Science.gov

Sample records for 30-mev c60 clusters

  1. Light-Initiated Transformation of C60 Clusters in Water

    EPA Science Inventory

    Although Buckminster fullerene (C60) has an extremely low water solubility (~8 ng/L), the formation of stable clusters (aqu/nC60) not only greatly increases the mass of C60 dispersed in water, but also alters its physicochemical properties. This research focused on investigating ...

  2. Stability of water-stable C60 clusters to OH radical oxidation and hydrated electron reduction.

    PubMed

    Lee, Jaesang; Song, Weihua; Jang, Seung S; Fortner, John D; Alvarez, Pedro J J; Cooper, William J; Kim, Jae-Hong

    2010-05-15

    Reactions of water-stable C(60) clusters (nC(60)) in water with OH radicals (*OH) and hydrated electrons (e(aq)(-)), generated by steady-state gamma-radiation, were observed and characterized. Ordered C(60) clusters were relatively recalcitrant to highly reactive *OH and e(aq)(-) species, with only a fraction of carbons oxidized and reduced, respectively. Pulse radiolysis suggested that the reactions of nC(60) with OH* and e(aq)(-) were diffusion limited, with rate constants of (7.34 +/- 0.31) x 10(9) M(-1) s(-1) and (2.34 +/- 0.02) x 10(10) M(-1) s(-1), respectively. Quantum mechanical calculations of binding energy of the C(60)-OH adduct as a function of C(60) clustering degree indicate, despite an initial fast reaction, a slower overall conversion due to thermodynamic instability of C(60)-OH intermediates. The results imply that ordered clustering of C(60) in the aqueous phase significantly hinders C(60)'s fundamental reactivity with radical species. PMID:20397700

  3. Electronic structure of pure and K-doped C 60 clusters

    NASA Astrophysics Data System (ADS)

    Guo, J.; Ellis, D. E.; Lam, D. J.

    1991-10-01

    The electronic structure of a C 60 cluster, the soccer ball-shaped structure determined from the recent X-ray study by Hawkins et al., and of its endohedral complex KC 60 were calculated using the self-consistent-field discrete variational (DV) method in the local density theoretical framework. The calculated C 60 cluster energy levels were found in excellent agreement with the recent X-ray photoemission spectra (XPS) of Weaver et al. The ionization potential and electron affinity calculated using the transition state method are in good agreement with the experimental data. It was found that electronic structure of the endohedral complex KC 60 cluster is the same as the C 60 except that K donates one electron into the lowest unoccupied molecular orbital of C 60. The electronic charge density of C 60 was found to lie within a spherical shell of ≈8.0 au thickness surrounding the C nuclei. A cage of ≈2.0 au radius at the center of the C 60 cluster was found nearly free of electrons ( p≪ 10 -3e/ a30). The 29 eV plasma energy loss calculated approximately from the dielectric function of C 60 explains the broad satellite feature seen ≈28 eV to the higher energy side from the C 1s core line in the XPS experiment.

  4. Advanced carbon-based material C60 modification using partially ionized cluster and energetic beams

    NASA Astrophysics Data System (ADS)

    Yuancheng, Du; Zhongmin, Ren; Zhifeng, Ying; Ning, Xu; Fuming, Li

    1997-06-01

    Two processes have been undertaken using Partially ionized cluster deposition (PICBD) and energetic ion bombardment beams deposition (IBD) respectively. C60 films deposited by PICBD at V=0 and 65 V, which result in highly textured close-packed structure in orientation (110) and being more polycrystalline respectively, the resistance of C60 films to oxygen diffusion contamination will be improved. In the case of PICBD, the ionized C60 soccer-balls molecules in the evaporation beams will be fragmented in collision with the substrate under the elevated accelerating fields Va. As a new synthetic IBD processing, two low energy (400 and 1000 eV) nitrogen ion beams have been used to bombard C60 films to synthesize the carbon nitride films.

  5. Energetics and Kinetics of Ti Clustering on Neutral and Charged C60 Surfaces

    SciTech Connect

    Yang, Shenyuan; Yoon, Mina; Wang, Enge; Zhang, Zhenyu

    2008-01-01

    Abstract: Using ab initio spin density functional theory, we investigate the energetics and kinetics of Ti clustering on both neutral and charged C60 surfaces. We compare the formation energy of twodimensional (2D) and three-dimensional (3D) TiN clusters as a function of cluster size (N 12). We find that there exists a critical cluster size (NC) of NC=5, below which 2D layer structures are preferred to 3D structures. Hole- or B-doping greatly enhance the Ti-fullerene interaction and lead to stronger dispersion of Ti atoms. Even so, for moderate charge doping (less than seven holes) the critical size of Ti atoms on neutral C60 surprisingly remains unchanged or only slightly increases to NC=6 by B-doping. However, we find that the formation of 3D clusters is hindered by a high kinetic barrier related to the 2 process of single Ti atoms climbing up a single Ti layer. This barrier is ~1eV or even 1.47 eV for Bdoped C60 surfaces which is high enough to stabilize larger 2D structures (N NC) at low temperatures. These findings open a way to produce homogenously Ti-doped fullerenes which are believed to be a very promising material for hydrogen storage.

  6. Preparation of C 60 single crystalline thin film by ionized cluster beam deposition and ion implantation into single crystalline C 60 thin film

    NASA Astrophysics Data System (ADS)

    Isoda, Satoru; Kawakubo, Hiroaki; Nishikawa, Satoshi; Wada, Osamu

    1996-05-01

    We have succeeded in preparing single crystalline C 60 thin film of a lateral extension in the order of several millimeters on mica by ionized cluster beam (ICB) deposition. During the growth process, planar dendrite-like single crystalline islands were observed by an atomic force microscope (AFM). It was concluded from reflection high-energy electron diffraction (RHEED) and transmission electron diffraction (TED) analyses that these islands grow hetero-epitaxially on mica. As the deposition process continues, the single crystalline islands coalesce and finally form a giant single crystal without grain boundaries between the former islands. This layered dendrite-like crystal growth is considered to be due to the ICB process, namely, ionizing molecules and accelerating them. Furthermore, the effect of ion (P +, B +, Ar +) implantation into C 60 thin films on the molecular structure and the conductivity has been studied under various implantation conditions. It was found from the analyses of FT-IR and Raman spectroscopies that the soccer-ball-like structure of C 60 changes into a diamond-like carbon (DLC) structure with an implantation energy higher than 40 keV, whereas the structure undergoes virtually no change with 10 keV implantation. As for conductivity changes under the lower implantation energy condition, the minimum dose of P + ions required to increase the conductivity from the non-doped value (10 12 cm -2) is 10 times lower than in the case of Ar + implantation. The conductivity change for the P + implantation could be explained satisfactorily not only by the effect of chemically-modified C 60 but also by the effect of a charge-transfer state between C 60 and implanted ions. It was concluded from these results that the conductivity of the C 60 film can be controlled over a wide range based on the carrier generation mechanism, which depends on the implantation conditions.

  7. Determination of the sputtering yield of cholesterol using Arn(+) and C60(+(+)) cluster ions.

    PubMed

    Rakowska, P D; Seah, M P; Vorng, J-L; Havelund, R; Gilmore, I S

    2016-08-01

    The sputtering yield of cholesterol films on silicon wafers is measured using Arn(+) and C60(+(+)) ions in popular energy (E) and cluster size (n) ranges. It is shown that the C60(+(+)) ions form a surface layer that stabilizes the film so that a well-behaved profile is obtained. On the other hand, the Arn(+) gas clusters leave the material very clean but, at room temperature, the layer readily restructures into molecular bilayers, so that, although a useful measure may be made of the sputtering yield, the profiles become much more complex. This restructuring does not occur at room temperature normally but results from the actions of the beams in the sputtering process for profiling in secondary ion mass spectrometry. Better profiles may be made by reducing the sample temperature to -100 °C. This is likely to be necessary for many lower molecular weight materials (below 1000 Da) to avoid the movement of molecules. Measurements for cholesterol films on 37 nm of amiodarone on silicon are even better behaved and show the same sputtering yields at room temperature as those films directly on silicon at -100 °C. The yields for both C60(+(+)) and Arn(+) fit the Universal Equation to a standard deviation of 11%. PMID:27299934

  8. N-block separable random phase approximation: dipole oscillations in sodium clusters and {C}_{60} fullerene

    NASA Astrophysics Data System (ADS)

    Palade, D. I.; Baran, V.

