1983 to 1990. The starting point was the discovery of unexplained UV absorptions in the soot samples we had produced, while the endpoint was marked by the extraction of fullerenes in crystalline form from just these samples. PMID:21327257

  9. Sputtering Yields for C60 and Au3 Bombardment of Water Ice as a Function of Incident Kinetic Energy

    PubMed Central

    Russo, Michael F.; Szakal, Christopher; Kozole, Joseph; Winograd, Nicholas; Garrison, Barbara J.

    2008-01-01

    The total sputtering yields for water ice due to kiloelectronvolt cluster bombardment have been measured and compared to the predictions made by the mesoscale energy deposition footprint (MEDF) model. For C60 bombardment the experimental yield varies almost linearly from 820 water molecule equivalents at an incident kinetic energy of 10 keV to 10100 water molecule equivalents at a kinetic energy of 120 keV. For Au3 bombardment the experimental yield varies almost linearly from 630 water molecule equivalents at an incident energy of 10 keV and rises to 1200 water molecule equivalents at 25 keV. The MEDF model is used to calculate relative yield trends with respect to incident energy using short time molecular dynamics simulations. The results of these calculations indicate that the model can effectively predict the yield trends observed for these two clusters in experiments, although there is a consistent overestimate of the predicted induced C60 yield. It is hypothesized that this overestimate can be explained by the absence of reactions and ionization processes in the current simulations. Despite this omission experimental yield trends can be accurately predicted using relatively small amounts of computer time. The success of the model in predicting the yield of water from ice films using a variety of energies and projectiles suggests this approach may greatly aid in the optimization of experimental configurations. PMID:17503768

  10. Neutral copper cluster sputtering yields: Ne{sup +}, Ar{sup +} and Xe{sup +} bombardment

    SciTech Connect

    Coon, S.R.; Calaway, W.F.; Pellin, M.J.

    1993-08-01

    The sputtering of neutral metal clusters was investigated by measuring relative sputtering yields of copper clusters ejected from polycrystalline copper under 3.9 keV bombardment by Ne{sup +}, Ar{sup +} and Xe{sup +} ions at normal incidence. Yields of clusters from Ne{sup +} bombardment were lower than those from Ar{sup +} bombardment, were lower than from Xe{sup +} bombardment. Sputtering yield ratios Ne{sup +}/Ar{sup +} and Xe{sup +}/Ar{sup +} were 0.56 and 1.08. Size distribution of sputtered clusters can be fit by a power law dependence with exponents of {minus}8.1, {minus}8.2 and {minus}6.2 for Ne{sup +}, Ar{sup +} and Xe{sup +}, respectively. The similarity of the exponents of the Ne{sup +} and Ar{sup +} power law fits indicates that the sputtering yields for these two primary ions are similar while that for Xe{sup +} is substantially higher, in contrast to the sputtering yield ratio data. The difference between the two measurements can be explained by assuming a systematic uncertainty in the sputtering yield ratio measurements that makes the measured ratios lower than the true values. Assuming a value at the high end of the experimental Ne{sup +} sputtering yield range, the exponents of the power law fits exhibit a linear dependence on the total sputtering yield.

  11. Inorganic Fullerenes, Onions, and Tubes

    ERIC Educational Resources Information Center

    York, Andrew P. E.

    2004-01-01

    Buckminsterfullerene, which is in the shape of a soccer-ball was first discovered in 1985, has many applications as a good lubricant, or as a new superconductor. The synthesis of these inorganic fullerenes involves a great deal of interdisciplinary research between physicists, material scientists, engineers and chemists from various fields.

  12. Development of Mass Spectrometric Ionization Methods for Fullerenes and Fullerene Derivatives

    EPA Science Inventory

    Currently investigations into the environmental behavior of fullerenes and fullerene derivatives is hampered by the lack of well characterized standards and by the lack of readily available quantitative analytical methods. Reported herein are investigations into the utility of ma...

  13. Low-energy ion beam bombardment effect on the plant-cell-envelope mimetic membrane for DNA transfer

    NASA Astrophysics Data System (ADS)

    Prakrajang, K.; Sangwijit, K.; Anuntalabhochai, S.; Wanichapichart, P.; Yu, L. D.

    2012-09-01

    This study is a systematic analysis of the mechanisms involved in ion-beam induced DNA transfer, an important application of ion beam biotechnology. Cellulose membranes were used to mimic the plant cell envelope. Ion beams of argon (Ar) or nitrogen (N) at an energy of 25 keV bombarded the cellulose membranes at fluences ranging from 1015 to 1016 ions/cm2. The damage to the ion-beam-bombarded membranes was characterized using infrared spectroscopy, a micro tensile test and scanning electron microscopy (SEM). Chain scission was the dominant radiation damage type in the membrane. DNA diffusion across the membrane was significantly increased after ion beam bombardment. The increase in DNA transfer is therefore attributed to chain scission, which increases the permeability by increasing the number of pores in the membrane.

  14. Vesta, Ceres and the Jovian Early Bombardment

    NASA Astrophysics Data System (ADS)

    Turrini, D.; Coradini, A.; Magni, G.

    2011-10-01

    Vesta and Ceres are among the oldest objects that formed in the Solar System, likely predating the formation of the giant planets. Through their histories, the surfaces of the two targets of the Dawn mission would have suffered several periods of intense bombardment which shaped their present morphologies. Here we report the results of our investigation of the collisional histories of Vesta and Ceres at the time of the formation of Jupiter. The formation of the giant planet caused in fact an intense early bombardment in the asteroid belt. In those scenarios where they survived, both asteroids had their surfaces saturated by craters as big as 150 km and a few as big as 200 - 300 km. In the case of Vesta, such Jovian early bombardment would have significantly eroded the crust, likely exposing the upper mantle or causing effusive phenomena similar to lunar maria.

  15. Ion bombardment and disorder in amorphous silicon

    SciTech Connect

    Sidhu, L.S.; Gaspari, F.; Zukotynski, S.

    1997-07-01

    The effect of ion bombardment during growth on the structural and optical properties of amorphous silicon are presented. Two series of films were deposited under electrically grounded and positively biased substrate conditions. The biased samples displayed lower growth rates and increased hydrogen content relative to grounded counterparts. The film structure was examined using Raman spectroscopy. The transverse optic like phonon band position was used as a parameter to characterize network order. Biased samples displayed an increased order of the amorphous network relative to grounded samples. Furthermore, biased samples exhibited a larger optical gap. These results are correlated and attributed to reduced ion bombardment effects.

  16. Synthesis, properties and transformations of fullerene peroxides

    NASA Astrophysics Data System (ADS)

    Bulgakov, R. G.; Galimov, D. I.; Dzhemilev, U. M.

    2014-08-01

    Methods of synthesis, properties and transformations of fullerene peroxides are considered and systematized for the first time. It is shown that the chemistry of fullerene peroxides is a new approach to functionalization of fullerenes, which has been intensively developing since 2002. Methods of synthesis, mechanisms of formation and reactions of C60 and C70 alkyl peroxides with or without epoxide moieties are discussed. Transformations of fullerene peroxides affording a wide range of fullerene derivatives containing, as addends, halogen or sulfur atoms; epoxide, dioxolane, thiirane, crown ether, aziridine and dioxetane rings, as well as hydroxyl, alkoxyl and carbonyl groups, are considered. Special attention is focused on reactions constituting the basis of a new approach — so-called molecular surgery, which enables the synthesis of open-cage fullerene derivatives. It has been demonstrated that such compounds are good candidates for designing photovoltaic cells and carriers of drugs and radionuclides (for radiopharmaceuticals). The bibliography includes 130 references.

  17. Application of fullerenes in nanomedicine: an update.

    PubMed

    Dellinger, Anthony; Zhou, Zhiguo; Connor, James; Madhankumar, A B; Pamujula, Sarala; Sayes, Christie M; Kepley, Christopher L

    2013-07-01

    Fullerenes are carbon spheres presently being pursued globally for a wide range of applications in nanomedicine. These molecules have unique electronic properties that make them attractive candidates for diagnostic, therapeutic and theranostic applications. Herein, the latest research is discussed on developing fullerene-based therapeutics as antioxidants for inflammatory diseases, their potential as antiviral/bacterial agents, utility as a drug delivery device and the promise of endohedral fullerenes as new MRI contrast agents. The recent discovery that certain fullerene derivatives can stabilize immune effector cells to prevent or inhibit the release of proinflammatory mediators makes them potential candidates for several diseases such as asthma, arthritis and multiple sclerosis. Gadolinium-containing endohedral fullerenes are being pursued as diagnostic MRI contrast agents for several diseases. Finally, a new class of fullerene-based theranostics has been developed, which combine therapeutic and diagnostic capabilities to specifically detect and kill cancer cells. PMID:23837857

  18. Emission of excited particles ejected from the surface of a copper target during ion bombardment

    SciTech Connect

    Gritsyna, V.V.; Koval`, A.G.; Koppe, V.T.

    1995-02-01

    Various ways of presenting experimental data for describing the dependence of the excited state population of the excitation energy during ion bombardment of solids are analyzed, and the most correct way of presenting the data is indicated. Major characteristics of ion-induced photon emission during Ar{sup +} bombardment (20 keV) of a copper target are presented. It is shown that each incident ion ejects 2x10{sup -4} excited copper atoms with E{sub kin}{ge} 1 keV because the energy levels of the excited states are located in the free part of the conduction band of copper and, therefore, the probability R({infinity}) for a particle escaping from the surface to preserve the excited state depends substantially on its velocity (or E{sub kin}): R({infinity}) is 0.73 for E{sub kin} = 1.4 keV, and 0.04 for E{sub kin}=14 eV. Experimental exponential dependence of the excitation efficiency on the excitation energy is treated assuming statistical distribution of inelastic energy among various states of the decomposing excited complex formed during interaction of Ar{sup +} with the surface of a solid. 21 refs., 3 figs., 2 tabs.

  19. Aspects of organic chemistry of fullerenes

    NASA Astrophysics Data System (ADS)

    Hirsch, Andreas

    1997-11-01

    Successive additions to [60]fullerene show a remarkable degree of regioselectivity. Two characteristic examples of additions, namely nucleophilic cyclopropanations of 6-6 double bonds as well as formations of 5 6 bridged open azafulleroids, have been systematically investigated by analytical, spectroscopic as well as by computational methods. Regioselective additions to activated positions within the carbon framework of fullerene derivatives are the key steps for both controlled ring opening of the fullerene core and the synthesis of heterofullerenes.

  20. C(240)-----The most Chemically Inert Fullerene?

    NASA Technical Reports Server (NTRS)

    Haddon, R. C.; Scuseria, G. E.; Smalley, R. E.

    1997-01-01

    The reactivity of the fullerenes is primarily a function of their strain, as measured by the pyramidalization angle or curvature of the conjugated carbon atoms. The development of faceting in the structure of large icosahedral fullerenes leads to a minimum in the value of the maximum fullerene pyramidalization angle that lies in the vicinity of C-240. On this basis it is argued that C-240 will be the most chemically inert fullerene. This observation explains the production of [10,10] single-walled nanotubes because a C-240 hemisphere is required for the nucleation of such tubes.

  1. Hamilton cycles and paths in fullerenes.

    PubMed

    Marusic, Dragan

    2007-01-01

    It has been conjectured that every fullerene, that is, every skeleton of a spherical trivalent graph whose set of faces consists of pentagons and hexagons alone, is Hamiltonian. In this article the validity of this conjecture is explored for the class of leapfrog-fullerenes. It is shown that, given an arbitrary fullerene F, the corresponding leapfrog-fullerene Le(F) contains a Hamilton cycle if the number of vertices of F is congruent to 2 modulo 4 and contains a long cycle missing out only two adjacent vertices, and thus also a Hamilton path, if the number of vertices of F is divisible by 4. PMID:17488067

  2. Toxicological Effects of Fullerenes on Caenorhabditis elegans

    NASA Astrophysics Data System (ADS)

    Schomaker, Justin; Snook, Renee; Howell, Carina

    2014-03-01

    The nematode species Caenorhabditis elegans is a useful genetic model organism due to its simplicity and the substantial molecular, genetic, and developmental knowledge about the species. In this study, this species was used to test the toxicological effects of C60 fullerene nanoparticles. In previous studies using rats, a solution of C60 fullerenes in olive oil proved to extend the life of the subjects. The purpose of this experiment was to subject C. elegans to varying concentrations of C60 fullerenes and observe their toxicological effects. Initial findings indicate a link between fullerene exposure and enlargement of the vulva as well as the formation of a small nodule at the base of the tail in some individuals. While the fullerenes are not lethally toxic in C. elegans, results will be presented that pertain to changes in life span and progeny of the nematodes exposed to varying concentrations of fullerenes as well as the mechanisms of toxicity. High magnification imaging via SEM and/or AFM will be used to characterize the fullerene nanoparticles. Testing the toxicity of fullerenes in a wide variety of organisms will lead to a more complete understanding of the effects of fullerenes on living organisms to ultimately understand their effects in humans. This work was supported by National Science Foundation grants DUE-1058829, DMR-0923047, DUE-0806660 and Lock Haven FPDC grants.

  3. Development of Advanced Alloys using Fullerenes

    NASA Technical Reports Server (NTRS)

    Sims, J.; Wasz, M.; O'Brien, J.; Callahan, D. L.; Barrera, E. V.

    1994-01-01

    Development of advanced alloys using fullerenes is currently underway to produce materials for use in the extravehicular mobility unit (EMU). These materials will be directed toward commercial usages as they are continually developed. Fullerenes (of which the most common is C(sub 60)) are lightweight, nanometer size, hollow molecules of carbon which can be dispersed in conventional alloy systems to enhance strength and reduce weight. In this research, fullerene interaction with aluminum is investigated and a fullerene-reinforced aluminum alloy is being developed for possible use on the EMU. The samples were manufactured using standard commercial approaches including powder metallurgy and casting. Alloys have been processed having 1.3, 4.0 and 8.0 volume fractions of fullerenes. It has been observed that fullerene dispersion is related to the processing approach and that they are stable for the processing conditions used in this research. Emphasis will be given to differential thermal analysis and wavelength dispersive analysis of the processed alloys. These two techniques are particularly useful in determining the condition of the fullerenes during and after processing. Some discussion will be given as to electrical properties of fullerene-reinforced materials. Although the aluminum and other advanced alloys with fullerenes are being developed for NASA and the EMU, the properties of these materials will be of interest for commercial applications where specific Dual-Use will be given.

  4. Stability of extreme ultraviolet multilayer coatings to low energy proton bombardment.

    PubMed

    Pelizzo, M G; Corso, Alain Jody; Zuppella, Paola; Windt, D L; Mattei, G; Nicolosi, P

    2011-08-01

    In this work we present results of an new experiment related to low energy protons bombardments on nano-structured optical coatings. Multilayer structures protected by different capping layers have been fabricated and exposed to low energy protons (1 keV). The experimental parameters have been selected considering the potential application of the coatings to solar mission instrumentation. Future solar missions will investigate the Sun from very close distances and optical components are constantly exposed to low energy ion particles irradiation. The experiment was repeated fixing the proton flux while varying the total dose accumulated. Results show that physical processes occurred at the uppermost interfaces can strongly damage the structure. PMID:21934844

  5. Mesoscale energy deposition footprint model for kiloelectronvolt cluster bombardment of solids.

    PubMed

    Russo, Michael F; Garrison, Barbara J

    2006-10-15

    Molecular dynamics simulations have been performed to model 5-keV C60 and Au3 projectile bombardment of an amorphous water substrate. The goal is to obtain detailed insights into the dynamics of motion in order to develop a straightforward and less computationally demanding model of the process of ejection. The molecular dynamics results provide the basis for the mesoscale energy deposition footprint model. This model provides a method for predicting relative yields based on information from less than 1 ps of simulation time. PMID:17037922

  6. Extraterrestrial Helium (He@C60) Trapped in Fullerenes in the Sudbury Impact Structure

    NASA Technical Reports Server (NTRS)

    Becker, L.; Bada, J. L.; Poreda, R. J.; Bunch, T. E.

    1997-01-01

    Fullerenes (C60 and C70) have recently been identified in a shock-produced breccia (Onaping Formation) associated with the 1.85-Ga Sudbury Impact Crater. The presence of parts-per-million levels of fullerenes in this impact structure raises interesting questions about the processes that led to the formation of fullerenes and the potential for delivery of intact organic material to the Earth by a large bolide (e.g., asteroid or comet). Two possible scenarios for the presence of fullerenes in the Sudbury impact deposits are that (1) fullerenes are synthesized within the impact plume from the C contained in the bolide; or (2) fullerenes are already present in the bolide and survived the impact event. The correlation of C and trapped noble gas atoms in meteorites is well established. Primitive meteorites contain several trapped noble gas components that have anomalous isotopic compositions, some of which may have a presolar origin. Several C-bearing phases, including SiC, graphite, and diamond, have been recognized as carriers of trapped noble gases. It has also been suggested that fullerenes (C60 and C70) might be a carrier of noble gas components in carbonaceous chondrites. Recently, fullerenes have been detected in separate samples in the Allende meteorite. Carbon-60 is large enough to enclose the noble gases He, Ne, Ar, Kr, and Xe, but it is too small to contain diatomic gases such as N2 or triatomic gases such as CO2. Recent experimental work has demonstrated that noble gases of a specific isotopic composition can be introduced into synthetic fullerenes at high temperatures and pressures; these encapsulated gases can then be released by the breaking of one or more C bonds during step-heating under vacuum. These thermal-release patterns for He encapsulated within the C60 molecule (He@C60) are similar to the patterns for acid residues of carbonaceous chondrites, suggesting that fullerenes could be an additional carrier of trapped noble gases in acid residues of meteorites. Analysis and Results: In order to characterize the noble gas compositions of the Sudbury fullerenes, we undertook a systematic study of acid-resistant residues throughout the C-rich layer (Black member) of the Onaping Formation. Samples were demineralized and extracted using standard techniques. The Onaping extracts were analyzed using several techniques, including UV-Vis adsorption, electro spray mass spectrometry, and laser desorption (linear and reflectron) time-of-flight (TOF) mass spectrometry (LDMS). The Sudbury fullerenes were then separated and purified using HPLC coupled with a photo diode array detector. The HPLC extracts containing the purified fullerenes were loaded into a metal tube furnace within a glove box under a N atmosphere in preparation for noble gas analyses. The 3-He and 4-He content of the fullerene extracts was measured using previously reported standard techniques . Discussion: Fullerenes (C60 and C70) in the Sudbury Impact Structure have been found to contain trapped He with a 3-He/4-He ratio greater than 5 x 10(exp -4). The 3-He/4-He ratio exceeds the accepted solar value by more than 30% and is more than 10x higher than the maximum reported mantle value. Terrestrial nuclear reactions or cosmic-my bombardment are not sufficient to generate such a high ratio. The 3-He/4-He ratios in the Sudbury fullerenes are similar to those determined for interplanetary dust particles. The greater-than-solar ratios of 3-He/4-He in the Sudbury fullerenes may indicate a presolar origin, although alternative mechanisms occurring in the ISM to explain these high ratios (e.g., spallation reactions, selective He implantation, etc.) cannot be entirely ruled out. We are currently attempting to isolate enough fullerene material to measure anomalous Ne (or Kr or Xe) contained within the C60 (e.g., the "pure" 22-Ne component) and thus determine whether the Sudbury fullerenes are indeed presolar in origin.

  7. Fullerenes generated from porous structures.

    PubMed

    Paupitz, Ricardo; Junkermeier, Chad E; van Duin, Adri C T; Branicio, Paulo S

    2014-12-14

    A class of macromolecules based on the architecture of the well-known fullerenes is theoretically investigated. The building blocks used to geometrically construct these molecules are the two dimensional structures: porous graphene and biphenylene-carbon. Density functional-based tight binding methods as well as reactive molecular dynamics methods are applied to study the electronic and structural properties of these molecules. Our calculations predict that these structures can be stable up to temperatures of 2500 K. The atomization energies of carbon structures are predicted to be in the range of 0.45 eV per atom to 12.11 eV per atom (values relative to the C60 fullerene), while the hexagonal boron nitride analogues have atomization energies between -0.17 eV per atom and 12.01 eV per atom (compared to the B12N12 fullerene). Due to their high porosity, these structures may be good candidates for gas storage and/or molecular encapsulation. PMID:25347301

  8. The quest for inorganic fullerenes

    NASA Astrophysics Data System (ADS)

    Pietsch, Susanne; Dollinger, Andreas; Strobel, Christoph H.; Park, Eun Ji; Gantefr, Gerd; Seo, Hyun Ook; Kim, Young Dok; Idrobo, Juan-Carlos; Pennycook, Stephen J.

    2015-10-01

    Experimental results of the search for inorganic fullerenes are presented. MonSm- and WnSm- clusters are generated with a pulsed arc cluster ion source equipped with an annealing stage. This is known to enhance fullerene formation in the case of carbon. Analogous to carbon, the mass spectra of the metal chalcogenide clusters produced in this way exhibit a bimodal structure. The species in the first maximum at low mass are known to be platelets. Here, the structure of the species in the second maximum is studied by anion photoelectron spectroscopy, scanning transmission electron microscopy, and scanning tunneling microcopy. All experimental results indicate a two-dimensional structure of these species and disagree with a three-dimensional fullerene-like geometry. A possible explanation for this preference of two-dimensional structures is the ability of a two-element material to saturate the dangling bonds at the edges of a platelet by excess atoms of one element. A platelet consisting of a single element only cannot do this. Accordingly, graphite and boron might be the only materials forming nano-spheres because they are the only single element materials assuming two-dimensional structures.

  9. Functionalized fullerenes in photodynamic therapy.

    PubMed

    Huang, Ying-Ying; Sharma, Sulbha K; Yin, Rui; Agrawal, Tanupriya; Chiang, Long Y; Hamblin, Michael R

    2014-09-01

    Since the discovery of C60 fullerene in 1985, scientists have been searching for biomedical applications of this most fascinating of molecules. The unique photophysical and photochemical properties of C60 suggested that the molecule would function well as a photosensitizer in photodynamic therapy (PDT). PDT uses the combination of non-toxic dyes and harmless visible light to produce reactive oxygen species that kill unwanted cells. However the extreme insolubility and hydrophobicity of pristine CO60, mandated that the cage be functionalized with chemical groups that provided water solubility and biological targeting ability. It has been found that cationic quaternary ammonium groups provide both these features, and this review covers work on the use of cationic fullerenes to mediate destruction of cancer cells and pathogenic microorganisms in vitro and describes the treatment of tumors and microbial infections in mouse models. The design, synthesis, and use of simple pyrrolidinium salts, more complex decacationic chains, and light-harvesting antennae that can be attached to C60, C70 and C84 cages are covered. In the case of bacterial wound infections mice can be saved from certain death by fullerene-mediated PDT. PMID:25544837

  10. Functionalized Fullerenes in Photodynamic Therapy

    PubMed Central

    Huang, Ying-Ying; Sharma, Sulbha K.; Yin, Rui; Agrawal, Tanupriya; Chiang, Long Y.; Hamblin, Michael R.

    2014-01-01

    Since the discovery of C60 fullerene in 1985, scientists have been searching for biomedical applications of this most fascinating of molecules. The unique photophysical and photochemical properties of C60 suggested that the molecule would function well as a photosensitizer in photodynamic therapy (PDT). PDT uses the combination of non-toxic dyes and harmless visible light to produce reactive oxygen species that kill unwanted cells. However the extreme insolubility and hydrophobicity of pristine C60, mandated that the cage be functionalized with chemical groups that provided water solubility and biological targeting ability. It has been found that cationic quaternary ammonium groups provide both these features, and this review covers work on the use of cationic fullerenes to mediate destruction of cancer cells and pathogenic microorganisms in vitro and describes the treatment of tumors and microbial infections in mouse models. The design, synthesis, and use of simple pyrrolidinium salts, more complex decacationic chains, and light-harvesting antennae that can be attached to C60, C70 and C84 cages are covered. In the case of bacterial wound infections mice can be saved from certain death by fullerene-mediated PDT. PMID:25544837

  11. Ion-chain interaction in keV ion-beam-irradiated polystyrene

    SciTech Connect

    Calcagno, L.; Foti, G.; Licciardello, A.; Puglisi, O.

    1987-09-21

    Molecular weight distribution has been measured in monodisperse polystyrene film (MW = 9 000 amu) after ion bombardment, in the ion fluence range 10/sup 11/--10/sup 13/ ions/cm/sup 2/. The chosen beams are 100 keV He, 200 keV Ne, and 400 keV Ar. The experimental data have been interpreted in terms of a simple statistical model for cross-links. The chemical yield is found to be very high and equal to 0.30, about a factor of 10 higher than the values given in the literature for gamma irradiation (M. Dole, in The Radiation Chemistry of Macromolecules (Academic, New York, 1973), Vol. 2, Chap. 5, p. 57).

  12. Simulation of ion beam bombardment using Bayfol CR 6-2

    NASA Astrophysics Data System (ADS)

    Radwan, S. I.; Shehata, M. M.; El-Khabeary, H.; Helal, A. G.

    2016-04-01

    In this work, the simulation of ion beam bombardment in Bayfol CR 6-2 polymer at energies varies from 5 keV to 45 keV was determined. The simulation process was made by multiply charged copper and lead ions of different incident angles. The open source computer code SRIM 3D was used for the simulation to determine the ion beam penetrability into the Bayfol CR 6-2 specimens. The range, recoil distribution and total damage of copper and lead ions using Bayfol 6-2 specimens at different energies and incident angles were studied. It was found that the ion range, recoil distribution and total damage at different incident angles on Bayfol 6-2 specimens increases by increasing the ions energy using copper and lead ions respectively.

  13. Nanocone formation on ion-bombarded InP surfaces

    NASA Astrophysics Data System (ADS)

    Kramczynski, Detlef; Gnaser, Hubert

    2015-11-01

    Surfaces of InP(1 0 0) were bombarded by 2.1 keV Ar+ ions under normal incidence. The total accumulated ion fluence the samples were exposed to was varied roughly from 1 1017 cm-2 to 3 1018 cm-2 while ion fluxes in the range of (0.1-2) 1014 cm-2 s-1 were used. The surface morphology resulting from these ion irradiations was examined by scanning electron microscopy (SEM). For a specific range of ion fluxes and fluences, regular closely-spaced nanocone arrays are found to form, with the cones having typical base diameters of about 100 nm. Around their outer peripheries, they commonly exhibit rather distinct protrusions, an observation not reported in previous investigations. The inspection of the initial stages of nanocone formation indicates that the growth of adatom islands, first on the pristine surface and later on previously formed islands, may lead to these 3D nanostructures. This finding would imply that surface diffusion processes of adatoms constitute an important mechanism in the evolution of the observed topography.

  14. Fullerenic structures and such structures tethered to carbon materials

    DOEpatents

    Goel, Anish; Howard, Jack B.; Vander Sande, John B.

    2012-10-09

    The fullerenic structures include fullerenes having molecular weights less than that of C.sub.60 with the exception of C.sub.36 and fullerenes having molecular weights greater than C.sub.60. Examples include fullerenes C.sub.50, C.sub.58, C.sub.130, and C.sub.176. Fullerenic structure chemically bonded to a carbon surface is also disclosed along with a method for tethering fullerenes to a carbon material. The method includes adding functionalized fullerene to a liquid suspension containing carbon material, drying the suspension to produce a powder, and heat treating the powder.

  15. Fullerenic structures and such structures tethered to carbon materials

    DOEpatents

    Goel, Anish; Howard, Jack B.; Vander Sande, John B.

    2010-01-05

    The fullerenic structures include fullerenes having molecular weights less than that of C.sub.60 with the exception of C.sub.36 and fullerenes having molecular weights greater than C.sub.60. Examples include fullerenes C.sub.50, C.sub.58, C.sub.130, and C.sub.176. Fullerenic structure chemically bonded to a carbon surface is also disclosed along with a method for tethering fullerenes to a carbon material. The method includes adding functionalized fullerene to a liquid suspension containing carbon material, drying the suspension to produce a powder, and heat treating the powder.

  16. Gas storage using fullerene based adsorbents

    NASA Technical Reports Server (NTRS)

    Loutfy, Raouf O. (Inventor); Lu, Xiao-Chun (Inventor); Li, Weijiong (Inventor); Mikhael, Michael G. (Inventor)

    2000-01-01

    This invention is directed to the synthesis of high bulk density high gas absorption capacity adsorbents for gas storage applications. Specifically, this invention is concerned with novel gas absorbents with high gravimetric and volumetric gas adsorption capacities which are made from fullerene-based materials. By pressing fullerene powder into pellet form using a conventional press, then polymerizing it by subjecting the fullerene to high temperature and high inert gas pressure, the resulting fullerene-based materials have high bulk densities and high gas adsorption capacities. By pre-chemical modification or post-polymerization activation processes, the gas adsorption capacities of the fullerene-based adsorbents can be further enhanced. These materials are suitable for low pressure gas storage applications, such as oxygen storage for home oxygen therapy uses or on-board vehicle natural gas storage. They are also suitable for storing gases and vapors such as hydrogen, nitrogen, carbon dioxide, and water vapor.

  17. Inhibition of Inflammatory Arthritis Using Fullerene Nanomaterials

    PubMed Central

    Dellinger, Anthony L.; Cunin, Pierre; Lee, David; Kung, Andrew L.; Brooks, D. Bradford; Zhou, Zhiguo; Nigrovic, Peter A.; Kepley, Christopher L.

    2015-01-01

    Inflammatory arthritis (e.g. rheumatoid arthritis; RA) is a complex disease driven by the interplay of multiple cellular lineages. Fullerene derivatives have previously been shown to have anti-inflammatory capabilities mediated, in part, by their ability to prevent inflammatory mediator release by mast cells (MC). Recognizing that MC can serve as a cellular link between autoantibodies, soluble mediators, and other effector populations in inflammatory arthritis, it was hypothesized that fullerene derivatives might be used to target this inflammatory disease. A panel of fullerene derivatives was tested for their ability to affect the function of human skin-derived MC as well as other lineages implicated in arthritis, synovial fibroblasts and osteoclasts. It is shown that certain fullerene derivatives blocked Fc?R- and TNF-?-induced mediator release from MC; TNF-?-induced mediator release from RA synovial fibroblasts; and maturation of human osteoclasts. MC inhibition by fullerene derivatives was mediated through the reduction of mitochondrial membrane potential and Fc?R-mediated increases in cellular reactive oxygen species and NF-?B activation. Based on these in vitro data, two fullerene derivatives (ALM and TGA) were selected for in vivo studies using K/BxN serum transfer arthritis in C57BL/6 mice and collagen-induced arthritis (CIA) in DBA/1 mice. Dye-conjugated fullerenes confirmed localization to affected joints in arthritic animals but not in healthy controls. In the K/BxN moldel, fullerenes attenuated arthritis, an effect accompanied by reduced histologic inflammation, cartilage/bone erosion, and serum levels of TNF-?. Fullerenes remained capable of attenuating K/BxN arthritis in mast cell-deficient mice Cre-Master mice, suggesting that lineages beyond the MC represent relevant targets in this system. These studies suggest that fullerene derivatives may hold promise both as an assessment tool and as anti-inflammatory therapy of arthritis. PMID:25879437

  18. Production of Endohedral Fullerenes by Ion Implantation

    SciTech Connect

    Diener, M.D.; Alford, J. M.; Mirzadeh, S.

    2007-05-31

    The empty interior cavity of fullerenes has long been touted for containment of radionuclides during in vivo transport, during radioimmunotherapy (RIT) and radioimaging for example. As the chemistry required to open a hole in fullerene is complex and exceedingly unlikely to occur in vivo, and conformational stability of the fullerene cage is absolute, atoms trapped within fullerenes can only be released during extremely energetic events. Encapsulating radionuclides in fullerenes could therefore potentially eliminate undesired toxicity resulting from leakage and catabolism of radionuclides administered with other techniques. At the start of this project however, methods for production of transition metal and p-electron metal endohedral fullerenes were completely unknown, and only one method for production of endohedral radiofullerenes was known. They therefore investigated three different methods for the production of therapeutically useful endohedral metallofullerenes: (1) implantation of ions using the high intensity ion beam at the Oak Ridge National Laboratory (ORNL) Surface Modification and Characterization Research Center (SMAC) and fullerenes as the target; (2) implantation of ions using the recoil energy following alpha decay; and (3) implantation of ions using the recoil energy following neutron capture, using ORNL's High Flux Isotope Reactor (HFIR) as a thermal neutron source. While they were unable to obtain evidence of successful implantation using the ion beam at SMAC, recoil following alpha decay and neutron capture were both found to be economically viable methods for the production of therapeutically useful radiofullerenes. In this report, the procedures for preparing fullerenes containing the isotopes {sup 212}Pb, {sup 212}Bi, {sup 213}Bi, and {sup 177}Lu are described. None of these endohedral fullerenes had ever previously been prepared, and all of these radioisotopes are actively under investigation for RIT. Additionally, the chemistry for derivatizing the radiofullerenes for water-solubility and a method for removing exohedral radionuclides are reported. The methods and chemistry developed during this CRADA are the crucial first steps for the development of fullerenes as a method superior to existing technologies for in vivo transport of radionuclides.

  19. Biomolecular Emission by Swift Heavy Ion Bombardment

    NASA Astrophysics Data System (ADS)

    Wakamatsu, Yoshinobu; Yamada, Hideaki; Ninomiya, Satoshi; Jones, Brian N.; Seki, Toshio; Aoki, Takaaki; Webb, Roger; Matsuo, Jiro

    2011-01-01

    Secondary Ion Mass spectrometry (SIMS) has been generally used in the field of material sciences. In recent years, it has also been applied for molecular imaging of biological samples. Nevertheless, molecular ions derived from the large molecules (more than 1 kDa) were detected with very low sensitivity. Plasma desorption mass spectrometry (PDMS) is known as mass spectrometry for large organic molecule. In PDMS, fission fragments bombard samples and the impact induces molecular ionization by electronic excitation. Large organic molecules are detected by using swift heavy ions in SIMS. In this work, 6 MeV Cu4+ we irradiated angiotensin II, a class of peptides. The intact molecular ions generated by swift heavy ion irradiation were analyzed by time-of-flight (TOF) measurement. The yields are compared with some other probe ions, bismuth or flurane. Swift heavy ion bombardment ionized large organic molecules more effectively than other probes. Therefore, high energy ion can be applied in high resolution molecular imaging.

  20. Cathode Ion Bombardment in RF Photoguns

    SciTech Connect

    Pozdeyev,E.; Kayran, D.; Litvinenko, V.

    2008-09-01

    In this paper, we use the method of rapid oscillating field to solve the equation of ion motion in an RF gun. We apply the method to the BNL 1/2-cell SRF photogun and demonstrate that a significant portion of ions produced in the gun can reach the cathode if no special precautions are taken. Also, the paper proposes a simple mitigation recipe that can reduce the rate of ion bombardment.

  1. Machine Phase Fullerene Nanotechnology: 1996

    NASA Technical Reports Server (NTRS)

    Globus, Al; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    NASA has used exotic materials for spacecraft and experimental aircraft to good effect for many decades. In spite of many advances, transportation to space still costs about $10,000 per pound. Drexler has proposed a hypothetical nanotechnology based on diamond and investigated the properties of such molecular systems. These studies and others suggest enormous potential for aerospace systems. Unfortunately, methods to realize diamonoid nanotechnology are at best highly speculative. Recent computational efforts at NASA Ames Research Center and computation and experiment elsewhere suggest that a nanotechnology of machine phase functionalized fullerenes may be synthetically relatively accessible and of great aerospace interest. Machine phase materials are (hypothetical) materials consisting entirely or in large part of microscopic machines. In a sense, most living matter fits this definition. To begin investigation of fullerene nanotechnology, we used molecular dynamics to study the properties of carbon nanotube based gears and gear/shaft configurations. Experiments on C60 and quantum calculations suggest that benzyne may react with carbon nanotubes to form gear teeth. Han has computationally demonstrated that molecular gears fashioned from (14,0) single-walled carbon nanotubes and benzyne teeth should operate well at 50-100 gigahertz. Results suggest that rotation can be converted to rotating or linear motion, and linear motion may be converted into rotation. Preliminary results suggest that these mechanical systems can be cooled by a helium atmosphere. Furthermore, Deepak has successfully simulated using helical electric fields generated by a laser to power fullerene gears once a positive and negative charge have been added to form a dipole. Even with mechanical motion, cooling, and power; creating a viable nanotechnology requires support structures, computer control, a system architecture, a variety of components, and some approach to manufacture. Additional information is contained within the original extended abstract.

  2. A semidynamic study of polymer surface morphology development in Kapton-H TM sputter etched by 6 keV xenon atoms

    NASA Astrophysics Data System (ADS)

    Michael, R.; Stulik, D.

    1987-09-01

    A semidynamic study of the surface morphology development on 6 keV Xenon atom bombarded polyimide (Kapton-H TM) is presented and discussed in light of present models of polymer sputtering and material surface morphology development. Using a series of particle bombardment-gold coating-SEM investigation-gold layer stripping cycles, the whole process of the surface morphology development can be studied in a greater detail. Kapton-H is extremely resistive to particle bombardment. Under high fluence particle bombardment, the surface morphology development proceeds from uniform rows of submicron protrusions to flat-top columns which later disintegrate into long thin fiberlike structures. The average sputtering yield of Kapton-H is about 30 amu/atom (i.e., 0.08 [-C 22H 10N 2O 5-] monomer units/atom). This value is very low when compared to other polymer TMtrademarks of E.I. Dupont De Nemours & Co.

  3. Ion bombardment experiments suggesting an origin for organic particles in pre-cometary and cometary ices

    NASA Technical Reports Server (NTRS)

    Wdowiak, Thomas J.; Robinson, Edward L.; Flickinger, Gregory C.; Boyd, David A.

    1989-01-01

    During the Giotto and Vega encounters with Comet Halley both organic particles called CHON and energetic ions were detected. The acceleration of ions to hundreds of keV in the vicinity of the bow shock and near the nucleus may be a demonstration of a situation occurring in the early solar system (perhaps during the T Tauri stage) that led to the formation of organic particles only now released. Utilizing a Van de Graaff accelerator and a target chamber having cryogenic and mass spectrometer capabilities, frozen gases were bombarded at 10 K with 175 keV protons with the result that fluffy solid material remains after sublimation of the ice. Initial experiments were carried out with a gas mixture in parts of 170 carbon monoxide, 170 argon, 25 water, 20 nitrogen, and 15 methane formulated to reflect an interstellar composition in experiments involving the freezing out of the products of a plasma. The plasma experiments resulted in a varnish-like film residue that exhibited luminescence when excited with ultraviolet radiation, while the ion bombardment created particulate material that was not luminescent.

  4. Biological Effects of Low Energy Ar+ Ion Bombardment on Silkworm Eggs: a Novel Animal Model

    NASA Astrophysics Data System (ADS)

    Xu, Jiaping; Wu, Yuejin; Liu, Xuelan; Yuan, Hang; Yu, Zengliang

    2009-06-01

    In this study, we found for the first time that silkworm eggs were able to survive in vacuum for a long period of time. Subsequently, low energy Ar+ ions with different energies and fluences were used to bombard silkworm eggs so as to explore the resulting biological effects. Results showed that (i) the exposure of silkworm eggs to vacuum within 10 min did not cause significant impact on the hatching rates, while the irradiation of silkworm eggs by Ar+ ions of 25 keV or 30 keV with fluences ranging from 2.62.6 1015 ion/cm2 to 82.6 1015 ion/cm2 caused a significant impact on the hatching rates, and the hatching rates decreased with the increase in the fluence and energy level; (ii) the irradiation of silkworm eggs by Ar+ ions of 30 keV with a fluence of 82.6 1015 ion/cm2 or 92.6 1015 ion/cm2 resulted in a noticeable etching on the egg shell surface which could be observed by a scanning electron microscope; and (iii) the irradiation of silkworm eggs by Ar+ ions of 30 keV with a fluence of 92.6 1015 ion/cm2 generated several mutant phenotypes which were observed in the 5th instar silkworms and a moth.

  5. Metallosupramolecular receptors for fullerene binding and release.

    PubMed

    Garca-Simn, Cristina; Costas, Miquel; Ribas, Xavi

    2015-12-22

    Fullerene extracts are easily available from fullerene soot, but finding an efficient strategy to obtain them in pure form remains elusive, especially for higher fullerenes (Cx, x > 70). The properties of the latter remain unclear and their potential application to multiple research fields has not been developed mainly due to their purification difficulties. In this Tutorial Review we cover the use of molecular receptors for the separation of fullerenes by means of host-guest interactions. This strategy allows gaining selectivity, no specialized equipment is required and, ideally, recyclable systems can be designed. We focus on the metallosupramolecular receptors using the metal-ligand coordination approach, which offers a controlled and versatile strategy to design fullerene hosts, and the latest strategies to release the fullerene guest will be described. The field is probably in its beginnings but it is rapidly evolving and we are confident that this tutorial review will help researchers to rapidly gain a general overview of the main works and concepts that are leading this promising strategy and that may lead towards a useful methodology to purify fullerenes. PMID:26456881

  6. Observation of an all-boron fullerene

    NASA Astrophysics Data System (ADS)

    Zhai, Hua-Jin; Zhao, Ya-Fan; Li, Wei-Li; Chen, Qiang; Bai, Hui; Hu, Han-Shi; Piazza, Zachary A.; Tian, Wen-Juan; Lu, Hai-Gang; Wu, Yan-Bo; Mu, Yue-Wen; Wei, Guang-Feng; Liu, Zhi-Pan; Li, Jun; Li, Si-Dian; Wang, Lai-Sheng

    2014-08-01

    After the discovery of fullerene-C60, it took almost two decades for the possibility of boron-based fullerene structures to be considered. So far, there has been no experimental evidence for these nanostructures, in spite of the progress made in theoretical investigations of their structure and bonding. Here we report the observation, by photoelectron spectroscopy, of an all-boron fullerene-like cage cluster at B40- with an extremely low electron-binding energy. Theoretical calculations show that this arises from a cage structure with a large energy gap, but that a quasi-planar isomer of B40- with two adjacent hexagonal holes is slightly more stable than the fullerene structure. In contrast, for neutral B40 the fullerene-like cage is calculated to be the most stable structure. The surface of the all-boron fullerene, bonded uniformly via delocalized ? and ? bonds, is not perfectly smooth and exhibits unusual heptagonal faces, in contrast to C60 fullerene.

  7. Observation of an all-boron fullerene.

    PubMed

    Zhai, Hua-Jin; Zhao, Ya-Fan; Li, Wei-Li; Chen, Qiang; Bai, Hui; Hu, Han-Shi; Piazza, Zachary A; Tian, Wen-Juan; Lu, Hai-Gang; Wu, Yan-Bo; Mu, Yue-Wen; Wei, Guang-Feng; Liu, Zhi-Pan; Li, Jun; Li, Si-Dian; Wang, Lai-Sheng

    2014-08-01

    After the discovery of fullerene-C60, it took almost two decades for the possibility of boron-based fullerene structures to be considered. So far, there has been no experimental evidence for these nanostructures, in spite of the progress made in theoretical investigations of their structure and bonding. Here we report the observation, by photoelectron spectroscopy, of an all-boron fullerene-like cage cluster at B40(-) with an extremely low electron-binding energy. Theoretical calculations show that this arises from a cage structure with a large energy gap, but that a quasi-planar isomer of B40(-) with two adjacent hexagonal holes is slightly more stable than the fullerene structure. In contrast, for neutral B40 the fullerene-like cage is calculated to be the most stable structure. The surface of the all-boron fullerene, bonded uniformly via delocalized ? and ? bonds, is not perfectly smooth and exhibits unusual heptagonal faces, in contrast to C60 fullerene. PMID:25054944

  8. Material and energy intensity of fullerene production.

    PubMed

    Anctil, Annick; Babbitt, Callie W; Raffaelle, Ryne P; Landi, Brian J

    2011-03-15

    Fullerenes are increasingly being used in medical, environmental, and electronic applications due to their unique structural and electronic properties. However, the energy and environmental impacts associated with their commercial-scale production have not yet been fully investigated. In this work, the life cycle embodied energy of C(60) and C(70) fullerenes has been quantified from cradle-to-gate, including the relative contributions from synthesis, separation, purification, and functionalization processes, representing a more comprehensive scope than used in previous fullerene life cycle studies. Comparison of two prevalent production methods (plasma and pyrolysis) has shown that pyrolysis of 1,4-tetrahydronaphthalene emerges as the method with the lowest embodied energy (12.7 GJ/kg of C(60)). In comparison, plasma methods require a large amount of electricity, resulting in a factor of 7-10× higher embodied energy in the fullerene product. In many practical applications, fullerenes are required at a purity >98% by weight, which necessitates multiple purification steps and increases embodied energy by at least a factor of 5, depending on the desired purity. For applications such as organic solar cells, the purified fullerenes need to be chemically modified to [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM), thus increasing the embodied energy to 64.7 GJ/kg C(60)-PCBM for the specified pyrolysis, purification, and functionalization conditions. Such synthesis and processing effects are even more significant for the embodied energy of larger fullerenes, such as C(70), which are produced in smaller quantities and are more difficult to purify. Overall, the inventory analysis shows that the embodied energy of all fullerenes are an order of magnitude higher than most bulk chemicals, and, therefore, traditional cutoff rules by weight during life cycle assessment of fullerene-based products should be avoided. PMID:21332197

  9. Chemistry, physics, and astrophysics studies of fullerenes

    SciTech Connect

    Kroto, H.W.; Prassides, K.; Stace, A.J.; Taylor, R.; Walton, D.R.M.

    1993-12-31

    Fullerene research at Sussex is directed at a wide range of chemical, physical and material science properties of these new compounds, their derivatives and their extended carbon analogues. Not only are cluster beam studies of sub-60 fullerenes being investigated but also fullerene use as synthons and their dynamical behaviour. The relation of C{sub 60} formation to carbon nucleation and the factors which govern the structure of carbon microparticles are being investigated. The discovery of C{sub 60} and the breakthrough in its extraction were both a consequence of astrophysically motivated research and the significance of C{sub 60} in space is also an area of continued study.

  10. Water-soluble fullerene derivatives for drug discovery.

    PubMed

    Nakamura, Shigeo; Mashino, Tadahiko

    2012-01-01

    Fullerenes (represented by buckminsterfullerene, C(60)) are a new kind of organic compound with a cage-like structure. A great deal of attention has been focused on their unique properties. From the viewpoint of drug discovery, fullerenes could be novel lead compounds for drug discovery. However, fullerenes are poorly soluble in aqueous media. Incorporation of water-soluble groups into the fullerene core enables investigation of its biological activities. Certain fullerene derivatives show inhibitory activity against human immunodeficiency virus reverse transcriptase. Hepatitis C virus RNA polymerase is also inhibited by fullerene derivatives. Therefore, fullerene derivatives are candidate antiviral agents. In addition, fullerene derivatives exhibit antiproliferative activity by inducing apoptosis related to the generation of reactive oxygen species. Fullerene derivatives also have the potential to be anticancer drugs. PMID:22976602

  11. Surface bombardment with highly-charged ions

    SciTech Connect

    Ratliff, L.P.; Bell, E.W.; Parks, D.C.; Pikin, A.I.; Gillaspy, J.D.

    1996-05-01

    The NIST Electron Beam Ion Trap (EBIT) has been modified to be used as a source of low kinetic energy, highly-charged ions. It can produce, for example, a continuous beam of Xe{sup 44+} ions with more than a million counts per second or 7 pA. This beam has been used to bombard surfaces such as mica, CR-39 (polymer) and self-assembled monolayers. The authors characterized the surfaces using techniques including AFM and SEM, and observed single-ion features approximately 15 nm in diameter.

  12. Identification of fullerenes in natural flames by APCI/LCMS

    SciTech Connect

    Taghizadeh, K.; Grieco, W.J.; Lafleur, A.L.; Howard, J.B.

    1995-12-31

    The recent discovery of fullerenes in mineral deposits strongly suggests a natural means of fullerene formation. Previous work in this laboratory showed that fullerenes were relatively abundant in benzene/oxygen flames but not at ambient conditions. Reports of the detection of fullerenes in soots from free-burning toluene and common candle flames under ambient conditions led the authors to explore fullerene formation in natural flames. In this paper, the authors are reporting the detection of fullerenes from six soot samples collected from laboratory small open-flames.

  13. Synthesis and properties of novel fullerene derivatives

    SciTech Connect

    Da Ros, T.; Prato, M.; Guldi, D.; Alessio, E.; Valli, L.; Carano, M.; Paolucci, F.; Ceroni, P.; Roffia, S.

    1998-08-01

    Synthesis and chemical properties of a novel fullerene-porphyrin dyad is reported. Energy/electron transfer is studied based on cyclic voltametry and UV-visible spectroscopy. {copyright} {ital 1998 American Institute of Physics.}

  14. Recent advances in fullerene science (Invited)

    SciTech Connect

    Dunk, P. W.; Marshall, A. G.; Mulet-Gas, M.; Rodriguez-Fortea, A.; Poblet, J. M.

    2014-12-09

    The development of very high resolution FT-ICR mass spectrometers (Marshall et al, 1998) has made a wide range of new measurements possible and by combining this new technology with laser vaporization supersonic beam methods of producing carbon species (chains, rings and fullerenes), new advances in understanding of the fullerene creation mechanisms and their reactivity have been possible. In this overview, new understanding has been developed with regard to: a) closed-network growth of fullerenes (Dunk et al, 2012a); b) small endohedral species such as M?C{sub 28} (Dunk et al., 2012b); c) metallofullerene and fullerene formation under conditions in stellar outflows with relevance to stardust (Dunk et al., 2013a) and d) The formation of heterofullerenes by direct exposure of C{sub 60} toboron vapor (Dunk et al., 2013b)

  15. Photoionization of Endohedral Atoms in Fullerene Cages

    NASA Astrophysics Data System (ADS)

    Lin, C. Y.; Ho, Y. K.

    2013-03-01

    The finite-element discrete variable representation combined with the method of complex coordinate rotation is implemented to investigate the hydrogenic atoms and alkali metals encapsulated by the fullerene cages. The energy levels varying with the confining potential of the fullerene cage exhibit avoided crossings caused by the so-called mirror collapse from the switch of near degenerate states. The effects of fullerene cages on photoionization of confined atoms leading to the oscillation behavior and confinement resonances in photoionization cross sections are demonstrated. The results of cross sections for hydrogen-like lithium ion as a function of the cage radius and shell thickness are presented. The emergence of the Cooper minima due to the influence of the fullerene cages is observed for endohedral lithium and sodium atoms. Comparisons are made to the existing predictions.

  16. Applications of Functionalized Fullerenes in Tumor Theranostics

    PubMed Central

    Chen, Zhiyun; Ma, Lijing; Liu, Ying; Chen, Chunying

    2012-01-01

    Functionalized fullerenes with specific physicochemical properties have been developed for cancer diagnosis and therapy. Notably, metallofullerene is a new class of magnetic resonance imaging (MRI) contrast-enhancing agent, and may have promising applications for clinical diagnosis. Polyhydroxylated and carboxyl fullerenes have been applied to photoacoustic imaging. Moreover, in recent years, functionalized fullerenes have shown potential in tumor therapies, such as photodynamic therapy, photothermal treatment, radiotherapy and chemotherapeutics. Their antitumor effects may be associated with the modulation of oxidative stress, anti-angiogenesis, and immunostimulatory activity. While various types of novel nanoparticle agents have been exploited in tumor theranostics, their distribution, metabolism and toxicity in organisms have also been a source of concern among researchers. The present review summarizes the potential of fullerenes as tumor theranostics agents and their possible underlying mechanisms are discussed. PMID:22509193

  17. Characterizing Fullerene Nanoparticles in Aqueous Suspensions

    EPA Science Inventory

    Studies have indicated that fullerenes can form stable colloidal suspensions in water when introduced to the aqueous phase through solvent exchange, sonication, or extended mixing. The colloidal suspensions created using these techniques have effective aqueous phase concentratio...

  18. Fullerenes broaden scientists' view of molecular structure

    SciTech Connect

    Baum, R.M.

    1993-01-04

    Fullerene research has hit a lull of sorts. The breathless rush of fundamental new science that followed the 1990 discovery of a straight-forward way to synthesize bulk amounts of fullerenes has slacked off in recent months. Nevertheless, a great deal of research on the carbon-cage molecules typified by buckminsterfullerene, C[sub 60] is being carried out, and much of it represents important advances in understanding and manipulating fullerenes. At a week-long symposium at the Materials Research Society (MRS) meeting in early December in Boston, numerous scientists described significant new results on fullerenes and related carbon compounds. And a large number of research papers continue to appear in the scientific literature. This paper summarizes some of the work described at this meeting.

  19. Mechanochemistry of fullerenes and related materials.

    PubMed

    Zhu, San-E; Li, Fei; Wang, Guan-Wu

    2013-09-21

    The low or lack of solubility of fullerenes, carbon nanotubes and graphene/graphite in organic solvents and water severely hampers the study of their chemical functionalizations and practical applications. Covalent and noncovalent functionalizations of fullerenes and related materials via mechanochemistry seem appealing to tackle these problems. In this review article, we provide a comprehensive coverage on the mechanochemical reactions of fullerenes, carbon nanotubes and graphite, including dimerizations and trimerizations, nucleophilic additions, 1,3-dipolar cycloadditions, Diels-Alder reactions, [2 + 1] cycloadditions of carbenes and nitrenes, radical additions, oxidations, etc. It is intriguing to find that some reactions of fullerenes can only proceed under solvent-free conditions or undergo different reaction pathways from those of the liquid-phase counterparts to generate completely different products. We also present the application of the mechanical milling technique to complex formation, nanocomposite formation and enhanced hydrogen storage of carbon-related materials. PMID:23677148

  20. Recent advances in fullerene science (Invited)

    NASA Astrophysics Data System (ADS)

    Dunk, P. W.; Mulet-Gas, M.; Rodriguez-Fortea, A.; Poblet, J. M.; Marshall, A. G.; Kroto, H. W.

    2014-12-01

    The development of very high resolution FT-ICR mass spectrometers (Marshall et al, 1998) has made a wide range of new measurements possible and by combining this new technology with laser vaporization supersonic beam methods of producing carbon species (chains, rings and fullerenes), new advances in understanding of the fullerene creation mechanisms and their reactivity have been possible. In this overview, new understanding has been developed with regard to: a) closed-network growth of fullerenes (Dunk et al, 2012a); b) small endohedral species such as M α C28 (Dunk et al., 2012b); c) metallofullerene and fullerene formation under conditions in stellar outflows with relevance to stardust (Dunk et al., 2013a) and d) The formation of heterofullerenes by direct exposure of C60 toboron vapor (Dunk et al., 2013b).

  1. Adsorption of amino acids by fullerenes and fullerene nanowhiskers

    NASA Astrophysics Data System (ADS)

    Hashizume, Hideo; Hirata, Chika; Fujii, Kazuko; Miyazawa, Kunichi

    2015-12-01

    We have investigated the adsorption of some amino acids and an oligopeptide by fullerene (C60) and fullerene nanowhiskers (FNWs). C60 and FNWs hardly adsorbed amino acids. Most of the amino acids used have a hydrophobic side chain. Ala and Val, with an alkyl chain, were not adsorbed by the C60 or FNWs. Trp, Phe and Pro, with a cyclic structure, were not adsorbed by them either. The aromatic group of C60 did not interact with the side chain. The carboxyl or amino group, with the frame structure of an amino acid, has a positive or negative charge in solution. It is likely that the C60 and FNWs would not prefer the charged carboxyl or amino group. Tri-Ala was adsorbed slightly by the C60 and FNWs. The carboxyl or amino group is not close to the center of the methyl group of Tri-Ala. One of the methyl groups in Tri-Ala would interact with the aromatic structure of the C60 and FNWs. We compared our results with the theoretical interaction of 20 bio-amino acids with C60. The theoretical simulations showed the bonding distance between C60 and an amino acid and the dissociation energy. The dissociation energy was shown to increase in the order, Val < Phe < Pro < Asp < Ala < Trp < Tyr < Arg < Leu. However, the simulation was not consistent with our experimental results. The adsorption of albumin (a protein) by C60 showed the effect on the side chains of Try and Trp. The structure of albumin was changed a little by C60. In our study Try and Tyr were hardly adsorbed by C60 and FNWs. These amino acids did not show a different adsorption behavior compared with other amino acids. The adsorptive behavior of mono-amino acids might be different from that of polypeptides.

