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Sample records for kev fullerene bombardment

  1. Sublinear effect in light emission from cesium iodide bombarded by keV polyatomic projectiles

    NASA Astrophysics Data System (ADS)

    Baudin, K.; Parilis, E. S.; Blankenship, J. F.; Van Stipdonk, M. J.; Schweikert, E. A.

    1998-02-01

    Our experiments examined light emission from a CsI target bombarded with polyatomic projectiles [H n+, (NaF) nNa +, with n=1,2; Na +, Cs 2I +, Cs +] at 5-30 keV impact energies. The light emission increases with primary ion velocity as ( V - Vth) α, where Vth is a velocity threshold. The number of photons emitted under one cluster impact increases with the number of atoms in the projectile, displaying a sublinear effect, similar to that reported elsewhere for electron emission. The model of sweeping out electrons has been applied to explain and calculate the observed effect.

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

    NASA Astrophysics Data System (ADS)

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

    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.

  3. Part I. Fast atom bombardment mass spectrometry: Discrimination effects and matrix chemistry. Part II. High-energy collisional activation of fullerenes and alkaline earth monohalides

    SciTech Connect

    Caldwell, K.A.

    1992-01-01

    This dissertation describes fundamental studies encompassing two areas of mass spectrometry: fast-atom bombardment (FAB) ionization and collisional activation. Mixture analysis by FAB-MS is hindered by concentration-dependent discrimination arising from differences in surface activity and micelle formation (Chapter 1). The use of a nonpolar matrix, N-dodecanol, reduced the discrimination effects in the analysis of mixtures of saturated fatty acids. The chemical and physical changes that occur in glycerol as a result of fast-atom bombardment were determined from accurate mass measurements and tandem mass spectrometry (Chapter 2). Proton transfer to ambient glycerol molecules from the glycerol radical cation and its fragments is proposed to account for bombardment-induced ion formation from neutral glycerol. The products of high-energy (keV) collisions of fullerene radical cations with noble gases, as well as D[sub 2], N[sub 2], NO, and O[sub 2] were investigated by using a three-sector and a four-sector tandem mass spectrometer (Chapter 3). Atomic target gases and D[sub 2] were captured directly, and the various endohedral ([open quotes]in the cage[close quotes]) complexes were observed as product ions. Analysis of the kinetic energies of the product ions produced from He and D[sub 2] collisions leads to the conclusion that the observed product ions from He and D[sub 2] collisions are fragments of the endohedral complexes. Abundant doubly charged product ions were detected in collisions with N[sub 2], NO, and O[sub 2] target gases, and the second ionization energies of the neutral fullerenes were determined from translational energy loss measurements.

  4. Molecular secondary particle emission from molecular overlayers under 10 keV Ar + primary ion bombardment

    NASA Astrophysics Data System (ADS)

    Schnieders, A.; Möllers, R.; Benninghoven, A.

    2001-01-01

    In this paper we focus on the matrix dependence of the secondary particle emission of the purine base adenine (C 5H 5N 5) and the aminoacid β-alanine (C 3H 7NO 2) under 10 keV Ar + primary ion bombardment. We compared the secondary neutral and secondary ion yields of these molecules sputtered from UHV-deposited molecular overlayers with varying surface coverages (sub-monolayer up to a multilayer) on various substrate materials (Si, Cu, Ni, Ag, and Au). Furthermore, we determined disappearance cross-sections of adenine and the mean kinetic energy of sputtered neutral adenine molecules. We found that secondary neutral as well as secondary ion yields for a monolayer coverage are higher than those for a multilayer coverage. The yield enhancement depends on the molecule, the substrate material, and the respective secondary particle species observed in the measurement. These results are explained by a simple model involving different matrix effects. Due to the decoupling of desorption and ionization by using laser postionization for the analysis of sputtered neutral molecules, a classification of the matrix effects into a sputter-induced matrix effect and an ionization matrix effect was possible. Whereas a sputter-induced matrix effect is found for the secondary particle emission of both molecules, adenine and β-alanine, only the secondary ion emission of β-alanine is affected by an ionization matrix effect.

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

    NASA Astrophysics Data System (ADS)

    Maté, 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.

  6. Chemical effects in TiO2 and titanates due to bombardment with Ar+ and O{2/+} ions of different energies (3.5-10 keV)

    NASA Astrophysics Data System (ADS)

    Leinen, D.; Fernández, A.; Espinós, J. P.; González-Elipe, A. R.

    1996-09-01

    Compositional and chemical changes in TiO2 and Ph, Ni, Al and Ba titanates induced by bombardment with Ar+ and O{2/+} ons of different energies have been studied quantitatively by XPS. An increase of preferential loss of oxygen and, in case of PbTiO3, of lead has been observed when increasing the Ar+ ion energy from 3.5 to 10 keV. Because of oxygen loss, Ti4+ species reduce to Ti3+ and Ti2+. In addition, the loss of oxygen from PbTiO3 and NiTiO3 leads to the metallic state of nickel and lead, whereas aluminium and barium in Al2TiO5 and BaTiO3 maintain their chemical state (i.e., Al3+ and Ba2+). Bombardment with OZ ions of PbTiO3 and NiTiO3 leads to a partial reduction of Pb and Ni. This metallization and the preferential loss of lead are more efficient at higher ion energies for both, O{2/+} and Ar+ bombardment. The results are discussed in terms of chemical stabilities and the possibility of oxygen diffusion in the bombarded oxides.

  7. 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.

  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. 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.

  10. Electron and ion emission from surfaces bombarded with large molecular ions (10-100 kDa) at keV energies.

    SciTech Connect

    Ens, W.

    1994-12-31

    Collisions of polyatomic ions with surfaces play an important role in mass spectrometry; they may be involved in ion detection, ion production or ion dissociation. In particular, with the dramatically increased mass range available in mass spectrometry (now several hundred kDa), detection of large (low velocity) molecular ions has become an important problem. The authors have studied secondary ion and electron emission from a variety of surfaces in a tandem time-of-flight mass spectrometer using large molecular ions with energies in the range 1.0 - 30 keV and masses from 276 Da to 113 kDa, produced by matrix-assisted laser desorption. Both ion and electron emission occur for specific energies (velocities) as low as 0.1 eV/Da, well below the predicted threshold for kinetic emission of electrons. Below about 1 eV/Da ion emission is more likely than electron emission. The efficiency of electron or ion production for incident high mass ions at 30 keV is surprisingly high (tens of per cent); presumably the low velocity is compensated by the large number of atoms in the projectile.

  11. The Fullerenes

    NASA Astrophysics Data System (ADS)

    Kroto, H. W.; Walton, D. R. M.

    1993-09-01

    1. The evolution of the football structure for the C60 molecule: a retrospective E. Osawa; 2. Dreams in a charcoal fire: predictions about giant fullerenes and graphite nanotubes D. E. H. Jones; 3. On the formation of the fullerenes R. F. Curl; 4. Production and discovery of fullerites: new forms of crystalline carbon W. Kratschmer and D. R. Huffman; 5. Systematics of fullerenes and related clusters P. W. Fowler; 6. The fullerenes: powerful carbon-based electron acceptors R. C. Haddon; 7. The carbon-bearing material in the outflows from luminous carbon-rich stars M. Jura; 8. Elemental carbon as interstellar dust C. T. Pillinger; 9. The pattern of additions to fullerenes R. Taylor; 10. Polyynes and the formation of fullerenes H. W. Kroto and D. R. M. Walton; 11. Hypothetical graphite structures with negative gaussian curvature A. L. Mackay and H. Terrones; 12. Fullerenes as an example of basic research in industry E. Wasserman; 13. Deltahedral views of fullerene polymorphism D. L. D. Caspar; 14. Geodesic domes and fullerenes.

  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. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M.

    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.

  15. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M.

    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.

  16. Observation of radioactive fullerene families labeled with {sup 11}C

    SciTech Connect

    Ohtsuki, Tsutomu; Masumoto, Kazuyoshi; Sueki, Keisuke; Kobayshi, Kanako; Kikuchi, Koichi

    1995-12-27

    Here, we demonstrate the observation of radioactive fullerenes labeled with {sup 11}C which were produced by photonuclear reaction, namely, {sup 12}C/({gamma},n){sup 11}C ({sup 11}C nuclide decays to {sup 11}B with a half-life of 20.4 min and emits a 511 KeV annihilation {gamma}-ray for {beta}{sup +} decay). These observations are of great interest because they indicate that the carbon network of a fullerene can survive the recoil energy when {sup 11}C is produced by nuclear reaction. This gives us a simple means for producing radioactive fullerene molecules, opening up not only new questions in basic science but also new applications, such as radioactive tracers for nuclear medicine and other fields. In conclusion, experimental evidence seems to show that radioactive C{sub 60} and C{sub 70} fullerenes and products, such as fullerene dimers labeled with {sup 11}C, have been isolated and detected in a liquid phase by radiochromatography. These species were produced by a photonuclear reaction. The {sup 11}C nuclide exists in fullerenes to the extent of about 60-70% of the total amount of {sup 11}C produced when the C{sup 60} sample was irradiated, but at about 20% of the total {sup 11}C when C{sub 70} was irradiated. This successful production of fullerenes labeled with {sup 11}C demonstrates the structural stability and/or flexibility of fullerene cages. 13 refs., 3 figs.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Stability of C60 and C70 fullerenes toward corpuscular and γ radiation

    NASA Astrophysics Data System (ADS)

    Cataldo, Franco; Strazzulla, Giovanni; Iglesias-Groth, Susana

    2009-04-01

    The stability of C60 and C70 fullerenes in the interstellar medium deposited on dust surface or embedded in meteorites and comets has been simulated with γ irradiation and with He+ ion bombardment. It is shown by vibrational spectroscopy that a γ radiation dose of 2.6MGy (1Gy = 1 joule absorbed energy per kilogram) causes partial oligomerization of both C60 and C70 fullerenes. Oligomers are made by fullerene cages chemically connected each other which can yield back free fullerenes by a thermal treatment. The amount of irreversibly polymerized fullerenes caused by 2.6MGy as deduced as the toluene insoluble fraction has been determined as 1.7 and 15 per cent by weight, respectively, for C60 and C70 fullerene. The radiation dose generated by radionuclides decay and expected to be delivered to fullerenes buried at a depth of more than 20m in comets and meteorites is about 3MGy per 109yr. Since fullerenes are by far resistant to such radiation dose they can survive for at least some billion years inside comets and meteorites and in fact have been detected inside certain carbonaceous chondrites. On the other hand, the direct exposure of fullerenes to cosmic rays for instance when they are adsorbed or deposited on the surface of carbon dust corresponds to the delivery of a radiation dose comprised between 30 and 65MGy per 109yr. Experimental bombardment of both C60 and C70 fullerenes for instance with He+ ions has shown that the complete amorphization occurs at about 250MGy. Thus in ~4 Gyr exposure to cosmic rays it is expected a complete amorphization.

  2. Information Entropy of Fullerenes.

    PubMed

    Sabirov, Denis Sh; Ōsawa, 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

  3. Dynamic behavior of thermionic dispenser cathodes under ion bombardment

    NASA Astrophysics Data System (ADS)

    Cortenraad, R.; van der Gon, A. W. Denier; Brongersma, H. H.; Gärtner, G.; Raasch, D.; Manenschijn, A.

    2001-04-01

    We have investigated the surface coverage and electron emission of thermionic dispenser cathodes during 3 keV Ar+ ion bombardment, thereby simulating the bombardment of the cathodes by residual gases that takes place in cathode-ray tubes as used in television sets. During the ion bombardment at the operating temperature of 1030 °C, a dynamic equilibrium is established between the sputter removal and resupply mechanisms of the Ba and O atoms that form the dipole layer on the cathode substrate. We demonstrated that the performance of the cathodes under ion bombardment is governed by the O removal and resupply rates. It was found that the Ba resupply rate is almost an order of magnitude higher than the O resupply rate, but that the Ba can only be present on the surface bound to O atoms. Therefore, the Ba/O ratio is approximately equal to unity during the ion bombardment. Based on the investigations of the removal and resupply processes, we proposed a model that accurately describes the surface coverage and electron emission during the ion bombardment, including the dependence of the ion flux and cathode temperature.

  4. Medicinal applications of fullerenes

    PubMed Central

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

  5. 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)

  6. Synthesis of doped fullerenes

    SciTech Connect

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

    1996-12-31

    The Smalley-Haufler method of laser ablation of graphite mixed with other elements in a heated ({approximately} 1000{degrees}C) rare gas is employed to generate doped fullerenes (e.g., C{sub 56}B{sub 4}) and endohedral fullerenes (e.g., La@C{sub 60}). Laser ablation of graphite in heated nitrogen gas produces C{sub 59} N and C{sub 69} N dimers as evidence by laser desorption mass spectral studies showing C{sub 59}N{sup +} and C{sub 69}N{sup +} ions. Laser ablation of boron nitride yields elemental boron, BN tubules and BN nested fullerenes.

  7. Process for fullerene functionalization

    DOEpatents

    Cahill, Paul A.; Henderson, Craig C.

    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.

  8. 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.

  9. 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.

  10. 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.

  11. Conversion of fullerenes to diamonds

    DOEpatents

    Gruen, Dieter M.

    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.

  12. Conversion of fullerenes to diamond

    DOEpatents

    Gruen, Dieter M.

    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.

  13. 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.

  14. 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

  15. Fullerene formation and annealing

    SciTech Connect

    Mintmire, J.W.

    1996-04-05

    Why does the highly symmetric carbon cluster C{sub 60} form in such profusion under the right conditions? This question was first asked in 1985, when Kroto suggested that the predominance of the C{sub 60} carbon clusters observed in the molecular beam experiments could be explained by the truncated icosahedral (or soccer ball) form. The name given to this cluster, buckminsterfullerene, led to the use of the term fullerenes for the family of hollow-cage carbon clusters made up of even numbers of triply coordinated carbons arranged with 12 pentagonal rings and an almost arbitrary number of hexagonal rings. More than a decade later, we still lack a completely satisfying understanding of the fundamental chemistry that takes place during fullerene formation. Most current models for fullerene formation require a facile mechanism for ring rearrangement in the fullerene structure, but the simplest proposed mechanisms are believed to have unrealistically high activation barriers. In recent research calculations have suggested that atomic carbon in the reaction mixture could act as a catalyst and allow substantially lower activation barriers for fullerene annealing. This article discusses the background for this research and other adjunct research. 14 refs.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Diamond film growth from fullerene precursors

    DOEpatents

    Gruen, Dieter M.; Liu, Shengzhong; Krauss, Alan R.; Pan, Xianzheng

    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.

  8. 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.

  9. 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

  10. XPS study of Si bombarded with low-energy reactive ions

    NASA Astrophysics Data System (ADS)

    Hiroyuki, Yamamoto; Baba, Y.; Sasaki, T. A.

    1993-04-01

    Surface atomic composition and chemical state have been investigated for Si(100) bombarded with 5-keV ions of the second period elements in the periodic table. The XPS observations revealed that the surface chemical changes can be divided into three types, i.e., (1) formation of a thin layer composed of the implanted atoms (B +, C +), (2) formation of new compounds between silicon and the bombarding ions (N +, O +), and (3) no chemical change (F +, Ne +). These changes are discussed in connection with irradiation-induced surface segregation of the implanted atoms and thermochemical stability of the Si compounds formed on the target surface.

  11. 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.

  12. 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.

  13. 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}.

  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. 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.

  16. 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.

  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. 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.

  19. 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

  20. Molecular ion emission from alkanethiol-SAMs by HCI bombardment

    NASA Astrophysics Data System (ADS)

    Flores, Marcos; Esaulov, Vladimir; Yamazaki, Yasunori

    2011-06-01

    In this work, we employ highly charged ions to study the sputtering of positive molecular fragments from two different alkanethiol self-assembled monolayers (SAMs) on gold surfaces: undecanethiol and dodecanethiol. The SAMs are bombarded with a pulsed Arq+ beam (3keV. The desorbed positive molecular ions were detected and analyzed from time-of-flight spectra, and thereby the masses and yields of secondary ions were obtained. The proton yields are dependent on the charge state of the incident ion. On the other hand, the positive molecular ion yields, such as CnHm+, are charge state independent. The positive molecular ion yields decay with the molecular size n.

  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. 30 years of cosmic fullerenes

    NASA Astrophysics Data System (ADS)

    Berné, 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.

  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. Electron bombardment improves vacuum chamber efficiency

    NASA Technical Reports Server (NTRS)

    Przybyszewski, J.; Swiker, M. A.; Watson, J.

    1965-01-01

    Bombardment of vacuum chamber walls by an electron gun within the chamber achieves greater efficiency with less cost. The ultimate vacuum reached using the gun is greater than the system design level.

  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. Superconductivity in doped fullerenes

    SciTech Connect

    Hebard, A.F. )

    1992-11-01

    While there is not complete agreement on the microscopic mechanism of superconductivity in alkali-metal-doped C[sub 60], further research may well lead to the production of analogous materials that lose resistance at even higher temperatures. Carbon 60 is a fascinating and arrestingly beautiful molecule. With 12 pentagonal and 20 hexagonal faces symmetrically arrayed in a soccer-ball-like structure that belongs to the icosahedral point group, I[sub h], its high symmetry alone invites special attention. The publication in September 1990 of a simple technique for manufacturing and concentrating macroscopic amounts of this new form of carbon announced to the scientific community that enabling technology had arrived. Macroscopic amounts of C[sub 60] (and the higher fullerenes, such as C[sub 70] and C[sub 84]) can now be made with an apparatus as simple as an arc furnace powered with an arc welding supply. Accordingly, chemists, physicists and materials scientists have joined forces in an explosion of effort to explore the properties of this unusual molecular building block. 23 refs., 6 figs.

  7. 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.

  8. 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.

  9. Inorganic Fullerenes, Onions, and Tubes

    NASA Astrophysics Data System (ADS)

    York, Andrew P. E.

    2004-05-01

    Since the exciting and unexpected discovery of the soccerball-shaped Buckminsterfullerene (C 60 ) molecule almost two decades ago, great advances in fullerene research have been made. This includes the discovery of inorganic, noncarbon cage and nanotube structures. Of particular interest are the molybdenum and tungsten sulfides and selenides that, when viewed under an electron microscope, are remarkably similar in appearance to the more famous carbon cages and nanotubes. Among other materials capable of forming fullerene structures, nickel chloride is of importance owing to its potential nanoscale magnetic properties, while the synthesis of pure boron nitride fullerenes, with their fascinating structures, was a particular challenge. All of these materials are able to form closed cages as a result of their sheetlike structure, which can, under the right conditions, curl around and either join with an opposite edge to form a tube or roll up into a scroll. Capping of the structures is possible owing to bends in the sheets caused by the inclusion of defects: pentagons for carbon, squares and octagons for boron nitride, and triangular defects for the sulfides. Proposed applications for the inorganic fullerenes include electronic devices and storage media, probes and electron microscope tips, and nano-ball bearings and high temperature lubricants.

  10. 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.

  11. 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...

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Molecular dynamics simulation of bipartite bimetallic clusters under low-energy argon ion bombardment

    NASA Astrophysics Data System (ADS)

    Shirokorad, D. V.; Kornich, G. V.; Buga, S. G.

    2016-02-01

    The evolution of bipartite bimetallic atomic clusters within 5 ps under bombardment with monoenergetic argon ions at the initial energy ranging from 1 eV to 1.4 keV has been simulated by the classical molecular dynamics method with a target obtained from Ni‒Al and Cu‒Au clusters consisting of 78 and 390 atoms, equally divided between the corresponding monometallic parts, the simulated pairs of which have different heats of intermixing. The changes in the potential energy and temperature, the sputtering yields, and the intensity of the ion-stimulated movement of atoms at the interface of the monometallic parts of clusters of both sizes have been determined as functions of the energy of the bombardment.

  1. 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.

  2. FULLERENES AND PROTO-FULLERENES IN INTERSTELLAR CARBON DUST

    SciTech Connect

    Duley, W. W.; Hu Anming

    2012-01-20

    Laboratory spectra of hydrogenated amorphous carbon (HAC) particles prepared under a variety of conditions show spectral features at 7.05, 8.5, 17.4, and 18.9 {mu}m (1418, 1176, 575, and 529 cm{sup -1}) that have been associated with emission from C{sub 60} molecules. These lines occur in the spectra even though C{sub 60} molecules as such are not present in our samples. It appears that these four spectral lines in HAC can instead be associated with precursor molecules or 'proto-fullerenes' (PFs) that subsequently react to yield C{sub 60}. We develop a model tracing the evolution and de-hydrogenation of HAC dust and show that the observation of an emission feature at 16.4 {mu}m (610 cm{sup -1}) in astronomical spectra signals the presence of the pentagonal carbon rings required for the formation of fullerenes. We suggest that the set of four IR emission lines previously identified with C{sub 60} in many objects that also show the 16.4 {mu}m feature and other polycyclic aromatic hydrocarbon bands arise from PFs rather than C{sub 60}. Tc1 is an example of a source in which de-hydrogenation has proceeded to the point where only fullerenes are present.

  3. 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.

  4. Photophysics of fullerenes: Thermionic emission

    SciTech Connect

    Compton, R.N. |; Tuinman, A.A.; Huang, J.

    1996-09-01

    Multiphoton ionization of fullerenes using long-pulse length lasers occurs mainly through vibrational autoionization. In many cases the laser ionization can be described as thermionic in analogy to the boiling off of electrons from a filament. Thermionic emission manifests itself as a delayed emission of electrons following pulsed laser excitation. Klots has employed quasiequilibrium theory to calculate rate constants for thermionic emission from fullerenes which seem to quantitatively account for the observed delayed emission times and the measured electron energy distributions. The theory of Klots also accounts for the thermionic emission of C{sub 60} excited by a low power CW Argon Ion laser. Recently Klots and Compton have reviewed the evidence for thermionic emission from small aggregates where mention was also made of experiments designed to determine the effects of externally applied electric fields on thermionic emission rates. The authors have measured the fullerene ion intensity as a function of the applied electric field and normalized this signal to that produced by single photon ionization of an atom in order to correct for all collection efficiency artifacts. The increase in fullerene ion signal relative to that of Cs{sup +} is attributed to field enhanced thermionic emission. From the slope of the Schottky plot they obtain a temperature of approximately 1,000 K. This temperature is comparable to but smaller than that estimated from measurements of the electron kinetic energies. This result for field enhanced thermionic emission is discussed further by Klots and Compton. Thermionic emission from neutral clusters has long been known for autodetachment from highly excited negative ions. Similarly, electron attachment to C{sub 60} in the energy range from 8 to 12 eV results in C{sub 60} anions with lifetimes in the range of microseconds. Quasiequilibrium theory (QET) calculations are in reasonable accord with these measurements.

  5. 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

  6. Hydrogen defects in proton bombarded KCl.

    NASA Technical Reports Server (NTRS)

    Chu, Y. H.; Friauf, R. J.; Zeller, E. J.

    1972-01-01

    Optical absorption bands are observed in the UV and IR proton bombarded potassium chloride at liquid nitrogen temperature. It is demonstrated that the absorption is due to trapped protons, and the largest UV band has been identified with the U center.

  7. Electronic structure calculations of fullerenes and their derivatives

    SciTech Connect

    Cioslowski, J.

    1995-12-31

    This book review the fullerene field from the perspective of a theoretician with emphasis on electronic structure. Topics include the theoretical methods currently used; geometry, vibrational frequencies, heats of formation and ionic and excited states of higher fullerenes; small fullerenes, tubular and polymetirc allotropes of carbon, endohedral complexes; fullerene derivatives and solid-state properties of C60 based materials.

  8. 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

  9. Production of fullerenes with concentrated solar flux

    NASA Astrophysics Data System (ADS)

    Hale, M. J.; Fields, C.; Lewandowski, A.; Bingham, C.; Pitts, R.

    1994-01-01

    Research at the National Renewable Energy Laboratory (NREL) has demonstrated that fullerenes can be produced using highly concentrated sunlight from a solar furnace. Since they were first synthesized in 1989, fullerenes have been the subject of intense research. They show considerable commercial potential in advanced materials and have potential applications that include semiconductors, superconductors, high-performance metals, and medical technologies. The most common fullerene is C60, which is a molecule with a geometry resembling a soccer ball. Graphite vaporization methods such as pulsed-laser vaporization, resistive heating, and carbon arc have been used to produce fullerenes. None of these, however, seems capable of producing fullerenes economically on a large scale. The use of concentrated sunlight may help avoid the scale-up limitations inherent in more established production processes. Recently, researchers at NREL made fullerenes in NREL's 10 kW high flux solar furnace (HFSF) with a vacuum reaction chamber designed to deliver a solar flux of 1200 W/sq cm to a graphite pellet. Analysis of the resulting carbon soot by mass spectrometry and high pressure liquid chromatography confirmed the existence of fullerenes. This paper presents the method, experimental apparatus, and results of fullerene production research performed with the HFSF.

  10. 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.

  11. Fullerenic structures and such structures tethered to carbon materials

    SciTech Connect

    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.

  12. 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.