    2016-09-01

    We generalize the schematic model based on the Random Phase Approximation (RPA) with separable interaction, to a collection of subspaces of ph excitations which interact with different coupling constants. This ansatz notably lowers the numerical effort involved, by reducing the RPA eigenvalue problem to a finite small dimensional system of equation. We derive the associated dispersion relation and the normalization condition for the newly defined unknowns of the system. In contrast with the standard separable approach, the present formalism is able to describe more than one collective excitation even in the degenerate limit, giving also access to the nature of the resonance. The theoretical framework is tested investigating the dipolar oscillations in various neutral and singly charged sodium clusters and C 60 fullerene with results in good agreement with full RPA calculations and experimental data. It is proven that the 40 eV resonance present in photoabsorption spectra of C 60 is a localized surface plasmon.

  9. Study of Flux Ratio of C60 to Ar Cluster Ion for Hard DLC Film deposition

    SciTech Connect

    Miyauchi, K.; Toyoda, N.; Kanda, K.; Matsui, S.; Kitagawa, T.; Yamada, I.

    2003-08-26

    To study the influence of the flux ratio of C60 molecule to Ar cluster ion on (diamond like carbon) DLC film characteristics, DLC films deposited under various flux ratios were characterized with Raman spectrometry and Near Edge X-ray Absorption Fine Structure (NEXAFS). From results of these measurements, hard DLC films were deposited when the flux ratio of C60 to Ar cluster ion was between 0.7 and 4. Furthermore the DLC film with constant sp2 content was obtained in the range of the ratio from 0.7 to 4, which contents are lower values than that of conventional films such as RF plasma. DLC films deposited under the ratio from 1 to 4 had hardness from 40 to 45GPa. It was shown that DLC films with stable properties of low sp2 content and high hardness were formed even when the fluxes were varied from 1 to 4 during deposition. It was indicated that this process was useful in the view of industrial application.

  10. Calculation of the cluster size distribution functions and small-angle neutron scattering data for C60/N-methylpyrrolidone

    NASA Astrophysics Data System (ADS)

    Tropin, T. V.; Jargalan, N.; Avdeev, M. V.; Kyzyma, O. A.; Sangaa, D.; Aksenov, V. L.

    2014-01-01

    The aggregate growth in a C60/N-methylpyrrolidone (NMP) solution has been considered in the framework of the approach developed earlier for describing the cluster growth kinetics in fullerene polar solutions. The final cluster size distribution functions in model solutions have been estimated for two fullerene aggregation models including the influence of complex formation on the cluster growth using extrapolations of the characteristics of the cluster state and distribution parameters. Based on the obtained results, the model curves of small-angle neutron scattering have been calculated for a C60/NMP solution at various values of the model parameters.

  11. High-T c superconductivity in potassium-doped fullerene, K xC 60, via coupled C 60 (pπ) cluster molecular orbitals and dynamic Jahn-Teller coupling

    NASA Astrophysics Data System (ADS)

    Johnson, K. H.; McHenry, M. E.; Clougherty, D. P.

    1991-11-01

    Recently observed superconductivity at 18 K in potassium-doped fullerene, K xC 60, may be due to Cooper pairing of partially occupied icosahedral C 60 cluster t 1u (pπ) molecular orbitals, induced by cooperative dynamic Jahn-Teller coupling of these orbitals to “soft-mode” vibrations of the C 60 molecules, leading to a BCS-like mechanism. Predicted are a nonvanishing isotope effect and Tc increasing to 30 K or more with optimization of doping, and significant effects with pressure.

  12. New insight into the structure of the C60Sc20 cluster: bonding, vibrational and optical properties.

    PubMed

    Tlahuice-Flores, A

    2016-05-14

    Recently, a new stable C60Sc20 cluster has been proposed. Its structure has Th symmetry and a large HOMO-LUMO gap value. In this communication a systematic study of its bonding, IR, Raman and absorption spectra has been carried out. Its calculated absorption spectrum features four peaks located at 1.34, 1.6, 1.87 and 2.1 eV. Moreover its Raman and IR spectra are dominated by the signals of normal modes with Tu, Eg and Au irreducible representations. PMID:27105055

  13. Equation of motion coupled cluster methods for electron attachment and ionization potential in fullerenes C60 and C70

    SciTech Connect

    Bhaskaran-Nair, Kiran; Kowalski, Karol; Moreno, Juana; Jarrell, Mark; Shelton, William A.

    2014-08-21

    Discovery of fullerenes has opened a entirely new chapter in chemistry due to their wide range of properties which holds exciting applications in numerous disciplines of science. The Nobel Prize in Chemistry 1996 was awarded jointly to Robert F. Curl Jr., Sir Harold W. Kroto and Richard E. Smalley in recoginition for their discovery of this new carbon allotrope. In this letter we are reporting ionization potential and electron attachment studies on fullerenes (C60 and C70) obtained with novel parallel implementation of the EA-EOM-CCSD and IP-EOM-CCSD methods in NWChem program package.

  14. New Volleyballenes: Y20C60 and La20C60

    PubMed Central

    Wang, Jing; Liu, Ying

    2016-01-01

    Two new stable Volleyballenes, the Y20C60 and La20C60 molecular clusters, are proposed on the basis of first-principles density functional theory. In conjunction with recent findings for the scandium system, these findings establish Volleyballene M20C60 molecules as a general class of stable molecules within the fullerene family. Both Y20C60 and La20C60 molecules have Th point group symmetries and relatively large HOMO-LUMO gaps. PMID:27487765

  15. New Volleyballenes: Y20C60 and La20C60

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Liu, Ying

    2016-08-01

    Two new stable Volleyballenes, the Y20C60 and La20C60 molecular clusters, are proposed on the basis of first-principles density functional theory. In conjunction with recent findings for the scandium system, these findings establish Volleyballene M20C60 molecules as a general class of stable molecules within the fullerene family. Both Y20C60 and La20C60 molecules have Th point group symmetries and relatively large HOMO-LUMO gaps.

  16. New Volleyballenes: Y20C60 and La20C60.

    PubMed

    Wang, Jing; Liu, Ying

    2016-01-01

    Two new stable Volleyballenes, the Y20C60 and La20C60 molecular clusters, are proposed on the basis of first-principles density functional theory. In conjunction with recent findings for the scandium system, these findings establish Volleyballene M20C60 molecules as a general class of stable molecules within the fullerene family. Both Y20C60 and La20C60 molecules have Th point group symmetries and relatively large HOMO-LUMO gaps. PMID:27487765

  17. Electrostatic propulsion using C60 molecules

    NASA Technical Reports Server (NTRS)

    Leifer, Stephanie D.; Rapp, Donald; Saunders, Winston A.

    1992-01-01

    An evaluation is made of the potential benefits of C60 molecules as a basis for ion propulsion. Because C60 is storable, its use may result in a larger usable propellant fraction than previous methods of cluster ion propulsion. C60 may also relax such engineering constraints as grid spacing, which restrict the performance of noble gas ion propulsion. The behavior of C60 in a plasma discharge environment, as well as various electron impact cross sections of the molecule, will greatly afftect the feasibility of the concept.