  2. Hydrodynamic model of wave-ordered structures formed by ion bombardment of solids

    NASA Astrophysics Data System (ADS)

    Rudy, A. S.; Smirnov, V. K.

    1999-10-01

    The model of a wave-ordered structures (WOS) formed by ion-bombardment on a surfaces of amorphous materials is put forward. The model is based on the assumption that amorphous layer under ion-bombardment may be considered as Newtonian fluid on a hard substrate in the field of external force. Within this approach the mathematical model of an amorphous layer is formulated as a boundary value problem for Navier-Stokes and continuity equations for incompressible liquid. Analysis of the problem results in two quasi-stationary spatial-periodic solutions governed by two control parameters: one of them a? is a capillary constant under a vertical ion beam incidence, normalized to layer thickness, another is an angle of incidence ?. In the general case a capillary constant a?(L,?) is a convex function of both variables viz. normalized spatial-period L and an angle of incidence ?. With energy E0=9 keV this function exhibits a local maximum at L=1.77,?=50.4? which is already global a?c=0.375 when E0=5 keV and (as judged by indirect measurements) becomes more convex with further energy reduction. Collation of a?(L,?) with experimental data reveals that the observed maximum value of capillary constant a?ob=0.367, which due to an inherent supercriticality is a little bit lower than a?c, falls at ?=55?, i.e., with energy diminution angular range should contract to this point. This outcome is consistent with our experimental results on N2+-Si system, manifesting that angular range reduces to a small vicinity of ?cin=55? when ion energy tends to minimum energy of WOS formation E0=1.5 keV.

  3. Crystalline complexes of fullerene with anisole derivatives

    NASA Astrophysics Data System (ADS)

    Markin, G. V.; Baranov, E. V.; Ketkov, S. Yu.; Lopatin, M. A.; Kuropatov, V. A.; Shavyrin, A. S.; Domrachev, G. A.

    2012-03-01

    For the first time, bis(anisole)chromium fulleride (PhO Me)2Cr+·[C60]-· and a crystalline complex of fullerene with ortho-butoxyanisole have been obtained. The temperature dependence of the parameters of the EPR spectrum of bis(anisole)chromium fulleride (PhO Me)2Cr+·[C60]-· has been studied. The molecular structure of the complex of fullerene with ortho-butoxyanisole has been established.

  4. Self-assembly of the fullerenes

    SciTech Connect

    Smalley, R.E. )

    1992-03-01

    The account deals with a central mystery of the fullerene story: How are they made How can the fullerenes in general, and C[sub 60] in particular, possibly, be made spontaneously in high yield simply by condensing carbon vapor in a special way The mystery of how this happens in the case of carbon is still by no means fully resolved. Theories of this process are discussed.

  5. Characterization of fullerenes by mass spectrometry

    SciTech Connect

    McElvany, S.W.; Ross, M.M.; Callahan, J.H. )

    1992-03-01

    The purpose of this account is to describe some of the key, early mass spectrometric studies of gas-phase carbon clusters, which served as a prelude to the Huffman-Kratschmer discovery as well as some of the more recent investigations of fullerene properties in the gas phase. The authors concentrate on analytical investigations of fullerene structure and chemistry as studied by mass spectrometry.

  6. Desorption Induced by KEV Molecular and Cluster Projectiles.

    NASA Astrophysics Data System (ADS)

    Blain, Matthew Glenn

    1990-01-01

    A new experimental method has been developed for studying negative secondary ion (SI) emission from solid surfaces bombarded by polyatomic primary ions of 5 to 30 keV. The method is based on the time-of-flight (TOF) analysis of primary ions which are produced by either ^ {252}Cf fission fragment induced desorption or by extraction from a liquid metal ion source, and then accelerated into a field free region. The primary ions included organic monomer, dimer, and fragment ions of coronene and phenylalanine, (CsI)_ nCs ^{+} cluster ions, and Au _sp{n}{+} cluster ions. Secondary electrons, emitted from a target surface upon primary ion impact, are used to identify which primary ion has hit the surface. An event-by-event coincidence counting technique allows several secondary ion TOF spectra, correlated to several different primary ions, to be acquired simultaneously. Negative SI yields from organic (phenylalanine and dinitrostilbene), CsI, and Au surfaces have been measured for a number of different mono- and polyatomic primary ions. The results show, for example, yields ranging from 1 to 10% for phenylalanine (M-H) ^{ -}, 1 to 10% for I^{-} , and 1 to 5% for Au^{-} , with Cs_2I^ {+} and Cs_3I _sp{2}{+} clusters as projectiles. Yields for the same surfaces using Cs ^{+} primary ions are much less than 1%, indicating that SI yields are enhanced with clusters. A yield enhancement occurs when the SI yield per atom of a polyatomic projectile is greater than the SI yield of its monoatomic equivalent, at the same velocity. Thus, a (M-H) ^{-} yield increase of a factor of 50, when phenylalanine is bombarded with Cs_3I_sp{2} {+} instead of Cs^{+ }, represents a yield enhancement factor of 10. For the projectiles and samples studied, it was observed that the heavier the mass of the constituents of a projectile, the larger the enhancement effects, and that the largest yield enhancements (with CsI and Au _ n projectiles) occur for the organic target, phenylalanine. One possible explanation for the larger enhancements with organics, namely a thermal spike process, appears unlikely. Experiments with high and low melting point isomers of dinitrostilbene, bombarded with Cs _2I^{+} and Cs^{+} projectiles, showed larger Cs_2I^ {+} yield enhancements for the high melting point isomer.

  7. Fullerene growth from encapsulated graphene flakes

    NASA Astrophysics Data System (ADS)

    Neng, Wan; Shuang-Ying, Lei; Jun, Xu; Matteo, Martini; Yi-Long, Zhou; Shu, Wan; Li-Tao, Sun; Qing-An, Huang

    2014-09-01

    The direct in situ observation of fullerene formation encapsulated within a graphene ridge has been made possible using an aberration corrected transmission electron microscope (AC-TEM). An atom-by-atom mechanism was proposed based on in situ AC-TEM observations. First principle calculations found a continuous energy decrease upon the addition of carbon atoms to the edge of the graphene flakes, which mimics the fullerene growth steps and supports the atom-by-atom mechanism. The ridged graphene structure worked as a container for pinning small graphene flakes and capturing carbon atoms, which increased the growth probability of the fullerene structure within the small encapsulated space.The direct in situ observation of fullerene formation encapsulated within a graphene ridge has been made possible using an aberration corrected transmission electron microscope (AC-TEM). An atom-by-atom mechanism was proposed based on in situ AC-TEM observations. First principle calculations found a continuous energy decrease upon the addition of carbon atoms to the edge of the graphene flakes, which mimics the fullerene growth steps and supports the atom-by-atom mechanism. The ridged graphene structure worked as a container for pinning small graphene flakes and capturing carbon atoms, which increased the growth probability of the fullerene structure within the small encapsulated space. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03680h

  8. Phase formation in Au-Al and Cu-Al thin-film systems under ion beam bombardment

    SciTech Connect

    Chang, C.T.; Campisano, S.U.; Cannavo, S.; Rimini, E.

    1984-05-01

    Au-Al and Cu-Al thin film bilayers were bombarded at 80 K with Kr/sup +/ ions of 60--240 keV energy. The Au/sub 2/Al+AuAl/sub 2/ and Al/sub 4/Cu/sub 9/ phases formed during bombardment and they were investigated by backscattering and x-ray diffraction techniques. In all the cases the growth kinetics is linear with the parameter (fluence x interfacial deposited energy density)/sup 1//sup ///sup 2/ suggesting a correlation with a diffusion-like process. Comparison with calculations of diffusion enhanced within the collision cascade gives good agreement with the experimental results.

  9. Program fullerene: a software package for constructing and analyzing structures of regular fullerenes.

    PubMed

    Schwerdtfeger, Peter; Wirz, Lukas; Avery, James

    2013-06-30

    Fullerene (Version 4.4) is a general purpose open-source program that can generate any fullerene isomer, perform topological and graph theoretical analysis, as well as calculate a number of physical and chemical properties. The program creates symmetric planar drawings of the fullerene graph and generates accurate molecular 3D geometries by way of force-field optimization, serving as a good starting point for further quantum theoretical treatments. It includes a number of fullerene-to-fullerene transformations, such as Goldberg-Coxeter transforms, Stone-Wales transforms, Endo-Kroto, Yoshida-Fowler, and Brinkmann-Fowler vertex insertions. The program is written in standard Fortran and C++ and can easily be installed in a Linux or UNIX environment. PMID:23559399

  10. Paper Models for Fullerenes C60-C84.

    ERIC Educational Resources Information Center

    Beaton, John M.

    1995-01-01

    Describes a system to construct paper models of all 51 of the possible fullerene isomers from C60 through C84. Provides students, teachers, and specialists with an inexpensive mechanism to follow the literature interplay on fullerene structures. (JRH)

  11. Fullerene surfactants and their use in polymer solar cells

    SciTech Connect

    Jen, Kwan-Yue; Yip, Hin-Lap; Li, Chang-Zhi

    2015-12-15

    Fullerene surfactant compounds useful as interfacial layer in polymer solar cells to enhance solar cell efficiency. Polymer solar cell including a fullerene surfactant-containing interfacial layer intermediate cathode and active layer.

  12. Geometrical and electronic rules in fullerene-based compounds.

    PubMed

    Gan, Li-Hua; An, Jie; Pan, Fu-Sheng; Chang, Qing; Liu, Zuo-Hua; Tao, Chang-Yuan

    2011-06-01

    The discovery of buckminsterfullerene C(60) opened up a new scientific area and stimulated the development of nanoscience and nanotechnology directly. Fullerene science has since emerged to include fullerenes, endohedral fullerenes (mainly metallofullerenes), exofullerenes, and carbon nanotubes as well. Herein, we look back at the development of fullerene science from the perspective of epistemology by highlighting the proposed main rules or criteria for understanding and predicting the structures and stability of fullerene-based compounds. We also point out that a rule or criterion may contribute significantly to the corresponding discipline and suggest that two unsolved issues in fullerene science are the addition patterns of fullerene derivatives and the structures and stability of nonclassical fullerenes. PMID:21480535

  13. Synthesis and spectroscopy studies of fullerenes and discovery of macroscopic quantities of doped fullerenes

    SciTech Connect

    Chai, Yan.

    1992-01-01

    Synthesis techniques of carbon arc and laser vaporization in the furnace for production of fullerenes have been developed. The optimum conditions for the high yields of fullerenes were tested and studied. A fullerene growth model was proposed to explain the formation of the fullerenes and the extraordinary high yield of C[sub 60]. The results of a test of this growth model was in agreement with the implications of the model. The electronic spectra of neutral C[sub 60] and C[sub 70] in the regions from 375 to 415 nm and 595 to 640 nm have been studied in a supersonically cooled molecular beam by resonant two-photon ionization spectroscopy method. Sharp spectal features were observed in both regions for C[sub 60] and in only the longer wavelength region for C[sub 70]. Neither molecule has the spectra that correspond to the diffuse interstellar bands. The first method to produce macroscopic quantities of internal metal-doped fullerenes was developed successfully and improved. Lanthanum-doped fullerenes were produced by laser vaporization of a lanthanum oxide/graphite composite rod in a flow of argon at 1200[degrees]C. Many properties of these endohedral complexes were investigated in detail. Similar results were obtained with yttrium-doped fullerenes, and double-doped endohedral fullerene complexes were first observed as a stable species in both sublimed film and toluene solution. Macroscopic quantities of other interesting metal-doped or B-doped fullerenes have been obtained and studied. Purification of these metal-doped fullerenes is in the process.

  14. Beyond Bombardment: Subjectivity, Visual Culture, and Art Education

    ERIC Educational Resources Information Center

    Eisenhauer, Jennifer F.

    2006-01-01

    Beginning with an understanding of visual culture as a postmodern discourse, this article argues for more focused attention to how visual culture presents a critical rethinking of subjectivity within art education. Through an analysis of a language of bombardment, a discourse that positions the subject as bombarded by media messages, this article

  15. Modelling the structure of ion bombarded binary alloys

    SciTech Connect

    Ossi, P.M.

    1995-09-01

    An atomistic model of phase formation in ion bombarded thin binary metallic films is discussed. Compositional changes occur at the interface between collision cascades and crystal matrix. Relaxation arises via elementary charge transfer reactions, with formation of dimers of an effective alloys, a set of conditions specific to vitrification and respectively to crystal formation under ion bombardment is obtained.

  16. Constructing I[subscript h] Symmetrical Fullerenes from Pentagons

    ERIC Educational Resources Information Center

    Gan, Li-Hua

    2008-01-01

    Twelve pentagons are sufficient and necessary to form a fullerene cage. According to this structural feature of fullerenes, we propose a simple and efficient method for the construction of I[subscript h] symmetrical fullerenes from pentagons. This method does not require complicated mathematical knowledge; yet it provides an excellent paradigm for…

  17. Constructing I[subscript h] Symmetrical Fullerenes from Pentagons

    ERIC Educational Resources Information Center

    Gan, Li-Hua

    2008-01-01

    Twelve pentagons are sufficient and necessary to form a fullerene cage. According to this structural feature of fullerenes, we propose a simple and efficient method for the construction of I[subscript h] symmetrical fullerenes from pentagons. This method does not require complicated mathematical knowledge; yet it provides an excellent paradigm for

  18. Effects of fullerene C60 nanocomposites on human platelet aggregation.

    PubMed

    Vaschenko, V I; Samonin, V V; Popov, V A; Antonenkova, E V; Nikonova, V J; Vilyaninov, V N; Podvjaznikov, M L; Kidalov, V N; Titulova, T B; Vaschenko, T N

    2012-03-01

    The effects of fullerene C(60) nanocomposites on human platelet aggregation induced by ADP, ristocetin, and collagen were studied. The nanocomposite containing fullerene C(60) in polyvinyl pyrrolidone solution did not change platelet aggregation, while fullerene C(60) in crown ether and Twin-80 solutions inhibited ADP-induced platelet aggregation by 20 and 30%, respectively. PMID:22803150

  19. INFRARED STUDY OF FULLERENE PLANETARY NEBULAE

    SciTech Connect

    Garcia-Hernandez, D. A.; Acosta-Pulido, J. A.; Manchado, A.; Garcia-Lario, P.; Stanghellini, L.; Shaw, R. A.; Cataldo, F. E-mail: amt@iac.es E-mail: Pedro.Garcia-Lario@sciops.esa.int E-mail: letizia@noao.edu

    2012-12-01

    We present a study of 16 planetary nebulae (PNe) where fullerenes have been detected in their Spitzer Space Telescope spectra. This large sample of objects offers a unique opportunity to test conditions of fullerene formation and survival under different metallicity environments because we are analyzing five sources in our own Galaxy, four in the Large Magellanic Cloud (LMC), and seven in the Small Magellanic Cloud (SMC). Among the 16 PNe studied, we present the first detection of C{sub 60} (and possibly also C{sub 70}) fullerenes in the PN M 1-60 as well as of the unusual {approx}6.6, 9.8, and 20 {mu}m features (attributed to possible planar C{sub 24}) in the PN K 3-54. Although selection effects in the original samples of PNe observed with Spitzer may play a potentially significant role in the statistics, we find that the detection rate of fullerenes in C-rich PNe increases with decreasing metallicity ({approx}5% in the Galaxy, {approx}20% in the LMC, and {approx}44% in the SMC) and we interpret this as a possible consequence of the limited dust processing occurring in Magellanic Cloud (MC) PNe. CLOUDY photoionization modeling matches the observed IR fluxes with central stars that display a rather narrow range in effective temperature ({approx}30,000-45,000 K), suggesting a common evolutionary status of the objects and similar fullerene formation conditions. Furthermore, the data suggest that fullerene PNe likely evolve from low-mass progenitors and are usually of low excitation. We do not find a metallicity dependence on the estimated fullerene abundances. The observed C{sub 60} intensity ratios in the Galactic sources confirm our previous finding in the MCs that the fullerene emission is not excited by the UV radiation from the central star. CLOUDY models also show that line- and wind-blanketed model atmospheres can explain many of the observed [Ne III]/[Ne II] ratios using photoionization, suggesting that possibly the UV radiation from the central star, and not shocks, is triggering the decomposition of the circumstellar dust grains. With the data at hand, we suggest that the most likely explanation for the formation of fullerenes and graphene precursors in PNe is that these molecular species are built from the photochemical processing of a carbonaceous compound with a mixture of aromatic and aliphatic structures similar to that of hydrogenated amorphous carbon dust.

  20. Spacecraft charging investigation for the CTS project. [electric insulator surface tests by electron bombardment for Communications Technology Satellite

    NASA Technical Reports Server (NTRS)

    Stevens, N. J.; Lovell, R. R.; Gore, V.

    1975-01-01

    Results to date are presented for a program of analytical and experimental investigations to assess the impact of discharge pulses from spacecraft surfaces in the joint Canadian-American Communications Technology Satellite (CTS). All insulator surfaces tested experienced visible discharges when subjected to an electron beam with energy greater than 10 keV. Discharge rate was found to be a function of current flux. The deployable solar array sample experienced discharges under bombardment from the cell or kapton side. There was no measurable cell performance degradation due to the discharges.

  1. Magnetization reversal of Co/Au multilayer stripes with keV-He+ ion bombardment induced coercivity gradient

    NASA Astrophysics Data System (ADS)

    Urbaniak, M.; Stobiecki, F.; Gaul, A.; Ehresmann, A.

    2015-08-01

    Magnetization reversal of perpendicular anisotropy [Co/Au]\\text{N} multilayers patterned into micrometer wide stripes with a coercivity gradient along the stripes was investigated with polar magnetooptical Kerr effect microscopy. 1 mm-long stripes were bombarded with He+ ions of 10 keV energy to induce the gradient. It was shown that short pulses of a magnetic field applied perpendicularly to the sample plane move domain walls between up- and down-magnetized areas in a direction of regions with higher coercivities.

  2. Synthesis of Fullerene-Fused Dioxanes/Dioxepanes: Ferric Perchlorate-Mediated One-Step Reaction of [60]Fullerene with Diols.

    PubMed

    Zhang, Xiao-Feng; Li, Fa-Bao; Wu, Jun; Shi, Ji-Long; Liu, Zhan; Liu, Li

    2015-06-19

    The facile one-step reaction of [60]fullerene with various diols in the presence of ferric perchlorate afforded a series of rare fullerene-fused dioxanes/dioxepanes. Nevertheless, the reaction of [60]fullerene with diethylene glycol, triethylene glycol, and tripropylene glycol promoted by ferric perchlorate unexpectedly generated fullerene-fused dioxanes instead of the anticipated fullerene-fused crown ethers. A plausible reaction mechanism is proposed to explain the formation of fullerene-fused dioxane/dioxepane products. PMID:25996442

  3. Materials science: C66 fullerene encaging a scandium dimer

    NASA Astrophysics Data System (ADS)

    Wang, Chun-Ru; Kai, Tsutomu; Tomiyama, Tetsuo; Yoshida, Takuya; Kobayashi, Yuji; Nishibori, Eiji; Takata, Masaki; Sakata, Makoto; Shinohara, Hisanori

    2000-11-01

    The geometry of carbon cages (fullerenes) is governed by the isolated-pentagon rule (IPR), which states that the most stable fullerenes are those in which all pentagons are surrounded by five hexagons. Although this rule has been verified experimentally, it is impossible for fullerenes in the range C60 to C70 to obey it. Here we describe the production and characterization of an IPR-violating metallofullerene, Sc2@C66, a C66 fullerene encaging a scandium dimer. Our results indicate that encapsulation of the metal dimer significantly stabilizes this otherwise extremely unstable C66 fullerene.

  4. Modifications in the chemical bonding and optical absorption of PPS by ion bombardment

    NASA Astrophysics Data System (ADS)

    Farenzena, L. S.; Papaléo, R. M.; Hallén, A.; de Araújo, M. A.; Livi, R. P.; Sundqvist, B. U. R.

    1995-11-01

    Commercial-grade thin poly(p-phenylene sulphide) (PPS) foils, 2 μm thick, have been bombarded with 1H + (380 keV), and with 0.61 MeV/amu 4He +, 12C 2+, 16O 3+, 32S 3+, 79Br 9+ and 127I 14+ ions. The completely modified foils have been analyzed by Fourier transform infrared absorption spectroscopy (FTIR) and by ultraviolet-visible absorption spectroscopy (UV-VIS). The bond breaking and rearrangement processes were followed by using the FTIR results. The absorbance of bands related to CS, SS, CH and most of the ring carbon bonds show an exponential decrease as a function of fluence. The absorption bands most sensitive to the ion bombardment are those assigned to CS and SS bonds. The CC and CH bonds are less sensitive and certain absorption band changes indicate carbon-carbon aliphatic and or aromatic conjugation, due to their increasing intensity as a function of the ion fluence. Damage cross sections have been extracted from the plots of IR absorbance versus fluence. The values of the damage cross sections obtained scale roughly with the square of {dE }/{dx } (independent of the nature of the chemical bond). The optical absorption coefficient has also been followed as a function of the ion fluence.

  5. Influence of secondary ion bombardment on the composition, structure and surface properties of platinum thin films

    NASA Astrophysics Data System (ADS)

    Balaji, S.; Satyam, P. V.; Lakshminarayanan, V.; Mohan, S.

    2004-05-01

    Platinum (Pt) thin films were deposited by dual ion beam sputtering (DIBS) techniques on oxidized silicon substrates maintained at ambient temperature. Argon ions with energy of 1 keV and beam current of 15 mA were used to sputter the platinum target. The films during deposition were continuously bombarded by argon from a secondary argon ion source with ion energy of 150 eV and ion current density in the range 100-250 ?A/cm 2. The influence of the secondary ion beam parameters on the grain size, composition and surface morphology of the films were studied. X-ray diffraction (XRD) of all the films showed (1 1 1) orientation with other reflections being absent which is a stable structure for FCC crystals. The grain size of the Pt films prepared by DIBS at ambient temperature were found to be higher than those prepared at higher substrate temperature by low energy plasma sputtering. The presence of Ar impurities in the sputter deposited thin films is known to modify their properties. In this paper we report a method to control the Ar content in the films by secondary Ar ion bombardment of the growing films. The modification of the surface features by secondary ion beam current was studied by scanning tunneling microscope and is also presented in this paper. The surface analysis indicates a decrease in the surface roughness for the Pt films prepared at a secondary ion beam current density of 150 ?A/cm 2.

  6. Fullerenes as sorbent materials for metal preconcentration

    SciTech Connect

    Gallego, M.; Pena, Y.P. de; Valcarcel, M. )

    1994-11-15

    The analytical potential of C[sub 60] fullerenes as sorbent materials for preconcentration of metal traces by formation of neutral chelates was studied for the first time in this work. The model system used for this purpose was the determination of lead traces in waters by using ammonium pyrrolidinedithiocarbamate as ligand. The chelate is formed in a continuous-flow system, sorbed on a C[sub 60] fullerene minicolumn, and subsequently eluted for transfer to an atomic absorption spectrometer. Two other simultaneous batches of experiments were performed in parallel by using C[sub 18] bonded silica and activated carbon as sorbents in order to study the features of the new sorbent material and its advantages. The primary assets of C[sub 60] fullerenes in this respect are a high sensitivity arising from efficient adsorption and also high selectivity derived from the special features of this new type of sorbent material. 27 refs., 3 figs., 2 tabs.

  7. Production of fullerenes using concentrated solar flux

    DOEpatents

    Fields, Clark L. (Greeley, CO); Pitts, John Roland (Lakewood, CO); King, David E. (Lakewood, CO); Hale, Mary Jane (Golden, CO); Bingham, Carl E. (Denver, CO); Lewandowski, Allan A. (Evergreen, CO)

    2000-01-01

    A method of producing soot containing high amounts of fullerenes comprising: providing a primary concentrator capable of impingement of a concentrated beam of sunlight onto a carbon source to cause vaporization of carbon and subsequent formation of fullerenes, or providing a solar furnace having a primary concentrator with a focal point that concentrates a solar beam of sunlight; providing a reflective secondary concentrator having an entrance aperture and an exit aperture at the focal point of the solar furnace; providing a carbon source at the exit aperture of the secondary concentrator; supplying an inert gas over the carbon source to keep the secondary concentrator free from vaporized carbon; and impinging a concentrated beam of sunlight from the secondary concentrator on the carbon source to vaporize the carbon source into a soot containing high amounts of fullerenes.

  8. Superconductivity in cage doped fullerenes. Final report

    SciTech Connect

    Labes, M.M.

    1996-08-26

    Motivated by the discovery of superconductivity in alkali and alkaline earth fullerides, this program was undertaken both to understand the nature of and expand the range of materials demonstrating superconductivity. The first approach involved attempts to modify the fullerene cage by incorporating heteroatoms in the structure and the preparation and photophysical properties of nitrogen and sulfur doped fullerenes were studied in detail. The second approach involved examining the stoichiometry and effect of preparative conditions on the behavior of alkali, alkaline earth, lanthanide and mixed ion fullerides. In particular, the authors have elaborated on a technique for making such salts using liquid ammonia or aliphatic amines as solvents. Thirdly, modeling studies were undertaken to predict the properties of heterohedral fullerines and metal - C60 complexes, and theoretical guidelines were developed for understanding the reactivity of the fullerene cage to common addition reagents.

  9. Site specific atomic polarizabilities in endohedral fullerenes and carbon onions.

    PubMed

    Zope, Rajendra R; Bhusal, Shusil; Basurto, Luis; Baruah, Tunna; Jackson, Koblar

    2015-08-28

    We investigate the polarizability of trimetallic nitride endohedral fullerenes by partitioning the total polarizability into site specific components. This analysis indicates that the polarizability of the endohedral fullerene is essentially due to the outer fullerene cage and has insignificant contribution from the encapsulated unit. Thus, the outer fullerene cages effectively shield the encapsulated clusters and behave like Faraday cages. The polarizability of endohedral fullerenes is slightly smaller than the polarizability of the corresponding bare carbon fullerenes. The application of the site specific polarizabilities to C60@C240 and C60@C180 onions shows that, compared to the polarizability of isolated C60 fullerene, the encapsulation of the C60 in C240 and C180 fullerenes reduces its polarizability by 75% and 83%, respectively. The differences in the polarizability of C60 in the two onions is a result of differences in the bonding (intershell electron transfer), fullerene shell relaxations, and intershell separations. The site specific analysis further shows that the outer atoms in a fullerene shell contribute most to the fullerene polarizability. PMID:26328842

  10. Fullerenes in an impact crater on the LDEF spacecraft

    NASA Technical Reports Server (NTRS)

    Radicati di Brozolo, F.; Bunch, T. E.; Fleming, R. H.; Macklin, J.

    1994-01-01

    The fullerenes C60 and C70 have been found to occur naturally on Earth and have also been invoked to explain features in the absorption spectra of interstellar clouds. But no definitive spectroscopic evidence exists for fullerenes in space and attempts to find fullerenes in carbonaceous chondrites have been unsuccessful. Here we report the observation of fullerenes associated with carbonaceous impact residue in a crater on the Long Duration Exposure Facility (LDEF) spacecraft. Laser ionization mass spectrometry and Raman spectroscopy indicate the presence of fullerenes in the crater and in adjacent ejecta. Man-made fullerenes survive experimental hypervelocity (approximately 6.1 km s-1) impacts into aluminium targets, suggesting that space fullerenes contained in a carbonaceous micrometeorite could have survived the LDEF impact at velocities towards the lower end of the natural particle encounter range (<13 km s-1). We also demonstrate that the fullerenes were unlikely to have formed as instrumental artefacts, nor are they present as contaminants. Although we cannot specify the origin of the fullerenes with certainty, the most plausible source is the chondritic impactor. If, alternatively, the impact produced the fullerenes in situ on LDEF, then this suggests a viable mechanism for fullerene production in space.

  11. Site specific atomic polarizabilities in endohedral fullerenes and carbon onions

    NASA Astrophysics Data System (ADS)

    Zope, Rajendra R.; Bhusal, Shusil; Basurto, Luis; Baruah, Tunna; Jackson, Koblar

    2015-08-01

    We investigate the polarizability of trimetallic nitride endohedral fullerenes by partitioning the total polarizability into site specific components. This analysis indicates that the polarizability of the endohedral fullerene is essentially due to the outer fullerene cage and has insignificant contribution from the encapsulated unit. Thus, the outer fullerene cages effectively shield the encapsulated clusters and behave like Faraday cages. The polarizability of endohedral fullerenes is slightly smaller than the polarizability of the corresponding bare carbon fullerenes. The application of the site specific polarizabilities to C60@C240 and C60@C180 onions shows that, compared to the polarizability of isolated C60 fullerene, the encapsulation of the C60 in C240 and C180 fullerenes reduces its polarizability by 75% and 83%, respectively. The differences in the polarizability of C60 in the two onions is a result of differences in the bonding (intershell electron transfer), fullerene shell relaxations, and intershell separations. The site specific analysis further shows that the outer atoms in a fullerene shell contribute most to the fullerene polarizability.

  12. Distributed curvature and stability of fullerenes.

    PubMed

    Fowler, Patrick W; Nikolić, Sonja; De Los Reyes, Rasthy; Myrvold, Wendy

    2015-09-21

    Energies of non-planar conjugated π systems are typically described qualitatively in terms of the balance of π stabilisation and the steric strain associated with geometric curvature. Curvature also has a purely graph-theoretical description: combinatorial curvature at a vertex of a polyhedral graph is defined as one minus half the vertex degree plus the sum of reciprocal sizes of the faces meeting at that vertex. Prisms and antiprisms have positive combinatorial vertex curvature at every vertex. Excluding these two infinite families, we call any other polyhedron with everywhere positive combinatorial curvature a PCC polyhedron. Cubic PCC polyhedra are initially common, but must eventually die out with increasing vertex count; the largest example constructed so far has 132 vertices. The fullerenes Cn have cubic polyhedral molecular graphs with n vertices, 12 pentagonal and (n/2 - 10) hexagonal faces. We show that there are exactly 39 PCC fullerenes, all in the range 20 ≤n≤ 60. In this range, there is only partial correlation between PCC status and stability as defined by minimum pentagon adjacency. The sum of vertex curvatures is 2 for any polyhedron; for fullerenes the sum of squared vertex curvatures is linearly related to the number of pentagon adjacencies and hence is a direct measure of relative stability of the lower (n≤ 60) fullerenes. For n≥ 62, non-PCC fullerenes with a minimum number of pentagon adjacencies minimise mean-square curvature. For n≥ 70, minimum mean-square curvature implies isolation of pentagons, which is the strongest indicator of stability for a bare fullerene. PMID:26283188

  13. A highly-ordered 3D covalent fullerene framework.

    PubMed

    Minar, Norma K; Hou, Kun; Westermeier, Christian; Dblinger, Markus; Schuster, Jrg; Hanusch, Fabian C; Nickel, Bert; Ozin, Geoffrey A; Bein, Thomas

    2015-06-22

    A highly-ordered 3D covalent fullerene framework is presented with a structure based on octahedrally functionalized fullerene building blocks in which every fullerene is separated from the next by six functional groups and whose mesoporosity is controlled by cooperative self-assembly with a liquid-crystalline block copolymer. The new fullerene-framework material was obtained in the form of supported films by spin coating the synthesis solution directly on glass or silicon substrates, followed by a heat treatment. The fullerene building blocks coassemble with a liquid-crystalline block copolymer to produce a highly ordered covalent fullerene framework with orthorhombic Fmmm symmetry, accessible 7.5?nm pores, and high surface area, as revealed by gas adsorption, NMR spectroscopy, small-angle X-ray scattering (SAXS), and TEM. We also note that the 3D covalent fullerene framework exhibits a dielectric constant significantly lower than that of the nonporous precursor material. PMID:25958846

  14. A Highly-Ordered 3D Covalent Fullerene Framework**

    PubMed Central

    Minar, Norma K; Hou, Kun; Westermeier, Christian; Dblinger, Markus; Schuster, Jrg; Hanusch, Fabian C; Nickel, Bert; Ozin, Geoffrey A; Bein, Thomas

    2015-01-01

    A highly-ordered 3D covalent fullerene framework is presented with a structure based on octahedrally functionalized fullerene building blocks in which every fullerene is separated from the next by six functional groups and whose mesoporosity is controlled by cooperative self-assembly with a liquid-crystalline block copolymer. The new fullerene-framework material was obtained in the form of supported films by spin coating the synthesis solution directly on glass or silicon substrates, followed by a heat treatment. The fullerene building blocks coassemble with a liquid-crystalline block copolymer to produce a highly ordered covalent fullerene framework with orthorhombic Fmmm symmetry, accessible 7.5?nm pores, and high surface area, as revealed by gas adsorption, NMR spectroscopy, small-angle X-ray scattering (SAXS), and TEM. We also note that the 3D covalent fullerene framework exhibits a dielectric constant significantly lower than that of the nonporous precursor material. PMID:25958846

  15. Biomedical applications of functionalized fullerene-based nanomaterials

    PubMed Central

    Partha, Ranga; Conyers, Jodie L

    2009-01-01

    Since their discovery in 1985, fullerenes have been investigated extensively due to their unique physical and chemical properties. In recent years, studies on functionalized fullerenes for various applications in the field of biomedical sciences have seen a significant increase. The ultimate goal is towards employing these functionalized fullerenes in the diagnosis and therapy of human diseases. Functionalized fullerenes are one of the many different classes of compounds that are currently being investigated in the rapidly emerging field of nanomedicine. In this review, the focus is on the three categories of drug delivery, reactive oxygen species quenching, and targeted imaging for which functionalized fullerenes have been studied in depth. In addition, an exhaustive list of the different classes of functionalized fullerenes along with their applications is provided. We will also discuss and summarize the unique approaches, mechanisms, advantages, and the aspect of toxicity behind utilizing functionalized fullerenes for biomedical applications. PMID:20011243

  16. Endohedral and exohedral hybrids involving fullerenes and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Vizuete, Mara; Barrejn, Myriam; Gmez-Escalonilla, Mara Jos; Langa, Fernando

    2012-07-01

    Since fullerenes and carbon nanotubes (CNTs) were discovered, these materials have attracted a great deal of attention in the scientific community due to their unique structures and properties. The properties of both carbon allotropes can be modulated by chemical functionalization, and merging fullerenes and CNTs combines the electronic and optical properties of CNTs with the excellent electron acceptor characteristic of fullerenes; moreover, a synergistic effect of these hybrids can be found, as the properties of both the nanotube and the fullerene are affected by the presence of the other. In these hybrids, the fullerene can be located inside (endohedral) or outside (exohedral) the CNT and both types of hybrid have specific features. CNT-fullerene hybrids have been studied for various applications, including photovoltaics, optical limiting and flame retardancy amongst others. This review outlines the progress in research on CNT-fullerene hybrids, including endohedral and exohedral combinations, their properties, functionalization, applications and outlook.

  17. Reactions of fullerene oxides in a fourier-transform mass spectrometer

    SciTech Connect

    Holliman, C.; McElvany, S.

    1995-12-31

    High-intensity laser desorption of C{sub 60} fullerene results in the formation of larger fullerenes through coalescence. Fullerene coalescence appears to occur via the emission of small even-numbered carbon species. An understanding of the coalescence mechanism should provide insight into the fullerene growth process and may direct new synthetic routes to the macroscopic production of larger fullerenes.

  18. Solubilization of fullerenes, carbon nanotubes, and graphene.

    PubMed

    Pnicaud, Alain

    2014-01-01

    Processing of novel carbon forms, i.e. fullerenes, nanotubes and graphene, in solution is described. C60 and higher fullerenes appear to be the only truly soluble forms of pure carbon. Ways to disperse carbon nanotubes and graphene are reviewed. True solutions of carbon nanotubes and graphene can be obtained by reductive dissolution, leading to solution of polyelectrolyte nanocarbons of high concentrations without damaging the nanocarbon. Finally it is shown that these solutions allow to obtain high performing materials such as highly conducting transparent electrodes. PMID:24647837

  19. Energy spectrum of C60 fullerene

    NASA Astrophysics Data System (ADS)

    Mironov, G. I.; Murzashev, A. I.

    2011-11-01

    The energy spectrum of the C60 fullerene has been calculated in terms of the Shubin-Vonsovskii-Hubbard model using an approximation of static fluctuations. Based on the spectrum, the optical absorption bands at 4.84, 5.88, and 6.30 eV observed experimentally have been successfully explained. It has been concluded that the model used is applicable for the calculation of the energy spectrum and the energy properties of other nanosystems, such as fullerenes of higher orders, carbon nanotubes, and grafen planes.

  20. Laser controlled magnetism in hydrogenated fullerene films

    SciTech Connect

    Makarova, Tatiana L.; Shelankov, Andrei L.; Kvyatkovskii, Oleg E.; Zakharova, Irina B.; Buga, Sergei G.; Volkov, Aleksandr P.

    2011-04-15

    Room temperature ferromagnetic-like behavior in fullerene photopolymerized films treated with monatomic hydrogen is reported. The hydrogen treatment controllably varies the paramagnetic spin concentration and laser induced polymerization transforms the paramagnetic phase to a ferromagnetic-like one. Excess laser irradiation destroys magnetic ordering, presumably due to structural changes, which was continuously monitored by Raman spectroscopy. We suggest an interpretation of the data based on first-principles density-functional spin-unrestricted calculations which show that the excess spin from mono-atomic hydrogen is delocalized within the host fullerene and the laser-induced polymerization promotes spin exchange interaction and spin alignment in the polymerized phase.

  1. Modification of Polymer Materials by Ion Bombardment: Case Studies

    SciTech Connect

    Bielinski, D. M.; Jagielski, J.; Piatkowska, A.

    2009-03-10

    The paper discusses possibility of application of ion beam bombardment for modification of polymers. Changes to composition, structure and morphology of the surface layer produced by the treatment and their influence on engineering and functional properties of wide range of polymer materials are presented. Special attention has been devoted to modification of tribological properties. Ion bombardment results in significant reduction of friction, which can be explained by increase of hardness and wettability of polymer materials. Hard but thin enough skin does not result in cracking but improves their abrasion resistance. Contrary to conventional chemical treatment ion beam bombardment works even for polymers hardly susceptible to modification like silicone rubber or polyolefines.

  2. Transgenic sorghum plants via microprojectile bombardment.

    PubMed Central

    Casas, A M; Kononowicz, A K; Zehr, U B; Tomes, D T; Axtell, J D; Butler, L G; Bressan, R A; Hasegawa, P M

    1993-01-01

    Transgenic sorghum plants have been obtained after microprojectile bombardment of immature zygotic embryos of a drought-resistant sorghum cultivar, P898012. DNA delivery parameters were optimized based on transient expression of R and C1 maize anthocyanin regulatory elements in scutellar cells. The protocol for obtaining transgenic plants consists of the delivery of the bar gene to immature zygotic embryos and the imposition of bialaphos selection pressure at various stages during culture, from induction of somatic embryogenesis to rooting of regenerated plantlets. One in about every 350 embryos produced embryogenic tissues that survived bialaphos treatment; six transformed callus lines were obtained from three of the eight sorghum cultivars used in this research. Transgenic (T0) plants were obtained from cultivar P898012 (two independent transformation events). The presence of the bar and uidA genes in the T0 plants was confirmed by Southern blot analysis of genomic DNA. Phosphinothricin acetyltransferase activity was detected in extracts of the T0 plants. These plants were resistant to local application of the herbicide Ignite/Basta, and the resistance was inherited in T1 plants as a single dominant locus. Images Fig. 1 Fig. 2 Fig. 4 Fig. 5 PMID:8248230

  3. Genetic transformation of wheat via particle bombardment.

    PubMed

    Sparks, Caroline A; Jones, Huw D

    2014-01-01

    Since its first invention in the late 1980s the particle gun has evolved from a basic gunpowder driven machine firing tungsten particles to one more refined which uses helium gas as the propellant to launch alternative heavy metal particles such as gold and silver. The simple principle is that DNA-coated microscopic particles (microcarriers) are accelerated at high speed by helium gas within a vacuum and travel at such a velocity as to penetrate target cells. However, the process itself involves a range of parameters which are open to variation: microparticle type and size, gun settings (rupture pressure, target distance, vacuum drawn, etc.), preparation of components (e.g., gold coating), and preparation of plant tissues. Here is presented a method optimized for transformation of wheat immature embryos using the Bio-Rad PDS-1000/He particle gun to deliver gold particles coated with a gene of interest and the selectable marker gene bar at 650 psi rupture pressure. Following bombardment, various tissue culture phases are used to encourage embryogenic callus formation and regeneration of plantlets and subsequent selection using glufosinate ammonium causes suppression of non-transformed tissues, thus assisting the detection of transformed plants. This protocol has been used successfully to generate transgenic plants for a wide range of wheat varieties, both spring and winter bread wheats (T. aestivum L.) and durum wheats (T. turgidum L.). PMID:24243206

  4. Production of Mg and Al Auger electrons by noble gas ion bombardment of Mg and Al surfaces

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Pepper, S. V.

    1976-01-01

    Relative production efficiencies of Mg and Al Auger electrons by He, Ne, Ar, Kr, and Xe ion bombardment are reported as a function of ion energy for energies not exceeding 3 keV. The experimental apparatus employed consisted of a LEED-Auger system equipped with an ion gun and a four-grid retarding-potential analyzer. It is found that: (1) the shape of the ion-excited Auger signal was independent of the rare gas and quite symmetric; (2) the Al signal was about an order of magnitude smaller than the Mg signal for a given bombarding species and ion-gun voltage; (3) no signal was observed for He(+) bombardment under any of the experimental conditions; (4) signal strengths were independent of temperature and ion dose; (5) the Auger production efficiencies differed by no more than a factor of two among the different gases - except for He(+) - on a given metal; (6) all the signal strengths increased with increasing ion-gun voltage, with no maximum exhibited; and (7) the apparent threshold energy for the Al signal was higher than that for the Mg signal. The differences between the results for the two metals are attributed to the fact that the Al 2p orbital lies deeper in energy and closer to the nucleus than the corresponding Mg orbital.

  5. H, He, Ne, Ar-bombardment of amorphous hydrocarbon structures

    NASA Astrophysics Data System (ADS)

    Trskelin, P.; Nordlund, K.; Keinonen, J.

    2006-10-01

    Amorphous hydrogenated carbon films have found various applications due to the unique combination of properties of this material. In tokamak-like fusion reactors, this material is subject to bombardment primarily by H, but also to smaller amounts of noble gas ions. The effect of these low energy noble gas ions on the erosion of carbon is however not known. In this work, both cumulative and non-cumulative bombardment simulations were performed of hydrogen, helium, neon, and argon ions impinging onto a-C:H surfaces at energies ranging from 2 to 10 eV, employing a reactive hydrocarbon potential model. At noble gas/hydrogen ratios of 1/10 we saw no significant difference between the sputtering yields obtained from the bombardment simulations of different noble gas ions. A marked difference in the surface morphology was, however, observed between the final simulation cells from the 5 eV and the 10 eV ion bombardment simulations.

  6. Prevention of cathode damage from positive ion bombardment

    NASA Technical Reports Server (NTRS)

    Bennett, W. H.

    1972-01-01

    Mixed alkaline earth oxide compounds deposited into hole at cathode surface center prevent ion back bombardment damage to cathode by reducing oxide layer and by creating metallic diffusion along sides of hole for enhanced electron emission.

  7. Synthetic chemistry with fullerenes. Photooxygenation of olefins

    SciTech Connect

    Tokuyama, Hidetoshi; Nakamura, Eiichi

    1994-03-11

    Under irradiation with visible or UV (>290 nm) light in the presence of molecular oxygen and a minute amount of fullerenes, olefins and dienes undergo ene and Diels-Alder reactions with singlet oxygen to give photooxygenation products. The regio-and stereoselectives of the photooxygenation of {beta}-myrcene, (+)-pulegone, 4-methylpent-3-en-2-ol, and (+)-limonene were very similiar to those observed in known singlet oxygen reactions, indicating that the fullerene-sensitized reaction generates free singlet oxygen. The efficiency of fullerenes and conventional sensitizers was qualitively examined by using the Diels-Alder reaction between {sup 1}O{sub 2} and furan-2-carboxylic acid as a probe. Among those examined, C{sub 70} was found to be the most effective. The reaction was the fastest and completed with as little as 0.0001 equiv of C{sub 70}. C{sub 60} and hematoporphyrin were found to be of similiar efficiency. The methanofullerene 13, which lacks one olefinic conjunction in the C{sub 60} core, was as good as C{sub 60} itself, but the aminofullerene 14, lacking six double bonds, was quite inferior. The fullerene carboxylic acid 15, which was previously shown to show considerable biochemical activity, was found to be capable of generating singlet oxygen in aqueous DMSO. 25 refs., 1 tab.

  8. Arranging pseudorotaxanes octahedrally around 60 fullerene

    SciTech Connect

    Dey, Sanjeev K.; Beurele, Florian; Olson, Mark A.; Stoddart, J. Fraser

    2010-01-01

    The formation of both [2]- and [7]pseudorotaxanes, which are obtained by mixing of a dibenzylammonium derivative with mono- and hexakis-adducts of [60]fullerene bearing malonato-benzo[25]crown-8 rings, has been monitored in dichloromethane by both 1D and 2D H NMR spectroscopies.

  9. Inorganic nanotubes and fullerene-like nanoparticles

    NASA Astrophysics Data System (ADS)

    Tenne, R.

    2006-11-01

    Although graphite, with its anisotropic two-dimensional lattice, is the stable form of carbon under ambient conditions, on nanometre length scales it forms zero- and one-dimensional structures, namely fullerenes and nanotubes, respectively. This virtue is not limited to carbon and, in recent years, fullerene-like structures and nanotubes have been made from numerous compounds with layered two-dimensional structures. Furthermore, crystalline and polycrystalline nanotubes of pure elements and compounds with quasi-isotropic (three-dimensional) unit cells have also been synthesized, usually by making use of solid templates. These findings open up vast opportunities for the synthesis and study of new kinds of nanostructures with properties that may differ significantly from the corresponding bulk materials. Various potential applications have been proposed for the inorganic nanotubes and the fullerene-like phases. Fullerene-like nanoparticles have been shown to exhibit excellent solid lubrication behaviour, suggesting many applications in, for example, the automotive and aerospace industries, home appliances, and recently for medical technology. Various other potential applications, in catalysis, rechargeable batteries, drug delivery, solar cells and electronics have also been proposed.

  10. Manipulation of fullerene molecules on graphene

    NASA Astrophysics Data System (ADS)

    Glukhova, O. E.; Mitrofanov, V. V.; Slepchenkov, M. M.; Shunaev, V. V.

    2015-03-01

    Due to the increasing demand for functionalization of graphene and its application as a functional element of real electronic and / or mechanical devices, as well as due to its unique adhesive and sensory abilities the actual problem is the use of graphene as a substrate on which the assembly of supramolecular structures. Elements of such structures can be different molecules driven by external factors, and can be easily transported on graphene. These molecules primarily include miniature spheroidal fullerenes easy to navigate on the surface of graphene, in particular icosahedral C60. The aim of this work was to find an effective method of manipulation of fullerene C60 on graphene. As such method we proposed to introduce in graphene sheet structural defect of the atomic framework namely defect Stone-Wales (pentagon-heptagon pairs). Another structural defect studied in this paper is adsorbed on the Stone-Wales defect hydrogen atom. Molecular dynamics and tight binding method were applied to calculate the location of the molecule C60 on graphene sheet and its movement. To identify the regulatities of behavior of fullerene on graphene sheet we carried out a series of numerical experiments at different temperatures. In this paper we calculated the energy profile of interaction between fullerene and graphene sheet. Obtained results showed that forming on the surface of the graphene sheet defects in a certain way, one can control the trajectory of molecules on graphene.

  11. C60 fullerene binding to DNA

    NASA Astrophysics Data System (ADS)

    Alshehri, Mansoor H.; Cox, Barry J.; Hill, James M.

    2014-09-01

    Fullerenes have attracted considerable attention in various areas of science and technology. Owing to their exceptional physical, chemical, and biological properties, they have many applications, particularly in cosmetic and medical products. Using the Lennard-Jones 6-12 potential function and the continuum approximation, which assumes that intermolecular interactions can be approximated by average atomic surface densities, we determine the binding energies of a C60 fullerene with respect to both single-strand and double-strand DNA molecules. We assume that all configurations are in a vacuum and that the C60 fullerene is initially at rest. Double integrals are performed to determine the interaction energy of the system. We find that the C60 fullerene binds to the double-strand DNA molecule, at either the major or minor grooves, with binding energies of -4.7 eV or -2.3 eV, respectively, and that the C60 molecule binds to the single-strand DNA molecule with a binding energy of -1.6 eV. Our results suggest that the C60 molecule is most likely to be linked to the major groove of the dsDNA molecule.

  12. Carbon-Sublimation Production of Fullerenes.

    NASA Astrophysics Data System (ADS)

    Tinker, Frank Albert

    1995-01-01

    Carbon-sublimation production of fullerenes enjoys wide use in both experimental and industrial application worldwide. Although it has been nearly five years since the inception of the technique, little is known about the roles various parameters play in the production process. This work attempts to shed light, both experimentally and theoretically, on the basic processes at work in this type of fullerene production. Experimental results herein show that a functional relationship exists among the C_{60 }, C_{70}, C_{76}, C_ {78}, and C_{84} fullerenes produced in carbon arcs. This result is interpreted to mean that an equilibrium description of the production process may be valid. Theoretical calculations are then offered in support of such a view. The theory goes on to show details of an equilibrium description that reproduce essential features of fullerene mass-spectra. It is shown that equilibrium abundances of n-atom -sized clusters are highly dependent on the stoichiometric equation chosen to describe the system. However, common traits of the investigated equilibrium descriptions lead to useful conclusions.

  13. Monitoring of Aqueous Fullerene Dispersions by Thermal-Lens Spectrometry

    NASA Astrophysics Data System (ADS)

    Mikheev, I. V.; Volkov, D. S.; Proskurnin, M. A.; Korobov, M. V.

    2015-06-01

    Aqueous fullerene solutions (dispersions) are very promising materials of biomedicine and biotechnology. Of importance are the traceability of their production and characterization of their optical and colloidal properties. Thermal-lens spectrometry, as a method suitable for both optical and thermophysical studies, was used to elucidate the forms of non-modified fullerenes in their aqueous dispersions and to determine low concentrations of and fullerenes. It was shown that the residual amounts of toluene in aqueous fullerene dispersions made according to the solvent-exchange protocol could be detected by thermal lensing. As a result, the technique for the production of aqueous fullerene dispersions was improved compared to the existing data providing higher fullerene concentrations. The limits of detection of and fullerenes are approximately , which are 20-fold lower compared to conventional spectrophotometry. The distinction between aqueous fullerene dispersions in comparison with organic solutions of fullerenes caused by the formation of large clusters is shown by the comparison of transient and steady-state calibration curves for aqueous and organic fullerene solutions and model reference systems under various thermal-lens excitation conditions. The advantages of thermal lensing for such colloidal systems are discussed.

  14. Bombardment-induced segregation and redistribution

    SciTech Connect

    Lam, N.Q.; Wiedersich, H.

    1986-04-01

    During ion bombardment, a number of processes can alter the compositional distribution and microstructure in near-surface regions of alloys. The relative importance of each process depends principally on the target composition, temperature, and ion characteristics. In addition to displacement mixing leading to a randomization of atomic locations, and preferential loss of alloying elements by sputtering, which are dominant at relatively low temperatures, several thermally-activated processes, including radiation-enhanced diffusion, radiation-induced segregation and Gibbsian adsorption, also play important roles. At elevated temperatures, nonequilibrium point defects induced by ion impacts become mobile and tend to anneal out by recombination and diffusion to extended sinks, such as dislocations, grain boundaries and free surfaces. The high defect concentrations, far exceeding the thermodynamic equilbrium values, can enhance diffusion-controlled processes, while persistent defect fluxes, originating from the spatial non-uniformity in defect production and annihilation, give rise to local redistribution of alloy constituents because of radiation-induced segregation. Moreover, when the alloy is maintained at high temperature, Gibbsian adsorption, driven by the reduction in free energy of the system, occurs even without irradiation; it involves a compositional perturbation in a few atom layers near the alloy surface. The combination of these processes leads to the complex development of a compositionally-modified layer in the subsurface region. In the present paper, selected examples of these different phenomena and their synergistic effects on the evolution of the near-surface compositions of alloys during sputtering and ion implantation at elevated temperatures are discussed. 74 refs., 7 figs., 1 tab.

  15. Search for fullerenes in stone meteorites

    NASA Astrophysics Data System (ADS)

    Oester, M. Y.; Kuechl, D.; Sipiera, P. P.; Welch, C. J.

    1994-07-01

    The possibility of identifying fullerenes in stony meteorites became apparent from a paper given by Radicati de Brozolo. In this paper it was reported that fullerenes were present in the debris resulting from a collision between a micrometeoroid and an orbiting satellite. This fact generated sufficient curiosity to initiate a search for the presence of fullerenes in various stone meteorites. In the present study seven ordinary chondrites (al-Ghanim L6 (find), Dimmitt H4 (find), Lazbuddie LL5 (find), New Concord H5 (fall), Silverton H4 (find), Springlake L6 (find), and Umbarger L3/6 (find)). Four carbonaceous chondrites (ALH 83100 C2 (find), ALH 83108 C30 (find), Allende CV3 (fall), and Murchison CM2 (fall), and one achondrite (Monticello How (find)) were analyzed for the presence of fullerenes. The analytical procedure employed was as follows: 100 mg of meteorite was ground up with a mortar and pestle; 10 mL of toluene was then added and the mixture was refluxed for 90 min; this mixture was then filtered through a short column of silica; a 50 microliter sample was then analyzed by high pressure liquid chromatography (HPLC) using a Buckyclutcher I column with a mobile phase consisting of equal volumes of toluene and hexane at a flow rate of 1.00 mg per minute, with detection at 330 and 600 nm. Three of the meteorites, Allende, Murchison, and al-Ghanim, gave HPLC traces containing peaks with similar retention times to the HPLC trace of an authentic fullerene C60. However, further analysis using an HPLC instrument equipped with a diode-array detector failed to confirm any of the substances detected in the three meteorites as C60. Additional analyses will be conducted to identify what the HPLC traces actually represent.

  16. Thermal transport in C20 fullerene-chained carbon nanobuds

    NASA Astrophysics Data System (ADS)

    Loh, G. C.; Baillargeat, D.

    2013-03-01

    Carbon nanobuds, which are hybrid fullerene-nanotube structures, have previously shown glimpses of their potential in nanotechnology applications. By performing molecular dynamics simulations, a novel study of thermal conduction in a compact form of carbon nanobuds is presented. We demonstrate that nanobuds conduct thermal energy relatively well, within an order compared to nanotubes. Alike their close relativesthe carbon peapod, this essentially extends the dimensionality of thermal management applications. A rigorous calculation of the vibrational entropy and specific heat at the interfacial locations suggests that both functions are relatively identical in magnitude at fullerene-fullerene and fullerene-nanotube interfaces. Two common nanobud configurations are compared: while both are comparable in mechanical stability, a type 2 carbon nanobud (perfect fullerene, nanotube with vacancies) is less thermally conductive than a type 1 nanobud (perfect fullerene, perfect nanotube) due to more scattering of long-wavelength modes at the defect sites of the nanotube.