  13. Functionalization of silicon crystal surface by energetic cluster ion bombardment.

    PubMed

    Lavrentiev, Vasily; Vacik, Jiri; Dejneka, Alexandr; Jastrabik, Lubomir; Vorlicek, Vladimir; Chvostova, Dagmar; Potucek, Zdenek; Narumi, Kazumasa; Naramoto, Hiroshi

    2012-12-01

    We report the creation of a functional nanostructure on a Si crystal surface by 200 keV C60(++) cluster ion bombardment (CIB). We found that the modified layer produced by CIB includes two sublayers with different nanostructures. The top 24-nm-thick sublayer is an agglomeration of 5-nm-sized amorphous Si nanodots (a-Si NDs). The deeper 10-nm-thick sublayer is a transient layer of disordered Si as an interface between the a-Si top sublayer and the bulk Si(100). The top a-Si sublayer and the nc-Si transient layer are formed by the local heating effect and shock wave effect, respectively, induced by the cluster ion impacts. The photoluminescence (PL) spectra of the CIB-modified Si samples revealed an emission line centered at a photon energy of 1.92 eV. The absorption spectra of the modified samples exhibit enhanced light absorption at this photon energy. The parameters of the PL line require ascribing the emission origin to the quantum-confinement-induced optical transitions in the a-Si nanodots. The core-shell structure of a-Si NDs is confirmed by detection of an additional PL line centered at 2.5 eV. Analysis of the Rutherford backscattering (RBS) and the PL spectra implies the existence of -Si--O- bonds in the nanodot outer shells, which are responsible for the additional PL line. The obtained results demonstrate the valuable potential of CIB for the controllable fabrication of Si surface nanostructures, which is attractive for optoelectronics and nanoelectronics. The obtained results elucidate the evolution of structure modification occurring in silicon due to the injection of energetic C60 cluster ions with an energy of hundreds of keV. PMID:23447968

  14. 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.

  15. 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 FcγR- and TNF-α-induced mediator release from MC; TNF-α-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 FcγR-mediated increases in cellular reactive oxygen species and NF-κB 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-α. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Interstellar fullerene compounds and diffuse interstellar bands

    NASA Astrophysics Data System (ADS)

    Omont, Alain

    2016-05-01

    Recently, the presence of fullerenes in the interstellar medium (ISM) has been confirmed and new findings suggest that these fullerenes may possibly form from polycyclic aromatic hydrocarbons (PAHs) in the ISM. Moreover, the first confirmed identification of two strong diffuse interstellar bands (DIBs) with the fullerene, C60+, connects the long standing suggestion that various fullerenes could be DIB carriers. These new discoveries justify reassessing the overall importance of interstellar fullerene compounds, including fullerenes of various sizes with endohedral or exohedral inclusions and heterofullerenes (EEHFs). The phenomenology of fullerene compounds is complex. In addition to fullerene formation in grain shattering, fullerene formation from fully dehydrogenated PAHs in diffuse interstellar clouds could perhaps transform a significant percentage of the tail of low-mass PAH distribution into fullerenes including EEHFs. But many uncertain processes make it extremely difficult to assess their expected abundance, composition and size distribution, except for the substantial abundance measured for C60+. EEHFs share many properties with pure fullerenes, such as C60, as regards stability, formation/destruction and chemical processes, as well as many basic spectral features. Because DIBs are ubiquitous in all lines of sight in the ISM, we address several questions about the interstellar importance of various EEHFs, especially as possible carriers of diffuse interstellar bands. Specifically, we discuss basic interstellar properties and the likely contributions of fullerenes of various sizes and their charged counterparts such as C60+, and then in turn: 1) metallofullerenes; 2) heterofullerenes; 3) fulleranes; 4) fullerene-PAH compounds; 5) H2@C60. From this reassessment of the literature and from combining it with known DIB line identifications, we conclude that the general landscape of interstellar fullerene compounds is probably much richer than heretofore realized. EEHFs, together with pure fullerenes of various sizes, have many properties necessary to be suitably carriers of DIBs: carbonaceous nature; stability and resilience in the harsh conditions of the ISM; existing with various heteroatoms and ionization states; relatively easy formation; few stable isomers; spectral lines in the right spectral range; various and complex energy internal conversion; rich Jahn-Teller fine structure. This is supported by the first identification of a DIB carrier as C60+. Unfortunately, the lack of any precise information about the complex optical spectra of EEHFs and most pure fullerenes other than C60 and about their interstellar abundances still precludes definitive assessment of the importance of fullerene compounds as DIB carriers. Their compounds could significantly contribute to DIBs, but it still seems difficult that they are the only important DIB carriers. Regardless, DIBs appear as the most promising way of tracing the interstellar abundances of various fullerene compounds if the breakthrough in identifying C60+ as a DIB carrier can be extended to more spectral features through systematic studies of their laboratory gas-phase spectroscopy.

  1. 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

  2. Interatomic Electronic Decay in Endohedral Fullerenes

    SciTech Connect

    Averbukh, Vitali; Cederbaum, Lorenz S.

    2006-02-10

    Ionization of an atom X in an endohedral fullerene complex X at C{sub n} can lead to a wealth of nonradiative decay processes. These interatomic processes occur due to the correlation existing between the atomic and the fullerene electrons and do not take place in the free species X. Considering Ne at C{sub 60} as an example, we calculate the rates of the interatomic decay processes and show that the interatomic decay in Ne at C{sub 60} is ultrafast. Moreover, our analysis suggests that interatomic decay in an endohedral fullerene does not necessarily lead to the destruction of the complex.

  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 2.6×2.6 × 1015 ion/cm2 to 8×2.6 × 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 8×2.6 × 1015 ion/cm2 or 9×2.6 × 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 9×2.6 × 1015 ion/cm2 generated several mutant phenotypes which were observed in the 5th instar silkworms and a moth.

  5. Effects of ion and micrometeorite bombardment on mineral surfaces: application to Eros, the Moon, and Mercury

    NASA Astrophysics Data System (ADS)

    Baragiola, R. A.; Loeffler, M. J.; Dukes, C. A.; Chang, W. Y.; Fitz-Gerald, J. M.; McFadden, L. A.

    2004-11-01

    We study in the laboratory the effects of ion and micrometeorite bombardment on mineral surfaces of airless bodies such as asteroids, the Moon, and Mercury. We use 4 keV He and 1 keV H ions to simulate the solar wind and nanosecond laser pulses to simulate micrometeorite impacts. Related to the question of the origin of the Na exospheres around the Moon and Mercury, we studied sputtering of Na from plagioclase feldspars and from Na deposited on olivine and on albite. Chemical characterization of the samples is made by X-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS), secondary ion mass spectrometry (SIMS), and neutral mass spectrometry. We find that ion bombardment depletes Na from the surface of the feldspars but that the Na segregates back to the surface in a few hours at room temperature. Analysis of the removal of sodium adsorbed on the surface of olivine by He ion irradiation gives a sputtering cross section in line with what is expected for knock-on sputtering, and five orders of magnitude larger than for photo-stimulated desorption. We also determined that the energy distribution of the sputtered ions has a peak at a few eV and a long tail to about 50 eV. Regarding the interpretation of NEAR data from Eros we irradiated powders of olivine with nanosecond 248 nm laser pulses and studied reflectance changes in the visible and near-infrared and chemical changes with XPS. We have collected the ejecta on a quartz-crystal microbalance to quantify the amount of ejecta per pulse. The deposit was found to be crystalline olivine. When collected on a fine-grained olivine surface, it produced visible darkening. We will also report on experiments that serve to explain sulfur depletion at Eros by the solar wind and micrometeorite bombardment. Supported by NASA Cosmochemistry and NEAR Data Analysis Programs.

  6. 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).

  7. 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

  8. 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 MαC{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)

  9. 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.}

  10. 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...

  11. 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.

  12. Adsorption of amino acids by fullerenes and fullerene nanowhiskers

    NASA Astrophysics Data System (ADS)

    Hashizume, Hideo; Hirata, Chika; Fujii, Kazuko; Miyazawa, Kun'ichi

    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.

  13. 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.

  14. 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.

  15. Fullerenes in electron cyclotron resonance ion sources

    SciTech Connect

    Biri, S.; Fekete, E.; Kitagawa, A.; Muramatsu, M.; Janossy, A.; Palinkas, J.

    2006-03-15

    Fullerene plasmas and beams have been produced in our electron cyclotron resonance ion sources (ECRIS) originally designed for other purposes. The ATOMKI-ECRIS is a traditional ion source with solenoid mirror coils to generate highly charged ions. The variable frequencies NIRS-KEI-1 and NIRS-KEI-2 are ECR ion sources built from permanent magnets and specialized for the production of carbon beams. The paper summarizes the experiments and results obtained by these facilities with fullerenes. Continuous effort has been made to get the highest C{sub 60} beam intensities. Surprisingly, the best result was obtained by moving the C{sub 60} oven deep inside the plasma chamber, very close to the resonance zone. Record intensity singly and doubly charged fullerene beams were obtained (600 and 1600 nA, respectively) at lower C{sub 60} material consumption. Fullerene derivatives were also produced. We mixed fullerenes with other plasmas (N, Fe) with the aim of making new materials. Nitrogen encapsulated fullerenes (mass: 720+14=734) were successfully produced. In the case of iron, two methods (ferrocene, oven) were tested. Molecules with mass of 720+56=776 were detected in the extracted beam spectra.

  16. Symmetric nested complexes of fullerenes.

    PubMed

    Mar, Naveicy; Sansores, Luis Enrique; Muhl, Stephen; Ramos, Estrella; Salcedo, Roberto

    2015-04-01

    Large fullerenes such as C180 and C116 can be used as hosts for other molecules of the same family. Based on this idea, two complexes were designed, one in which C180 accepts a C60 molecule as a guest and the other in which C20 was placed inside C116. The behavior of these new assemblies was closer to that of a large endohedral complex rather than onion-like. There were marked differences between the systems. In the first system, there was minor interaction between the two cages but the association resulted in a more stable thermodynamic state. In the second system, there was strong electronic interchange between the cages, and the thermodynamic results suggest that such a combination might be useful for forming stable C20. PMID:25823391

  17. 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

  18. 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 Θ. In the general case a capillary constant a⊥(L,Θ) is a convex function of both variables viz. normalized spatial-period L and an angle of incidence Θ. With energy E0=9 keV this function exhibits a local maximum at L=1.77,Θ=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,Θ) 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 Θ=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 Θcin=55∘ when ion energy tends to minimum energy of WOS formation E0=1.5 keV.

  19. 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)

  20. 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.

  1. 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.

  2. 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.

  3. Formation dynamics of fullerene dimers C118+, C119+, and C120+

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Zettergren, H.; Rousseau, P.; Chen, T.; Gatchell, M.; Stockett, M. H.; Domaracka, A.; Adoui, L.; Huber, B. A.; Cederquist, H.; Alcamí, M.; Martín, F.

    2014-06-01

    Dumbbell-shaped fullerene dimers C118+ and C119+ have recently been observed in mass spectra resulting from collisions between clusters of C60 molecules and keV He2+ or Ar2+ ions [H. Zettergren et al., Phys. Rev. Lett. 110, 185501 (2013), 10.1103/PhysRevLett.110.185501 and F. Seitz et al., J. Chem. Phys. 139, 034309 (2013), 10.1063/1.4812790]. To unveil the formation mechanisms of these fullerene dimers, systematic molecular dynamics (MD) simulations based on the self-consistent charge density functional tight-binding method have been performed for Cn+ + C60 (n =58,59,60) collisions following prompt atom knockouts by the fast ions. The statistics from the MD simulations indicate a much higher reactivity of C59+ and C58+ fragments compared to that of C60+. It is found that the covalently bonded dumbbell-shaped fullerene dimers C118+ and C119+ can be formed at very low-collision energies within 1 ps and are stable enough to survive on the microsecond time scale of the experiment. The thermodynamic and kinetic stabilities, as well as the bonding features, have been investigated for the most stable dumbbell dimers C118+, C119+, and C120+.

  4. 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…

  5. 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

  6. Characteristic fragmentation of polysiloxane monolayer films by bombardment with monatomic and polyatomic primary ions in TOF-SIMS.

    PubMed

    Moon, Hye Kyoung; Wells, David D; Gardella, Joseph A

    2012-01-01

    This study reports the characteristic fragmentation patterns from two polysiloxane polymers that form ordered overlayer on silver substrates. Results are compared for the bombardment of various monatomic and polyatomic projectiles of Cs(+), C(60)(+) (10 keV), Bi(1)(+), and Bi(3)(+) (25 keV) in the high mass range time-of-flight secondary ion mass spectrometry (TOF-SIMS) spectra. Results are reported from sub-monolayer (solution cast) coverages of poly(dimethylsiloxane)s with the number average molecular weights (M(n)) of 2200 and 6140 Da, respectively, and Langmuir-Blodgett monolayers of poly(methylphenylsiloxane) with molecular weights (MW) from 600 and 1000 Da. For each film, Bi projectiles resulted in the emission of positive silver cluster ions from the substrate under the polymer overlayer and peaks corresponding to silver cluster ions with larger mass were observed by impact of polyatomic 25 keV Bi(3)(+) projectiles. In addition, depending on the change of energy of Bi (3) (+) , a different pattern of fragments was observed. With Cs(+) and C(60)(+) impact, however, the emission of silver cluster ions was not detected. In the case of C(60)(+) impact for PDMS-6140, peaks corresponding to silver-cationized intact oligomers were not observed. In this paper, these results are explained by the possible bombardment mechanism for each projectile, based on its mass, energy, and split trajectories of the component atoms under the polyatomic impact. PMID:22042500

  7. Characteristic Fragmentation of Polysiloxane Monolayer Films by Bombardment with Monatomic and Polyatomic Primary Ions in TOF-SIMS

    NASA Astrophysics Data System (ADS)

    Moon, Hye Kyoung; Wells, David D.; Gardella, Joseph A.

    2012-01-01

    This study reports the characteristic fragmentation patterns from two polysiloxane polymers that form ordered overlayer on silver substrates. Results are compared for the bombardment of various monatomic and polyatomic projectiles of Cs+, C{60/+} (10 keV), Bi{1/+}, and Bi{3/+} (25 keV) in the high mass range time-of-flight secondary ion mass spectrometry (TOF-SIMS) spectra. Results are reported from sub-monolayer (solution cast) coverages of poly(dimethylsiloxane)s with the number average molecular weights (Mn) of 2200 and 6140 Da, respectively, and Langmuir-Blodgett monolayers of poly(methylphenylsiloxane) with molecular weights (MW) from 600 and 1000 Da. For each film, Bi projectiles resulted in the emission of positive silver cluster ions from the substrate under the polymer overlayer and peaks corresponding to silver cluster ions with larger mass were observed by impact of polyatomic 25 keV Bi{3/+} projectiles. In addition, depending on the change of energy of Bi{3/+}, a different pattern of fragments was observed. With Cs+ and C{60/+} impact, however, the emission of silver cluster ions was not detected. In the case of C{60/+} impact for PDMS-6140, peaks corresponding to silver-cationized intact oligomers were not observed. In this paper, these results are explained by the possible bombardment mechanism for each projectile, based on its mass, energy, and split trajectories of the component atoms under the polyatomic impact.

  8. 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

  9. 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

  10. 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.

  11. Structural evolution in polythiophene-fullerene mixtures

    NASA Astrophysics Data System (ADS)

    Gomez, Enrique; Kozub, Derek; Vakhshouri, Kiarash

    2011-03-01

    The morphology of organic semiconductor mixtures employed as the active layer of organic solar cells is a result of the complex interplay between the crystallinity of the constituents and the chemical incompatibility. Given that device performance can depend critically on the morphology of the active layer, efforts aimed identifying at the critical parameters for the structure formation process are important for the development of high-performance devices. We demonstrate that polythiophene-fullerene mixtures are partially miscible and that the crystallization of the electron donor drives the characteristic length scales of the structure. By modeling fullerene as a solvent for polythiophene, we have estimated the Flory-Huggins interaction parameter from measurements of the melting point depression of polythiophene. The miscibility between poly(3-hexylthiophene) (P3HT) and fullerene at P3HT volume fractions greater than 0.4 leads to a severe suppression of the crystallization of fullerene. Our efforts have enabled us to develop a hypothesis for the structure formation process in polythiophene/fullerene mixtures.

  12. Fullerene (C60) films for solid lubrication

    SciTech Connect

    Bhushan, B.; Gupta, B.K.; Van Cleef, G.W.; Capp, C.E.; Coe, J.V. )

    1993-10-01

    The advent of techniques for producing gram quantities of a new form of stable, pure, solid carbon, designated as fullerene, opens a profusion of possibilities to be explored in many disciplines including tribology. Fullerenes take the form of hollow geodesic domes, which are formed from a network of pentagons and hexagons with covalently bonded carbon atoms. The C60 molecule has the highest possible symmetry (icosahedral) and assumes the shape of a soccer ball. At room temperature, fullerene molecules pack in an fcc lattice bonded with weak van der Waals attractions. Fullerenes can be dissolved in solvents such as toluene and benzene and are easily sublimed. The low surface energy, high chemical stability, spherical shape, weak intermolecular bonding, and high load bearing capacity of C60 molecules offer potential for various mechanical and tribological applications. This paper describes the crystal structure and properties of fullerenes and proposes a mechanism for self-lubricating action. Sublimed films of C60 have been produced and friction and wear performance of these films in various operating environments are the subject of this paper. The results of this study indicate that C60, owing to its unique crystal structure and bonding, may be a promising solid lubricant. 31 refs.

  13. Energetics of water permeation through fullerene membrane

    PubMed Central

    Isobe, Hiroyuki; Homma, Tatsuya; Nakamura, Eiichi

    2007-01-01

    Lipid bilayer membranes are important as fundamental structures in biology and possess characteristic water-permeability, stability, and mechanical properties. Water permeation through a lipid bilayer membrane occurs readily, and more readily at higher temperature, which is largely due to an enthalpy cost of the liquid-to-gas phase transition of water. A fullerene bilayer membrane formed by dissolution of a water-soluble fullerene, Ph5C60K, has now been shown to possess properties entirely different from those of the lipid membranes. The fullerene membrane is several orders of magnitude less permeable to water than a lipid membrane, and the permeability decreases at higher temperature. Water permeation is burdened by a very large entropy loss and may be favored slightly by an enthalpy gain, which is contrary to the energetics observed for the lipid membrane. We ascribe this energetics to favorable interactions of water molecules to the surface of the fullerene molecules as they pass through the clefts of the rigid fullerene bilayer. The findings provide possibilities of membrane design in science and technology. PMID:17846427

  14. Investigations on the effect of argon ion bombardment on the structural and optical properties of crystalline gallium antimonide

    NASA Astrophysics Data System (ADS)

    Pandey, S. D.; Dubey, S. K.; Dubey, R. L.; Yadav, A. D.; Gupta, S. J.; Gokhale, M. R.; Arora, B. M.

    2006-07-01

    The effects of bombardment of 250 keV argon ions in n-type GaSb at fluences 2x10(15) and 5x10(15) ions cm(-2) were investigated by high-resolution X-ray diffraction (HRXRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). HRXRD studies revealed the presence of radiation-damaged layer (strained) peak in addition to the substrate peak. The variation in the lattice constant indicates the strain in the bombarded region. The out-of-plane (epsilon(perpendicular to)) and in-plane strains (epsilon(parallel to)) determined from the profiles of several symmetric and asymmetric Bragg reflections, respectively, were found to change with the ion fluence. Simulations of XRD patterns using dynamical theory of X-ray scattering (single-layer model) for the damaged layer yielded good fits to the recorded profiles. FTIR transmission studies showed that the optical density (alpha center dot d) of GaSb bombarded with different fluences increases near the band edge with increase in ion fluence, indicating the increase in the defect concentration. The density of the defects in the samples bombarded with different fluences was in the range of 3.20x10(21)-3.80x10(21) cm(-3) . The tailing energy estimated from the transmission spectra was found to change from 12.0 to 58.0 meV with increasing ion fluences, indicating the decrease of crystallinity at higher fluences. SEM micrographs showed the swelling of the bombarded surface of about 0.33 mu m for the fluence of 2x10(15) ions cm(-2) , which increased to 0.57 mu m for the fluence of 5x10(15) ions cm(-2) .

  15. Kinetic Stability of Non-IPR Fullerene Molecular Ions.

    PubMed

    Aihara, Jun-ichi; Nakagami, Yuto; Sekine, Rika

    2015-06-18

    Many fullerenes that violate the isolated pentagon rule (IPR) form stable metallofullerenes. In general, a fullerene cage is kinetically stabilized by acquiring a given number of electrons. Kinetic stability of negatively charged non-IPR fullerenes, including the recently isolated endohedral metallofullerene with a heptagonal face, was rationalized in terms of bond resonance energy (BRE). Interestingly, molecular anions of conventional fullerenes found in most isolated metallofullerenes are kinetically stable with large positive BREs for all CC bonds. As we pointed out in 1993, the IPR does not apply to charged fullerenes because π-bonds shared by two five-membered rings are aromatized to varying extents. PMID:26020361

  16. 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.

  17. Production of fullerenes using concentrated solar flux

    DOEpatents

    Fields, Clark L.; Pitts, John Roland; King, David E.; Hale, Mary Jane; Bingham, Carl E.; Lewandowski, Allan A.

    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.

  18. Characterization of Hydrogenated Fullerenes by NMR Spectroscopy

    NASA Astrophysics Data System (ADS)

    Hedenström, Mattias; Wågberg, Thomas; Johnels, Dan

    NMR spectroscopy is so far the only analytical technique that has been used to get a detailed structural characterization of hydrogenated fullerenes. A substantial amount of information derived from different NMR experiments can thus be found in the literature for a number of fullerenes hydrogenated to various degrees. These studies have benefitted from the fact that chemical shifts of 1H and 13C and in some cases also 3He can be used to obtain structural information of these compounds. Such results, together with discussions about different NMR experiments and general considerations regarding sample preparations, are summarized in this chapter. The unique information, both structural and physicochemical, that can be derived from different NMR experiments ensures that this technique will continue to be of central importance in characterization of hydrogenated fullerenes.

  19. Passive optical switches based on endohedral fullerenes

    NASA Astrophysics Data System (ADS)

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

    Although there have been many attempts to find better nanomaterial-based optical limiters & switches in recent years, currently there are only a few effective options for high-energy lasers. Reverse saturable absorption in fullerenes has been widely used to realize excellent passive optical limiters for the visible region up to 650 nm. The electronic structure of fullerenes can be modified by the encapsulation of endohedral clusters to achieve exotic quantum states of matter such as superconductivity. Building on this concept, in this talk, we show that three tri-metallic nitride endohedral fullerenes could alter the HOMO-LUMO gap and allow passive optical switching with a low limiting threshold (0.3 J/cm2) and a wider operation window up to 1064 nm (average pulse energy>0.5 mJ in ns regime).

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Electronic structures of fullerene derivatives and endohedral complexes

    SciTech Connect

    Raghavachari, K.

    1993-12-31

    Chemical modifications of fullerenes have resulted in the formation of a variety of functionalized fullerenes. In this work, the authors investigate the structures and properties of fullerene derivatives by means of semiempirical, ab initio Hartree-Fock, and density functional studies. Covalently bonded fullerene derivatives such as C{sub 60}O, C{sub 70}O, C{sub 60}CH{sub 2}, C{sub 60}, C(CH{sub 3}){sub 2}, C{sub 60}C(C{sub 6}H{sub 5}){sub 2}, etc. are considered in detail. The bonding in the derivatized fullerenes is compared to that in C{sub 60}. Spectroscopic properties and chemical reactivities of the derivatives are discussed. Endohedral complexes derived from the fullerenes C{sub 60}-C{sub 84} are also investigated. The electronic structures of the fullerenes which lead to stable endohedral complexes are analyzed.

  5. 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

  6. 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

  7. 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.

  8. Effective defect diffusion lengths in Ar-ion bombarded 3C-SiC

    NASA Astrophysics Data System (ADS)

    Bayu Aji, L. B.; Wallace, J. B.; Shao, L.; Kucheyev, S. O.

    2016-05-01

    Above room temperature, SiC exhibits pronounced processes of diffusion and interaction of radiation-generated point defects. Here, we use the recently developed pulsed ion beam method to measure effective defect diffusion lengths in 3C-SiC bombarded in the temperature range of 25–200 °C with 500 keV Ar ions. Results reveal a diffusion length of  ∼10 nm, which exhibits a weak temperature dependence, changing from 9 to 13 nm with increasing temperature. These results have important implications for understanding and predicting radiation damage in SiC and for the development of radiation-resistant materials via interface-mediated defect reactions.

  9. 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.

  10. Photon emission produced by Kr+ ions bombardment of Cr and Cr2O3 targets

    NASA Astrophysics Data System (ADS)

    Boujlaidi, A. El; Hammoum, K.; Jadoual, L.; Jourdani, R.; Ait El Fqih, M.; Aouchiche, H.; Kaddouri, A.

    2015-01-01

    The sputter induced photon spectroscopy technique was used to study the luminescence spectra of the species sputtered from chromium powder and its oxide Cr2O3, during 5 keV Kr+ ions bombardment in vacuum better than 10-7 torr. The optical spectra recorded between 350 and 470 nm exhibit discrete lines which are attributed to neutral excited atoms of chromium (Cr I lines). The experiments are also performed under 10-5 torr ultra pure oxygen partial pressure. The results demonstrate that the measured intensities of the emitted photons are always higher in the presence of oxygen and even higher than those obtained for Cr2O3 target. In the presence of oxygen vapor we assume that an oxide film is formed on the chromium surface which is responsible of the increase of photon emission. This variation in the intensities is correctly explained in the model of electron transfer processes between the excited sputtered atom and the bombarded surface. This model suggests that the structure formed on the Cr surface in the case of oxygenated chromium is closer to that of Cr2O3 oxide.

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

    NASA Astrophysics Data System (ADS)

    Bielinski, D. M.; Jagielski, J.; Lipinski, P.; Pieczynska, D.; Ostaszewska, U.; Piatkowska, A.

    2009-03-01

    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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. PAH bombardment by energetic particles: models and astrophysical implications

    NASA Astrophysics Data System (ADS)

    Micelotta, E.; Jones, A.; Tielens, A.