  18. Solubility of C60 in solvent mixtures.

    PubMed

    Kulkarni, Pradnya P; Jafvert, Chad T

    2008-02-01

    The potential large-scale production of fullerene C60 and its widespread use in consumer products may translate into occupational and public exposure and in long-term environmental exposure. To assess the risk and fate of C60 in the environment, it is important to understand its solvate formation in common industrial solvents as the solvates may affect various properties of C60 including reactivity and toxicity, particularly when solvates occur in C60 clusters. In this study, the solubility measurements in mixed solvent system can provide useful information about solvate formation. The solubility of C60 was measured in pure toluene, tetrahydrofuran, ethanol, and acetonitrile to be 3000, 11, 1.4, and 0.04 mg/L, respectively. Additionally, the solubility of C60 was measured in mixtures of toluene-acetonitrile, toluene-ethanol, toluene-tetrahydrofuran, and acetonitrile-tetrahydrofuran. The solubility data were modeled with some accuracy using Wohl's equation. The estimated crystal energy term for C60 in tetrahydrofuran was different than that in the other solvents, indicating that the C60 solid phase in equilibrium with tetrahydrofuran solution may be a solvated crystal. PMID:18323111

  19. Electronic structure, conductivity and superconductivity of metal doped C60

    SciTech Connect

    Haddon, R.C.

    1993-12-31

    The curvature and topology required for fullerene formation strongly enhances the electronegativity of the carbon clusters and as a result C60 readily accepts electrons. Solid C60 undergoes doping with a variety of metals to produce intercalation compounds which are conductors. In the case of the alkali metals the predominant phases present are: C60, A3C60, and A6C60. The A3C60 compounds are formed from C60 by occupancy of the interstitial sites of the fcc lattice. These phases constitute the first 3-dimensional organic conductors and for A=K, Rb the A3C60 compounds are superconductors with transition temperatures of Tc=19 and 28K, respectively. There is evidence to suggest that the superconductivity in these systems is driven by the intramolecular vibrations of the reduced C60 molecule. Recent experiments on a variety of metal doped C60 thin films will be presented.

  20. Buckling of C60 whiskers

    NASA Astrophysics Data System (ADS)

    Asaka, Koji; Kato, Ryoei; Miyazawa, Kun'ichi; Kizuka, Tokushi

    2006-08-01

    The authors demonstrated the mechanics of materials for crystalline whiskers composed of C60 molecules; compressive deformation of the whiskers was observed by in situ transmission electron microscopy with simultaneous force measurement by means of an optical cantilever method, as used in atomic force microscopy. In response to compression along the long axis, the whiskers bent first elastically, then buckled. A whisker with 160nm diameter fractured brittlely at a strain of 0.08. According to Euler's formula, Young's modulus of the whisker was estimated to be 32-54GPa, which is 160%-650% of that of C60 bulk crystals.

  1. Sc20C60: a volleyballene

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Ma, Hong-Man; Liu, Ying

    2016-06-01

    An exceptionally stable hollow cage containing 20 scandium atoms and 60 carbon atoms has been identified. This Sc20C60 molecular cluster has a Th point group symmetry and a volleyball-like shape that we refer to below as ``Volleyballene''. Electronic structure analysis shows that the formation of delocalized π bonds between Sc atoms and the neighboring pentagonal rings made of carbon atoms is crucial for stabilizing the cage structure. A relatively large HOMO-LUMO gap (~1.4 eV) was found. The results of vibrational frequency analysis and molecular dynamics simulations both demonstrate that this Volleyballene molecule is exceptionally stable.An exceptionally stable hollow cage containing 20 scandium atoms and 60 carbon atoms has been identified. This Sc20C60 molecular cluster has a Th point group symmetry and a volleyball-like shape that we refer to below as ``Volleyballene''. Electronic structure analysis shows that the formation of delocalized π bonds between Sc atoms and the neighboring pentagonal rings made of carbon atoms is crucial for stabilizing the cage structure. A relatively large HOMO-LUMO gap (~1.4 eV) was found. The results of vibrational frequency analysis and molecular dynamics simulations both demonstrate that this Volleyballene molecule is exceptionally stable. Electronic supplementary information (ESI) available: Sc20C60: a Volleyballene_SI. See DOI: 10.1039/c5nr07784b

  2. Sc20C60: a volleyballene.

    PubMed

    Wang, Jing; Ma, Hong-Man; Liu, Ying

    2016-06-01

    An exceptionally stable hollow cage containing 20 scandium atoms and 60 carbon atoms has been identified. This Sc20C60 molecular cluster has a Th point group symmetry and a volleyball-like shape that we refer to below as "Volleyballene". Electronic structure analysis shows that the formation of delocalized π bonds between Sc atoms and the neighboring pentagonal rings made of carbon atoms is crucial for stabilizing the cage structure. A relatively large HOMO-LUMO gap (∼1.4 eV) was found. The results of vibrational frequency analysis and molecular dynamics simulations both demonstrate that this Volleyballene molecule is exceptionally stable. PMID:26878201

  3. Helium Droplets Doped with Sulfur and C60

    PubMed Central

    2014-01-01

    Clusters of sulfur are grown by passing superfluid helium nanodroplets through a pickup cell filled with sulfur vapor. In some experiments the droplets are codoped with C60. The doped droplets are collided with energetic electrons and the abundance distributions of positively and negatively charged cluster ions are recorded. We report, specifically, distributions of Sm+, Sm–, and C60Sm– containing up to 41 sulfur atoms. We also observe complexes of sulfur cluster anions with helium; distributions are presented for HenSm– with n ≤ 31 and m ≤ 3. The similarity between anionic and cationic C60Sm± spectra is in striking contrast to the large differences between spectra of Sm+ and Sm–. PMID:26045732

  4. Biological applications of hydrophilic C60 derivatives (hC60s)- a structural perspective.

    PubMed

    Zhu, Xiaolei; Sollogoub, Matthieu; Zhang, Yongmin

    2016-06-10

    Reactive oxygen species (ROS) generation and radical scavenging are dual properties of hydrophilic C60 derivatives (hC60s). hC60s eliminate radicals in dark, while they produce reactive oxygen species (ROS) in the presence of irradiation and oxygen. Compared to the pristine C60 suspension, the aqueous solution of hC60s is easier to handle in vivo. hC60s are diverse and could be placed into two general categories: covalently modified C60 derivatives and pristine C60 solubilized non-covalently by macromolecules. In order to present in detail, the above categories are broken down into 8 parts: C60(OH)n, C60 with carboxylic acid, C60 with quaternary ammonium salts, C60 with peptide, C60 containing sugar, C60 modified covalently or non-covalently solubilized by cyclodextrins (CDs), pristine C60 delivered by liposomes, functionalized C60-polymer and pristine C60 solubilized by polymer. Each hC60 shows the propensity to be ROS producer or radical scavenger. This preference is dependent on hC60s structures. For example, major application of C60(OH)n is radical scavenger, while pristine C60/γ-CD complex usually serves as ROS producer. In addition, the electron acceptability and innate hydrophobic surface confer hC60s with O2 uptake inhibition, HIV inhibition and membrane permeability. In this review, we summarize the preparation methods and biological applications of hC60s according to the structures. PMID:27049677

  5. Nanosegregation in Na2C60

    SciTech Connect

    Klupp, G.; Kamaras, K.; Matus, P.; Kiss, L.F.; Kovats, E.; Pekker, S.; Nemes, N.M.; Quintavalle, D.; Janossy, A.

    2005-09-27

    There is continuous interest in the nature of alkali metal fullerides containing C{sub 60}{sup 4-} and C{sub 60}{sup 2-}, because these compounds are believed to be nonmagnetic Mott-Jahn-Teller insulators. This idea could be verified in the case of A4C60, but Na2C60 is more controversial. By comparing the results of infrared spectroscopy and X-ray diffraction, we found that Na2C60 is segregated into 3-10 nm large regions. The two main phases of the material are insulating C60 and metallic Na3C60. We found by neutron scattering that the diffusion of sodium ions becomes faster on heating. Above 470 K Na2C60 is homogeneous and we show IR spectroscopic evidence of a Jahn-Teller distorted C{sub 60}{sup 2-} anion.