  17. Study of endohedral doped C60 fullerene using model potentials

    NASA Astrophysics Data System (ADS)

    Umran, N. M.; Kaur, Narinder; Seema, K.; Kumar, Ranjan

    2015-05-01

    In this paper, we present a study of Si, Ge, Au and Tl doped endohedral fullerenes using model potentials. We have used Brenner potential, Lennard-Jones potential and Gupta potential to describe the C-C (Si, Ge), C-metal and metal-metal interaction, respectively. We have done total energy calculations to find out the minimum energy structures. In the case of Sin@C60 complex, a maximum of nine atoms can be doped inside the fullerene cage. The addition of a tenth Si atom leads to the breaking of the fullerene cage. Similarly for Ge, Au and Tl, a maximum of four, two and two atoms, respectively, can be doped inside the fullerene cage. It has been observed that the stability of fullerene decreases with an increase in the number of dopant atoms. These calculations prove the change of characteristics of fullerenes upon doping.

  18. Biological activities of water-soluble fullerene derivatives

    NASA Astrophysics Data System (ADS)

    Nakamura, S.; Mashino, T.

    2009-04-01

    Three types of water-soluble fullerene derivatives were synthesized and their biological activities were investigated. C60-dimalonic acid, an anionic fullerene derivative, showed antioxidant activity such as quenching of superoxide and relief from growth inhibition of E. coli by paraquat. C60-bis(7V,7V-dimethylpyrrolidinium iodide), a cationic fullerene derivative, has antibacterial activity and antiproliferative effect on cancer cell lines. The mechanism is suggested to be respiratory chain inhibition by reactive oxygen species produced by the cationic fullerene derivative. Proline-type fullerene derivatives showed strong inhibition activities on HIV-reverse transcriptase. The IC50 values were remarkably lower than nevirapine, a clinically used anti-HIV drug. Fullerene derivatives have a big potential for a new type of lead compound to be used as medicine.

  19. Recent progresses in application of fullerenes in cosmetics.

    PubMed

    Lens, Marko

    2011-08-01

    Cosmetic industry is a fast growing industry with the continuous development of new active ingredients for skin care products. Fullerene C(60) and its derivates have been subject of intensive research in the last few years. Fullerenes display a wide range of different biological activities. Strong antioxidant capacities and effective quenching radical oxygen species (ROS) made fullerenes suitable active compounds in the formulation of skin care products. Published evidence on biological activities of fullerenes relevant for their application in cosmetics use and examples of published patents are presented. Recent trends in the use of fullerenes in topical formulations and patents are reviewed. Future investigations covering application of fullerenes in skin care are discussed. PMID:21619548

  20. Memory operation mechanism of fullerene-containing polymer memory

    SciTech Connect

    Nakajima, Anri Fujii, Daiki

    2015-03-09

    The memory operation mechanism in fullerene-containing nanocomposite gate insulators was investigated while varying the kind of fullerene in a polymer gate insulator. It was cleared what kind of traps and which positions in the nanocomposite the injected electrons or holes are stored in. The reason for the difference in the easiness of programming was clarified taking the role of the charging energy of an injected electron into account. The dependence of the carrier dynamics on the kind of fullerene molecule was investigated. A nonuniform distribution of injected carriers occurred after application of a large magnitude programming voltage due to the width distribution of the polystyrene barrier between adjacent fullerene molecules. Through the investigations, we demonstrated a nanocomposite gate with fullerene molecules having excellent retention characteristics and a programming capability. This will lead to the realization of practical organic memories with fullerene-containing polymer nanocomposites.

  1. Fullerenes: an extraterrestrial carbon carrier phase for noble gases.

    PubMed

    Becker, L; Poreda, R J; Bunch, T E

    2000-03-28

    In this work, we report on the discovery of naturally occurring fullerenes (C60 to C400) in the Allende and Murchison meteorites and some sediment samples from the 65 million-year-old Cretaceous/Tertiary boundary layer (KTB). Unlike the other pure forms of carbon (diamond and graphite), fullerenes are extractable in an organic solvent (e.g., toluene or 1,2,4-trichlorobenzene). The recognition of this unique property led to the detection and isolation of the higher fullerenes in the Kratschmer/Huffmann arc evaporated graphite soot and in the carbon material in the meteorite and impact deposits. By further exploiting the unique ability of the fullerene cage structure to encapsulate and retain noble gases, we have determined that both the Allende and Murchison fullerenes and the KTB fullerenes contain trapped noble gases with ratios that can only be described as extraterrestrial in origin. PMID:10725367

  2. Fullerenes: An extraterrestrial carbon carrier phase for noble gases

    PubMed Central

    Becker, Luann; Poreda, Robert J.; Bunch, Ted E.

    2000-01-01

    In this work, we report on the discovery of naturally occurring fullerenes (C60 to C400) in the Allende and Murchison meteorites and some sediment samples from the 65 million-year-old Cretaceous/Tertiary boundary layer (KTB). Unlike the other pure forms of carbon (diamond and graphite), fullerenes are extractable in an organic solvent (e.g., toluene or 1,2,4-trichlorobenzene). The recognition of this unique property led to the detection and isolation of the higher fullerenes in the Kratschmer/Huffmann arc evaporated graphite soot and in the carbon material in the meteorite and impact deposits. By further exploiting the unique ability of the fullerene cage structure to encapsulate and retain noble gases, we have determined that both the Allende and Murchison fullerenes and the KTB fullerenes contain trapped noble gases with ratios that can only be described as extraterrestrial in origin. PMID:10725367

  3. Optical limiting processes in derivatized fullerenes and porphyrins/phthalocyanines

    SciTech Connect

    Kohlman, R.; Klimov, V.; Shi, X.

    1998-07-01

    The authors review their results from spectral studies of the ultrafast excited-state absorption in fullerenes and derivatized fullerenes. These results allow determination of both the spectral response of reverse saturable absorption (RSA) nonlinearities such as optical limiting (OL) in fullerenes, and the dynamical response for different morphologies. The authors have investigated the effects of thin film and various sol-gel glass environments on the nanosecond OL and femtosecond dynamics of derivatized fullerenes. These data provide evidence of decay pathways which compete with the intersystem crossing to a triplet from the initial singlet states. With appropriate processing, however, the OL response of derivatized-fullerene sol-gel glasses can be enhanced to approach that of the same molecule in solution, while significantly enhancing the optical damage threshold. The optical limiting of these derivatized fullerenes is compared with that of various porphyrin and phthalocyanine molecules.

  4. M Sub-Shell Cross Sections For 75-300 keV Proton Impact On W, Pt And Pb

    SciTech Connect

    Cipolla, Sam J.

    2011-06-01

    M sub-shell x-ray production cross sections from 75-300 keV proton bombardment of thick elemental targets of W, Pt, and Pb were measured and compared with ECPSSR and relativistic RPWBA-BC cross sections using different data bases of fluorescence yields, Coster-Kronig factors, and x-ray transition rates. With a few exceptions, the differences between the various data base comparisons were not significant. For different sub-shells, either ECPSSR or RPWBA-BC compared better with the measurements. In all cases, agreement with theory improved as the collision energy increased.

  5. Is low-energy-ion bombardment generated X-ray emission a secondary mutational source to ion-beam-induced genetic mutation?

    NASA Astrophysics Data System (ADS)

    Thongkumkoon, P.; Prakrajang, K.; Thopan, P.; Yaopromsiri, C.; Suwannakachorn, D.; Yu, L. D.

    2013-07-01

    Low-energy ion beam biotechnology has achieved tremendous successes in inducing crop mutation and gene transfer. However, mechanisms involved in the related processes are not yet well understood. In ion-beam-induced mutation, ion-bombardment-produced X-ray has been proposed to be one of the secondary mutation sources, but the speculation has not yet been experimentally tested. We carried out this investigation to test whether the low-energy ion-beam-produced X-ray was a source of ion-beam-induced mutation. In the investigation, X-ray emission from 29-keV nitrogen- or argon- ion beam bombarded bacterial Escherichia coli (E. coli) cells held in a metal or plastic sample holder was in situ detected using a highly sensitive X-ray detector. The ion beam bombarded bacterial cells held in different material holders were observed for mutation induction. The results led to a conclusion that secondary X-ray emitted from ion-beam-bombarded biological living materials themselves was not a, or at least a negligible, mutational source, but the ion-beam-induced X-ray emission from the metal that made the sample holder could be a source of mutation.

  6. Protective Fullerene (C60) Packaging System for Microelectromechanical Systems Applications

    NASA Technical Reports Server (NTRS)

    Olivas, John D. (Inventor)

    2001-01-01

    The invention involves a method for locating the probe of a scanning tunneling micrograph a predetermined distance from its conducting surface, and specifically the deposition of a monolayer of fullerene C60 onto the conducting plate. The Fullerene C60 molecule is approximately spherical and a monolayer of fullerene has a thickness of one nanometer. By providing a monolayer of fullerene on the conducting surface and locating the probe on the surface of the monolayer, a distance of one nanometer can be established between the probe tip and the conducting surface.

  7. Higher fullerenes: Compositional analysis by EDXD and molecular dynamics

    SciTech Connect

    Carbone, Marilena; Gontrani, Lorenzo

    2014-06-19

    A carbon soot of higher fullerenes was studied by Energy Dispersive X-ray Diffraction (EDXD) aiming at defining the overall structure as accurately as possible to define the overall structure, without lengthy separation and purification procedures. EDXD pattern was compared with model curves obtained for single homogeneous fullerenes already crystallized and for the hypothesized C180. All fullerenes contribute to the overall experimental curve to different extents, with C96 giving the best agreement. The presence of even higher fullerenes is very likely, since the hypothesized C180 gives a very good match as well.

  8. Polymer-fullerene composite solar cells.

    PubMed

    Thompson, Barry C; Frchet, Jean M J

    2008-01-01

    Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Polymer-based organic photovoltaic systems hold the promise for a cost-effective, lightweight solar energy conversion platform, which could benefit from simple solution processing of the active layer. The function of such excitonic solar cells is based on photoinduced electron transfer from a donor to an acceptor. Fullerenes have become the ubiquitous acceptors because of their high electron affinity and ability to transport charge effectively. The most effective solar cells have been made from bicontinuous polymer-fullerene composites, or so-called bulk heterojunctions. The best solar cells currently achieve an efficiency of about 5%, thus significant advances in the fundamental understanding of the complex interplay between the active layer morphology and electronic properties are required if this technology is to find viable application. PMID:18041798

  9. A dendritic fullerene-porphyrin dyad.

    PubMed

    Campidelli, Stphane; Deschenaux, Robert; Swartz, Angela; Rahman, G M Aminur; Guldi, Dirk M; Milic, Dragana; Vzquez, Ester; Prato, Maurizio

    2006-12-01

    We describe the synthesis, characterization and photophysical properties of a fullerene derivative whose structure includes a Zn-porphyrin and a second generation liquid-crystalline (LC) dendrimer. The size of the fullerene and porphyrin units with respect to the size of the LC dendrimer prevents the formation of liquid-crystalline phases. However, this system gives interesting photoinduced electron transfer phenomena. Compound has been investigated by steady state and time resolved fluorescence as well as transient absorption spectroscopy in polar and apolar solvents. We demonstrate that the fluorescence of the porphyrin unit in is quenched compared to the Zn-tetraphenylporphyrin used as reference. Femto- and picosecond transient absorption permit to identify the formation of a radical ion pair while nanosecond experiments allowed the determination of the charge recombination lifetimes. PMID:17136279

  10. Carbon and fullerene nanomaterials in plant system

    PubMed Central

    2014-01-01

    Both the functionalized and non functionalized carbon nanomaterials influence fruit and crop production in edible plants and vegetables. The fullerene, C60 and carbon nanotubes have been shown to increase the water retaining capacity, biomass and fruit yield in plants up to ~118% which is a remarkable achievement of nanotechnology in recent years. The fullerene treated bitter melon seeds also increase the phytomedicine contents such as cucurbitacin-B (74%), lycopene (82%), charantin (20%) and insulin (91%). Since as little as 50?gmL?1 of carbon nanotubes increase the tomato production by about 200%, they may be exploited to enhance the agriculture production in future. It has been observed that, in certain cases, non functionalized multi-wall carbon nanotubes are toxic to both plants and animals but the toxicity can be drastically reduced if they are functionalized. PMID:24766786

  11. Preparation of fullerene/glass composites

    DOEpatents

    Mattes, B.R.; McBranch, D.W.; Robinson, J.M.; Koskelo, A.C.; Love, S.P.

    1995-05-30

    Synthesis of fullerene/glass composites is described. A direct method for preparing solid solutions of C{sub 60} in silicon dioxide (SiO{sub 2}) glass matrices by means of sol-gel chemistry is described. In order to produce highly concentrated fullerene-sol-gel-composites it is necessary to increase the solubility of these ``guests`` in a delivery solvent which is compatible with the starter sol (receiving solvent). Sonication results in aggregate disruption by treatment with high frequency sound waves, thereby accelerating the rate of hydrolysis of the alkoxide precursor, and the solution process for the C{sub 60}. Depending upon the preparative procedure, C{sub 60} dispersed within the glass matrix as microcrystalline domains, or dispersed as true molecular solutions of C{sub 60} in a solid glass matrix, is generated by the present method.

  12. Preparation of fullerene/glass composites

    DOEpatents

    Mattes, Benjamin R.; McBranch, Duncan W.; Robinson, Jeanne M.; Koskelo, Aaron C.; Love, Steven P.

    1995-01-01

    Synthesis of fullerene/glass composites. A direct method for preparing solid solutions of C.sub.60 in silicon dioxide (SiO.sub.2) glass matrices by means of sol-gel chemistry is described. In order to produce highly concentrated fullerene-sol-gel-composites it is necessary to increase the solubility of these "guests" in a delivery solvent which is compatible with the starter sol (receiving solvent). Sonication results in aggregate disruption by treatment with high frequency sound waves, thereby accelerating the rate of hydrolysis of the alkoxide precursor, and the solution process for the C.sub.60. Depending upon the preparative procedure, C.sub.60 dispersed within the glass matrix as microcrystalline domains, or dispersed as true molecular solutions of C.sub.60 in a solid glass matrix, is generated by the present method.

  13. An Elastic Continuum Model for Fullerene Energetics

    NASA Astrophysics Data System (ADS)

    Xiaoyu, Xia; Ji-Xing, Liu; Zhong-Can, Ou-Yang

    By analogy with the elastic theory of solid shells1 and fluid membranes,2 it has been suggested that fullerenes, at least large ones, might somehow resemble the classic elastic continuum, as indicated by Schnur.3 Some related works dealt with nanotubes do show positive evidence for this suggestion.4 Here we propose an elastic continuum model appropriate to graphite-like networks. Applying it to various shapes of fullerenes, such as spheres, tubes, tori, and minimal surfaces, we found good agreement between this model and previous numerical results given by approaches of ab initio or empirical potential. Furthermore, this model enables one to understand the puzzling phenomena such as why Schwarzite P216 and Schwarzite D216 have nearly identical bending energies while their geometric forms are very different (see Fig. 1). The prospect of this model is also discussed.

  14. Passive optical switches based on endohedral fullerenes

    NASA Astrophysics Data System (ADS)

    Dong, Yongchang; Saini, Deepika; Echegoyen, Luis A.; Podila, Ramakrishna

    2016-03-01

    Reverse saturable absorption in fullerenes has been widely used to realize excellent passive optical limiters for the visible region up to 650 nm. However, there is still a need for passive optical switches and limiters with a low limiting threshold (<0.5 J/cm2) and higher damage limits. The electronic structure of fullerenes can be modified either through doping or by the encapsulation of endohedral clusters to achieve exotic quantum states of matter such as superconductivity. Building on this ability, we show that the encapsulation of Sc3N, Lu3N or Y3N in C80 alters the HOMO-LUMO gap and leads to passive optical switches with a significantly low limiting threshold (0.3 J/cm2) and a wider operation window (average pulse energy >0.3 mJ in the ns regime).

  15. Phase transition, formation and fragmentation of fullerenes

    NASA Astrophysics Data System (ADS)

    Hussien, A.; Yakubovich, A. V.; Solov'yov, A. V.; Greiner, W.

    2010-04-01

    We present a statistical mechanics model treating the formation and the fragmentation of fullerenes as a phase transition. Based on this model, we investigate the formation and fragmentation of C60 and C240 fullerenes from and to a gas of carbon dimers by means of molecular dynamics (MD) simulations. These simulations were conducted for 500 ns using a topologically-constrained forcefield. At the phase transition temperature, both the cage and gaseous phases were found to coexist and the system continuously oscillates between the two phases. Combining the results of the MD simulations and the statistical mechanics approach, we obtain the dependence of the phase transition temperature on pressure and compare the results of our model with arc-discharge experiments.

  16. Delayed Ionization of Fullerenes and Fullerene Derivatives upon Laser Desorption and Surface Collision

    NASA Astrophysics Data System (ADS)

    Beck, R. D.; Weis, P.; Rockenberger, J.; Kappes, M. M.

    Delayed electron emission has been observed upon laser desorption for several fullerenes, endohedral metallofullerenes, and large carbon clusters formed by coalescence reactions. Odd-numbered carbon clusters and fullerene derivatives with exohedral functional groups do not show delayed ionization under similar conditions, presumably due to lower dissociation energies. Thus, delayed electron emission is suggested to be a characteristic indicator for strongly bound fullerene structures. Measurements of the rate of delayed electron emission are used together with structural information from other sources to calculate ionization potentials for these species. Selective observation of delayed electron emission from scattered {C}60* after surface impact and neutralization of {C}+{60 on graphite confirms an earlier report of this process by Whetten et al.6

  17. Color-tunable photoluminescent fullerene nanoparticles.

    PubMed

    Jeong, Jinyoung; Jung, Juyeon; Choi, Mijin; Kim, Ju Whan; Chung, Sang J; Lim, Sujin; Lee, Han; Chung, Bong Hyun

    2012-04-17

    Highly water-soluble and color-tunable photoluminescent fullerene nanoparticles are synthesized by using tetraethylene glycol (TEG) and lithium hydroxide as a catalyst. The maximum PL emission changes depend on the contents of the remaining ?-conjugation in oxidized C(60), which is partially covalently conjugated with TEG. The PL behavior is attributed to an electronic transition change due to the distortion of symmetrical C(60). PMID:22431377

  18. Optical limiting materials based on fullerene derivatives

    SciTech Connect

    Prato, Maurizio; Maggini, Michele; Scorrano, Gianfranco; Brusatin, Giovanna; Guglielmi, Massimo; Meneghetti, Moreno; Signorini, Raffaella; Bozio, Renato; Guldi, Dirk M.

    1999-09-30

    A functionalized fulleropyrrolidine has been synthesized and investigated for optical limiting applications. Solid materials have been prepared for optical limiting devices by incorporation in sol-gel glasses. Their nonlinear transmission properties have been measured and found comparable with those of solution samples. We show that clustering of the fullerene spheres, which might affect the optical limiting properties, is not relevant. Multilayer structures following a bottleneck design are prepared and their NL transmission properties are characterized. (c) 1999 American Institute of Physics.

  19. Fullerene derivatives with increased dielectric constants.

    PubMed

    Jahani, Fatemeh; Torabi, Solmaz; Chiechi, Ryan C; Koster, L Jan Anton; Hummelen, Jan C

    2014-09-21

    The invention of new organic materials with high dielectric constants is of extreme importance for the development of organic-based devices such as organic solar cells. We report on a synthetic way to increase the dielectric constant of fullerene derivatives. It is demonstrated that introducing triethylene glycol monoethyl ether (teg) side chains into fulleropyrrolidines increases the dielectric constant by ~46 percent without devaluation of optical properties, electron mobility and the energy level of the compound. PMID:25075465

  20. Highly hydroxide conductive ionomers with fullerene functionalities.

    PubMed

    Yang, Zhengjin; Liu, Yazhi; Guo, Rui; Hou, Jianqiu; Wu, Liang; Xu, Tongwen

    2016-02-01

    A novel ionomer was designed that will not poison the catalyst in alkaline fuel cells, by incorporating for the first time N-methyl pyrrolidine-C60 cation in polymeric anion exchange ionomers. The resultant fullerene-based anion exchange ionomer shows an extremely high hydroxide conductivity (182 mS cm(-1)) at a low cation concentration (0.62 mmol g(-1)). PMID:26765494

  1. Diamond films grown from fullerene precursors

    SciTech Connect

    Gruen, D.M.; Zuiker, C.D.; Krauss, A.R.

    1995-07-01

    Fullerene precursors have been shown to result in the growth of diamond films from argon microwave plasmas. In contradistinction to most diamond films grown using conventional methane-hydrogen mixtures, the fullerene-generated films are nanocrystalline and smooth on the nanometer scale. They have recently been shown to have friction coefficients approaching the values of natural diamond. It is clearly important to understand the development of surface morphology during film growth from fullerene precursors and to elucidate the factors leading to surface roughness when hydrogen is present in the chemical vapor deposition (CVD) gas mixtures. To achieve these goals, we are measuring surface reflectivity of diamond films growing on silicon substrates over a wide range of plasma processing conditions. A model for the interpretation of the laser interferometric data has been developed, which allows one to determine film growth rate, rms surface roughness, and bulk losses due to scattering and absorption. The rms roughness values determined by reflectivity are in good agreement with atomic force microscope (AFM) measurements. A number of techniques, including high-resolution transmission electron microscopy (HRTEM) and near-edge x-ray absorption find structure (NEXAFS) measurements, have been used to characterize the films. A mechanism for diamond-film growth involving the C{sub 2} molecule as a growth species will be presented. The mechanism is based on (1) the observation that the optical emission spectra of the fullerene- containing plasmas are dominated by the Swan bands of C{sub 2} and (2) the ability of C{sub 2} to insert directly into C-H and C-C bonds with low activation barriers, as shown by recent theoretical calculations of reactions of C{sub 2} with carbon clusters.

  2. PREFACE: Fullerene Nano Materials (Symposium of IUMRS-ICA2008)

    NASA Astrophysics Data System (ADS)

    Miyazawa, Kun'ichi; Fujita, Daisuke; Wakahara, Takatsugu; Kizuka, Tokushi; Matsuishi, Kiyoto; Ochiai, Yuichi; Tachibana, Masaru; Ogata, Hironori; Mashino, Tadahiko; Kumashiro, Ryotaro; Oikawa, Hidetoshi

    2009-07-01

    This volume contains peer-reviewed invited and contributed papers that were presented in Symposium N 'Fullerene Nano Materials' at the IUMRS International Conference in Asia 2008 (IUMRS-ICA 2008), which was held on 9-13 December 2008, at Nagoya Congress Center, Nagoya, Japan. Over twenty years have passed since the discovery of C60 in 1985. The discovery of superconductivity of C60 in 1991 suggested infinite possibilities for fullerenes. On the other hand, a new field of nanocarbon has been developed recently, based on novel functions of the low-dimensional fullerene nanomaterials that include fullerene nanowhiskers, fullerene nanotubes, fullerene nanosheets, chemically modified fullerenes, endohedral fullerenes, thin films of fullerenes and so forth. Electrical, electrochemical, optical, thermal, mechanical and various other properties of fullerene nanomaterials have been investigated and their novel and anomalous nature has been reported. Biological properties of fullerene nanomaterials also have been investigated both in medical applications and toxicity aspects. The recent research developments of fullerene nanomaterials cover a variety of categories owing to their functional diversity. This symposium aimed to review the progress in the state-of-the-art technology based on fullerenes and to offer the forum for active interdisciplinary discussions. 24 oral papers containing 8 invited papers and 22 poster papers were presented at the two-day symposium. Topics on the social acceptance of nanomaterials including fullerene were presented on the first day of the symposium. Biological impacts of nanomaterials and the importance of standardization of nanomaterials characterization were also shown. On the second day, the synthesis, properties, functions and applications of various fullerene nanomaterials were shown in both the oral and poster presentations. We are grateful to all invited speakers and many participants for valuable contributions and active discussions. This symposium was partly supported by the Coordination Program of Science and Technology Projects ''Developing Nanotechnologies and Engaging the Public'' conducted by the Council for Science and Technology Policy (CSTP) and funded by Special Coordination Funds for Promoting Science and Technology. Organizing committee of Symposium N (IUMRS-ICA 2008) Chair Kun'ichi Miyazawa (National Institute for Materials Science, Japan) Vice Chairs Daisuke Fujita (National Institute for Materials Science, Japan) Takatsugu Wakahara (National Institute for Materials Science, Japan) Tokushi Kizuka (Tsukuba University, Japan) Kiyoto Matsuishi (Tsukuba University, Japan) Yuichi Ochiai (Chiba University, Japan) Masaru Tachibana (Yokohama City University, Japan) Hironori Ogata (Hosei University, Japan) Tadahiko Mashino (Keio University, Japan) Ryotaro Kumashiro (Tohoku University, Japan) Hidetoshi Oikawa (Tohoku University, Japan)

  3. Magnetospheric ion bombardment profiles of satellites - Europa and Dione

    SciTech Connect

    Pospieszalska, M.K.; Johnson, R.E.

    1989-03-01

    Bombardment profiles generated by tracking ions in magnetospheric plasmas onto the surface of a satellite with a suitable description of the ion motion are used to calculate the spatial dependence across a satellite surface of the ion bombardment/implantation rate for satellites embedded in planetary magnetospheric plasmas. Attention is given to the results of a parameter study; a general dependency on ion gyroradius and pitch angle is noted, together with a strong dependence of access to the leading hemisphere on pitch-angle distribution. Gyromotion is found to cause differences in the bombardment of the inner and outer hemisphere. Reasonable speed and pitch-angle distributions are used to calculate profiles for sulfur ions incident on Europa and oxygen ones incident on Dione. 28 references.

  4. Magnetospheric ion bombardment profiles of satellites - Europa and Dione

    NASA Technical Reports Server (NTRS)

    Pospieszalska, M. K.; Johnson, R. E.

    1989-01-01

    Bombardment profiles generated by tracking ions in magnetospheric plasmas onto the surface of a satellite with a suitable description of the ion motion are used to calculate the spatial dependence across a satellite surface of the ion bombardment/implantation rate for satellites embedded in planetary magnetospheric plasmas. Attention is given to the results of a parameter study; a general dependency on ion gyroradius and pitch angle is noted, together with a strong dependence of access to the leading hemisphere on pitch-angle distribution. Gyromotion is found to cause differences in the bombardment of the inner and outer hemisphere. Reasonable speed and pitch-angle distributions are used to calculate profiles for sulfur ions incident on Europa and oxygen ones incident on Dione.

  5. Synthesis of fullerene-acene dyads

    NASA Astrophysics Data System (ADS)

    Cho, Claire Eunhye

    Organic photovoltaic (OPV) cells present potential for industrial use because of their possible low cost production. However, their relatively low efficiencies render them impractical for implementation. A comprehensive understanding of the photophysical process is necessary for eventual development of high efficiency OPV cells. Studying photophysical processes of well-defined structures such as dyad or triad molecules may give insight into their photophysical processes. In this study, we selected pentacene derivatives as electron donors and fullerenes as electron acceptors for dyad and triad molecules with well-defined structures. Several new types of organothiosubstituted 6,13-dihydropentacenes with terminal functionality including carboxylic acid, alcohol and amine groups were synthesized. A sterically hindered pentacene derivative was also prepared in order to prevent cycloaddition between C60 and pentacene. Functionalized fullerenes were synthesized for use as electron acceptors. Numerous reaction methods were attempted toward the synthesis of a donor/acceptor dyad with pentacene and fullerene derivatives. However, hydroamination of pristine C 60 using a diamino dihydropentacene derivative was the only successful method demonstrated to link C60 and dihydropentacene derivatives.

  6. Advances in Polymer-Fullerene Photovoltaic Devices

    NASA Astrophysics Data System (ADS)

    Heflin, James

    2011-10-01

    Polymer solar cells are of high interest due to their potential as efficient, lightweight, large area, flexible renewable energy sources. The basic mechanism for the photovoltaic effect in polymers consists of transfer of a photoexcited electron from the polymer donor to a fullerene electron acceptor followed by transport of the electron and hole through the acceptor and donor,, respectively, to the opposite electrodes. Polymer photovoltaic efficiencies can be increased by utilizing improved materials as electron donors and acceptors as well as by controlling the nanoscale morphology of the thin film devices. The highest efficiencies (7%) obtained thus far utilize a nanoscale polymer-fullerene blend referred to as a bulk heterojunction, which undergoes phase separation on the 10 nm length scale in order to facilitate charge transfer from the photoexcited polymer to the fullerene electron acceptor. More organized geometries that maximize the majority carrier materials at the respective electrodes could lead to enhanced efficiencies. In one approach, thermal interdiffusion of an initial bilayer of the donor and acceptor materials can be employed to create a concentration gradient in order to optimize both the charge transfer and charge transport processes. This presentation will overview the state-of-the-art in polymeric solar cells and describe the development of thermally-interdiffused concentration gradient geometries as an alternative route towards increased efficiencies.

  7. Fullerenes encaging metal clusters--clusterfullerenes.

    PubMed

    Yang, Shangfeng; Liu, Fupin; Chen, Chuanbao; Jiao, Mingzhi; Wei, Tao

    2011-11-21

    Clusterfullerenes represent a novel branch of endohedral fullerenes, which are characterized by a robust fullerene cage with metal clusters encaged in its hollow. Since the discovery of nitride clusterfullerenes (NCFs) in 1999, the family of clusterfullerenes has been significantly expanded within the past decade, with new members including carbide clusterfullerenes (CCFs), hydrocarbide clusterfullerenes (HCCFs), oxide clusterfullerenes (OCFs), sulfide clusterfullerenes (SCFs), and carbonitride clusterfullerenes (CNCFs). We first present the classification of clusterfullerenes and list all the clusterfullerenes reported to date. For each type of clusterfullerenes, we review in detail their synthesis, separation, intriguing molecular structures and properties. For NCFs, as the first and most important clusterfullerenes, we point out the significance of their discovery and focus on their new synthesis and separation methods as well as the new advances. Finally the potential applications of clusterfullerenes are addressed. We conclude that clusterfullerenes appear to be the fastest growing family of endohedral fullerenes up to now, and emphasize the importance of exploring new structures and chemical functionalizations of clusterfullerenes. PMID:21720619

  8. Effects of 70-keV electrons on two polyarylene ether ketones

    NASA Technical Reports Server (NTRS)

    Kingsbury, Kevin B.; Hawkins, Douglas S.; Orwoll, Robert A.; Kiefer, Richard L.; Long, Sheila A. T.

    1989-01-01

    Films prepared from two polyarylene ether ketones with the repeat units -PhC(O)PhC(O)-PhOPhXPhO- where X = C(CH3)2 or CH2 and Ph = C6H4, were bombarded with 70-keV electrons. The effects of irradiation were determined from the fraction of gel formed; the intrinsic viscosities, gel permeation chromatography, and NMR spectroscopy of the soluble portion of the irradiated films; and the changes in the IR spectra of the materials. In a Charlesby-Pinner analysis of the gel fractions of the polyarylene ether ketone with the isopropylidene group, the numbers of scission and cross-linking events per 100 eV (9649 kJ/mol) absorbed were found to be small with G(S) = 0.002 and G(X) = 0.009, respectively.

  9. 200 keV Xe+ ions irradiation effects on Zr-Ti binary films

    NASA Astrophysics Data System (ADS)

    Wang, Weipeng; Chai, Maosheng; Feng, Wei; Li, Zhengcao; Zhang, Zhengjun

    2015-05-01

    200 keV Xenon irradiation experiments were performed on magnetron sputtered Zr-Ti films under different doses up to 9 * 1015 ions/cm2. XRD, FE-SEM, AFM, HRTEM, nano-indentation and white light interferometer characterizations were applied to study the structural and mechanical properties modification introduced by the bombardment. Upon Xenon irradiation, structure of film matrix kept stable while the crystallinity of the top surface degraded significantly. Meanwhile, properties of irradiated films such as hardness, modulus and sheet resistance evolved with the same tendency, i.e. increased firstly and decrease with further increasing the irradiation dose. By selective area irradiation, competition between the surface sputtering and swelling was revealed, by which surface defects evolution was highlighted. The micro-defects evolution during Xenon irradiation was believed to be responsible for the macro-properties' modification.

  10. Formation of paramagnetic defects in oxide glasses during the bombardment of their surface with charged particles

    SciTech Connect

    Bogomolova, L.D.; Stefanovsky, S.V.; Teplyakov, Y.G.; Dmitriev, S.A.

    1997-12-31

    In the present work some results of EPR study of point defects formed in silicate, borate, borosilicate, phosphate and other oxide glasses irradiated with different charge particles (C, N, O, Ar, Mn, Cu, Pb) at energy E = 150 keV and large total fluence of ions (up to 10{sup 17} cm{sup {minus}2}) are reported. Electron paramagnetic resonance (EPR) is a very sensitive technique which gives information on the structure of point defects and their content. It is shown that in some cases (for example, in borate glasses) the oxygen hole centers similar to ones observed in {gamma}-irradiated glasses are formed after ion bombardment. However, in the majority of cases new defects which are not typical of {gamma}-irradiated oxide glasses were found. They were large molecular oxygen ions (O{sub 2}{sup {minus}}, O{sub 3}{sup {minus}}, O{sub 4}{sup {minus}}) located in the cavities formed under ion bombardment in the near surface layer of glass. It should be noted that the relative content of these defects is of the order of several tens per 1,000 incident ions. This content decreases with increasing fluence and atomic mass of incident ions. It indicates indirectly that point defects are clustered when the damage of the near surface layer becomes strong. The formation of gaseous oxygen is possible in cavities of the damage surface layer. It was found that some elements (for example C, N and transition metals) form chemical compounds with oxygen. The migration of alkali ions promotes the formation of such compounds since the chemical compounds were detected by means EPR in glasses rich in alkali oxides.

  11. Electron bombardment propulsion system characteristics for large space systems

    NASA Technical Reports Server (NTRS)

    Byers, D. C.; Rawlin, V. K.

    1976-01-01

    The results of an anlaysis of electron bombardment ion propulsion systems for use in the transportation and on-orbit operations of large space systems are presented. Using baseline technology from the ongoing primary propulsion program and other sources, preliminary estimates of the expected characteristics of key system elements such as thrusters and propellant storage systems were performed. Projections of expected thruster performance on argon are presented based on identified constraints which limit the achievable thrust and/or power density of bombardment thrusters. System characteristics are then evaluated as a function of thruster diameter and specific impulse.

  12. DDT_dgarciah_3: Searching for complex fullerene-based molecules in the prototype fullerene Planetary Nebula IC 418

    NASA Astrophysics Data System (ADS)

    García-Hernández, D. A.

    2013-02-01

    The recent and unexpected detection of the most common fullerenes (C60 and C70) and proto-graphene in some Planetary Nebulae (PNe) raises the exciting possibility that other more complex fullerene-based molecules (e.g., carbon onions or multishell fullerenes, fullerene-adducts) might be ubiquitous in the Universe and continue to be serious candidates to explain many astrophysical phenomena. The presence of complex fullerene-based molecules such as carbon onions in the circumstellar shells of fullerene-containing PNe is strongly suggested by our recent analysis of the unusual diffuse interstellar bands detected towards two PNe where C60 had already been found. If complex fullerene-based molecules such as carbon onions are present in this peculiar class of stars, they could easily be detected in the far-IR range. Fullerene-containing PNe are usually very faint in the far-IR but our very recent detection of C60 fullerenes in PN IC 418 can now mitigate this unfortunate situation. Surprisingly, Herschel has not observed this very bright source - now considered the prototype fullerene-containing PN - as part of any approved program in previous cycles. Thus, a comprehensive far-IR study of the complex circumstellar environment where fullerenes and fullerene-based molecules may form is at present lacking. With this DDT proposal we aim at obtaining full range, high S/N, Herschel/PACS far-IR spectra of PN IC 418 to search for the spectral signatures of complex fullerene-based molecules such as multishell fullerenes (e.g., C60@C240, C240@C960), which are predicted to be detectable as relatively strong broad features in the far-IR range. If successful, these observations will constitute the first firm detection of the most complex molecules ever detected in space. In addition, we will search for the predicted hydrogenated amorphous carbon (HAC) associated feature at ~60 um to confirm/refute the HAC's processing/decomposition scenario as the preferred fullerene formation route in PNe.

  13. Study on the keV neutron capture reaction in 56Fe and 57Fe

    NASA Astrophysics Data System (ADS)

    Wang, Taofeng; Lee, Manwoo; Kim, Guinyun; Ro, Tae-Ik; Kang, Yeong-Rok; Igashira, Masayuki; Katabuchi, Tatsuya

    2014-03-01

    The neutron capture cross-sections and the radiative capture gamma-ray spectra from the broad resonances of 56Fe and 57Fe in the neutron energy range from 10 to 90keV and 550keV have been measured with an anti-Compton NaI(Tl) detector. Pulsed keV neutrons were produced from the 7Li 7Be reaction by bombarding the lithium target with the 1.5ns bunched proton beam from the 3MV Pelletron accelerator. The incident neutron spectrum on a capture sample was measured by means of a time-of-flight (TOF) method with a 6Li -glass detector. The number of weighted capture counts of the iron or gold sample was obtained by applying a pulse height weighting technique to the corresponding capture gamma-ray pulse height spectrum. The neutron capture gamma-ray spectra were obtained by unfolding the observed capture gamma-ray pulse height spectra. To achieve further understanding on the mechanism of neutron radiative capture reaction and study on physics models, theoretical calculations of the -ray spectra for 56Fe and 57Fe with the POD program have been performed by applying the Hauser-Feshbach statistical model. The dominant ingredients to perform the statistical calculation were the Optical Model Potential (OMP), the level densities described by the Mengoni-Nakajima approach, and the -ray transmission coefficients described by -ray strength functions. The comparison of the theoretical calculations, performed only for the 550keV point, show a good agreement with the present experimental results.

  14. Fullerene C60: Surface Energy and Interfacial Interactions in Aqueous Systems

    EPA Science Inventory

    The underlying mechanisms of fullerene?fullerene, fullerene?water, and fullerene?soil surface interactions in aqueous systems are not well understood. To advance our understanding of these interfacial interactions, the surface properties of Buckminsterfullerene (C60) and quartz s...

  15. Sponge-like molecular cage for purification of fullerenes

    NASA Astrophysics Data System (ADS)

    Garca-Simn, Cristina; Garcia-Borrs, Marc; Gmez, Laura; Parella, Teodor; Osuna, Slvia; Juanhuix, Jordi; Imaz, Inhar; Maspoch, Daniel; Costas, Miquel; Ribas, Xavi

    2014-11-01

    Since fullerenes are available in macroscopic quantities from fullerene soot, large efforts have been geared toward designing efficient strategies to obtain highly pure fullerenes, which can be subsequently applied in multiple research fields. Here we present a supramolecular nanocage synthesized by metal-directed self-assembly, which encapsulates fullerenes of different sizes. Direct experimental evidence is provided for the 1:1 encapsulation of C60, C70, C76, C78 and C84, and solid state structures for the host-guest adducts with C60 and C70 have been obtained using X-ray synchrotron radiation. Furthermore, we design a washing-based strategy to exclusively extract pure C60 from a solid sample of cage charged with a mixture of fullerenes. These results showcase an attractive methodology to selectively extract C60 from fullerene mixtures, providing a platform to design tuned cages for selective extraction of higher fullerenes. The solid-phase fullerene encapsulation and liberation represent a twist in host-guest chemistry for molecular nanocage structures.

  16. Fullerenes Can Induce Toxic Physical Changes of DNA

    NASA Astrophysics Data System (ADS)

    Czerwinski, Fabian; Oddershede, Lene B.

    2008-03-01

    Fullerenes are fascinating symmetric carbon nanostructures. Nowadays, they are widely used because of their characteristic physical and chemical properties. Until now research has mainly been focused on commercial applications of fullerenes. Only a few investigations have addressed the potential biological hazards, one of which is that fullerenes are believed to alter the elastic properties of DNA upon binding. In our experiments we use optical tweezers with sub-piconewton and nanometer resolution to probe the structural changes and the potential damages which fullerenes might induce on single DNA molecules. Therefore, force-extension relations can be obtained under physiological conditions while varying the concentration of different types of fullerenes. It has theoretically been predicted [1], that certain fullerenes can function as a minor-groove binder to double-stranded DNA, thus altering its elastic properties significantly. Fullerenes are capable of causing severe damage inside living organisms by forming DNA regions which are not accessible for proper enzymatic functions. A further goal of the study is to establish fullerenes as a tool for a more detailed investigation of DNA-protein interactions, such as the trafficing of polymerases or the packing by procaryotic proteins. [1] Zhao X, Striolo A, and Cummings PT: C60 Binds to and Deforms Nucleotides. BiophysJ (89):3856-62, 2005.

  17. Three dimensional aromaticity, elemental boron and stuffed fullerenes

    SciTech Connect

    Jemmis, E.D.

    1994-12-31

    An intriguing aspect of fullerenes is the large empty space within. It has been possible to use this space as a molecular container encapsulating neutral atoms and metal ions. A few atoms do not fill the available space. To stuff fullerenes a systematic chemical binding of atoms or molecules to the endohedral surface is needed.

  18. Fullerene stability: One rule for the electron-rich...

    NASA Astrophysics Data System (ADS)

    Fowler, Patrick

    2015-11-01

    A vast number of possible isomers exist for each fullerene, yet few are observed experimentally. Neutral fullerenes typically minimize adjacent pentagons, but charged ones often tolerate them. Now, a simple model taking into account structural strain and ? electronic aspects predicts the asymmetric relative stabilities of charged isomers.

  19. Protective Fullerene (C60) Packaging System for Microelectromechanical Systems Applications

    NASA Technical Reports Server (NTRS)

    Olivas, John D. (Inventor)

    2004-01-01

    The invention involves tunneling tips to their conducting surface, and specifically the deposition of a monolayer of fullerene C60 onto the conducting plate surface to protect the tunneling tip from contact. The Fullerene C60 molecule is approximately spherical, and a monolayer of fullerene has a thickness of one nanometer, such that a monolayer thereby establishing the theoretical distance desired between the MEMS tunneling tip and the conducting plate. Exploiting the electrical conductivity of C60 the tip can be accurately positioned by simply monitoring conductivity between the fullerene and the tunneling tip. By monitoring the Conductivity between the tip and the fullerene layer as the tip is brought in proximity, the surfaces can be brought together without risk of contacting the underlying conducting surface. Once the tunneling tip is positioned at the one nanometer spacing, with only the monolayer of fullerene between the tunneling tip and the conducting plate, the monolayer of C60, can be broken down thermally and removed chemically leaving only the tunneling tip and the conducting plate at the ideal tunneling spacing. Alternatively, the properties of fullerene allow the tunneling process to occur directly across the fullerene monolayer.

  20. Fullerenes and Noble Gases in the Murchison and Allende Meteorites

    NASA Technical Reports Server (NTRS)

    Becker, Luann; Poreda, Robert J.; Bunch, Ted E.

    2000-01-01

    In this work we report the detection of fullerenes (C60 to C250) in the Murchison and Allende meteorites. By exploiting the unique ability of these molecules to trap noble gases, we have determined that fullerene is indeed a new carrier phase for noble gases in meteorites.

  1. Storage of nuclear materials by encapsulation in fullerenes

    DOEpatents

    Coppa, Nicholas V.

    1994-01-01

    A method of encapsulating radioactive materials inside fullerenes for stable long-term storage. Fullerenes provide a safe and efficient means of disposing of nuclear waste which is extremely stable with respect to the environment. After encapsulation, a radioactive ion is essentially chemically isolated from its external environment.

  2. Transport of Fullerene Nanoparticles in Saturated Porous Media

    EPA Science Inventory

    The high strength, electrical conductivity, and electron affinity of fullerenes has lead to their utilization in fuel cells and drug-delivery devices, as well as in cosmetics and other applications. Though C60 fullerene is very insoluble in water, studies have shown that C60 ful...

  3. Fullerene derivatives as electron donor for organic photovoltaic cells

    SciTech Connect

    Zhuang, Taojun; Wang, Xiao-Feng E-mail: ziruo@yz.yamagata-u.ac.jp; Sano, Takeshi; Kido, Junji; Hong, Ziruo E-mail: ziruo@yz.yamagata-u.ac.jp; Department of Materials Science and Engineering, University of California, Los Angeles, California 90095 ; Yang, Yang

    2013-11-11

    We demonstrated the performance of unconventional, all-fullerene-based, planar heterojunction (PHJ) organic photovoltaic (OPV) cells using fullerene derivatives indene-C{sub 60} bisadduct (ICBA) and phenyl C{sub 61}-butyric acid methyl ester as the electron donors with fullerene C{sub 70} as the electron acceptor. Two different charge generation processes, including charge generation in the fullerene bulk and exciton dissociation at the donor-acceptor interface, have been found to exist in such all-fullerene-based PHJ cells and the contribution to the total photocurrent from each process is strongly dependent on the thickness of fullerene donor. The optimized 5?nm ICBA/40?nm C{sub 70} PHJ cell gives clear external quantum efficiency responses for the long-wavelength photons corresponding to the dissociation of strongly bound Frenkel excitons, which is hardly observed in fullerene-based single layer reference devices. This approach using fullerene as a donor material provides further possibilities for developing high performance OPV cells.

  4. Nanoencapsulation of Fullerenes in Organic Structures with Nonpolar Cavities

    NASA Astrophysics Data System (ADS)

    Murthy, C. N.

    2005-01-01

    The formation of supramolecular structures, assemblies, and arrays held together by weak intermolecular interactions and non-covalent binding mimicking natural processes has been used in applications being anticipated in nanotechnology, biotechnology and the emerging field of nanomedicine. Encapsulation of C60 fullerene by cyclic molecules like cyclodextrins and calixarenes has potential for a number of applications. Similarly, biomolecules like lysozyme also have been shown to encapsulate C60 fullerene. This poster article reports the recent trends and the results obtained in the nanoencapsulation of fullerenes by biomolecules containing nonpolar cavities. Lysozyme was chosen as the model biomolecule and it was observed that there is no covalent bond formed between the bimolecule and the C60 fullerene. This was confirmed from fluorescence energy transfer studies. UV Vis studies further supported this observation that it is possible to selectively remove the C60 fullerene from the nonpolar cavity. This behavior has potential in biomedical applications

  5. Stability of carbonaceous dust analogues and glycine under UV irradiation and electron bombardment.

    PubMed

    Mat, Beln; Tanarro, Isabel; Moreno, Miguel A; Jimnez-Redondo, Miguel; Escribano, Rafael; Herrero, Vctor J

    2014-01-01

    The effect of UV photon (120-200 nm) and electron (2 keV) irradiation of analogues of interstellar carbonaceous dust and of glycine were investigated by means of IR spectroscopy. Films of hydrogenated amorphous carbon (HAC), taken as dust analogues, were found to be stable under UV photon and electron bombardment. High fluences of photons and electrons, of the order of 10(19) cm(-2), were needed for a film depletion of a few percent. UV photons were energetically more effective than electrons for depletion and led to a certain dehydrogenation of the HAC samples, whereas electrons led seemingly to a gradual erosion with no appreciable changes in the hydrocarbon structure. The rates of change observed may be relevant over the lifetime of a diffuse cloud, but cannot account for the rapid changes in hydrocarbon IR bands during the evolution of some proto-planetary nebulae. Glycine samples under the same photon and electron fluxes decay at a much faster rate, but tend usually to an equilibrium value different from zero, especially at low temperatures. Reversible reactions re-forming glycine, or the build-up of less transparent products, could explain this behavior. CO2 and methylamine were identified as UV photoproducts. Electron irradiation led to a gradual disappearance of the glycine layers, also with formation of CO2. No other reaction products were clearly identified. The thicker glycine layers (a few hundred nm) were not wholly depleted, but a film of the order of the electron penetration depth (80 nm), was totally destroyed with an electron fluence of -1 x 10(18) cm(-2). A 60 nm ice layer on top of glycine provided only partial shielding from the 2 keV electrons. From an energetic point of view, 2 keV electrons are less efficient than UV photons and, according to literature data, much less efficient than MeV protons for the destruction of glycine. The use of keV electrons to simulate effects of cosmic rays on analogues of interstellar grains should be taken with care, due to the low penetration depths of electrons in many samples of interest. PMID:25302385

  6. Advances in fast-atom-bombardment mass spectroscopy

    SciTech Connect

    Hemling, M.E.

    1986-01-01

    A comparison of fast atom bombardment and field desorption mass spectrometry was made to determine relative sensitivity and applicability. A series of glycosphingolipids and a series of protected oligonucleotides of known structure were analyzed to ascertain the potential utility of fast atom bombardment mass spectrometry in the structural elucidation of novel compounds in these classes. Negative ion mass markers were also developed. Fast atom bombardment was found to be one-to-two orders of magnitude more sensitive than field desorption based on the analysis of a limited number of compounds from several classes. Superior sensitivity was not universal and field desorption was clearly better in certain cases. In the negative ion mode in particular, fast atom bombardment was found to be a useful tool for the determination of the primary structure of glycosphingolipids and oligonucleotides. Carbohydrate sequence and branching information, and a fatty acid and lipid base composition were readily obtained from the mass spectra of glycosphingolipids while bidirectional nucleotide sequence, nucleotide base, and protecting group assignments were obtained for oligonucleotides. Based on this knowledge, a tentative structure of a human peripheral nervous system glycosphingolipid implicated in certain cases of disorders such as amyotrophic lateral sclerosis, Lou Gehrig's Disease, was proposed. Suitable negative ion mass markers were found in dispersions of poly(ethylene) and poly(propylene)glycols in a triethylenetetramine matrix, a matrix which also proved useful in the analysis of glycosphingolipids. These polyglycol dispersions provided ions for calibration to 2300 daltons.

  7. Dating Howardite Melt Clasts: Evidence for an Extended Vestan Bombardment?

    NASA Technical Reports Server (NTRS)

    Cartwright, J. A.; Hodges, K. V.; Wadhwa, M.; Mittlefehldt, D. W.

    2016-01-01

    Howardites are polymict breccias that, together with eucrites and diogenites (HED), likely originate from the vestan surface (regolith/ megaregolith), and display a heterogeneous distribution of eucritic and diogenitic material. Melt clasts are also present alongside other regolithic features within howardites, and are noteworthy for their compositional variability and appearance. Melt clasts formed by impact events provide a snapshot of the timings and conditions of surface gardening and bombardment on the vestan surface. By dating such clasts, we aim to better constrain the timings of impact events on Vesta, and to establish whether the impact flux in the asteroid belt was similar to that on the Moon. As the Moon is used as the basis for characterising impact models of the inner solar system, it is necessary to verify that apparent wide-scale events are seen in other planetary bodies. In particular, the observed clustering of Apollo melt clast ages between 3.8-4.0 Ga has led to two hypotheses: 1) The Moon was subjected to a sudden event - 'Lunar Cataclysm' or period of 'Late Heavy Bombardment' (LHB), 2) The age cluster represents the end of an epoch of declining bombardment or 'Heavy Bombardment. No consensus has emerged regarding one or other hypothesis. We are testing these hypotheses by seeking evidence for such events in materials other than those derived from the Moon.

  8. JOVIAN EARLY BOMBARDMENT: PLANETESIMAL EROSION IN THE INNER ASTEROID BELT

    SciTech Connect

    Turrini, D.; Coradini, A.; Magni, G.

    2012-05-01

    The asteroid belt is an open window on the history of the solar system, as it preserves records of both its formation process and its secular evolution. The progenitors of the present-day asteroids formed in the Solar Nebula almost contemporary to the giant planets. The actual process producing the first generation of asteroids is uncertain, strongly depending on the physical characteristics of the Solar Nebula, and the different scenarios produce very diverse initial size-frequency distributions (SFDs). In this work, we investigate the implications of the formation of Jupiter, plausibly the first giant planet to form, on the evolution of the primordial asteroid belt. The formation of Jupiter triggered a short but intense period of primordial bombardment, previously unaccounted for, which caused an early phase of enhanced collisional evolution in the asteroid belt. Our results indicate that this Jovian Early Bombardment caused the erosion or the disruption of bodies smaller than a threshold size, which strongly depends on the SFD of the primordial planetesimals. If the asteroid belt was dominated by planetesimals less than 100 km in diameter, the primordial bombardment would have caused the erosion of bodies smaller than 200 km in diameter. If the asteroid belt was instead dominated by larger planetesimals, the bombardment would have resulted in the destruction of bodies as big as 500 km.

  9. Fullerene fine particles adhere to pollen grains and affect their autofluorescence and germination

    PubMed Central

    Aoyagi, Hideki; Ugwu, Charles U

    2011-01-01

    Adhesion of commercially produced fullerene fine particles to Cryptomeria japonica, Chamaecyparis obtusa and Camellia japonica pollen grains was investigated. The autofluorescence of pollen grains was affected by the adhesion of fullerene fine particles to the pollen grains. The degree of adhesion of fullerene fine particles to the pollen grains varied depending on the type of fullerene. Furthermore, germination of Camellia japonica pollen grains was inhibited by the adhesion of fullerene fine particles. PMID:24198486

  10. A fullerene molecular tip can detect localized and rectified electron tunneling within a single fullereneporphyrin pair

    PubMed Central

    Nishino, Tomoaki; Ito, Takashi; Umezawa, Yoshio

    2005-01-01

    A fullerene molecular tip was used to detect electron tunneling from a single porphyrin molecule. Electron tunneling was found to occur locally from an electron-donating moiety of the porphyrin to the fullerene through charge-transfer interaction between them. In addition, electron tunneling within the single fullereneporphyrin pair exhibited rectifying behavior in which electrons can be driven only at the direction from the porphyrin to the fullerene. It is demonstrated that localized electron tunneling enables us to spatially visualize the frontier orbital of the porphyrin involved in electron tunneling. In addition, rectification demonstrates that the fullereneporphyrin pair constitutes a molecular rectifier. We believe that molecular tips bring insight into intermolecular electron transmission toward realization of molecular electronics as shown here. PMID:15809427

  11. Respiratory chain inhibition by fullerene derivatives: hydrogen peroxide production caused by fullerene derivatives and a respiratory chain system.

    PubMed

    Mashino, Tadahiko; Usui, Noriko; Okuda, Kensuke; Hirota, Takashi; Mochizuki, Masataka

    2003-04-01

    Fullerene is a new type of carbon allotrope. We have shown that the fullerene derivative C(60)-bis(N,N-dimethylpyrrolidinium iodide), a regio isomer mixture, inhibited Escherichia coli growth and dioxygen uptake caused by E. coli and glucose. This result indicates that the mechanism of the bacteriostatic effect is the inhibition of energy metabolism. In this study, we isolated two regio isomers of C(60)-bis(N,N-dimethylpyrrolidinium iodide) and studied their effect on E. coli growth and on respiratory chain activity. In dioxygen uptake caused by the inner-membrane and NADH, the effect of fullerene derivatives was biphasic. At low concentrations of both fullerene derivatives, dioxygen uptake was inhibited, whereas at high concentrations, it was increased. At high concentrations, consumed dioxygen was converted to H(2)O(2). An electrochemical study revealed that reduced fullerene derivatives react with dioxygen. This activity was closely related to a redox property of the isomers. PMID:12628669

  12. The effect of fullerenes and functionalized fullerenes on Daphnia magna phototaxis and swimming behavior.

    PubMed

    Brausch, Kathryn A; Anderson, Todd A; Smith, Philip N; Maul, Jonathan D

    2011-04-01

    The effects of carbon fullerenes (C(60) ) on the environment is a growing concern as the use of nanotechnology continues to increase. Previous studies have reported alteration in Daphnia magna behavior, including increased hopping frequency, heart rate, and appendage movement in response to tetrahydrofuran-solubilized C(60) and increased hopping rate and appendage movement in response to tetrahydrofuran-solubilized C(60) HxC(70) Hx exposure. The objective of the current study was to evaluate effects of water-stirred C(60) and sonicated carboxylic acid functionalized fullerenes (fC(60) ) on D. magna behavior. Behavioral endpoints are important because changes in behavior can influence predator avoidance behaviors, alter predation risk, and potentially lead to population-level effects in D. magna. To evaluate the potential effect of fullerenes on phototactic behavior, D. magna were exposed to 545.4?g/L C(60) and 545.6?g/L fC(60) , and vertical position was monitored. Daphnia magna were also exposed to 545.4?g/L C(60) , 545.6?g/L fC(60) , and 829.3?g/L fC(60) , and swimming movements were recorded. Fullerenes altered the vertical migration response of D. magna to the addition of food, but D. magna vertical position response to predator cues was similar for fullerenes and controls. In addition, D. magna reduced swimming speed when exposed to C(60) , but other components of D. magna swimming behavior were not affected. This research supports previous findings and suggests that C(60) may influence D. magna behavior and highlights the need for further research on sublethal behavioral modifications in aquatic organisms in response to nanomaterials. PMID:21184527

  13. Fe embedded in ice: The impacts of sublimation and energetic particle bombardment

    NASA Astrophysics Data System (ADS)

    Frankland, Victoria L.; Plane, John M. C.