    2011-05-01

    Polycyclic Aromatic Hydrocarbons (PAHs) are an important and ubiquitous component of the Interstellar Medium (ISM) of galaxies. Interstellar PAHs are apparently able to withstand the rigors of the harsh environment of the ISM for some some 100 million years and thus are resilient against processing by UV and X-ray photons and supernova shock waves. PAHs in space are mainly studied through their characteristic emission bands, due to infrared fluorescence following the absorption of UV photons. This is the reason why the photophysics of PAHs in space has been extensively investigated. On the other hand, PAHs are also strongly affected by collisional processes, i.e. bombardment by high-velocity ions and electrons, arising from interstellar shocks, hot gas and cosmic rays. However, very little was known about the physics of the interaction between PAHs and high energy particles, especially in terms of PAH damage and destruction. This lack of information had made the interpretation of PAH observations difficult in regions subjected to such processes. Our research aims to fill this key gap in our understanding of the physics behind collisional processing of PAHs and to clarify how this affects the PAH evolution in the astrophysical context. We first describe the models we have developed, that take into account the molecular nature of the target PAH and allow for the first time a quantitative description of the collisional processing of PAH molecules by ions and electrons with energies between 10 eV and 10 keV (in shocks and hot gas) and between 5 MeV and 10 GeV (in cosmic rays). Specific models were needed because PAHs are molecules and not small solid fragments, thus the classical approach from solid state physics cannot be applied. We then show the applications of our models to observations, estimating the lifetime of PAHs against collisional processing in specific objects. We discuss the astrophysical implications of our findings on the considered sample, which includes very different objects such as supernova remnants, normal/starburst galaxies and galaxy clusters.

  18. Leak decay method of helium bombardment leak testing

    NASA Technical Reports Server (NTRS)

    Garton, W. P.

    1972-01-01

    Method for verifying hermetic seal quality of small components is described. Procedure for using helium bombardment and examination with mass spectrometer is described. Technique eliminates errors in seal quality determination and checks quality of seals without contaminating products.

  19. 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.

  20. 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.

  1. Effect of xenon bombardment on ruthenium-coated grazing incidence collector mirror lifetime for extreme ultraviolet lithography

    SciTech Connect

    Nieto, Martin; Allain, Jean-Paul; Titov, Vladimir; Hendricks, Matthew R.; Hassanein, Ahmed; Rokusek, Daniel; Chrobak, Christopher; Tarrio, Charles; Barad, Yaniv; Grantham, Steven; Lucatorto, Thomas B.; Rice, Brian

    2006-09-01

    The effect of energetic xenon ion bombardment on the extreme ultraviolet (EUV) reflectivity performance of mirrors is of vital importance for the performance of discharge- and laser-produced plasma extreme ultraviolet lithography sources. To study these effects, we measured absolute and relative reflectivities at the National Institute of Standards and Technology and the Interaction of Materials with Particles and Components Testing facility to quantify the effects of singly ionized Xe ion bombardment on the reflectivity of Ru EUV collector mirrors. Results show that unity sputtering is reached at Xe{sup +} energies near 400-500 eV. The Xe{sup +}-induced sputter yield decreases an order of magnitude with only a 60% decrease in energy. Incident angle-dependent data of Xe{sup +} bombardment show that the sputter yield is weakly dependent on angle at energies near 1 keV. Dynamic measurements of in situ EUV reflectivity during Xe{sup +} irradiation show that the oxygen state of the reflecting mirror has a significant effect on reflectivity performance. For example, 13.5 nm light reflecting from an oxygen-rich mirror results in over a 40% loss in reflectivity. These studies also found that the surface roughness increased only at the atomic scale (subnanometer scale) when exposed to energetic Xe{sup +} and thus did not contribute to EUV reflectivity losses except for cases of very high fluences (>10{sup 16} cm{sup -2})

  2. 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.

  3. a Study of Sputtering from Thin Films with 175 -190 KEV Argon Ions.

    NASA Astrophysics Data System (ADS)

    de Vincenz, Andre Michael

    1987-09-01

    Titanium, copper and gold thin films, of various thicknesses, on aluminum backing, have been bombarded with 175 keV and 186 keV Ar^+ ions, and the respective sputtering yields have been determined. The energetic ions were produced in a 400 keV Van de Graaff accelerator, and uniform ion irradiation of the samples was obtained by sweeping the ion beam across the target. The technique used to determine the "effective" ion dose responsible for film sputtering was based on the integration of the function representing the intensity of the ion-induced optical emission from substrate normalized twice: with respect to the beam current intensity and with respect to its own final value after the complete erosion of the film. The amount of film material removed by sputtering was determined by in-situ proton PIXE. In the thick-target limit, the values obtained for the sputter yield in all cases agree with published data and theoretical predictions. For films thinner than one full ion-range, the sputtering yield is a function of film thickness. In addition, it was possible to determine the partial sputter yield for Ti implanted in Al substrate. Also, the ion-induced K X-ray lines from Ti and Cu targets, and the M group of lines from Au have been observed. These lines, when compared with those produced by proton bombardment, are broader, have significantly smaller production cross section and their energies are shifted toward higher values. No Ar_+ ion-induced L X-ray lines from Au have been observed.

  4. 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.

  5. 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.

  6. Synthesis of Endohedral Fullerene Using ECR Ion Source

    SciTech Connect

    Minezaki, Hidekazu; Uchida, Takashi; Tanaka, Kiyokatsu; Asaji, Toyohisa; Muramatsu, Masayuki; Kitagawa, Atsushi; Kato, Yushi; Racz, Richard; Biri, Sandor; Yoshida, Yoshikazu

    2011-01-07

    We are developing an ECRIS apparatus which is designed for the production of endohedral fullerenes. Our promising approaches to produce the endohedral fullerenes using the ECRIS are the ion-ion collision reaction of fullerenes and the other atom in their mixture plasma and simple ion implantation of atom into fullerene layer. In this study, we tried to synthesize the endohedral nitrogen-fullerenes by ion implantation. N{sup +} beam was irradiated to a fullerene target with a specific energy and dose. As a result, we could observe the peak of N+C{sub 60} from targets after N{sup +} beam irradiation with TOF-SIMS and LDI-TOF-MS.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. A search for hydrogenated fullerenes in fullerene-containing planetary nebulae

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    Detections of C60 and C70 fullerenes in planetary nebulae (PNe) of the Magellanic Clouds and of our own Galaxy have raised the idea that other forms of carbon, such as hydrogenated fullerenes (fulleranes like C60H36 and C60H18), buckyonions, and carbon nanotubes, may be widespread in the Universe. Here we present VLT/ISAAC spectra (R ~ 600) in the 2.9-4.1 μm spectral region for the Galactic PNe Tc 1 and M 1-20, which have been used to search for fullerene-based molecules in their fullerene-rich circumstellar environments. We report the non-detection of the most intense infrared bands of several fulleranes around ~3.4-3.6 μm in both PNe. We conclude that if fulleranes are present in the fullerene-containing circumstellar environments of these PNe, then they seem to be much less abundant than C60 and C70. Our non-detections, together with the (tentative) fulleranes detection in the proto-PN IRAS 01005+7910, suggest that fulleranes may be formed in the short transition phase between AGB stars and PNe, but they are quickly destroyed by the UV radiation field from the central star.

  14. Solubility of Fullerenes in Fatty Acids Esters: A New Way to Deliver In Vivo Fullerenes. Theoretical Calculations and Experimental Results

    NASA Astrophysics Data System (ADS)

    Cataldo, Franco

    The biological effects of fullerenes and, in particular, of C60 have been recognized since long time. One of the problems which hindered the application of fullerenes in medicinal chemistry regards their insolubility in water and water-based fluids. In the present chapter it is reported that C60 and C70 fullerenes are soluble in vegetable oils, in general, in esters of fatty acids and in free fatty acids. These results pave the way in the utilization of vegetable oils as vehicles in the delivery of fullerenes for both topical applications and internal use (e.g., intramuscular injection).

  15. 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.

  16. 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.

  17. 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 μg mL−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

  18. Three-Dimensional Metal-Fullerene Frameworks.

    PubMed

    Kraft, Andreas; Roth, Patrick; Schmidt, David; Stangl, Johannes; Müller-Buschbaum, Klaus; Beuerle, Florian

    2016-04-18

    Hexakis-substituted [60]fullerene adducts with icosahedral symmetry provide an unprecedented scaffold for the spatial arrangement of twelve functional groups with high geometric precision. This unique molecular symmetry identifies such polyfunctional organic building blocks as potential highly connective linkers for coordination polymer and metal-organic framework synthesis. Hereby, the linker exhibits a higher connectivity than the metal ions and with the main connectivity based on the ligand, this can create a new type of inversely cross-linked framework. Two hexakis adducts bearing either twelve glycolic acid or 3-hydroxypropionic acid side chains attached to its malonate units were incorporated as organic connectivity centers in the first fullerene-containing three-dimensional frameworks by coordination with Zn(2+) . PMID:26960246

  19. 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).

  20. 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.

  1. 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

  2. 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.

  3. 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)

  4. 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.

  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. 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.

  7. 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...

  8. 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.

  9. 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...

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Thermal effects of impact bombardments on Noachian Mars

    NASA Astrophysics Data System (ADS)

    Abramov, Oleg; Mojzsis, Stephen J.

    2016-05-01

    Noachian (prior to ca. 3700 Ma) terranes are the oldest and most heavily cratered landscapes on Mars, with crater densities comparable to the ancient highlands of the Moon and Mercury. Intense early cratering affected Mars by melting and fracturing its crust, draping large areas in impact ejecta, generating regional-scale hydrothermal systems, and increasing atmospheric pressure (and thereby, temperature) to periodically re-start an otherwise moribund hydrological cycle. Post primary-accretionary bombardment scenarios that shaped early Mars can be imagined in two ways: either as a simple exponential decay with an approximately 100 Myr half-life, or as a "sawtooth" timeline characterized by both faster-than-exponential decay from primary accretion and relatively lower total delivered mass. Indications are that a late bombardment spike was superposed on an otherwise broadly monotonic decline subsequent to primary accretion, of which two types are investigated: a classical "Late Heavy Bombardment" (LHB) peak of impactors centered at ca. 3900 Ma that lasted 100 Myr, and a protracted bombardment typified by a sudden increase in impactor flux at ca. 4100-4200 Ma with a correspondingly longer decay time (≤400 Myr). Numerical models for each of the four bombardment scenarios cited above show that the martian crust mostly escaped exogenic melting from bombardment. We find that depending on the chosen scenario, other physical effects of impacts were more important than melt generation. Model output shows that between 10 and 100% of the Noachian surface was covered by impact craters and blanketed in resultant (hot) ejecta. If early Mars was generally arid and cold, impact-induced heating punctuated this surface state by intermittently destabilizing the near-subsurface cryosphere to generate regional-scale hydrothermal systems. Rather than being deleterious to the proclivity of Noachian Mars to host an emergent biosphere, this intense early impact environment instead enhanced the volume and duration of its surface/subsurface geophysical habitable zone.

  15. FORMATION OF FULLERENES IN H-CONTAINING PLANETARY NEBULAE

    SciTech Connect

    GarcIa-Hernandez, D. A.; Manchado, A.; Stanghellini, L.; Shaw, R. A.; Villaver, E.; Szczerba, R.; Perea-Calderon, J. V. E-mail: amt@iac.e E-mail: shaw@noao.ed E-mail: eva.villaver@uam.e E-mail: Jose.Perea@sciops.esa.in

    2010-11-20

    Hydrogen depleted environments are considered an essential requirement for the formation of fullerenes. The recent detection of C{sub 60} and C{sub 70} fullerenes in what was interpreted as the hydrogen-poor inner region of a post-final helium shell flash planetary nebula (PN) seemed to confirm this picture. Here, we present strong evidence that challenges the current paradigm regarding fullerene formation, showing that it can take place in circumstellar environments containing hydrogen. We report the simultaneous detection of polycyclic aromatic hydrocarbons (PAHs) and fullerenes toward C-rich and H-containing PNe belonging to environments with very different chemical histories such as our own Galaxy and the Small Magellanic Cloud. We suggest that PAHs and fullerenes may be formed by the photochemical processing of hydrogenated amorphous carbon. These observations suggest that modifications may be needed to our current understanding of the chemistry of large organic molecules as well as the chemical processing in space.

  16. Analytical description of the sputtering yields of silicon bombarded with normally incident ions

    NASA Astrophysics Data System (ADS)

    Wittmaack, Klaus

    2003-12-01

    Experimentally determined sputtering yields of silicon bombarded with normally incident ions were analyzed with the aim of deriving a complete analytical description of the data. The yields, covering a wide range of energies (from 50 eV to 540 keV) and primary ions of vastly different mass (from H to Xe), can be described in universal form using (i) two energy-dependent functions, the reduced nuclear stopping cross section sn and Bohdansky’s threshold function η, (ii) a modified form of Sigmund’s α function, only dependent on the mass ratio of projectile and target atoms, and (iii) a constant calibration factor x0N/Es, where x0 is the effective mean escape depth of sputtered atoms, N the number density of Si atoms, and Es an effective surface binding energy. Considering the fact that according to computer simulations the mean escape depth increases significantly with increasing projectile energy, the observed constancy of x0N/Es requires the assumption that Es is not a constant but contains two terms, the “true” surface binding energy Es and an additional energy-dependent term presumably reflecting the fraction of deposited energy that is lost in inelastic processes as well as in creating phonons and damage. There are indications that the sputtering yields reported for H and D bombardment as well as for heavy-ion impact at very low energies are too small by factors up to about 2, presumably due to oxygen incorporation and/or growth of surface contamination layers under nonideal vacuum conditions.

  17. 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.

  18. 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

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

    PubMed

    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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. A New Dynamical Model for the Lunar Late Heavy Bombardment

    NASA Technical Reports Server (NTRS)

    Chambers, J. E.; Lissauer, J. J.

    2002-01-01

    We describe a new dynamical model for the late heavy bombardment in which a 5th terrestrial planet existed on an orbit that became unstable after 600 Myr, began crossing the asteroid belt, and enhanced the flux of impactors into the inner Solar System. Additional information is contained in the original extended abstract.

  6. Evidence Supporting an Early as Well as Late Heavy Bombardment of the Moon

    NASA Astrophysics Data System (ADS)

    Frey, H. V.

    2015-02-01

    Evidence supporting an intense early bombardment on the Moon in addition to the traditional Late Heavy Bombardment includes decreasing contrasts in basin topographic relief and Bouguer gravity with increasing crater retention age.

  7. The Jovian Early Bombardment and the Primordial Evolution of Vesta and the Asteroid Belt

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    The formation and migration of Jupiter in the Solar Nebula triggered a short but violent phase of primordial bombardment. Here we show the implications of this Jovian Early Bombardment for the collisional evolution of the asteroid belt and of Vesta.

  8. 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 Green’s 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.

  9. Intramolecular energy transfer in fullerene pyrazine dyads

    SciTech Connect

    Guldi, D.M.; Torres-Garcia, G.; Mattay, J.

    1998-11-26

    Excited-state properties of three different pyrazine derivatives 4--6 were probed by emission and transient absorption spectroscopy. They display emission maxima at 464 (4), 417 (5), and 515 nm (6) that are red-shifted with respect to their strong UV ground-state absorption and formed with overall quantum yields ({Phi}) of 0.156, 0.22, and 0.13, respectively. Once photoexcited, these triplet excited pyrazines undergo rapid intermolecular energy transfer to a monofunctionalized fullerene derivative (7) with bimolecular rate constants ranging from 3.64 {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1} (6) to 1.1 {times} 10{sup 10} M{sup {minus}1} s{sup {minus}1} (4). The product of these bimolecular energy-transfer reactions is in all cases the fullerene triplet excited state. Functionalization of pristine C{sub 60} with the investigated pyrazine derivatives promotes the UV-vis absorption characteristics and, in turn, improves the light-harvesting efficiency of the resulting dyads 1--3 relative to pristine C{sub 60}. Photoexcitation of the pyrazine moieties in dyads 1--3 leads to the formation of their singlet excited states. In contrast to the pyrazine models, photoexcitation of dyad 1--3 is followed by rapid intramolecular deactivation processes of the latter via energy transfer to the fullerene ground state with half-lives between 37 and 100 ps. In turn, energy transfer transforms the short-lived and moderately redox-active singlet excited states of pyrazine into the highly reactive fullerene triplet excited state. The latter is found to produce effectively singlet oxygen ({sup 1}O{sub 2}) with quenching rate constants for 1--3 of (1--1.5) {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1}. Similarly, reductive quenching of the triplet excited states in dyads 1--3 via electron transfer with diazabicyclooctane (DABCO) occurs with rate constants of 5.2--9.4 {times} 10{sup 7} M{sup {minus}1} s{sup {minus}1}.

  10. Engineering the physical parameters for continuous synthesis of fullerene peapods

    NASA Astrophysics Data System (ADS)

    Tiwari, Neeru; Pandey, Nayancee; Roy, Debmalya; Mukhopadhyay, K.; Eswara Prasad, N.

    2016-05-01

    Previous efforts to insert fullerenes into a carbon nanotube (CNT) involved the isolated synthesis of CNTs and fullerenes and then annealing CNTs and fullerenes together for encapsulation. We demonstrated the process for the continuous production of fullerene peapods inside the arc instrument by modifying the conventional arc ablation system, which can be repeated to obtain the desired mass scale product. Inside the arc discharge unit, by using the tunable external magnetic field, the double-walled CNTs (DWCNTs) were first synthesized and then directed to deposit onto the water cooled aluminium (Al) plate. The openings were created on DWCNTs by controlled heating of the Al plate and then fullerenes were synthesized and deposited on DWCNTs. In the arc instrument, fullerenes were finally directed to enter into DWCNTs from the defect sites by heating the Al plate in a vacuum. The formation of the peapod was established by the structure-property studies despite the huge deposition of metal catalyst nanoparticles and fullerenes on the surface of the nanotube which were a serious challenge for molecular level characterization of the grown peapod structures.

  11. 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

  12. 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

  13. Engineering the physical parameters for continuous synthesis of fullerene peapods.

    PubMed

    Tiwari, Neeru; Pandey, Nayancee; Roy, Debmalya; Mukhopadhyay, K; Eswara Prasad, N

    2016-05-20

    Previous efforts to insert fullerenes into a carbon nanotube (CNT) involved the isolated synthesis of CNTs and fullerenes and then annealing CNTs and fullerenes together for encapsulation. We demonstrated the process for the continuous production of fullerene peapods inside the arc instrument by modifying the conventional arc ablation system, which can be repeated to obtain the desired mass scale product. Inside the arc discharge unit, by using the tunable external magnetic field, the double-walled CNTs (DWCNTs) were first synthesized and then directed to deposit onto the water cooled aluminium (Al) plate. The openings were created on DWCNTs by controlled heating of the Al plate and then fullerenes were synthesized and deposited on DWCNTs. In the arc instrument, fullerenes were finally directed to enter into DWCNTs from the defect sites by heating the Al plate in a vacuum. The formation of the peapod was established by the structure-property studies despite the huge deposition of metal catalyst nanoparticles and fullerenes on the surface of the nanotube which were a serious challenge for molecular level characterization of the grown peapod structures. PMID:27070531

  14. 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.

  15. 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.

  16. Enhancement of the 6.4 keV Line in the Inner Galactic Ridge: Proton-induced Fluorescence?

    NASA Astrophysics Data System (ADS)

    Nobukawa, K. K.; Nobukawa, M.; Uchiyama, H.; Tsuru, T. G.; Torii, K.; Tanaka, T.; Chernyshov, D. O.; Fukui, Y.; Dogiel, V. A.; Koyama, K.

    2015-07-01

    A common idea for the origin of the Galactic diffuse X-ray emission, particularly that of the iron lines from neutral and highly ionized atoms, is a superposition of many cataclysmic variables and coronally active binaries. In this scenario, the flux should symmetrically distribute between the east and west on the plane with respect to Sagittarius A* because the stellar mass distribution determined by infrared observations is nearly symmetric. This symmetry is confirmed for the highly ionized iron line as well as the continuum emission. However, a clear excess of the neutral iron line in the near east of the Galactic center compared to the near-west side is found. The flux distribution of the excess emission well correlates with the molecular column density. The X-ray spectrum of the excess emission is described by a power-law continuum plus a 6.4 keV line with a large equivalent width of ˜1.3 keV, which is hardly explained by the low-energy electron bombardment scenario. The longitudinal and latitudinal distribution of the excess emission disfavors the X-ray irradiation, either by Sagittarius A* or by nearby X-ray binaries. Then, the low-energy proton bombardment is the most probable origin, although the high-energy density ˜80 eV cm-3 in 0.1-1000 MeV is required and there is no conventional proton source in the vicinity.

  17. Spectroscopy from 2 to 200 kev

    SciTech Connect

    Helfand, D.J.; Chanan, G.A.

    1981-11-01

    The astrophysical processes responsible for line and continuum emission in the spectra range 2 keV to 200 keV are examined from the viewpoint of designing a spectrometer which would operate in this regime. Phenomena considered include fluorescent line radiation in X-ray binaries, magnetically shifted iron lines and cyclotron emission from neutron star surfaces, line emission from cosmically abundant elements in thermal plasmas, and nuclear deexcitation lines in fresh nucleosynthetically produced matter. An instrument consisting of a approximately 10 sq cm array of planar germanium detectors surrounded by a large sodium-iodide anticoincidence shield is described and projected background rates and sensitivities are considered. A sample observing program for a two-day shuttle-based mission is included as an example of the wide range of scientific questions which could be addressed by such an instrument.

  18. Noncovalent endo-binding of fullerenes to diprotonated bisporphyrins.

    PubMed

    Jung, Sunghan; van Paauwe, John D; Boyd, Peter D W; Shin, Seung Koo

    2011-12-01

    Noncovalent binding of fullerenes to bisporphyrins was studied in the gas phase by energy-dependent collision-induced dissociation (CID) with Xe under single-collision conditions. The electrospray ionization mass spectra of calix[4]arene-linked bisporphyrins show that bisporphyrins take up to 3-4 protons, depending on the type of meso-substituents. Of the protonated bisporphyrins, the diprotonated species form stable 1:1 complexes with fullerenes (C(60) and C(70)). CID cracking patterns of the diprotonated bisporphyrins indicate that each monomeric porphyrin moiety is singly protonated. CID yield-energy curves obtained from the 1:1 diprotonated bisporphyrin-fullerene complexes suggest that a fullerene occupies the endo-binding site intercalated between the two singly protonated porphyrin moieties. In the cases of 1:2 diprotonated bisporphyrin-fullerene complexes, CID results show that one fullerene binds inside (endo-binding) and the other outside (exo-binding). The exo-binding mode is energetically almost identical to the binding of fullerenes to singly protonated porphyrin monomers. The endo-binding energy is at least twice the exo-binding energy. To gain insights into the binding mode, we optimized structures of diprotonated bisporphyrins and their 1:1 endo-complexes with fullerenes, and calculated the endo-binding energy for C(60), C(70) (end-on), and C(70) (side-on). The endo-binding of fullerenes to diprotonated bisporphyrins nearly doubles the π-π interactions while reducing the electrostatic repulsion between the two singly protonated porphyrin moieties. The side-on binding of C(70) is favored over the end-on binding because the former exerts less steric strain to the lower rim of calixarene. PMID:21993661

  19. Synthesis of fullerenic nanocapsules from bio-molecule carbonisation

    NASA Astrophysics Data System (ADS)

    Tsang, Shik Chi; Qiu, Jieshan; Harris, Peter J. F.; Fu, Qi Jia; Zhang, Ning

    2000-06-01

    There has been great interest in the incorporation of foreign materials into fullerene structures (C 60, nanotubes, nanoparticles, onions). This interest has been driven by the potential applications of the filled fullerenes, which lie in areas as diverse as optical, electronic, magnetic recording materials and nuclear medicine. In particular, the onion structures of extreme strength may offer excellent protection to their encapsulated nanomaterials for applications. Here, we describe controlled carbonisation of an iron-containing biomolecule, ferritin, at elevated temperatures. This simple technique produces macroscopic quantities of quasi-spherical fullerenic shells (onions) that encapsulate iron nanoparticles of a very narrow range of particle diameters.

  20. Water-soluble fullerene electrolytes. Electrostatic contribution to thermodynamic functions

    NASA Astrophysics Data System (ADS)

    Škerjanc, Jože

    1999-04-01

    The Poisson-Boltzmann equation has been solved to obtain the electrostatic potential for the spherical cell model of a fullerene molecule at which charged groups are attached. The electrostatic internal and free energies, degree of binding of counterions, osmotic coefficient, and distribution of counterions around the charged fullerene shell are calculated. These properties are presented as functions of the concentration, radii of counterions, and surface charge density of the fullerene macroion. Calculated osmotic coefficients are compared with preliminary experimental data for the sodium salt of fullerenehexamalonic acid, C66(COONa)12.

  1. Fast atom bombardment and high performance tandem mass spectrometry of platinum(II) oligodeoxyribonucleotide fragments

    NASA Astrophysics Data System (ADS)

    Costello, Catherine E.; Comess, Kenneth M.; Plaziak, Adam S.; Bancroft, Daniel P.; Lippard, Stephen J.

    1992-12-01

    The antitumor drug cisplatin [cis-diamminedichloroplatinum(II),cis-DDP] exerts its biological activity by binding to cellular DNA. In order to evaluate the utility of mass spectrometry as a possible new approach to investigate the number and type of Pt-DNA adducts in both mechanistic and clinical studies, a systematic survey of the fast atom bombardment (FAB) and high performance tandem mass spectrometry (MS---MS) spectra of a series of well-defined adducts has been carried out. Included in the set of compounds were adducts between cisplatin or its trans isomer and oligodeoxyribonucleotides containing two to six bases, selected to represent all the known binding modes of cisplatin to DNA, and stable isotope-labeled (15N, 195Pt) complexes. In both positive- and negative-ion FAB mass spectra, all compounds yield ions corresponding to the singly-charged intact cluster, and to fragments that arise by loss of one or two ammine groups. The isotope ratio patterns of the clusters indicate that mixed species containing varying numbers of hydrogens are present. MS--MS spectra obtained after high energy (1-7keV) collisionally-induced dissociation (CID) have more extensive fragmentation. Two sets of product ions indicative of the Pt- binding site are consistently present; these correspond to Pt(NH3)0-2 (Bx or y) and Pt(NH3)0-2 (Bx By), where Bx and By are the nucleobasis linked to Pt in the adduct. CID mass spectra recorded at 1 keV have additional product ions related to the nucleotide sequence.