  6. Superconductivity in alkali-doped C60

    NASA Astrophysics Data System (ADS)

    Ramirez, Arthur P.

    2015-07-01

    Superconductivity in alkali-doped C60 (A3C60, A = an alkali atom) is well described by an s-wave state produced by phonon mediated pairing. Moderate coupling of electrons to high-frequency shape-changing intra-molecular vibrational modes produces transition temperatures (Tc) up to 33 K in single-phase material. The good understanding of pairing in A3C60 offers a paradigm for the development of new superconducting materials.

  7. Photoemission study of Li@C60

    NASA Astrophysics Data System (ADS)

    Yagi, Hajime; Ogasawara, Naoko; Zenki, Masashi; Miyazaki, Takafumi; Hino, Shojun

    2016-05-01

    Ultraviolet and X-ray photoelectron spectra (UPS and XPS) of thin films prepared by either depositing or applying [Li@C60]+(PF6)- on the substrates are presented. The UPS and XPS of [Li@C60]+(PF6)- applied films suggest that PF6- anions come out from the surface by annealing at 250 °C. The UPS and XPS of the deposited thin films indicate that the film does not contain PF6- anion but is composed of only Li@C60. Changing the sublimation temperature reveals that encapsulated Li cations begin to escape from the C60 cage when heated above 550 °C.

  8. Structural and electronic properties of sodium-intercalated C60

    NASA Astrophysics Data System (ADS)

    Rosseinsky, M. J.; Murphy, D. W.; Fleming, R. M.; Tycko, R.; Ramirez, A. P.; Siegrist, T.; Dabbagh, G.; Barrett, S. E.

    1992-04-01

    The synthesis and initial characterization of bulk Na(x)C60 (x = 2-6) and mixed alkali phase Na2AC60 (where A is K, Rb, or Cs) are reported. All of these phases have intercalated fcc structures. The Na6C60 structure has a Na4 cluster centered on the octahedral site. The Na2AC60 compounds superconduct for the larger A cations, but a crossover to nonsuperconducting behavior occurs with decreasing cation size and correlates with a minimum in the unit cell volume.

  9. 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

  10. Nonlinear spectroscopy of C60 single crystal

    NASA Astrophysics Data System (ADS)

    Zamboni, Roberto; Muccini, Michele; Danieli, R.; Taliani, Carlo; Mohn, H.; Muller, W.; ter Meer, Hans-Ulrich

    1994-11-01

    Two-photon excitation measurements of C60 single crystal at 4 K have been performed. The TPE spectrum shows a sharp band at 1.846 eV which is assigned to the C60 lowest forbidden Frenkel singlet exciton of T1g symmetry. This assignment is supported by the analysis of Herzberg-Teller induced photoluminescence.

  11. Electrostatic Propulsion Using C60 Molecules

    NASA Technical Reports Server (NTRS)

    Leifer, Stephanie D.; Saunders, Winston A.

    1993-01-01

    Report proposes use of C60 as propellant material in electrostatic propulsion system of spacecraft. C60, C70, and similar molecules, have recently been found to have characteristics proving advantageous in electrostatic propulsion. Report discusses these characteristics and proposes experiments to determine feasibility of concept.

  12. 15 CFR 8c.60 - Communications.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Communications. 8c.60 Section 8c.60 Commerce and Foreign Trade Office of the Secretary of Commerce ENFORCEMENT OF NONDISCRIMINATION ON THE... Communications. (a) The agency shall take appropriate steps to ensure effective communication with...

  13. 15 CFR 8c.60 - Communications.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 1 2011-01-01 2011-01-01 false Communications. 8c.60 Section 8c.60 Commerce and Foreign Trade Office of the Secretary of Commerce ENFORCEMENT OF NONDISCRIMINATION ON THE... Communications. (a) The agency shall take appropriate steps to ensure effective communication with...

  14. 15 CFR 8c.60 - Communications.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 15 Commerce and Foreign Trade 1 2013-01-01 2013-01-01 false Communications. 8c.60 Section 8c.60 Commerce and Foreign Trade Office of the Secretary of Commerce ENFORCEMENT OF NONDISCRIMINATION ON THE... Communications. (a) The agency shall take appropriate steps to ensure effective communication with...

  15. Electron transport properties and spin modulation effect analysis for C60, Au@C60 and Ag@C60

    NASA Astrophysics Data System (ADS)

    Wang, Fangyuan; Li, Guiqin

    2016-04-01

    The electron transport properties of C60, Au@C60 and Ag@C60 junctions between Au electrodes are investigated with density functional theory and the first-principle nonequilibrium Greens function. Density of states and transmission possibility as functions of energy are examined, and current-voltage characteristics of all these models are calculated with and without spin correction. With spin correction, we find a spin-current difference in Au@C60 as large as an order of magnitude. It may be used to obtain high-purity arbitrary spin current. By comparing the calculation results with and without spin correction, we attribute this spin difference to the spin resonance between transmission electrons and the valence electron of endohedral Au atom.

  16. Preparation of C60 by Detonation Technique

    NASA Astrophysics Data System (ADS)

    Wei, Xianfeng; Han, Yong; Long, Xinping

    2012-11-01

    A mixture of TNT (Trinitrotoluene) and natural graphite was detonated in a vacuum container which was immersed into cooling water; detonation products were collected for detecting. The results of mass spectroscopy, high performance liquid chromatography showed significant signals of C60, which proved that C60 could be synthesized by detonating the mixture of TNT/graphite and the detonation pressure was around 12.3 GPa and the detonation temperature was around 1985 K.

  17. Hugoniot of C60 fullerite: new results

    NASA Astrophysics Data System (ADS)

    Milyavskiy, Vladimir; Utkin, Alexander; Zhuk, Andrey; Yakushev, Vladislav; Fortov, Vladimir

    2005-07-01

    Recently, we have experimentally studied shock compressibility of C60 fullerite and sound velocity in shock-compressed fullerite at the pressure range up to ˜50 GPa [1]. In this work we present the results of new shock experiments executed with C60 fullerite in the same pressure range. On the base of new experimental results, we have made some correction of our concept [1] of the processes occurring in C60 fullerite at shock compression. In particular, the anomalous behavior of the rear surface velocity profiles was detected at pressure ˜9 GPa [1]. Additional experiments have shown that this anomalous behavior was caused by jump of the sound velocity in C60 because of formation of more hard carbon phase. We assume that it is a polymerized C60 phase. In the pressure region 9-25 GPa, destruction of this phase and formation of a graphite-like carbon occurs. With further growth of shock pressure, phase transition of the graphite-like carbon to a diamond-like phase is observed with a transition onset pressure ˜25 GPa. If shock pressures higher than ˜33 GPa, Hugoniot of C60 is determined by the thermodynamic properties of the diamond-like phase. [1] V.V. Milyavskiy, A.V. Utkin, E.B. Zaretsky, A.Z. Zhuk, V.V. Yakushev, V.E. Fortov. AIP CP 706 (2004) 667.