    2015-05-01

    Icy particles containing a variety of Fe compounds are present in the upper atmospheres of planets such as the Earth and Saturn. In order to explore the role of ice sublimation and energetic ion bombardment in releasing Fe species into the gas phase, Fe-dosed ice films were prepared under UHV conditions in the laboratory. Temperature-programmed desorption studies of Fe/H2O films revealed that no Fe atoms or Fe-containing species co-desorbed along with the H2O molecules. This implies that when noctilucent ice cloud particles sublimate in the terrestrial mesosphere, the metallic species embedded in them will coalesce to form residual particles. Sputtering of the Fe-ice films by energetic Ar+ ions was shown to be an efficient mechanism for releasing Fe into the gas phase, with a yield of 0.08 (Ar+ energy=600 eV). Extrapolating with a semi-empirical sputtering model to the conditions of a proton aurora indicates that sputtering by energetic protons (>100 keV) should also be efficient. However, the proton flux in even an intense aurora will be too low for the resulting injection of Fe species into the gas phase to compete with that from meteoric ablation. In contrast, sputtering of the icy particles in the main rings of Saturn by energetic O+ ions may be the source of recently observed Fe+ in the Saturnian magnetosphere. Electron sputtering (9.5 keV) produced no detectable Fe atoms or Fe-containing species. Finally, it was observed that Fe(OH)2 was produced when Fe was dosed onto an ice film at 140 K (but not at 95 K). Electronic structure theory shows that the reaction which forms this hydroxide from adsorbed Fe has a large barrier of about 0.7 eV, from which we conclude that the reaction requires both translationally hot Fe atoms and mobile H2O molecules on the ice surface.

  14. Current through fullerenes with calcium atom encapsulated

    NASA Astrophysics Data System (ADS)

    Vanaie, Hamidreza; Yaghobi, Mojtaba; Asvar, Adel; Heidari, Ebrahim; Sedaghat, Zahra

    2015-09-01

    A theoretical study of quantum transport through Ca@C60 or Ca2+@C60 molecules is considered by using the non-equilibrium Greens function (NEGF) formalism. The effects of gate and bias voltages, encapsulation, position and displacement of ion into the cage are important factors in endohedral molecular junction that are considered in the calculations of our study. The current value against the bias voltage, independent of the contacts strength, decreases when the calcium atom lies far from the cage center. Also, negative differential resistance (NDR) behavior is observed when it is in center of fullerene.

  15. Organic hard masks utilizing fullerene derivatives

    NASA Astrophysics Data System (ADS)

    Frommhold, Andreas; Brown, Alan G.; Palmer, Richard E.; Lada, Tom; Robinson, Alex P.

    2015-03-01

    We have developed a series of fullerene containing materials for use as organic hard masks. Films with a thickness of up to 250 nm were deposited via spin coating. After a crosslinking bake the films exhibit good thermal stability - in the best case a mass loss of less than 3% at 400 C is seen. Etch resistance of the different formulations are presented and hig-hresolution patterning is demonstrated. During the transfer into silicon no adverse "wiggling" is observed at high resolution. We attribute this to the low levels of aliphatic hydrogen present in the materials.

  16. Infrared spectroscopy of fullerene C60/anthracene adducts

    NASA Astrophysics Data System (ADS)

    García-Hernández, D. A.; Cataldo, F.; Manchado, A.

    2013-09-01

    Recent Spitzer Space Telescope observations of several astrophysical environments such as planetary nebulae, reflection nebulae and R Coronae Borealis stars show the simultaneous presence of mid-infrared features attributed to neutral fullerene molecules (i.e. C60) and polycyclic aromatic hydrocarbons (PAHs). If C60 fullerenes and PAHs coexist in fullerene-rich space environments, then C60 may easily form adducts with a number of different PAH molecules, at least with catacondensed PAHs. Here we present the laboratory infrared spectra (˜2-25 μm) of C60 fullerene and anthracene Diels-Alder mono- and bis-adducts as produced by sonochemical synthesis. We find that C60/anthracene Diels-Alder adducts display spectral features strikingly similar to those from C60 (and C70) fullerenes and other unidentified infrared emission features. Thus, fullerene adducts - if formed under astrophysical conditions and are stable/abundant enough - may contribute to the infrared emission features observed in fullerene-containing circumstellar/interstellar environments.

  17. Anti-Influenza Activity of C60 Fullerene Derivatives

    PubMed Central

    Shoji, Masaki; Takahashi, Etsuhisa; Hatakeyama, Dai; Iwai, Yuma; Morita, Yuka; Shirayama, Riku; Echigo, Noriko; Kido, Hiroshi; Nakamura, Shigeo; Mashino, Tadahiko; Okutani, Takeshi; Kuzuhara, Takashi

    2013-01-01

    The H1N1 influenza A virus, which originated in swine, caused a global pandemic in 2009, and the highly pathogenic H5N1 avian influenza virus has also caused epidemics in Southeast Asia in recent years. Thus, the threat from influenza A remains a serious global health issue, and novel drugs that target these viruses are highly desirable. Influenza A RNA polymerase consists of the PA, PB1, and PB2 subunits, and the N-terminal domain of the PA subunit demonstrates endonuclease activity. Fullerene (C60) is a unique carbon molecule that forms a sphere. To identify potential new anti-influenza compounds, we screened 12 fullerene derivatives using an in vitro PA endonuclease inhibition assay. We identified 8 fullerene derivatives that inhibited the endonuclease activity of the PA N-terminal domain or full-length PA protein in vitro. We also performed in silico docking simulation analysis of the C60 fullerene and PA endonuclease, which suggested that fullerenes can bind to the active pocket of PA endonuclease. In a cell culture system, we found that several fullerene derivatives inhibit influenza A viral infection and the expression of influenza A nucleoprotein and nonstructural protein 1. These results indicate that fullerene derivatives are possible candidates for the development of novel anti-influenza drugs. PMID:23785493

  18. Process for the removal of impurities from combustion fullerenes

    DOEpatents

    Alford, J. Michael; Bolskar, Robert

    2005-08-02

    The invention generally relates to purification of carbon nanomaterials, particularly fullerenes, by removal of PAHs and other hydrocarbon impurities. The inventive process involves extracting a sample containing carbon nanomaterials with a solvent in which the PAHs are substantially soluble but in which the carbon nanomaterials are not substantially soluble. The sample can be repeatedly or continuously extracted with one or more solvents to remove a greater amount of impurities. Preferred solvents include ethanol, diethyl ether, and acetone. The invention also provides a process for efficiently separating solvent extractable fullerenes from samples containing fullerenes and PAHs wherein the sample is extracted with a solvent in which both fullerenes and PAHs are substantially soluble and the sample extract then undergoes selective extraction to remove PAHs. Suitable solvents in which both fullerenes and PAHs are soluble include o-xylene, toluene, and o-dichlorobenzene. The purification process is capable of treating quantities of combustion soot in excess of one kilogram and can produce fullerenes or fullerenic soot of suitable purity for many applications.

  19. Anti-influenza activity of c60 fullerene derivatives.

    PubMed

    Shoji, Masaki; Takahashi, Etsuhisa; Hatakeyama, Dai; Iwai, Yuma; Morita, Yuka; Shirayama, Riku; Echigo, Noriko; Kido, Hiroshi; Nakamura, Shigeo; Mashino, Tadahiko; Okutani, Takeshi; Kuzuhara, Takashi

    2013-01-01

    The H1N1 influenza A virus, which originated in swine, caused a global pandemic in 2009, and the highly pathogenic H5N1 avian influenza virus has also caused epidemics in Southeast Asia in recent years. Thus, the threat from influenza A remains a serious global health issue, and novel drugs that target these viruses are highly desirable. Influenza A RNA polymerase consists of the PA, PB1, and PB2 subunits, and the N-terminal domain of the PA subunit demonstrates endonuclease activity. Fullerene (C60) is a unique carbon molecule that forms a sphere. To identify potential new anti-influenza compounds, we screened 12 fullerene derivatives using an in vitro PA endonuclease inhibition assay. We identified 8 fullerene derivatives that inhibited the endonuclease activity of the PA N-terminal domain or full-length PA protein in vitro. We also performed in silico docking simulation analysis of the C60 fullerene and PA endonuclease, which suggested that fullerenes can bind to the active pocket of PA endonuclease. In a cell culture system, we found that several fullerene derivatives inhibit influenza A viral infection and the expression of influenza A nucleoprotein and nonstructural protein 1. These results indicate that fullerene derivatives are possible candidates for the development of novel anti-influenza drugs. PMID:23785493

  20. On the Excitation and Formation of Circumstellar Fullerenes

    NASA Astrophysics Data System (ADS)

    Bernard-Salas, Jeronimo; Cami, J.; Peeters, E.; Jones, A. P.; Micelotta, E.; Groenewegen, M. A.

    2013-01-01

    Recently, we reported the first detection of fullerenes (C60, C70) in space, specifically in Tc1, a young planetary nebulae (PNe). Once injected into the ISM, these stable species survive and are thus probably widespread in the Galaxy where they contribute to interstellar extinction, heating processes, and complex chemical reactions. Following our discovery, fullerenes have now been detected in a wide range of sources (post-AGBs, PNe, reflection nebula, HII regions, H-poor stars, and YSOs), showing that when conditions are favorable, fullerenes are formed in large quantities. The challenge resides now in determining its excitation mechanisms (fluorescence vs. thermal), as this sets their diagnostic value. To this end we have analyzed the mid-IR spectrum of three fullerene-rich PNe Tc1, SMP SMC 16, and SMP LMC 56 and compared them with thermal and fluorescence models. The strength of the fullerene bands in the three planetary nebulae is very similar, while the strength of the radiation field, is markedly different. Additionally, the spatial profile of different dust components in Tc1 indicates that the fullerene emission (C60) peaks far away from the central source. All this is hard to reconcile with a thermal origin for the fullerene excitation, and thus favors fluorescence as the excitation mechanism. In addition, the spectra in the three PNe show a strong broad plateau with substructure in the 6-9um range, and which is likely related to the fullerene formation mechanism. We present model spectra for 3 nm radius HAC particles and show that these can reproduce the 6-9um plateau, which may imply that fullerenes are formed by photo-chemical processing of hydrogenated amorphous carbon (HAC) nano-particles.

  1. Intravenous coronary angiography utilizing K-emission and bremsstrahlung X-rays produced by electron bombardment

    SciTech Connect

    1992-12-31

    The screening of the general population for coronary artery disease would be practical if a method existed for visualizing the extent of occlusion after an intravenous injection of contrast agent. Measurements performed with synchrotron radiation at SSRL and NSLS have shown that such an intravenous angiography procedure would be possible with an intense source of monochromatic X-rays. Because of the high cost of an electron synchrotron, theoretical analysis and experiments using inanimate phantoms has been undertaken to demonstrate the feasibility of using the spectrum produced by two appropriately chosen anode materials when bombarded with electrons in the 100--500 keV energy range for angiography. By using the X-rays emitted at 120{degree} to the incident electron direction, about 20--30% of the X-ray intensity would be due to K-emission lines. Calculations using the TIGERP Monte Carlo Code, have shown that high quality angiograms of human coronary arteries should be possible with a contrast agent containing ytterbium, if an electron beam pulses of 16 kJ were used for each anode target. The experimental program supported in part by the DOE has consisted of these theoretical calculations and experiments at the Dynamitron Electron Accelerator Facility at BNL.

  2. The effect of electron bombardment on optical properties of n-type silicon

    NASA Astrophysics Data System (ADS)

    Sari, Amir H.; Osman, F.; Ghoranneviss, M.; Hora, H.; Hpfl, R.; Hantehzadeh, M. R.

    2004-10-01

    The production of p-n junctions and polar transistors in silicon to small scale lengths may be possible by plasma and electron beam techniques using the sub-threshold change of n-silicon into p-silicon by electron beam and its reversion at higher electron beam intensities. As a first step, in this study, experimental observation of the effect of electron beam on optical properties of n-type silicon samples is described. Electron bombardment with the energy of 20 keV and different doses in the range of 10 16 to 10 19 electron/cm 2 has been carried out. Use was made of a new design of an electron beam gun as described in details, using a helium obstructed discharge of a concave cold cathode. Optical properties of irradiated samples were determined by a UV-vis-NIR spectrophotometer. The results show an increase in the longer wave length than the fundamental band gap absorption with increasing electron dose.

  3. On the validity of the electron transfer model in photon emission from ion bombarded vanadium surfaces

    NASA Astrophysics Data System (ADS)

    El Fqih, M. Ait; El Boujladi, A.; Jourdani, R.; Kaddouri, A.

    2011-06-01

    The spectral structure of the radiation (250-500 nm) emitted during sputtering of clean and oxygen-covered polycrystalline vanadium and V2O5 by 5 keV Kr+ ions is presented. The optical spectra obtained by bombarding the vanadium target consist of series of sharp lines, which are attributed to neutral and ionic excited V. The same lines are observed in the spectra of V2O5 and vanadium when oxygen is present. The absolute intensities of VI and VII lines are measured under similar conditions for all spectra. The difference in photon yield from the clean and oxide vanadium targets is discussed in terms of the electron-transfer processes between the excited sputtered and electronic levels of the two types of surfaces. We have examined the existing models of ionisation, excitation, neutralisation and de-excitation of atomic particles in the vicinity of solid surfaces. Continuum radiation was also observed and interpreted as a result of the emission of excited molecules of the metal-oxide.

  4. Continuum simulations of water flow past fullerene molecules

    NASA Astrophysics Data System (ADS)

    Popadi?, A.; Praprotnik, M.; Koumoutsakos, P.; Walther, J. H.

    2015-09-01

    We present continuum simulations of water flow past fullerene molecules. The governing Navier-Stokes equations are complemented with the Navier slip boundary condition with a slip length that is extracted from related molecular dynamics simulations. We find that several quantities of interest as computed by the present model are in good agreement with results from atomistic and atomistic-continuum simulations at a fraction of the cost. We simulate the flow past a single fullerene and an array of fullerenes and demonstrate that such nanoscale flows can be computed efficiently by continuum flow solvers, allowing for investigations into spatiotemporal scales inaccessible to atomistic simulations.

  5. Silver(i)-mediated three-component annulation reaction of [60]fullerene, sulfonylhydrazones, and nitriles: leading to diverse disubstituted [60]fullerene-fused dihydropyrroles.

    PubMed

    Chao, Di; Liu, Tong-Xin; Ma, Nana; Zhang, Pengling; Fu, Zheng; Ma, Jinliang; Liu, Qingfeng; Zhang, Fengjin; Zhang, Zhiguo; Zhang, Guisheng

    2016-01-01

    A novel Ag(i)-induced three-component annulation reaction of [60]fullerene with sulfonylhydrazones and nitriles has been developed for the efficient synthesis of diverse disubstituted [60]fullerene-fused dihydropyrroles. The reaction exhibits a broad substrate scope and excellent functional-group tolerance, and also allows for the synthesis of fullerene-bound macromolecules. PMID:26594033

  6. Water clusters confined in icosahedral fullerene cavities

    NASA Astrophysics Data System (ADS)

    Hernndez-Rojas, J.; Monteseguro, V.; Bretn, J.; Gomez Llorente, J. M.

    2012-05-01

    Likely candidates for the global energy minima of endohedral (H2O)N@C60 and (H2O)N@C180, and exohedral (H2O)NC180 water-fullerene clusters with N ? 20, are found using basin-hopping global optimization. The potential energy surfaces are constructed using both the rigid TIP4P and the flexible q-TIP4P/F potentials to model the water-water interaction, together with a Lennard-Jones potential for the water-fullerene interaction. In agreement with previous ab initio studies, we find that the small C60 cavity is able to encapsulate exothermically only one water molecule. On the other hand, the larger C180 cavity can encapsulate up to 17 water molecules exothermically. This threshold value is higher than that reported in a previous ab initio study (N ? 12). New confined water cluster structures are found. One which is particularly interesting is the structure of (H2O)14@C180, with the water molecules forming an internal cage in which six oxygen atoms are located at the vertices of an almost regular octahedron and the eight remaining ones lie on top of the octahedron faces. For N ? 15 one water molecule is always present at the center of the water cage, which is distorted to accommodate the extra molecules.

  7. Interaction of C(60) fullerene with lipids.

    PubMed

    Cataldo, Franco

    2010-06-01

    Unsaturated lipids when exposed to air at room temperature undergo a slow autoxidation. When fullerene C(60) was dissolved in selected lipids (ethyl oleate, ethyl linoleate, linseed oil and castor oil) the spectrophotometric analysis shows that the oxidation is concentrated to C(60) which is converted to an epoxide C(60)O. Thus, fullerene C(60) displays antioxidant activity not only when dissolved in unsaturated lipids but also, more generally, when dissolved in unsaturated solvents subjected to autoxidation like, for example, in cyclohexene. The behaviour of C(60) in ethyl oleate has been compared with that of the known antioxidant TMPPD (N,N',N,N,'-tetramethyl-p-phenylenediamine) in ethyl oleate. The mechanism of the antioxidant action of C(60) in lipids has been proposed. The kinetics of C(60) oxidation in lipids was determined spectrophotometrically both at room temperature in the dark and under UV irradiation. The oxidized products derived from C(60) photo-oxidation in lipids have been identified. PMID:20338159

  8. O+ bombardment of an O and O2 Thermosphere

    NASA Astrophysics Data System (ADS)

    McKeown, M.; Johnson, R. E.

    2000-10-01

    Ejection of atoms and molecules from the atmosphere of Mars is caused by energetic O+ pickup-ion bombardment [Luhmann et al, 1992; Jakosky et al.,1994], a process referred to as atmospheric sputtering. This process also occurs on other bodies which have molecules at the exobase such as Europa and Titan. Using a Monte Carlo procedure we calculate the rate of ejection of particles from a model thermosphere composed of O and O2 which is bombarded by energetic O+. To allow for dissociation of O2, collisions between high energy O atoms and O2 molecules are treated using classical molecular dynamics with semi-empirical interaction potentials. O + O collisions are treated with the magic formula method of Zeigler et al.,1985. The effect of molecular binding on the atmospheric sputtering yield is examined.

  9. Molecular dynamics study of self-agglomeration of charged fullerenes in solvents.

    PubMed

    Banerjee, Soumik

    2013-01-28

    The agglomeration of fullerenes in solvents is an important phenomenon that is relevant to controlled synthesis of fullerene-based nanowires as well as fullerene-based composites. The molecular aggregation in solvents depends on the atomistic interactions of fullerene with the solvent and is made complicated by the fact that fullerenes accrue negative surface charges when present in solvents such as water. In the present work, we simulated fullerenes of varying size and shape (C60, C180, C240, and C540) with and without surface charges in polar protic (water), polar aprotic (acetone), and nonpolar (toluene) solvents using molecular dynamics method. Our results demonstrate that uncharged fullerenes form agglomerates in polar solvents such as water and acetone and remain relatively dispersed in nonpolar toluene. The presence of surface charge significantly reduces agglomerate size in water and acetone. Additionally, the relative influence of surface charge on fullerene agglomeration depends on the size and geometry of the fullerene with larger fullerenes forming relatively smaller agglomerates. We evaluated the diffusion coefficients of solvent molecules within the solvation shell of fullerenes and observed that they are much lower than the bulk solvent and are strongly associated with the fullerenes as seen in the corresponding radial distribution functions. To correlate agglomerate size with the binding energy between fullerenes, we evaluated the potential of mean force between fullerenes in each solvent. Consistent with the solubility of fullerenes, binding energy between fullerenes is the greatest in water followed by acetone and toluene. The presence of charge decreases the binding energy of fullerenes in water and thus results in dispersed fullerenes. PMID:23387595

  10. Molecular dynamics study of self-agglomeration of charged fullerenes in solvents

    NASA Astrophysics Data System (ADS)

    Banerjee, Soumik

    2013-01-01

    The agglomeration of fullerenes in solvents is an important phenomenon that is relevant to controlled synthesis of fullerene-based nanowires as well as fullerene-based composites. The molecular aggregation in solvents depends on the atomistic interactions of fullerene with the solvent and is made complicated by the fact that fullerenes accrue negative surface charges when present in solvents such as water. In the present work, we simulated fullerenes of varying size and shape (C60, C180, C240, and C540) with and without surface charges in polar protic (water), polar aprotic (acetone), and nonpolar (toluene) solvents using molecular dynamics method. Our results demonstrate that uncharged fullerenes form agglomerates in polar solvents such as water and acetone and remain relatively dispersed in nonpolar toluene. The presence of surface charge significantly reduces agglomerate size in water and acetone. Additionally, the relative influence of surface charge on fullerene agglomeration depends on the size and geometry of the fullerene with larger fullerenes forming relatively smaller agglomerates. We evaluated the diffusion coefficients of solvent molecules within the solvation shell of fullerenes and observed that they are much lower than the bulk solvent and are strongly associated with the fullerenes as seen in the corresponding radial distribution functions. To correlate agglomerate size with the binding energy between fullerenes, we evaluated the potential of mean force between fullerenes in each solvent. Consistent with the solubility of fullerenes, binding energy between fullerenes is the greatest in water followed by acetone and toluene. The presence of charge decreases the binding energy of fullerenes in water and thus results in dispersed fullerenes.

  11. Enhancing fullerene-based solar cell lifetimes by addition of a fullerene dumbbell.

    PubMed

    Schroeder, Bob C; Li, Zhe; Brady, Michael A; Faria, Gregrio Couto; Ashraf, Raja Shahid; Takacs, Christopher J; Cowart, John S; Duong, Duc T; Chiu, Kar Ho; Tan, Ching-Hong; Cabral, Joo T; Salleo, Alberto; Chabinyc, Michael L; Durrant, James R; McCulloch, Iain

    2014-11-17

    Cost-effective, solution-processable organic photovoltaics (OPV) present an interesting alternative to inorganic silicon-based solar cells. However, one of the major remaining challenges of OPV devices is their lack of long-term operational stability, especially at elevated temperatures. The synthesis of a fullerene dumbbell and its use as an additive in the active layer of a PCDTBT:PCBM-based OPV device is reported. The addition of only 20?% of this novel fullerene not only leads to improved device efficiencies, but more importantly also to a dramatic increase in morphological stability under simulated operating conditions. Dynamic secondary ion mass spectrometry (DSIMS) and TEM are used, amongst other techniques, to elucidate the origins of the improved morphological stability. PMID:25264304

  12. Enhancing Fullerene-Based Solar Cell Lifetimes by Addition of a Fullerene Dumbbell**

    PubMed Central

    Schroeder, Bob C; Li, Zhe; Brady, Michael A; Faria, Gregrio Couto; Ashraf, Raja Shahid; Takacs, Christopher J; Cowart, John S; Duong, Duc T; Chiu, Kar Ho; Tan, Ching-Hong; Cabral, Joo T; Salleo, Alberto; Chabinyc, Michael L; Durrant, James R; McCulloch, Iain

    2014-01-01

    Cost-effective, solution-processable organic photovoltaics (OPV) present an interesting alternative to inorganic silicon-based solar cells. However, one of the major remaining challenges of OPV devices is their lack of long-term operational stability, especially at elevated temperatures. The synthesis of a fullerene dumbbell and its use as an additive in the active layer of a PCDTBT:PCBM-based OPV device is reported. The addition of only 20?% of this novel fullerene not only leads to improved device efficiencies, but more importantly also to a dramatic increase in morphological stability under simulated operating conditions. Dynamic secondary ion mass spectrometry (DSIMS) and TEM are used, amongst other techniques, to elucidate the origins of the improved morphological stability. PMID:25264304

  13. Evolution of SiC Nanocluster from Carbon Fullerene: A Density Functional Theoretic Study

    SciTech Connect

    Huda, M. N.; Ray, A. K.

    2008-01-01

    Stability of SiC fullerene type structures is still an unsolved issue as no experimental confirmation has been reported so far regarding its existence. However, theoretical reports are available in the literature where carbon fullerenes were taken as base models for SiC fullerene structures. In this present Letter we show by a systematic study on the C{sub 20} fullerene that this approach may not always produce the ground state structure in fullerene form. Instead, the energetically favorable structure could be highly distorted and open structure. However, we observed a very systematic linear trend in the evolution of binding energies of SiC clusters from the carbon fullerene.

  14. Hydrogen storage in fullerenes and in an organic hydride

    SciTech Connect

    Wang, J.C.; Murphy, R.W.; Chen, F.C.; Loutfy, R.O.; Veksler, E.; Li, W.

    1998-05-29

    While the authors have demonstrated the importance and usefulness of thermal management to the hydrogen storage in fullerenes, their recent effort has concentrated on materials improvement and physical model development. In this paper, they report the results of this effort as follows: (1) Liquid phase hydrogenation of fullerenes indicated that more than 6 wt% capacity can be obtained at 180 C, 350--400 psi; (2) Dehydrogenation of fullerenes hydrides below 225 C was demonstrated using an Ir-based P-C-P pincer complex catalyst; (3) Cyclic hydrogenation and dehydrogenation tests of an organic hydride at 7 wt% capacity were conducted at 180--260 C; and (4) Physical models developed for fullerenes were determined to be applicable to this organic hydride (with much smaller activation energies).

  15. Production and Consumption of Reactive Oxygen Species by Fullerenes

    EPA Science Inventory

    Reactive oxygen species (ROS) are one of the most important intermediates in chemical, photochemical, and biological processes. To understand the environmental exposure and toxicity of fullerenes better, the production and consumption of ROS (singlet oxygen, superoxide, hydrogen ...

  16. Dynamics of H2O Molecules Confined in Fullerenes

    NASA Astrophysics Data System (ADS)

    Tutchton, Roxanne; Larson, Paul; Wu, Zhigang

    2014-03-01

    Structural and dynamical properties of confined water in nanostructures are expected to be remarkably different than those of bulk water. Water confined in nanotubes and graphene sheets has been extensively investigated theoretically, yet very few computational efforts have been made to study confined water in fullerenes though, experimentally, water molecules have been successfully encapsulated inside fullerenes as small as C60. In this work, we carry out classical molecular dynamics simulations to investigate density and H-bond distributions inside fullerenes ranging from C60 to C540. Our results show that as the size of the fullerene increases, concentric shells of water molecules are formed, and the water density is higher than that of bulk water while the average H-bond per molecule is slightly lower than the bulk value. We also find that these shells of H2O are solid-like at room temperature, but they should eventually become liquid-like at high temperatures.

  17. Photodynamic Therapy with Blended Conducting Polymer/Fullerene Nanoparticle Photosensitizers.

    PubMed

    Doshi, Mona; Gesquiere, Andre J

    2015-01-01

    In this article a method for the fabrication and reproducible in-vitro evaluation of conducting polymer nanoparticles blended with fullerene as the next generation photosensitizers for Photodynamic Therapy (PDT) is reported. The nanoparticles are formed by hydrophobic interaction of the semiconducting polymer MEH-PPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]) with the fullerene PCBM (phenyl-C61-butyric acid methyl ester) in the presence of a non-compatible solvent. MEH-PPV has a high extinction coefficient that leads to high rates of triplet formation, and efficient charge and energy transfer to the fullerene PCBM. The latter processes enhance the efficiency of the PDT system through fullerene assisted triplet and radical formation, and ultrafast deactivation of MEH-PPV excited stated. The results reported here show that this nanoparticle PDT sensitizing system is highly effective and shows unexpected specificity to cancer cell lines. PMID:26556528

  18. Role of Conformation in - Interactions and Polymer/Fullerene Miscibility

    SciTech Connect

    Sumpter, Bobby G; Bucknall, David G.; Thio, Yonathan S; Gurun, Bilge; Campbell, Katie

    2011-01-01

    The origin of the miscibility between C60 fullerene and a series of phenylic vinyl polymers has been investigate using a combination of wide-angle x-ray (WAXS) and neutron (WANS) scattering and density functional theory (DFT) computational modeling. The solubility limit of the C60 in the polymers was found to increase non-linearly with increasing phenylic groups in the side-chain from 1 wt% in polystyrene (PS) to 12 wt% in poly(9-vinyl phenanthrene) (P9VPh). The DFT calculations showed that the polymer interacts with the fullerene preferentially with the phenylic groups in these vinyl polymers. However, due to the backbone these phenyl groups are unable to form the energetically favorable T-junction or planar - stacks with the fullerene, and are randomly oriented to the cage. The non-linear increase in solubility is believed to be associated with shape conformity of the three ring phenanthrene to the curvature of the fullerene.

  19. Metal Evaporation-Induced Degradation of Fullerene Acceptors in Polymer/Fullerene Solar Cells.

    PubMed

    Huang, Wenchao; Gann, Eliot; Thomsen, Lars; Tadich, Anton; Cheng, Yi-Bing; McNeill, Christopher R

    2016-01-27

    Surface-sensitive NEXAFS spectroscopy is used to probe the interaction between low work function metal electrodes and fullerene derivatives in organic solar cells. Evaporation of either Ca or Al electrodes onto films of the fullerene derivatives (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) and indene-C60 bisadduct (ICBA) leads to a dramatic change in the observed NEXAFS spectrum. The observed changes cannot be explained only in terms of interfacial electronic doping or charge transfer, but rather point to the formation of new chemical bonds that destroy the extensive electron delocalization on the C60 cage. A combination of ex situ and in situ ultrahigh vacuum measurements indicates that metal evaporation results in a change in the electronic structure of PCBM that then facilitates chemical degradation and oxidation in the presence of oxygen. To investigate the effect of this chemical interaction on device performance, a unique transfer method to laminate the Al electrode to the top of polymer blend is used, in which case, the chemical degradation of the fullerene is not observed. Device performance of P3HT/PCBM blend solar cells in which the top metal electrode has either been thermally evaporated or transferred is then compared. These results highlight that chemical, as well as electronic, interactions between metals and organic semiconductors must be considered. PMID:26683586

  20. Polynuclear aromatic hydrocarbons for fullerene synthesis in flames

    DOEpatents

    Alford, J. Michael; Diener, Michael D.

    2006-12-19

    This invention provides improved methods for combustion synthesis of carbon nanomaterials, including fullerenes, employing multiple-ring aromatic hydrocarbon fuels selected for high carbon conversion to extractable fullerenes. The multiple-ring aromatic hydrocarbon fuels include those that contain polynuclear aromatic hydrocarbons. More specifically, multiple-ring aromatic hydrocarbon fuels contain a substantial amount of indene, methylnapthalenes or mixtures thereof. Coal tar and petroleum distillate fractions provide low cost hydrocarbon fuels containing polynuclear aromatic hydrocarbons, including without limitation, indene, methylnapthalenes or mixtures thereof.

  1. Nanoscale surface structuring during ion bombardment of elemental semiconductors

    NASA Astrophysics Data System (ADS)

    Anzenberg, Eitan

    2013-01-01

    Nano-patterning of surfaces with uniform ion bombardment yields a rich phase-space of topographic patterns. Particle irradiation can cause surface ultra-smoothing or self-organized nanoscale pattern formation in surface topography. Topographic pattern formation has previously been attributed to the effects of the removal of target atoms by sputter erosion. In this thesis, the surface morphology evolution of Si(100) and Ge(100) during low energy ion bombardment of Ar+ and Kr+ ions, respectively, is studied. Our facilities for studies of surface processes at the National Synchrotron Light Source (NSLS) allow in-situ characterization of surface morphology evolution during ion bombardment using grazing incidence small angle x-ray scattering (GISAXS). This technique is used to measure in reciprocal space the kinetics of formation or decay of correlated nanostructures on the surface, effectively measuring the height-height correlations. A linear model is used to characterize the early time kinetic behavior during ion bombardment as a function of ion beam incidence angle. The curvature coefficients predicted by the widely used erosive model of Bradley and Harper are quantitatively negligible and of the wrong sign when compared to the observed effect in both Si and Ge. A mass-redistribution model explains the observed ultra-smoothing at low angles, exhibits an instability at higher angles, and predicts the observed 45 critical angle separating these two regimes in Si. The Ge surface evolution during Kr+ irradiation is qualitatively similar to that observed for Ar+ irradiation of Si at the same ion energy. However, the critical angle for Ge cannot be quantitatively reproduced by the simple mass redistribution model. Crater function theory, as developed by Norris et al., incorporates both mass redistributive and erosive effects, and predicts constraining relationships between curvature coefficients. These constraints are compared to experimental data of both Si and Ge. There is good agreement at low incidence angles; however, at higher angles the data disagrees with the predictions of the crater function formalism. This calls into question the ability of crater function theory to model the surface morphology evolution during ion bombardment.

  2. Optical heating and rapid transformation of functionalized fullerenes.

    PubMed

    Krishna, Vijay; Stevens, Nathanael; Koopman, Ben; Moudgil, Brij

    2010-05-01

    Irradiating single-walled carbon nanotubes can lead to heat generation or ignition. These processes could be used in medical and industrial applications, but the poor solvent compatibility and high aspect ratios of nanotubes have led to concerns about safety. Here, we show that certain functionalized fullerenes, including polyhydroxy fullerenes (which are known to be environmentally safe and to have therapeutic properties) are heated or ignited by exposure to low-intensity (<10(2 ) W cm(-2)) continuous-wave laser irradiation. We also show that polyhydroxy fullerenes and other functionalized fullerenes can be transformed into single-walled nanotubes, multiwalled nanotubes and carbon onions without the presence of a catalyst by exposure to low-intensity laser irradiation in an oxygen-free environment. To demonstrate the potential usefulness of these processes in applications, we disrupted animal cells dosed with polyhydroxy fullerenes by exposing them to a near-infrared laser for a few seconds, and also ignited an explosive charge in contact with a particle of carboxy fullerenes. PMID:20228785

  3. Fullerene derivatives protect endothelial cells against NO-induced damage.

    PubMed

    Lao, Fang; Li, Wei; Han, Dong; Qu, Ying; Liu, Ying; Zhao, Yuliang; Chen, Chunying

    2009-06-01

    Functional fullerene derivatives have been demonstrated with potent antioxidation properties. Nitric oxide (NO) is a free radical that plays a part in leading to brain damage when it is accumulated to a high concentration. The possible scavenging activity of NO by the hydroxylated fullerene derivative C60(OH)22 and malonic acid derivative C60(C(COOH)2)2 was investigated using primary rat brain cerebral microvessel endothelial cells (CMECs). Results demonstrate that sodium nitroprusside (SNP), used as an NO donor, caused a marked decrease in cell viability and an increase in apoptosis. However, fullerene derivatives can remarkably protect against the apoptosis induced by NO assault. In addition, fullerene derivatives can also prevent NO-induced depolymerization of cytoskeleton and damage of the nucleus and accelerate endothelial cell repair. Further investigation shows that the sudden increase of the intercellular reactive oxygen species (ROS) induced by NO was significantly attenuated by post-treatment with fullerene derivatives. Our results suggest that functional fullerene derivatives are potential applications for NO-related disorders. PMID:19433873

  4. Fullerenes and interplanetary dust at the Permian-Triassic boundary.

    PubMed

    Poreda, Robert J; Becker, Luann

    2003-01-01

    We recently presented new evidence that an impact occurred approximately 250 million years ago at the Permian-Triassic boundary (PTB), triggering the most severe mass extinction in the history of life on Earth. We used a new extraterrestrial tracer, fullerene, a third carbon carrier of noble gases besides diamond and graphite. By exploiting the unique properties of this molecule to trap noble gases inside of its caged structure (helium, neon, argon), the origin of the fullerenes can be determined. Here, we present new evidence for fullerenes with extraterrestrial noble gases in the PTB at Graphite Peak, Antarctica, similar to PTB fullerenes from Meishan, China and Sasayama, Japan. In addition, we isolated a (3)He-rich magnetic carrier phase in three fractions from the Graphite Peak section. The noble gases in this magnetic fraction were similar to zero-age deep-sea interplanetary dust particles (IDPs) and some magnetic grains isolated from the Cretaceous-Tertiary boundary. The helium and neon isotopic compositions for both the bulk Graphite Peak sediments and an isolated magnetic fraction from the bulk material are consistent with solar-type gases measured in zero-age deep-sea sediments and point to a common source, namely, the flux of IDPs to the Earth's surface. In this instance, the IDP noble gas signature for the bulk sediment can be uniquely decoupled from fullerene, demonstrating that two separate tracers are present (direct flux of IDPs for (3)He vs. giant impact for fullerene). PMID:12804366

  5. Persistent Homology for The Quantitative Prediction of Fullerene Stability

    PubMed Central

    Xia, Kelin; Feng, Xin; Tong, Yiying; Wei, Guo Wei

    2014-01-01

    Persistent homology is a relatively new tool often used for qualitative analysis of intrinsic topological features in images and data originated from scientific and engineering applications. In this paper, we report novel quantitative predictions of the energy and stability of fullerene molecules, the very first attempt in employing persistent homology in this context. The ground-state structures of a series of small fullerene molecules are first investigated with the standard Vietoris-Rips complex. We decipher all the barcodes, including both short-lived local bars and long-lived global bars arising from topological invariants, and associate them with fullerene structural details. By using accumulated bar lengths, we build quantitative models to correlate local and global Betti-2 bars respectively with the heat of formation and total curvature energies of fullerenes. It is found that the heat of formation energy is related to the local hexagonal cavities of small fullerenes, while the total curvature energies of fullerene isomers are associated with their sphericities, which are measured by the lengths of their long-lived Betti-2 bars. Excellent correlation coefficients (> 0.94) between persistent homology predictions and those of quantum or curvature analysis have been observed. A correlation matrix based filtration is introduced to further verify our findings. PMID:25523342

  6. Detection and separation of radioactive fullerene families by radiochemical techniques

    NASA Astrophysics Data System (ADS)

    Ohtsuki, T.; Masumoto, K.; Sueki, K.; Kikuchi, K.; Ohno, K.; Maruyama, Y.; Kawazoe, Y.

    1997-06-01

    Radioactive fullerenes labeled with 11C and its derivatives; such as the fullerene dimers and trimers, were produced by photonuclear and charged particle reactions and isolated in a liquid phase by radiochromatography. The 11C nuclide exists in fullerene cages to extend of about 60-70% of the total amount of 11C produced when the C60 sample was irradiated. Also, radioactive endohedral 7Be@C60, 7Be@C70 can be detected using radiochemical techniques in the final solvent. Such a 7Be atom can penetrate into the fullerene cage to produce 7Be@C60, 7Be@C70 by a recoil process of the nuclear reactions. An ab initio molecular dynamics simulation was carried out to demonstrate that a direct insertion process is really possible. Both the experimental and the theoretical results were consistent with each other. This successful production of radioactive fullerenes demonstrates the structural stability and/or flexibility of fullerene cages.

  7. Photodynamic therapy with fullerenes in vivo: reality or a dream?

    PubMed Central

    Sharma, Sulbha K; Chiang, Long Y; Hamblin, Michael R

    2012-01-01

    Photodynamic therapy (PDT) employs the combination of nontoxic photosensitizers and visible light that is absorbed by the chromophore to produce long-lived triplet states that can carry out photochemistry in the presence of oxygen to kill cells. The closed carbon-cage structure found in fullerenes can act as a photosensitizer, especially when functionalized to impart water solubility. Although there are reports of the use of fullerenes to carry out light-mediated destruction of viruses, microorganisms and cancer cells in vitro, the use of fullerenes to mediate PDT of diseases such as cancer and infections in animal models is less well developed. It has recently been shown that fullerene PDT can be used to save the life of mice with wounds infected with pathogenic Gram-negative bacteria. Fullerene PDT has also been used to treat mouse models of various cancers including disseminated metastatic cancer in the peritoneal cavity. In vivo PDT with fullerenes represents a new application in nanomedicine. PMID:22122587

  8. Effects of Two Fullerene Derivatives on Monocytes and Macrophages

    PubMed Central

    Pacor, Sabrina; Grillo, Alberto; Đorđević, Luka; Zorzet, Sonia; Da Ros, Tatiana; Prato, Maurizio

    2015-01-01

    Two fullerene derivatives (fullerenes 1 and 2), bearing a hydrophilic chain on the pyrrolidinic nitrogen, were developed with the aim to deliver anticancer agents to solid tumors. These two compounds showed a significantly different behaviour on human neoplastic cell lines in vitro in respect to healthy leukocytes. In particular, the pyrrolidinium ring on the fullerene carbon cage brings to a more active compound. In the present work, we describe the effects of these fullerenes on primary cultures of human monocytes and macrophages, two kinds of immune cells representing the first line of defence in the immune response to foreign materials. These compounds are not recognized by circulating monocytes while they get into macrophages. The evaluation of the pronecrotic or proapoptotic effects, analysed by means of analysis of the purinergic receptor P2X7 activation and of ROS scavenging activity, has allowed us to show that fullerene 2, but not its analogue fullerene 1, displays toxicity, even though at concentrations higher than those shown to be active on neoplastic cells. PMID:26090460

  9. Time-resolved fluorescence studies of fullerene derivatives.

    PubMed

    Andreoni, Alessandra; Nardo, Luca; Bondani, Maria; Zhao, Baozhong; Roberts, Joan E

    2013-06-20

    Fullerene (nano-C60) and its water-soluble derivatives have several clinical applications including use as a drug carrier to bypass the blood-ocular and blood-brain barriers. However, in vitro and in vivo detection of these nanomaterials is limited by their very low fluorescence quantum yield. The accumulation of fullerene and its derivatives in cells is particularly difficult to measure using standard fluorescence microscopy because their fluorescence is barely detectable in aqueous media. We have developed a time-correlated single-photon counting apparatus with which we were not only able to detect the fluorescence of fullerene and its derivatives in water but could also measure fluorescence temporal decays and determine lifetimes in the range of tens of picoseconds. The compounds studied in this report are C60 (fullerene), the partially hydrogenated hydride C60H36, a monomeric cyclodextrin complexed fullerene [(?-CyD)2/C60], and C60(OH)24 (fullerol). In addition, we examined the effect of aggregation on photophysical properties and identified a very short lifetime component belonging to the fluorescence decay of monomeric fullerene, which is lost with increasing aggregation. These data will help to design nanoparticles that have the appropriate structural and photophysical properties to ultimately be of use in a clinical setting. PMID:23646878

  10. Histopathology of fathead minnow (Pimephales promelas) exposed to hydroxylated fullerenes

    PubMed Central

    Whitley, Elizabeth M.; Pali?, Duan

    2014-01-01

    Hydroxylated fullerenes are reported to be very strong antioxidants, acting to quench reactive oxygen species, thus having strong potential for important and widespread applications in innovative therapies for a variety of disease processes. However, their potential for toxicological side effects is still largely controversial and unknown. Effects of hydroxylated fullerenes C60(OH)24 on the fathead minnow (Pimephales promelas) were investigated microscopically after a 72-hour (acute) exposure by intraperitoneal injection of 20 ppm of hydroxylated fullerenes per gram of body mass. Cumulative, semi-quantitative histopathologic evaluation of brain, liver, anterior kidney, posterior kidney, skin, coelom, gills and the vestibuloauditory system revealed significant differences between control and hydroxylated fullerene-treated fish. Fullerene-treated fish had much higher cumulative histopathology scores. Histopathologic changes included loss of cellularity in the interstitium of the kidney, a primary site of haematopoiesis in fish, and loss of intracytoplasmic glycogen in liver. In the coelom, variable numbers of leukocytes, including many macrophages and fewer heterophils and rodlet cells, were admixed with the nanomaterial. These findings raise concern about in vivo administration of hydroxylated fullerenes in experimental drugs and procedures in human medicine, and should be investigated in more detail. PMID:23883179

  11. Binding of fullerenes to amyloid beta fibrils: size matters.

    PubMed

    Huy, Pham Dinh Quoc; Li, Mai Suan

    2014-10-01

    Binding affinity of fullerenes C20, C36, C60, C70 and C84 for amyloid beta fibrils is studied by docking and all-atom molecular dynamics simulations with the Amber force field and water model TIP3P. Using the molecular mechanic-Poisson Boltzmann surface area method one can demonstrate that the binding free energy linearly decreases with the number of carbon atoms of fullerene, i.e. the larger is the fullerene size, the higher is the binding affinity. Overall, fullerenes bind to A?9-40 fibrils stronger than to A?17-42. The number of water molecules trapped in the interior of 12A?9-40 fibrils was found to be lower than inside pentamer 5A?17-42. C60 destroys A?17-42 fibril structure to a greater extent compared to other fullerenes. Our study revealed that the van der Waals interaction dominates over the electrostatic interaction and non-polar residues of amyloid beta peptides play the significant role in interaction with fullerenes providing novel insight into the development of drug candidates against Alzheimer's disease. PMID:25123396

  12. Optical heating and rapid transformation of functionalized fullerenes

    NASA Astrophysics Data System (ADS)

    Krishna, Vijay; Stevens, Nathanael; Koopman, Ben; Moudgil, Brij

    2010-05-01

    Irradiating single-walled carbon nanotubes can lead to heat generation or ignition. These processes could be used in medical and industrial applications, but the poor solvent compatibility and high aspect ratios of nanotubes have led to concerns about safety. Here, we show that certain functionalized fullerenes, including polyhydroxy fullerenes (which are known to be environmentally safe and to have therapeutic properties) are heated or ignited by exposure to low-intensity (<102 W cm-2) continuous-wave laser irradiation. We also show that polyhydroxy fullerenes and other functionalized fullerenes can be transformed into single-walled nanotubes, multiwalled nanotubes and carbon onions without the presence of a catalyst by exposure to low-intensity laser irradiation in an oxygen-free environment. To demonstrate the potential usefulness of these processes in applications, we disrupted animal cells dosed with polyhydroxy fullerenes by exposing them to a near-infrared laser for a few seconds, and also ignited an explosive charge in contact with a particle of carboxy fullerenes.

  13. High resolution NMR of rubidium doped fullerenes

    SciTech Connect

    Zahab, A.; Bernier, P.; Firlej, L.

    1992-12-01

    The authors have used High Resolution {sup 13}C NMR (50.3 MHz) to study the structural and electronic properties of Rubidium doped Fullerenes. An anisotropic Knight shift is generally observed whose extend ({approximately} 40 ppm) and isotropic part value ({approximately} 42 ppm) do not depend on the stoichiometry of the compound. The resonance linewidth drastically increases by a factor of 10 between room temperature and 150 K, showing that the rotational motion of the individual C{sub 60} is severely hindered at low temperature. The relaxational time T{sub 1}({approximately} 70 ms at room temperature) roughly follows a law T{sub 1}T = constant, usual in the case of normal metal. All the results are discussed on the light of existing structural and electronic models for these compounds.

  14. Fullerene Embedded Shape Memory Nanolens Array

    PubMed Central

    Jeon, Sohee; Jang, Jun Young; Youn, Jae Ryoun; Jeong, Jun-ho; Brenner, Howard; Song, Young Seok

    2013-01-01

    Securing fragile nanostructures against external impact is indispensable for offering sufficiently long lifetime in service to nanoengineering products, especially when coming in contact with other substances. Indeed, this problem still remains a challenging task, which may be resolved with the help of smart materials such as shape memory and self-healing materials. Here, we demonstrate a shape memory nanostructure that can recover its shape by absorbing electromagnetic energy. Fullerenes were embedded into the fabricated nanolens array. Beside the energy absorption, such addition enables a remarkable enhancement in mechanical properties of shape memory polymer. The shape memory nanolens was numerically modeled to impart more in-depth understanding on the physics regarding shape recovery behavior of the fabricated nanolens. We anticipate that our strategy of combining the shape memory property with the microwave irradiation feature can provide a new pathway for nanostructured systems able to ensure a long-term durability. PMID:24253423

  15. Fullerene Embedded Shape Memory Nanolens Array

    NASA Astrophysics Data System (ADS)

    Jeon, Sohee; Jang, Jun Young; Youn, Jae Ryoun; Jeong, Jun-Ho; Brenner, Howard; Song, Young Seok

    2013-11-01

    Securing fragile nanostructures against external impact is indispensable for offering sufficiently long lifetime in service to nanoengineering products, especially when coming in contact with other substances. Indeed, this problem still remains a challenging task, which may be resolved with the help of smart materials such as shape memory and self-healing materials. Here, we demonstrate a shape memory nanostructure that can recover its shape by absorbing electromagnetic energy. Fullerenes were embedded into the fabricated nanolens array. Beside the energy absorption, such addition enables a remarkable enhancement in mechanical properties of shape memory polymer. The shape memory nanolens was numerically modeled to impart more in-depth understanding on the physics regarding shape recovery behavior of the fabricated nanolens. We anticipate that our strategy of combining the shape memory property with the microwave irradiation feature can provide a new pathway for nanostructured systems able to ensure a long-term durability.

  16. Fullerene embedded shape memory nanolens array.

    PubMed

    Jeon, Sohee; Jang, Jun Young; Youn, Jae Ryoun; Jeong, Jun-Ho; Brenner, Howard; Song, Young Seok

    2013-01-01

    Securing fragile nanostructures against external impact is indispensable for offering sufficiently long lifetime in service to nanoengineering products, especially when coming in contact with other substances. Indeed, this problem still remains a challenging task, which may be resolved with the help of smart materials such as shape memory and self-healing materials. Here, we demonstrate a shape memory nanostructure that can recover its shape by absorbing electromagnetic energy. Fullerenes were embedded into the fabricated nanolens array. Beside the energy absorption, such addition enables a remarkable enhancement in mechanical properties of shape memory polymer. The shape memory nanolens was numerically modeled to impart more in-depth understanding on the physics regarding shape recovery behavior of the fabricated nanolens. We anticipate that our strategy of combining the shape memory property with the microwave irradiation feature can provide a new pathway for nanostructured systems able to ensure a long-term durability. PMID:24253423

  17. Synthesis separation characterization of partially reduced fullerenes

    SciTech Connect

    Meier, M.S.; Selegue, J.P.; Vance, V.K.; Corbin, P.L.

    1993-12-31

    The Birch reduction of C{sub 60} is known to result in the formation of C{sub 60}H{sub 36}. The authors have investigated the reduction of C{sub 60} using much less powerful reducing conditions. Specifically, the authors have investigated partial hydrogenation and zinc/acid reductions under a variety of conditions. Regardless of the conditions, the same series of three products as determined by gel-permeation chromatography (GPC) was obtained. The authors have used preparative GPC to isolate these bands and have investigated their chromatographic behavior, absorption spectra, and mass spectrometry. In this talk the synthesis, separation, and characterization of these compounds will be presented, and discuss the possible structures of these partially reduced fullerenes.

  18. Defect-induced ferromagnetism in fullerenes

    NASA Astrophysics Data System (ADS)

    Boukhvalov, D. W.; Katsnelson, M. I.

    2009-04-01

    Based on the ab initio electronic structure calculations the picture of ferromagnetism in polimerized C60 is proposed which seems to explain the whole set of controversial experimental data. We have demonstrated that, in contrast with cubic fullerene, in rhombohedral C60 the segregation of iron atoms is energetically unfavorable which is a strong argument in favor of intrinsic character of carbon ferromagnetism which can be caused by vacancies with unpaired magnetic electrons. It is shown that: (i) energy formation of the vacancies in the rhombohedral phase of C60 is essentially smaller than in the cubic phase, (ii) there is a strong ferromagnetic exchange interactions between carbon cages containing the vacancies, (iii) presence of iron impurities can diminish essentially the formation energy of intrinsic defects, and (iv) the fusion of the magnetic single vacancies into nonmagnetic bivacancies is energetically favorable. The latter can explain a fragility of the ferromagnetism.

  19. Mixing of binary metal systems by noble-gas ions of energies between 30 and 400 keV

    NASA Astrophysics Data System (ADS)

    Hiller, W.; Buchgeister, M.; Eitner, P.; Kopitzki, K.; Lilienthal, V.; Mertler, G.

    1990-03-01

    Multilayered samples of the binary systems Au-Rh and Ni-Pt were bombarded at 77 K with He-, Ne-, Ar- and Kr-ions at energies between 30 and 400 keV. The maximum irradiation dose was 2 1017 ions/cm2. All samples were analysed by X-ray diffraction using a Seemann-Bohlin arrangement. In thermal equilibrium the system Au-Rh has vanishingly small mutual solid solubility whereas the phase diagram of the system Ni-Pt shows that the two metals form a continuous series of solid solutions. By irradiation of Au-Rh samples with Kr-ions a single-phase metastable solid solution was produced. Irradiation with Ar- and Ne-ions results in extension of the terminal solid solubilities. Irradiation with 400 keV He-ions did not cause any mixing. This is in contrast to the experiments with 30 keV He-ions for which we could observe partial mixing. By ion irradiation of Ni-Pt samples solid solutions were produced in all cases. The results are discussed in the frame of the thermal spike model of ion beam mixing.

  20. Cage connectivity and frontier ? orbitals govern the relative stability of charged fullerene isomers

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Daz-Tendero, Sergio; Alcam, Manuel; Martn, Fernando

    2015-11-01

    Fullerene anions and cations have unique structural, electronic, magnetic and chemical properties that make them substantially different from neutral fullerenes. Although much theoretical effort has been devoted to characterizing and predicting their properties, this has been limited to a fraction of isomeric forms, mostly for fullerene anions, and has practically ignored fullerene cations. Here we show that the concepts of cage connectivity and frontier ? orbitals allow one to understand the relative stability of charged fullerene isomers without performing elaborate quantum chemistry calculations. The latter is not a trivial matter, as the number of possible isomers for a medium-sized fullerene is many more than 100,000. The model correctly predicts the structures observed experimentally and explains why the isolated pentagon rule is often violated for fullerene anions, but the opposite is found for fullerene cations. These predictions are relevant in fields as diverse as astrophysics, electrochemistry and supramolecular chemistry.

  1. Cage connectivity and frontier ? orbitals govern the relative stability of charged fullerene isomers.

    PubMed

    Wang, Yang; Daz-Tendero, Sergio; Alcam, Manuel; Martn, Fernando

    2015-11-01

    Fullerene anions and cations have unique structural, electronic, magnetic and chemical properties that make them substantially different from neutral fullerenes. Although much theoretical effort has been devoted to characterizing and predicting their properties, this has been limited to a fraction of isomeric forms, mostly for fullerene anions, and has practically ignored fullerene cations. Here we show that the concepts of cage connectivity and frontier ? orbitals allow one to understand the relative stability of charged fullerene isomers without performing elaborate quantum chemistry calculations. The latter is not a trivial matter, as the number of possible isomers for a medium-sized fullerene is many more than 100,000. The model correctly predicts the structures observed experimentally and explains why the isolated pentagon rule is often violated for fullerene anions, but the opposite is found for fullerene cations. These predictions are relevant in fields as diverse as astrophysics, electrochemistry and supramolecular chemistry. PMID:26492014

  2. Photophysical Properties and Singlet Oxygen Generation Efficiencies of Water-Soluble Fullerene Nanoparticles

    PubMed Central

    Stasheuski, Alexander S; Galievsky, Victor A; Stupak, Alexander P; Dzhagarov, Boris M; Choi, Mi Jin; Chung, Bong Hyun; Jeong, Jin Young

    2014-01-01

    As various fullerene derivatives have been developed, it is necessary to explore their photophysical properties for potential use in photoelectronics and medicine. Here, we address the photophysical properties of newly synthesized water-soluble fullerene-based nanoparticles and polyhydroxylated fullerene as a representative water-soluble fullerene derivative. They show broad emission band arising from a wide-range of excitation energies. It is attributed to the optical transitions from disorder-induced states, which decay in the nanosecond time range. We determine the kinetic properties of the singlet oxygen (1O2) luminescence generated by the fullerene nanoparticles and polyhydroxylated fullerene to consider the potential as photodynamic agents. Triplet state decay of the nanoparticles was longer than 1O2 lifetime in water. Singlet oxygen quantum yield of a series of the fullerene nanoparticles is comparably higher ranging from 0.15 to 0.2 than that of polyhydroxylated fullerene, which is about 0.06. PMID:24893622

  3. Plasma etching of high-resolution features in a fullerene molecular resist

    NASA Astrophysics Data System (ADS)

    Manyam, J.; Manickam, M.; Preece, J. A.; Palmer, R. E.; Robinson, A. P. G.