  2. 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.

  3. Statistical Law of High-Energy Fullerene and Its Derivatives Passing Through Graphene

    NASA Astrophysics Data System (ADS)

    Xu, Zhi-Cheng; Wen, Jia-Le; Zhong, Wei-Rong; Wei, Liang

    2016-03-01

    The behavior of graphene bombarded by fullerene (C60 and C70) and its derivatives through using non-equilibrium molecular dynamics method are studied. The microscopic mechanism of passing through graphene is obviously related to the initial structure of destroying carbon-carbon bonds and the strong interaction between the circular region of graphene and the cluster. The probability of passing through graphene depends on the incident velocity of clusters, the species of clusters, the temperature of heat baths, and the defect of graphene. Our results can provide a perspective for further understanding the mechanism of generating nanopores in graphene. The clusters used here may also bring about some potential utilities in the functionalization of graphene and the production of nanopores. Supported in part by the National Natural Science Foundation of China under Grant Nos. 11004082, and 11291240477, the Natural Science Foundation of Guangdong Province under Grant No. 2014A030313367, and the Fundamental Research Funds for the Central Universities, Jinan University under Grant Nos. 21611437 and 11614341

  4. Temperature-dependent mechanisms of lithium erosion from lithium-based liquid metals under low-energy bombardment

    NASA Astrophysics Data System (ADS)

    Allain, J. P.; Coventry, M. D.; Ruzic, D. N.

    2002-11-01

    Erosion from liquids under low-energy, light-particle bombardment has been studied at the Ion-surface Interaction Experiment (IIAX) facility at the University of Illinois^1. A variety of liquids are studied including lithium, tin-lithium and tin. Quartz crystal microbalance technology is used to measure lithium erosion including evaporation and sputtering under a variety of surface conditions, temperatures and incident particle energies. In addition to these measurements, this work includes self-consistent modeling done with VFTRIM-3D ^2 and TRVMC-95. Results indicate that the near-surface deposited energy density and temperature-dependent surface binding energy are important mechanisms in understanding the erosion behavior of liquid metals as the sample temperature and incident particle energy is varied. The study includes measurements with H^+, D^+, He^+, Ne^+, Ar^+ and Li^+ bombardment at energies between 0.1-1.0 keV and 45-degree incidence. ^1J.P. Allain, D.N. Ruzic, M.R. Hendricks, J. Nucl. Mater. 290-293 (2001) 180. ^2D.N. Ruzic, Nuclear Instrum. Methods B 47 (1990) 118.

  5. 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

  6. 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.

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

    PubMed Central

    Schroeder, Bob C; Li, Zhe; Brady, Michael A; Faria, Gregório Couto; Ashraf, Raja Shahid; Takacs, Christopher J; Cowart, John S; Duong, Duc T; Chiu, Kar Ho; Tan, Ching-Hong; Cabral, João 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

  8. The possible role of anisotropy in kinetic electronic excitation of solids by particle bombardment

    NASA Astrophysics Data System (ADS)

    Heuser, C.; Marpe, M.; Diesing, D.; Wucher, A.

    2011-06-01

    The kinetic excitation of a solid surface by impact of energetic particles is investigated by means of internal electron emission across a buried metal-insulator-metal (MIM) tunnel junction. By bombarding the top metal surface of such a device with keV noble gas ions, internal emission yields were determined as a function of projectile impact energy and angle of incidence with respect to the surface normal. In order to understand the observed impact angle dependence, we apply a modified formalism originally published to describe external electron emission. As a result, we find that the measured data can be explained by assuming the spatial distribution of excited electrons propagating towards the buried oxide interface to be strongly influenced by the projectile impact angle. A simple ballistic model assuming excited electrons generated by direct collisions with the projectile to preferably propagate along the direction of the original projectile motion, while electrons excited by scattering from moving recoils propagate isotropically, appears to describe the observed experimental data quite well.

  9. 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.

  10. 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 ...

  11. Fullerene-Encapsulated Atoms in the Light of Synchrotron Radiation

    SciTech Connect

    Mueller, A.; Schippers, S.; Esteves, D.; Habibi, M.; Phaneuf, R. A.; Kilcoyne, A. L. D.; Aguilar, A.; Dunsch, L.

    2009-12-03

    Mass-selected beams of endohedral fullerene Ce-C{sub 82}{sup +} ions, of atomic Ce{sup q+} ions (q = 2, 3, 4), and of empty fullerene-cage C{sub 82}{sup +} ions were employed to study photoionization of fullerene-encapsulated and free cerium atoms. The Ce 4d inner-shell contributions to single and double ionization of the endohedral Ce-C{sub 82}{sup +} fullerene have been extracted from the data and compared with expectations based on theory and the experiments with atomic Ce ions. Dramatic reduction and redistribution of the ionization contributions to Ce 4d photoabsorption is observed. More than half of the Ce 4d oscillator strength is apparently diverted to additional decay channels of the Ce-C{sub 82}{sup +} complex.

  12. Electron-deficient fullerenes in triple-channel photosystems.

    PubMed

    López-Andarias, Javier; Bolag, Altan; Nançoz, Christoph; Vauthey, Eric; Atienza, Carmen; Sakai, Naomi; Martín, Nazario; Matile, Stefan

    2015-05-01

    Fullerenes of increasing electron deficiency are designed, synthesized and evaluated in multicomponent surface architectures to ultimately build gradients in LUMO levels with nine components over 350 meV down to -4.22 eV. PMID:25846676

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. Defect formation in graphene during low-energy ion bombardment

    NASA Astrophysics Data System (ADS)

    Ahlberg, P.; Johansson, F. O. L.; Zhang, Z.-B.; Jansson, U.; Zhang, S.-L.; Lindblad, A.; Nyberg, T.

    2016-04-01

    This letter reports on a systematic investigation of sputter induced damage in graphene caused by low energy Ar+ ion bombardment. The integral numbers of ions per area (dose) as well as their energies are varied in the range of a few eV's up to 200 eV. The defects in the graphene are correlated to the dose/energy and different mechanisms for the defect formation are presented. The energetic bombardment associated with the conventional sputter deposition process is typically in the investigated energy range. However, during sputter deposition on graphene, the energetic particle bombardment potentially disrupts the crystallinity and consequently deteriorates its properties. One purpose with the present study is therefore to demonstrate the limits and possibilities with sputter deposition of thin films on graphene and to identify energy levels necessary to obtain defect free graphene during the sputter deposition process. Another purpose is to disclose the fundamental mechanisms responsible for defect formation in graphene for the studied energy range.

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

    SciTech Connect

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

    1997-06-20

    Radioactive fullerenes labeled with {sup 11}C 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 {sup 11}C nuclide exists in fullerene cages to extend of about 60-70% of the total amount of {sup 11}C produced when the C{sub 60} sample was irradiated. Also, radioactive endohedral {sup 7}Be-C{sub 60}, {sup 7}Be-C{sub 70} can be detected using radiochemical techniques in the final solvent. Such a {sup 7}Be atom can penetrate into the fullerene cage to produce {sup 7}Be-C{sub 60}, {sup 7}Be-C{sub 70} 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.

  19. 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

  20. Fullerenes and Interplanetary Dust at the Permian-Triassic Boundary

    NASA Astrophysics Data System (ADS)

    Poreda, Robert J.; Becker, Luann

    2003-01-01

    We recently presented new evidence that an impact occurred ~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 3He-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 3He vs. giant impact for fullerene).

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

    PubMed

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

    2011-12-01

    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

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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

  7. Chemistry of fullerene epoxides: synthesis, structure, and nucleophilic substitution-addition reactivity.

    PubMed

    Tajima, Yusuke; Takeshi, Kazumasa; Shigemitsu, Yasuo; Numata, Youhei

    2012-01-01

    Fullerene epoxides, C₆₀O(n), having epoxide groups directly attached to the fullerene cage, constitute an interesting class of fullerene derivatives. In particular, the chemical transformations of fullerene epoxides are expected to play an important role in the development of functionalized fullerenes. This is because such transformations can readily afford a variety of mono- or polyfunctionalized fullerene derivatives while conserving the epoxy ring arrangement on the fullerene surface, as seen in representative regioisomeric fullerene polyepoxides. The first part of this review addresses the synthesis and structural characterization of fullerene epoxides. The formation of fullerene epoxides through different oxidation reactions is then explored. Adequate characterization of the isolated fullerene epoxides was achieved by concerted use of NMR and LC-MS techniques. The second part of this review addresses the substitution of fullerene epoxides in the presence of a Lewis acid catalyst. Most major substitution products have been isolated as pure compounds and their structures established through spectroscopic methods. The correlation between the structure of the substitution product and the oxygenation pattern of the starting materials allows elucidation of the mechanistic features of this transformation. This approach promises to lead to rigorous regioselective production of various fullerene derivatives for a wide range of applications. PMID:22634847

  8. 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

  9. 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.

  10. Fullerene nano ball bearings: an atomistic study

    NASA Astrophysics Data System (ADS)

    Kang, Jeong Won; Hwang, Ho Jung

    2004-05-01

    We investigated fullerene and metallofullerene nano ball bearings using classical molecular dynamics and steepest descent methods based on both the Tersoff-Brenner and the Lennard-Jones 12-6 potentials. Under hydrostatic pressures, the bulk modulus and the ultimate pressure of K @C60 were higher than those of C60. While C60 rolling dynamics were the same as K @C60 rolling dynamics, the sustaining pressure of K @C60 intercalated between layers was higher than that of C60 intercalated between layers. In molecular dynamics simulations of C60 and K @C60 rolling motions, periodic variations of the frictional forces were found and the mean dynamical frictional forces were almost zero. We were able to conclude that K @C60 was more effective than C60 for the application of nano ball bearings.

  11. 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.

  12. 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

  13. Energetics and structures of fullerene crop circles

    NASA Astrophysics Data System (ADS)

    Han, Jie

    1998-01-01

    The energetics and structures of carbon tori are studied using molecular simulation. They include circular and polygonal tori, formed by bending ( n, n) tubes and by joining ( n, n) and ( n+1, n-1) or ( n+2, n-2) tubes with pentagon-heptagon defects, respectively, in which n=5, 8 and 10. The strain energy of a circular and polygonal torus decreases by D-2 and D-1, respectively, where D is the torus diameter. Comparisons in average and local maximum strain suggest that defect-free circular tori are more energetically stable and kinetically accessible than defective polygonal tori. This confirms the hypothesis that circular tori are the predominant constituents of the observed fullerene crop circles in laser-grown single-wall carbon nanotubes.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. A novel BF2-chelated azadipyrromethene-fullerene dyad: synthesis, electrochemistry and photodynamics.

    PubMed

    Amin, Anu N; El-Khouly, Mohamed E; Subbaiyan, Navaneetha K; Zandler, Melvin E; Fukuzumi, Shunichi; D'Souza, Francis

    2012-01-01

    The synthesis, structure, electrochemistry and photodynamics of a BF(2)-chelated azadipyrromethene-fullerene dyad are reported in comparison with BF(2)-chelated azadipyrromethene without fullerene. The attachment of fullerene resulted in efficient generation of the triplet excited state of the azadipyrromethene via photoinduced electron transfer. PMID:22083226

  20. 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.

  1. Molecular dynamics studies of the C(60) fullerene associations in aqueous solutions and a biological membrane

    NASA Astrophysics Data System (ADS)

    Li, Liwei

    The associative behavior of C60 fullerenes in water and a biological membrane was studied using computer molecular dynamics (MD) simulations. Multiple histogram method combined with umbrella sampling technique was used in calculating the fullerene pairwise free energy as a function of separation. It was observed that water wets the fullerene surface due to the high fullerene atomic density and therefore the strong fullerene-water dispersion interaction. Despite the fact of the insolubility of fullerenes, water was found to promote the dispersion of fullerenes in aqueous solution. A decomposition of the solvent-induced potential of mean force between fullerenes into entropy and energy (enthalpy) contributions revealed that the water-induced repulsion between fullerenes is energetic in origin, contrasting strongly to entropy-driven association observed for conventional non-polar solutes. The repulsive interaction was observed to decrease at elevated temperature due to an increasing contribution from a relatively weak entropy-driven association. The surface curvature effect was surveyed by studying nanoparticles of different shapes (fullerene, carbon nanotubes and graphenes) with similar chemical structures. As for a potential application of fullerene in biomedical systems, the poly(ethylene oxide) (PEO) modified fullerene derivative interactions in aqueous solution and the bare fullerene-fullerene interactions inside a dimyristoylphosphatidylcholine (DMPC) lipid bilayer were investigated. It shows that while the attraction between two PEO-modified fullerenes is stronger and longer range than that between two bare C60 fullerenes in aqueous solution, the PEO-modified fullerenes do not phase-separate in water but rather aggregate in chainlike clusters at concentrations where unmodified fullerenes completely phase-separate. The results of pairwise fullerene interactions inside a DMPC lipid shows that fullerenes, constrained in the same lateral plane, was found to be significantly less attractive inside the lipid bilayer than in an alkane melt of the same molecular weight as the surfactant tails. Contrasting to small hydrophobic solutes, fullerene situates off the bilayer center in favor of the stronger dispersion interactions with the denser region of the bilayer.

  2. 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.

  3. The Jovian Early Bombardment and the collisional erosion of primordial asteroids

    NASA Astrophysics Data System (ADS)

    Turrini, D.; Magni, G.

    2012-09-01

    The formation of Jupiter triggered the Jovian Early Bombardment, the first bombardment event in the history of the Solar System. The Jovian Early Bombardment was caused by the appearance of the orbital resonances with Jupiter both in the inner and the outer Solar System. The Jovian Early Bombardment is relatively short, the bulk of the bombardment taking place in about 1 Ma, but it is extremely violent due to the higher population of planetesimals existing at the time in the regions affected by the resonances. In all scenarios we considered, primordial asteroids whose size did not exceed 200 km were collisionally eroded during the Jovian Early Bombardment. Moreover, a radial migration of the order 0.5 AU or greater of the planet while forming would have caused also primordial asteroids the size of Vesta to be stripped of a significant fraction of their mass.

  4. Analysis of glycolipids by fast atom bombardment mass spectrometry.

    PubMed

    Bosch, M P; Parra, J L; Manresa, M A; Ventura, F; Rivera, J

    1989-12-01

    The positive and negative ion fast atom bombardment (FAB) mass spectra of four glycolipids obtained from microbial cultures are reported. The spectra of the glycolipids in the positive ion mode are characterized by abundant [M + Na]+, [M + Na + matrix]+ and [M + 2Na - H]+ species. In negative FAB conditions the molecules yield [M - H]-. Our understanding of the FAB behaviour of glycolipids in both positive and negative modes has been considerably aided in the structure elucidation, without any derivatization or degradation reaction of the compounds studied. The technique allows unambiguous molecular weight determination of low-microgram amounts of these glycolipids purified from biological sources and provides useful fragmentation information. PMID:2611417

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. [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.

  12. 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

  13. Fullerene data mining using bibliometrics and database tomography

    PubMed

    Kostoff; Braun; Schubert; Toothman; Humenik

    2000-01-01

    Database tomography (DT) is a textual database analysis system consisting of two major components: (1) algorithms for extracting multiword phrase frequencies and phrase proximities (physical closeness of the multiword technical phrases) from any type of large textual database, to augment (2) interpretative capabilities of the expert human analyst. DT was used to derive technical intelligence from a fullerenes database derived from the Science Citation Index and the Engineering Compendex. Phrase frequency analysis by the technical domain experts provided the pervasive technical themes of the fullerenes database, and phrase proximity analysis provided the relationships among the pervasive technical themes. Bibliometric analysis of the fullerenes literature supplemented the DT results with author/journal/institution publication and citation data. Comparisons of fullerenes results with past analyses of similarly structured near-earth space, chemistry, hypersonic/supersonic flow, aircraft, and ship hydrodynamics databases are made. One important finding is that many of the normalized bibliometric distribution functions are extremely consistent across these diverse technical domains and could reasonably be expected to apply to broader chemical topics than fullerenes that span multiple structural classes. Finally, lessons learned about integrating the technical domain experts with the data mining tools are presented. PMID:10661546

  14. 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.

  15. The first stable lower fullerene: C{sub 36}

    SciTech Connect

    Piskoti, C.; Zettl, A.

    1998-08-01

    A new pure carbon material, presumably composed of thirty six carbon atom molecules, has been synthesized and isolated in milligram quantities. It appears as though these molecules have a closed cage structure making them the smallest member of a new class of molecules known as fullerenes, most notably of which is the soccer ball shaped C{sub 60}. However, unlike other known fullerenes, any closed, fullerene-like C{sub 36} cage will necessarily contain fused pentagon rings. Therefore, this molecule apparently violates the isolated pentagon rule, a criterion which requires isolated pentagons for stability in fullerene molecules. Striking parallels between this problem and the synthesis of other fused five member fused ring systems will be discussed. Also, it will be shown that certain biological structures known as clathrin behave in a manner which gives excellent predictions about fullerenes and nanotubes. These predictions help to explain the presence of abundant quantities of C{sub 36} in arced graphite soot. {copyright} {ital 1998 American Institute of Physics.}

  16. 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.

  17. 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%.

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

    PubMed

    Asaji, T; Ohba, T; Uchida, T; Minezaki, H; Ishihara, S; Racz, R; Muramatsu, M; Biri, S; Kitagawa, A; Kato, Y; Yoshida, Y

    2014-02-01

    A synthesis technology of endohedral fullerenes such as Fe@C60 has developed with an electron cyclotron resonance (ECR) ion source. The production of N@C60 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. PMID:24593515

  19. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    A synthesis technology of endohedral fullerenes such as Fe@C60 has developed with an electron cyclotron resonance (ECR) ion source. The production of N@C60 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.

  1. 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.

  2. 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.

  3. Singlet-oxygen generator on base of solid-state fullerene-containing structures for fullerene-oxygen-iodine laser design: physical principles

    NASA Astrophysics Data System (ADS)

    Belousova, Inna M.; Belousov, V. P.; Danilov, Oleg B.; Ermakov, A. V.; Kiselev, V. M.; Krys'ko, A. V.; Murav'eva, T. D.; Ponomarev, A. N.; Sosnov, Eugene N.

    2005-03-01

    The singlet oxygen generator development is the basic problem of fullerene oxygen iodine laser design. Physival principles of singlet oxygen generator on the base of solid-state fullerene-containing structures were investigated. The solid-state singlet oxygen generator is a surface of membranous structures with embedded fullerenes (fullerites) of fullerene-like nanostructures - astralenes. Singlet oxygen is generated by interaction of molecular oxygen, sorbed by the surface and fullerene-like nanostructures, photoexcited by optical pump. The singlet oxygen entrance in gas phase occurs as a desorption wave, caused by surface heating by optical pump. The effectiveness of molecular oxygen sorption by fullerene C60 and astralen depending on temperature, the extent of nanostructures heating, oxygen pressure and morphology of coating was studies.

  4. 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.

  5. Bonding of endohedral atoms in small carbon fullerenes

    SciTech Connect

    Jackson, K. ); Kaxiras, E. ); Pederson, M.R. )

    1994-08-11

    We present a simple model for understanding the bonding of endohedral atoms in small fullerene cages, based on their approximate spherical shape. Previous work has shown that the one-electron wave functions of a fullerene cage can be assigned angular momentum quantum numbers which describe their overall angular character. These quantum numbers form the basis for approximate selection rules which govern the bonding with endohedral atoms. With this model we successfully address the very different bonding of various tetravalent elements in C[sub 28] and the remarkably strong bonding of U in this small fullerene. We also make several specific predictions regarding the stability of other endohedral complexes. 24 refs., 4 figs., 2 tabs.

  6. Formation of Langmuir-Blodgett films of a fullerene

    SciTech Connect

    Nakamura, Takayoshi; Tachibana, Hiroaki; Yumura, Motoo; Matsumoto, Mutsuyoshi; Azumi, Reiko; Tanaka, Motoo; Kawabata, Yasujiro )

    1992-01-01

    The Langmuir-Blodgett (LB) films of the fullerene (C[sub 60]) were formed with and without matrix molecules. The pure C[sub 60] formed a collapsed film at the air-water interface. The surface of the transferred film was inhomogeneous, as observed by atomic force microscopy (AFM). The monolayers of a 1:1 mixture with icosanoic acid were transferred onto substrates with good quality. The LB films had a smooth surface composed of a mixture of C[sub 60] and icosanoic acid dispersed with flat microcrystals of C[sub 60] observed by AFM. The 1:1 mixture with dioctadecyldimethylammonium perchlorate was deposited as Z-type film onto the substrates. The absorption spectra of both of the mixed films were in good agreement with those of evaporated films. These films will be precursors of the molecular systems utilizing the peculiar properties of fullerenes and fullerene anions. 13 refs., 4 figs.

  7. Chemical modification of fluorinated self-assembled monolayer surfaces by low energy reactive ion bombardment.

    PubMed

    Pradeep, T; Feng, B; Ast, T; Patrick, J S; Cooks, R G; Pachuta, S J

    1995-03-01

    Reactive collisions of low energy (<100-eV) mass-selected ions are used to chemically modify fluorinated self-assembled monolayer surfaces comprised of alkanethiolate chains CF3(CF2)11(CH2)2S- bound to Au. Typical experiments were done by using 1-nA/cm(2) beams and submonolayer doses of reactant ions. Characterization of the modified surface was achieved by in situ chemical sputtering (60-eV Xe(+·)) and by independent high mass resolution time-of-flight-secondary ionization mass spectrometry (TOF-SIMS) (15-25-keV, Ga(+)) experiments. Treatment with Si(35)C1 4 (+·) produced a surface from which Xe(+) sputtering liberated CF2 (35)C1(+) ions, which suggested Cl-for-F halogen exchange at the surface. Isotopic labeling studies that used Si(35)Cl2 (37)Cl 2 (+·) ; and experiments with bromine-containing and iodine-containing projectiles, confirmed this reaction. High mass resolution TOF-SIMS spectra, as well as high spatial resolution images, provided further evidence as to the existence of halogen-exchanged species at the bombarded surface. Analogous Cl-for-F halogen substitution was observed in a model gas-phase reaction. The ion-surface reaction is suggested to proceed through an intermediate fluoronium ion in which the projectile is bonded to the target molecule. The most significant conclusion of the study is that selective chemical modification of monolayer surfaces can be achieved by using reactive ion beams, which lead to new covalent bonds at the surface and in the scattered ions. PMID:24214116

  8. Endohedral Fullerenes for Organic Photovoltaic Devices

    SciTech Connect

    Ross, R. B.; Cardona, C. M.; Guldi, D. M.; Sankaranarayanan, S. G.; Reese, M. O.; Kopidakis, N.; Peete, J.; Walker, B.; ZBazan, G. C.; Van Keuren, E.; Holloway,; B. C.; Drees, M.

    2009-03-01

    So far, one of the fundamental limitations of organic photovoltaic (OPV) device power conversion efficiencies (PCEs) has been the low voltage output caused by a molecular orbital mismatch between the donor polymer and acceptor molecules. Here, we present a means of addressing the low voltage output by introducing novel trimetallic nitride endohedral fullerenes (TNEFs) as acceptor materials for use in photovoltaic devices. TNEFs were discovered in 1999 by Stevenson et al.; for the first time derivatives of the TNEF acceptor, Lu{sub 3}N{at}C{sub 80}, are synthesized and integrated into OPV devices. The reduced energy offset of the molecular orbitals of Lu{sub 3}N{at}C{sub 80} to the donor, poly(3-hexyl)thiophene (P3HT), reduces energy losses in the charge transfer process and increases the open circuit voltage (V{sub oc}) to 260 mV above reference devices made with [6,6]-phenyl-C{sub 61}-butyric methyl ester (C{sub 60}-PCBM) acceptor. PCEs >4% have been observed using P3HT as the donor material. This work clears a path towards higher PCEs in OPV devices by demonstrating that high-yield charge separation can occur with OPV systems that have a reduced donor/acceptor lowest unoccupied molecular orbital energy offset.

  9. Spin-on carbon using fullerene derivatives

    NASA Astrophysics Data System (ADS)

    Frommhold, A.; Brown, A. G.; Lada, T.; Palmer, R. E.; Robinson, A. P. G.

    2014-03-01

    Progress in lithographic resolution has made the adoption of extremely thin photoresist films necessary for the fabrication of `2× nm' structures to prevent issues such as resist collapse during development. While there are resists with high etch durability, ultimately etch depth is limited by resist thickness. A possible solution is the use of a multilayer etch stack. For organic hardmasks a carbon-rich material is preferred as carbon possesses a high etch resistance in silicon etch plasma processes. In terms of manufacturability it is beneficial to spin coat the carbon layer instead of using chemical vapor deposition, but the presence of carbon-hydrogen bonds in typical spin on carbon leads to line wiggling during the etch. We have previously introduced a fullerene based `spin on carbon' (SoC) with high etch durability and reported on material characterization. Here we show recent advances in material development and work towards commercialization. The low hydrogen level in the material allows for high resolution etching without wiggling.