  18. IR absorptions of C60(+) and C60(-) in neon matrixes.

    PubMed

    Kern, Bastian; Strelnikov, Dmitry; Weis, Patrick; Böttcher, Artur; Kappes, Manfred M

    2013-08-29

    C60(+) ions were produced by electron-impact ionization of sublimed C60, collimated into an ion beam, turned 90° by an electrostatic deflector to separate them from neutrals, mass filtered by a radio frequency quadrupole, and co-deposited with Ne on a cold 5 K gold-coated sapphire substrate. Infrared absorption spectroscopy revealed the additional presence of C60 and C60(-) in the as-prepared cryogenic matrixes. To change the C60(+)/C60(-) ratio, CCl4 or CO2 electron scavengers were added to the matrix gas. Also taking into account DFT calculations, we have identified nine new previously unpublished IR absorptions of C60(+) and seven of C60(-) in Ne matrixes. Our measurements are in very good agreement with DFT calculations, predicting D5d C60(+) and D3d C60(-) ground states. The new results may be of interest regarding the presence of C60 and C70 (as well as ions thereof) in Space. PMID:23902528

  19. C60 oxide as a key component of aqueous C60 colloidal suspensions.

    PubMed

    Murdianti, Befrika S; Damron, Joshua T; Hilburn, Martha E; Maples, Randall D; Hikkaduwa Koralege, Rangika S; Kuriyavar, Satish I; Ausman, Kevin D

    2012-07-17

    Stable aqueous fullerene colloidal suspensions (nC(60)) are demonstrated to rely on the [6,6]-closed epoxide derivative of the fullerene (C(60)O) for stability. This derivative is present, though often unrecognized, in small quantities in nearly all C(60) starting materials due to a reaction with air. The low-yield formation of nC(60) from organic solvent solutions results from a preferential partitioning and thus enrichment of C(60)O in the colloidal particles. This partitioning is significantly retarded in the nC(60) synthesis method that does not involve organic solvent solutions: long-term stirring in water. Instead, this method relies on trace levels of ozone in the ambient atmosphere to produce sufficient C(60)O at the surfaces of the nC(60) particles to allow stable suspension in water. Controlled-atmosphere syntheses, deliberate C(60)O enrichment, light scattering measurements, and extraction followed by HPLC analysis and UV-visible absorption spectroscopy support the above model of nC(60) formation and stabilization. PMID:22703564

  20. 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.

  1. Sublimed C60 films for tribology

    NASA Astrophysics Data System (ADS)

    Bhushan, Bharat; Gupta, B. K.; Van Cleef, Garrett W.; Capp, Cindy; Coe, James V.

    1993-06-01

    Fullerenes take the form of hollow, geodesic domes, which are formed from a network of pentagons and hexagons. The C60 molecule has the highest possible symmetry (icosahedral) and assumes the shape of a soccer ball. At room temperature, fullerene molecules pack in a face-centered-cubic lattice bonded with weak van der Waals attractions. Fullerenes can be dissolved in solvents such as toluene and benzene and easily sublimed. The resilience, high load bearing capacity, low surface energy, high chemical stability, and spherical shape of C60 molecules and weak intermolecular bonding offer great potential for various mechanical and tribological applications. Sublimed films of C60 have been produced and friction and wear performance of these films in various operating environments are the subject of this letter.

  2. 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.

  3. Inversion Symmetry Breaking in Endohedral C_60

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis; Anderson, Frederick

    1998-03-01

    A pseudo--Jahn--Teller model describing central atom distortions is proposed for endohedral fullerenes of the form A@C_60 where A is either a rare gas or a metal atom. A critical (dimensionless) coupling gc is found, at or below which the symmetric configuration is stable and above which inversion symmetry is broken. Vibronic parameters are given for selected endohedral fullerenes.

  4. The encapsulated lithium effect on the first hyperpolarizability of C60Cl2 and C60F2.

    PubMed

    Song, Yao-Dong; Wang, Liang; Wu, Li-Ming; Chen, Qiao-Ling; Liu, Fa-Kun; Tang, Xiao-Wen

    2016-02-01

    In this paper, we report a study on the structure and first hyperpolarizability of C60Cl2 and C60F2. The calculation results show that the first hyperpolarizabilities of C60Cl2 and C60F2 were 172 au and 249 au, respectively. Compared with the fullerenes, the first hyperpolarizability of C60Cl2 increased from 0 au to 172 au, while the first hyperpolarizability of C60F2 increased from 0 au to 249 au. In order to further increase the first hyperpolarizability of C60Cl2 and C60F2, Li@C60Cl2 and Li@C60F2 were obtained by introducing a lithium atom to C60Cl2 and C60F2. The first hyperpolarizabilities of Li@C60Cl2 and Li@C60F2 were 2589 au and 985 au, representing a 15-fold and 3.9-fold increase, respectively, over those of C60Cl2 and C60F2. The transition energies of four molecules (C60Cl2, Li@C60Cl2, C60F2, Li@C60F2) were calculated, and were found to be 0.17866 au, 0.05229 au, 0.18385 au, and 0.05212 au, respectively. A two-level model explains why the first hyperpolarizability increases for Li@C60Cl2 and Li@C60F2. PMID:26841975

  5. Synthesis of C60H2 by rhodium-catalyzed hydrogenation of C60

    NASA Technical Reports Server (NTRS)

    Becker, L.; Evans, T. P.; Bada, J. L.; Miller, S. L. (Principal Investigator)

    1993-01-01

    Reduction of C60 with rhodium(0) on alumina and hydrogen in deuterated benzene (C6D6) at ambient temperature and pressure yields a mixture of hydrogenated compounds; C60H2 has been characterized as the major product in 14% yield based on 1H NMR.

  6. Charge transfer and formation of conducting C60 monolayers at C60/noble-metal interfaces

    NASA Astrophysics Data System (ADS)

    Nouchi, Ryo; Kanno, Ikuo

    2005-05-01

    The resistance of a conducting C60 monolayer formed on a polycrystalline Ag film was found to be 0.7±0.1kΩ by in situ resistance measurements. By another series of in situ resistance measurements, the surface scattering cross sections, whose magnitude represents the relative amount of transferred charge, were evaluated as 100Å2 for C60/Au, and 150Å2 for C60/Cu and C60/Ag systems. However, comparison with previous results obtained for monolayers formed on Au and Cu films showed that the resistances of conducting C60 monolayers do not show a simple dependence on the transferred charge. Atomic force microscopy measurements revealed that the grain size of the underlying noble metals also plays an important role.

  7. C_60 Nanotips for Scanning Tunneling Microscopy

    NASA Astrophysics Data System (ADS)

    Halas, N. J.

    1997-03-01

    Individual C_60 molecules are shown to provide stable conductive molecular tunneling sites, or nanotips, on the probe tip of a scanning tunneling microscope (STM). The chemisorptive attachment and subsequent imaging of discrete single molecules on an STM tip apex have been previously reported.(K. F. Kelly, D. Sarkar, S. Prato, J. S. Resh, G. D. Hale, and N. J. Halas, J. Vac. Sci. Tech. B14), 593 (1996). Functionalizing an STM tip with a C_60 molecular adsorbate alters the density of states near the Fermi energy of the tip tunneling site and modifies its imaging characteristics. These tips have permitted the observation of threefold symmetric electron scattering surrounding point defects on graphite surfaces, an effect which could not be observed using bare metal tips.(K. F. Kelly, D. Sarkar, G. D. Hale, S. J. Oldenburg, and N. J. Halas, Science 273), 1371 (1996).

  8. On the vibrational modes of C 60

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.; Gorman, John P.

    1996-03-01

    The vibrational spectrum of C 60 is compared to the spectrum of a classical isotropic elastic spherical shell. We show correlations between the low frequency modes of C 60 and those of the spherical shell. We find the spherical model gives the approximate frequency ordering for the low frequency modes. We estimate a Poisson ratio of σ ≈ 0.30 and a transverse speed of sound of υs ≈ 1800 m/s for the equivalent elastic shell. We also find that ω( M1) /ω( M0) = √ 3/2 for the shell modes M 0 and M 1, independent of elastic constants. We find that this ratio compares favorably with an experimental value of 1.17.

  9. Electronic Structure of Crystalline Buckyballs: fcc-C60

    NASA Astrophysics Data System (ADS)

    Jalali-Asadabadi, Saeid; Ghasemikhah, E.; Ouahrani, T.; Nourozi, B.; Bayat-Bayatani, M.; Javanbakht, S.; Aliabad, H. A. Rahnamaye; Ahmad, Iftikhar; Nematollahi, J.; Yazdani-Kachoei, M.