    2011-04-01

    As resist films become thinner, so as to reduce problems of aspect ratio related pattern collapse at high-resolution, it is becoming increasingly difficult to transfer patterns with useful aspect ratio by directly etching the resist. It has become common to use the photoresist to pattern an intermediate hardmask, which then protects the silicon substrate during etching, allowing useful aspect ratios but adding process complexity. We have previously described a fullerene based electron beam lithography resist capable of 20 nm halfpitch and 12 nm sparse features, at a sensitivity of less than 10 ?C/cm2 at 20 keV. The fullerene resist has high etch durability - comparable to that of commercial novolac resists - and has previously demonstrated an etch selectivity of 3:1 to silicon using electron cyclotron resonance microwave plasma etching with SF6. Here a study of the capabilities of this resist when using Inductively Coupled Plasma etching is presented. Line-space patterns with half-pitches in the range 25 nm to 100 nm, together with sparse features (~20 nm linewidth on a 200 nm pitch) were produced in ~30 nm thick resist films using electron beam lithography, and transferred to silicon using an inductively coupled plasma etcher. Several combinations of SF6, CF4, CHF3 and C4F8process gases were explored. Etch selectivity and anisotropy were studied as a range of etching parameters, such as ICP and RF power, gas flow rate, pressure and temperature were varied. Etch selectivities in excess of 9:1 were demonstrated. Techniques for minimizing aspect ratio dependent etching effects in dense features, including the use of ashing or high etching pressures were also examined.

  4. Dynamics Constraints and Modeling of the Late Heavy Bombardment

    NASA Astrophysics Data System (ADS)

    Morbidelli, Alessandro

    2007-10-01

    The existence of a cataclysmic spike in the bombardment rate of the Moon 3.8 Gy ago, roughly 650 My after the formation of the terrestrial planets, was once considered implausible from the dynamical point of view. This led many to favor a 650 My long declining bombardment to explain the Moon's early crater history. Interestingly, this situation has been reversed over the several last years. Dynamical studies now show the bombardment rate was unlikely to remain high over such a long interval. Instead, insights gleaned from our improved understanding of giant planet formation and migration in planetesimal disks suggest that the Jovian planets experienced a late, sudden instability as they crossed some mutual resonance. This triggered a rapid depletion of the trans-Neptunian planetesimal disk and caused an acceleration of the migration of Jupiter and Saturn, which in turn destabilized the majority of the asteroids in the main belt. The so-called `Nice model' built on this idea not only explains the main characteristics of the impact spike in terms of delay, intensity and duration, but also the current orbital architecture of the giant planets,the existence and the orbital distribution of many populations of small bodies (trojans, KBOs, satellites). Moreover, it is consistent with recent work on the size distribution of lunar craters at the time of the LHB, which shows that main belt asteroids, ejected from the main belt by a size-independent process, formed most of the Moon's oldest craters. We briefly review and discuss also alternative scenarios.

  5. Effects Produced in Gallium-Arsenide by Mev Ion Bombardment

    NASA Astrophysics Data System (ADS)

    Wie, Chu Ryang

    Presented in the first part of this thesis is work performed on the ionizing energy beam induced adhesion enhancement of thin ((TURN)500 Angstrom) Au films on GaAs substrates. The ionizing beam, employed in the present thesis, is the MeV ions (i.e., ('16)O, ('19)F, and ('35)Cl), with energies between 1 and 20 MeV. Using the "Scratch" test for adhesion measurement, and ESCA for chemical analysis of the film-substrate interface, the native oxide layer at the interface is shown to play an important role in the adhesion enhancement by the ionizing radiation. A model is discussed which explains the experimental data on the dependence of adhesion enhancement on the energy which was deposited into electronic processes at the interface. The ESCA data indicate that the chemical bonds (or compounds), which are responsible for the increase in the thin film adherence, are hydroxides rather than oxides. In the second part of the thesis we present a research performed on the radiation damage in GaAs crystals produced by MeV ions. Lattice parameter dilatation in the surface layers of the GaAs crystals becomes saturated after a high dose bombardment at room temperature. The strain produced by nuclear collisions is shown to relax partially due to electronic excitation (with a functional dependence on the nuclear and electronic stopping power of bombarding ions). Data on the GaAs and GaP crystals suggest that low temperature recovery stage defects produce major crystal distortion. The x-ray rocking curve technique with a dynamical diffraction theory analysis provides the depth distribution of the strain and damage in the MeV ion bombarded crystals.

  6. Single impact crater functions for ion bombardment of silicon

    SciTech Connect

    Kalyanasundaram, N.; Ghazisaeidi, M.; Freund, J. B.; Johnson, H. T.

    2008-03-31

    The average effect of a single 500 eV incident argon ion on a silicon surface is studied using molecular dynamics simulations. More than 10{sup 3} ion impacts at random surface points are averaged for each of seven incidence angles, from 0 deg. to 28 deg. off normal, to determine a local surface height change function, or a crater function. The crater shapes are mostly determined by mass rearrangement; sputtering has a relatively small effect. Analytical fitting functions are provided for several cases, and may serve as input into kinetic Monte Carlo calculations or stability analyses for surfaces subjected to ion bombardment.

  7. Exploring the Early Bombardment of the Inner Solar System

    NASA Astrophysics Data System (ADS)

    Bottke, W.

    2014-04-01

    The early bombardment history of the Inner Solar System is recorded in a number of interesting places (e.g., the surprisingly high abundance of highly siderophile abundances found in the Earth, Moon, and Mars, the observed impact basins found on Mercury, the Moon and Mars, various properties of main belt asteroids and meteorites, etc.). To date, two dominant scenarios have been used to explain these constraints: (i) most impacts came from the tail end of a monotonically-decreasing impactor population created by planet formation processes, and (ii) most impacts were produced by a terminal cataclysm that caused a spike in the impactor flux starting ~4 Gy ago. Interestingly, using numerical studies linked to the available constraints, we find that both scenarios are needed to explain observations. For (i), we will show that leftover planetesimals from the terrestrial planet region were long-lived enough to hit various worlds long after the end of core formation. The record left behind can be used in interesting ways to probe the nature of terrestrial planet formation. For (ii), we will explore new applications of the so-called Nice model, which provides a plausible dynamical mechanism capable of creating a spike of comets/asteroid impactors. Our results suggest that many "late heavy bombardment" impactors came from an unexpected source, and that they possibly continued to hit Earth, Venus, and Mars well after basin formation terminated on the Moon. Interestingly, the history of the Hadean Earth (ca. 4.0-4.5 billion years ago) may be closely linked to this bombardment. With few known rocks older than ~3.8 Ga, the main constraints from this era come from ancient submillimeter zircon grains. Using our bombardment model, we will argue that the surface of the Hadean Earth was widely reprocessed by impacts through mixing and heating of its uppermost layers. This model not only may explains the Pb-Pb age distribution of ancient zircons but also the absence of most early terrestrial rocks. We predict life originating in the Hadean would need to be both hardy and mobile enough to survive these extreme conditions.

  8. Continuous-flow fast atom bombardment: recent advances and applications

    NASA Astrophysics Data System (ADS)

    Caprioli, Richard M.; Suter, Marc J.-F.

    1992-09-01

    Continuous-flow fast atom bombardment is a sensitive ionization technique for the analysis of charged and polar organic molecules. Advances in probe design have led to extremely stable operating conditions over many hours of use. The on-line capability of the technique for the introduction of flow-injected samples, effluent from separation techniques such as high performance liquid chromatography, capillary electrophoresis or microdialysis, remains a major advantage. Spectral interpretation is facilitated by the production of singly-charged species, giving the technique a useful mass range up to about 6000 u. Examples of applications are provided to illustrate the scope and utility of the technique in biological research.

  9. Electron-bombarded CCD detectors for ultraviolet atmospheric remote sensing

    NASA Technical Reports Server (NTRS)

    Carruthers, G. R.; Opal, C. B.

    1983-01-01

    Electronic image sensors based on charge coupled devices operated in electron-bombarded mode, yielding real-time, remote-readout, photon-limited UV imaging capability are being developed. The sensors also incorporate fast-focal-ratio Schmidt optics and opaque photocathodes, giving nearly the ultimate possible diffuse-source sensitivity. They can be used for direct imagery of atmospheric emission phenomena, and for imaging spectrography with moderate spatial and spectral resolution. The current state of instrument development, laboratory results, planned future developments and proposed applications of the sensors in space flight instrumentation is described.

  10. Enhanced resistance of single-layer graphene to ion bombardment

    SciTech Connect

    Lopez, J. J.; Greer, F.; Greer, J. R.

    2010-05-15

    We report that single-layer graphene on a SiO{sub 2}/Si substrate withstands ion bombardment up to {approx}7 times longer than expected when exposed to focused Ga{sup +} ion beam. The exposure is performed in a dual beam scanning electron microscope/focused ion beam system at 30 kV accelerating voltage and 41 pA current. Ga{sup +} ion flux is determined by sputtering a known volume of hydrogenated amorphous carbon film deposited via plasma-enhanced chemical vapor deposition.

  11. Fullerene antioxidants decrease organophosphate-induced acetylcholinesterase inhibition in vitro.

    PubMed

    Ehrich, Marion; Van Tassell, Roger; Li, Yunbo; Zhou, Zhiguo; Kepley, Chris L

    2011-02-01

    Although organophosphate (OP)-induced acetylcholinesterase (AChE) inhibition is the critical mechanism causing toxicities that follow exposure, other biochemical events, including oxidative stress, have been reported to contribute to OP toxicity. Fullerenes are carbon spheres with antioxidant activity. Thus, we hypothesized that fullerenes could counteract the effects of OP compounds and tested this hypothesis using two in vitro test systems, hen brain and human neuroblastoma SH-SY5Y cells. Cells were incubated with eight different derivatized fullerene compounds before challenge with paraoxon (0=control, 510(-8), 10(-7), 210(-7) or 510(-7) M) or diisopropylphosphorofluoridate (DFP, 0=control, 510(-6), 10(-5), 210(-5), and 510(-5) M) and measurement of AChE activities. Activities of brain and SH-SY5Y AChE with OP compounds alone ranged from 55-83% lower than non-treated controls after paraoxon and from 60-92% lower than non-treated controls after DFP. Most incubations containing 1 and 10 ?M fullerene derivatives brought AChE activity closer to untreated controls, with improvements in AChE activity often >20%. Using dissipation of superoxide anion radicals as an indicator (xanthine oxidation as a positive control), all fullerene derivatives demonstrated significant antioxidant capability in neuroblastoma cells at 1 ?M concentrations. No fullerene derivative at 1 ?M significantly affected neuroblastoma cell viability, when determined using either Alamar Blue dye retention or a luminescent assay for ATP production. These studies suggest that derivatized fullerene nanomaterials have potential capability to ameliorate OP-induced AChE inhibition resulting in toxicities. PMID:20888407

  12. The study of dielectric properties of the endohedral fullerenes

    NASA Astrophysics Data System (ADS)

    Bhusal, Shusil

    Dielectric response of the metal nitride fullerenes is studied using the density functional theory at the all-electron level using generalized gradient approximation. The dielectric response is studied by computing the static dipole polarizabilities using the finite field method, i.e. by numerically differentiating the dipole moments with respect to electric field. The endohedral fullerenes studied in this work are Sc3N C68(6140), Sc3N C68(6146), Sc3N C70(7854), Sc3N C70(7960), Sc3N C76(17490), Sc3N C78(22010), Sc3N C80(31923), Sc3N C80(31924), Sc3N C82(39663), Sc3N C90(43), Sc3N C90(44), Sc3N C92(85), Sc3N C94(121), Sc3N C96(186), Sc3N C98(166). Using the Voronoi and Hirschfield approaches as implemented in our NRLMOL code, we determine the atomic contributions to the total polarizability. The site-specific contributions to the polarizability of endohedral fullerenes allowed us to determine the polarizability of two subsystems: the fullerene shell and the encapsulated Sc3N unit. Our results showed that the contributions to the total polarizability from the encapsulated Sc3N units are vanishingly small. Thus, the total polarizability of the endohedral fullerene is almost entirely due to the outer fullerene shell. These fullerenes are excellent molecular models of a Faraday cage.

  13. The development of a fullerene based hydrogen storage system

    SciTech Connect

    Brosha, E.L.; Davey, J.R.; Garzon, F.H.; Gottesfeld, S.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The project objective was to evaluate hydrogen uptake by fullerene substrates and to probe the potential of the hydrogen/fullerene system for hydrogen fuel storage. As part of this project, the authors have completed and tested a fully automated, computer controlled system for measuring hydrogen uptake that is capable of handling both a vacuum of 1 x 10{sup -6} torr and pressures greater than 200 bars. The authors have first established conditions for significant uptake of hydrogen by fullerenes. Subsequently, hydrogenation and dehydrogenation of pure and catalyst-doped C60 was further studied to probe suitability for hydrogen storage applications. C60 {center_dot} H18.7 was prepared at 100 bar H2 and 400 C, corresponding to hydrogen uptake of 2.6 wt%. Dehydrogenation of C60 {center_dot} H18.7 was studied using thermogravimetric and powder x-ray diffraction analysis. The C60 {center_dot} H18.7 molecule was found to be stable up to 430 C in Ar, at which point the release of hydrogen took place simultaneously with the collapse of the fullerene structure. X-ray diffraction analysis performed on C60 {center_dot} H18.7 samples dehydrogenated at 454 C, 475 C, and 600 C showed an increasing volume fraction of amorphous material due to randomly oriented, single-layer graphine sheets. Evolved gas analysis using gas chromatography and mass spectroscopy confirmed the presence of both H{sub 2} and methane upon dehydrogenation, indicating decomposition of the fullerene. The remaining carbon could not be re-hydrogenated. These results provide the first complete evidence for the irreversible nature of fullerene hydrogenation and for limitations imposed on the hydrogenation/dehydrogenation cycle by the limited thermal stability of the molecular crystal of fullerene.

  14. Impact of physicochemical properties of engineered fullerenes on key biological responses

    SciTech Connect

    Rebecca, Martin; Hsing-Lin, Wang; Jun, Gao; Srinivas, Iyer; Gabriel, Montano A.; Jennifer, Martinez; Andrew, Shreve P.; Bao Yuping; Wang, C.-C.; Chang Zhong; Gao Yuan; Rashi, Iyer

    2009-01-01

    Engineered fullerenes are widely integrated into several commercial and medical products and are now also being recognized as byproducts of many industrial activities. For most applications fullerenes have to be chemically modified. Surface modification of fullerenes can potentially impact their effect on biosystems. The purpose of the current study was to establish criteria to correlate fullerene structure to biological responses. We report studies of cellular responses induced by three different types of fullerenes that provide varying chemical and physical properties such as electronic behavior, solubility, and degree of agglomeration. Using a systematic and multipronged approach for material characterization and employing critical biological endpoints, we determined the impact of the physicochemical properties of fullerenes on cellular interactions. We examined the ability of these fullerenes to regulate intracellular oxidative stress, necrosis and apoptosis in human monocytic THP1 cells. Results indicate that the carboxylate derivatization of fullerenes was the determining factor in their ability to induce apoptosis. In contrast, the dispersion characteristics of fullerenes were found to be more relevant when considering their redox function. We also established a significant role for functionalization-dependent fullerene-regulation of the caspase proteases in the elicited responses. In addition, there was a notable increase in the level of several anti-oxidant enzymes. Collectively, the results clearly indicate that the physicochemical properties of fullerenes significantly influence the elicited biological response, thus impacting future applications. This study is an initial effort to lay the groundwork for routine correlation and predictive analysis on engineered fullerenes, thus expediting their use.

  15. The energy spectrum and the optical absorption spectrum of C60 fullerene within the Hubbard model

    NASA Astrophysics Data System (ADS)

    Silant'ev, A. V.

    2015-10-01

    Anticommutator Green's functions and the energy spectrum of C60 fullerene are calculated in the approximation of static fluctuations within the Hubbard model. On the basis of this spectrum, an interpretation is proposed for the experimentally observed optical absorption bands of C60 fullerene. The parameters of C60 fullerene that characterize it within the Hubbard model are calculated by the optical absorption spectrum.

  16. Ni-Catalyzed direct 1,4-difunctionalization of [60]fullerene with benzyl bromides.

    PubMed

    Si, Weili; Zhang, Xuan; Asao, Naoki; Yamamoto, Yoshinori; Jin, Tienan

    2015-04-14

    A new Ni-catalyzed direct 1,4-difunctionalization of [60]fullerene with various benzyl bromides has been developed. The use of a DMSO additive combined with a nickel catalyst is indispensable for the formation of 1,4-dibenzyl fullerenes with a variety of functional groups. The reaction proceeds through the formation of a fullerene monoradical species. PMID:25765232

  17. Efficient resistive memory effect on SrTiO3 by ionic-bombardment

    NASA Astrophysics Data System (ADS)

    Gross, Heiko; Oh, Seongshik

    2011-08-01

    We show that ionic-bombardment leads to noticeable resistive memory effect on pure SrTiO3 (STO). In an Ar-bombarded STO crystal, two orders of resistance difference was observed between the high and low resistive states. We found that Ar-bombardment is more efficient than thermal-reduction in creating memory-effective oxygen vacancies. One of the advantages of the ionic-bombardment scheme is that it can be easily combined with lithographic processes to create spatially selective memory effect.

  18. Study of a hydrogen-bombardment process for molecular cross-linking within thin films

    SciTech Connect

    Liu, Y.; Yang, J.; Yang, D. Q.; Nie, H.-Y.; Lau, W. M.

    2011-02-21

    A low-energy hydrogen bombardment method, without using any chemical additives, has been designed for fine tuning both physical and chemical properties of molecular thin films through selectively cleaving C-H bonds and keeping other bonds intact. In the hydrogen bombardment process, carbon radicals are generated during collisions between C-H bonds and hydrogen molecules carrying {approx}10 eV kinetic energy. These carbon radicals induce cross-linking of neighboring molecular chains. In this work, we focus on the effect of hydrogen bombardment on dotriacontane (C{sub 32}H{sub 66}) thin films as growing on native SiO{sub 2} surfaces. After the hydrogen bombardment, XPS results indirectly explain that cross-linking has occurred among C{sub 32}H{sub 66} molecules, where the major chemical elements have been preserved even though the bombarded thin film is washed by organic solution such as hexane. AFM results show the height of the perpendicular phase in the thin film decreases due to the bombardment. Intriguingly, Young's modulus of the bombarded thin films can be increased up to {approx}6.5 GPa, about five times of elasticity of the virgin films. The surface roughness of the thin films can be kept as smooth as the virgin film surface after thorough bombardment. Therefore, the hydrogen bombardment method shows a great potential in the modification of morphological, mechanical, and tribological properties of organic thin films for a broad range of applications, especially in an aggressive environment.

  19. Surface wet-ability modification of thin PECVD silicon nitride layers by 40 keV argon ion treatments

    NASA Astrophysics Data System (ADS)

    Caridi, F.; Picciotto, A.; Vanzetti, L.; Iacob, E.; Scolaro, C.

    2015-10-01

    Measurements of wet-ability of liquid drops have been performed on a 30 nm silicon nitride (Si3N4) film deposited by a PECVD reactor on a silicon wafer and implanted by 40 keV argon ions at different doses. Surface treatments by using Ar ion beams have been employed to modify the wet-ability. The chemical composition of the first Si3N4 monolayer was investigated by means of X-ray Photoelectron Spectroscopy (XPS). The surface morphology was tested by Atomic Force Microscopy (AFM). Results put in evidence the best implantation conditions for silicon nitride to increase or to reduce the wet-ability of the biological liquid. This permits to improve the biocompatibility and functionality of Si3N4. In particular experimental results show that argon ion bombardment increases the contact angle, enhances the oxygen content and increases the surface roughness.

  20. Synthesis and Optical Properties of Fullerenes and Fullerene-Based Materials

    NASA Astrophysics Data System (ADS)

    Wang, Kai-An.

    This dissertation presents the original results of a systematic study on solid C_{60 }, C_{70} and materials based on these two species. We begin with a brief survey in Chapter 1 of the highlights of fullerene research results and an outline of the topics covered by this dissertation. This includes a discussion on the photo-assisted polymerization of C _{60} molecules that was discovered by our group. In Chapter 2, we describe the synthesis techniques which we have used to prepare the samples of fullerenes and fullerene-based materials. Graphite electrodes were used in an arc machine to generate fullerene -rich soot. Chapter 3 explains the experimental techniques involved in this thesis, including Raman, FTIR and UV-Visible spectroscopy. Presented in Chapter 4 are results of in-depth studies of the vibrational mode frequencies from the Raman and IR spectra of solid C_{60} thin films. These data are in excellent agreement with molecular vibration theory for an isolated C _{60} molecule, indicating that solid C_{60} is a molecular solid bound by van der Waals force. We have explored in great detail the (first- and second-order) vibrational modes of solid C_{60}. About 200 total IR and Raman spectral lines were found in our experiment for pristine solid C_{60 }. We have also analyzed these data to obtain the experimental values for all the vibrational mode frequencies of C_{60} with high accuracy that would be otherwise unaffordable by neutron scattering experiment. The first half of Chapter 5 demonstrates that the Raman spectra of alkali-metal-doped C_ {60} are independent of the mass, radius or electronic configuration of the alkali metal dopants. Furthermore, charge transfer from the alkali metals to the C _{60} molecules is found to be responsible for the (tangential) mode softening and (radial) mode stiffening in the Raman spectra. The second half of Chapter 5 is an exclusive low-temperature Raman spectroscopic study on the first homogeneous thin film samples M _3{rm C}_{60} (M = K, Rb) that were superconducting at 19 K (M = K) and 28 K (M = Rb), respectively. In Chapter 6 we discuss the vibrational and electronic absorption spectroscopic studies of the photo-assisted diffusion of oxygen into solid C_{60 }. Finally in Chapter 7, we present the results of our investigation into solid C_{70 } and M_{rm x} {rm C}_{70} materials, and compare these results with those obtained in solid C_{60} and M_ {rm x}{rm C}_{60 }. The alkali-metal-doping induced mode softening and stiffening in C_{70} are similar to those we found in C_{60 }. (Abstract shortened by UMI.).

  1. Ion-bombardment of nickel (110) at elevated temperature

    NASA Astrophysics Data System (ADS)

    Peddinti, Vijay Kumar

    The goal of this thesis is to study the behavior of ion-induced defects at the Y point on the Ni (110) surface at elevated temperatures. The electronic structure of the surface is examined using inverse photoemission spectroscopy (IPES), and the geometric structure is observed using low energy electron diffraction (LEED). These measurements lead to a better understanding of the surface properties. The clean Ni (110) surface exhibits a peak 2.6 eV above the Fermi level, indicating an unoccupied surface state near the Y point of the surface Brillouin zone (SBZ). Defects are induced by low energy ion bombardment at various temperatures, which result in a decrease of the peak intensity. The surface state eventually disappears when bombarded for longer times. We also observed that the surface heals faster when the crystal is being simultaneously sputtered and annealed at higher versus lower temperature. Finally the data for annealing while sputtering versus annealing after sputtering does not seem to exhibit much difference.

  2. Surface oxidation of metals by oxygen ion bombardment

    NASA Astrophysics Data System (ADS)

    Alov, Nikolai V.

    2007-03-01

    Surface oxidation of molybdenum, tungsten, niobium and tantalum by low-energy oxygen ion beams is investigated using X-ray photoelectron spectroscopy (XPS). Oxygen ion bombardment of molybdenum and tungsten surfaces leads to the formation of thin oxide films containing metals in oxidation states 4+, 5+ and 6+. At the initial stage of irradiation, rapid surface oxidation of molybdenum and tungsten was observed. At higher fluences the oxidation reaches saturation and the surface composition remains almost unchanged with increasing fluence. Oxygen ion bombardment of niobium and tantalum surfaces leads to the formation of thin oxide films containing niobium and tantalum in oxidation states 2+, 4+ and 5+. At the initial stage of irradiation, again rapid surface oxidation of niobium and tantalum was observed. At higher fluences the population of Nb2+ and Nb4+, Ta2+ and Ta4+ reaches a maximum and then begins to decrease. The population of Nb5+ and Ta5+ continues to increase and finally the entire oxide films consists of only Nb5+ and Ta5+, respectively.

  3. ETFE polymer bombarded with 1 MeV proton

    NASA Astrophysics Data System (ADS)

    Parada, M. A.; de Almeida, A.; Muntele, I.; Muntele, C.; Delalez, N.; Ila, D.

    2005-12-01

    The ethylenetetrafluoroethylene (ETFE) is a polymer formed by alternating ethylene and tetrafluoroethylene segments. It has high impact resistance and useful mechanical properties. ETFE can be used as components of pumps, valves, tie wraps, and electrical components. It can also be applied in the field of medical physics as intra venous catheters and as radiation dosimeter. When a material is exposed to the ionizing radiation, it suffers damage that depends on the type, energy and intensity of the radiation. In order to determine the radiation damage mechanism, ETFE films were bombarded with 1 MeV protons to the fluence between 1 1011 and 1 1016 protons/cm2 and the chemical species emitted during the bombardment were measured with residual gas analysis (RGA) and show that HF gas is the entity preferentially emitted. Optical absorption photospectrometry (OAP) and attenuated total reflectometry fourier transform infrared (ATR-FTIR) shows quantitative chemical evidence of the damage. Our results show that damage is detectable at low proton fluence, but damage that can compromise the application in dosimetry occurs only for fluence greater than 1014 protons/cm2.

  4. New concepts and applications in the macromolecular chemistry of fullerenes.

    PubMed

    Giacalone, Francesco; Martn, Nazario

    2010-10-01

    A new classification on the different types of fullerene-containing polymers is presented according to their different properties and applications they exhibit in a variety of fields. Because of their interest and novelty, water-soluble and biodegradable C(60)-polymers are discussed first, followed by polyfullerene-based membranes where unprecedented supramolecular structures are presented. Next are compounds that involve hybrid materials formed from fullerenes and other components such as silica, DNA, and carbon nanotubes (CNTs) where the most recent advances have been achieved. A most relevant topic is still that of C(60)-based donor-acceptor (D-A) polymers. Since their application in photovoltaics D-A polymers are among the most realistic applications of fullerenes in the so-called molecular electronics. The most relevant aspects in these covalently connected fullerene/polymer hybrids as well as new concepts to improve energy conversion efficiencies are presented.The last topics disccused relate to supramolecular aspects that are in involved in C(60)-polymer systems and in the self-assembly of C(60)-macromolecular structures, which open a new scenario for organizing, by means of non-covalent interactions, new supramolecular structures at the nano- and micrometric scale, in which the combination of the hydrofobicity of fullerenes with the versatility of the noncovalent chemistry afford new and spectacular superstructures. PMID:20799291

  5. C60 fullerene derivatized nanoparticles and their application to therapeutics.

    PubMed

    Lin, Chun-Mao; Lu, Tan-Yi

    2012-06-01

    Fullerenes can be formed into many new materials and devices. They have a wide range of applications in medicine, electronics, biomaterials, and energy production. An overview of the nanostructure and the physical and chemical characteristics of fullerene-drug derivatives is given. The biological behavior of fullerene derivatives shows their potential to medical application fields because C(60) is rapidly absorbed by tissues and is excreted through urinary tract and enterons, which reveals low toxicity in vitro and in vivo studies. Nanomedicine has become one of the most promising areas of nanotechnology, while many have claimed its therapeutic use against cancer, human immunodeficiency virus (HIV), and neurodegenerative disorders. Water-soluble C(60) fullerene derivatives that come from chemical modification largely enhance the biological efficacy. The blood-brain barrier (BBB) is a physical barrier composed of endothelial tight junctions that restrict the paracellular permeability. A major challenge facing neuropharmacology is to find compounds that can be delivered into the brain through the bloodstream. Fullerene C(60) was demonstratively able to cross the BBB by hybridizing a biologically active moiety dyad, which provides a promising clue as a pharmacological therapy of neural disorders. PMID:22455733

  6. Using surface plasmonics to turn on fullerene's dark excitons

    NASA Astrophysics Data System (ADS)

    Despoja, V.; Mowbray, D. J.

    2014-05-01

    Using our recently proposed Bethe-Salpeter G0W0 formulation, we explore the optical absorption spectra of fullerene (C60) near coinage metal surfaces (Cu, Ag, and Au). We pay special attention to how the surface plasmon ?S influences the optical activity of fullerene. We find that the lower-energy fullerene excitons at 3.77 and 4.8 eV only weakly interact with the surface plasmon. However, we find that the surface plasmon strongly interacts with the most intense fullerene ? exciton, i.e., the dipolar mode at ?? +?6.5 eV, and the quadrupolar mode at ?? -?6.8 eV. When fullerene is close to a copper surface (z0?5.3 ), the dipolar mode ?+ and "localized" surface plasmons in the molecule/surface interface hybridize to form two coupled modes which both absorb light. As a result, the molecule gains an additional optically active mode. Moreover, in resonance, when ?S??, the strong interaction with the surface plasmon destroys the ?- quadrupolar character and it becomes an optically active mode. In this case, the molecule gains two additional very intense optically active modes. Further, we find that this resonance condition, ?S??, is satisfied by silver and gold metal surfaces.

  7. Structures and electronic properties of fullerene-related compounds

    SciTech Connect

    Hettich, R.L.; Ying, Z.C.; Compton, R.N.

    1995-12-31

    The synthesis and characterization of fullerene-related compounds has been the subject of active research both experimentally and theoretically since the discovery of C{sub 60}. For example, endohedral fullerenes M@C{sub n} (carbon clusters containing a {open_quotes}trapped{close_quotes} atom M within their cage) can be generated for several different early transition metals and noble gases. The properties of these species have been modelled theoretically, and indicate that these species may have unusual applications. Likewise, the covalent attachment of hydrocarbon functional groups to a fullerene also alters its properties, opening up new applications as well. The focus of this presentation is to describe how Fourier transform ion cyclotron resonance (FTICR) can be used not only for the detection and identification of fullerene-related compounds, but also the detailed structural interrogation of their properties. In particular, laser desorption FTICR was used to examine endohedral La@C{sub n} species and {gamma}-radiolysis fullerene products. Collisional dissociation and charge transfer processes were used to probe the structures and electronic properties of these nanoclusters in detail.

  8. ON THE EXCITATION AND FORMATION OF CIRCUMSTELLAR FULLERENES

    SciTech Connect

    Bernard-Salas, J.; Jones, A. P.; Groenewegen, M. A. T.

    2012-09-20

    We compare and analyze the Spitzer mid-infrared spectrum of three fullerene-rich planetary nebulae in the Milky Way and the Magellanic Clouds: Tc1, SMP SMC 16, and SMP LMC 56. The three planetary nebulae share many spectroscopic similarities. The strongest circumstellar emission bands correspond to the infrared active vibrational modes of the fullerene species C{sub 60} and little or no emission is present from polycyclic aromatic hydrocarbons. The strengths of the fullerene bands in the three planetary nebulae are very similar, while the ratios of the [Ne III]15.5 {mu}m/[Ne II]12.8 {mu}m fine structure lines, an indicator of the strength of the radiation field, are markedly different. This raises questions about their excitation mechanism and we compare the fullerene emission to fluorescent and thermal models. In addition, the spectra show other interesting and common features, most notably in the 6-9 {mu}m region, where a broad plateau with substructure dominates the emission. These features have previously been associated with mixtures of aromatic/aliphatic hydrocarbon solids. We hypothesize on the origin of this band, which is likely related to the fullerene formation mechanism, and compare it with modeled hydrogenated amorphous carbon that present emission in this region.

  9. [sup 3]He NMR study looks at fullerene aromaticity

    SciTech Connect

    Baum, R.

    1994-02-28

    Is C[sub 60] aromatic What seems like a simple question has had a number of answers since the discovery of C[sub 60] and other fullerenes in 1985. Now, an ingenious set of experiments using endohedral C[sub 60] and C[sub 70] species with helium-3 atoms trapped inside the fullerene cages is providing new information about the aromatic nature of the fullerenes. The experiments showed that helium-3 nuclei encapsulated in C[sub 60] and C[sub 70] are shielded by 6 ppm and 29 ppm, respectively, relative to free [sup 3]He. These shieldings are unexpectedly large, indicating significant diamagnetic ring currents in C[sub 60] and very large ones in C[sub 70]. As far as C[sub 60]'s aromaticity is concerned, many traditional measures of aromaticity cannot easily be applied to the fullerenes. Ring currents are a diagnostic tool to detect aromaticity. With the fullerenes, they are about the only tool one has. The ring currents detected suggest that these compounds are aromatic.

  10. Fullerene exposures with oysters: embryonic, adult, and cellular responses.

    PubMed

    Ringwood, Amy H; Levi-Polyachenko, Nicole; Carroll, David L

    2009-09-15

    Oysters are an ecologically important group of filter-feeders, and a valuable toxicology model for characterizing the potential impacts of nanoparticles to marine organisms. Fullerene (C60) exposure studies with oysters, Crassostrea virginica, were conducted with a variety of biological levels, e.g., developmental studies with embryos, whole organism exposures with adults, and isolated hepatopancreas cells. Significant effects on embryonic development and lysosomal destabilization were observed at concentrations as low as 10 ppb. Moreover, based on our extensive experience with the lysosomal assay, the lysosomal destabilization rates at fullerene concentrations > or = 100 ppb were regarded as biologically significant as they are associated with reproductive failure. Interestingly, there was no significant increase in lipid peroxidation levels in hepatopancreas tissues. Oyster hepatopancreas tissues are composed of lysosomal rich cells, and confocal microscopy studies indicated thatthe fullerene particles readily accumulated inside hepatopancreas cells within 4 h. Fullerene aggregates tended to be localized and concentrated into lysosomes. The microscopic work in conjunction with the lysosomal function assays supports the premise that endocytotic and lysosomal pathways may be major targets of fullerenes and other nanoparticles. Nanoparticles that affect normal lysosomal and autophagic processes may contribute to long-term, chronic problems for individual health as well as ecosystem health. PMID:19806754

  11. Fullerene-rare gas mixed plasmas in an electron cyclotron resonance ion source

    SciTech Connect

    Asaji, T. Ohba, T.; Uchida, T.; Yoshida, Y.; Minezaki, H.; Ishihara, S.; Racz, R.; Biri, S.; Kato, Y.

    2014-02-15

    A synthesis technology of endohedral fullerenes such as Fe@C{sub 60} has developed with an electron cyclotron resonance (ECR) ion source. The production of N@C{sub 60} was reported. However, the yield was quite low, since most fullerene molecules were broken in the ECR plasma. We have adopted gas-mixing techniques in order to cool the plasma and then reduce fullerene dissociation. Mass spectra of ion beams extracted from fullerene-He, Ar or Xe mixed plasmas were observed with a Faraday cup. From the results, the He gas mixing technique is effective against fullerene destruction.

  12. Synthesis and chemical reactivity of tetrahydro[60]fullerene epoxides with both amino and aryl addends.

    PubMed

    Liang, Sisi; Xu, Liang; Gan, Liangbing

    2015-04-17

    Tetrahydro[60]fullerene epoxides C60(O)Ar(n)(NR2)(4-n), n = 1, 2, have been prepared by treating 1,4-adducts C60(OH)Ph and C60(Tol)2 with cyclic secondary amines. The epoxy moieties in these mixed tetrahydro[60]fullerene epoxides were hydrolyzed into the corresponding diol derivatives, which were further oxidized into diketone open-cage fullerenes with a 10-membered orifice. A few other reactions also showed that the present tetrahydro[60]fullerene epoxides with both amino and aryl addends exhibit improved chemical reactivity over the tetraamino[60]fullerene epoxide without any aryl group. PMID:25781177

  13. Quantitative UV Spectrophotometric Analysis of Mixtures of Substituted C60 Fullerenes

    NASA Astrophysics Data System (ADS)

    Kuznetsov, S. I.; Yunusova, D. S.; Yumagulova, R. Kh.; Miftakhov, M. S.; Kolesov, S. V.; Spivak, S. I.; Kantor, O. G.

    2015-09-01

    We propose a method for quantitative processing of experimental UV spectrometry data for mixtures of substituted fullerenes, taking into account measurement uncertainties. The experimental data can be represented as a system of Bouguer-Lambert linear equations, including the extinction coefficients for individual substituted fullerenes and the optical densities at wavelengths of the selected absorption maxima for each substituted fullerene. In order to take into account experimental uncertainties, we propose reducing this system of linear algebraic equations to a linear programming problem. Our algorithm allows us to quantitatively determine the fullerene content and the content of substituted fullerene derivatives in the total mixture with uncertainty ?20%.

  14. Liposome Formulation of Fullerene-Based Molecular Diagnostic and Therapeutic Agents

    PubMed Central

    Zhou, Zhiguo

    2013-01-01

    Fullerene medicine is a new but rapidly growing research subject. Fullerene has a number of desired structural, physical and chemical properties to be adapted for biological use including antioxidants, anti-aging, anti-inflammation, photodynamic therapy, drug delivery, and magnetic resonance imaging contrast agents. Chemical functionalization of fullerenes has led to several interesting compounds with very promising preclinical efficacy, pharmacokinetic and safety data. However, there is no clinical evaluation or human use except in fullerene-based cosmetic products for human skincare. This article summarizes recent advances in liposome formulation of fullerenes for the use in therapeutics and molecular imaging. PMID:24300561

  15. Tuning the properties of polymer bulk heterojunction solar cells by adjusting fullerene size to control intercalation

    SciTech Connect

    Cates, N.C.

    2010-02-24

    We demonstrate that intercalation of fullerene derivatives between the side chains of conjugated polymers can be controlled by adjusting the fullerene size and compare the properties of intercalated and nonintercalated poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (pBTTT):fullerene blends. The intercalated blends, which exhibit optimal solar-cell performance at 1:4 polymer:fullerene by weight, have better photoluminescence quenching and lower absorption than the nonintercalated blends, which optimize at 1:1. Understanding how intercalation affects performance will enable more effective design of polymer:fullerene solar cells.

  16. Comparative process analysis of fullerene production by the arc and the radio-frequency discharge methods.

    PubMed

    Markovi?, Z; Todorovi?-Markovi?, B; Mohai, I; Farkas, Z; Kovats, E; Szepvolgyi, J; Otasevi?, D; Scheier, P; Feil, S; Romcevi?, N

    2007-01-01

    In this work, comparative analysis of processes in carbon arc and radio frequency (RF) plasma during fullerene synthesis has been presented. The kinetic model of fullerene formation developed earlier has been verified in both types of plasma reactors. The fullerene yield depended on carbon concentration, velocity of plasma flame and rotational temperature of C2 radicals predominantly. When mean rotational temperature of C2 radicals was 3000 K, the fullerene yield was the highest regardless of the type of used reactor. The zone of fullerene formation is larger significantly in RF plasma reactor compared to arc reactor. PMID:17450899

  17. Atom penetration from a thin film into the substrate during sputtering by polyenergetic Ar{sup +} ion beam with mean energy of 9.4 keV

    SciTech Connect

    Kalin, B.A.; Gladkov, V.P.; Volkov, N.V.; Sabo, S.E.

    1995-12-31

    Penetration of alien atoms (Be, Ni) into Be, Al, Zr, Si and diamond was investigated under Ar{sup +} ion bombardment of samples having thermally evaporated films of 30--50 nm. Sputtering was carried out using a wide energy spectrum beam of Ar{sup +} ions of 9.4 keV to dose D = 1 {times} 10{sup 16}--10{sup 19} ion/cm{sup 2}. Implanted atom distribution in the targets was measured by Rutherford backscattering spectrometry (RBS) of H{sup +} and He{sup +} ions with energy of 1.6 MeV as well as secondary ion mass-spectrometry (SIMS). During the bombardment, the penetration depth of Ar atoms increases with dose linearly. This depth is more than 3--20 times deeper than the projected range of bombarding ions and recoil atoms. This is a deep action effect. The analysis shows that the experimental data for foreign atoms penetration depth are similar to the data calculated for atom migration through the interstitial site in a field of internal (lateral) compressive stresses created in the near-surface layer of the substrate as a result of implantation. Under these experimental conditions atom ratio r{sub i}/r{sub m} (r{sub i} -- radius of dopant, r{sub m} -- radius target of substrate) can play a principal determining role.

  18. Exploration in metallic nitride fullerenes and oxometallic fullerenes: A new class of metallofullerenes

    NASA Astrophysics Data System (ADS)

    Mackey, Mary Alice

    2011-07-01

    Research groups around the world have taken an interest in the synthesis, purification, characterization, and functionalization of Metallic Nitride Fullerenes (MNFs) since their discovery in 1999. This dissertation details the discovery of another new class of molecules---Oxometallic Fullerenes (OMFs). There are many groups worldwide doing research on MNFs, and there is a large database of published MNF research, but we have had a unique opportunity to fill a research void on OMFs as at present no one else is doing research on these molecules; herein we take molecules that we discover and perform seminal research relating to them. MNF research is closely tied to this project; MNFs are a stepping stone because of their greater abundance and similar reactivity. Building off of previously developed techniques, we are able to create new methods for the separation and isolation of MNFs and OMFs. We studied the reactivity differences of various MNFs and OMFs in order to utilize Lewis acid chemistry as a tool for the enrichment and purification of both MNFs and OMFs, eventually resulting in a detailed separations technique. We have also begun studies to functionalize the carbon cage of endohedral metallofullerenes---this research includes using Lewis acids and various aromatic solvents via Friedel-Crafts reactions.

  19. Toxicity of polyhydroxylated fullerene to mitochondria.

    PubMed

    Yang, Li-Yun; Gao, Jia-Ling; Gao, Tian; Dong, Ping; Ma, Long; Jiang, Feng-Lei; Liu, Yi

    2016-01-15

    Mitochondrial dysfunction is considered as a crucial mechanism of nanomaterial toxicity. Herein, we investigated the effects of polyhydroxylated fullerene (C60(OH)44, fullerenol), a model carbon-based nanomaterial with high water solubility, on isolated mitochondria. Our study demonstrated that fullerenol enhanced the permeabilization of mitochondrial inner membrane to H(+) and K(+) and induced mitochondrial permeability transition (MPT). The fullerenol-induced swelling was dose-dependent and could be effectively inhibited by MPT inhibitors such as cyclosporin A (CsA), adenosine diphosphate (ADP), ruthenium red (RR) and ethylenediaminetetraacetic acid (EDTA). After treating the mitochondria with fullerenol, the mitochondrial membrane potential (MMP) was found collapsed in a concentration-independent manner. The fluorescence anisotropy of hematoporphyrin (HP) changed significantly with the addition of fullerenol, while that of 1,6-diphenyl-hexatriene (DPH) changed slightly. Moreover, a decrease of respiration state 3 and increase of respiration state 4 were observed when mitochondria were energized with complex II substrate succinate. The results of transmission electron microscopy (TEM) provided direct evidence that fullerenol damaged the mitochondrial ultrastructure. The investigations can provide comprehensive information to elucidate the possible toxic mechanism of fullerenols at subcellular level. PMID:26348144

  20. B14: An all-boron fullerene

    NASA Astrophysics Data System (ADS)

    Cheng, Longjiu

    2012-03-01

    Experiments revealed that small boron cluster anions and cations are (quasi-)planar. For neutral boron cluster, (quasi-)planar motifs are also suggested to be global minimum by many theoretical studies, and a structural transformation from quasi-planar to double-ring tubular structures occurs at B20. However, a missing opportunity is found for neutral B14, which is a flat cage and more stable than the previous quasi-planar one by high level ab initio calculations. The B14 cage has a large HOMO-LUMO gap (2.69 eV), and NICS values reveal that it is even more aromatic than the known most aromatic quasi-planar B12 and double-ring B20, which indicates a close-shell electronic structure. Chemical bonding analysis given by AdNDP reveals that the B14 cage is an all-boron fullerene with 18 delocalized ?-electrons following the 2(n+1)2 rule of spherical aromaticity. The geometry and bonding features of the B14 cage are unique denying conversional thinking.

  1. THE FORMATION OF COSMIC FULLERENES FROM AROPHATIC CLUSTERS

    SciTech Connect

    Micelotta, Elisabetta R.; Cami, Jan; Peeters, Els; Fanchini, Giovanni; Jones, Anthony P.; Bernard-Salas, Jeronimo

    2012-12-10

    Fullerenes have recently been identified in space and they may play a significant role in the gas and dust budget of various astrophysical objects including planetary nebulae (PNe), reflection nebulae, and H II regions. The tenuous nature of the gas in these environments precludes the formation of fullerene materials following known vaporization or combustion synthesis routes even on astronomical timescales. We have studied the processing of hydrogenated amorphous carbon (a-C:H or HAC) nanoparticles and their specific derivative structures, which we name ''arophatics'', in the circumstellar environments of young, carbon-rich PNe. We find that UV-irradiation of such particles can result in the formation of fullerenes, consistent with the known physical conditions in PNe and with available timescales.

  2. Antioxidant Properties of Water-Soluble Fullerene Derivatives

    NASA Astrophysics Data System (ADS)

    Beuerle, Florian; Lebovitz, Russell; Hirsch, Andreas

    Due to their inherent electronic properties, fullerenes are considered as radical sponges being capable of effectively quenching reactive oxygen species (ROS). The most promising candidates for potential pharmaceutical applications are therefore water-soluble fullerene derivatives, since they provide reasonable biological availability. In light of these considerations, we give an overview over the most recent concepts for designing and synthesizing real water-soluble fullerene compounds. Several studies concerning the quenching activities against ROS-like Superoxide radical anion of some of these novel compounds are reviewed. We finally present first promising investigations about cytoprotective and neuroprotective activities of several carboxyfullerenes in zebrafish embroys as a mammalian model system. By comparing the activities for different addition patterns and other structural changes some first conclusions concerning a structure-function relationship can be drawn.

  3. Casimir-Polder interaction of fullerene molecules with surfaces

    NASA Astrophysics Data System (ADS)

    Buhmann, Stefan Yoshi; Scheel, Stefan; Ellingsen, Simen .; Hornberger, Klaus; Jacob, Andreas

    2012-04-01

    We calculate the thermal Casimir-Polder potential of C60 and C70 fullerene molecules near gold and silicon nitride surfaces, motivated by their relevance for molecular matter-wave interference experiments. We obtain the coefficients governing the asymptotic power laws of the interaction in the thermal, retarded, and nonretarded distance regimes and evaluate the full potential numerically. The interaction is found to be dominated by electronic transitions and hence independent of the internal temperature of the molecules. The contributions from phonon transitions, which are affected by the molecular temperature, give rise to only a small correction. Moreover, we find that the sizable molecular line widths of thermal fullerenes may modify the nonretarded interaction, depending on the model used. Detailed measurements of the nonretarded potential of fullerene thus allow one to distinguish between different theories of incorporating damping.

  4. Heterogeneities in fullerene nanoparticle aggregates affecting reactivity, bioactivity, and transport.

    PubMed

    Chae, So-Ryong; Badireddy, Appala R; Farner Budarz, Jeffrey; Lin, Shihong; Xiao, Yao; Therezien, Mathieu; Wiesner, Mark R

    2010-09-28

    Properties of nanomaterial suspensions are typically summarized by average values for the purposes of characterizing these materials and interpreting experimental results. We show in this work that the heterogeneity in aqueous suspensions of fullerene C(60) aggregates (nC(60)) must be taken into account for the purposes of predicting nanomaterial transport, exposure, and biological activity. The production of reactive oxygen species (ROS), microbial inactivation, and the mobility of the aggregates of the nC(60) in a silicate porous medium all increased as suspensions were fractionated to enrich with smaller aggregates by progressive membrane filtration. These size-dependent differences are attributed to an increasing degree of hydroxylation of nC(60) aggregates with decreasing size. As the quantity and influence of these more reactive fractions may increase with time, experiments evaluating fullerene transport and toxicity end points must take into account the evolution and heterogeneity of fullerene suspensions. PMID:20707347

  5. Helium-carbon arc plasma: Fullerene formation and spectroscopy

    SciTech Connect

    Huczko, A.; Lange, H.; Byszewski, P.

    1995-12-31

    The discovery of cage-like carbon molecules (C{sub 60}, C{sub 70}{hor_ellipsis}) by H. Kroto et al. in 1985 sparked the imagination worldwide and resulted in an explosion of research activities. The greatest open question is how such compact structures form so efficiently, It is known from an isotope-scrambling experiments that the fullerenes result from the condensation of carbon atoms in the hot carbon vapor. Several pathways have been suggested but while there is no direct experimental evidence against any of the proposed mechanism, there is not any strong evidence in their favor. Thus it seems reasonable to study the yield of fullerene formation with the simultaneous diagnostics of carbon plasma. Such an approach could give new insights into fullerene formation mechanistics.

  6. A search for diffuse bands in fullerene planetary nebulae: evidence of diffuse circumstellar bands

    NASA Astrophysics Data System (ADS)

    Díaz-Luis, J. J.; García-Hernández, D. A.; Kameswara Rao, N.; Manchado, A.; Cataldo, F.

    2015-01-01

    Large fullerenes and fullerene-based molecules have been proposed as carriers of diffuse interstellar bands (DIBs). The recent detection of the most common fullerenes (C60 and C70) around some planetary nebulae (PNe) now enable us to study the DIBs towards fullerene-rich space environments. We search DIBs in the optical spectra towards three fullerene-containing PNe (Tc 1, M 1-20, and IC 418). Special attention is given to DIBs which are found to be unusually intense towards these fullerene sources. In particular, an unusually strong 4428 Å absorption feature is a common charateristic of fullerene PNe. Similar to Tc 1, the strongest optical bands of neutral C60 are not detected towards IC 418. Our high-quality (S/N > 300) spectra for PN Tc 1, together with its large radial velocity, permit us to search for the presence of diffuse bands of circumstellar origin, which we refer to as diffuse circumstellar bands (DCBs). We report the first tentative detection of two DCBs at 4428 and 5780 Å in the fullerene-rich circumstellar environment around the PN Tc 1. Laboratory and theoretical studies of fullerenes in their multifarious manifestations (carbon onions, fullerene clusters, or even complex species formed by fullerenes and other molecules like PAHs or metals) may help solve the mystery of some of the diffuse band carriers. Appendix A is available in electronic form at http://www.aanda.org

  7. Relief evolution of HOPG under high-fluence 30 keV argon ion irradiation

    NASA Astrophysics Data System (ADS)

    Andrianova, N. N.; Borisov, A. M.; Mashkova, E. S.; Shemukhin, A. A.; Shulga, V. I.; Virgiliev, Yu. S.

    2015-07-01

    The results of the experimental study of sputtering and erosion of the basal plane of HOPG under irradiation with 30-keV Ar+ in the range from RT to 400 °C are presented. It has been found that developed at elevated (⩾250 °C) temperatures needle-like microscopic relief results in twofold sputtering yield increase (Y ≈ 2) in comparison with sputtering of a surface with an etch pits microscopic relief at the temperatures less than the ion-induced texture transition temperature Tt ≈ 150 °C. The effects of ion-induced graphite relief on high-dose sputtering have been studied using binary-collision computer simulation. The relief was modeled as a sine function surface along two mutually perpendicular surface axes. The simulation has shown that at some parameters of the relief the essential part of the bombarding ions undergoes inclined incidence on the walls of surface hillocks, which increases the density of ion-atom collisions near the surface and, correspondingly, the ejection of atoms. This effect leads to non-monotonic behavior of the sputtering yield on the relief aspect ratio (amplitude/period). The sputtering yield decreases upon reaching the maximum at aspect ratio of 4, and becomes lower than that for a flat surface. The simulation permits to estimate the relation of amplitude to period of relief at T < Tt.

  8. Theory of the Miscibility of Fullerenes in Random Copolymer Melts

    SciTech Connect

    Dadmun, Mark D; Sumpter, Bobby G; Schweizer, Kenneth; Banerjee, Debapriya

    2013-01-01

    We combine polymer integral equation theory and computational chemistry methods to study the interfacial structure, effective interactions, miscibility and spatial dispersion mechanism of fullerenes dissolved in specific random AB copolymer melts characterized by strong non-covalent electron donor-acceptor interactions with the nanofiller. A statistical mechanical basis is developed for designing random copolymers to optimize fullerene dispersion at intermediate copolymer compositions. Pair correlation calculations reveal a strong sensitivity of interfacial packing near the fullerene to copolymer composition and adsorption energy mismatch. The potential of mean force between fullerenes displays rich trends, often non-monotonic with copolymer composition, reflecting a non-additive competition between direct filler attractions and polymer-mediated bridging and steric stabilization. The spinodal phase diagrams are in qualitative agreement with recent solubility limit experimental observations on three systems, and testable predictions are made for other random copolymers. The distinctive non-monotonic variation of miscibility with copolymer composition is found to be primarily a consequence of composition-dependent, spatially short-range attractions between the A and B monomers with the fullerene. A remarkably rich, polymer-specific temperature dependence of the spinodal diagram is predicted which reflects the thermal sensitivity of spatial correlations which can result in fullerene miscibility either increasing or decreasing with cooling. The calculations are contrasted with a simpler effective homopolymer model and the random structure Flory-Huggins model. The former appears to be qualitatively reasonable but can incur large quantitative errors since it misses preferential packing of monomers near nanoparticles, while the latter appears to fail qualitatively due to its neglect of all spatial correlations.

  9. Single-fullerene manipulation inside a carbon nanotube

    NASA Astrophysics Data System (ADS)

    Glukhova, O. E.; Kirillova, I. V.; Saliy, I. N.; Slepchenkov, M. M.

    2011-03-01

    Here we are representing the results of the tight-binding molecular modeling of the process of the synthesis of the dimer (C28)2 and the retinoid-C60 linked molecules inside a carbon nanotube. The nanotube is located between two electrodes connected with a power source. The positively charged fullerene C60 moves from one end of the tube to the other. The motion of C60 is controlled by an external electric field. Moving fullerene C60 compresses the molecules located in one of the nanotube ends. The located molecules undergone axial compression moves toward each other. When the pressure created in the tube provides both the overlap of π-electrons of the C28 fullerenes and the covalent bonds formation, the intermediate phase of the (C28)2 dimer is synthesized: (C28)2 [6 + 6]. The pressure becomes equal to ~35 TPa. After returning the fullerene C60 to the initial state, the (C28)2 dimer is izomerized with the reorientation in the tube field. So, (C28)2 transfers to the stable phase (C28)2 [1+1]. If the moving fullerene C60 compresses the retinol-molecule then synthesis of retinoid-C60 linked molecules takes place. In conclusion, the dimer/polymer synthesis inside the carbon nanotube is real, the dimers and polymers are stable and may be synthesized in the field of the holding potential nanotube, and the fullerene polymerization in the nanotube guarantees the absence of any additives in the final product. The motion of the atoms is determined by the classical molecular modeling method where Newton's equations of motion are integrated with a third-order Nordsieck predictor corrector. Time steps of 0.15-0.25 fs were used in the simulations.