  10. Endohedral fullerenes for organic photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Ross, Russel B.; Cardona, Claudia M.; Guldi, Dirk M.; Sankaranarayanan, Shankara Gayathri; Reese, Matthew O.; Kopidakis, Nikos; Peet, Jeff; Walker, Bright; Bazan, Guillermo C.; van Keuren, Edward; Holloway, Brian C.; Drees, Martin

    2009-03-01

    So far, one of the fundamental limitations of organic photovoltaic (OPV) device power conversion efficiencies (PCEs) has been the low voltage output caused by a molecular orbital mismatch between the donor polymer and acceptor molecules. Here, we present a means of addressing the low voltage output by introducing novel trimetallic nitride endohedral fullerenes (TNEFs) as acceptor materials for use in photovoltaic devices. TNEFs were discovered in 1999 by Stevenson et al. ; for the first time derivatives of the TNEF acceptor, Lu3N@C80, are synthesized and integrated into OPV devices. The reduced energy offset of the molecular orbitals of Lu3N@C80 to the donor, poly(3-hexyl)thiophene (P3HT), reduces energy losses in the charge transfer process and increases the open circuit voltage (Voc) to 260mV above reference devices made with [6,6]-phenyl-C61-butyric methyl ester (C60-PCBM) acceptor. PCEs >4% have been observed using P3HT as the donor material. This work clears a path towards higher PCEs in OPV devices by demonstrating that high-yield charge separation can occur with OPV systems that have a reduced donor/acceptor lowest unoccupied molecular orbital energy offset.

  11. 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 σ-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.

  12. 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

  13. Mapping fullerene crystallization in a photovoltaic blend: an electron tomography study.

    PubMed

    Bäcke, Olof; Lindqvist, Camilla; Diaz de Zerio Mendaza, Amaia; Gustafsson, Stefan; Wang, Ergang; Andersson, Mats R; Müller, Christian; Olsson, Eva

    2015-05-14

    The formation of fullerene crystals represents a major degradation pathway of polymer/fullerene bulk-heterojunction thin films that inexorably deteriorates their photovoltaic performance. Currently no tools exist that reveal the origin of fullerene crystal formation vertically through the film. Here, we show that electron tomography can be used to study nucleation and growth of fullerene crystals. A model bulk-heterojunction blend based on a thiophene-quinoxaline copolymer and a fullerene derivative is examined after controlled annealing above the glass transition temperature. We image a number of fullerene nanocrystals, ranging in size from 70 to 400 nanometers, and observe that their center is located close to the free-surface of spin-coated films. The results show that the nucleation of fullerene crystals predominately occurs in the upper part of the films. Moreover, electron tomography reveals that the nucleation is preceded by more pronounced phase separation of the blend components. PMID:25891364

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Stability of uniform electronic wavepackets in chains and fullerenes

    NASA Astrophysics Data System (ADS)

    Chaves Filho, Valdemir L.; Lima, Rodrigo P. A.; de Moura, F. A. B. F.; Lyra, Marcelo L.

    2015-05-01

    In this paper, we investigate the influence of electron-lattice interaction on the stability of uniform electronic wavepackets on chains as well as on several types of fullerenes. We will use an effective nonlinear Schrödinger equation to mimic the electron-phonon coupling in these topologies. By numerically solving the nonlinear dynamic equation for an initially uniform electronic wavepacket, we show that the critical nonlinear coupling above which it becomes unstable continuously decreases with the chain size. On the other hand, the critical nonlinear strength saturates on a finite value in large fullerene buckyballs. We also provide analytical arguments to support these findings based on a modulational instability analysis.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Sputtering yield of Pu bombarded by fission Fragments from Cf

    SciTech Connect

    Danagoulian, Areg; Klein, Andreas; Mcneil, Wendy V; Yuan, Vincent W

    2008-01-01

    We present results on the yield of sputtering of Pu atoms from a Pu foil, bombarded by fission fragments from a {sup 252}Cf source in transmission geometry. We have found the number of Pu atoms/incoming fission fragments ejected to be 63 {+-} 1. In addition, we show measurements of the sputtering yield as a function of distance from the central axis, which can be understood as an angular distribution of the yield. The results are quite surprising in light of the fact that the Pu foil is several times the thickness of the range of fission fragment particles in Pu. This indicates that models like the binary collision model are not sufficient to explain this behavior.

  12. Optical radiation from regions downstream of mercury bombardment thrusters

    NASA Technical Reports Server (NTRS)

    Milder, N. L.; Sovey, J. S.

    1972-01-01

    A 0.5 meter focal length, plane grating monochromator was used to measure the radiance of spectral radiation emanating from regions downstream of a mercury bombardment thruster. The wavelength range investigated was 2800 A. This radiation was due primarily to the radiative decay of excited mercury atoms exhausted from the thruster. Radiance values ranged from 10 to the minus 11th power to 10 to the minus 9th power W/sq cm sr, varying with wavelength. For resonant radiation, the spectral radiance may exceed 10 to the minus 8th power W/sq cm sr. From such radiance measurements, it was concluded that the thruster background radiation should not interfere with the control functions of a star tracker viewing through the thruster exhaust, provided that the tracker is designed to operate with a sufficiently small field of view.

  13. 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.

  14. 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.

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

    PubMed

    Philipp, Patrick; Angerer, Tina B; Sämfors, 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

  16. 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

  17. UV photostability of PMMA-C60 fullerene composition

    NASA Astrophysics Data System (ADS)

    Pozdnyakov, O. F.; Popov, E. O.; Pozdnyakov, A. O.

    2012-12-01

    Thermal decomposition of pure poly(methyl methacrylate) (PMMA) and its composition with C60 fullerene before and after UV irradiation has been studied by thermodesorption mass spectrometry (TDMS). It is established that low-temperature depolymerization of UV-irradiated PMMA is suppressed in its composition with C60. Possible molecular stabilization mechanisms are discussed.

  18. 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.

  19. 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.

  20. Comment on 'Carbon and fullerene nanomaterials in plant system'.

    PubMed

    Dasgupta-Schubert, N; Tiwari, D K; Villaseñor Cendejas, L M

    2016-01-01

    A recent review article entitled "Carbon and fullerene nanomaterials in plant system" published in this journal, misinterprets a component of our (published) work on the interactions of carbon nanotubes with plants. In this comment, we provide the rationale to counter this misconstruction. PMID:27066901

  1. 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

  2. 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 ...

  3. 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).

  4. 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 Euclid’s “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

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

    NASA Astrophysics Data System (ADS)

    Böke, 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 Å-1 and from the relativistic modified atomic form factors for values of x≥1 Å-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.

  6. Manganese(III) acetate-mediated radical reaction of [60]fullerene with phosphonate esters affording unprecedented separable singly-bonded [60]fullerene dimers.

    PubMed

    Wang, Guan-Wu; Wang, Cong-Zhou; Zhu, San-E; Murata, Yasujiro

    2011-06-01

    Radical reaction of [60]fullerene with phosphonate esters mediated by manganese(III) acetate in chlorobenzene afforded singly-bonded fullerene dimers, of which the individual meso and racemic isomers could be unexpectedly separated out for the first time. PMID:21512710

  7. Acceleration of the d+d reaction in metal lithium acoustic cavitation with deuteron bombardment from 30 to 70 keV

    NASA Astrophysics Data System (ADS)

    Toriyabe, Y.; Yoshida, E.; Kasagi, J.; Fukuhara, M.

    2012-05-01

    Fusion reactions 6Li(d,α)4He and 2H(d,p)3H were measured in liquid Li. An ultrasonic target system was developed to form acoustic cavitation bubbles in liquid Li as an additional target. The material uncertainties of the target surface, which have been noted in solid target experiments, were completely rejected because contaminants could be removed in the liquid phase. The Li+d reaction was not affected by the cavitation process, and the derived screening potential was Us=543±38(sta.) -153+83(sys.) eV. This value can be explained by ionic Debye screening if liquid Li is regarded as a low-temperature dense plasma. The d+d reaction was found to be enhanced several times by Li cavitation, whereas the yield of the Li+d reaction remained constant; the ultrasonic effect depends strongly on the target conditions. The enhancement is caused not by Coulomb screening but by the high deuteron temperature in the cavity. The temperature was deduced from the energy dependence of the nuclear reaction enhancement rate as kTd=590±54(sta.) -457+676(sys.) eV. A kinematic analysis also yielded consistent results. Although no meaningful bubble fusion events were observed, extremely large reaction enhancements were occasionally observed.

  8. [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

  9. [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…

  10. Measurements of Neutron Capture Cross Sections for DY Isotopes in the Energy Region from 10 TO 90 KEV

    NASA Astrophysics Data System (ADS)

    Kim, G. N.; Min, Y. G.; Ro, T. I.; Kim, H. D.; Ahn, J. K.; Mizuno, S.; Ohsaki, T.; Igashira, M.

    2003-06-01

    The neutron capture cross sections of Dy isotopes (161Dy, 162Dy, 163Dy, and 164Dy) have been measured in the neutron energy range from 10 to 90 keV using the 3-MV Pelletron accelerator of the Research Laboratory for Nuclear Reactors at the Tokyo Institute of Technology. Pulsed keV neutrons were produced from the 7Li(p, n)7Be reaction by bombarding the lithium target with the 1.5-ns bunched proton beam from the Pelletron accelerator. The incident neutron spectrum on a capture sample was measured by means of a TOF method with a 6Li-glass detector. Capture γ-rays were detected with a large anti-Compton NaI(Tl) spectrometer, employing a TOF method. A pulse-height weighting technique was applied to observed capture γ-ray pulse-height spectra to derive capture yields. The capture cross sections were obtained by using the standard capture cross sections of 197Au. The present results were compared with the previous measurements and the evaluated values of ENDF/B-VI.

  11. Small-angle X-ray scattering study of the structure of powder fullerene C{sub 60} and fullerene soot

    SciTech Connect

    Ginzburg, B. M. Tuichiev, Sh.; Tabarov, S. Kh.; Shepelevskii, A. A.

    2007-03-15

    Powder samples of fullerene C{sub 60} and fullerene soot have been studied by the small-angle X-ray scattering method. The radii of gyration of scattering elements have been determined by constructing small-angle diffraction patterns in Guinier coordinates. The data obtained agree well with the results of wide-angle X-ray scattering study, the available data on the structure of the powder fullerene C{sub 60} prepared by the Huffman-Kraetschmer technique, and the structure of the C{sub 60} molecules. Conglomerates of two C{sub 60} molecules, along with crystallites {approx}20 nm in size that are distributed in an amorphous matrix, are present in fullerene powders. Fullerene soot contains C{sub 60} crystallites 20-25 nm in size and graphite crystallites {approx}2-3 nm in size that are distributed in an amorphous matrix.

  12. A computational atomistic study of the relaxation of ion-bombarded c-Si on experimental time-scales: an application of the kinetic Activation Relaxation Technique

    NASA Astrophysics Data System (ADS)

    Béland, Laurent Karim; Mousseau, Normand

    2012-02-01

    The kinetic activation relaxation technique (kinetic ART) method, an off-lattice, self-learning kinetic Monte Carlo (KMC) algorithm with on-the-fly event search,ootnotetextL. K. B'eland, P. Brommer, F. El-Mellouhi, J.-F. Joly and N. Mousseau, Phys. Rev. E 84, 046704 (2011). is used to study the relaxation of c-Si after Si^- bombardment at 3 keV. We describe the evolution of the damaged areas at room-temperature and above for periods of the order of seconds, treating long-range elastic deformations exactly. We assess the stability of the nanoscale structures formed by the damage cascade and the mechanisms that govern post-implantation annealing.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. Electron-beam-deposited thin polymer films - Electrical properties vs bombarding current.

    NASA Technical Reports Server (NTRS)

    Babcock, L. E.; Christy, R. W.

    1972-01-01

    Polymer films about 150 A thick, deposited on glass substrates by electron bombardment of tetramethyltetraphenyltrisiloxane, were studied, after being sandwiched between evaporated aluminum electrodes, the top one semitransparent. The capacitance, conductance, and photoconductance of the sandwiches were measured at room temperature as a function of the electron bombarding current which formed the polymer. The polymer thickness was obtained independently from Christy's (1960) empirical formula for the rate of formation. The obtained results indicate that, with increasing bombarding current, the polymer undergoes an increase in both crosslinking bonds and dangling bonds. Exposure to air drastically reduces the density of dangling bonds, but does not affect the crosslinking.

  1. 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.

  2. 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.

  3. Controlling Exciton Diffusion and Fullerene Distribution in Photovoltaic Blends by Side Chain Modification.

    PubMed

    Sajjad, Muhammad T; Ward, Alexander J; Kästner, Christian; Ruseckas, Arvydas; Hoppe, Harald; Samuel, Ifor D W

    2015-08-01

    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

  4. 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

  5. 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.

  6. 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

  7. 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 Å/min to 19 Å/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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. Ion peening and stress relaxation induced by low-energy atom bombardment of covalent solids

    SciTech Connect

    Koster, Monika; Urbassek, Herbert M.

    2001-06-01

    Using molecular-dynamics simulation, we study the buildup and relaxation of stress induced by low-energy ({le}150 eV) atom bombardment of a target material. The effect is brought out most clearly by using an initially compressed specimen. As target material, we employ Si, based on the Tersoff potential. By varying the bond strength in the potential, we can specifically study its effect on damage production and stress changes. We find that in general, stress is relaxed by the atom bombardment; only for low bombarding energies and strong bonds, atom bombardment increases stress. We rationalize this behavior by considering the role of energized atoms and of recoil-implanted target atoms.

  16. 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.

  17. 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.

  18. Selecting boron fullerenes by cage-doping mechanisms.

    PubMed

    Boulanger, Paul; Morinière, Maxime; Genovese, Luigi; Pochet, Pascal

    2013-05-14

    So far, no boron fullerenes were synthesized: more compact sp(3)-bonded clusters are energetically preferred. To circumvent this, metallic clusters have been suggested by Pochet et al. [Phys. Rev. B 83, 081403(R) (2011)] as "seeds" for a possible synthesis which would topologically protect the sp(2) sector of the configuration space. In this paper, we identify a basic pentagonal unit which allows a balance between the release of strain and the self-doping rule. We formulate a guiding principle for the stability of boron fullerenes, which takes the form of an isolated filled pentagon rule (IFPR). The role of metallic clusters is then reexamined. It is shown that the interplay of the IFPR and the seed-induced doping breaks polymorphism and its related problems: it can effectively select between different isomers and reduce the reactivity of the boron shells. The balance between self and exterior doping represents the best strategy for boron buckyball synthesis. PMID:23676039

  19. 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

  20. A new fullerene complexation ligand: N-pyridylfulleropyrrolidine.

    PubMed

    Tat, Fatma T; Zhou, Zhiguo; MacMahon, Shaun; Song, Fayi; Rheingold, Arnold L; Echegoyen, Luis; Schuster, David I; Wilson, Stephen R

    2004-07-01

    The subject of this paper is a new fullerene building block design with the potential for defined geometry and good electronic communication. The synthesis and characterization of a new pyridinofullerene ligand capable of forming axially symmetric complexes with metalloporphyrins is reported. X-ray structural and molecular modeling studies, (1)H NMR, UV-vis spectroscopy, electrochemistry studies, and fluorescence quenching data support the formation of a strong complex between the new ligand and the metal center of ZnTPP. On the basis of computational studies, the highest occupied molecular orbital (HOMO) of this ligand is significantly different from a model compound with insulating carbons between the pyridine and the fullerene. The N-pyridinium fulleropyrrolidine salts of the new ligand and model compound were also prepared and their spectral and electrochemical properties are reported. PMID:15230581

  1. Modeling Nanotube Caps: The Relationship Between Fullerenes and Caps.

    PubMed

    Melle-Franco, Manuel; Brinkmann, Gunnar; Zerbetto, Francesco

    2015-12-24

    We present a novel method to calculate energies of nanotube caps with different levels of accuracy and a comprehensive study of its application to the IPR caps of the (10,0) carbon nanotube. The two most stable caps for (10,0) have 42 atoms, an energy of 8.7 eV, and correspond to sections of the third most abundant fullerene, C84. These caps are isoenergetic with a chemically unstable cap with 40 carbon atoms related to a C80 isomer that is also chemically unstable. Energies for the other caps are between 9.3 and 10 eV. A method to calculate cap energetics with fullerenes with an error less than 3% is also presented. PMID:26654289

  2. Interface engineering for efficient fullerene-free organic solar cells

    NASA Astrophysics Data System (ADS)

    Shivanna, Ravichandran; Rajaram, Sridhar; Narayan, K. S.

    2015-03-01

    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.

  3. Ion bombardment and its effects on the optical properties of metals

    NASA Technical Reports Server (NTRS)

    Anderson, D. L.

    1964-01-01

    An experimental program, to evaluate the change in total hemispherical emittance and solar absorptance of engineering metals used on spacecraft and in spacecraft instrumentation systems, is presented. Three materials, titanium alloy, pure aluminum, and electrolytic copper, were used in the experiment. Results show that emittance, absorptance, and alpha/epsilon ratio of the materials were changed by ion bombardment. The time before the change occurs depends upon the material used, the intensity of bombardment, and the environment assumed.

  4. Understanding charge transfer in carbon nanotube-fullerene bulk heterojunctions.

    PubMed

    Gong, Maogang; Shastry, Tejas A; Cui, Qiannan; Kohlmeyer, Ryan R; Luck, Kyle A; Rowberg, Andrew; Marks, Tobin J; Durstock, Michael F; Zhao, Hui; Hersam, Mark C; Ren, Shenqiang

    2015-04-01

    Semiconducting single-walled carbon nanotube/fullerene bulk heterojunctions exhibit unique optoelectronic properties highly suitable for flexible, efficient, and robust photovoltaics and photodetectors. We investigate charge-transfer dynamics in inverted devices featuring a polyethylenimine-coated ZnO nanowire array infiltrated with these blends and find that trap-assisted recombination dominates transport within the blend and at the active layer/nanowire interface. We find that electrode modifiers suppress this recombination, leading to high performance. PMID:25797180

  5. 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.

  6. A highly efficient fullerene acceptor for polymer solar cells.

    PubMed

    He, Dan; Zuo, Chuantian; Chen, Shan; Xiao, Zuo; Ding, Liming

    2014-04-28

    C70-based acceptors show great potential in polymer solar cells (PSCs). Two high-LUMO C70 acceptors, the 66π OQMF70 and the 64π bis-OQMF70, based on methano[70]fullerene (C70CH2) were developed. An outstanding power conversion efficiency (PCE) of 6.88% was obtained from OQMF70:P3HT solar cells. PMID:24626781

  7. 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.

  8. 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.

  9. Characterisation and determination of fullerenes: A critical review.

    PubMed

    Astefanei, Alina; Núñez, 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

  10. Nanoscale fullerene compression of an yttrium carbide cluster.

    PubMed

    Zhang, Jianyuan; Fuhrer, Tim; Fu, Wujun; Ge, Jiechao; Bearden, Daniel W; Dallas, Jerry; Duchamp, James; Walker, Kenneth; Champion, Hunter; Azurmendi, Hugo; Harich, Kim; Dorn, Harry C

    2012-05-23

    The nanoscale parameters of metal clusters and lattices have a crucial influence on the macroscopic properties of materials. Herein, we provide a detailed study on the size and shape of isolated yttrium carbide clusters in different fullerene cages. A family of diyttrium endohedral metallofullerenes with the general formula of Y(2)C(2n) (n = 40-59) are reported. The high field (13)C nuclear magnetic resonance (NMR) and density functional theory (DFT) methods are employed to examine this yttrium carbide cluster in certain family members, Y(2)C(2)@D(5)(450)-C(100), Y(2)C(2)@D(3)(85)-C(92), Y(2)C(2)@C(84), Y(2)C(2)@C(3v)(8)-C(82), and Y(2)C(2)@C(s)(6)-C(82). The results of this study suggest that decreasing the size of a fullerene cage with the same (Y(2)C(2))(4+) cluster results in nanoscale fullerene compression (NFC) from a nearly linear stretched geometry to a constrained "butterfly" structure. The (13)C NMR chemical shift and scalar (1)J(YC) coupling parameters provide a very sensitive measure of this NFC effect for the (Y(2)C(2))(4+) cluster. The crystal structural parameters of a previously reported metal carbide, Y(2)C(3) are directly compared to the (Y(2)C(2))(4+) cluster in the current metallofullerene study. PMID:22497289

  11. 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.

  12. 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.

  13. Tunneling spectroscopy of multi-shell carbon fullerenes

    NASA Astrophysics Data System (ADS)

    Doore, Keith; Cook, Matt; Clausen, Eric; Kidd, Tim; Ye, Zhipeng; Ye, Gaihua; He, Rui; Stollenwerk, Andrew

    Carbon allotropes such as fullerenes and nanotubes have generated considerable interest due possible exploitation of their mechanical and electrical properties for practical applications. Carbon onions are a type of fullerene consisting of multiple spherically concentric shells of curved graphitic sheets. Compared to single-shell fullerenes, few studies have been directed toward understanding the structural and electrical properties of carbon onions. Because carbon onions have proven difficult to fabricate in a controlled method, most of these studies have focused on synthesis methods. In this study, we investigate the electrical properties of carbon onions using a scanning tunneling microscope. Carbon onions were fabricated using ultrasonic agitation to break down isopropanol facilitated by a MoS2 catalyst. Particles suspended in the remaining solution were deposited onto atomically flat HOPG substrates. Scanning tunneling spectroscopy indicate that carbon onions can exhibit both metallic and semiconducting properties, similar to carbon nanotubes. This work was supported in part by the National Science Foundation, Grants No. DMR-1206530 and No. DMR-1410496.

  14. 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

  15. 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.

  16. Continuous symmetry of C60 fullerene and its derivatives.

    PubMed

    Sheka, E F; Razbirin, B S; Nelson, D K

    2011-04-21

    Conventionally, the I(h) symmetry of fullerene C(60) is accepted, which is supported by numerous calculations. However, this conclusion results from the consideration of the molecule electron system, of its odd electrons in particular, in a closed-shell approximation without taking the electron spin into account. Passing to the open-shell approximation has led to both the energy and the symmetry lowering up to C(i). Seemingly contradicting to a high-symmetry pattern of experimental recording, particularly concerning the molecule electronic spectra, the finding is considered in this Article from the continuous symmetry viewpoint. Exploiting continuous symmetry measure and continuous symmetry level approaches, it was shown that formal C(i) symmetry of the molecule is by 99.99% I(h). A similar continuous symmetry analysis of the fullerene monoderivatives gives a reasonable explanation of a large variety of their optical spectra patterns within the framework of the same C(1) formal symmetry exhibiting a strong stability of the C(60) skeleton. TOC color pictures present chemical portrait of C(60) in terms of atomic chemical susceptibility (Sheka, E. Fullerenes: Nanochemistry, Nanomagnetism, Nanomedicine, Nanophotonics; CRC Press: Taylor and Francis Group, Boca Raton, 2011). PMID:21449547

  17. 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

  18. 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.

  19. 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

  20. 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

  1. Ion bombardment glow-discharge furnaces for atomic emission spectroscopy

    SciTech Connect

    Tanguay, S.L.

    1990-01-01

    Two glow discharge plasma devices for the atomic emission analysis of aqueous samples were investigated. The devices use thermal vaporization of samples from a graphite cathode coupled with glow-discharge excitation. Furnace heating of the cathode is accomplished by the positive ion bombardment of the cathode during plasma operation. The dc plasma operates in Ar at 0.5-5.0 torr, with currents up to 250 mA. A cw, axial magnetic field of up to 1.25 kG is applied to the cylindrical-post cathode system to reduce electron losses, thereby increasing plasma excitation and ionization efficiency. At higher currents, the cathodes heat to temperatures as high as 2,500{degree}C in the case of the cylindrical-post cathode. Hollow-cathode heating temperatures are lower under comparable conditions, due to the larger cathode surface area, greater cathode mass, and lower power dissipation. The peak furnace temperature using this configuration is approximately 2100{degree}C. The role of the emission of thermionic electrons from the hot cathodes in limiting the cathode heating and in regulating the cathode temperature are considered. Sample residues of up to 50 ng of the analyte are vaporized from the cylindrical-post cathode within a few seconds of the initiation of the discharge, resulting in a transient emission intensity profile. With the hollow-cathode furnace, vaporization may take several seconds. Although a lower rate of cathode heating and a lower sample vapor residence time results in limits of detection which are one to two orders of magnitude lower than those achieved using the cylindrical-post cathode system. For the hollow cathode, limits of detection are on the order of 10 pg to 1 ng.

  2. 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 cathode’s 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 6μs 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.

  3. 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.

  4. 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.

  5. Conformationally Constrained Macrocyclic Diporphyrin-Fullerene Artificial Photosynthetic Reaction Center

    PubMed Central

    Garg, Vikas; Kodis, Gerdenis; Chachisvilis, Mirianas; Hambourger, Michael; Moore, Ana L.; Moore, Thomas A.; Gust, Devens

    2011-01-01

    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 semi-empirical 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. PMID:21319796

  6. 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.

  7. 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.

  8. 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) ...

  9. 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...

  10. 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...

  11. 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.

  12. 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; Schröder, Martin

    2014-01-01

    Summary A series of six fullerene–linker–fullerene 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 electron–electron interactions in the electrochemically generated dianions of these triads, with one electron per fullerene cage were studied by EPR spectroscopy. The nature of electron–electron 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 spin–spin coupling with triplet character, while in the longer terephthalate-bridged triads the intramolecular spin–spin coupling is significantly reduced. PMID:24605154

  13. 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.

  14. Computational studies of the binding mechanisms of fullerenes to human serum albumin.

    PubMed

    Li, Jinyu; Jiang, Lizhi; Zhu, Xiaolei

    2015-07-01

    Fullerene and its derivatives show promising prospects for applications in a vast array of biological systems. A key aspect concerning their biomedical applications is how they interact with proteins from molecular levels, which is still poorly understood. In the current study, we investigated the structural and thermodynamic basis of the interactions between two pharmacologically relevant fullerene derivatives and human serum albumin (HSA) using molecular docking, molecular dynamics simulations, and binding free energy calculations. Our results demonstrate that fullerenes steadily bind with HSA at the interfacial cavity formed by subdomains IIA and IIIA. In agreement with available experimental data, our simulations show that the global structure of HSA becomes more compact in the presence of fullerene, while local structural dynamics of the binding cavity behaves diversely depending on the chemical properties of bound fullerenes. Binding free energy calculations confirmed that the interactions between fullerenes and HSA are dominantly stabilized by van der Waals forces and they further allowed the identification of key residues involved in fullerene binding. The structural and energetic insights obtained from this work may help for the development of fullerene-based drug delivery devices and therapeutic agents with improved biological profile. PMID:26093686

  15. 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.