    2016-01-01

    The electronic properties of pristine fcc-C60 are calculated by utilizing a variety of density functional theory (DFT) approaches including the Perdew-Burke-Ernzerhof generalized gradient approximation (PBE-GGA), PBE-GGA+DFT-D3(vdW), Engel and Vosko GGA (EV-GGA), GGA plus Hubbard U parameter (GGA+U), hybrids Becke-Perdew-Wang hybrid functional (B3PW91), Becke-Lee-Yang-Parr hybrid functional (B3LYP), the PBE exchange-correlation functional (PBE0), and Tran and Blaha regular and non-regular modified Becke and Johnson (TB-mBJ) potential within a DFT frame work using augmented plane waves plus local orbital method. The comparison of the calculated results with the experimental values shows that the non-regular TB-mBJ method reproduces a correct experimental direct band gap of 2.12 eV at X symmetry for this compound. The effectiveness of this theoretical approach in the reproduction of the experimental band gap is due to the proper treatment of the electrons in the interstitial region of the crystal. Our results show that the C60 clusters are weakly interacting with each other in the fcc crystal. This study also reveals that the five-fold degeneracies of the isolated C60 molecule due to its icosahedral symmetry are completely lifted at an X symmetry point by the crystal field.

  10. Ferroelectricity in (K@C60)n

    NASA Astrophysics Data System (ADS)

    Clougherty, Dennis P.

    2000-09-01

    A theoretical analysis of the ground state of long-chain (K@C60)n is presented. Within mean field theory, a ferroelectric ground state is found to be stable because of the pseudo-Jahn-Teller mixing of the b1u and the b2g band with a zone-center optical phonon involving the displacement of the endohedral K- ions. A phase diagram for this model is derived in the narrow bandwidth regime.

  11. SiC formation on Si(100) via C 60 precursors

    NASA Astrophysics Data System (ADS)

    De Seta, M.; Tomozeiu, N.; Sanvitto, D.; Evangelisti, F.

    2000-07-01

    The interaction between C 60 molecules and the Si(100) surface and the preparation of silicon-carbide thin films by thermal reaction of C 60 molecules with the Si(100) surface have been investigated using X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, reflection high-energy electron diffraction and atomic force microscopy measurements. The effects of annealing temperature and C 60 coverage on the SiC formation will be discussed. It is found that the C 60 molecules bond covalently with silicon, and the number of bonds increase upon increasing the annealing temperature. Annealing at T≥830°C entails the formation of stoichiometric silicon carbide clusters that coalesce to form a continuous SiC layer when the C 60 coverage is greater than one monolayer. Deep pits acting as silicon diffusion channels are present with dimensions that increase with the amounts of C 60. The interaction of C 60 with the SiC surface was also investigated. It is found that a similar covalent interaction is present in the two systems C 60/Si and C 60/SiC.

  12. Exohedral M-C60 and M2-C60 (M = Pt, Pd) systems as tunable-gap building blocks for nanoarchitecture and nanocatalysis

    NASA Astrophysics Data System (ADS)

    Özdamar, Burak; Boero, Mauro; Massobrio, Carlo; Felder-Flesch, Delphine; Le Roux, Sébastien

    2015-09-01

    Transition metal-fullerenes complexes with metal atoms bound on the external surface of C60 are promising building blocks for next-generation fuel cells and catalysts. Yet, at variance with endohedral M@C60, they have received a limited attention. By resorting to first principles simulations, we elucidate structural and electronic properties for the Pd-C60, Pt-C60, PtPd-C60, Pd2-C60, and Pt2-C60 complexes. The most stable structures feature the metal atom located above a high electron density site, namely, the π bond between two adjacent hexagons (π-66 bond). When two metal atoms are added, the most stable configuration is those in which metal atoms still stand on π-66 bonds but tends to clusterize. The electronic structure, rationalized in terms of localized Wannier functions, provides a clear picture of the underlying interactions responsible for the stability or instability of the complexes, showing a strict relationship between structure and electronic gap.

  13. 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.

  14. Enhanced photoluminescence of C 60 incorporated into interlayers of hydrotalcite

    NASA Astrophysics Data System (ADS)

    Ding, Weiping; Gu, Gang; Zhong, Wei; Zang, Wen-Cheng; Du, Youwei

    1996-11-01

    Strong photoluminescence of sodium-reduced C 60 incorporated into interlayers of hydrotalcite is observed. This phenomenon is correlated to the fact that the reduced C 60 is positioned between positively charged layers of the anion clay. The interaction between the layers and reduced C 60 alters the photophysical properties of C 60 and relaxes the electron transition inhibition, thus enhancing photoluminescence.

  15. Identification of More Interstellar C60+ Bands

    NASA Astrophysics Data System (ADS)

    Walker, G. A. H.; Bohlender, D. A.; Maier, J. P.; Campbell, E. K.

    2015-10-01

    Based on gas-phase laboratory spectra at 6 K, Campbell et al. confirmed that the diffuse interstellar bands (DIBs) at 9632.7 and 9577.5 Å are due to absorption by the fullerene ion {{{C}}}60+. They also reported the detection of two other, weaker bands at 9428.5 and 9365.9 Å. These lie in spectral regions heavily contaminated by telluric water vapor lines. We acquired CFHT ESPaDOnS spectra of HD 183143 close to the zenith and chopped with a nearby standard to correct for the telluric line absorption which enabled us to detect a DIB at 9365.9 Å of relative width and strength comparable to the laboratory absorption. There is a DIB of similar strength and FWHM at 9362.5 Å. A stellar emission feature at 9429 Å prevented detection of the 9428.5 Å band. However, a CFHT archival spectrum of HD 169454, where emission is absent at 9429 Å, clearly shows the 9428.5 Å DIB with the expected strength and width. These results further confirm {{{C}}}60+ as a DIB carrier. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

  16. Yttrium-dispersed C60 fullerenes as high-capacity hydrogen storage medium

    NASA Astrophysics Data System (ADS)

    Tian, Zi-Ya; Dong, Shun-Le

    2014-02-01

    Interaction between hydrogen molecules and functionalized C60 is investigated using density functional theory method. Unlike transition metal atoms that tend to cluster on the surface, C60 decorated with 12 Yttrium atoms on each of its 12 pentagons is extremely stable and remarkably enhances the hydrogen adsorption capacity. Four H2 molecules can be chemisorbed on a single Y atom through well-known Dewar-Chatt-Duncanson interaction. The nature of bonding is a weak physisorption for the fifth adsorbed H2 molecule. Consequently, the C60Y12 complex with 60 hydrogen molecules has been demonstrated to lead to a hydrogen storage capacity of ˜6.30 wt. %.

  17. Geometric, electronic, and vibrational structures of C50, C60, C70, and C80

    NASA Astrophysics Data System (ADS)

    Woo, Sang Jeong; Kim, Eunja; Lee, Young Hee

    1993-03-01

    We have performed a molecular-dynamics simulation combined with the empirical tight-binding total-energy calculation method to study the carbon clusters C50, C60, C70, and C80. The optimized structure of C60, obtained by slow quenching from finite-temperature molecular dynamics, gives excellent agreement with results reported previously. The corresponding cluster structures are also determined through this calculational scheme. A systematic study of the geometric, electronic, and vibrational properties of these clusters is carried out and compared with other results.

  18. Short-pulse laser-produced plasma from C60 molecules

    SciTech Connect

    Wuelker, Cornelius; Theobald, Wolfgang; Ouw, Donald; Schaefer, Fritz P.; Chichkov, Boris N.

    1995-05-01

    The first experimental observations of a plasma produced in a vapor of C60 molecules with a high-intensity subpicosecond KrF laser (6x10{sup 15} W/cm{sup 2}) are reported. It differs from a plasma created in an ordinary carbon preplasma by reaching much higher ionization stages under the same experimental conditions. This remarkable property of C60 molecules (and other clusters) opens new prospects for short-pulse driven X-ray lasers.