  10. Thermal, sonochemical, and mechanical behaviors of single crystal [60]fullerene nanotubes.

    PubMed

    Rauwerdink, Kristen; Liu, Jun-Fu; Kintigh, Jeremy; Miller, Glen P

    2007-06-01

    Although related to conventional carbon nanotubes in both shape and construction, fullerene nanowhiskers and fullerene nanotubes have received far less attention. A modified liquid-liquid interfacial precipitation technique is described to produce relatively uniform batches of [60]fullerene nanotubes in high yield. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) reveal that the tubes possess approximately 100-nm inside diameters and 300-nm outside diameters. The [60]fullerene nanotubes degrade slowly at 180 degrees C, eventually collapsing into micron scale [60]fullerene discs and rods, as revealed by optical microscopy and AFM. Ultrasonic cavitation chops [60]fullerene nanotubes into smaller segments within seconds. Longer ultrasonic bathing leads to considerable structural damage in which the sidewalls rupture. Mechanical stress tests using an AFM microscope tip effectively dent and break [60]fullerene nanowhiskers, revealing a hollow interior. PMID:17479988

  11. Evidence Supporting an Early as Well as Late Heavy Bombardment on the Moon

    NASA Technical Reports Server (NTRS)

    Frey, Herbert

    2015-01-01

    Evidence supporting an intense early bombardment on the Moon in addition to the traditional Late Heavy Bombardment at approx. 4 BY ago include the distribution of N(50) Crater Retention Ages (CRAs) for candidate basins, a variety of absolute age scenarios for both a "young" and an "old" Nectaris age, and the decreasing contrasts in both topographic relief and Bouguer gravity with increasing CRA.

  12. Fullerenes: A New Carrier Phase for Noble Gases in Meteorites

    NASA Technical Reports Server (NTRS)

    Becker, Luann

    2004-01-01

    The major focus of our research effort has been to measure the noble gases encapsulated within fullerenes, a new carbon carrier phase and compare it to the myriad of components found in the bulk meteorite acid residues. We have concentrated on the carbonaceous chondrites (Allende, Murchison and Tagish Lake) since they have abundant noble gases, typically with a planetary signature that dominates the stepped-release of the meteorite bulk acid residue. They also contain an extractable fullerene component that can be isolated and purified from the same bulk material.

  13. Effect on magnetic properties of germanium encapsulated C60 fullerene

    NASA Astrophysics Data System (ADS)

    Umran, Nibras Mossa; Kumar, Ranjan

    2013-02-01

    Structural and electronic properties of Gen(n = 1-4) doped C60 fullerene are investigated with ab initio density functional theory calculations by using an efficient computer code, known as SIESTA. The pseudopotentials are constructed using a Trouiller-Martins scheme, to describe the interaction of valence electrons with the atomic cores. In endohedral doped embedding of more germanium atoms complexes we have seen that complexes are stable and thereafter cage break down. We have also investigated that binding energy, electronic affinity increases and magnetic moment oscillating behavior as the number of semiconductor atoms in C60 fullerene goes on increasing.

  14. B38: an all-boron fullerene analogue

    NASA Astrophysics Data System (ADS)

    Lv, Jian; Wang, Yanchao; Zhu, Li; Ma, Yanming

    2014-09-01

    Fullerene-like structures formed by elements other than carbon have long been sought. Finding all-boron (B) fullerene-like structures is challenging due to the geometrical frustration arising from competitions among various structural motifs. We report here the prediction of a B38 fullerene analogue found through first-principles swarm structure searching calculations. The structure is highly symmetric and consists of 56 triangles and four hexagons, which provide an optimal void in the center of the cage. Energetically, it is more favorable than the planar and tubular structures, and possesses an unusually high chemical stability: a large energy gap (~2.25 eV) and a high double aromaticity, superior to those of most aromatic quasi-planar B12 and double-ring B20 clusters. Our findings represent a key step forward towards to the understanding of structures of medium-sized B clusters and map out the experimental direction of the synthesis of an all-B fullerene analogue.Fullerene-like structures formed by elements other than carbon have long been sought. Finding all-boron (B) fullerene-like structures is challenging due to the geometrical frustration arising from competitions among various structural motifs. We report here the prediction of a B38 fullerene analogue found through first-principles swarm structure searching calculations. The structure is highly symmetric and consists of 56 triangles and four hexagons, which provide an optimal void in the center of the cage. Energetically, it is more favorable than the planar and tubular structures, and possesses an unusually high chemical stability: a large energy gap (~2.25 eV) and a high double aromaticity, superior to those of most aromatic quasi-planar B12 and double-ring B20 clusters. Our findings represent a key step forward towards to the understanding of structures of medium-sized B clusters and map out the experimental direction of the synthesis of an all-B fullerene analogue. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01846j

  15. Graph-theoretic independence as a predictor of fullerene stability

    NASA Astrophysics Data System (ADS)

    Fajtlowicz, S.; Larson, C. E.

    2003-08-01

    The independence number of the graph of a fullerene, the size of the largest set of vertices such that no two are adjacent (corresponding to the largest set of atoms of the molecule, no pair of which are bonded), appears to be a useful selector in identifying stable fullerene isomers. The experimentally characterized isomers with 60, 70 and 76 atoms uniquely minimize this number among the classes of possible structures with, respectively, 60, 70 and 76 atoms. Other experimentally characterized isomers also rank extremely low with respect to this invariant. These findings were initiated by a conjecture of the computer program Graffiti.

  16. Molecular dynamical modelling of endohedral fullerenes formation in plasma

    NASA Astrophysics Data System (ADS)

    Fedorov, A. S.; Kovaleva, E. A.; Lubkova, T. A.; Popov, Z. I.; Kuzubov, A. A.; Visotin, M. A.; Irle, S.

    2016-02-01

    The initial stages of fullerene and endohedral metallofullerene (EMF) synthesis in carbon-helium plasma at 1500 K and 2500 K have been simulated with quantum chemical molecular dynamics (MD) based on density-functional tight-binding (DFTB). The cases of formation of large (>100 atoms) sp2-carbon clusters with scandium atoms inside were observed. These clusters are considered as precursors of fullerenes or EMFs, and thus it is shown that formation of EMFs can be explained within the framework of "shrinking hot giant" mechanism. Also, the dependence of formation rates on plasma parameters, including temperature, buffer gas and metal atoms concentrations, has been studied.

  17. Direct Delocalization for Calculating Electron Transfer in Fullerenes

    SciTech Connect

    Arntsen, Christopher D.; Reslan, Randa; Hernandez, Samuel; Gao, Yi; Neuhauser, Daniel

    2013-08-05

    A method is introduced for simple calculation of charge transfer between very large solvated organic dimers (fullerenes here) from isolated dimer calculations. The individual monomers in noncentrosymmetric dimers experience different chemical environments, so that the dimers do not necessarily represent bulk-like molecules. Therefore, we apply a delocalizing bias directly to the Fock matrix of the dimer system, and verify that this is almost as accurate as self-consistent solvation. As large molecules like fullerenes have a plethora of excited states, the initially excited state orbitals are thermally populated, so that the rate is obtained as a thermal average over Marcus thermal transfers.

  18. Horror vacui or topological in-out isomerism in perhydrogenated fullerenes: C60H60 and monoalkylated perhydrogenated fullerenes

    NASA Astrophysics Data System (ADS)

    Dodziuk, Helena; Nowinski, Krzysztof

    1996-02-01

    In endohedral chemistry, one of the exciting prospects offered by the cage-like structure of fullerenes, several aspects of the calculations on in-out isomerism of perhydrogenated fullerene and their consequences went unnoticed, e.g. the topological character of the isomerism, the instability of C 60F 60, which was thought to revolutionize industry as an ideal lubricant, as well as the possibility of in-out isomerism in alkylated fulleranes. Molecular mechanics calculations indicate that for smaller alkyl groups the 'in' isomer is significantly more stable extending the possibility of endohedral fullerene chemistry. C 60H 60 and its derivatives can be considered as examples of a manifestation of the ancient 'horror vacui' concept.

  19. Linear attenuation coefficients of tissues from 1 keV to 150 keV

    NASA Astrophysics Data System (ADS)

    Bke, Aysun

    2014-09-01

    The linear attenuation coefficients and three interaction processes have been computed for liver, kidney, muscle, fat and for a range of x-ray energies from 1 keV to 150 keV. Molecular photoelectric absorption cross sections were calculated from atomic cross section data. Total coherent (Rayleigh) and incoherent (Compton) scattering cross sections were obtained by numerical integration over combinations of F2m(x) with the Thomson formula and Sm(x) with the Klein-Nishina formula, respectively. For the coherent (Rayleigh) scattering cross section calculations, molecular form factors were obtained from recent experimental data in the literature for values of x<1 -1 and from the relativistic modified atomic form factors for values of x?1 -1. With the inclusion of molecular interference effects in the coherent (Rayleigh) scattering, more accurate knowledge of the scatter from these tissues will be provided. The number of elements involved in tissue composition is 5 for liver, 47 for kidney, 44 for muscle and 3 for fat. The results are compared with previously published experimental and theoretical linear attenuation coefficients. In general, good agreement is obtained. The molecular form factors and scattering functions and cross sections are incorporated into a Monte Carlo program. The energy distributions of x-ray photons scattered from tissues have been simulated and the results are presented.

  20. Bombarding Cancer: Biolistic Delivery of therapeutics using Porous Si Carriers

    NASA Astrophysics Data System (ADS)

    Zilony, Neta; Tzur-Balter, Adi; Segal, Ester; Shefi, Orit

    2013-08-01

    A new paradigm for an effective delivery of therapeutics into cancer cells is presented. Degradable porous silicon carriers, which are tailored to carry and release a model anti-cancer drug, are biolistically bombarded into in-vitro cancerous targets. We demonstrate the ability to launch these highly porous microparticles by a pneumatic capillary gene gun, which is conventionally used to deliver cargos by heavy metal carriers. By optimizing the gun parameters e.g., the accelerating gas pressure, we have successfully delivered the porous carriers, to reach deep targets and to cross a skin barrier in a highly spatial resolution. Our study reveals significant cytotoxicity towards the target human breast carcinoma cells following the delivery of drug-loaded carriers, while administrating empty particles results in no effect on cell viability. The unique combination of biolistics with the temporal control of payload release from porous carriers presents a powerful and non-conventional platform for designing new therapeutic strategies.

  1. Plasma properties in electron-bombardment ion thrusters

    NASA Technical Reports Server (NTRS)

    Matossian, J. N.; Beattie, J. R.

    1987-01-01

    The paper describes a technique for computing volume-averaged plasma properties within electron-bombardment ion thrusters, using spatially varying Langmuir-probe measurements. Average values of the electron densities are defined by integrating the spatially varying Maxwellian and primary electron densities over the ionization volume, and then dividing by the volume. Plasma properties obtained in the 30-cm-diameter J-series and ring-cusp thrusters are analyzed by the volume-averaging technique. The superior performance exhibited by the ring-cusp thruster is correlated with a higher average Maxwellian electron temperature. The ring-cusp thruster maintains the same fraction of primary electrons as does the J-series thruster, but at a much lower ion production cost. The volume-averaged predictions for both thrusters are compared with those of a detailed thruster performance model.

  2. Plasma properties in electron-bombardment ion thrusters

    SciTech Connect

    Matossian, J.N.; Beattie, J.R.

    1987-05-01

    The paper describes a technique for computing volume-averaged plasma properties within electron-bombardment ion thrusters, using spatially varying Langmuir-probe measurements. Average values of the electron densities are defined by integrating the spatially varying Maxwellian and primary electron densities over the ionization volume, and then dividing by the volume. Plasma properties obtained in the 30-cm-diameter J-series and ring-cusp thrusters are analyzed by the volume-averaging technique. The superior performance exhibited by the ring-cusp thruster is correlated with a higher average Maxwellian electron temperature. The ring-cusp thruster maintains the same fraction of primary electrons as does the J-series thruster, but at a much lower ion production cost. The volume-averaged predictions for both thrusters are compared with those of a detailed thruster performance model. 20 references.

  3. Uses of ion bombardment in thin-film deposition

    SciTech Connect

    Erck, R.A.; Fenske, G.R.; Erdemir, A.

    1990-10-01

    Use of plasma- and ion-beam-modified surfaces and surface coatings in continually expanding in engineering disciplines. The purpose of these modifications and treatments is to impart favorable properties, such as wear resistance and lubricity, to the surfaces, while at the same time retaining the strength or toughness of the bulk materials. Energetic-ion bombardment can be used to modify the structural and chemical properties of surfaces or applied coatings. Ion-implantation has been used for many years, and recently, other surface-modification techniques, among them ion-beam mixing and ion-beam-assisted deposition, have attracted attention because they permit application of highly adherent lubricious and wear-resistant films. In this paper, ion-beam techniques are described from the viewpoint of ion-surface interactions, and some avenues for the engineering of tribological surfaces are presented. 100 refs., 4 figs.

  4. Changes of Dust Grain Properties Under Particle Bombardment

    SciTech Connect

    Pavlu, J.; Richterova, I.; Safrankova, J.; Nemecek, Z.; Fujita, D.

    2008-09-07

    The dust in space environments is exposed to particle bombardment. Under an impact of ions, electrons, and photons, the charge of a particular grain changes and, in some cases, the grain structure can be modified. The present study deals with spherical melamine formaldehyde resin grains that are frequently used in many dusty plasmas and microgravity experiments and it concentrates on the influence of the electron beam impact on a grain size. We have performed series of experiments based on the SEM technique. Our investigation has shown that the electron impact can cause a significant increase of the grain size. We discuss changes of material properties and consequences for its applications in laboratory and space experiments.

  5. Cationization of organometallo carbonyl compounds by fast ion bombardment

    NASA Astrophysics Data System (ADS)

    Siuzdak, Gary; Wendeborn, Sebastian V.; Nicolaou, K. C.

    1992-01-01

    Organodicobalt, organochromium, and organomolybdenum carbonyl complexes have been studied using fast ion bombardment mass spectrometry. It has been found that the addition of cesium iodide to the liquid matrix, m-NBA, can significantly enhance the ability to observed the precursor ions of these organometallics through charge localization. In most cases the [M + Cs]+ ions were more abundant than the radical cations M-, the protonated molecules [M + H]+, or the sodium cationized molecules [M + Na]+ which were either unobservable or less intense than those treated with the cesium iodide salt solution. The decomposition of the compounds took place primarily through the successive loss of carbonyls from the radical cation with some carbonyl loss observed through the protonated and cationized species. The FAB matrix ions produced when cesium iodide was added to m-NBA also allowed for internal calibration.

  6. An 8-cm electron bombardment thruster for auxiliary propulsion

    NASA Technical Reports Server (NTRS)

    Hudson, W. R.; Banks, B. A.

    1973-01-01

    Thruster size, beam current level, and specific impulse trade-offs are considered for mercury electron bombardment ion thrusters to be used for north-south station keeping of geosynchronous spacecraft. An 8-cm diameter thruster operating at 2750 seconds specific impulse at thrust levels of 4.4 mN (1 m1b) to 8.9 mN (2 m6b) with a design life of 20,000 hours and 10,000 cycles is being developed. The thruster will have a dished two-grid system capable of thrust vectoring of + or - 10 degrees in two orthogonal directions. A preliminary thruster has been fabricated and tested; thruster performance characteristics have been determined at 4.45, 6.68, and 8.90 millinewtons.

  7. ATS-6 - Cesium bombardment engine north-south stationkeeping experiment

    NASA Technical Reports Server (NTRS)

    Worlock, R. M.; James, E. L.; Hunter, R. E.; Bartlett, R. O.

    1975-01-01

    Two 0.004 N thrust cesium bombardment ion thrustors have been developed and used for north-south stationkeeping in the geostationary Applications Technology Satellite-6 (ATS-6). The thrustor subsystems are mounted on the north and south faces of the earth viewing module such that 0.0026 N of thrust is applied normal to the orbit plane and 0.0036 N is applied radially upward. The change in the orbit inclination of the satellite is maintained at zero by operating the two thrustors alternately so that their thrust components, normal to the orbital plane, are symmetrically applied about the nodal crossings. Initial operation of the thrustors was successful. There was no interference with the satellite communications systems and the predicted spacecraft operating potential was verified. Subsequent trials failed due to a defect in the operation of the propellant reservoirs in zero g. A feed line valve is under development to correct this difficulty.

  8. Significant enhancement of negative secondary ion yields by cluster ion bombardment combined with cesium flooding.

    PubMed

    Philipp, Patrick; Angerer, Tina B; Smfors, Sanna; Blenkinsopp, Paul; Fletcher, John S; Wirtz, Tom

    2015-10-01

    In secondary ion mass spectrometry (SIMS), the beneficial effect of cesium implantation or flooding on the enhancement of negative secondary ion yields has been investigated in detail for various semiconductor and metal samples. All results have been obtained for monatomic ion bombardment. Recent progress in SIMS is based to a large extent on the development and use of cluster primary ions. In this work we show that the enhancement of negative secondary ions induced by the combination of ion bombardment with simultaneous cesium flooding is valid not only for monatomic ion bombardment but also for cluster primary ions. Experiments carried out using C60+ and Ar4000+ bombardment on silicon show that yields of negative secondary silicon ions can be optimized in the same way as by Ga+ and Cs+ bombardment. Both for monatomic and cluster ion bombardment, the optimization does not depend on the primary ion species. Hence, it can be assumed that the silicon results are also valid for other cluster primary ions and that results obtained for monatomic ion bombardment on other semiconductor and metal samples are also valid for cluster ion bombardment. In SIMS, cluster primary ions are also largely used for the analysis of organic matter. For polycarbonate, our results show that Ar4000+ bombardment combined with cesium flooding enhances secondary ion signals by a factor of 6. This can be attributed to the removal of charging effects and/or reduced fragmentation, but no major influence on ionization processes can be observed. The use of cesium flooding for the imaging of cells was also investigated and a significant enhancement of secondary ion yields was observed. Hence, cesium flooding has also a vast potential for SIMS analyses with cluster ion bombardment. PMID:26378890

  9. Optimization of fullerene-based negative tone chemically amplified fullerene resist for extreme ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Frommhold, A.; Yang, D. X.; McClelland, A.; Xue, X.; Ekinci, Y.; Palmer, R. E.; Robinson, A. P. G.

    2014-03-01

    While the technological progress of Next Generation Lithography (NGL) steadily continues, further progress is required before successful insertion in high volume manufacturing is possible. A key issue is the development of new resists suitable to achieve higher lithographic resolution with acceptable sensitivity and line edge roughness. Molecular resists have been a primary focus of interest for NGL because they promise high resolution and small line edge roughness (LER), but no suitable resist candidate has emerged yet that fulfills all of the industry's criteria. We have previously shown first extreme ultraviolet lithography (EUVL) exposures for a new fullerene derivative based three-component negative tone chemically amplified resist with suitable properties close to or within the target range of the resist metrics as set out in the International Technology Roadmap for Semiconductors for 2016. Here we present the results of our efforts to optimize the EUVL performance of our resist system especially with regards to LER.

  10. Hydrogenated fullerenes dimer, peanut and capsule: An atomic comparison

    NASA Astrophysics Data System (ADS)

    EL-Barbary, A. A.

    2016-04-01

    Hydrogenated fullerenes are detected in the Universe in space but their identification is still unsolved task. Therefore, this paper provides useful information about hydrogenated fullerenes (dimer, peanut and capsule) using DFT method at the B3LYP/6-31G(d) level of theory. The stability, geometric structures, hydrogen adsorption energies and NMR chemical shifts are calculated. The results show that the energy of most stable isomer of C118 dimer is lower than the energies sum of C60 and C58 cages by 1.77 eV and the energy per carbon atom of C144 capsule is more stable than C60 cage by 126.98 meV. Also, endohedral Ti-doped C118 dimer and C128 peanut are found to be most stable structures than exohedral Ti-doped C118 dimer and C128 peanut by 2.19 eV/Ti and 3.52 eV/Ti, respectively. The hydrogenation process is found to be enhanced (especially at the caps) for endohedral Ti-doped C118 dimer and C128 peanut through electronic surface modifications. The most active hydrogenation sites are selected and it is found that the most stable hydrogenation sites are Houts1 and Houts3 for fullerenes and endohedral Ti-doped fullerenes, respectively.

  11. Fullerenes, fulleranes and polycyclic aromatic hydrocarbons in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Becker, L.; Bunch, T. E.

    1997-01-01

    In this paper, we confirm our earlier observations of fullerenes (C60 and C70) in the Allende meteorite (Becker et al., 1994a, 1995). Fullerene C60 was also detected in two separate C-rich (approximately 0.5-1.0%) dark inclusions (Heymann et al., 1987) that were hand picked from the Allende sample. The amounts of C60 detected were approximately 5 and approximately 10 ppb, respectively, which is considerably less than what was detected in the Allende 15/21 sample (approximately 100 ppb; Becker et al., 1994a, 1995). This suggests that fullerenes are heterogeneously distributed in the meteorite. In addition, we present evidence for fulleranes, (C60Hx), detected in separate samples by laser desorption (reflectron) time-of-flight (TOF) mass spectrometry (LDMS). The LDMS spectra for the Allende extracts were remarkably similar to the spectra generated for the synthetic fullerane mixtures. Several fullerane products were synthesized using a Rh catalyst (Becker et al., 1993a) and separated using high-performance liquid chromatography (HPLC). Polycyclic aromatic hydrocarbons (PAHs) were also observed ppm levels) that included benzofluoranthene and corannulene, a cup-shaped molecule that has been proposed as a precursor molecule to the formation of fullerenes in the gas phase (Pope et al., 1993).

  12. Perovskite solar cells: High voltage from ordered fullerenes

    NASA Astrophysics Data System (ADS)

    Yan, Yanfa

    2016-01-01

    The open-circuit voltage is one of the parameters determining the efficiency of solar cells in converting solar radiation to electricity. Reducing the structural disorder in fullerene electron-transport layers is now shown to significantly improve the open-circuit voltage of perovskite solar cells.

  13. Supersymmetry in spherical molecules and fullerenes under perpendicular magnetic fields.

    PubMed

    Jakubský, V; Kuru, S; Negro, J; Tristao, S

    2013-04-24

    Methods of supersymmetric quantum mechanics are used to obtain analytical solutions for massless Dirac electrons in spherical molecules, including fullerenes, in the presence of magnetic fields. The solutions for Dirac massive charges are also obtained via the solutions of the Dirac-Weyl equation. PMID:23553418

  14. Preferable orientation of spherical fullerene inside boron nitride nanotubes

    NASA Astrophysics Data System (ADS)

    Ma, Fengxian; Yao, Zhen; Yao, Mingguang; Liu, Ran; Zou, Bo; Cui, Tian; Liu, Bingbing

    2013-02-01

    We provide a systematic analytical method for preferable orientation calculations of spherical fullerenes in single-walled boron nitride nanotubes. Based on the reaction energy calculations, both the minimum entering radii and the energetically favorable radii for encapsulating C60, C80 and C180 molecules in boron nitride nanotubes have been proposed. The van der Waals energy as a function of the various orientations of the encapsulated fullerene molecule is shown by a potential contour map, from which we find that the low-energy state appears in the symmetry axis orientation of the encapsulated fullerene molecules with a different size. We thus propose a new systematic analytical method for optimal orientation predictions of spherical fullerenes in the confinement condition, which is based on the symmetry axis but not the method proposed in previous literature, such as using pentagons, double-bonds, and hexagons to analyze the preferable orientation of confined C60. Our results show that the C60 molecule in boron nitride nanotubes exhibits three lowest energy states corresponding to the five-, two- and three-fold axis orientations in three radii intervals, while only two preferable orientationsthe five- and three-fold axis orientations have been observed for encapsulated C80 and C180 molecules.

  15. Fullerene-Based Symmetry in Hibiscus rosa-sinensis Pollen

    PubMed Central

    Andrade, Kleber; Guerra, Sara; Debut, Alexis

    2014-01-01

    The fullerene molecule belongs to the so-called super materials. The compound is interesting due to its spherical configuration where atoms occupy positions forming a mechanically stable structure. We first demonstrate that pollen of Hibiscus rosa-sinensis has a strong symmetry regarding the distribution of its spines over the spherical grain. These spines form spherical hexagons and pentagons. The distance between atoms in fullerene is explained applying principles of flat, spherical, and spatial geometry, based on Euclids Elements book, as well as logic algorithms. Measurements of the pollen grain take into account that the true spine lengths, and consequently the real distances between them, are measured to the periphery of each grain. Algorithms are developed to recover the spatial effects lost in 2D photos. There is a clear correspondence between the position of atoms in the fullerene molecule and the position of spines in the pollen grain. In the fullerene the separation gives the idea of equal length bonds which implies perfectly distributed electron clouds while in the pollen grain we suggest that the spines being equally spaced carry an electrical charge originating in forces involved in the pollination process. PMID:25003375

  16. Quenching and Sensitizing Fullerene Photoreactions by Natural Organic Matter

    EPA Science Inventory

    Effects of natural organic matter (NOM) on the photoreaction kinetics of fullerenes (i.e., C60 and fullerenol) were investigated using simulated sunlight and monochromatic radiation (365 nm). NOM from several sources quenched (slowed) the photoreaction of C60 aggregates in water ...

  17. Nanostructure enhanced ionic transport in fullerene reinforced solid polymer electrolytes.

    PubMed

    Sun, Che-Nan; Zawodzinski, Thomas A; Tenhaeff, Wyatt E; Ren, Fei; Keum, Jong Kahk; Bi, Sheng; Li, Dawen; Ahn, Suk-Kyun; Hong, Kunlun; Rondinone, Adam J; Carrillo, Jan-Michael Y; Do, Changwoo; Sumpter, Bobby G; Chen, Jihua

    2015-03-28

    Solid polymer electrolytes, such as polyethylene oxide (PEO) based systems, have the potential to replace liquid electrolytes in secondary lithium batteries with flexible, safe, and mechanically robust designs. Previously reported PEO nanocomposite electrolytes routinely use metal oxide nanoparticles that are often 5-10 nm in diameter or larger. The mechanism of those oxide particle-based polymer nanocomposite electrolytes is under debate and the ion transport performance of these systems is still to be improved. Herein we report a 6-fold ion conductivity enhancement in PEO/lithium bis(trifluoromethanesulfonyl) imide (LiTFSI)-based solid electrolytes upon the addition of fullerene derivatives. The observed conductivity improvement correlates with nanometer-scale fullerene crystallite formation, reduced crystallinities of both the (PEO)6:LiTFSI phase and pure PEO, as well as a significantly larger PEO free volume. This improved performance is further interpreted by enhanced decoupling between ion transport and polymer segmental motion, as well as optimized permittivity and conductivity in bulk and grain boundaries. This study suggests that nanoparticle induced morphological changes, in a system with fullerene nanoparticles and no Lewis acidic sites, play critical roles in their ion conductivity enhancement. The marriage of fullerene derivatives and solid polymer electrolytes opens up significant opportunities in designing next-generation solid polymer electrolytes with improved performance. PMID:25733054

  18. The biological mechanisms and physicochemical characteristics responsible for driving fullerene toxicity.

    PubMed

    Johnston, Helinor J; Hutchison, Gary R; Christensen, Frans M; Aschberger, Karin; Stone, Vicki

    2010-04-01

    This review provides a comprehensive critical review of the available literature purporting to assess the toxicity of carbon fullerenes. This is required as prior to the widespread utilization and production of fullerenes, it is necessary to consider the implications of exposure for human health. Traditionally, fullerenes are formed from 60 carbon atoms, arranged in a spherical cage-like structure. However, manipulation of surface chemistry and molecular makeup has created a diverse population of fullerenes, which exhibit drastically different behaviors. The cellular processes that underlie observed fullerene toxicity will be discussed and include oxidative, genotoxic, and cytotoxic responses. The antioxidant/cytoprotective properties of fullerenes (and the attributes responsible for driving these phenomena) have been considered and encourage their utilization within the treatment of oxidant-mediated disease. A number of studies have focused on improving the water solubility of fullerenes in order to enable their exploitation within biological systems. Manipulating fullerene water solubility has included the use of surface modifications, solvents, extended stirring, and mechanical processes. However, the ability of these processes to also impact on fullerene toxicity requires assessment, especially when considering the use of solvents, which particularly appear to enhance fullerene toxicity. A number of the discussed investigations were not conducted to reveal if fullerene behavior was due to their nanoparticle dimensions but instead addressed the biocompatibility and toxicity of fullerenes. The hazards to human health, associated with fullerene exposure, are uncertain at this time, and further investigations are required to decipher such effects before an effective risk assessment can be conducted. PMID:19901017

  19. Effect of nitrogen atomic percentage on N+-bombarded MWCNTs in cytocompatibility and hemocompatibility

    PubMed Central

    2014-01-01

    N+-bombarded multi-walled carbon nanotubes (N+-bombarded MWCNTs), with different nitrogen atomic percentages, were achieved by different N ion beam currents using ion beam-assisted deposition (IBAD) on MWCNTs synthesized by chemical vapor deposition (CVD). Characterizations of N+-bombarded MWCNTs were evaluated by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, and contact angle. For comparison, the in vitro cytocompatibility of the N+-bombarded MWCNTs with different N atomic percentages was assessed by cellular adhesion investigation using human endothelial cells (EAHY926) and mouse fibroblast cells (L929), respectively. The results showed that the presence of nitrogen in MWCNTs accelerated cell growth and proliferation of cell culture. The higher nitrogen content of N+-bombarded MWCNTs, the better cytocompatibility. In addition, N+-bombarded MWCNTs with higher N atomic percentage displayed lower platelet adhesion rate. No hemolysis can be observed on the surfaces. These results proved that higher N atomic percentage led N+-bombarded MWCNTs to better hemocompatibility. PMID:24666845

  20. Effect of nitrogen atomic percentage on N+-bombarded MWCNTs in cytocompatibility and hemocompatibility

    NASA Astrophysics Data System (ADS)

    Zhao, Mengli; Cao, Ye; Liu, Xiaoqi; Deng, Jianhua; Li, Dejun; Gu, Hanqing

    2014-03-01

    N+-bombarded multi-walled carbon nanotubes (N+-bombarded MWCNTs), with different nitrogen atomic percentages, were achieved by different N ion beam currents using ion beam-assisted deposition (IBAD) on MWCNTs synthesized by chemical vapor deposition (CVD). Characterizations of N+-bombarded MWCNTs were evaluated by X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Raman spectroscopy, and contact angle. For comparison, the in vitro cytocompatibility of the N+-bombarded MWCNTs with different N atomic percentages was assessed by cellular adhesion investigation using human endothelial cells (EAHY926) and mouse fibroblast cells (L929), respectively. The results showed that the presence of nitrogen in MWCNTs accelerated cell growth and proliferation of cell culture. The higher nitrogen content of N+-bombarded MWCNTs, the better cytocompatibility. In addition, N+-bombarded MWCNTs with higher N atomic percentage displayed lower platelet adhesion rate. No hemolysis can be observed on the surfaces. These results proved that higher N atomic percentage led N+-bombarded MWCNTs to better hemocompatibility.

  1. Ripening of subsurface amorphous C clusters formed by low energy He ion bombardment of graphite

    NASA Astrophysics Data System (ADS)

    Kappel, M.; Küppers, J.

    1999-10-01

    Surfaces of highly oriented pyrolytic graphite (HOPG) were bombarded with 100 eV and 500 eV He ions at ion doses of a few 10 15 cm 2 and temperatures ranging from 300 K to 800 K. AFM images were recorded to investigate the topography of the surfaces after ion bombardment. Supplementary electron energy loss (EEL) and thermal desorption (TD) spectra were measured to determine the C sp 2 fraction of the bombarded surfaces and the amount of trapped He. The temperature at which He ion bombardment was performed had a drastic effect on the surface structure and topography of the targets on the angstrom-scale and micrometer-scale as well. At 300 K, limited defect atom transport revealed an amorphous but relatively flat HOPG surface. Bombardment at 400 K leads to a granular structure of small protrusions in micrometer-scale AFM images, however, without crystalline order on the surface. The protrusions are due to the formation of subsurface clusters of carbon formed by atoms displaced by ion irradiation. Towards higher temperatures during bombardment the clusters agglomerate and cause the surface layers to bend upwards in dome-like shapes. Simultaneously, the microscopic order of the graphite lattice recovers. At 800 K large areas of the top layer retain their order during bombardment, however, a small number of domes indicate that there still exist some subsurface C clusters. The cluster-cluster distance deduced from the dome distribution indicates that the clusters grow through a ripening process. Annealing of graphite at high temperatures subsequent to ion bombardment at low temperatures is much less effective for recovering the surface crystallinity than ion bombardment at high temperature.

  2. [60]Fullerene Displacement from (Dihapto-Buckminster-Fullerene) Pentacarbonyl Tungsten(0): An Experiment for the Inorganic Chemistry Laboratory, Part II

    ERIC Educational Resources Information Center

    Cortes-Figueroa, Jose E.; Moore-Russo, Deborah A.

    2006-01-01

    The kinetics experiments on the ligand-C[subscript 60] exchange reactions on (dihapto-[60]fullerene) pentacarbonyl tungsten(0), ([eta][superscript 2]-C[subscript 60])W(CO)[subscript 5], form an educational activity for the inorganic chemistry laboratory that promotes graphical thinking as well as the understanding of kinetics, mechanisms, and the…

  3. [60]Fullerene Displacement from (Dihapto-Buckminster-Fullerene) Pentacarbonyl Tungsten(0): An Experiment for the Inorganic Chemistry Laboratory, Part II

    ERIC Educational Resources Information Center

    Cortes-Figueroa, Jose E.; Moore-Russo, Deborah A.

    2006-01-01

    The kinetics experiments on the ligand-C[subscript 60] exchange reactions on (dihapto-[60]fullerene) pentacarbonyl tungsten(0), ([eta][superscript 2]-C[subscript 60])W(CO)[subscript 5], form an educational activity for the inorganic chemistry laboratory that promotes graphical thinking as well as the understanding of kinetics, mechanisms, and the

  4. Positronium origin of 476 keV galactic feature.

    NASA Technical Reports Server (NTRS)

    Clayton, D. D.

    1973-01-01

    Leventhal noticed that the gamma-ray spectrum due to the annihilation of positronium, which consists of two 511 keV photons from the singlet state and three photons from the triplet state, produces a spectral feature with an apparent peak at an energy less than 511 keV when viewed with a gamma-ray telescope having a Gaussian energy resolution. He calculated that the observed peak will lie at 490 keV. The author calculates that if the positronium spectrum sits atop a steeply falling continuum due to other sources, then the apparent peak can easily fall near 476 keV where it was observed. It is shown that explosive nucleosynthesis is a plausible source of the positrons.

  5. Compositional Evolution of Saturn's Rings Due to Meteoroid Bombardment

    NASA Technical Reports Server (NTRS)

    Cuzzi, J.; Estrada, P.; Young, Richard E. (Technical Monitor)

    1997-01-01

    In this paper we address the question of compositional evolution in planetary ring systems subsequent to meteoroid bombardment. The huge surface area to mass ratio of planetary rings ensures that this is an important process, even with current uncertainties on the meteoroid flux. We develop a new model which includes both direct deposition of extrinsic meteoritic "pollutants", and ballistic transport of the increasingly polluted ring material as impact ejecta. Our study includes detailed radiative transfer modeling of ring particle spectral reflectivities based on refractive indices of realistic constituents. Voyager data have shown that the lower optical depth regions in Saturn's rings (the C ring and Cassini Division) have darker and less red particles than the optically thicken A and B rings. These coupled structural-compositional groupings have never been explained; we present and explore the hypothesis that global scale color and compositional differences in the main rings of Saturn arise naturally from extrinsic meteoroid bombardment of a ring system which was initially composed primarily, but not entirely, of water ice. We find that the regional color and albedo differences can be understood if all ring material was initially identical (primarily water ice, based on other data, but colored by tiny amounts of intrinsic reddish, plausibly organic, absorber) and then evolved entirely by addition and mixing of extrinsic, nearly neutrally colored. plausibly carbonaceous material. We further demonstrate that the detailed radial profile of color across the abrupt B ring - C ring boundary can.constrain key unknown parameters in the model. Using new alternates of parameter values, we estimate the duration of the exposure to extrinsic meteoroid flux of this part of the rings, at least, to be on the order of 10(exp 8) years. This conclusion is easily extended by inference to the Cassini Division and its surroundings as well. This geologically young "age" is compatible with timescales estimated elsewhere based on the evolution of ring structure due to ballistic transport, and also with other "short timescales" estimated on the grounds of gravitational torques. However, uncertainty in the flux of interplanetary debris and in the ejects yield may preclude ruling out a ring age as old as the solar system at this time.

  6. Computer simulations of material ejection during C60 and Arm bombardment of octane and β-carotene

    NASA Astrophysics Data System (ADS)

    Palka, G.; Kanski, M.; Maciazek, D.; Garrison, B. J.; Postawa, Z.

    2015-06-01

    Molecular dynamics (MD) computer simulations are used to investigate material ejection and fragment formation during keV C60 and Arm (m = 60, 101, 205, 366, 872 and 2953) bombardment of organic solids composed from octane and β-carotene molecules at 0° and 45° impact angle. Both systems are found to sputter efficiently. For the octane system, material removal occurs predominantly by ejection of intact molecules, while fragment emission is a significant ejection channel for β-carotene. A difference in the molecular dimensions is proposed to explain this observation. It has been shown that the dependence of the sputtering yield Y on the primary kinetic energy E and the cluster size n can be expressed in a simplified form if represented in reduced units. A linear and nonlinear dependence of the Y/n on the E/n are identified and the position of the transition point from the linear to nonlinear regions depends on the size of the cluster projectile. The impact angle has a minor influence on the shape of the simplified representation.

  7. Effect of proton bombardment on InAs dots and wetting layer in laser structures

    SciTech Connect

    O'Driscoll, I.; Blood, P.; Smowton, P. M.; Sobiesierski, A.; Gwilliam, R.

    2012-06-25

    The effect of proton bombardment on carrier lifetime and photoluminescence of InAs quantum dots was measured. Optical absorption and transmission electron microscopy show the dots retain their integrity under bombardment. A decrease in ground state photoluminescence with increasing dose is not explained by the decrease in dot carrier lifetime alone, but also by bombardment-induced non-radiative recombination in the wetting layer, which reduces the dot electron population at fixed excitation. To exploit the relative radiation immunity of quantum dots, it is necessary to maximise the dot density and capture probability per dot to minimize the effect of wetting layer recombination.

  8. Changes in a surface of polycrystalline aluminum upon bombardment with argon ions

    NASA Astrophysics Data System (ADS)

    Ashkhotov, O. G.; Ashkhotova, I. B.; Bliev, A. P.; Magkoev, T. T.; Krymshokalova, D. A.

    2014-10-01

    The interaction between argon ions and a natural oxide layer of polycrystalline aluminum is studied via Auger electron (AE) and electron energy loss (EEL) spectroscopy. It is found that bombardment with argon ions whose energy is lower than the Al2O3 sputtering threshold results in the accumulation of bombarding ions in interstitial surface voids, thus forming a supersaturated solid solution of target atoms and bombarding ions of argon and nitrogen entrapped by the ion beam from the residual gas of the working chamber of the spectrometer.

  9. Effect of Boron doping on the electronic properties of the fullerenes of different sizes

    SciTech Connect

    Agnihotri, Deepak; Sharma, Hitesh

    2011-12-12

    We report the results of the effect of Boron doping in C{sub n}; n = 28, 32, 36, 40, 44, 50 and 60 using the first principle calculation based on density functional theory. The HOMO-LUMO gap changes significantly with the decreasing fullerene size below C{sub 60}, with maximum gap observed for C{sub 32}. The HOMO-LUMO gap of Boron doped fullerenes varies significantly w.r.t. pure fullerenes. Also, the gap decreases for C{sub n-m}B{sub m}X, the boron doped fullerenes with exohedral alkali metals for n = 28, 32, 36, 40, 44, 50 and 60; m = 1 to 4; X = Li, Na and K. The Mulliken charge transfer from the exohedral alkali metals towards the various fullerene cages is altered marginally by the boron doping in fullerenes and follows the order K>Na>Li.

  10. Interaction of C60 fullerenes with asymmetric and curved lipid membranes: a molecular dynamics study.

    PubMed

    Cherniavskyi, Yevhen K; Ramseyer, Christophe; Yesylevskyy, Semen O

    2016-01-01

    Interaction of fullerenes with asymmetric and curved DOPC/DOPS bicelles is studied by means of coarse-grained molecular dynamics simulations. The effects caused by asymmetric lipid composition of the membrane leaflets and the curvature of the membrane are analyzed. It is shown that the aggregates of fullerenes prefer to penetrate into the membrane in the regions of the moderately positive mean curvature. Upon penetration into the hydrophobic core of the membrane fullerenes avoid the regions of the extreme positive or the negative curvature. Fullerenes increase the ordering of lipid tails, which are in direct contact with them, but do not influence other lipids significantly. Our data suggest that the effects of the membrane curvature should be taken into account in the studies concerning permeability of the membranes to fullerenes and fullerene-based drug delivery systems. PMID:26608905

  11. Figure of merit enhancement in bismuth telluride alloys via fullerene-assisted microstructural refinement

    NASA Astrophysics Data System (ADS)

    Gothard, N. W.; Tritt, T. M.; Spowart, J. E.

    2011-07-01

    Nanocomposite materials based on bismuth telluride with fullerene additions have been synthesized via ball milling and spark plasma sintering. The impact of fullerene addition upon the composites is studied with respect to both fullerene volume percentage and ball-mill duration. It is demonstrated that fullerenes can engage in significant microstructural refinement even when present in small quantities. The lattice thermal conductivity, electrical conductivity, Seebeck coefficient, and Hall coefficient are analyzed with a view to the impact of fullerene incorporation upon these properties. Fullerene-assisted microstructural refinement causes a decrease both in lattice thermal conductivity and electrical conductivity, but a corresponding increase in the Seebeck coefficient results in an enhancement in the figure of merit at low volume fractions.

  12. Two-chamber configuration of Bio-Nano electron cyclotron resonance ion source for fullerene modification

    NASA Astrophysics Data System (ADS)

    Uchida, T.; Rácz, R.; Muramatsu, M.; Kato, Y.; Kitagawa, A.; Biri, S.; Yoshida, Y.

    2016-02-01

    We report on the modification of fullerenes with iron and chlorine using two individually controllable plasmas in the Bio-Nano electron cyclotron resonance ion source (ECRIS). One of the plasmas is composed of fullerene and the other one is composed of iron and chlorine. The online ion beam analysis allows one to investigate the rate of the vapor-phase collisional modification process in the ECRIS, while the offline analyses (e.g., liquid chromatography-mass spectrometry) of the materials deposited on the plasma chamber can give information on the surface-type process. Both analytical methods show the presence of modified fullerenes such as fullerene-chlorine, fullerene-iron, and fullerene-chlorine-iron.

  13. Back-bombardment compensation in microwave thermionic electron guns

    NASA Astrophysics Data System (ADS)

    Kowalczyk, Jeremy M. D.; Madey, John M. J.

    2014-12-01

    The development of capable, reliable, and cost-effective compact electron beam sources remains a long-standing objective of the efforts to develop the accelerator systems needed for on-site research and industrial applications ranging from electron beam welding to high performance x-ray and gamma ray light sources for element-resolved microanalysis and national security. The need in these applications for simplicity, reliability, and low cost has emphasized solutions compatible with the use of the long established and commercially available pulsed microwave rf sources and L-, S- or X-band linear accelerators. Thermionic microwave electron guns have proven to be one successful approach to the development of the electron sources for these systems providing high macropulse average current beams with picosecond pulse lengths and good emittance out to macropulse lengths of 4-5 microseconds. But longer macropulse lengths are now needed for use in inverse-Compton x-ray sources and other emerging applications. We describe in this paper our approach to extending the usable macropulse current and pulse length of these guns through the use of thermal diffusion to compensate for the increase in cathode surface temperature due to back-bombardment.

  14. Optical radiation from regions downstream of mercury bombardment thrusters.

    NASA Technical Reports Server (NTRS)

    Milder, N. L.; Sovey, J. S.

    1972-01-01

    Use of a 0.5-m focal length, plane grating monochromator to measure the radiance of spectral radiation emanating from regions downstream of a mercury bombardment thrustor in the wavelength range investigated was 2800 to 6000 A. This radiation was due primarily to the radiative decay of excited mercury atoms exhausted from the thrustor. Radiance values ranged from 10 to the minus 11th to 10 to the min scm/ster varying with wavelength. For resonant radiation, the spectral radiance may exceed 10 to the minus 8th W/sq cm/ster. From such radiance measurements, it was concluded that the thrustor background radiation should not interfere with the control functions of a star tracker viewing through the thrustor exhaust, provided that the tracker is designed to operate with a sufficiently small field of view. Problems may be encountered, however, during the spacecraft acquisition phase where a larger field of view may be required. Here the thrustor exhaust radiation may be comparable to the star light flux. This problem may be circumvented by locating the tracker view axis so as not to view downstream of the thrustor.

  15. Fast atom bombardment tandem mass spectrometry of carotenoids

    SciTech Connect

    van Breeman, R.B.; Schmitz, H.H.; Schwartz, S.J.

    1995-02-01

    Positive ion fast atom bombardment (FAB) tandem mass spectrometry (MS-MS) using a double-focusing mass spectrometer with linked scanning at constant B/E and high-energy collisionally activated dissociation (CAD) was used to differentiate 17 different cartenoids, including {beta}-apo-8{prime}- carotenal, astaxanthin, {alpha}-carotene, {beta}-carotene, {gamma}-carotene, {zeta}-carotene, canthaxanthin, {beta}-cryptoxanthin, isozeaxanthin bis (pelargonate), neoxanthin, neurosporene, nonaprene, lutein, lycopene, phytoene, phytofluene, and zeaxanthin. The carotenoids were either synthetic or isolated from plant tissues. The use of FAB ionization minimized degradation or rearrangement of the carotenoid structures due to the inherent thermal instability generally ascribed to these compounds. Instead of protonated molecules, both polar xanthophylls and nonpolar carotenes formed molecular ions, M{sup {center_dot}+}, during FAB ionization. Following collisionally activated dissociation, fragment ions of selected molecular ion precursors showed structural features indicative of the presence of hydroxyl groups, ring systems, ester groups, and aldehyde groups and the extent of aliphatic polyene conjugation. The fragmentation patterns observed in the mass spectra herein may be used as a reference for the structural determination of carotenoids isolated from plant and animal tissues. 18 refs., 4 figs.

  16. Wavelength tunability of ion-bombardment-induced ripples on sapphire

    SciTech Connect

    Zhou Hua; Wang Yiping; Zhou Lan; Headrick, Randall L.; Oezcan, Ahmet S.; Wang Yiyi; Oezaydin, Goezde; Ludwig, Karl F. Jr.; Siddons, D. Peter

    2007-04-15

    A study of ripple formation on sapphire surfaces by 300-2000 eV Ar{sup +} ion bombardment is presented. Surface characterization by in-situ synchrotron grazing incidence small angle x-ray scattering and ex-situ atomic force microscopy is performed in order to study the wavelength of ripples formed on sapphire (0001) surfaces. We find that the wavelength can be varied over a remarkably wide range--nearly two orders of magnitude--by changing the ion incidence angle. Within the linear theory regime, the ion induced viscous flow smoothing mechanism explains the general trends of the ripple wavelength at low temperature and incidence angles larger than 30 deg. . In this model, relaxation is confined to a few nm thick damaged surface layer. The behavior at high temperature suggests relaxation by surface diffusion. However, strong smoothing is inferred from the observed ripple wavelength near normal incidence, which is not consistent with either surface diffusion or viscous flow relaxation.

  17. Actinide production from xenon bombardments of curium-248

    SciTech Connect

    Welch, R.B.

    1985-01-01

    Production cross sections for many actinide nuclides formed in the reaction of /sup 129/Xe and /sup 132/Xe with /sup 248/Cm at bombarding energies slightly above the coulomb barrier were determined using radiochemical techniques to isolate these products. These results are compared with cross sections from a /sup 136/Xe + /sup 248/Cm reaction at a similar energy. When compared to the reaction with /sup 136/Xe, the maxima in the production cross section distributions from the more neutron deficient projectiles are shifted to smaller mass numbers, and the total cross section increases for the production of elements with atomic numbers greater than that of the target, and decreases for lighter elements. These results can be explained by use of a potential energy surface (PES) which illustrates the effect of the available energy on the transfer of nucleons and describes the evolution of the di-nuclear complex, an essential feature of deep-inelastic reactions (DIR), during the interaction. The other principal reaction mechanism is the quasi-elastic transfer (QE). Analysis of data from a similar set of reactions, /sup 129/Xe, /sup 132/Xe, and /sup 136/Xe with /sup 197/Au, aids in explaining the features of the Xe + Cm product distributions, which are additionally affected by the depletion of actinide product yields due to deexcitation by fission. The PES is shown to be a useful tool to predict the general features of product distributions from heavy ion reactions.

  18. Electron emission from surfaces resulting from low energy positron bombardment

    NASA Astrophysics Data System (ADS)

    Mukherjee, S.; Shastry, K.; Weiss, A. H.

    2009-03-01

    Measurements of the energy distribution of electrons resulting from very low energy positron bombardment of a polycrystalline Au and Cu(100) surfaces provide evidence for a single step transition from an unbound scattering state to an image potential bound state. The primary positron energy threshold for secondary electron emission and cutoff in the secondary electron energy spectra are consistent with a process in which an incident positrons make a transition from a scattering state to a surface-image potential bound while transferring all of the energy difference to an outgoing secondary electron. Estimates of the probability of this process as a function of incident positron energy are also presented. Background free Auger spectra of the MVV transition in Cu and the OVV transition in Au were obtained by setting the incident positron beam energy below the secondary electron emission threshold. Auger electron emission resulted from the annihilation of surface state positrons with core electrons. The low energy tail associated with the low energy CVV Auger transitions in Cu and Au were found to have integrated intensity several times larger than Auger peak providing strong evidence for multi-electron Auger processes.

  19. Electron emission from surfaces resulting from low energy positron bombardment

    NASA Astrophysics Data System (ADS)

    Mukherjee, Saurabh

    Measurements of the secondary electron energy spectra resulting from very low energy positron bombardment of a polycrystalline Au and Cu (100) surfaces are presented that provide evidence for a single step transition from an unbound scattering state to an image potential bound state. The primary positron energy threshold for secondary electron emission and energy cutoff of the positron induced secondary electron energy peak are consistent with an Auger like process in which an incident positron make a transition from a scattering state to a surface-image potential bound while transferring all of the energy difference to an outgoing secondary electron. We term this process: the Auger mediated quantum sticking effect (AQSE). The intensities of the positron induced secondary electron peak are used to estimate the probability of this process as a function of incident positron energy. Positron annihilation induced Auger spectra (PAES) of Cu and Au are presented that are free of all primary beam induced secondary electron background. This background was eliminated by setting the positron beam energy below AQSE threshold. The background free PAES spectra obtained include the first measurements of the low energy tail of CVV Auger transitions all the way down to zero kinetic energy. The integrated intensity of this tail is several times larger than Auger peak itself which provides strong evidence for multi-electron Auger processes.

  20. Determination of Betaines by Fast Atom Bombardment Mass Spectrometry 1

    PubMed Central

    Rhodes, David; Rich, Patrick J.; Myers, Ann C.; Reuter, Carol C.; Jamieson, Gene C.

    1987-01-01

    A rapid, sensitive, and selective method for the determination of betaines is described and discussed. The method entails derivatizing the quaternary ammonium compounds to increase their sensitivity to detection by fast atom bombardment mass spectrometry. Sensitivity of detection increases markedly as the length of the carbon chain of the alcohol used to esterify the betaine carboxylic acid group is increased (C4 > C3 > C2 > C1 > C0). The lower limit of detection of glycine betaine as the n-propyl ester is 0.05 nanomole per microliter of glycerol. Betaine aldehyde can be readily derivatized to the di-n-butyl or di-n-propyl acetal derivatives which exhibit lower limits of detection of about 5 picomoles and 10 picomoles per microliter of glycerol, respectively. Accurate quantification of these compounds is accomplished by the use of deuterium labeled internal standards or quaternary ammonium compound homologs of distinct mass. Methods for the synthesis of these internal standards are reported. Some applications of these methods are illustrated with stable isotope tracer studies on the kinetics of metabolism of choline to betaine aldehyde and glycine betaine in spinach leaf discs, and the identification of several Zea mays genotypes which appear deficient in glycine betaine. Tracer studies with deuterium labeled betaine aldehyde suggest that the deficiency of glycine betaine in one sweet corn hybrid is probably not due to a deficiency in the capacity to oxidize betaine aldehyde. PMID:16665522

  1. Comet impacts and chemical evolution on the bombarded earth

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.; Aggarwal, Hans

    1992-01-01

    Amino acids yields for previously published shock tube experiments are used with minimum Cretaceous-Tertiary (K/T) impactor mass and comet composition to predict AIB amino acid K/T boundary sediment column density. The inferred initial concentration of all amino acids in the K/T sea and in similar primordial seas just after 10 km comet impacts would have been at least 10 exp -7 M. However, sinks for amino acids must also be considered in calculating amino acid concentrations after comet impacts and in assessing the contribution of comets to the origin of life. The changing concentration of cometary amino acids due to ultraviolet light is compared with the equilibrium concentration of amino acids produced in the sea from corona discharge in the atmosphere, deposition in water, and degradation by ultraviolet light. Comets could have been more important than endogenous agents for initial evolution of amino acids. Sites favorable for chemical evolution of amino acids are examined, and it is concluded that chemical evolution could have occurred at or above the surface even during periods of intense bombardment of earth before 3.8 billion years ago.

  2. Compact Electron Gun Based on Secondary Emission Through Ionic Bombardment

    PubMed Central

    Diop, Babacar; Bonnet, Jean; Schmid, Thomas; Mohamed, Ajmal

    2011-01-01

    We present a new compact electron gun based on the secondary emission through ionic bombardment principle. The driving parameters to develop such a gun are to obtain a quite small electron gun for an in-flight instrument performing Electron Beam Fluorescence measurements (EBF) on board of a reentry vehicle in the upper atmosphere. These measurements are useful to characterize the gas flow around the vehicle in terms of gas chemical composition, temperatures and velocity of the flow which usually presents thermo-chemical non-equilibrium. Such an instrument can also be employed to characterize the upper atmosphere if placed on another carrier like a balloon. In ground facilities, it appears as a more practical tool to characterize flows in wind tunnel studies or as an alternative to complex electron guns in industrial processes requiring an electron beam. We describe in this paper the gun which has been developed as well as its different features which have been characterized in the laboratory. PMID:22163896

  3. Experimental Investigation of Neutral Species from Micrometeoroid Bombardment

    NASA Astrophysics Data System (ADS)

    Collette, A.; Sternovsky, Z.; Rocha, J. R.; Munsat, T. L.; Horanyi, M.

    2014-12-01

    Surface-boundary exospheres exist in a balance between source and loss processes. An important area of uncertainty, highlighted by the MESSENGER observations of Mg and Ca at Mercury, and the recently concluded LADEE observations at the Moon, is the role of micrometeoroid bombardment as a source process for liberating surface species. Unlike sputtering or photon stimulated desorption processes, the physics of micrometeoroid impacts are still poorly understood; in particular, no comprehensive model exists to predict partitioning of impact products between ejecta fragments, charged particles, and neutrals. We present initial experiments at the IMPACT dust accelerator facility (University of Colorado Boulder) aimed at directly measuring the fraction of neutral species liberated in micrometeoroid impacts. Simulated micrometeoroids (micron- and submicron-sized iron spheres) are fired at targets containing refractory elements, including fused silica (SiO2), sapphire (Al2O3), and magnesium fluoride (MgF2). Total quantities of specific impact-generated neutral species are measured using a mass spectrometer, as a function of impactor speed and mass, and compared with well-established scaling laws for charged particle production.

  4. Production of high-Q ions by laser bombardment method

    SciTech Connect

    Phaneuf, R.A.