  16. 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.

  17. Charge stabilization in a closely spaced ferrocene-boron dipyrrin-fullerene triad.

    PubMed

    Wijesinghe, Channa A; El-Khouly, Mohamed E; Blakemore, James D; Zandler, Melvin E; Fukuzumi, Shunichi; D'Souza, Francis

    2010-05-21

    New molecular triads composed of closely spaced ferrocene-boron dipyrrin-fullerene, 1 and triphenylamine-boron dipyrrin-fullerene, 2 are synthesized, and photoinduced electron transfer leading to charge stabilization is demonstrated using a femtosecond transient spectroscopic technique. PMID:20442893

  18. 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...

  19. 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

  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. Polarisation charge switching through the motion of metal atoms trapped in fullerene cages.

    PubMed

    Raggi, G; Stace, A J; Bichoutskaia, E

    2014-11-21

    The formation of an endohedral fullerene can lead to charge transfer and the generation of a trapped positively charged metal ion. Using Ca@C60 and [Ca@C60](+) endohedral fullerenes as models, density functional theory calculations predict that the motion of a calcium ion within a fullerene is accompanied by large changes in electron density on the surrounding carbon cage. In the case of [Ca@C60](+), partial atomic charge distribution on the carbon cage is split between hemispheres into regions of positive and negative charge as Ca(n+) moves inside the fullerene cage (non-integer n strongly depends on position of the ion). It is proposed that within tethered fullerene cages the movement of partial atomic charge could form the bases of a molecular polarisation storage bit, and that adopted in the form of [Ca@C60](+) the presence of an overall charge may offer a route to either optical or electronic control. PMID:25272966

  2. Preparation of macrocycles with high carbon content: Toward the synthesis of endohedral metal fullerene complexes

    SciTech Connect

    Parker, T.C.; Rubin, Y.

    1995-12-31

    This research is focused on the synthesis of macrocycles with high carbon content for the purpose of total synthesis of fullerenes or fullerene-like structures with the ultimate goal of obtaining endohedral metal complexes of fullerene C{sub 60}. Toward this goal, the authors have utilized organometallic chemistry to synthesize novel cyclophanes such as 1 which are constituted primarily of acetylenic units. The authors believe such macrocycles may be C{sub 60} precursors since studies have shown that acetylenic macrocycles form fullerenes in the gas phase. The authors have synthesized macrocycle 1 using a highly convergent route from commercially available starting materials. The macrocycle 1 is produced from copper (I) catalyzed coupling of 2 which is obtained in turn by the coupling of the copper acetylide 3 with 4. The suitability of macrocycles such as 1 for fullerene precursors is currently under investigation.

  3. Evolution of plasmonic and hybrid photoionization properties of alkaline earth metallofullerenes with the increasing fullerene size

    NASA Astrophysics Data System (ADS)

    Patel, Aakash; Chakraborty, Himadri

    2013-05-01

    A theoretical study of the photoionization of endohedral fullerenes with a selection of fullerene molecules of increasing size and with confined alkaline earth atoms like Be and Mg is carried out. The fullerene ion cores, comprised of C4+ ions, are smudged into a continuous jellium charge distribution, while the delocalized cloud of carbon valence electrons plus the electrons of the encaged atom are treated in the Kohn-Sham local density approximation (LDA). Only the spherical geometry is considered. The photoionization spectra are calculated by the time-dependent LDA that includes essential electron correlations. A systematic evolution of the mixing of valence atomic levels with states of fullerene single-electron bands is found along the sequence. This hybridization as a function of the fullerene size is seen to primarily define the properties of the subshell-differential ionization spectra both in the low energy plasmonic as well as the high energy oscillatory regions. Supported by NSF and DOE.

  4. 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.

  5. Adverse effects of fullerenes (nC60) spiked to sediments on Lumbriculus variegatus (Oligochaeta).

    PubMed

    Pakarinen, K; Petersen, E J; Leppänen, M T; Akkanen, J; Kukkonen, J V K

    2011-12-01

    Effects of fullerene-spiked sediment on a benthic organism, Lumbriculus variegatus (Oligochaeta), were investigated. Survival, growth, reproduction, and feeding rates were measured to assess possible adverse effects of fullerene agglomerates produced by water stirring and then spiked to a natural sediment. L. variegatus were exposed to 10 and 50 mg fullerenes/kg sediment dry mass for 28 d. These concentrations did not impact worm survival or reproduction compared to the control. Feeding activities were slightly decreased for both concentrations indicating fullerenes' disruptive effect on feeding. Depuration efficiency decreased in the high concentration only. Electron and light microscopy and extraction of the worm fecal pellets revealed fullerene agglomerates in the gut tract but not absorption into gut epithelial cells. Micrographs also indicated that 16% of the epidermal cuticle fibers of the worms were not present in the 50 mg/kg exposures, which may make worms susceptible to other contaminants. PMID:21852027

  6. [Effect of C60 fullerene on viscoelastic properties of human erythrocytes membrane].

    PubMed

    Shpakova, N M; Nipot, O S; Ishchenko, I O; Pryluts'ka, S V; Bohuts'ka, K I; Cherepanov, V V; Sandomyrs'kyĭ, B P; Pryluts'kyĭ, Iu I

    2014-01-01

    The effect of C60 fullerene aqueous colloid solution (C60FAS) on viscoelastic properties of human erythrocytes membrane has been studied. It was established that the effect of C60FAS on erythrocytes depends on the medium osmolality and concentration of C60 fullerene in it. In particular, in isotonic solution (0,15 mol/l NaCl) adding C60 fullerene in concentrations from 0,7 to 28 μmol/l did not cause the hemolytic damage of cells. In hypotonic medium when introducing C60 fullerene (7 μmol/l concentration) at the beginning of erythrocyte hemolysis its stimulating effect was maximal and when adding C60FAS in 20 s after hemolysis start no this process stimulation is observed. This points to the changes in viscoelastic properties of erythrocyte membranes even during the first seconds of its interaction with C60 fullerene. PMID:25566674

  7. Interaction between fullerene halves Cn (n ≤ 40) and single wall carbon nanotube

    NASA Astrophysics Data System (ADS)

    Sharma, Amrish; Kaur, Sandeep; Mudahar, Isha

    2016-05-01

    We have investigated the structural and electronic properties of carbon nanotube with small fullerene halves Cn (n ≤ 40) which are covalently bonded to the side wall of an armchair single wall carbon nanotube (SWCNT) using first principle method based on density functional theory. The fullerene size results in weak bonding between fullerene halves and carbon nanotube (CNT). Further, it was found that the C-C bond distance that attaches the fullerene half and CNT is of the order of 1.60 Å. The calculated binding energies indicate the stability of the complexes formed. The HOMO-LUMO gaps and electron density of state plots points towards the metallicity of the complex formed. Our calculations on charge transfer reveal that very small amount of charge is transferred from CNT to fullerene halves.

  8. The interactions of high-energy, highly-charged ions with fullerenes

    SciTech Connect

    Ali, R.; Berry, H.G.; Cheng, S.

    1996-03-01

    In 1985, Robert Curl and Richard Smalley discovered a new form of carbon, the fullerene, C{sub 60}, which consists of 60 carbon atoms in a closed cage resembling a soccer ball. In 1990, Kritschmer et al. were able to make macroscopic quantities of fullerenes. This has generated intense activity to study the properties of fullerenes. One area of research involves collisions between fullerenes and atoms, ions or electrons. In this paper we describe experiments involving interactions between fullerenes and highly charged ions in which the center-of-mass energies exceed those used in other work by several orders of magnitude. The high values of projectile velocity and charge state result in excitation and decay processes differing significantly from those seen in studies 3 at lower energies. Our results are discussed in terms of theoretical models analogous to those used in nuclear physics and this provides an interesting demonstration of the unity of physics.

  9. Localization of the valence electron of endohedrally confined hydrogen, lithium and sodium in fullerene cages

    NASA Astrophysics Data System (ADS)

    Cuestas, Eloisa; Serra, Pablo

    2016-03-01

    The localization of the valence electron of H, Li and Na atoms enclosed by three different fullerene molecules is studied. The structure of the fullerene molecules is used to calculate the equilibrium position of the endohedrally atom as the minimum of the classical (N + 1)-body Lennard-Jones potential. Once the position of the guest atom is determined, the fullerene cavity is modeled by a short range attractive shell according to molecule symmetry, and the enclosed atom is modeled by an effective one-electron potential. In order to examine whether the endohedral compound is formed by a neutral atom inside a neutral fullerene molecule X@CN or if the valence electron of the encapsulated atom localizes in the fullerene giving rise to a state with the form X+@CN‑, we analyze the electronic density, the projections onto free atomic states and the weights of partial angular waves.

  10. Comparison of geometric, electronic, and vibrational properties for isomers of small fullerenes C20-C36.

    PubMed

    Małolepsza, Edyta; Witek, Henryk A; Irle, Stephan

    2007-07-26

    We employ the self-consistent-charge density-functional tight-binding (SCC-DFTB) method for computing geometric, electronic, and vibrational properties for various topological isomers of small fullerenes. We consider all 35 five- and six-member rings containing isomers of small fullerenes, C20, C24, C26, C28, C30, C32, C34, and C36, as first part of a larger effort to catalog CC distance distributions, valence CCC angle distributions, electronic densities of states (DOSs), vibrational densities of states (VDOSs), and infrared (IR) and Raman spectra for fullerenes C20-C180. Common features among the fullerenes are identified and properties characteristic for each specific fullerene isomer are discussed. PMID:17429953

  11. Compact, maintainable 80-KeV neutral beam module

    DOEpatents

    Fink, Joel H.; Molvik, Arthur W.

    1980-01-01

    A compact, maintainable 80-keV arc chamber, extractor module for a neutral beam system immersed in a vacuum of <10.sup.-2 Torr, incorporating a nested 60-keV gradient shield located midway between the high voltage ion source and surrounding grounded frame. The shield reduces breakdown or arcing path length without increasing the voltage gradient, tends to keep electric fields normal to conducting surfaces rather than skewed and reduces the peak electric field around irregularities on the 80-keV electrodes. The arc chamber or ion source is mounted separately from the extractor or ion accelerator to reduce misalignment of the accelerator and to permit separate maintenance to be performed on these systems. The separate mounting of the ion source provides for maintaining same without removing the ion accelerator.

  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. 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

  14. 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.

  15. 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; Stobiński, 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

  16. 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 derivatives–carboxyfullerenes–exhibits a strong free radical scavenging capacity. The permeation of C60-fullerene and its amphiphilic derivatives–C3-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

  17. 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.

  18. 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.

  19. 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.

  20. 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).

  1. 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.

  2. Functionalized fullerene (C₆₀) 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

  3. 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…

  4. Origin of 200-keV interplanetary electrons.

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Cline, T. L.; Fisk, L. A.

    1972-01-01

    The suggestion by Lin et al. (1972) that a distinct spectral feature exists at about 200 keV, which could be due to a neutron-decay electron component of either solar or galactic origin, is examined. Alternative sources models, including production by nearby galactic objects or acceleration at the outer boundary of the solar system, are also considered.

  5. 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

  6. 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

  7. Hyperdiamond and hyperlonsdaleit: Possible crystalline phases of fullerene C28

    NASA Astrophysics Data System (ADS)

    Seifert, Gotthard; Enyashin, Andrey N.; Heine, Thomas

    2005-07-01

    Structures, energies of formation, electronic spectra and values of bulk moduli for crystalline modifications of small fullerene C28 with space groups Fd3m and P63/mmc are calculated at the density-functional based tight-binding level. Both solid phases of C28 have very similar characteristics, which are compared with those of crystals of other small fullerenes— C20 and C36 . The important role of π component of the C-C bounds on the properties are shown.

  8. Synthesis of endohedral iron-fullerenes by ion implantation

    NASA Astrophysics Data System (ADS)

    Minezaki, H.; Ishihara, S.; Uchida, T.; Muramatsu, M.; Rácz, R.; Asaji, T.; Kitagawa, A.; Kato, Y.; Biri, S.; Yoshida, Y.

    2014-02-01

    In this paper, we discuss the results of our study of the synthesis of endohedral iron-fullerenes. A low energy Fe+ ion beam was irradiated to C60 thin film by using a deceleration system. Fe+-irradiated C60 thin film was analyzed by high performance liquid chromatography and laser desorption/ ionization time-of-flight mass spectrometry. We investigated the performance of the deceleration system for using a Fe+ beam with low energy. In addition, we attempted to isolate the synthesized material from a Fe+-irradiated C60 thin film by high performance liquid chromatography.

  9. Synthesis of endohedral iron-fullerenes by ion implantation.

    PubMed

    Minezaki, H; Ishihara, S; Uchida, T; Muramatsu, M; Rácz, R; Asaji, T; Kitagawa, A; Kato, Y; Biri, S; Yoshida, Y

    2014-02-01

    In this paper, we discuss the results of our study of the synthesis of endohedral iron-fullerenes. A low energy Fe(+) ion beam was irradiated to C60 thin film by using a deceleration system. Fe(+)-irradiated C60 thin film was analyzed by high performance liquid chromatography and laser desorption/ ionization time-of-flight mass spectrometry. We investigated the performance of the deceleration system for using a Fe(+) beam with low energy. In addition, we attempted to isolate the synthesized material from a Fe(+)-irradiated C60 thin film by high performance liquid chromatography. PMID:24593524

  10. Electron pair escape from fullerene cage via collective modes.

    PubMed

    Schüler, Michael; Pavlyukh, Yaroslav; Bolognesi, Paolo; Avaldi, Lorenzo; Berakdar, Jamal

    2016-01-01

    Experiment and theory evidence a new pathway for correlated two-electron release from many-body compounds following collective excitation by a single photon. Using nonequilibrium Green's function approach we trace plasmon oscillations as the key ingredient of the effective electron-electron interaction that governs the correlated pair emission in a dynamic many-body environment. Results from a full ab initio implementation for C60 fullerene are in line with experimental observations. The findings endorse the correlated two-electron photoemission as a powerful tool to access electronic correlation in complex systems. PMID:27086559

  11. Electron pair escape from fullerene cage via collective modes

    PubMed Central

    Schüler, Michael; Pavlyukh, Yaroslav; Bolognesi, Paolo; Avaldi, Lorenzo; Berakdar, Jamal

    2016-01-01

    Experiment and theory evidence a new pathway for correlated two-electron release from many-body compounds following collective excitation by a single photon. Using nonequilibrium Green’s function approach we trace plasmon oscillations as the key ingredient of the effective electron-electron interaction that governs the correlated pair emission in a dynamic many-body environment. Results from a full ab initio implementation for C60 fullerene are in line with experimental observations. The findings endorse the correlated two-electron photoemission as a powerful tool to access electronic correlation in complex systems. PMID:27086559

  12. Extraction and purification of fullerenes: A comprehensive review

    SciTech Connect

    Theobald, J.; Perrut, M.; Weber, J.V.

    1995-08-01

    This review summarizes the advances of the last four years in the field of fullerenes purification. Purification involves extraction from soots, which may be considered as a prepurification step, and separation by liquid chromatography, where the different stationary phases tested are listed. The authors also describe other purification techniques, like elution on molecular sieves or activated charcoal, gel permeation, and supercritical fluids purification. The authors purpose is to show the reader the general trends for obtaining pure C{sub 60} and C{sub 70}.

  13. Synthesis of endohedral iron-fullerenes by ion implantation

    SciTech Connect

    Minezaki, H.; Ishihara, S.; Uchida, T.; Muramatsu, M.; Kitagawa, A.; Rácz, R.; Biri, S.; Kato, Y.; Yoshida, Y.; Bio-Nano Electronics Research Centre, Toyo University, 2100, Kujirai, Kawagoe, Saitama 350-8585

    2014-02-15

    In this paper, we discuss the results of our study of the synthesis of endohedral iron-fullerenes. A low energy Fe{sup +} ion beam was irradiated to C{sub 60} thin film by using a deceleration system. Fe{sup +}-irradiated C{sub 60} thin film was analyzed by high performance liquid chromatography and laser desorption/ ionization time-of-flight mass spectrometry. We investigated the performance of the deceleration system for using a Fe{sup +} beam with low energy. In addition, we attempted to isolate the synthesized material from a Fe{sup +}-irradiated C{sub 60} thin film by high performance liquid chromatography.

  14. Electrically conducting porphyrin and porphyrin-fullerene electropolymers

    DOEpatents

    Gust, Jr., John Devens; Liddell, Paul Anthony; Gervaldo, Miguel Andres; Bridgewater, James Ward; Brennan, Bradley James; Moore, Thomas Andrew; Moore, Ana Lorenzelli

    2014-03-11

    Compounds with aryl ring(s) at porphyrin meso position(s) bearing an amino group in position 4 relative to the porphyrin macrocycle, and at least one unsubstituted 5 (hydrogen-bearing) meso position with the 10-, 15-, and/or 20-relationship to the aryl ring bearing the amino group, and metal complexes thereof, feature broad spectral absorption throughout the visible region. These compounds are electropolymerized to form electrically conducting porphyrin and porphyrin-fullerene polymers that are useful in photovoltaic applications. The structure of one such electrically conducting porphyrin polymer is shown below. ##STR00001##

  15. Diamond-like phases formed from fullerene-like clusters

    NASA Astrophysics Data System (ADS)

    Belenkov, E. A.; Greshnyakov, V. A.

    2015-11-01

    The geometrically optimized structure and properties of thirteen diamond-like carbon phases formed by linking or combining fullerene-like clusters (C4, C6, C8, C12, C16, C24, or C48) have been investigated. Atoms in the structures of these phases are located in crystallographically equivalent positions. The calculations have been performed using the density functional theory in the generalized gradient approximation. The calculated values of the structural characteristics and properties (sublimation energies, bulk moduli, band gaps, X-ray diffraction patterns) of the studied diamond-like phases differ significantly from the corresponding values for cubic diamond.

  16. An experiment to study fullerene formation under reduced gravity

    NASA Technical Reports Server (NTRS)

    Wdowiak, Thomas J.

    1992-01-01

    The activity of the summer focused on the design and construction of key components of a carbon arc/inert gas reactor for fullerene production, that is suitable for reduced gravity experiments onboard the KC-135 aircraft. The apparatus will be configured for both floor-mount and free-floating operation providing access to reduction to 10(exp -2) and 10(exp -3) of normal respectively. It is planned to incorporate 'seat belt' restraints that will allow a safe transition from reduced gravity free-float to full gravity, at the end of the parabolic.

  17. Electron pair escape from fullerene cage via collective modes

    NASA Astrophysics Data System (ADS)

    Schüler, Michael; Pavlyukh, Yaroslav; Bolognesi, Paolo; Avaldi, Lorenzo; Berakdar, Jamal

    2016-04-01

    Experiment and theory evidence a new pathway for correlated two-electron release from many-body compounds following collective excitation by a single photon. Using nonequilibrium Green’s function approach we trace plasmon oscillations as the key ingredient of the effective electron-electron interaction that governs the correlated pair emission in a dynamic many-body environment. Results from a full ab initio implementation for C60 fullerene are in line with experimental observations. The findings endorse the correlated two-electron photoemission as a powerful tool to access electronic correlation in complex systems.

  18. Role of pressure in the study of fullerenes

    SciTech Connect

    Schirber, J.E.; Samara, G.A.; Morosin, B.; Assink, R.; Loy, D.; Wang, H.; Williams, J.; Murphy, D.; Kortan, A.R.; Rossiensky, M.; Zhou, O.; Zhu, Q.; Kniaz, K.; Fischer, J.E.

    1993-08-01

    Although fullerenes and their compounds are very new and exhibit new phenomena, pressure has already been an important factor in the characterization and study of these materials. In order to illustrate this, the authors will review collaborative studies on: (i) the effect of pressure on alkali and alkaline earth doped C{sub 60} superconductors, (ii) the effect of pressure and pressure medium on the ordering temperature of C{sub 60}, and (iii) the role of pressure in the study of the feasibility of using C{sub 60} as ``lattice sieves`` for separation of gases.

  19. Influence of organic ions on DNA damage induced by 1 eV to 60 keV electrons

    NASA Astrophysics Data System (ADS)

    Zheng, Yi; Sanche, Léon

    2010-10-01

    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 (˜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.

  20. Influence of organic ions on DNA damage induced by 1 eV to 60 keV electrons.

    PubMed

    Zheng, Yi; Sanche, Léon

    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 (∼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. PMID:20969428

  1. 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.

  2. Electro-chemo-mechanical characteristics of fullerene-reinforced ionic polymer-metal composite transducers

    NASA Astrophysics Data System (ADS)

    Oh, Il-Kwon; Jung, Jung-Hwan; Jeon, Jin-Han; Vadahanambi, Sridhar

    2010-07-01

    In this paper, the effects of fullerene as a reinforcing agent in Nafion-based ionic polymer-metal composite transducers were investigated in view of the electro-chemo-mechanical characteristics including sensing capabilities, specific electro-mechanical energy efficiency and blocking forces. Substantial variation in the crystallinity of fullerene-Nafion membranes even with the addition of low concentrations was observed in the x-ray diffraction data. The flower-like fullerene agglomerations observed in the scanning electron microscope images of the direct mixing samples between fullerenes and Nafion disappeared in the present solvent recasting method and good dispersions of fullerenes in the Nafion matrix were observed in the atomic force microscopy images. The Fourier transform infrared spectroscopy in conjunction with its complementary x-ray photon spectroscopy showed strong electrostatic and chemical interactions between fullerenes and sulfonated moieties of Nafion. Present results show that the 0.5 wt% fullerene-reinforced ionic polymer-metal composite transducer shows nearly three times the blocking force, twice the tip displacement, three times the sensed voltage and three times the electro-mechanical energy efficiency in comparison with a pure Nafion-based IPMC transducer.

  3. Fullerenes, PAH, Carbon Nanostructures, and Soot in Low Pressure Diffusion Flames

    NASA Technical Reports Server (NTRS)

    Grieco, William J.; Lafleur, Arthur L.; Rainey, Lenore C.; Taghizadeh, Koli; VanderSande, John B.; Howard, Jack B.

    1997-01-01

    The formation of fullerenes C60 and C7O is known to occur in premixed laminar benzene/oxygen/argon flames operated at reduced pressures. High resolution transmission electron microscopy (HRTEM) images of material collected from these flames has identified a variety of multishelled nanotubes and fullerene 'onions' as well as some trigonous structures. These fullerenes and nanostructures resemble the material that results from commercial fullerene production systems using graphite vaporization. As a result, combustion is an interesting method for fullerenes synthesis. If commercial scale operation is to be considered, the use of diffusion flames might be safer and less cumbersome than premixed flames. However, it is not known whether diffusion flames produce the types and yields of fullerenes obtained from premixed benzene/oxygen flames. Therefore, the formation of fullerenes and carbon nanostructures, as well as polycyclic aromatic hydrocarbons (PAH) and soot, in acetylene and benzene diffusion flames is being studied using high performance liquid chromatography (HPLC) and high resolution transmission electron microscopy (HRTEM).

  4. The studies on the aromaticity of fullerenes and their holmium endohedral compounds.

    PubMed

    Tan, Bisheng; Peng, Rufang; Li, Hongbo; Wang, Bing; Jin, Bo; Chu, Shijin; Long, Xinping

    2011-02-01

    Density functional theory BLYP/DNP was employed to optimize a series of fullerenes and their holmium endohedral compounds, including C(20), Ho@C(20), Ho(3+)@C(20), C(60), Ho@C(60), Ho(3+)@C(60),C(70), Ho@C(70), Ho(3+)@C(70) C(78), Ho@C(78), Ho(3+)@C(78), C(82),Ho@C(82) and Ho(3+)@C(82). DFT semi core pseudospot approximation was taken into consideration in the calculations of the element holmium because of its particular electronic structure. Fullerenes and their holmium endohedral compounds' aromaticity were studied in terms of structural criteria, energetic criteria, and reactivity criteria. The results indicate that the aromaticity of fullerenes was reduced when a holmium atom was introduced into the carbon cage, and the endohedral fullerenes' reactive activity enhance; but the aromaticity of the carbon cage increased when a Ho(3+) cation was encapsulated into a fullerene. Calculations of aromaticity and stability indicate that two paths can lead to the similar aim of preparing holmium endohedral fullerenes; that is, they can form from either a holmium atom or a holmium cation (Ho(3+)) reacting with fullerenes, respectively, and the latter is more favorable. PMID:20443036

  5. Donor-acceptor type co-crystals of arylthio-substituted tetrathiafulvalenes and fullerenes.

    PubMed

    Lu, Xiaofeng; Sun, Jibin; Zhang, Shangxi; Ma, Longfei; Liu, Lei; Qi, Hui; Shao, Yongliang; Shao, Xiangfeng

    2015-01-01

    A series of donor-acceptor type co-crystals of fullerene (as the acceptor) and arylthio-substituted tetrathiafulvalene derivatives (Ar-S-TTF, as the donor) were prepared and their structural features were thoroughly investigated. The formation of co-crystals relies on the flexibility of Ar-S-TTF and the size matches between Ar-S-TTF and fullerene. Regarding their compositions, the studied co-crystals can be divided into two types, where types I and II have donor:acceptor ratios of 1:1 and 1:2, respectively. Multiple intermolecular interactions are observed between the donor and acceptor, which act to stabilize the structures of the resulting co-crystals. In the type I co-crystals, the fullerene molecule is surrounded by four Ar-S-TTF molecules, that is, two Ar-S-TTF molecules form a sandwich structure with one fullerene molecule and the other two Ar-S-TTF molecules interact with the fullerene molecule along their lateral axes. In the type II co-crystals, one fullerene molecule has the donor-acceptor mode similar to that in type I, whereas the other fullerene molecule is substantially surrounded by the aryl groups on Ar-S-TTF molecules and the solvent molecules. PMID:26199659

  6. Potential energy of H2 inside the C116 fullerene dimerization: An atomic analysis

    NASA Astrophysics Data System (ADS)

    EL-Barbary, A. A.