  19. Alignment of paired molecules of C60 within a hexagonal platform networked through hydrogen-bonds.

    PubMed

    Hisaki, Ichiro; Nakagawa, Shoichi; Sato, Hiroyasu; Tohnai, Norimitsu

    2016-07-28

    We demonstrate, for the first time, that a hydrogen-bonded low-density organic framework can be applied as a platform to achieve periodic alignment of paired molecules of C60, which is the smallest example of a finite-numbered cluster of C60. The framework is a layered assembly of a hydrogen-bonded 2D hexagonal network (LA-H-HexNet) composed of dodecadehydrotribenzo[18]annulene derivatives. PMID:27417325

  20. Mesoscale aggregation properties of C60 in toluene and chlorobenzene.

    PubMed

    Guo, Rong-Hao; Hua, Chi-Chung; Lin, Po-Chang; Wang, Ting-Yu; Chen, Show-An

    2016-07-20

    The mesoscale aggregation properties of C60 in two distinct aromatic solvents (toluene and chlorobenzene) and a practical range of concentrations (c = 1-2 and c = 1-5 mg mL(-1), respectively) were systematically explored by static/dynamic light scattering (SLS/DLS), small angle X-ray scattering (SAXS), depolarized dynamic light scattering (DDLS), and cryogenic transmission electron microscopy (cryo-TEM) analyses. The central observations were as follows: (1) aggregate species of sizes in the range of several hundred nanometers have been independently revealed by SLS, DLS, and DDLS analyses for both solvent systems. (2) DDLS and cryo-TEM measurements further revealed that while C60 clusters are notably anisotropic (rod-like) in chlorobenzene, they are basically isotropic (spherical) in toluene. (3) Detailed analyses of combined SLS and SAXS profiles suggested that varied, yet self-similar, solvent-induced aggregate units were responsible for the distinct (mesoscale) aggregation features noted above. (4) From a dynamic perspective, specially commissioned DLS measurements ubiquitously displayed two relaxation modes (fast and slow mode), with the second (slow) mode being q (wave vector) independent. While the fast mode in both solvent systems was basically diffusive by nature and leads to geometrical features in good agreement with the above static analyses, the slow mode was analyzed and tentatively suggested to reflect the effect of mutual confinement. (5) Micron-scale aggregate morphology of drop-cast thin films displays similar contrasting features for the two solvent media used. Overall, this study suggests that solvent-induced, nanoscale, aggregate units may be a promising factor to control a hierarchy of microscopic aggregation properties of C60 solutions and thin films. PMID:27376417

  1. DFT study of hydrogen storage in Pd-decorated C60 fullerene

    NASA Astrophysics Data System (ADS)

    El Mahdy, A. M.

    2015-11-01

    Hydrogen storage reactions on Pd-doped C60 fullerene are investigated by using the state-of-the-art density functional theory calculations. The Pd atom prefers to bind at the bridge site between two hexagonal rings, and can bind up to four hydrogen molecules with average adsorption energies of 0.61, 0.45, 0.32, and 0.21 eV per hydrogen molecule. With no metal clustering, the system gravimetric capacities are expected to be as large as 5.8 wt%. While the desorption activation barriers of the complexes nH2 + Pd-C60 with n = 1 are outside the department of energy (DOE) domain (-0.2 to -0.6 eV), the desorption activation barriers of the complexes nH2 + Pd-C60 with n = 2-4 are inside this domain. While the interaction of 1H2 with Pd + C60 is irreversible at 459 K, the interaction of 2H2 with Pd + C60 is reversible at 529 K. The hydrogen storage of the irreversible 1H2 + Pd-C60 and reversible 2H2 + Pd-C60 interactions are characterised in terms of densities of states, infrared, Raman, and proton magnetic resonance spectra, electrophilicity, and statistical thermodynamic stability.

  2. Mapping intermolecular bonding in C60

    PubMed Central

    Sundqvist, Bertil

    2014-01-01

    The formation of intermolecular bonds in C60 has been investigated in detail at pressures below 2.2 GPa and up to 750 K. Fullerene samples were heated in a temperature gradient to obtain data on the formation of dimers and low-dimensional polymers along isobars. Intermolecular bonding was analyzed ex situ by Raman scattering, using both intramolecular modes and intermolecular stretching modes. Semi-quantitative reaction maps are given for the formation of dimers and chains. The activation energy for dimer formation decreases by 0.2 meV pm−1 when intermolecular distances decrease and dimer formation is noticeably affected by the rotational state of molecules. Above 400–450 K larger oligomers are formed; below 1.4 GPa most of these are disordered, with small domains of linear chains, but above this the appearance of stretching modes indicates the existence of ordered one-dimensional polymers. At the highest pressures and temperatures two-dimensional polymers are also observed. PMID:25145952

  3. EPR study of radical reactions of C 60 dimer connected by a silicon bridge and single bond (C 60SiPh 2C 60)

    NASA Astrophysics Data System (ADS)

    Tumanskii, B. L.; Kalina, O. G.; Sokolov, V. I.; Chistyakov, A. L.; Stankevich, I. V.; Han, A.; Murata, Y.; Komatsu, K.

    2004-09-01

    Radical reactions of C 60 dimer connected by a silicon bridge and single bond (C 60SiPh 2C 60) were studied by EPR-spectroscopy. Attack of phosphoryl radicals or 2,2,6,6-tetramethylpiperidine- N-oxyl on the silicon atom leads to radical substitution of the fullerene and formation of a new fullerenyl radical, the structure of the former being confirmed by quantum-chemical calculations (DFT). The formation of only one type of spin-adduct on addition of phosphoryl radicals to the fullerene core is associated with small distortion of the fullerene cage in C 60SiPh 2C 60. Geometry of fullerene core in dimer differs only slightly from C 60 owing probably to flexibility of Si-C and C-C bonds which share a five-membered ring.

  4. Properties Of N@C60-Derived Peapods

    NASA Astrophysics Data System (ADS)

    Gembus, A.; Simon, F.; Jánossy, A.; Kuzmany, H.; Dinse, K.-P.

    2004-09-01

    Using pulsed EPR techniques, the basic spin relaxation properties of N@C60-based peapods were determined. In contrast to narrow line spectra typical for N@C60 in solid solution or in a C60 matrix, substantial line broadening is observed for the SWCNT-encapsulated N@C60 molecules, which might be indicative for uniaxial cage distortion by interaction with the nanotube.

  5. IR, NIR, and UV Absorption Spectroscopy of C60(2+) and C60(3+) in Neon Matrixes.

    PubMed

    Kern, Bastian; Strelnikov, Dmitry; Weis, Patrick; Böttcher, Artur; Kappes, Manfred M

    2014-02-01

    C60(2+) and C60(3+) were produced by electron-impact ionization of sublimed C60 and charge-state-selectively codeposited onto a gold mirror substrate held at 5 K together with neon matrix gas containing a few percent of the electron scavengers CO2 or CCl4. This procedure limits charge-changing of the incident fullerene projectiles during matrix isolation. IR, NIR, and UV-vis spectra were then measured. Ten IR absorptions of C60(2+) were identified. C60(3+) was observed to absorb in the NIR region close to the known vibronic bands of C60(+). UV spectra of C60, C60(+), and C60(2+) were almost indistinguishable, consistent with a plasmon-like nature of their UV absorptions. The measurements were supported by DFT and TDDFT calculations, revealing that C60(2+) has a singlet D5d ground state whereas C60(3+) forms a doublet of Ci symmetry. The new results may be of interest regarding the presence of C60(2+) and C60(3+) in space. PMID:26276592

  6. Investigation of Photochemical Properties of C60 Aggregates in Water

    EPA Science Inventory

    As an emerging new material with unique structure and properties, the behavior and fate of Buckminster fullerene (C60) in natural waters has gained increasing attention. Although the water solubility of C60 is extremely low, the formation of C60 aggregates in water could alter th...