    1980-01-01

    The expanding plasma produced when an intense pulse of laser radiation is focused in vacuum onto a solid target has been used as a source of highly stripped ions for collision cross-section measurements. Usable fluxes of carbon nuclei at energies of a few hundred eV/charge have been obtained by irradiation of graphite with pulses of CO/sub 2/ laser radiation at a focused power density of 3 x 10/sup 10/ W/cm/sup 2/. Bombardment of aluminum and iron targets at comparable power levels have yielded ions of maximum charges of 9 and 16, respectively. A time-of-flight apparatus has been constructed to utilize the laser source for measurement of electron capture cross sections for highly stripped ions in gases at energies in the few hundred eV/charge range. Apertures collimate an ion beam from the plasma blowoff, and an electrostatic analyzer selects ions from the expanding plasma which have the same energy per charge. The beam is directed through a gas target cell, charge analyzed once more by deceleration, and detected by a channel plate electron multiplier used in a current amplification mode. Electron capture cross sections have been measured for C/sup +q/ ions, q = 3, 4, 5 in H/sub 2/ at energies ranging from 150 to 1160 eV/charge.

  5. Effect of argon ion bombardment on amorphous silicon carbonitride films

    NASA Astrophysics Data System (ADS)

    Batocki, R. G. S.; Mota, R. P.; Honda, R. Y.; Santos, D. C. R.

    2014-04-01

    Amorphous silicon carbonitride (a-SiCN:H) films were synthesized by radiofrequency (RF) Plasma Enhanced Vapor Chemical Deposition (PECVD) using hexamethyldisilazane (HMDSN) as precursor compound. Then, the films were post-treated by Plasma Immersion Ion Implantation (PIII) in argon atmosphere from 15 to 60 min. The hardness of the film enhanced after ion implantation, and the sample treated at 45 min process showed hardness greater than sixfold that of the untreated sample. This result is explained by the crosslinking and densification of the structure. Films were exposed to oxygen plasma for determining of the etching rate. It decreased monotonically from 33 /min to 19 /min for the range of process time, confirming structural alterations. Hydrophobic character of the a-SiCN:H films were modified immediately after ion bombardment, due to incorporation of polar groups. However, the high wettability of the films acquired by the ion implantation was diminished after aging in air. Therefore, argon PIII made a-SiCN:H films mechanically more resistant and altered their hydrophobic character.

  6. Modeling Charge Transfer in Fullerene Collisions via Real-Time Electron Dynamics

    SciTech Connect

    Jakowski, Jacek; Irle, Stephan; Morokuma, Keiji; Sumpter, Bobby G

    2012-01-01

    An approach for performing real-time dynamics of electron transfer in a prototype redox reaction that occurs in reactive collisions between neutral and ionic fullerenes is discussed. The quantum dynamical simulations show that the electron transfer occurs within 60 fs directly preceding the collision of the fullerenes, followed by structural changes and relaxation of electron charge. The consequences of real-time electron dynamics are fully elucidated for the far from equilibrium processes of collisions between neutral and multiply charged fullerenes.

  7. Observation of fullerenes (C60-C70) associated with LDEF crater number 31

    NASA Technical Reports Server (NTRS)

    Radicatidibrozolo, Filippo; Fleming, R. H.; Bunch, T. E.

    1992-01-01

    The presence of fullerenes in and around the LDEF crater number 31 is reported. This crater has a high C level associated with it, and is interpreted as having been produced by the impact of a C-rich micrometeoroid. Fullerenes are large 3-D C structures, among which the species C sub 60 (MW 720) and C sub 70 (MW 840) are preeminent. Fullerenes have several UV absorption bands, hence fullerenes should be detectable using UV laser ionization time-of-flight mass spectrometry. We use a LIMA-2A instrument with pulsed UV laser (266 nm) to search for high mass C species associated with LDEF crater number 31. The mass range was 0 to 1200 amu. Low ablating laser power levels were used (less than or = 5 x 10 exp 7 W/sq. cm); 200 mass spectra were acquired and summed. We observed high mass signals near m/z 720, exhibiting 24 amu separation, which is characteristic of fullerenes. Alkali ion signals were also observed. Little or no C clusters of intermediate mass were observed. We interpret the signals around m/z 720 as fullerenes, mainly C sub 60+ with lower levels of C sub 70+. We propose that the mechanism that produces these signals is resonant multiphoton ionization (REMPI). This selective mechanism explains why low mass C cluster ions are not observed along with the fullerenes, since they have much higher ionization potentials. This finding is unexpected, since up to now the search for fullerenes in extraterrestrial materials has not been successful. We conclude that the fullerenes became associated with crater number 31 in space. Two alternative (and exciting) scenarios are being considered at this time: either the fullerenes were carried by the C-rich projectile that formed crater number 31, or the fullerenes formed upon impact with the LDEF. We show the results of experiments at the ARC Vertical Gun Facility, which may establish some constraints on the origin of the fullerenes.

  8. Tuning the interactions between electron spins in fullerene-based triad systems

    PubMed Central

    Lebedeva, Maria A; Chamberlain, Thomas W; Davies, E Stephen; Thomas, Bradley E; Schrder, Martin

    2014-01-01

    Summary A series of six fullerenelinkerfullerene triads have been prepared by the stepwise addition of the fullerene cages to bridging moieties thus allowing the systematic variation of fullerene cage (C60 or C70) and linker (oxalate, acetate or terephthalate) and enabling precise control over the inter-fullerene separation. The fullerene triads exhibit good solubility in common organic solvents, have linear geometries and are diastereomerically pure. Cyclic voltammetric measurements demonstrate the excellent electron accepting capacity of all triads, with up to 6 electrons taken up per molecule in the potential range between ?2.3 and 0.2 V (vs Fc+/Fc). No significant electronic interactions between fullerene cages are observed in the ground state indicating that the individual properties of each C60 or C70 cage are retained within the triads. The electronelectron interactions in the electrochemically generated dianions of these triads, with one electron per fullerene cage were studied by EPR spectroscopy. The nature of electronelectron coupling observed at 77 K can be described as an equilibrium between doublet and triplet state biradicals which depends on the inter-fullerene spacing. The shorter oxalate-bridged triads exhibit stronger spinspin coupling with triplet character, while in the longer terephthalate-bridged triads the intramolecular spinspin coupling is significantly reduced. PMID:24605154

  9. Non-fullerene acceptors: exciton dissociation with PTCDA versus C60.

    PubMed

    Dutton, Gregory J; Robey, Steven W

    2015-06-28

    Extensive development of new polymer and small molecule donors has helped produce a steady increase in the efficiency of organic photovoltaic (OPV) devices. However, OPV technology would also benefit from the introduction of non-fullerene acceptors. Unfortunately, efforts to replace fullerenes have typically led to significantly reduced efficiencies. A number of possible explanations for reduced efficiencies with non-fullerene acceptors compared to fullerene acceptors have been suggested, including the formation of unfavorable morphologies in non-fullerene systems and/or favorable excitation/carrier delocalization in fullerenes. In addition, enhanced exciton dissociation associated with fundamental characteristics of the fullerene molecular electronic states has also been suggested. We used time-resolved two-photon photoemission (TR-2PPE) to directly compare exciton dissociation at interfaces between zinc phthalocyanine (ZnPc) interfaces and the non-fullerene acceptor, perylene tetracarboxylic dianhydride (PTCDA) versus dissociation measured at the analogous interface with C60, and thus help discriminate between these potential explanations. Exciton dissociation rates are comparable for phthalocyanine interfaces with both acceptors, allowing us to suggest a hierarchy for the importance of various effects producing higher efficiencies with fullerene acceptors. PMID:26027544

  10. Bulk moduli of the silicon and germanium fullerenes Si60 and Ge60

    NASA Astrophysics Data System (ADS)

    Lunyakov, Yu. V.; Balagan, S. A.

    2015-06-01

    The bulk moduli of the silicon and germanium fullerenes Si60 and Ge60 of different symmetries have been calculated using the density functional theory method. It has been shown that the bulk moduli of metastable fullerenes of the highest symmetry I h have maximum values and exceed those of the corresponding bulk crystal structures by a factor of 1.5-1.7. The most stable fullerenes have the symmetry C 1 and lower bulk moduli. The bulk moduli of the silicon and germanium fullerenes Si60 and Ge60 exceed the bulk moduli of the corresponding crystal structures by factors of 1.44 and 1.38-1.40, respectively.

  11. The antioxidative effect of fullerenes during the peroxidation of methyl linoleate in toluene.

    PubMed

    Kadowaki, Akio; Iwamoto, Satoshi; Yamauchi, Ryo

    2012-01-01

    The antioxidative effect of fullerenes C(60) and C(70) was examined by measuring the inhibition of methyl linoleate (MeL) peroxidation in toluene initiated by 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN). The fullerenes retarded the formation of MeL hydroperoxides and lowered the rate of propagation. The reaction rates of fullerenes with AMVN-derived peroxyl radicals were much higher than that of MeL. These results indicate that fullerenes can act as retarders of lipid peroxidation, though their activity is low compared with that of ?-tocopherol. PMID:22232272

  12. Immobilization of [60]fullerene on silicon surfaces through a calix[8]arene layer

    SciTech Connect

    Busolo, Filippo; Silvestrini, Simone; Maggini, Michele; Armelao, Lidia

    2013-10-28

    In this work, we report the functionalization of flat Si(100) surfaces with a calix[8]arene derivative through a thermal hydrosilylation process, followed by docking with [60]fullerene. Chemical grafting of calix[8]arene on silicon substrates was evaluated by X-ray photoelectron spectroscopy, whereas host-guest immobilization of fullerene was demonstrated by atomic force microscopy and sessile drop water contact angle measurements. Surface topographical variations, modelled on the basis of calix[8]arene and [60]fullerene geometrical parameters, are consistent with the observed morphological features relative to surface functionalization and to non-covalent immobilization of [60]fullerene.

  13. Synthesis of Fullerenes in Low Pressure Benzene/Oxygen Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Hebgen, Peter; Howard, Jack B.

    1999-01-01

    The interest in fullerenes is strongly increasing since their discovery by Kroto et al. in 1985 as products of the evaporation of carbon into inert gas at low pressure. Due to their all carbon closed-shell structure, fullerenes have many exceptional physical and chemical properties and a large potential for applications such as superconductors, sensors, catalysts, optical and electronic devices, polymers, high energy fuels, and biological and medical materials. This list is still growing, because the research on fullerenes is still at an early stage. Fullerenes can be formed not only in a system containing only carbon and an inert gas, but also in premixed hydrocarbon flames under reduced pressure and fuel rich conditions. The highest yields of fullerenes in flames are obtained under conditions of substantial soot formation. There is a need for more information on the yields of fullerenes under different conditions in order to understand the mechanisms of their formation and to enable the design of practical combustion systems for large-scale fullerene production. Little work has been reported on the formation of fullerenes in diffusion flames. In order to explore the yields of fullerenes and the effect of low pressure in diffusion flames, therefore we constructed and used a low pressure diffusion flame burner in this study.

  14. Effect of fullerene containing lubricants on wear resistance of machine components in boundary lubrication

    NASA Astrophysics Data System (ADS)

    Titov, Andriy

    Fullerenes, a new form of carbon nanomaterials, possess unique physical and mechanical properties that make their use as additives to liquid lubricants potentially beneficial. The goal of this study was to investigate the effect of fullerene containing lubricants on wear resistance of steel-bronze couples operating under boundary lubrication conditions. A mathematical model of deformed asperity contact was built to calculate real contact area and real contact pressure. Computer controlled wear friction testing methodology and equipment were designed, developed and implemented for obtaining reliable and objective experimental data. In addition, optical and scanning electron microscopy and standard surface texture analysis were employed. Heavy duty motor oil SAE 10 was modified by admixing fullerenes C60, a fullerene mixture of C60 and C70, fullerene containing soot, and graphite powder. The experiments showed that all of the selected fullerene additives dissolved in liquid lubricants reduce wear of the tested materials. In addition, it was found that despite improvements in wear resistance, the selected modified lubricants did not significantly change friction characteristics. Improvement of wear resistance of contact surfaces operating with fullerene modified lubricants can be explained by the presence of fullerenes in real contact while the liquid lubricant is squeezed out. Fullerenes are considered to function as minute hard particles that do not break down under applied normal force, and tend to separate direct contact of functional surfaces of selected materials.

  15. Effect of pulse-modulated microwaves on fullerene ion production with electron cyclotron resonance ion source.

    PubMed

    Asaji, T; Uchida, T; Minezaki, H; Oshima, K; Racz, R; Muramatsu, M; Biri, S; Kitagawa, A; Kato, Y; Yoshida, Y

    2012-02-01

    Fullerene plasmas generated by pulse-modulated microwaves have been investigated under typical conditions at the Bio-Nano electron cyclotron resonance ion source. The effect of the pulse modulation is distinct from that of simply structured gases, and then the density of the fullerene plasmas increased as decreasing the duty ratio. The density for a pulse width of 10 ?s at the period of 100 ?s is 1.34 times higher than that for CW mode. We have studied the responses of fullerene and argon plasmas to pulsed microwaves. After the turnoff of microwave power, fullerene plasmas lasted ?30 times longer than argon plasmas. PMID:22380150

  16. Controlling Exciton Diffusion and Fullerene Distribution in Photovoltaic Blends by Side Chain Modification

    PubMed Central

    2015-01-01

    The influence of crystallinity on exciton diffusion and fullerene distribution was investigated by blending amorphous and semicrystalline copolymers. We measured exciton diffusion and fluorescence quenching in such blends by dispersing fullerene molecules into them. We find that the diffusion length is more than two times higher in the semicrystalline copolymer than in the amorphous copolymer. We also find that fullerene preferentially mixes into disordered regions of the polymer film. This shows that relatively small differences in molecular structure are important for exciton diffusion and fullerene distribution. PMID:26267202

  17. Ultrafast processes of photoinduced charge and energy transfer in nanostructural fullerene-metal films

    SciTech Connect

    Chekalin, S. V.

    2006-11-15

    The primary stages of photoinduced processes in tin-doped C{sub 60} fullerene films have been studied using a femtosecond pump-probe technique with 150-fs laser excitation pulses ({lambda} = 400 nm) and differential transmission and reflection probing in the 1100-1700 nm range. The relaxation dynamics strongly depends both on the metal-to-fullerene ratio in the film and on the mutual distribution (packing) of components in the nanocomposite material. The observed response signal dynamics is related to features in the charge carrier generation, energy transfer between fullerene molecules, and charge transport between metal and fullerene.

  18. Many-Electron Response of Gas-Phase Fullerene Materials to Ultraviolet and Soft X-ray Photons

    NASA Astrophysics Data System (ADS)

    Chakraborty, Himadri S.; Magrakvelidze, Maia

    2015-06-01

    This article briefly reviews primary theoretical methods employed from the beginning of the century to predict the response of empty fullerenes, fullerenes endohedrally confining varieties of atoms, and few-layer fullerene nanoonions to the external electromagnetic radiations from ultraviolet to soft x-ray frequencies. Comparisons with available measurements are shown wherever possible and the success of the time-dependent local density approximation (TDLDA) method is predominantly emphasized. For the ionization process, various effects of the coherence, such as, the plasmon resonances, atom-fullerene dynamical hybridization, many-body correlations based on the interchannel coupling in the continuum, and Auger-intercoulombic hybrid multicenter decays of innershell holes are discussed. Finally, a broad outlook is presented that includes attosecond physics with fullerene materials, photoresponse of non-spherical fullerenes as well as fullerenes with off-centered confinements, the bare ion-impact ionization of fullerenes, and explorations beyond spherical systems to cylindrical carbon-nanotubes.

  19. Plasma Polymerization for Protein Patterning: Reversible Formation with Fullerene Modification

    NASA Astrophysics Data System (ADS)

    Takahashi, Hayato; Murata, Naoya; Muguruma, Hitoshi

    Partial plasma polymerization for coexistence of hydrophobic/hydrophilic area in several ten micrometer size is the typical technique for protein patterning. A hydrophobic hexamethyldisiloxane plasma-polymerized film (HMDS PPF) was deposited on a glass substrate and this surface was partially modified by subsequent nitrogen plasma treatment (hydrophilic surface, HMDS-N PPF) with a patterned shadow mask. An antibody protein (F(ab')2 fragment of anti-human immunoglobulin G) was selectively adsorbed onto the HMDS-N area and was not adsorbed onto the HMDS area. Distinct 80× 80µm2 square spots surrounded by a non-protein adsorbed 80µm-wide grid were observed. Then, when the protein modified by fullerene was used, the reversible patterning was obtained. This indicated that the modification by fullerene changed the hydrophilic nature of F(ab')2 protein to hydrophobic one, as a result, the modified protein was selectively adsorbed onto hydrophobic area.

  20. Synthesis and Atropisomerism of Cascaded Tetraphenylporphyrin-[60]Fullerene Hybrids.

    PubMed

    Schlundt, Sebastian; Bauer, Walter; Hirsch, Andreas

    2015-08-24

    Flexible, linked dendritic tetraphenylporphyrin (TPP)-fullerene hybrids were synthesized. They were designed to gain insight into and mimic the primary events in the natural photosynthetic reaction center. These multiporphyrin moieties are based on a light-harvesting concept. Moreover, they incorporate multiple redox components aligned along a redox gradient. Newkome-type dendrons were added to these TPP-fullerene hybrids. In principle they can mediate pH-dependent water solubility, which, however, could not be observed in this case. A protecting-group strategy using tert-butyldiphenylsilyl groups allows convergent synthesis of the dendritic compounds. The dendritic multiporphyrins were synthesized separately and can be used as individual building blocks. Atropisomerism was observed in the dendritic compounds, and single atropisomers could be assigned to the corresponding peaks of a characteristic pattern in the NMR spectra. Deprotection of the Newkome-type dendrons was shown to be feasible under mild conditions that leave the redox gradient intact. PMID:26235308

  1. Interface engineering for efficient fullerene-free organic solar cells

    SciTech Connect

    Shivanna, Ravichandran; Narayan, K. S. E-mail: narayan@jncasr.ac.in; Rajaram, Sridhar E-mail: narayan@jncasr.ac.in

    2015-03-23

    We demonstrate the role of zinc oxide (ZnO) morphology and addition of an acceptor interlayer to achieve high efficiency fullerene-free bulk heterojunction inverted organic solar cells. Nanopatterning of the ZnO buffer layer enhances the effective light absorption in the active layer, and the insertion of a twisted perylene acceptor layer planarizes and decreases the electron extraction barrier. Along with an increase in current homogeneity, the reduced work function difference and selective transport of electrons prevent the accumulation of charges and decrease the electron-hole recombination at the interface. These factors enable an overall increase of efficiency to 4.6%, which is significant for a fullerene-free solution-processed organic solar cell.

  2. Fullerene peapods: In-situ conductivity study during synthesis

    NASA Astrophysics Data System (ADS)

    You, Young Gyu; Kim, Sung Won; Uhm, Tae Woo; Jhang, Sung Ho; Park, Yung Woo

    2014-06-01

    We report in-situ measurement of the conductivity during the synthesis of C60-filled single-walled carbon nanotubes (SWNTs), so-called fullerene peapods. The synthesis was performed in a sealed quartz tube at 773 K by using the sublimation of C60 into the hollow space of the SWNTs. The change in the resistance in the SWNT buckypaper was monitored during the C60-filling process, and the temperature dependence of the resistance was compared to that for empty SWNTs and fullerene peapods. The SWNT networks became more metallic due to the encapsulation of C60, and a reduced temperature dependence of the resistivity was observed in the peapods, with an overall decrease in the resistivity. The interaction between the SWNT and C60 molecules, changing the electronic properties of SWNTs, can provide a way to functionalize the SWNTs.

  3. Photoabsorption spectrum of the Xe@C60 endohedral fullerene

    NASA Astrophysics Data System (ADS)

    Chen, Zhifan; Msezane, A. Z.

    2012-07-01

    Photoabsorption spectrum of the Xe@C60 endohedral fullerene has been studied using the time-dependent-density-functional-theory (TDDFT), which represents the dynamical polarizability of an interacting electron system by an off-diagonal matrix element of the resolvent of the Liouvillian superoperator and solves the problem with the Lanczos algorithm. The method has been tested with the photoabsorption spectra for the free Xe atom and C60 fullerene. The result of the Xe atom encapsulated inside C60 confirms the three main peaks observed in the recent measurement in the energy region of the Xe 4 d giant resonance and indicates the possibility that the Auger decay of the Xe+ has been greatly suppressed if the ion is encapsulated inside C60. It is suggested to use the current theoretical result around 22 eV to check this possibility.

  4. Recombination in polymer-fullerene bulk heterojunction solar cells

    SciTech Connect

    Cowan, Sarah; Roy, Anshuman; Heeger, Alan

    2010-12-16

    Recombination of photogenerated charge carriers in polymer bulk heterojunction (BHJ) solar cells reduces the short circuit current (J{sub sc} ) and the fill factor (FF). Identifying the mechanism of recombination is, therefore, fundamentally important for increasing the power conversion efficiency. Light intensity and temperature-dependent current-voltage measurements on polymer BHJ cells made from a variety of different semiconducting polymers and fullerenes show that the recombination kinetics are voltage dependent and evolve from first-order recombination at short circuit to bimolecular recombination at open circuit as a result of increasing the voltage-dependent charge carrier density in the cell. The missing 0.3 V inferred from comparison of the band gaps of the bulk heterojunction materials and the measured open-circuit voltage at room-temperature results from the temperature dependence of the quasi-Fermi levels in the polymer and fullerene domainsa conclusion based on the fundamental statistics of fermions.

  5. Thermal Isomerizations of Diethynyl Cyclobutadienes and Implications for Fullerene Formation.

    PubMed

    Esselman, Brian J; Emmert, Frank L; Wiederhold, Andrew J; Thompson, Stephanie J; Slipchenko, Lyudmila V; McMahon, Robert J

    2015-12-01

    The mechanism by which carbon condenses to form PAHs or fullerenes is a problem that has garnered considerable theoretical and experimental attention. The ring-coalescence and annealing model for the formation of C60 involves a [2 + 2] cycloaddition reaction of a cyclopolyyne to form a tetraalkynyl cyclobuta-1,3-diene intermediate, followed by a Bergman cycloaromatization reaction of the enediyne moiety. Intramolecular trapping of the incipient p-benzyne diradical across a diyne moiety of the macrocyclic ring affords an aromatic ring that must undergo further intramolecular reactions via polyradical intermediates to produce a condensed graphitic structure or fullerene. Computational studies of a model system for the intriguing tetraalkynylcyclobuta-1,3-diene intermediate, however, reveal that the corresponding p-benzyne diradical lies in a shallow minimum with a very low barrier to ring opening to cyclooctadienediyne. This pathway has not been previously considered in the mechanism for carbon condensation. PMID:26509879

  6. Influence of Substrate on Crystallization in Polythiophene/fullerene Blends

    SciTech Connect

    C He; D Germack; J Kline; D Delongchamp; D Fischer; C Snyder; M Toney; J Kushmerick; L Richter

    2011-12-31

    The nanoscale morphology of the active layer in organic, bulk heterojunction (BHJ) solar cells is crucial to device performance. Often a combination of casting conditions and post deposition thermal treatment is used to optimize the morphology. In general, the development of microscopic crystals is deleterious, as the exciton diffusion length is {approx}10 nm. We find that the microscopic crystallization behavior in polythiophene/fullerene blends is strongly influenced by the substrate on which the BHJ is cast. With a silicon oxide substrate, the crystal nucleation density is high and significant crystallization occurs at a temperature of 140 C. On more hydrophobic substrates, significantly higher temperatures are required for observable crystallization. This difference is attributed to the interfacial segregation of the PCBM, controlled by the substrate surface energy. The substrate dependence of crystallization has significant implications on the fullerene crystal growth mechanisms and practical implications for device studies.

  7. Back bombardment for dispenser and lanthanum hexaboride cathodes

    NASA Astrophysics Data System (ADS)

    Bakr, Mahmoud; Kinjo, R.; Choi, Y. W.; Omer, M.; Yoshida, K.; Ueda, S.; Takasaki, M.; Ishida, K.; Kimura, N.; Sonobe, T.; Kii, T.; Masuda, K.; Ohgaki, H.; Zen, H.

    2011-06-01

    The back bombardment (BB) effect limits wide usage of thermionic rf guns. The BB effect induces not only ramping-up of a cathodes temperature and beam current, but also degradation of cavity voltage and beam energy during a macropulse. This paper presents a comparison of the BB effect for the case of dispenser tungsten-base (DC) and lanthanum hexaboride (LaB6) thermionic rf gun cathodes. For each, particle simulation codes are used to simulate the BB effect and electron beam dynamics in a thermionic rf gun cathode. A semiempirical equation is also used to investigate the stopping range and deposited heat power of BB electrons in the cathode material. A numerical simulation method is used to calculate the change of the cathode temperature and current density during a single macropulse. This is done by solving two differential equations for the rf gun cavity equivalent circuit and one-dimensional thermal diffusion equation. High electron emission and small beam size are required for generation of a high-brightness electron beam, and so in this work the emission properties of the cathode are taken into account. Simulations of the BB effect show that, for a pulse of 6?s duration, the DC cathode experiences a large change in the temperature compared with LaB6, and a change in current density 6 times higher. Validation of the simulation results is performed using experimental data for beam current beyond the gun exit. The experimental data is well reproduced using the simulation method.

  8. Evolution of Titan's atmosphere during the Late Heavy Bombardment

    NASA Astrophysics Data System (ADS)

    Marounina, Nadejda; Tobie, Gabriel; Carpy, Sabrina; Monteux, Julien; Charnay, Benjamin; Grasset, Olivier

    2015-09-01

    The mass and composition of Titan's massive atmosphere, which is dominated by N2 and CH4 at present, have probably varied all along its history owing to a combination of exogenous and endogenous processes. In the present study, we investigate its fate during the Late Heavy Bombardment (LHB) by modeling the competitive loss and supply of volatiles by cometary impacts and their consequences on the atmospheric balance. For surface albedos ranging between 0.1 and 0.7, we examine the emergence of an atmosphere during the LHB as well as the evolution of a primitive atmosphere with various masses and compositions prior to this event, accounting for impact-induced crustal NH3-N2 conversion and subsequent outgassing as well as impact-induced atmospheric erosion. By considering an impactor population characteristic of the LHB, we show that the generation of a N2-rich atmosphere with a mass equivalent to the present-day one requires ammonia mass fraction of 2-5%, depending on surface albedos, in an icy layer of at least 50 km below the surface, implying an undifferentiated interior at the time of LHB. Except for high surface albedos (AS ⩾ 0.7) where most of the released N2 remain frozen at the surface, our calculations indicate that the high-velocity impacts led to a strong atmospheric erosion. For a differentiated Titan with a thin ammonia-enriched crust (⩽5 km) and AS < 0.6 , any atmosphere preexisting before the LHB should be more than 5 times more massive than at present, in order to sustain an atmosphere equivalent to the present-day one. This implies that either a massive atmosphere was formed on Titan during its accretion or that the nitrogen-rich atmosphere was generated after the LHB.

  9. Dual growth modes in ion bombarded Si surfaces

    SciTech Connect

    Dhillon, Prabhjeet Kaur; Sarkar, Subhendu

    2012-06-05

    Morphological studies were done on Si (001) surfaces after rastering them with a 1 keV O{sub 2}{sup +} ion beam at an angle. The resulting mounded morphology was studied using atomic force microscopy (AFM) measurements. The roughness at different length scales were further extracted and quantified from AFM measurements using scaling analysis. Results indicate two growth regimes of the evolving surface which were evident from the power spectral density (PSD) and interface width analysis of the eroded surfaces. Initially the growth is unstable followed by a stable regime of the nanostructures evolved after about 35 minutes of erosion. Temporal studies done on these surfaces show the onset of shadowing at higher sputtering times thus indicating the breakdown of the growth model at these times.

  10. SIMS depth profile study using metal cluster complex ion bombardment

    NASA Astrophysics Data System (ADS)

    Tomita, M.; Kinno, T.; Koike, M.; Tanaka, H.; Takeno, S.; Fujiwara, Y.; Kondou, K.; Teranishi, Y.; Nonaka, H.; Fujimoto, T.; Kurokawa, A.; Ichimura, S.

    2007-05-01

    SIMS depth profiles using a metal cluster complex ion of Ir4 (CO)7+were studied. An unusual increase of the sputtering yield under the condition of small incident angle may be attributed to the suppression of taking oxygen from flooding O2 by the formation of a carbon cover-layer derived from Ir4 (CO)7+ion. Even though the roughness of the sputtered surface is small, the depth resolution was not improved by decreasing the cluster ion energy to less than 5 keV, because the carbon cover-layer prevents the formation of surface oxide that buffers atomic mixing. To overcome this issue, it will be necessary to eliminate carbon from the cluster ion.

  11. Photoabsorption spectra of Xe atoms encapsulated inside fullerenes

    NASA Astrophysics Data System (ADS)

    Chen, Zhifan; Msezane, Alfred Z.

    2015-03-01

    The photoabsorption spectra of Xe atoms encapsulated inside the C180 and C240 have been investigated using the time-dependent density-functional theory (TDDFT) and compared with the result of our short range spherical well. The calculations are performed in the energy region of the Xe 4 d giant resonance and assumed the central location of the Xe atom inside the fullerenes. The Xe-C180 and Xe-C240 binding energies along the high symmetry direction, the z axis have been evaluated as well. The obtained curves show the possibility of other Xe positions. The main features of the confinement resonances for the Xe atoms in the center of the C180 and C240 may be estimated by the formula E(eV) = 67.55 + (12.25 n/2 r)2, where r is the radius in of the fullerene, n is the integer number 2, 3, 4, 5, ..., and E (eV) is the location of a confinement peak. The calculations indicate that if the radius of a fullerene equals an integer (?2) the half wave length of the photoelectron, then at this photon energy we may observe a confinement peak. The photoabsorption spectra of Xe atoms encaged in the center of the C58, C56 and C54 have also been studied. The results demonstrate that, except for the Xe atom inside C58, which has similar confinement resonances as those of the Xe atom inside C60, the Xe atoms inside C54 and C56 have completely different spectra. It is concluded that the quantum confinement resonances will be destroyed if the shape of the fullerene is deformed significantly from a sphere.

  12. Single or functionalized fullerenes interacting with heme group

    SciTech Connect

    Costa, Wallison Chaves; Diniz, Eduardo Moraes

    2014-09-15

    The heme group is responsible for iron transportation through the bloodstream, where iron participates in redox reactions, electron transfer, gases detection etc. The efficiency of such processes can be reduced if the whole heme molecule or even the iron is somehow altered from its original oxidation state, which can be caused by interactions with nanoparticles as fullerenes. To verify how such particles alter the geometry and electronic structure of heme molecule, here we report first principles calculations based on density functional theory of heme group interacting with single C{sub 60} fullerene or with C{sub 60} functionalized with small functional groups (−CH{sub 3}, −COOH, −NH{sub 2}, −OH). The calculations shown that the system heme + nanoparticle has a different spin state in comparison with heme group if the fullerene is functionalized. Also a functional group can provide a stronger binding between nanoparticle and heme molecule or inhibit the chemical bonding in comparison with single fullerene results. In addition heme molecule loses electrons to the nanoparticles and some systems exhibited a geometry distortion in heme group, depending on the binding energy. Furthermore, one find that such nanoparticles induce a formation of spin up states in heme group. Moreover, there exist modifications in density of states near the Fermi energy. Although of such changes in heme electronic structure and geometry, the iron atom remains in the heme group with the same oxidation state, so that processes that involve the iron might not be affected, only those that depend on the whole heme molecule.

  13. Top-down formation of fullerenes in the interstellar medium

    NASA Astrophysics Data System (ADS)

    Bern, O.; Montillaud, J.; Joblin, C.

    2015-05-01

    Fullerenes have recently been detected in various circumstellar and interstellar environments, raising the question of their formation pathway. It has been proposed that they can form at the low densities found in the interstellar medium by the photo-chemical processing of large polycyclic aromatic hydrocarbons (PAHs). Following our previous work on the evolution of PAHs in the NGC 7023 reflection nebula, we evaluate, using photochemical modelling, the possibility that the PAH C66H20 (i.e. circumovalene) can lead to the formation of the C60 fullerene upon irradiation by ultraviolet photons. The chemical pathway involves full dehydrogenation of C66H20, folding into a floppy closed cage and shrinking of the cage by loss of C2 units until it reaches the symmetric C60 molecule. At 10'' from the illuminating star and with realistic molecular parameters, the model predicts that 100% of C66H20 is converted into C60 in ~105 yr, a timescale comparable to the age of the nebula. Shrinking appears to be the kinetically limiting step of the whole process. Hence, PAHs larger than C66H20 are unlikely to contribute significantly to the formation of C60, while PAHs containing between 60 and 66 C atoms should contribute to the formation of C60 with shorter timescales, and PAHs containing fewer than 60 C atoms will be destroyed. Assuming a classical size distribution for the PAH precursors, our model predicts that absolute abundances of C60 are up to several 10-4 of the elemental carbon, that is, less than a percent of the typical interstellar PAH abundance, which is consistent with observational studies. According to our model, once formed, C60 can survive much longer (> 107 yr for radiation fields below G0 = 104) than other fullerenes because of the remarkable stability of the C60 molecule at high internal energies. Hence, a natural consequence is that C60 is more abundant than other fullerenes in highly irradiated environments.

  14. Design, synthesis and testing of fullerene-functionalized devices and machines

    NASA Astrophysics Data System (ADS)

    Shirai, Yasuhiro

    Herein is described the design, synthesis and testing of molecules that contain fullerenes as essential parts. In chapter 1, a series of multiple fullerene terminated oligo(p-phenylene ethynylene) (OPE) hybrid compounds was synthesized through a newly developed in situ ethynylation method. Electronic and optical interactions between the fullerenes and the OPE backbones were investigated by UV/Vis spectroscopy, cyclic voltammetry (CV), and differential optical Kerr effect (DOKE) experiment. Enhanced nonlinear optical (NLO) performance of some of the fullerene-OPE hybrids is presumably due to the occurrence of periconjugation and/or charge transfer effects between the fullerene and OPE moieties in the excited state. This result indicates that the use of such fullerene-derivatized conjugated oligomers aids the quest for NLO devices. In chapter 2, fullerene-wheeled single molecular nanomachines, namely nanocars and nanotrucks, are presented. These nanovehicles are composed of spherical fullerene wheels, freely rotating alkynyl axles, and a molecular chassis. The use of spherical wheels based on C60 and freely rotating axles based on alkynes permits directed nanoscale rolling of the molecular structure on gold surfaces. The rolling motion observed by scanning tunneling microscope (STM) resembles the same motion performed by macroscopic entities in which rolling occurs perpendicular to the axles. This study underscores the ability to control directionality of motion in molecular-sized nanostructures through precise molecular design and synthesis. Chapter 3 describes that the seemingly simple and widely employed approach to self-assembly of fullerene-derivatives on gold surfaces can be complicated due to multilayer formation and head-to-tail assemblies resulting from the strong fullerene-fullerene and fullerene-gold interactions. These anomalies were not examined in detail in previous studies on fullerene self-assembled monolayers (SAMs) but were clearly detected in the present work using surface characterization techniques including ellipsometry, CV, and X-ray photoelectron spectroscopy (XPS). This study specifically addresses the need to properly characterize and control fullerene-thiol assemblies on gold before evaluating subsequent device performances. Finally, chapter 4 describes the synthesis and testing of a motorized nanocar. Kinetics studies in solution show that the motor indeed rotates upon irradiation with 365 nm light, and the fullerene-free carborane wheel system is an essential design feature for motor operation.

  15. Is the Use of Fullerene in Photodynamic Therapy Effective for Atherosclerosis?

    SciTech Connect

    Nitta, Norihisa Seko, Ayumi; Sonoda, Akinaga; Ohta, Shinichi; Tanaka, Toyohiko; Takahashi, Masashi; Murata, Kiyoshi; Takemura, Shizuki; Sakamoto, Tsutomu; Tabata, Yasuhiko

    2008-03-15

    The purpose of this study was to evaluate Fullerene as a therapeutic photosensitizer in the treatment of atherosclerosis. An atherosclerotic experimental rabbit model was prepared by causing intimal injury to bilateral external iliac arteries using balloon expansion. In four atherosclerotic rabbits and one normal rabbit, polyethylene glycol-modified Fullerene (Fullerene-PEG) was infused into the left external iliac artery and illuminated by light emitting diode (LED), while the right external iliac artery was only illuminated by LED. Two weeks later, the histological findings for each iliac artery were evaluated quantitatively and comparisons were made among atherosclerotic Fullerene+LED artery (n = 4), atherosclerotic light artery (n = 4), normal Fullerene+LED artery (n = 1), and normal light artery (n = 1). An additional two atherosclerotic rabbits were studied by fluorescence microscopy, after Fullerene-PEG-Cy5 complex infusion into the left external iliac artery, for evaluation of Fullerene-PEG incorporated within the atherosclerotic lesions. The degree of atherosclerosis in the atherosclerotic Fullerene+LED artery was significantly (p < 0.05) more severe than that in the atherosclerotic LED artery. No pathological change was observed in normal Fullerene+LED and LED arteries. In addition, strong accumulation of Fullerene-PEG-Cy5 complex within the plaque of the left iliac artery of the two rabbits was demonstrated, in contrast to no accumulation in the right iliac artery. We conclude that infusion of a high concentration of Fullerene-PEG followed by photo-illumination resulted not in a suppression of atherosclerosis but in a progression of atherosclerosis in experimental rabbit models. However, this intervention showed no adverse effects on the normal iliac artery.

  16. Thermal Transport in Fullerene Derivatives Using Molecular Dynamics Simulations

    PubMed Central

    Chen, Liang; Wang, Xiaojia; Kumar, Satish

    2015-01-01

    In order to study the effects of alkyl chain on the thermal properties of fullerene derivatives, we perform molecular dynamics (MD) simulations to predict the thermal conductivity of fullerene (C60) and its derivative phenyl-C61-butyric acid methyl ester (PCBM). The results of non-equilibrium MD simulations show a length-dependent thermal conductivity for C60 but not for PCBM. The thermal conductivity of C60, obtained from the linear extrapolation of inverse conductivity vs. inverse length curve, is 0.2??W?m?1?K?1 at room temperature, while the thermal conductivity of PCBM saturates at ~0.075??W?m?1?K?1 around 20?nm. The different length-dependence behavior of thermal conductivity indicates that the long-wavelength and low-frequency phonons have large contribution to the thermal conduction in C60. The decrease in thermal conductivity of fullerene derivatives can be attributed to the reduction in group velocities, the decrease of the frequency range of acoustic phonons, and the strong scattering of low-frequency phonons with the alkyl chains due to the significant mismatch of vibrational density of states in low frequency regime between buckyball and alkyl chains in PCBM. PMID:26238607

  17. The Environmental Fate of C60 Fullerenes: A Holistic Approach

    NASA Astrophysics Data System (ADS)

    Schreiner, K. M.; Filley, T. R.; Blanchette, R. A.; Jafvert, C.; Bolskar, R.

    2007-12-01

    The manufacture and use of carbon-based nanoparticles, for which C60 fullerenes can be considered a proxy, has grown exponentially in the past decade, and nanotechnology is now a multi-billion dollar industry, spanning disciplines such as cosmetics, biotechnology, and agriculture. Despite this, almost nothing is known of the fate of these compounds in the environment. Based upon the strong radical scavenging properties of many of these substances there are a variety of microbial and photochemical-mediated oxidative fates that will transform the physicochemical properties and control the residence time of these compounds in nature. It is essential that these fates, as well as the fates of the products of the degradation of carbon nanoparticles, are known. For instance, conversion of C60 fullerenes to hydroxylated or carboxylated analogs will shift the manner in which they partition between soils and sediments and water as well as how they interact with cell membranes. This paper combines our findings on the microbial activity of C60 fullerenes, one of the most common types of manufactured carbon nanoparticles, along with recent literature to develop potential chemical decay trajectories in oxidative environmental settings. We show what is known about the environmental fate of this type of nanomaterial and also areas where further research is needed.

  18. Thermal Transport in Fullerene Derivatives Using Molecular Dynamics Simulations

    NASA Astrophysics Data System (ADS)

    Chen, Liang; Wang, Xiaojia; Kumar, Satish

    2015-08-01

    In order to study the effects of alkyl chain on the thermal properties of fullerene derivatives, we perform molecular dynamics (MD) simulations to predict the thermal conductivity of fullerene (C60) and its derivative phenyl-C61-butyric acid methyl ester (PCBM). The results of non-equilibrium MD simulations show a length-dependent thermal conductivity for C60 but not for PCBM. The thermal conductivity of C60, obtained from the linear extrapolation of inverse conductivity vs. inverse length curve, is 0.2??W?m-1?K-1 at room temperature, while the thermal conductivity of PCBM saturates at ~0.075??W?m-1?K-1 around 20?nm. The different length-dependence behavior of thermal conductivity indicates that the long-wavelength and low-frequency phonons have large contribution to the thermal conduction in C60. The decrease in thermal conductivity of fullerene derivatives can be attributed to the reduction in group velocities, the decrease of the frequency range of acoustic phonons, and the strong scattering of low-frequency phonons with the alkyl chains due to the significant mismatch of vibrational density of states in low frequency regime between buckyball and alkyl chains in PCBM.

  19. Synthesis and antioxidant activity of [60]fullerene-BHT conjugates.

    PubMed

    Enes, Roger F; Tom, Augusto C; Cavaleiro, Jos A S; Amorati, Riccardo; Fumo, Maria Grazia; Pedulli, Gian Franco; Valgimigli, Luca

    2006-06-01

    Fullerene derivatives incorporating one or two 3,5-di-tert-butyl-4-hydroxyphenyl groups were synthesized by 1,3-dipolar cycloaddition of azomethine ylides to C(60). The O-H bond dissociation enthalpies (BDEs) of these compounds were estimated by studying, by means of EPR spectroscopy, the equilibration of each of these phenols and 2,6-di-tert-butyl-4-methylphenol (BHT) with the corresponding phenoxyl radicals. The antioxidant activity of the investigated phenols was also determined by measuring the rate constants for their reaction with peroxyl radicals in controlled autoxidation experiments and compared to that recorded under identical experimental settings for [60]fullerene itself and unlinked BHT. The results indicate that linking of the BHT structure to C(60) does not substantially alter the thermochemistry and kinetics of its reaction with peroxyl radicals, but such adducts may behave as interesting bimodal radical scavengers. The inherent rate constant for trapping of peroxyl radicals by C(60) per se (k(inh)=3.1+/-1.1 x 10(2) m(-1) s(-1)) indicates that, contrary to previous reports, [60]fullerene is an extremely weak chain-breaking antioxidant. PMID:16534828

  20. The interaction of He{sup ?} with fullerenes

    SciTech Connect

    Mauracher, Andreas; Daxner, Matthias; Huber, Stefan E.; Postler, Johannes; Renzler, Michael; Denifl, Stephan; Scheier, Paul E-mail: andrew.ellis@le.ac.uk; Ellis, Andrew M. E-mail: andrew.ellis@le.ac.uk

    2015-03-14

    The effects of interactions between He{sup ?} and clusters of fullerenes in helium nanodroplets are described. Electron transfer from He{sup ?} to (C{sub 60}){sub n} and (C{sub 70}){sub n} clusters results in the formation of the corresponding fullerene cluster dianions. This unusual double electron transfer appears to be concerted and is most likely guided by electron correlation between the two very weakly bound outer electrons in He{sup ?}. We suggest a mechanism which involves long range electron transfer followed by the conversion of He{sup +}into He{sub 2}{sup +}, where formation of the HeHe bond in He{sub 2}{sup +} releases sufficient kinetic energy for the cation and the dianion to escape their Coulombic attraction. By analogy with the corresponding dications, the observation of a threshold size of n ? 5 for formation of both (C{sub 60}){sub n}{sup 2?} and (C{sub 70}){sub n}{sup 2?} is attributed to Coulomb explosion rather than an energetic constraint. We also find that smaller dianions can be observed if water is added as a co-dopant. Other aspects of He{sup ?} chemistry that are explored include its role in the formation of multiply charged fullerene cluster cations and the sensitivity of cluster dianion formation on the incident electron energy.

  1. Characterisation and determination of fullerenes: A critical review.

    PubMed

    Astefanei, Alina; Nez, Oscar; Galceran, Maria Teresa

    2015-07-01

    A prominent sector of nanotechnology is occupied by a class of carbon-based nanoparticles known as fullerenes. Fullerene particle size and shape impact in how easily these particles are transported into and throughout the environment and living tissues. Currently, there is a lack of adequate methodology for their size and shape characterisation, identification and quantitative detection in environmental and biological samples. The most commonly used methods for their size measurements (aggregation, size distribution, shape, etc.), the effect of sampling and sample treatment on these characteristics and the analytical methods proposed for their determination in complex matrices are discussed in this review. For the characterisation and analysis of fullerenes in real samples, different analytical techniques including microscopy, spectroscopy, flow field-flow fractionation, electrophoresis, light scattering, liquid chromatography and mass spectrometry have been reported. The existing limitations and knowledge gaps in the use of these techniques are discussed and the necessity to hyphenate complementary ones for the accurate characterisation, identification and quantitation of these nanoparticles is highlighted. PMID:26043086

  2. Inhibition of a thermophilic deoxyribonucleic acid polymerase by fullerene derivatives.

    PubMed

    Meng, Xianmei; Li, Bo; Chen, Zhe; Yao, Lu; Zhao, Dongxu; Yang, Xinlin; He, Min; Yu, Qun

    2007-06-01

    Enzyme inhibition by fullerene derivatives has attracted much attention. In this communication, effects of two water-solube fullerene derivatives, fullerol and trimalonic acid C60 (TMA C60) on polymerase chain reaction (PCR) were investigated by using PCR of beta-actin cDNA derived from HeLa cells as an experimental model. Both fullerol and TMA C60 were found to inhibit PCR in a dose-dependent manner. PCR was ultimately inhibited while the concentrations of each compound were not less than 0.01 mM. In contrast, mannitol exerted no effects on PCR while its concentration increased up to 2 mM. Compensation experiments with Thermus aquaticus (Taq) DNA polymerase revealed that both fullerol and TMA C60 inhibited the enzymatic activity of Taq DNA polymerase, and the inhibitory potency of TMA C60 was slightly greater than that of fullerol. Our data provides some novel aspects on the enzyme inhibiting activities of fullerene derivatives. PMID:17674810

  3. New fullerene-based mixed materials: Synthesis and characterization

    SciTech Connect

    McBranch, D.; Kohlman, R.; Klimov, V.; Grigorova, M.; Shi, X.; Smilowitz, L.; Mattes, B.R.; Wang, H.; Wudl, F.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors present results of broadband femtosecond transient absorption and broadband nanosecond optical limiting studies of C{sub 60} and derivatized C{sub 60}. They have investigated both solutions and solid-state mixed materials (sol-gel glass hosts doped with fullerene guests). They show that derivatized fullerenes provide enhanced solubility and processability, with a ground-state absorption extended into the infrared compared with C{sub 60}. They have extensively studied both the dynamic optical response and the excited-state absorption cross sections of solutions and solids for multiple wavelengths in the visible to near infrared. Wavelength-dependent studies show that the optical limiting response improves monotonically at longer wavelengths, demonstrating broadband limiting in all 6,6 mono-adducts and neat C{sub 60}. The authors report new approaches to processing sol-gel glass/fullerene composites to improve the optical limiting performance of solid-state materials to approach the response of solution limiters.

  4. Study of urological devices coated with fullerene-like nanoparticles.

    PubMed

    Goldbart, Ohad; Elianov, Olga; Shumalinsky, Dmitry; Lobik, Leonid; Cytron, Shmuel; Rosentsveig, Rita; Wagner, H Daniel; Tenne, Reshef

    2013-09-21

    Insertion of endoscopes and other medical devices into the human body are ubiquitous, especially among aged males. The applied force for the insertion/extraction of the device from the urethra must overcome endoscope-surface-human-tissue interactions. In daily practice a gel is applied on the endoscope surface, in order to facilitate its entry into the urethra, providing also for local anesthesia. In the present work, a new solid-state lubricant has been added to the gel, in order to reduce the metal-urethra interaction and alleviate the potential damage to the epithelial tissue. For that purpose, a urethra model was designed and fabricated, which allowed a quantitative assessment of the applied force for extraction of the endoscope from a soft polymer-based ring. It is shown that the addition of MoS2 nanoparticles with fullerene-like structure (IF-MoS2) and in particular rhenium-doped nanoparticles (Re:IF-MoS2) to Esracain gel applied on the metal-lead reduced the friction substantially. The Re:IF-MoS2 showed better results than the undoped fullerene-like nanoparticles and both performed better than the gel alone. The mechanism of friction reduction is attributed to fullerenes' ability to roll and act as a separator between the active parts of the model. PMID:23884307

  5. Fullerene derivatives as electron acceptors for organic photovoltaic cells.

    PubMed

    Mi, Dongbo; Kim, Ji-Hoon; Kim, Hee Un; Xu, Fei; Hwang, Do-Hoon

    2014-02-01

    Energy is currently one of the most important problems humankind faces. Depletion of traditional energy sources such as coal and oil results in the need to develop new ways to create, transport, and store electricity. In this regard, the sun, which can be considered as a giant nuclear fusion reactor, represents the most powerful source of energy available in our solar system. For photovoltaic cells to gain widespread acceptance as a source of clean and renewable energy, the cost per watt of solar energy must be decreased. Organic photovoltaic cells, developed in the past two decades, have potential as alternatives to traditional inorganic semiconductor photovoltaic cells, which suffer from high environmental pollution and energy consumption during production. Organic photovoltaic cells are composed of a blended film of a conjugated-polymer donor and a soluble fullerene-derivative acceptor sandwiched between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-coated indium tin oxide positive electrode and a low-work-function metal negative electrode. Considerable research efforts aim at designing and synthesizing novel fullerene derivatives as electron acceptors with up-raised lowest unoccupied molecular orbital energy, better light-harvesting properties, higher electron mobility, and better miscibility with the polymer donor for improving the power conversion efficiency of the organic photovoltaic cells. In this paper, we systematically review novel fullerene acceptors synthesized through chemical modification for enhancing the photovoltaic performance by increasing open-circuit voltage, short-circuit current, and fill factor, which determine the performance of organic photovoltaic cells. PMID:24749413

  6. Fullerene-bisadduct acceptors for polymer solar cells.

    PubMed

    Li, Yongfang

    2013-10-01

    Polymer solar cells (PSCs) have drawn great attention in recent years for their simple device structure, light weight, and low-cost fabrication in comparison with inorganic semiconductor solar cells. However, the power-conversion efficiency (PCE) of PSCs needs to be increased for their future application. The key issue for improving the PCE of PSCs is the design and synthesis of high-efficiency conjugated polymer donors and fullerene acceptors for the photovoltaic materials. For the acceptor materials, several fullerene-bisadduct acceptors with high LUMO energy levels have demonstrated excellent photovoltaic performance in PSCs with P3HT as a donor. In this Focus Review, recent progress in high-efficiency fullerene-bisadduct acceptors is discussed, including the bisadduct of PCBM, indene-C60 bisadduct (ICBA), indene-C70 bisadduct (IC70BA), DMPCBA, NCBA, and bisTOQC. The LUMO levels and photovoltaic performance of these bisadduct acceptors with P3HT as a donor are summarized and compared. In addition, the applications of an ICBA acceptor in new device structures and with other conjugated polymer donors than P3HT are also introduced and discussed. PMID:23853151

  7. Study of urological devices coated with fullerene-like nanoparticles

    NASA Astrophysics Data System (ADS)

    Goldbart, Ohad; Elianov, Olga; Shumalinsky, Dmitry; Lobik, Leonid; Cytron, Shmuel; Rosentsveig, Rita; Wagner, H. Daniel; Tenne, Reshef

    2013-08-01

    Insertion of endoscopes and other medical devices into the human body are ubiquitous, especially among aged males. The applied force for the insertion/extraction of the device from the urethra must overcome endoscope-surface-human-tissue interactions. In daily practice a gel is applied on the endoscope surface, in order to facilitate its entry into the urethra, providing also for local anesthesia. In the present work, a new solid-state lubricant has been added to the gel, in order to reduce the metal-urethra interaction and alleviate the potential damage to the epithelial tissue. For that purpose, a urethra model was designed and fabricated, which allowed a quantitative assessment of the applied force for extraction of the endoscope from a soft polymer-based ring. It is shown that the addition of MoS2 nanoparticles with fullerene-like structure (IF-MoS2) and in particular rhenium-doped nanoparticles (Re:IF-MoS2) to Esracain gel applied on the metal-lead reduced the friction substantially. The Re:IF-MoS2 showed better results than the undoped fullerene-like nanoparticles and both performed better than the gel alone. The mechanism of friction reduction is attributed to fullerenes' ability to roll and act as a separator between the active parts of the model.

  8. Compton Profiles of Silver with 662 keV ?-Rays

    NASA Astrophysics Data System (ADS)

    Chang, Chu-Nan; Lee, Syh-Bin; Chen, Chuhn-Chih

    1991-12-01

    The isotropic Compton profiles of Ag for two thicknesses, 2 mm and 4 mm, have been measured by means of 662 keV ?-rays from Cs137 source. A HpGe detector with resolution of 190 eV at 5.9 keV was used to detect the backward scattering photons. Comparison with the renormalized-free-atom model calculations was made, and the agreement between the experimental and the calculated values has been found to be good for the electron configuration 4d105s1.

  9. Chemistry of acenes, [60]fullerenes, cyclacenes and carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pramanik, Chandrani

    2011-12-01

    In the present work, we studied the chemistries of acenes, cyclacenes, [60]fullerenes and CNTs. Acenes are well known organic semiconductors. Pentacene is a benchmark organic semiconductor due to low HOMO-LUMO gap and high charge carrier mobilities in its thin film. Its poor solubility and instability, however, limit its utility and overall cost effectiveness. We successfully synthesized several sulfur-functionalized acene derivatives that overcome these problems. However, we also encountered difficulties to aromatize some of these derivatives. To circumvent these problems, we studied some new synthetic routes to sulfur-functionalized anthracenes, pentacenes and nonacenes. Additionally, the electronic properties of substituted acenes were compared using high level DFT calculations. According to our unrestricted DFT calculations, significant spin characters associated with thio-substituted nonacenes are likely the reason for their instabilities and difficult syntheses. Our UV-Vis-NIR studies reveal acene characteristics in acene quinones and hydroxyacenes that are dissolved in concentrated sulfuric acid. Cyclacenes may be useful precursors to synthesize SWNTs with uniform dimensions. We explored the supramolecular assembly of a bis[60]fullerene adduct of a 2,3,9,10-tetrasubstituted pentacene as a method to produce a [24]cyclacene framework. To that end, we synthesized the bis[60]fullerene adduct of 2,3,9,10-tetraiodomethyl-6,13-diphenylpentacene. The synthesis of a cyclacene framework via intermolecular cycloaddition of bis[60]fullerene adducts requires further study. According to our unrestricted broken symmetry calculations for different functionalized [n]cyclacenes, HOMO-LUMO gaps and spin characters are impacted by the presence and location of alkylthio and/or arylthio functional groups on the [n]cyclacene skeleton. [60]Fullerene is known to form polysultone and chlorinated derivatives when treated with fuming sulfuric acid (FSA) and chlorosulfonic acid (CSA), respectively, at room temperature. Based on our preliminary study, we predict that MWNTs react with boiling CSA and they are unreactive toward boiling FSA. The CSA treated MWNTs showed less bundling and broken tips in their AFM and TEM images. We studied the self-assembly of carboxylated-SWNTs and polystyrene latex (PSL) particles on different substrates. We believe that carboxylated-SWNTs have stronger interactions with amino or carboxy terminated PSL than unsubstituted PSL particles. According to our SEM analysis, self-assembly of the nanocomposites is moderately substrate dependent.