    2016-05-01

    DFT method has proved useful for its ability to provide an atomic analysis of the dimerization of fullerene molecules. Such atomic analysis may provide information that is not available by experimental methods. Here, the structures of possible three isomers of C116 fullerene dimerization obtained from two C58 fullerene cages have been optimized using DFT method at the B3LYP/6-31G(d,p) level of theory. The orientation of C58 fullerene and bond reorganization during the dimerization process have been studied. The transition structures and energy barriers between the three isomers are obtained. The potential energies of the H2 molecule motion along and perpendicular to the axial dimer with possible rotational angles are calculated. Also, the 13C NMR chemical shifts and electron density distribution have been applied to distinguish between the C58 fullerene cages and the three isomers of C116 fullerene dimerization. Our results show that the C116 fullerene dimerization could be considered to be good candidate for hydrogen storage.

  7. Functionalization of pentagon-pentagon edges of fullerenes by cyclic polysulfides: A DFT study

    NASA Astrophysics Data System (ADS)

    Anafcheh, Maryam; Khodadadi, Zahra; Ektefa, Fatemeh; Ghafouri, Reza

    2016-05-01

    We have performed a computational study to investigate the cyclosulfurization of the pentagon-pentagon (p-p) junctions in the non-IPR fullerenes C60(D3) and C70(C2v), and also Stone-Wales defective C60 fullerene. Our results indicate the exothermic character of cyclosulfurization processes which can be related to the increase of pyramidalization angle (spherical excesses) and p characters of natural hybrid orbitals of C atoms at the p-p junctions. In fact these lead to the structural strain relief and stability of the cyclosulfurization derivatives of the non-IPR fullerenes. Moreover, the cyclosulfurization reaction of p-p bonds on the C70(C2v) is more energetically favorable than that of C60(D3), due to the higher curvature of carbon sites and the larger values of the p characters of natural hybrid orbitals in the C70(C2v). On the other hand, localization of the excess electrons on the C atoms at the p-p junctions leads to the low tendency of the charged non-IPR fullerenes to cyclosulfurization process. The desulfurization pathway of the exohedral derivatives of C70(C2v) indicates that it is energetically unfavorable for the functionalized fullerenes to break into individual fullerene and sulfur molecules. HOMO-LUMO gaps almost are independent of the number of pentathiepin rings while sensitive to the type of parent fullerene.

  8. Simulation studies on back bombardment of electrons in rf thermionic guns

    NASA Astrophysics Data System (ADS)

    Liu, Hongxiu

    1991-05-01

    Using SUPERFISH and PARMELA, we simulate the back bombardment dynamics of electrons in rf thermionic guns. First, we shed light on some basic physical pictures of the back bombardment by means of the simulation results. Then the solution to this problem is investigated through applying a transverse magnetic field vertically traversing the cathode cavity. The Glaser profile is assumed for the magnetic field. It shows that for the total emitted charge of 1.65 nC and the rf duty factor of 2.5×10 -5 the average back bombardment power can be reduced from more than 10 W to about 2 W with the varying magnetic field up to 150 G. The influence of the magnetic field on the normal electrons out of the gun cavity is examined. The correction to this influence is investigated. Some conclusions are drawn finally.

  9. ION TRAPPING AND CATHODE BOMBARDMENT BY TRAPPED IONS IN DC PHOTOGUNS.

    SciTech Connect

    POZDEYEV,E.

    2007-06-25

    DC photoguns are used to produce high-quality, high-intensity electron beams for accelerator driven applications. Ion bombardment is believed to be the major cause of degradation of the photocathode efficiency. Additionally to ions produced in the accelerating cathode-anode gap, the electron beam can ionize the residual gas in the transport line. These ions are trapped transversely within the beam and can drift back to the accelerating gap and contribute to the bombardment rate of the cathode. This paper proposes a method to reduce the flow of ions produced in the beam transport line and drifting back to the cathode-anode gap by introducing a positive potential barrier that repels the trapped ions. The reduced ion bombardment rate and increased life time of photocathodes will reduce the downtime required to service photoinjectors and associated costs.

  10. Quantitative Analysis of Fullerene Nanomaterials in Environmental Systems: A Critical Review

    PubMed Central

    Isaacson, Carl W.; Kleber, Markus; Field, Jennifer A.

    2009-01-01

    The increasing production and use of fullerene nanomaterials has led to calls for more information regarding the potential impacts that releases of these materials may have on human and environmental health. Fullerene nanomaterials, which are comprised of both fullerenes and surface-functionalized fullerenes, are used in electronic, optic, medical and cosmetic applications. Measuring fullerene nanomaterial concentrations in natural environments is difficult because they exhibit a duality of physical and chemical characteristics as they transition from hydrophobic to polar forms upon exposure to water. In aqueous environments, this is expressed as their tendency to initially (i) self assemble into aggregates of appreciable size and hydrophobicity, and subsequently (ii) interact with the surrounding water molecules and other chemical constituents in natural environments thereby acquiring negative surface charge. Fullerene nanomaterials may therefore deceive the application of any single analytical method that is applied with the assumption that fullerenes have but one defining characteristic (e.g., hydrophobicity). [1] We find that analytical procedures are needed to account for the potentially transitory nature of fullerenes in natural environments through the use of approaches that provide chemically-explicit information including molecular weight and the number and identity of surface functional groups. [2] We suggest that sensitive and mass-selective detection, such as that offered by mass spectrometry when combined with optimized extraction procedures, offers the greatest potential to achieve this goal. [3] With this review, we show that significant improvements in analytical rigor would result from an increased availability of well characterized authentic standards, reference materials, and isotopically-labeled internal standards. Finally, the benefits of quantitative and validated analytical methods for advancing the knowledge on fullerene occurrence, fate, and behavior are indicated. PMID:19764203

  11. Inhibition of nitric oxide synthase isoforms by tris-malonyl-C(60)-fullerene adducts.

    PubMed

    Wolff, D J; Papoiu, A D; Mialkowski, K; Richardson, C F; Schuster, D I; Wilson, S R

    2000-06-15

    C(3)-tris-malonyl-C(60)-fullerene and D(3)-tris-malonyl-C(60)-fullerene derivatives inhibit citrulline and NO formation by all three nitric oxide synthase isoforms in a manner fully reversible by dilution. The inhibition of citrulline formation by C(3)-tris-malonyl-C(60)-fullerene occurs with IC(50) values of 24, 17, and 123 microM for the neuronal, endothelial, and inducible nitric oxide synthase (NOS) isoforms, respectively. As measured at 100 microM l-arginine, neuronal NOS-catalyzed nitric oxide formation was inhibited 50% at a concentration of 25 microM C(3)-tris-malonyl-C(60)-fullerene. This inhibition was a multisite, positively cooperative inhibition with a Hill coefficient of 2.0. C(3)-tris-malonyl-C(60)-fullerene inhibited the arginine-independent NADPH-oxidase activity of nNOS with an IC(50) value of 22 microM but had no effects on its cytochrome c reductase activity at concentrations as high as 300 microM. The inhibition of nNOS activity by C(3)-tris-malonyl-C(60)-fullerene reduced the maximal velocity of product formation but did not alter the EC(50) value for activation by calmodulin. C(3)-tris-malonyl-C(60)-fullerene reduced the maximal velocity of citrulline formation by inducible NOS without altering the K(m) for l-arginine substrate or the EC(50) value for tetrahydrobiopterin cofactor. As measured by sucrose density gradient centrifugation, fully inhibitory concentrations of C(3)-tris-malonyl-C(60)-fullerene did not produce a dissociation of nNOS dimers into monomers. These observations are consistent with the proposal that C(3)-tris-malonyl-C(60)-fullerene inhibits the inter-subunit transfer of electrons, presumably by a reversible distortion of the dimer interface. PMID:10860539

  12. Ion bombardment effects on the fatigue life of stainless steel under simulated fusion first wall conditions

    SciTech Connect

    Kohse, G.; Harling, O.K.

    1983-01-01

    Pressurized tube specimens have been exposed to simultaneous multi-energy surface ion bombardment, fast neutron irradiation and stress and temperature cycling, in a simulation of a possible fusion reactor first wall environment. After ion bombardments equivalent to months-years of reactor operation and up to 30,000 cycles, no detrimental effects on post-irradiation fatigue life were found. The ion damage is found to enhance surface cracking, but this effect is limited to the several micron surface layer in which the ions are implanted.

  13. Environment with reduced ion bombardment energy for levitated particles in an rf plasma

    NASA Astrophysics Data System (ADS)

    Shimizu, S.; Annaratone, B. M.; Shimizu, T.; Jacob, W.; Thomas, H.; Morfill, G. E.

    2008-08-01

    We describe levitation of diamond fine particles in an H2 rf plasma chamber equipped with an adaptive rf electrode. Since suppression of ion bombardment is essential for crystalline diamond growth, we use an adaptive rf electrode system in a parallel-plate capacitively coupled rf plasma in order to levitate particles in a quasineutral 'spot plasma' region. Here the ions' energy corresponds only to the floating potential of the particles without the additional energy of the streaming ions as in the sheath. One can expect ion bombardment with considerably reduced ion energy when this technique is applied to diamond deposition on levitated particles.

  14. First-principles calculations on the structural evolution of solid fullerene-like CP x

    NASA Astrophysics Data System (ADS)

    Gueorguiev, G. K.; Furlan, A.; Hgberg, H.; Stafstrm, S.; Hultman, L.

    2006-08-01

    The formation and structural evolution of fullerene-like (FL) carbon phosphide (CP x) during synthetic growth were studied by first-principles calculations. Geometry optimizations and comparison between the cohesive energies suggest stability for solid FL-CP x compounds. In comparison with fullerene-like carbon nitride, higher curvature of the graphene sheets and higher density of cross-linkages between them is predicted and explained by the different electronic properties of P and N. Cage-like and onion-like structures, both containing tetragons, are found to be typical for fullerene-like CP x. Segregation of P is predicted at fractions exceeding 20 at.%.

  15. Energy spectrum and spectrum of optical absorption of endohedral fullerene Ca@C72

    NASA Astrophysics Data System (ADS)

    Murzashev, A. I.; Nazarova, T. E.

    2014-07-01

    The energy spectrum of the fullerene C72 has been calculated in terms of the Shubin-Vonsovskii-Hubbard model. Based on this spectrum, the spectrum of the optical absorption of the endohedral fullerene Ca@C72 has been calculated. The spectrum of the optical absorption agrees well with the experimental data. This suggests that all absorption bands in the range of 0-3 eV in endohedral fullerene can be explained by the purely electronic transitions in the subsystem of π electrons.

  16. On the interactions of the high energy photoelectrons with the fullerene shell

    NASA Astrophysics Data System (ADS)

    Drukarev, E. G.; Amusia, M. Ya.

    2013-12-01

    The probability that photoionization of the caged atom in an endohedral system is accompanied by excitation of the fullerene shell is shown to be close to unity in broad intervals of the photoelectron energies. This is obtained by summation of the perturbative series for the interaction between the photoelectron and the fullerene shell. The result can be verified in experiments. As an outcome, interaction between the photoelectron ejected from the caged atom and the fullerene shell cannot be described by a static potential, since inelastic processes become decisively important.

  17. Modeling Charge Transfer in Fullerene Collisions via Real-Time Electron Dynamics.

    PubMed

    Jakowski, Jacek; Irle, Stephan; Sumpter, Bobby G; Morokuma, Keiji

    2012-06-01

    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. PMID:26285634

  18. Optical signal demultiplexing and conversion in the fullerene-oligothiophene-CdS system

    NASA Astrophysics Data System (ADS)

    Lewandowska, Kornelia; Podborska, Agnieszka; Kwolek, Przemysław; Kim, Tae-Dong; Lee, Kwang-Sup; Szaciłowski, Konrad

    2014-11-01

    We report the photoelectrochemical photocurrent switching (PEPS) effect in the system based on a C60 derivatives and nanostructured cadmium sulfide. Rapid and efficient photocurrent switching upon changes of the electrode potential was observed. This process relies on the photocurrent generation by semiconducting particles and interfacial electron transfer reactions governed by the redox chemistry of fullerene derivatives (fullerene-oligothiophene dyads) with molecular oxygen as a final electron acceptor. Surprisingly, fullerene derivatives without thiophene moieties were much less efficient as CdS modifiers. These peculiar photoelectrochemical properties were applied for construction of an optoelectronic logic device.

  19. Higher-Order Harmonic Generation from Fullerene by Means of the Plasma Harmonic Method

    SciTech Connect

    Ganeev, R. A.; Bom, L. B. Elouga; Abdul-Hadi, J.; Ozaki, T.; Wong, M. C. H.; Brichta, J. P.; Bhardwaj, V. R.

    2009-01-09

    We demonstrate, for the first time, high-order harmonic generation from C{sub 60} by an intense femtosecond Ti:sapphire laser. Laser-produced plasmas from C{sub 60}-rich epoxy and C{sub 60} films were used as the nonlinear media. Harmonics up to the 19th order were observed. The harmonic yield from fullerene-rich plasma is about 25 times larger compared with those produced from a bulk carbon target. Structural studies of plasma debris confirm the presence and integrity of fullerenes within the plasma plume, indicating fullerenes as the source of high-order harmonics.

  20. 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

  1. Protein-directed self-assembly of a fullerene crystal

    PubMed Central

    Kim, Kook-Han; Ko, Dong-Kyun; Kim, Yong-Tae; Kim, Nam Hyeong; Paul, Jaydeep; Zhang, Shao-Qing; Murray, Christopher B.; Acharya, Rudresh; DeGrado, William F.; Kim, Yong Ho; Grigoryan, Gevorg

    2016-01-01

    Learning to engineer self-assembly would enable the precise organization of molecules by design to create matter with tailored properties. Here we demonstrate that proteins can direct the self-assembly of buckminsterfullerene (C60) into ordered superstructures. A previously engineered tetrameric helical bundle binds C60 in solution, rendering it water soluble. Two tetramers associate with one C60, promoting further organization revealed in a 1.67-Å crystal structure. Fullerene groups occupy periodic lattice sites, sandwiched between two Tyr residues from adjacent tetramers. Strikingly, the assembly exhibits high charge conductance, whereas both the protein-alone crystal and amorphous C60 are electrically insulating. The affinity of C60 for its crystal-binding site is estimated to be in the nanomolar range, with lattices of known protein crystals geometrically compatible with incorporating the motif. Taken together, these findings suggest a new means of organizing fullerene molecules into a rich variety of lattices to generate new properties by design. PMID:27113637

  2. Binding of fullerenes and nanotubes to MscL.

    PubMed

    Hilder, Tamsyn A; Ridone, Pietro; Nakayama, Yoshitaka; Martinac, Boris; Chung, Shin-Ho

    2014-01-01

    Multi-drug resistance is becoming an increasing problem in the treatment of bacterial infections and diseases. The mechanosensitive channel of large conductance (MscL) is highly conserved among prokaryotes. Evidence suggests that a pharmacological agent that can affect the gating of, or block the current through, MscL has significant potential as a new class of antimicrobial compound capable of targeting a range of pathogenic bacteria with minimal side-effects to infected patients. Using molecular dynamics we examine the binding of fullerenes and nanotubes to MscL and demonstrate that both are stable within the MscL pore. We predict that fullerenes will attenuate the flow of ions through MscL by reducing the pore volume available to water and ions, but nanotubes will prevent pore closure resulting in a permanently open pore. Moreover, we confirm experimentally that it is possible to attenuate the flow of ions through MscL using a C60-γ cyclodextrin complex. PMID:25030051

  3. Quantum-cellular-automata quantum computing with endohedral fullerenes

    SciTech Connect

    Twamley, J.

    2003-05-01

    We present a scheme to perform universal quantum computation using global addressing techniques as applied to a physical system of endohedrally doped fullerenes. The system consists of an ABAB linear array of group-V endohedrally doped fullerenes. Each molecule spin site consists of a nuclear spin coupled via a hyperfine interaction to an electron spin. The electron spin of each molecule is in a quartet ground state S=3/2. Neighboring molecular electron spins are coupled via a magnetic dipole interaction. We find that an all-electron construction of a quantum cellular automaton is frustrated due to the degeneracy of the electronic transitions. However, we can construct a quantum-cellular-automata quantum computing architecture using these molecules by encoding the quantum information on the nuclear spins while using the electron spins as a local bus. We deduce the NMR and ESR pulses required to execute the basic cellular automaton operation and obtain a rough figure of merit for the number of gate operations per decoherence time. We find that this figure of merit compares well with other physical quantum computer proposals. We argue that the proposed architecture meets well the first four DiVincenzo criteria and we outline various routes toward meeting the fifth criterion: qubit readout.

  4. Selecting boron fullerenes by cage-doping mechanisms

    NASA Astrophysics Data System (ADS)

    Boulanger, Paul; Morinière, Maxime; Genovese, Luigi; Pochet, Pascal

    2013-05-01

    So far, no boron fullerenes were synthesized: more compact sp3-bonded clusters are energetically preferred. To circumvent this, metallic clusters have been suggested by Pochet et al. [Phys. Rev. B 83, 081403(R) (2011), 10.1103/PhysRevB.83.081403] as "seeds" for a possible synthesis which would topologically protect the sp2 sector of the configuration space. In this paper, we identify a basic pentagonal unit which allows a balance between the release of strain and the self-doping rule. We formulate a guiding principle for the stability of boron fullerenes, which takes the form of an isolated filled pentagon rule (IFPR). The role of metallic clusters is then reexamined. It is shown that the interplay of the IFPR and the seed-induced doping breaks polymorphism and its related problems: it can effectively select between different isomers and reduce the reactivity of the boron shells. The balance between self and exterior doping represents the best strategy for boron buckyball synthesis.

  5. Binding of fullerenes and nanotubes to MscL

    PubMed Central

    Hilder, Tamsyn A.; Ridone, Pietro; Nakayama, Yoshitaka; Martinac, Boris; Chung, Shin-Ho

    2014-01-01

    Multi-drug resistance is becoming an increasing problem in the treatment of bacterial infections and diseases. The mechanosensitive channel of large conductance (MscL) is highly conserved among prokaryotes. Evidence suggests that a pharmacological agent that can affect the gating of, or block the current through, MscL has significant potential as a new class of antimicrobial compound capable of targeting a range of pathogenic bacteria with minimal side-effects to infected patients. Using molecular dynamics we examine the binding of fullerenes and nanotubes to MscL and demonstrate that both are stable within the MscL pore. We predict that fullerenes will attenuate the flow of ions through MscL by reducing the pore volume available to water and ions, but nanotubes will prevent pore closure resulting in a permanently open pore. Moreover, we confirm experimentally that it is possible to attenuate the flow of ions through MscL using a C60-γ cyclodextrin complex. PMID:25030051

  6. Protein-directed self-assembly of a fullerene crystal.

    PubMed

    Kim, Kook-Han; Ko, Dong-Kyun; Kim, Yong-Tae; Kim, Nam Hyeong; Paul, Jaydeep; Zhang, Shao-Qing; Murray, Christopher B; Acharya, Rudresh; DeGrado, William F; Kim, Yong Ho; Grigoryan, Gevorg

    2016-01-01

    Learning to engineer self-assembly would enable the precise organization of molecules by design to create matter with tailored properties. Here we demonstrate that proteins can direct the self-assembly of buckminsterfullerene (C60) into ordered superstructures. A previously engineered tetrameric helical bundle binds C60 in solution, rendering it water soluble. Two tetramers associate with one C60, promoting further organization revealed in a 1.67-Å crystal structure. Fullerene groups occupy periodic lattice sites, sandwiched between two Tyr residues from adjacent tetramers. Strikingly, the assembly exhibits high charge conductance, whereas both the protein-alone crystal and amorphous C60 are electrically insulating. The affinity of C60 for its crystal-binding site is estimated to be in the nanomolar range, with lattices of known protein crystals geometrically compatible with incorporating the motif. Taken together, these findings suggest a new means of organizing fullerene molecules into a rich variety of lattices to generate new properties by design. PMID:27113637

  7. Tuning of electronic properties of fullerene-oligothiophene layers

    SciTech Connect

    Lewandowska, Kornelia; Pilarczyk, Kacper E-mail: szacilow@agh.edu.pl; Podborska, Agnieszka; Kim, Tae-Dong; Lee, Kwang-Sup; Szaciłowski, Konrad E-mail: szacilow@agh.edu.pl

    2015-01-26

    Electronic properties of fullerene derivatives containing oligothiophene pendant chain (1–3 thiophene moieties) were investigated using the Kelvin probe technique and quantum chemistry methods. For electrochemical examination of these systems, Langmuir–Blodgett (LB) layers were prepared by the deposition on a gold substrate. The analysis of the experimental data shows that the value of the work function depends strongly on the length of oligothiophene chain. Similar dependence was also found for the surface photovoltage measurements conducted for the layers consisting of multiple LB films of the examined compounds deposited on gold surfaces. The assumption has been made that these changes are associated with the influence of oligothiophene chain on the electrostatic potential distribution near the surface of the sample. The hypothesis was confirmed by the results of DFT calculations, which revealed that the value of Fermi level energy shifts in the opposite direction to the determined work function. The key highlights of this study are as follows: electronic structure tuning by oligothiophene side chain; DFT calculation on fullerene-thiophene system; work function measurements of thin molecular layers.

  8. Vibrational spectroscopic and structural investigations on fullerene: A DFT approach

    NASA Astrophysics Data System (ADS)

    Christy, P. Anto; Premkumar, S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-01

    The molecular structure of fullerene (C60) molecule was optimized by the DFT/B3LYP method with 6-31G and 6-31G(d,p) basis sets using Gaussian 09 program. The vibrational frequencies were calculated for the optimized molecular structure of the molecule. The calculated vibrational frequencies confirm that the molecular structure of the molecule was located at the minimum energy potential energy surface. The calculated vibrational frequencies were assigned on the basis of functional group analysis and also confirmed using the GaussView 05 software. The frontier molecular orbitals analysis was carried out. The FMOs related molecular properties were predicted. The higher ionization potential, higher electron affinity, higher softness, lower band gap energy and lower hardness values were obtained, which confirm that the fullerene molecule has a higher molecular reactivity. The Mulliken atomic charge distribution of the molecule was also calculated. Hence, these results play an important role due to its potential applications as drug delivery devices.

  9. Fullerene-based inhibitors of HIV-1 protease.

    PubMed

    Strom, T Amanda; Durdagi, Serdar; Ersoz, Suha Salih; Salmas, Ramin Ekhteiari; Supuran, Claudiu T; Barron, Andrew R

    2015-12-01

    A series of Fmoc-Phe(4-aza-C60 )-OH of fullerene amino acid derived peptides have been prepared by solid phase peptide synthesis, in which the terminal amino acid, Phe(4-aza-C60 )-OH, is derived from the dipolar addition to C60 of the Fmoc-Nα-protected azido amino acids derived from phenylalanine: Fmoc-Phe(4-aza-C60 )-Lys3 -OH (1), Fmoc-Phe(4-aza-C60 )-Pro-Hyp-Lys-OH (2), and Fmoc-Phe(4-aza-C60 )-Hyp-Hyp-Lys-OH (3). The inhibition constant of our fullerene aspartic protease PRIs utilized FRET-based assay to evaluate the enzyme kinetics of HIV-1 PR at various concentrations of inhibitors. Simulation of the docking of the peptide Fmoc-Phe-Pro-Hyp-Lys-OH overestimated the inhibition, while the amino acid PRIs were well estimated. The experimental results show that C60 -based amino acids are a good base structure in the design of protease inhibitors and that their inhibition can be improved upon by the addition of designer peptide sequences. Copyright © 2015 European Peptide Society and John Wiley & Sons, Ltd. PMID:26767741

  10. Fullerene nanowires as a versatile platform for organic electronics

    PubMed Central

    Maeyoshi, Yuta; Saeki, Akinori; Suwa, Shotaro; Omichi, Masaaki; Marui, Hiromi; Asano, Atsushi; Tsukuda, Satoshi; Sugimoto, Masaki; Kishimura, Akihiro; Kataoka, Kazunori; Seki, Shu

    2012-01-01

    The development of organic semiconducting nanowires that act as charge carrier transport pathways in flexible and lightweight nanoelectronics is a major scientific challenge. We report on the fabrication of fullerene nanowires that is universally applicable to its derivatives (pristine C60, methanofullerenes of C61 and C71, and indene C60 bis-adduct), realized by the single particle nanofabrication technique (SPNT). Nanowires with radii of 8–11 nm were formed via a chain polymerization reaction induced by a high-energy ion beam. Fabrication of a poly(3-hexylthiophene) (P3HT): [6,6]-phenyl C61 butyric acid methyl ester (PC61BM) bulk heterojunction organic photovoltaic cell including PC61BM nanowires with precisely-controlled length and density demonstrates how application of this methodology can improve the power conversion efficiency of these inverted cells. The proposed technique provides a versatile platform for the fabrication of continuous and uniform n-type fullerene nanowires towards a wide range of organic electronics applications. PMID:22934128

  11. Binding of fullerenes and nanotubes to MscL

    NASA Astrophysics Data System (ADS)

    Hilder, Tamsyn A.; Ridone, Pietro; Nakayama, Yoshitaka; Martinac, Boris; Chung, Shin-Ho

    2014-07-01

    Multi-drug resistance is becoming an increasing problem in the treatment of bacterial infections and diseases. The mechanosensitive channel of large conductance (MscL) is highly conserved among prokaryotes. Evidence suggests that a pharmacological agent that can affect the gating of, or block the current through, MscL has significant potential as a new class of antimicrobial compound capable of targeting a range of pathogenic bacteria with minimal side-effects to infected patients. Using molecular dynamics we examine the binding of fullerenes and nanotubes to MscL and demonstrate that both are stable within the MscL pore. We predict that fullerenes will attenuate the flow of ions through MscL by reducing the pore volume available to water and ions, but nanotubes will prevent pore closure resulting in a permanently open pore. Moreover, we confirm experimentally that it is possible to attenuate the flow of ions through MscL using a C60-γ cyclodextrin complex.

  12. Baryon Budget in 2keV Galaxy Groups

    NASA Astrophysics Data System (ADS)

    Hornstrup, A.; Vikhlinin, A.; Burenin, R.; Ebeling, H.; Kotov, O.; Pedersen, K.; Quintana, H.; Rasmussen, J.

    We present gas-, total- and galaxy mass profiles from a 2 keV group of galaxies as part of measurements of these quantities from a small series of lowmass clusters and groups, drawn from a new 400 deg2 X-ray serendipitous survey of Clusters of Galaxies. The aim is to establish robust determinations of the baryon contents in these low-mass systems, and to determine if there is a baryon deficit compared to CMB observations.

  13. Proximity functions for electrons up to 10 keV

    SciTech Connect

    Chmelevsky, D.; Kellerer, A.M.; Terrissol, M.; Patau, J.P.

    1980-11-01

    Proximity functions for electrons up to 10 keV in water are computed from simulated particle tracks. Numerical results are given for the differential functions t(x) and the integral functions T(x). Basic characteristics of these functions and their connections to other microdosimetric quantities are considered. As an example of the applicability of the proximity functions, the quantity y/sub D/ for spheres is derived from t(x).

  14. Enhanced bioactivity of polyvinylidene chloride films using argon ion bombardment for guided bone regeneration.

    PubMed

    Kobayashi, Shuichiro; Hayashi, Tatsuhide; Asakura, Masaki; Hamajima, Soichiro; Sato, Yamato; Sasaki, Keisuke; Okabe, Eijiro; Kawase, Mayu; Ando, Masahiko; Kawai, Tatsushi; Noguchi, Toshihide

    2014-09-01

    Polyvinylidene chloride (PVDC) is a long chain carbon synthetic polymer. The objective of this study was to improve the bioactivity of PVDC films through surface modification using argon (Ar) ion bombardment to create Ar-modified PVDC films (Ar-PVDC) to address the clinical problems of guided bone regeneration (GBR), which is technique-sensitive, and low bone regenerative ability. First, the effects of Ar ion bombardment, a low temperature plasma etching technique widely used in industry, on PVDC film wettability, surface chemistry, and morphology were confirmed. Next, fibroblast-like and osteoblast-like cell attachment and proliferation on Ar-PVDC were assessed. As a preclinical in vivo study, Ar-PVDC was used to cover a critical-sized bone defect on rat calvaria and osteoconductivity was evaluated by micro-computed tomography analysis and histological examinations. We found that the contact angle of PVDC film decreased by 50° because of the production of -OH groups on the PVDC film surface, though surface morphological was unchanged at 30 min after Ar ion bombardment. We demonstrated that cell attachment increased by about 40% and proliferation by more than 140% because of increased wettability, and 2.4 times greater bone regeneration was observed at week 3 with Ar-PVDC compared with untreated PVDC films. These results suggest that Ar ion bombardment modification of PVDC surfaces improves osteoconductivity, indicating its potential to increase bone deposition during GBR. PMID:24893861

  15. A review of electron bombardment thruster systems/spacecraft field and particle interfaces

    NASA Technical Reports Server (NTRS)

    Byers, D. C.

    1978-01-01

    Information on the field and particle interfaces of electron bombardment ion thruster systems was summarized. Major areas discussed were the nonpropellant particles, neutral propellant, ion beam, low energy plasma, and fields. Spacecraft functions and subsystems reviewed were solar arrays, thermal control systems, optical sensors, communications, science, structures and materials, and potential control.

  16. Bombardment of gas molecules on single graphene layer at high temperature

    SciTech Connect

    Murugesan, Ramki; Park, Jae Hyun; Ha, Dong Sung

    2014-12-09

    Graphite is widely used as a material for rocket-nozzle inserts due to its excellent thermo-physical properties as well as low density. During the operation of rockets, the surface of the graphite nozzle is subjected to very high heat fluxes and the undesirable erosion of the surface occurs due to the bombardment of gas molecules with high kinetic energy, which causes a significant reduction of nozzle performance. However, the understanding and quantification of such bombardment is not satisfactory due to its complexity: The bond breaking-forming happens simultaneously for the carbon atoms of graphene, some gas molecules penetrate through the surface, some of them are reflected from the surface, etc. In the present study, we perform extensive molecular dynamics (MD) simulations to examine the bombardment phenomena in high temperature environment (several thousand Kelvin). Advanced from the previous studies that have focused on the bombardment by light molecules (e.g., H{sub 2}), we will concentrate on the impact by realistic molecules (e.g., CO{sub 2} and H{sub 2}O). LAMMPS is employed for the MD simulations with NVE ensemble and AIREBO potential for graphene. The molecular understanding of the interaction between graphene and highly energetic gas molecules will enable us to design an efficient thermo-mechanical protection system.

  17. Photon Counting Imaging with an Electron-Bombarded Pixel Image Sensor.

    PubMed

    Hirvonen, Liisa M; Suhling, Klaus

    2016-01-01

    Electron-bombarded pixel image sensors, where a single photoelectron is accelerated directly into a CCD or CMOS sensor, allow wide-field imaging at extremely low light levels as they are sensitive enough to detect single photons. This technology allows the detection of up to hundreds or thousands of photon events per frame, depending on the sensor size, and photon event centroiding can be employed to recover resolution lost in the detection process. Unlike photon events from electron-multiplying sensors, the photon events from electron-bombarded sensors have a narrow, acceleration-voltage-dependent pulse height distribution. Thus a gain voltage sweep during exposure in an electron-bombarded sensor could allow photon arrival time determination from the pulse height with sub-frame exposure time resolution. We give a brief overview of our work with electron-bombarded pixel image sensor technology and recent developments in this field for single photon counting imaging, and examples of some applications. PMID:27136556

  18. Trace Elements Reveal a Possible Link Between Jack Hills Detrital Zircons and the Late Heavy Bombardment

    NASA Astrophysics Data System (ADS)

    Bell, E. A.; Harrison, T. M.

    2012-03-01

    The Jack Hills detrital zircons range in age 4.3-3.0 Ga. At ca. 3.9 Ga the record contains a population that appears to have recrystallized during a major thermal event. This may be circumstantial terrestrial evidence for the Late Heavy Bombardment.

  19. The distribution of cotransformed transgenes in particle bombardment-mediated transformed wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although particle bombardment is the predominant method of foreign DNA direct transfer, whether transgene is integrated randomly into the genome has not been determined. In this study, we identified the distribution of transgene loci in 45 transgenic wheat (Triticum aestivum L.) lines containing c...

  20. Photon Counting Imaging with an Electron-Bombarded Pixel Image Sensor

    PubMed Central

    Hirvonen, Liisa M.; Suhling, Klaus

    2016-01-01

    Electron-bombarded pixel image sensors, where a single photoelectron is accelerated directly into a CCD or CMOS sensor, allow wide-field imaging at extremely low light levels as they are sensitive enough to detect single photons. This technology allows the detection of up to hundreds or thousands of photon events per frame, depending on the sensor size, and photon event centroiding can be employed to recover resolution lost in the detection process. Unlike photon events from electron-multiplying sensors, the photon events from electron-bombarded sensors have a narrow, acceleration-voltage-dependent pulse height distribution. Thus a gain voltage sweep during exposure in an electron-bombarded sensor could allow photon arrival time determination from the pulse height with sub-frame exposure time resolution. We give a brief overview of our work with electron-bombarded pixel image sensor technology and recent developments in this field for single photon counting imaging, and examples of some applications. PMID:27136556

  1. 33 CFR 334.950 - Pacific Ocean at San Clemente Island, California; Navy shore bombardment areas.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Pacific Ocean at San Clemente... REGULATIONS § 334.950 Pacific Ocean at San Clemente Island, California; Navy shore bombardment areas. (a) The danger zones. (1) The waters of the Pacific Ocean within an area beginning at China Point...

  2. "Colour bombardment" - a human visual problem that interferes with the viewing of anaglyph stereo material.

    PubMed

    Barber, V C; Brett, D A

    1982-01-01

    One of the problems with the use of anaglyph stereo material is the human visual phenomenon called "colour bombardment". Certain individuals find it visually distressing to receive an image that is one colour in one eye, and another colour in the other eye, and nausea and/or vertigo are the results of even a brief exposure to such anaglyph material. The problem is not a stereo one, but is an example of the visual phenomenon called "binocular rivalry" ("retinal rivalry"). The incidence of colour bombardment was determined in the present study. Two hundred human subjects (100 male, 100 female) were given various tests, including exposure to red/green anaglyph stereo material. The recorded incidence of colour bombardment in this subject pool was 7.5%. In addition to those who suffered from colour bombardment, many of the other subjects saw the stereo material in more than a single colour. They found this sufficiently irritating as to predicate against the use of anaglyph stereo methods if satisfactory alternatives are available. PMID:7167763

  3. Nano-engineered materials based on fullerenes: synthesis and biomedical applications

    NASA Astrophysics Data System (ADS)

    Fierascu, Radu Claudiu; Dumitriu, Irina; Ion, Rodica Mariana; Neagu, Monica; Constantin, Carolina; Stavaru, Crina

    2010-11-01

    The nanoengineering of various materials for biomedical application has became in the last decade one of the most important research areas, due to the continuous struggle to find new and more efficient instruments for the therapy of cancer and other diseases. Attempts to obtain functionalized derivatives of fullerene seek the synthesis of watersoluble materials, in order to investigate their effects in physiological conditions. International studies on the biological properties of fullerenes and their derivatives, are now targeted towards anti-tumor effects, pharmacology and their involvement in oxidative stress. Their toxicity, demonstrated both in vitro and in vivo is important for characterization and selection of applications. Phototoxicity of some molecules of fullerenes has been identified as future therapeutic tool. The present paper describes the synthesis, characterization and some biomedical applications of some nanomaterials based on fullerenes.

  4. Complexation of higher fullerenes by calix[5]arene-based host molecules.

    PubMed

    Haino, Takeharu; Fukunaga, Chigusa; Fukazawa, Yoshimasa

    2007-01-01

    The binding abilities of calix[5]arene-based host molecules for higher fullerenes (C76, C78, and C84) were investigated in organic solvents. The binding abilities of double-calix[5]arenes to higher fullerenes are high. In particular, their association constants to C76 and C78 in toluene reached at the order of 10(5) M(-1). In contrast, the binding abilities of simple calix[5]arenes decreased as increasing the size of the fullerenes. Accordingly, linking two calix[5]arenes with the covalent bonds creates the large cavities, complementary to higher fullerenes. The structure of the host-guest complex of double-calix[5]arene and C76 was discussed. The carbons of the polar end of C76 characteristically shifted upfield more than the other carbons in the host-guest complex, indicating that these polar carbons reside most deeply inside the cavity of the calix[5]arene. PMID:17450902

  5. Gadolinium-containing endohedral fullerenes: structures and function as magnetic resonance imaging (MRI) agents.

    PubMed

    Ghiassi, Kamran B; Olmstead, Marilyn M; Balch, Alan L

    2014-05-28

    Gadolinium-containing endohedral fullerenes represent a new class of effective relaxation agents for magnetic resonance imaging (MRI). The range of different structures possible for this class of molecules and their properties as MRI agents are reviewed here. PMID:24522668

  6. Pentacene:Fullerene Multilayer-Heterojunction Organic Photovoltaic Cells Fabricated by Alternating Evaporation Method

    NASA Astrophysics Data System (ADS)

    Sakai, Jun; Taima, Tetsuya; Yamanari, Toshihiro; Yoshida, Yuji; Fujii, Akihiko; Ozaki, Masanori

    2010-03-01

    Novel small-molecule organic photovoltaic cell structures with pentacene and fullerene multilayers are reported. Pentacene is an attractive material for photovoltaic cells, but it tends to crystallize with molecular orientation during vacuum deposition. Therefore, thus far, it has been difficult to fabricate a bulk-heterojunction active layer with fullerenes by coevaporation, despite the demand for pentacene/fullerene bilayer heterojunction cells owing to their good photovoltaic performance. Here, instead of preparing an active layer by coevaporation, we prepare a pentacene and fullerene multilayer-heterojunction active layer by alternating evaporation. It was found that multilayer cells show superior photovoltaic performance to bilayer cells owing to the improvements in their exciton dissociation efficiency and charge carrier transport properties.

  7. On the Efficiency Limit of Conjugated Polymer:Fullerene-Based Bulk Heterojunction Solar Cells.

    PubMed

    Scharber, Markus C

    2016-03-01

    The power conversion efficiency potential of eight high-performance polymer-fullerene blends is investigated. All studied absorbers show the typical organic solar cell losses limiting their performance to ≈13%. PMID:26757236

  8. Fullerenes in asphaltenes and other carbonaceous materials: natural constituents or laser artifacts.

    PubMed

    Santos, Vanessa G; Fasciotti, Maíra; Pudenzi, Marcos A; Klitzke, Clécio F; Nascimento, Heliara L; Pereira, Rosana C L; Bastos, Wagner L; Eberlin, Marcos N

    2016-04-25

    The presence of fullerenes as natural constituents of carbonaceous materials or their formation as laser artifacts during laser desorption ionization (LDI) mass spectrometry (MS) analysis is reinvestigated and reviewed. The results using asphaltene samples with varying composition as well as standard polycyclic aromatic hydrocarbons (PAH) and fullerene samples as models have demonstrated that indeed Cn ring fullerenes are not natural constituents but they are formed as common and often as predominant artifacts upon laser radiation, and a series of incorrect assignments based on LDI-MS data of several carbonaceous materials seems unfortunately to have been made. When the present results are evaluated also in the light of the vast literature on LDI-MS of carbonaceous materials, the formation of fullerene artifacts seems particularly common for LDI-MS analysis of asphaltenes and other carbonaceous samples with considerably high levels of PAH and varies according to the type of laser used, and the intensity of the laser beam. PMID:26805430

  9. Density functional studies of plasmons, hybridizations and electron diffractions in carbon fullerene nanomaterials

    NASA Astrophysics Data System (ADS)

    Chakraborty, Himadri; Madjet, Lamine

    2013-03-01

    Quantized plasma waves in carbon valence electron clouds driven by photon or charged particle fields create plasmon resonances in the ionization of fullerene nanomaterials. If the materials have composite structures, like nested fullerenes (buckyonions) or fullerenes endohedrally doped by an atom (endofullerenes), then plasmonic motions dynamically hybridize, leading to spectacular effects in the emission spectra. Further, for fast ejected electrons, diffraction type modulations in the momentum space of emission intensities enrich the ionization process which offer an unusual spectroscopic route to image the charge cloud geometry. Using a time-dependent local density functional methodology, but smearing the ionic core into a jellium, we recently completed some studies of such processes for fullerene nanomaterials. Results have shown good agreements with measurements. Supported by NSF, USA

  10. INHIBITORY POTENTIAL OF POLYHYDROXYLATED FULLERENES AGAINST PROTEIN TYROSINE PHOSPHATASE 1B.

    PubMed

    Kobzar, O L; Trush, V V; Tanchuk, V Yu; Vovk, A I

    2015-01-01

    Inhibition of PTP1B by polyhydroxylated fullerenes was studied in silico and in vitro. The enzyme kinetics in the presence of polyhydroxy small gap fullerenes showed that reciprocal value of maximum velocity non-linearly increases with increasing the inhibitor concentration. Analysis of the dose-dependent curve of PTP1B inhibition suggests an apparent positive cooperativity with involvement of at least two binding sites for the hydroxylated fullerene cages. Molecular docking calculations indicated that highly hydroxylated fullerene C60 may occupy the active site and additional allosteric binding site with similar affinity. In silico analysis of a number of fullerenols with 6, 12, 18, 24, 30, and 36 hydroxyl groups showed that the inhibitory activity may depend on the degree of hydroxylation of the nanoparticles surface. These data provide some understanding of the mechanisms of inhibitory action of fullerenols on activity of protein tyrosine phosphatases. PMID:26547960

  11. Evaluation of the physi- and chemisorption of hydrogen in alkali (Na, Li) doped fullerenes

    DOE PAGESBeta

    Ward, Patrick; Teprovich, Jospeph A.; Compton, Robert; Affholter, Kathleen A; Schwartz, Viviane; Veith, Gabriel M; Zidan, Ragiay

    2015-01-01

    Alkali doped fullerenes synthesized by two different solvent assisted mixing techniques are compared for their hydrogen uptake activity. In this study we investigated the interaction of hydrogen with alkali doped fullerenes via physisorption. In addition, we present the first mass spectrometric evidence for the formation of C60H60 via chemisorption. Hydrogen physisorption isotherms up to 1 atm at temperatures ranging from 77-303 K were measured demonstrating an increase in hydrogen uptake versus pure C60 and increased isosteric heats of adsorption for the lithium doped fullerene Li12C60. However, despite these improvements the low amount of physisorbed hydrogen at 1 atm and 77more » K in these materials suggests that fullerenes do not possess enough accessible surface area to effectively store hydrogen due to their close packed crystalline nature.« less

  12. [Effect of "micronized" C60 fullerene on the microbial growth in vitro].

    PubMed

    Chiron, J P; Lamandé, J; Moussa, F; Trivin, F; Céolin, R

    2000-05-01

    The effect of C60 "micronized fullerene was tested by a manual and automatised (Analyzer Bioscreen C(R)) micromethod on the microbial growth of 22 collection strains: E. coli (5), P. aeruginosa (2), S. Typhimurium (6), S. aureus (2), L. monocytogenes (2), E. hirae (1), B. cereus (1), B. subtilis (1), B. pumilus (1) et C. albicans (1). No effect on microbial growth was observed with C60 "micronized fullerene (43.2 microg/ml) on all strains studied: no difference was found with doubling time, slope and growth rate constant. The results of cytotoxicity obtained with animal models or in vitro cultures as human monocyte, leukocyte or macrophage confirm the absence of effect of C60 fullerene at a concentration compatible with microbial or biological models. This study is included in research program headed "Therapeutics perspectives of fullerenes. PMID:10844277

  13. Evaluation of the physi- and chemisorption of hydrogen in alkali (Na, Li) doped fullerenes

    SciTech Connect

    Ward, Patrick; Teprovich, Jospeph A.; Compton, Robert; Affholter, Kathleen A; Schwartz, Viviane; Veith, Gabriel M; Zidan, Ragiay

    2015-01-01

    Alkali doped fullerenes synthesized by two different solvent assisted mixing techniques are compared for their hydrogen uptake activity. In this study we investigated the interaction of hydrogen with alkali doped fullerenes via physisorption. In addition, we present the first mass spectrometric evidence for the formation of C60H60 via chemisorption. Hydrogen physisorption isotherms up to 1 atm at temperatures ranging from 77-303 K were measured demonstrating an increase in hydrogen uptake versus pure C60 and increased isosteric heats of adsorption for the lithium doped fullerene Li12C60. However, despite these improvements the low amount of physisorbed hydrogen at 1 atm and 77 K in these materials suggests that fullerenes do not possess enough accessible surface area to effectively store hydrogen due to their close packed crystalline nature.

  14. Biological Effects in Cell Cultures of Fullerene C60: Dependence on Aggregation State

    NASA Astrophysics Data System (ADS)

    Piotrovsky, Levon B.; Eropkin, Mikhail Yu.; Eropkina, Elena M.; Dumpis, Marina A.; Kiselev, Oleg I.

    The mechanisms of biological action of various fullerene preparations - water-soluble C60/polyvinylpyrrolidone (C60/PVP) complex and solid-state pristine fullerene C60 (fullerene on the surfaces [FoS]), in cell-free system and in different cell cultures were studied. In the cell-free system the C60/PVP complex showed the pro-oxidant activity. On the other hand, FoS in the darkness proved to be antioxidant (AO) and was nontoxic for different cell lines. But under visible-light illumination cell viability dropped in time- and light-dose-dependent way. Moreover, photodynamic damage of cells of tumor origin was greater than normal. The effect of illumination was reversed by some antioxidants. Therefore, redox properties in cell-free system and biological activity of pristine fullerene in vitro, in particular, photoxicity, depend on its aggregation state.

  15. New Ti-decorated B40 fullerene as a promising hydrogen storage material

    PubMed Central

    Dong, Huilong; Hou, Tingjun; Lee, Shuit-Tong; Li, Youyong

    2015-01-01

    The newly found B40 is the first experimentally observed all-boron fullerene and has potential applications in hydrogen storage. Here we investigate the binding ability and hydrogen storage capacity of Ti-decorated B40 fullerene based on DFT calculations. Our results indicate that Ti shows excellent binding capability to B40 compared with other transition metals. The B40 fullerene coated by 6 Ti atoms (Ti6B40) can store up to 34 H2 molecules, corresponding to a maximum gravimetric density of 8.7 wt%. It takes 0.2-0.4 eV/H2 to add one H2 molecule, which assures reversible storage of H2 molecules under ambient conditions. The evaluated reversible storage capacity is 6.1 wt%. Our results demonstrate that the new Ti-decorated B40 fullerene is a promising hydrogen storage material with high capacity. PMID:25943256

  16. Photocurrent in Multilayered Assemblies of Porphyrin-Fullerene Covalent Dyads: Evidence for Channels for Charge Transport.

    PubMed

    Konev, Alexander S; Khlebnikov, Alexander F; Levin, Oleg V; Lukyanov, Daniil A; Zorin, Ivan M

    2016-04-01

    Specially designed porphyrin-fullerene dyads have been synthesized to verify literature predictions based on quantum chemistry calculations that certain porphyrin-fullerene dyads are able to self-arrange into specific structures providing channels for charge transport in a bulk mass of organic compound. According to AFM and SEM data, the newly synthesized compounds were indeed prone to some kind of self-arrangement, although to a lesser degree than was expected. A dispersion corrected DFT study of the molecular non-covalent interactions performed at the DFT-D3 (B3LYP, 6-31G*) level of theory showed that the least energy corresponded to head-to-head dimers, with close contacts of porphyrin-porphyrin and fullerene-fullerene fragments, thus providing a unit building block of the channel for charge transport. Experimental proof for the existence of channels for charge transport was obtained by observing a photocurrent in a simple photovoltaic cell. PMID:26893269

  17. Phase separation in bulk heterojunctions of semiconducting polymers and fullerenes for photovoltaics.

    PubMed

    Treat, Neil D; Chabinyc, Michael L

    2014-01-01

    Thin-film solar cells are an important source of renewable energy. The most efficient thin-film solar cells made with organic materials are blends of semiconducting polymers and fullerenes called the bulk heterojunction (BHJ). Efficient BHJs have a nanoscale phase-separated morphology that is formed during solution casting. This article reviews recent work to understand the nature of the phase-separation process resulting in the formation of the domains in polymer-fullerene BHJs. The BHJ is now viewed as a mixture of polymer-rich, fullerene-rich, and mixed polymer-fullerene domains. The formation of this structure can be understood through fundamental knowledge of polymer physics. The implications of this structure for charge transport and charge generation are given. PMID:24689796

  18. Electronic correlation effects in a fullerene molecule studied by the variational Monte Carlo method

    SciTech Connect

    Krivnov, V.Y. ); Shamovsky, I.L. Chemistry Department, University of West Indies Mona Campus, St. Andrew, Kingston 7 ); Tornau, E.E. ); Rosengren, A. )

    1994-10-15

    Electron-correlation effects in the fullerene molecule and its ions are investigated in the framework of the Hubbard model. The variational Monte Carlo method and the Gutzwiller wave function are used. Most attention is paid to the case of intermediate interactions, but also the strong coupling limit, where the Hubbard model reduces to the antiferromagnetic Heisenberg model, is considered for the fullerene molecule. In this case we obtain a very low variational ground state energy. Futher, we have calculated the main spin correlation functions in the ground state. Only short-range order is found. The pairing energy of two electrons added to a fullerene molecule or to a fullerene ion is also calculated. Contrary to the results obtained by second-order perturbation theory, pair binding is not found.

  19. Synthesis, identification, and benzene solubility of the piperidine, pyrrolidine, and morpholine derivatives of fullerene C60

    NASA Astrophysics Data System (ADS)

    Semenov, K. N.; Charykov, N. A.; Keskinov, V. A.

    2013-01-01

    Synthesis of the piperidine, pyrrolidine, and morpholine derivatives of fullerene C60 and their identification by electronic and IR spectroscopy were reported. The solubility of these derivatives in benzene at temperatures from 20 to 80°C was studied.

  20. High-capacity stationary phases containing heavy atoms for HPLC separation of fullerenes

    SciTech Connect

    Kimata, Kazuhiro |; Hirose, Tsunehisa; Moriuchi, Kouji; Hosoya, Ken; Araki, Takeo; Tanaka, Nobuo

    1995-08-01

    A high-capacity stationary phase for the separation of fullerenes was prepared by immobilizing 3-[(pentabromobenzyl)oxy]propylsilyl (PBB) groups onto silica surfaces. The stationary phase was developed by a reciprocal approach. This was possible by finding the structure of solvents that provided high solubilities as well as high eluent strength for chromatographic elution of fullerenes. The increased solubility and increased eluent strength for C{sub 60} seen with solvents containing heavy heteroatoms suggested the preferential interaction of C{sub 60} with such solvent molecules. The stationary phases containing sulfur, chlorine, or bromine in fact resulted in longer retention of fullerenes. The PBB silica showed high retentivity with excellent efficiency for fullerenes, permitting the use of solvents providing high solubilities, such as carbon disulfide and 1,2,4-trichlorobenzene for gramscale separations with ordinary HPLC equipment. 22 refs., 6 figs., 3 tabs.