  10. Molecular dynamics simulation of bio-fullerene interfaces

    NASA Astrophysics Data System (ADS)

    Noon, William H.

    Molecular Dynamics (MD) simulations were employed to study the interaction of fullerene molecules in biological environments. Initial work considers the interaction of peptides with fullerene, where a fullerene specific antibody and a single-walled carbon nanotube (SWNT) wrapped by a peptide was simulated. Results reveal the interface between peptides and fullerene to be dominated by hydrophobic interactions. Also, pi-stacking interactions were a predominant recognition mode. Electrostatic forces primarily defined the shape of the complex around the fullerene. Another study involved the interaction of water with SWNT. Unexpectedly, water was observed to partition within the center of nanotubes. Furthermore, the water organizes into a hydrogen-bonded network that is dependent upon nanotube diameter. The phenomenon parallels the function of transmembrane proteins, and consequently, free energy calculations were completed to consider if nanotubes exhibited selective ion partitioning. Indeed, ions specifically favored certain nanotube indices and selectivity was dependent upon nanotube diameter and ion solvation structure. Much of this thesis analyzes the structure of sodium dodecyl sulfate (SDS) around SWNT. Initial results suggested that nanotubes were encased in a thick micelle that prohibited water from contacting the tube. However, later experimental data suggested a much more dynamic system and therefore new simulation techniques were developed to achieve an improved model. The new methodology was first developed by simulating the aggregation of a random mixture of SDS into micelles of experimentally expected sizes and structures. After successful testing, a random mixture was allowed to aggregate onto a nanotube. The results reveal a random monolayer exists around the tube, but the head groups and water molecules are much closer the tube, which accounts for the more dynamic fluorescence properties observed. Simple geometric modeling and recent fluorescence measurements are also considered to further support the improved model. Finally, the aggregation of polyethylene oxide (PEO) derived polymers around SWNT was completed. Results reveal a much weaker hydrophobic interaction with the tube and consequently much less of the tube is covered by polymer. The findings correlate well with fluorescence and protein adsorption experiments. The structure of the wrapping polymer is also considered, along with the effect of molecular weight.

  11. Conformationally Constrained Macrocyclic Diporphyrin-Fullerene Artificial Photosynthetic Reaction Center

    SciTech Connect

    Garg, Vikas; Kodis, Gerdenis; Chachisvilis, Mirianas; Hambourger, Michael; Moore, Ana L.; Moore, Thomas A.; Gust, Devens

    2011-02-14

    Photosynthetic reaction centers convert excitation energy from absorbed sunlight into chemical potential energy in the form of a charge-separated state. The rates of the electron transfer reactions necessary to achieve long-lived, high-energy charge-separated states with high quantum yields are determined in part by precise control of the electronic coupling among the chromophores, donors, and acceptors and of the reaction energetics. Successful artificial photosynthetic reaction centers for solar energy conversion have similar requirements. Control of electronic coupling in particular necessitates chemical linkages between active component moieties that both mediate coupling and restrict conformational mobility so that only spatial arrangements that promote favorable coupling are populated. Toward this end, we report the synthesis, structure, and photochemical properties of an artificial reaction center containing two porphyrin electron donor moieties and a fullerene electron acceptor in a macrocyclic arrangement involving a ring of 42 atoms. The two porphyrins are closely spaced, in an arrangement reminiscent of that of the special pair in bacterial reaction centers. The molecule is produced by an unusual cyclization reaction that yields mainly a product with C2 symmetry and trans-2 disubstitution at the fullerene. The macrocycle maintains a rigid, highly constrained structure that was determined by UV-vis spectroscopy, NMR, mass spectrometry, and molecular modeling at the semiempirical PM6 and DFT (B3LYP/6-31G**) levels. Transient absorption results for the macrocycle in 2-methyltetrahydrofuran reveal photoinduced electron transfer from the porphyrin first excited singlet state to the fullerene to form a P--C60--P charge separated state with a time constant of 1.1 ps. Photoinduced electron transfer to the fullerene excited singlet state to form the same charge-separated state has a time constant of 15 ps. The charge-separated state is formed with a quantum yield of essentially unity and has a lifetime of 2.7 ns. The ultrafast charge separation coupled with charge recombination that is over 2000 times slower is consistent with a very rigid molecular structure having a small reorganization energy for electron transfer, relative to related porphyrin-fullerene molecules.

  12. Theory and mitigation of electron back-bombardment in thermionic cathode radio frequency guns

    NASA Astrophysics Data System (ADS)

    Edelen, Jonathan Paul

    Photocathode RF guns are currently the standard for high- power, low-emittance beam generation in free-electron lasers. These devices require the use of high-power lasers (which are bulky and expensive to operate) and high-quantum-efficiency cathodes (which have limited lifetimes requiring frequent replacement). The use of RF-gated thermionic cathodes enables operation without a large drive laser and with long lifetimes. One major limitation of RF-gated thermionic cathodes is that electrons emitted late in the RF period will not gain enough energy to exit the gun before being accelerated back towards the cathode by the change in sign of the RF field. These electrons deposit their kinetic energy on the cathode surface in the form of heat, limiting the ability to control the output current from the cathode. This dissertation is aimed at understanding the fundamental design factors that drive the back-bombardment process and at exploring novel techniques to reduce its impact on a high-current system. This begins with the development of analytic models that predict the back-bombardment process in single-cell guns. These models are compared with simulation and with a measurement taken at a specific facility. This is followed by the development of analytic models that predict the effects of space-charge on back-bombardment. These models are compared with simulations. This is followed by an analysis of how the addition of multiple cells will impact the back-bombardment process. Finally, a two-frequency gun is studied for its ability to mitigate the back-bombardment process. This dissertation provides new insight on how the back-bombardment process scales as a function of the beam parameters and how space-charge affects this process. Additionally this dissertation shows how a second frequency can be used to mitigate the back-bombardment effect.

  13. Fullerene Nanoparticles Exhibit Greater Retention in Freshwater Sediment than in Model Porous Media

    EPA Science Inventory

    Increasing production and use of fullerene-based nanomaterials underscore the need to determine their mobility in environmental transport pathways and potential ecological exposures. This study investigated the transport of two fullerenes (i.e., aqu/C(60) and water-soluble C(60) ...

  14. 40 CFR 721.10267 - [5,6]Fullerene-C60-Ih.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances 721.10267 Fullerene-C60-Ih. (a) Chemical substance and significant new uses subject to reporting.(1) The chemical substance identified as Fullerene-C60-Ih (PMN P-09-54;CAS No. 99685-96-8) is...

  15. 40 CFR 721.10268 - [5,6]Fullerene-C70-D5h(6).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances 721.10268 Fullerene-C70-D5h(6). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as Fullerene-C70-D5h(6) (PMN P-09-55; CAS No....

  16. 40 CFR 721.10269 - [5,6]Fullerene-C84-D2.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances 721.10269 Fullerene-C84-D2. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as Fullerene-C84-D2 (PMN P-09-56; CAS No. 145809-19-4)...

  17. 40 CFR 721.10270 - [5,6]Fullerene-C84-D2d.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances 721.10270 Fullerene-C84-D2d. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as Fullerene-C84-D2d (PMN P-09-57; CAS No. 145809-20-7)...

  18. Pharmacological studies on fullerene (C60), a novel carbon allotrope, and its derivatives.

    PubMed

    Satoh, Mitsutoshi; Takayanagi, Issei

    2006-01-01

    Fullerene (C(60)), a condensed ring aromatic compound with extended pi systems, is a novel carbon allotrope. Because of its poor solubility in polar solvents, investigation of the biological and pharmacological properties of fullerene has been difficult. Recently, water-soluble fullerene derivatives have been synthesized, and we and others have found that they have potent and selective pharmacological effects on organs, cells, enzymes, and nucleic acids. In the presence of fullerene C(60) derivative (10(-5) M), endothelium-dependent relaxations induced by agonists in the vascular system were eliminated and acetylcholine-induced contractile response of smooth muscle was observed. Some investigators have reported free radical-scavenging activity and direct nitric oxide-quenching activity of fullerene derivatives. Knowledge of the chemical modifications, biological significance, and materials applications of functionalized fullerenes is growing rapidly; and these compounds are emerging as new tools in the field. The focus of this review is to introduce several pharmacological effects of fullerenes and to discuss the possible mechanisms of the pharmacological actions caused by previously synthesized fullerenes. PMID:16682790

  19. Solubilization of fullerene C60 in micellar solutions of different solubilizers.

    PubMed

    Torres, Vukosava Milic; Posa, Mihalj; Srdjenovic, Branislava; Simplcio, Ana Lusa

    2011-01-01

    Fullerene (C(60)), the third carbon allotrope, is a classical engineered material with the potential application in biomedicine. However, extremely high hydrophobicity of fullerene hampers its direct biomedical evaluation and application. In this work, we investigated the solubilization of fullerene using 9 different solubility enhancers: Tween 20, Tween 60, Tween 80, Triton X-100, PVP, polyoxyethylene (10) lauryl ether, n-dodecyl trimethylammonium chloride, myristyl trimethylammonium bromide and sodium dodecyl sulphate and evaluated its antioxidant activity in biorelevant media. The presence of C(60) entrapped in surfactant micelles was confirmed by UV/VIS spectrometry. The efficacy of each modifier was evaluated by chemometric analysis using experimental data for investigating the relationship between solubilization and particle size distribution. Hierarchical clustering and principal component analysis was applied and showed that non-ionic surfactants provide better solubilization efficacy (>85%). A correlation was established (r=0.975) between the degree of solubilization and the surfactant structure. This correlation may be used for prediction of C(60) solubilization with non-tested solubility modifiers. Since the main potential biomedical applications of fullerene are based on its free radical quenching ability, we tested the antioxidant potential of fullerene micellar solutions. Lipid peroxidation tests showed that the micellar solutions of fullerene with Triton and polyoxyethylene lauryl ether kept high radical scavenging activity, comparable to that of aqueous suspension of fullerene and BHT. The results of this work provide a platform for further solubilization and testing of pristine fullerene and its hydrophobic derivatives in a biological benign environment. PMID:20828997

  20. Size-exclusive Nanosensor for Quantitative Analysis of Fullerene C60: A Concept Paper

    EPA Science Inventory

    This paper presents the first development of a mass-sensitive nanosensor for the isolation and quantitative analyses of engineered fullerene (C60) nanoparticles, while excluding mixtures of structurally similar fullerenes. Amino-modified beta cyclodextrin (β-CD-NH

  1. Fullerene-based Schottky-junction organic solar cells: a brief review

    NASA Astrophysics Data System (ADS)

    Sutty, Sibi; Williams, Graeme; Aziz, Hany

    2014-01-01

    Recent advances in fullerene-based Schottky organic solar cells (OSCs) are presented, with a focus on the current understanding of device physics. Fullerene-based Schottky OSCs attain high open-circuit voltages due to the n-type Schottky junction formed between fullerene and an adjacent high work function anode. Small concentrations of donor material doped into the fullerene matrix serve as efficient exciton dissociation and hole transport agents that can substantially bolster short-circuit currents and fill factors. As a consequence, fullerene-based Schottky OSCs have been demonstrated to provide some of the highest-performance vacuum-deposited small molecule OSCs, with power conversion efficiencies up to 8.1%. Fullerene-based Schottky OSCs constructed using different donor materials and varying cathode buffer layers, as studied by a number of different research groups, are presented. To elucidate the differences between Schottky OSCs and more traditional bulk-heterojunction OSCs, we discuss the photophysics of fullerenes, the role of the donor material, and charge transport in low donor concentration active layers. Fullerene-based Schottky OSCs possess considerable advantages because they can reach high efficiencies with a simple structure using readily available and cost-effective materials. The impact and applicability of the Schottky device architecture on the field of organic photovoltaics at large are discussed.

  2. Size-exclusive Nanosensor for Quantitative Analysis of Fullerene C60: A Concept Paper

    EPA Science Inventory

    This paper presents the first development of a mass-sensitive nanosensor for the isolation and quantitative analyses of engineered fullerene (C60) nanoparticles, while excluding mixtures of structurally similar fullerenes. Amino-modified beta cyclodextrin (?-CD-NH

  3. The Origin of Fullerenes in the 65 Myr Old Cretaceous/Tertiary Boundary

    NASA Technical Reports Server (NTRS)

    Becker, L.; Poreda, R. J.; Bunch, T. E.

    2000-01-01

    In this work we have searched for extraterrestrial (ET) helium (He) in fullerenes isolated from several K/T boundary (KTB) sediments. Measurements of He in these KTB fullerene residues revealed He-3/He-4 ratios that can only be explained as ET in origin.

  4. Water-soluble fullerene materials for bioapplications: photoinduced reactive oxygen species generation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The photoinduced reactive oxygen species (ROS) generation from several water-soluble fullerenes was examined. Macromolecular or small molecular water-soluble fullerene complexes/derivatives were prepared and their 1O2 and O2•- generation abilities were evaluated by EPR spin-trapping methods. As a r...

  5. Changes in Agglomeration of Fullerenes During Ingestion and Excretion in Thamnocephalus Platuyrus

    EPA Science Inventory

    The crustacean Thamnocephalus platyurus was exposed to aqueous suspensions of fullerenes C60 and C70. Aqueous fullerene suspensions were formed by stirring C60 and C70 as received from a commercial vendor in deionized water (term...

  6. Changes in Agglomeration of Fullerenes During Ingestion and Excretion in Thamnocephalus Platyurus

    EPA Science Inventory

    The crustacean Thamnocephalus platyurus was exposed to aqueous suspensions of fullerenes C60 and C70. Aqueous fullerene suspensions were formed by stirring C60 and C70 as received from a commercial vendor in deionized water (termed aqu/C60 and aqu/C70) for approximately 100 d. Th...

  7. Cathodoluminescence studies of C{sub 60} fullerene-based films and nanostructures

    SciTech Connect

    Nashchekin, A. V. Baryshev, S. V.; Sokolov, R. V.; Usov, O. A.

    2007-08-15

    The objects of investigation in this work are submicron Cm fullerene-based films and fullerene nanostructures fabricated by electron-beam lithography. The set of techniques for studying the fullerenes is extended due to attraction of the spectral cathodoluminescence (CL) to either of the initial fullerene films or submicron net structures with period of about 0.9 {mu}m, wall height 0.6 {mu}m, and width about 0.4 {mu}m.The maxima of the CL spectra of the initial C{sub 60} films are in good agreement with the energy-band structure of the amorphous fullerene film. In turn, the CL spectrum of the fullerene net structures possesses both peculiarities of the fullerene energy-band structure and it clearly exhibits the oscillations of the spectrum with a period as large as 0.08 eV. Such periodical fullerence net structures possess the properties of an optical resonator on the system 'fullerene net (n = 2.3)-air (n = 1).'.

  8. Addressing asymmetry of the charge and strain in a two-dimensional fullerene peapod.

    PubMed

    Vale, V; Verhagen, T; Vejpravov, J; Frank, O; Kalb?, M

    2015-12-23

    We prepared a two-dimensional C70 fullerene peapod by the sequential assembly of (12)C graphene, C70 fullerenes and (13)C graphene. The local changes in the strain and doping were correlated with local roughness revealing asymmetry in the strain and doping with respect to the top and bottom graphene layers of the peapod. PMID:26661834

  9. Synthesis of condensed phases containing polycyclic aromatic hydrocarbons fullerenes and nanotubes

    DOEpatents

    Reilly, Peter T. A.

    2004-10-19

    The invention relates to methods for producing polycyclic aromatic hydrocarbons, fullerenes, and nanotubes, comprising: a. heating at least one carbon-containing material to form a condensed phase comprising at least one polycyclic aromatic hydrocarbon; b. collecting at least some of the condensed phase; c. reacting the condensed phase to form fullerenes and/or nanotubes.

  10. Plasma-Chemical Synthesis of Nanosized Powders-Nitrides, Carbides, Oxides, Carbon Nanotubes and Fullerenes

    NASA Astrophysics Data System (ADS)

    Katerina, Zaharieva; Gheorghi, Vissokov; Janis, Grabis; Slavcho, Rakovsky

    2012-11-01

    In this article the plasma-chemical synthesis of nanosized powders (nitrides, carbides, oxides, carbon nanotubes and fullerenes) is reviewed. Nanosized powders - nitrides, carbides, oxides, carbon nanotubes and fullerenes have been successfully produced using different techniques, technological apparatuses and conditions for their plasma-chemical synthesis.

  11. Wobbling The Galactic Disk with Bombardment of Satellite Galaxies

    NASA Astrophysics Data System (ADS)

    D'Onghia, Elena

    We propose to assess the effect of impacts of large visible satellite galaxies on a disk, as well as the relevance of the continuing bombardment of the Galactic disk by dark matter clumps as predicted by the current cosmological framework that can wobble the disk, heating it and eventually exciting ragged spiral structures. In particular, we make detailed predictions for observable features such as spiral arms, rings and their associated stars in galactic disks and relate them to the physical processes that drive their formation and evolution in our Milky Way galaxy and nearby spirals. To do this, we will combine analytic methods and numerical simulations that allow us to calculate observables, which we will compare to present and forthcoming observations. Our methodology utilizes a combination of state of the art hydrodynamic simulations of galaxy evolution and multi- wavelength radiative transfer simulations. Our primary goals are: (1) To identify the physical processes that are responsible for spiral structure formation observed in our Milky Way and nearby disk galaxies, from the flocculent to grand- designed spiral galaxies and to provide observable signatures to be compared with data on nearby galaxies combining maps of 24 micron emission (Spitzer) and cold gas, CO (Heracles) and HI (THINGS). (2) To explore different morphologies of spiral galaxies: from the multi-armed galaxies to the Milky Way sized galaxies with few arms. (3) For a Milky Way disk we will assess the effect of impacts of substructures passing through the disk to origin the asymmetry in the number density of stars recently discovered from SDSS and SEGUE data and confirmed from RAVE data. We will also investigate the disk heating in the vertical plane due to the formation of vertical oscillations that are produced by the impact and migration of stars in the disk as consequence of the heating as compared to the classical stellar migration mechanism. (4) We will measure the spiral pattern speed and the velocity ellipsoid of the stars, and we will determine the contribution of the spiral arms to the heating of the stellar disk and to the radial migration of stars in the disk when the disk is perturbed by internal agents as giant molecular clouds. Our methodology has the potential to discern the detailed physical processes occurring in stellar disks with higher detail compared to previous simulations done in isolation or cosmological simulations of individual galaxies. The results of our work will provide a comprehensive guide for interpreting observations from upcoming GAIA, SDSS-IV, Spitzer and HST and future observations with JWST.

  12. Linear Stability and Instability Patterns in Ion Bombarded Silicon Surfaces

    NASA Astrophysics Data System (ADS)

    Madi, Charbel Said

    2011-12-01

    This thesis is a combined experimental and theoretical study of the fundamental physical mechanisms governing nanoscale surface morphology evolution of Ar + ion bombarded silicon surfaces. I experimentally determined the topographical phase diagram resulting from Ar+ ion irradiation of Si surfaces at room temperature in the linear regime of surface dynamics as we vary the control parameters ion beam energy and incidence angle. At all energies, it is characterized by a diverging wavelength bifurcation from a smooth stable surface to parallel mode ripples (wavevector parallel to the projected ion beam on the surface) as the ion beam incidence angle is varied. At sufficiently high angles theta ? 85, I observed perpendicular mode ripples (wavevector perpendicular to the ion beam). Through real-time Grazing-Incidence Small Angle X-ray Scattering, I have definitively established that ion-induced erosion, which is the consensus predominant cause of pattern formation, is not only of the wrong sign to explain the measured curvature coefficients responsible in driving the surface dynamics, but also is so small in magnitude as to be essentially negligible for pattern formation except possibly at the most grazing angles of incidence where both erosion and redistribution effects converge to zero. That the contribution of ion impact induced prompt atomic redistribution effects entirely overwhelms that of erosion in both the stabilizing and destabilizing regimes is of profound significance, as it overturns the erosion-based paradigm that has dominated the pattern formation field for over two decades. In situ wafer curvature measurements using the Multi-beam Optical Stress Sensor system were performed during amorphization of silicon by normal incidence 250 eV ion irradiation. An average compressive saturation stress built up in the amorphous layer was found to be as large as 1.5 GPa. By assuming the ion-induced amorphization layer to be modeled as a viscoelastic film that is anisotropically stressed by ion beam irradiation, we measure the deformation imparted per ion due to anisotropic deformation to be equal to A =1.15x10-16 cm2/ion. Although compressive stress is being injected into a thin viscoelastic ion-stimulated surface layer, the surface is unconditionally stable to topographic perturbations, corroborating the measured experimental phase diagram.

  13. Classical-trajectory Monte Carlo calculations of the electronic stopping cross section for keV protons and antiprotons impinging on hydrogen atoms

    SciTech Connect

    Custidiano, Ernesto R.; Jakas, Mario M.

    2005-08-15

    Using the classical-trajectory Monte Carlo (CTMC) method, the electronic stopping cross sections of hydrogen atoms by protons and antiprotons impact are calculated. The results show that the CTMC method compares fairly well with previous quantum mechanics calculations of the stopping cross sections for the same colliding pairs. It turns out therefore that the CTMC method constitutes a reliable and, computationally speaking, convenient alternative to calculate the stopping of ions in matter. The present results also show that the stopping appears to be particularly sensitive to the angular momentum (L) of the electron orbit. In the case of protons, the highest sensitivity to L becomes evident around the energy of the maximum stopping. While for antiprotons the largest sensitivity of the stopping to L is observed down at low bombarding energies, i.e., below 10 keV.

  14. Ag K-shell ionization by electron impact: New cross-section measurements between 50 and 100 keV and review of previous experimental data

    NASA Astrophysics Data System (ADS)

    Vanin, V. R.; Manso Guevara, M. V.; Maidana, N. L.; Martins, M. N.; Fernández-Varea, J. M.

    2016-02-01

    We report the measurement of Ag K-shell ionization cross-section by electron impact in the range 50-100 keV and review the experimental data found in the literature. The sample consisted in a thin film of Ag evaporated on a thin C backing. The x-ray spectra generated by electron bombardment in the São Paulo Microtron were observed with a planar HPGe detector. The ratios between characteristic and bremsstrahlung x-ray yields were transformed to ionization cross sections with the help of theoretical atomic-field bremsstrahlung cross sections. The measured cross sections are compared with existing experimental values and calculations based on the semi-relativistic distorted-wave Born approximation. According to our experiment, the ratio of Ag Kβ to Kα x-ray intensities is 0.2018(24).

  15. Dedicated STEM for 200 to 40 keV operation

    NASA Astrophysics Data System (ADS)

    Dellby, N.; Bacon, N. J.; Hrncirik, P.; Murfitt, M. F.; Skone, G. S.; Szilagyi, Z. S.; Krivanek, O. L.

    2011-06-01

    A dedicated STEM developed for operation at primary energies from 200 keV to 40 keV and lower is described. It has a new cold field emission gun (CFEG) that gives a normalized brightness of 3 × 108 A/(m2 sr V), and excellent short-term and long-term stability. It includes two gun lenses (one electrostatic and one electromagnetic), a fast electrostatic beam blanker, three condenser lenses, a corrector of third- and fifth-order geometric aberrations, an objective lens with low aberration coefficients, a flexible set of projector lenses, an ultra-stable sample stage, and provision for storing up to five samples under high vacuum and loading them into the microscope's objective lens under remote control. The microscope is enclosed in a magnetically and acoustically shielding enclosure, which allows it to operate at a high performance level even in non-optimal environments. It has reached 53 pm resolution at 200 keV and 123 pm at 40 keV, and an EELS energy resolution of 0.26 eV. Dedicated to Christian Colliex

  16. KevJumba and the Adolescence of YouTube

    ERIC Educational Resources Information Center

    Saul, Roger

    2010-01-01

    This article considers the significance of YouTube as a pedagogical space from which young people can play participatory roles as theorists in their own constructions as popular cultural subjects. Drawing upon the public profile of "KevJumba," a teenager who makes videos of himself on YouTube, the article suggests that representational practices

  17. Compact 300 keV electron gun for radiation processing

    SciTech Connect

    Auditore, L.; Barna, R.C.; De Pasquale, D.; Interdonato, S.; Italiano, A.; Trifiro, A.; Trimarchi, M.

    2005-12-15

    A new self-shielded system for surface radiation treatments has been developed, based on a 300 keV electron gun, able to irradiate a 100 mmx10 mm area. The compact and durable system described in this paper provides the required dose of treatment for several industrial or scientific research applications, with a good reproducibility of the parameters.

  18. KevJumba and the Adolescence of YouTube

    ERIC Educational Resources Information Center

    Saul, Roger

    2010-01-01

    This article considers the significance of YouTube as a pedagogical space from which young people can play participatory roles as theorists in their own constructions as popular cultural subjects. Drawing upon the public profile of "KevJumba," a teenager who makes videos of himself on YouTube, the article suggests that representational practices…

  19. Encapsulation of radioactive isotopes into C 60 fullerene cage by recoil implantation technique

    NASA Astrophysics Data System (ADS)

    Saha, S. K.; Chowdhury, D. P.; Das, S. K.; Guin, R.

    2006-02-01

    Radioactive isotopes 24Na, 34 mCl, 65Zn, 69Ge, 71As, 72, 73, 75 Se, 77Br, 79Kr, 81Rb, 83Sr, 86Zr and 168Hf with recoil energy 3 MeV were implanted in thin film of C 60 for the formation of radioactive endohedral fullerenes by recoil implantation technique. The isotopes of interest were produced by 93-120 MeV 16O, 14N beams from Variable Energy Cyclotron Centre, Kolkata. Since direct interaction of primary heavy ion beams with the fullerene film was avoided in our experimental condition, the damage or degradation of the fullerene matrix could be reduced to insignificant level. The endohedral fullerenes formed were separated radio-chemically and the probabilities of formation of radioactive endohedral fullerenes from different isotopes were determined by ?-spectrometry.

  20. Optical limiting and excited-state absorption in fullerene solutions and doped glasses

    SciTech Connect

    McBranch, D.; Smilowitz, L.; Klimov, V.

    1995-09-01

    We report the ground state and excited state optical absorption spectra in the visible and near infrared for several substituted fullerenes and higher fullerenes in toluene solutions. Based on these measurements, broadband predictions of the optical limiting performance of these molecules can be deduced. These predictions are then tested at 532 to 700 nm in intensity-dependent transmission measurements. We observe optical limiting in all fullerenes measured; higher fullerenes show the greatest potential for limiting in the near infrared (650-1000 nm), while substituted C{sub 60} shows optimal limiting in the visible (450-700 nm). We observe dramatically reduced limiting for solid forms of C{sub 60} (thin films and C{sub 60}-doped porous glasses), indicating that efficient optical limiting in fullerenes requires true molecular solutions.

  1. OSSE observations of galactic 511 keV annihilation radiation

    NASA Technical Reports Server (NTRS)

    Purcell, W. R.; Grabelsky, D. A.; Johnson, W. N.; Jung, G. V.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Ulmer, M. P.

    1992-01-01

    The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma-Ray Observatory has performed several observations of the galactic plane and galactic center region to measure the distribution of galactic 511 keV positron annihilation radiation. Preliminary analysis of data collected during the observation of the galactic center region over the period 13-24 Jun. 1991, indicates the presence of a 511 keV line and positronium continuum superimposed on a power-law continuum. The line of flux was found to be (2.7 +/- 0.5) x 10(exp -4) gamma/sq cm sec, with a positronium fraction of (0.9 +/- 0.2). The 3(sigma) upper limit to daily variations in the 511 keV line flux from the mean during the observation interval is 3 x 10(exp -4) gamma/sq cm sec. If all of the observed annihilation radiation is assumed to originate from the x-ray source 1E 1740.7-2942, the corresponding 511 keV line flux would be (3.0 +/- 0.6) x 10(exp -4) gamma/sq cm sec. The 3(sigma) upper limit for 511 keV line emission from the x-ray binary GX1+4 is 6 x 10(exp -4) gamma/sq cm sec. Results from the galactic plane observations at galactic longitudes of 25 degrees (16-21 Aug. 1991) and 339 degrees (6-11 Sep. 1991) suggest that the emission is concentrated near the galactic center. The observations and the preliminary results are described.

  2. Influence of C{sub 60} morphology on high-order harmonic generation enhancement in fullerene-containing plasma

    SciTech Connect

    Ganeev, R. A.; Singhal, H.; Naik, P. A.; Chakera, J. A.; Srivastava, A. K.; Dhami, T. S.; Joshi, M. P.; Gupta, P. D.

    2009-11-15

    The morphologies of the fullerene targets and the ablated fullerenes to determine the optimal conditions of excitation of the C{sub 60}-containing targets have been analyzed. The optimization of fullerene-containing plasma conditions allowed the enhanced harmonic generation in these plasmas using laser radiation of different wavelengths, pulse durations, and phase modulation. A comparison between the harmonic generation in single-atom/ion-containing plasmas (using bulk carbon, silver, and indium targets) and fullerene-rich plasma plumes showed better conversion efficiency for the latter medium. The influence of phase modulation of the fundamental radiation in fullerene plasmas on the spectral properties of harmonics has been studied.

  3. Energy spectra of sputtered positive ions under Cs + bombardment

    NASA Astrophysics Data System (ADS)

    Gnaser, Hubert

    2011-05-01

    The emission-energy spectra of atomic and molecular secondary ions sputtered from various metals and semiconductors (Al, Cu, In, Si, InP, and InSb) under 5.5-keV Cs + irradiation were investigated. The emitted ions were detected in a high-sensitivity double-focusing secondary-ion mass spectrometer. Specifically, the energy distributions of Cs +, Cs2+, MCs +, and M + ions (where M designates one of the target elements) were recorded for emission energies E ? 125 eV. All ion species exhibit a peak at low energy ( E < 5 eV), but differ significantly in the respective fall-off to high emission energies. The influence of the oxygen partial pressure in the vicinity of the sputtered surface on the energy spectra was examined for Cs + ions emitted from Si. With an increase of the ratio r of the O 2 flux to the Cs + flux, the spectra shift to higher emission-energy values, with the total shift amounting to 0.45 eV at a value of r 3.3. Concurrently, the intensity of Cs + increases by 30%. The measured emission distributions of Cs + ions from different samples were compared with the predictions of the electron-tunneling model of secondary-ion formation. It is found that the experimental spectra can be reproduced quite well when employing specific sets of parameters in that theoretical concept. The possible limitations of such a comparison are discussed.

  4. Front-side-bombarded metal-plated CMOS electron sensors

    NASA Astrophysics Data System (ADS)

    Finkelstein, Hod; Ginosar, Ran

    1998-04-01

    Electron detector arrays are employed in numerous imaging applications, from low-light-level imaging to astronomy, electron microscopy, and nuclear instrumentation. The majority of these detectors are fabricated with dedicated processes, use the semiconductor as a stopping and detecting layer, and utilize CCD-type charge transfer and detection. We present a new detector, wherein electrons are stopped by an exposed metal layer, and are subsequently detected either through charge collection in a CCD-type well, or by a measurement of a potential drop across a capacitor which is discharged by these electrons. Spatial localization is achieved by use of two metal planes, one for protecting the underlying gate structures, and another, with metal pixel structures, for 2D detection. The new deice doe not suffer from semiconductor non-uniformities, and blooming effects are minimized. It is effective for electrons with energies of 2-6 keV. The unique structure makes it possible to achieve a high fill factor, and to incorporate on-chip processing. An imaging chip implementing several test structures incorporating the new detector has been fabricated using a 2 micron double-poly double-metal process, and has been tested inside a JEOL 6400 electron microscope.

  5. Importance of the donor:fullerene intermolecular arrangement for high-efficiency organic photovoltaics.

    PubMed

    Graham, Kenneth R; Cabanetos, Clement; Jahnke, Justin P; Idso, Matthew N; El Labban, Abdulrahman; Ngongang Ndjawa, Guy O; Heumueller, Thomas; Vandewal, Koen; Salleo, Alberto; Chmelka, Bradley F; Amassian, Aram; Beaujuge, Pierre M; McGehee, Michael D

    2014-07-01

    The performance of organic photovoltaic (OPV) material systems are hypothesized to depend strongly on the intermolecular arrangements at the donor:fullerene interfaces. A review of some of the most efficient polymers utilized in polymer:fullerene PV devices, combined with an analysis of reported polymer donor materials wherein the same conjugated backbone was used with varying alkyl substituents, supports this hypothesis. Specifically, the literature shows that higher-performing donor-acceptor type polymers generally have acceptor moieties that are sterically accessible for interactions with the fullerene derivative, whereas the corresponding donor moieties tend to have branched alkyl substituents that sterically hinder interactions with the fullerene. To further explore the idea that the most beneficial polymer:fullerene arrangement involves the fullerene docking with the acceptor moiety, a family of benzo[1,2-b:4,5-b']dithiophene-thieno[3,4-c]pyrrole-4,6-dione polymers (PBDTTPD derivatives) was synthesized and tested in a variety of PV device types with vastly different aggregation states of the polymer. In agreement with our hypothesis, the PBDTTPD derivative with a more sterically accessible acceptor moiety and a more sterically hindered donor moiety shows the highest performance in bulk-heterojunction, bilayer, and low-polymer concentration PV devices where fullerene derivatives serve as the electron-accepting materials. Furthermore, external quantum efficiency measurements of the charge-transfer state and solid-state two-dimensional (2D) (13)C{(1)H} heteronuclear correlation (HETCOR) NMR analyses support that a specific polymer:fullerene arrangement is present for the highest performing PBDTTPD derivative, in which the fullerene is in closer proximity to the acceptor moiety of the polymer. This work demonstrates that the polymer:fullerene arrangement and resulting intermolecular interactions may be key factors in determining the performance of OPV material systems. PMID:24932575

  6. Effects of Mo Seeding on the Formation of Si Nanodots During Low-Energy Ion Bombardment

    SciTech Connect

    Ozaydin,G.; Ludwig, Jr., K.; Zhou, H.; Headrick, R.

    2008-01-01

    Effects of seed atoms on the formation of nanodots on silicon surfaces during normal incidence Ar+ ion bombardment at room temperature are studied with real-time grazing-incidence small-angle x-ray scattering (GISAXS), real-time wafer curvature stress measurements and ex situ atomic force microscopy. Although Si surfaces remain smooth during bombardment at room temperature, when a small amount of Mo atoms is supplied to the surface during ion bombardment, the development of correlated structures ('dots') is observed. Stress measurements show that initially a compressive stress develops during bombardment, likely due to amorphization of the surface and insertion of argon. However, seeding causes a larger tensile stress to develop with further bombardment, possibly due to the formation of higher density regions around the Mo seed atoms on the surface. Detailed fits of the GISAXS evolution during nanostructure growth show that the instability is larger than predicted by the Bradley-Harper theory of curvature-dependent sputter yield. These results suggest that the tensile stress is playing a dominant role in driving the nanodot formation.

  7. Ultra-low-energy (<10 eV/u) ion beam bombardment effect on naked DNA

    NASA Astrophysics Data System (ADS)

    Thopan, P.; Thongkumkoon, P.; Prakrajang, K.; Suwannakachorn, D.; Yu, L. D.

    2014-05-01

    Since ion energy deposition in the ion-bombarded materials dominantly occurs in the low-energy range, it is very interesting to know effects from ultra-low-energy ion interaction with DNA for understanding ion-beam-induced genetic mutation. Tens-keV Ar- and N-ion beams were decelerated to ultra-low energy ranging from 20 to 100 eV, or only a few to 10 eV/u, to bombard naked plasmid DNA. The bombarded DNA was analyzed using gel electrophoresis for DNA form changes. The original DNA supercoiled form was found to change to relaxed and linear forms, indicating single or double strand breaks after bombarded by tens-eV ion beam. N-ion beam was found more effective in inducing DNA change and mutation than Ar-ion beam. The study demonstrated that the ion bombardment with energy as low as several-tens eV was able to break DNA strands and thus potentially to cause genetic modification of biological cells. The experimental results were discussed in terms of direct atomic collision between the ions and DNA atoms.

  8. On the origin of microcraters on the surface of ion beam bombarded plant cell walls

    NASA Astrophysics Data System (ADS)

    Salvadori, M. C.; Teixeira, F. S.; Brown, I. G.

    2006-01-01

    Ion bombardment of plant and bacterial cellular material has recently been used as a tool for the transfer of exogenous DNA macromolecules into the cell interior region. The precise mechanism that leads to the transfer of macromolecules through the cell envelope is not yet clear, however it has been observed that the ion bombardment is accompanied by the formation of "microcraters" on the cell wall, and it is possible that these features provide channels for the macromolecule transfer. Thus the nature and origin of the microcraters is of importance to understanding the DNA transfer phenomenon as well as being of fundamental interest. We report here on some scanning electron microscope observations we have made of onion skin cells that have been subjected to electron beam bombardment of sufficiently high power density to damage the cell wall. The damage seen is much less than and different from the microcraters formed subsequent to ion bombardment. We speculate that the microcraters may originate from the explosive release of gas generated in the biomaterial by ion bombardment.

  9. Thermal/electron irradiation assisted coalescence of Sc3N@C80 fullerene in carbon nanotube and evidence of charge transfer between pristine/coalesced fullerenes and nanotubes

    NASA Astrophysics Data System (ADS)

    Fallah, Ahmadreza; Yonetani, Yuki; Senga, Ryosuke; Hirahara, Kaori; Kitaura, Ryo; Shinohara, Hisanori; Nakayama, Yoshikazu

    2013-11-01

    Sc3N@C80 fullerenes are inserted inside carbon nanotubes (CNTs). The results show that the thermal stability of Sc3N@C80 fullerenes is around 1200 C for the fullerenes resting on the wall of CNTs. Internal fullerenes show stability up to 1300 C, which portrays them as one of most stable types of fullerenes. Electron irradiation of the peapods at 90 kV leads to the formation of capsules inside the CNTs at 5 109 e nm-2 electron dosage. This value is an order of magnitude higher than the threshold of electron-induced damage in C60 molecules. Electron energy loss spectroscopy confirms the presence of Sc atoms in capsules. Encapsulation of fullerenes and capsule formation changes the oxidation state of Sc atoms from +2.5 towards +3. This is an evidence of charge transfer between the fullerene/capsule cage and CNT walls.

  10. Influence of organic ions on DNA damage induced by 1 eV to 60 keV electrons

    SciTech Connect

    Zheng Yi; Sanche, Leon

    2010-10-21

    We report the results of a study on the influence of organic salts on the induction of single strand breaks (SSBs) and double strand breaks (DSBs) in DNA by electrons of 1 eV to 60 keV. Plasmid DNA films are prepared with two different concentrations of organic salts, by varying the amount of the TE buffer (Tris-HCl and EDTA) in the films with ratio of 1:1 and 6:1 Tris ions to DNA nucleotide. The films are bombarded with electrons of 1, 10, 100, and 60 000 eV under vacuum. The damage to the 3197 base-pair plasmid is analyzed ex vacuo by agarose gel electrophoresis. The highest yields are reached at 100 eV and the lowest ones at 60 keV. The ratios of SSB to DSB are surprisingly low at 10 eV ({approx}4.3) at both salt concentrations, and comparable to the ratios measured with 100 eV electrons. At all characteristic electron energies, the yields of SSB and DSB are found to be higher for the DNA having the lowest salt concentration. However, the organic salts are more efficient at protecting DNA against the damage induced by 1 and 10 eV electrons. DNA damage and protection by organic ions are discussed in terms of mechanisms operative at each electron energy. It is suggested that these ions create additional electric fields within the groove of DNA, which modify the resonance parameter of 1 and 10 eV electrons, namely, by reducing the electron capture cross-section of basic DNA units and the lifetime of corresponding transient anions. An interstrand electron transfer mechanism is proposed to explain the low ratios for the yields of SSB to those of DSB produced by 10 eV electrons.

  11. Comparative Computational Study of Interaction of C60-Fullerene and Tris-Malonyl-C60-Fullerene Isomers with Lipid Bilayer: Relation to Their Antioxidant Effect

    PubMed Central

    Bozdaganyan, Marine E.; Orekhov, Philipp S.; Shaytan, Alexey K.; Shaitan, Konstantin V.

    2014-01-01

    Oxidative stress induced by excessive production of reactive oxygen species (ROS) has been implicated in the etiology of many human diseases. It has been reported that fullerenes and some of their derivativescarboxyfullerenesexhibits a strong free radical scavenging capacity. The permeation of C60-fullerene and its amphiphilic derivativesC3-tris-malonic-C60-fullerene (C3) and D3-tris-malonyl-C60-fullerene (D3)through a lipid bilayer mimicking the eukaryotic cell membrane was studied using molecular dynamics (MD) simulations. The free energy profiles along the normal to the bilayer composed of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) for C60, C3 and D3 were calculated. We found that C60 molecules alone or in clusters spontaneously translocate to the hydrophobic core of the membrane and stay inside the bilayer during the whole period of simulation time. The incorporation of cluster of fullerenes inside the bilayer changes properties of the bilayer and leads to its deformation. In simulations of the tris-malonic fullerenes we discovered that both isomers, C3 and D3, adsorb at the surface of the bilayer but only C3 tends to be buried in the area of the lipid headgroups forming hydrophobic contacts with the lipid tails. We hypothesize that such position has implications for ROS scavenging mechanism in the specific cell compartments. PMID:25019215

  12. On novel magnetic probe for fullerene characterization: Theoretical studies on NMR parameters of free and confined in fullerenes HD and H2 molecules.

    PubMed

    Jankowska, Marzena; Kupka, Teobald; Stobi?ski, Leszek

    2015-11-01

    Chemical characterization and separation of individual fullerenes from a raw reaction mixture need new and efficient tools, including rapid spectroscopic techniques. Recent "molecular surgery" synthesis of endohedral complexes of fullerenes with selected atoms and small molecules has opened a new path for experimental and theoretical studies on structural and spectroscopic properties of these molecular systems. Among them are fullerenes with molecular hydrogen confined within a nanoscale cavity. In this work we report on quantum-chemical prediction of nuclear magnetic shielding (and chemical shift) and indirect spin-spin coupling constant in free HD and H2 molecules, as well as models of confined dihydrogen using the coupled cluster with single and double excitations (CCSD) and density functional theory (DFT) levels of theory. Inspired with the recent experimental NMR studies on HD and H2 molecules confined inside C60 fullerene we systematically investigated the sensitivity of (1)H nuclear magnetic shielding of H2 and indirect spin-spin coupling constant (1)JHD in HD molecules to the interatomic separation in the gas phase, in the presence of benzene and inside fullerene cages of different size. The sensitivity of both NMR parameters to confinement is discussed in terms of very weak non-covalent interactions of HD and H2 with fullerene cage. PMID:26349996

  13. Functionalized fullerene (C??) as a potential nanomediator in the fabrication of highly sensitive biosensors.

    PubMed

    Afreen, Sadia; Muthoosamy, Kasturi; Manickam, Sivakumar; Hashim, Uda

    2015-01-15

    Designing a biosensor for versatile biomedical applications is a sophisticated task and how dedicatedly functionalized fullerene (C60) can perform on this stage is a challenge for today and tomorrow's nanoscience and nanotechnology. Since the invention of biosensor, many ideas and methods have been invested to upgrade the functionality of biosensors. Due to special physicochemical characteristics, the novel carbon material "fullerene" adds a new dimension to the construction of highly sensitive biosensors. The prominent aspects of fullerene explain its outstanding performance in biosensing devices as a mediator, e.g. fullerene in organic solvents exhibits five stages of reversible oxidation/reduction, and hence fullerene can work either as an electrophile or nucleophile. Fullerene is stable and its spherical structure produces an angle strain which allows it to undergo characteristic reactions of addition to double bonds (hybridization which turns from sp(2) to sp(3)). Research activities are being conducted worldwide to invent a variety of methods of fullerene functionalization with a purpose of incorporating it effectively in biosensor devices. The different types of functionalization methods include modification of fullerene into water soluble derivatives and conjugation with enzymes and/or other biomolecules, e.g. urease, glucose oxidase, hemoglobin, myoglobin (Mb), conjugation with metals e.g. gold (Au), chitosan (CS), ferrocene (Fc), etc. to enhance the sensitivity of biosensors. The state-of-the-art research on fullerene functionalization and its application in sensor devices has proven that fullerene can be implemented successfully in preparing biosensors to detect glucose level in blood serum, urea level in urine solution, hemoglobin, immunoglobulin, glutathione in real sample for pathological purpose, to identify doping abuse, to analyze pharmaceutical preparation and even to detect cancer and tumor cells at an earlier stage. Employing fullerene-metal matrix for the detection of tumor and cancer cells is also possible by the inclusion of fullerene in single-walled carbon nanotubes (SWCNTs) known as peapods as well as in double-walled carbon nanotubes (DWCNTs), to augment the effectiveness of biosensors. This review discusses various approaches that have been reported for functionalizing fullerene (C60) derivatives and their application in different types of biosensor fabrication. PMID:25125029

  14. Keeping the ball rolling: fullerene-like molecular clusters.

    PubMed

    Kong, Xiang-Jian; Long, La-Sheng; Zheng, Zhiping; Huang, Rong-Bin; Zheng, Lan-Sun

    2010-02-16

    The discovery of fullerenes in 1985 opened a new chapter in the chemistry of highly symmetric molecules. Fullerene-like metal clusters, characterized by (multi)shell-like structures, are one rapidly developing class of molecules that share this shape. In addition to creating aesthetically pleasing molecular structures, the ordered arrangement of metal atoms within such frameworks provides the opportunity to develop materials with properties not readily achieved in corresponding mononuclear or lower-nuclearity complexes. In this Account, we survey the great variety of fullerene-like metal-containing clusters with an emphasis on their synthetic and structural chemistry, a first step in the discussion of this fascinating field of cluster chemistry. We group the compounds of interest into three categories based on the atomic composition of the cluster core: those with formal metal-metal bonding, those characterized by ligand participation, and those supported by polyoxometalate building blocks. The number of clusters in the first group, containing metal-metal bonds, is relatively small. However, because of the unique and complex bonding scenarios observed for some of these species, these metalloid clusters present a number of research questions with significant ramifications. Because these cores contain molecular clusters of precious metals at the nanoscale, they offer an opportunity to study chemical properties at size ranges from the molecular to nanoscale and to gain insights into the electronic structures and properties of nanomaterials of similar chemical compositions. Clusters of the second type, whose core structures are facilitated by ligand participation, could aid in the development of functional materials. Of particular interest are the magnetic clusters containing both transition and lanthanide elements. A series of such heterometallic clusters that we prepared demonstrates diverse magnetic properties including antiferromagnetism, ferrimagnetism, and ferromagnetism. Considering the diversity of their composition, their distinct electronic structures, and the disparate coordination behaviors of the different metal elements, these materials suggest abundant opportunities for designing multifunctional materials with varied structures. The third type of clusters that we discuss are based on polyoxometalates, in particular those containing pentagonal units. However, unlike in fullerene chemistry, which does not allow the use of discrete pentagonal building blocks, the metal oxide-based pentagonal units can be used as fundamental building blocks for constructing various Keplerate structures. These structures also have a variety of functions, including intriguing magnetic properties in some cases. Coupled with different linking groups, such pentagonal units can be used for the assembly of a large number of spherical molecules whose properties can be tuned and optimized. Although this Account focuses on the topological aspects of fullerene-like metal clusters, we hope that this topical review will stimulate more efforts in the exploratory synthesis of new fullerene-like clusters. More importantly, we hope that further study of the bonding interactions and properties of these molecules will lead to the development of new functional materials. PMID:19764756

  15. Molecular dynamics simulations of sputtering of Langmuir-Blodgett multilayers by keV C60 projectiles

    PubMed Central

    Paruch, R.; Rzeznik, L.; Czerwinski, B.; Garrison, B. J.; Winograd, N.; Postawa, Z.

    2009-01-01

    Coarse-grained molecular dynamics computer simulations are applied to investigate fundamental processes induced by an impact of keV C60 projectile at an organic overlayer composed of long, well-organized linear molecules. The energy transfer pathways, sputtering yields, and the damage induced in the irradiated system, represented by a Langmuir-Blodgett (LB) multilayers composed from molecules of bariated arachidic acid, are investigated as a function of the kinetic energy and impact angle of the projectile and the thickness of the organic system. In particular, the unique challenges of depth profiling through a LB film vs. a more isotropic solid are discussed. The results indicate that the trajectories of projectile fragments and, consequently, the primary energy can be channeled by the geometrical structure of the overlayer. Although, a similar process is known from sputtering of single crystals by atomic projectiles, it has not been anticipated to occur during C60 bombardment due to the large size of the projectile. An open and ordered molecular structure of LB films is responsible for such behavior. Both the extent of damage and the efficiency of sputtering depend on the kinetic energy, the impact angle, and the layer thickness. The results indicate that the best depth profiling conditions can be achieved with low-energy cluster projectiles irradiating the organic overlayer at large off-normal angles. PMID:20174461

  16. Beyond fullerenes: design of nonfullerene acceptors for efficient organic photovoltaics.

    PubMed

    Li, Haiyan; Earmme, Taeshik; Ren, Guoqiang; Saeki, Akinori; Yoshikawa, Saya; Murari, Nishit M; Subramaniyan, Selvam; Crane, Matthew J; Seki, Shu; Jenekhe, Samson A

    2014-10-15

    New electron-acceptor materials are long sought to overcome the small photovoltage, high-cost, poor photochemical stability, and other limitations of fullerene-based organic photovoltaics. However, all known nonfullerene acceptors have so far shown inferior photovoltaic properties compared to fullerene benchmark [6,6]-phenyl-C60-butyric acid methyl ester (PC60BM), and there are as yet no established design principles for realizing improved materials. Herein we report a design strategy that has produced a novel multichromophoric, large size, nonplanar three-dimensional (3D) organic molecule, DBFI-T, whose π-conjugated framework occupies space comparable to an aggregate of 9 [C60]-fullerene molecules. Comparative studies of DBFI-T with its planar monomeric analogue (BFI-P2) and PC60BM in bulk heterojunction (BHJ) solar cells, by using a common thiazolothiazole-dithienosilole copolymer donor (PSEHTT), showed that DBFI-T has superior charge photogeneration and photovoltaic properties; PSEHTT:DBFI-T solar cells combined a high short-circuit current (10.14 mA/cm(2)) with a high open-circuit voltage (0.86 V) to give a power conversion efficiency of 5.0%. The external quantum efficiency spectrum of PSEHTT:DBFI-T devices had peaks of 60-65% in the 380-620 nm range, demonstrating that both hole transfer from photoexcited DBFI-T to PSEHTT and electron transfer from photoexcited PSEHTT to DBFI-T contribute substantially to charge photogeneration. The superior charge photogeneration and electron-accepting properties of DBFI-T were further confirmed by independent Xenon-flash time-resolved microwave conductivity measurements, which correctly predict the relative magnitudes of the conversion efficiencies of the BHJ solar cells: PSEHTT:DBFI-T > PSEHTT:PC60BM > PSEHTT:BFI-P2. The results demonstrate that the large size, multichromophoric, nonplanar 3D molecular design is a promising approach to more efficient organic photovoltaic materials. PMID:25265412

  17. Quantification of C60 fullerene concentrations in water.

    PubMed

    Chen, Zhuo; Westerhoff, Paul; Herckes, Pierre

    2008-09-01

    The growing usage of nanomaterials is causing emerging concern regarding their environmental behavior in aquatic environments. A major need is the capability to detect and quantify nanomaterials in complex water matrices. Carbon60 fullerene is of special interest because of the widespread application of nanocarbon technology. The present study focuses on how to separate and concentrate fullerenes from water containing salts and organic matter and then quantify their concentrations using liquid chromatography coupled with mass spectrometry (LC/MS). The stable aqueous C60 aggregates (nC60) prepared in the present study were approximately 60 to 70 nm in diameter and had an ultraviolet (UV) extinction coefficient of 0.0263 L/mg-cm at 347 nm, which equated to a UV detection limit of 0.4 mg/L based upon an absorbance of 0.01 cm(-1). Ultraviolet analysis is not applicable to use in waters containing salts or organics (e.g., tap water) because of their interferences and potential to aggregate nC60. The LS/MS analysis detected C60 as single fullerene rather than aggregates. Three techniques were developed to separate and concentrate nC60 from ultrapure and tap water into toluene to facilitate LC/MS determination: Evaporation of sample to dryness; extraction using 20% NaCl into toluene; and solid-phase extraction. The first two methods had limitations for use in complex water matrices, but aqueous nC60 concentration as low as 300 ng/L in water were quantified using solid-phase extraction (SPE) separation method. This is the first publication on the application of extraction methods for nC60 from ultrapure and tap waters and determination of detection limits by LC/MS. PMID:19086313

  18. Top-down formation of fullerenes in the interstellar medium

    PubMed Central

    Bern, O.; Montillaud, J.; Joblin, C.

    2015-01-01

    Fullerenes have been recently detected in various circumstellar and interstellar environments, raising the question of their formation pathway. It has been proposed that they can form at the low densities found in the interstellar medium by the photo-chemical processing of large polycyclic aromatic hydrocarbons (PAHs). Following our previous work on the evolution of PAHs in the NGC 7023 reflection nebula, we evaluate, using photochemical modeling, the possibility that the PAH C66H20 (i.e. circumovalene) can lead to the formation of C60 upon irradiation by ultraviolet photons. The chemical pathway involves full dehydrogenation of C66H20, folding into a floppy closed cage and shrinking of the cage by loss of C2 units until it reaches the symmetric C60 molecule. At 10 from the illuminating star and with realistic molecular parameters, the model predicts that 100% of C66H20 is converted into C60 in ~ 105 years, a timescale comparable to the age of the nebula. Shrinking appears to be the kinetically limiting step of the whole process. Hence, PAHs larger than C66H20 are unlikely to contribute significantly to the formation of C60, while PAHs containing between 60 and 66 C atoms should contribute to the formation of C60 with shorter timescales, and PAHs containing less than 60 C atoms will be destroyed. Assuming a classical size distribution for the PAH precursors, our model predicts absolute abundances of C60 are up to several 10?4 of the elemental carbon, i.e. less than a percent of the typical interstellar PAH abundance, which is consistent with observational studies. According to our model, once formed, C60 can survive much longer (> 107 years for radiation fields below G0 = 104) than other fullerenes because of the remarkable stability of the C60 molecule at high internal energies. Hence, a natural consequence is that C60 is more abundant than other fullerenes in highly irradiated environments. PMID:26722131

  19. Study on evolution of gases from fluoropolymer films bombarded with heavy ions

    NASA Astrophysics Data System (ADS)

    Minamisawa, Renato Amaral; Zimmerman, Robert Lee; Budak, Satilmis; Ila, Daryush

    2008-04-01

    Ion beam bombardment provides a unique way of material modification by inducing a high degree of localized electronic excitation. The ion track, or affected volume along the ion path through the material is related to the total damage and possible structural changes. Here we study the evolution of gases emitted by poly(tetrafluorethylene-co-perfluoro-(propyl vinyl ether)) (PFA) fluoropolymer bombarded with MeV gold ions. The gas was monitored by a residual gas analyzer (RGA), as a function of the ion fluence. Micro-Raman, atomic force microscopy and optical absorption were used to analyze the chemical structure changes and sputtering yield.

  20. On the ion-bombardment reduction mechanism. [of iron ions in lunar surface

    NASA Technical Reports Server (NTRS)

    Yin, L.; Tsang, T.; Adler, I.

    1976-01-01

    Recent laboratory studies of solar-wind reduction mechanisms on the lunar surface are discussed, emphasizing the effects of the electronic configurations of transition metals and the effects of covalent bonding. A series of experiments is described which involved argon ion bombardment of extremely thin targets consisting of simple halides and cyanides of first-row transition metals. Experimental results are summarized which imply that the cyanides generally have much higher reduction efficiencies than the halides. It is suggested that although reduction and sputtering take place concurrently under ion bombardment, they may actually be two independent processes.