  7. Retention of Aqu/C60 Nanoparticles on Quartz Surfaces

    EPA Science Inventory

    Studies have shown that C60 fullerene can form stable suspensions of colloidal sized particles in water resulting in C60 aqueous concentrations many orders of magnitude above C60’s aqueous solubility. These studies have raised concern over the mobility and distribution of fuller...

  8. Screening of C60 crystallization using a microfluidic system.

    PubMed

    Shinohara, Kyosuke; Fukui, Takeshi; Abe, Hiroaki; Sekimura, Naoto; Okamoto, Koji

    2006-07-18

    We have carried out screening of C60 crystallization using a simple liquid/liquid interfacial precipitation method in a microfluidic device. By controlling the time, temperature, and concentration, various metastable phases of C60 crystals were found, including tubes, spheres, open-ended hollow columns, stars, branches, and trees. The obtained C60 crystal shapes are similar to those of snow crystals. These findings suggest an urgent need to screen C60 crystallization for the development of fullerene C60 drugs. PMID:16830986

  9. C60 -induced Devil's Staircase transformation on a Pb/Si(111) wetting layer

    DOE PAGESBeta

    Wang, Lin -Lin; Johnson, Duane D.; Tringides, Michael C.

    2015-12-03

    Density functional theory is used to study structural energetics of Pb vacancy cluster formation on C60/Pb/Si(111) to explain the unusually fast and error-free transformations between the “Devil's Staircase” (DS) phases on the Pb/Si(111) wetting layer at low temperature (~110K). The formation energies of vacancy clusters are calculated in C60/Pb/Si(111) as Pb atoms are progressively ejected from the initial dense Pb wetting layer. Vacancy clusters larger than five Pb atoms are found to be stable with seven being the most stable, while vacancy clusters smaller than five are highly unstable, which agrees well with the observed ejection rate of ~5 Pbmore » atoms per C60. Furthermore, the high energy cost (~0.8 eV) for the small vacancy clusters to form indicates convincingly that the unusually fast transformation observed experimentally between the DS phases, upon C60 adsorption at low temperature, cannot be the result of single-atom random walk diffusion but of correlated multi-atom processes.« less

  10. C60-induced Devil's Staircase transformation on a Pb/Si(111) wetting layer

    NASA Astrophysics Data System (ADS)

    Wang, Lin-Lin; Johnson, Duane D.; Tringides, Michael C.

    2015-12-01

    Density functional theory is used to study structural energetics of Pb vacancy cluster formation on C60/Pb /Si (111 ) to explain the unusually fast and error-free transformations between the "Devil's Staircase" (DS) phases on the Pb/Si(111) wetting layer at low temperature (˜110 K ). The formation energies of vacancy clusters are calculated in C60/Pb /Si (111 ) as Pb atoms are progressively ejected from the initial dense Pb wetting layer. Vacancy clusters larger than five Pb atoms are found to be stable with seven being the most stable, while vacancy clusters smaller than five are highly unstable, which agrees well with the observed ejection rate of ˜5 Pb atoms per C60. The high energy cost (˜0.8 eV) for the small vacancy clusters to form indicates convincingly that the unusually fast transformation observed experimentally between the DS phases, upon C60 adsorption at low temperature, cannot be the result of single-atom random walk diffusion but of correlated multi-atom processes.

  11. C60-Induced Devil's Staircase Transformation on Pb/Si(111) Wetting Layer

    NASA Astrophysics Data System (ADS)

    Wang, Lin-Lin; Johnson, Duane D.; Tringides, Michael C.

    Density functional theory is used to study structural energetics of Pb vacancy cluster formation on C60/Pb/Si(111) to explain the unusually fast and error-free transformations between the ``Devil's Staircase'' (DS) phases on the Pb/Si(111) wetting layer at low temperature (~110 K). The formation energies of vacancy clusters are calculated in C60/Pb/Si(111) as Pb atoms are progressively ejected from the initial dense Pb wetting layer. Vacancy clusters larger than 5 Pb atoms are found to be stable with 7 being the most stable, while vacancy clusters smaller than 5 are highly unstable, which agrees well with the observed ejection rate of ~5 Pb atoms per C60. The high energy cost (~0.8 eV) for the small vacancy clusters to form indicates convincingly that the unusually fast transformation observed experimentally between the DS phases, upon C60 adsorption at low temperature, cannot be the result of single-atom random walk diffusion but correlated multi-atom processes. DOE Office of Science, Basic Energy Sciences from the Divisions of MSE (DE-AC02-07CH1135) and Ames Lab LDRD. Ames Laboratory is operated for DOE by Iowa State University under contract DE-AC02-07CH11358.

  12. Colloidal Properties of Aqueous Fullerenes: Isoelectric Points and Aggregation Kinetics of C60 and C60 Derivatives

    EPA Science Inventory

    Aqueous colloidal suspensions of C-60 (aqu/C-60) and the C-60 derivatives PCBM ([6,6]-phenyl C-61-butyric acid methyl ester) and the corresponding butyl and octyl esters, PCBB and PCBO (aqu/PCB-R, where R is an alkyl group), were produced by stirring in double deionized water for...

  13. C60 fullerenes from combustion of common fuels.

    PubMed

    Tiwari, Andrea J; Ashraf-Khorassani, Mehdi; Marr, Linsey C

    2016-03-15

    Releases of C60 fullerenes to the environment will increase with the growth of nanotechnology. Assessing the potential risks of manufactured C60 requires an understanding of how its prevalence in the environment compares to that of natural and incidental C60. This work describes the characterization of incidental C60 present in aerosols generated by combustion of five common fuels: coal, firewood, diesel, gasoline, and propane. C60 was found in exhaust generated by all five fuels; the highest concentrations in terms of mass of C60 per mass of particulate matter were associated with diesel and coal. Individual aerosols from these combustion processes were examined by transmission electron microscopy. No relationship was found between C60 content and either the separation of graphitic layers (lamellae) within the particles, nor the curvature of those lamellae. Estimated global emissions of incidental C60 to the atmosphere from coal and diesel combustion range from 1.6 to 6.3 t yr(-1), depending upon combustion conditions. These emissions may be similar in magnitude to the total amount of manufactured C60 produced on an annual basis. Consequent loading of incidental C60 to the environment may be several orders of magnitude higher than has previously been modeled for manufactured C60. PMID:26789363

  14. Superconductivity at 45 K in Rb/Tl codoped C60 and C60/C70 mixtures

    NASA Astrophysics Data System (ADS)

    Iqbal, Zafar; Baughman, Ray H.; Khare, Sandeep; Murthy, N. S.; Ramakrishna, B. L.; Bornemann, Hans J.; Morris, Donald E.

    1991-11-01

    The appearance of superconductivity at relatively high temperatures in alkali metal-doped C60 fullerene provides the challenge to both understand the nature and origin of the superconductivity and to determine the upper limit of the superconducting transition temperature (Tc). Toward the latter goal, it is shown that doping with potassium-thallium and rubidium-thallium alloys in the 400 to 430 C temperature range increases the Tc of C60/C70 mixtures to 25.6 K and above 45 K, respectively. Similar increases in Tc were also observed on analogous doping of pure C60. Partial substitution of potassium with thallium in interstitial sites between C60 molecules is suggested by larger observed unit cell parameters than for the K3C60 and K4C60 phases. Contrary to previous results for C60 doped with different alkali metals, such expansion does not alone account for the changes in critical temperature.

  15. Buckminsterfullerene C60 — a surface with curvature and interesting properties

    NASA Astrophysics Data System (ADS)

    Rosén, Arne; Wästberg, Bo

    1992-05-01

    Molecular cluster calculations within the local density approximation have been performed in a study of the electronic structure of the truncated icosahedral C60 also known as "Buckminsterfullerene" and C60 doped with K, B and N. Evaluated ionisation energies for C60 are found to be in good agreement with recently observed gas phase and solid-state photoelectron spectra. Excitation energies evaluated in the 1-10 eV energy range are also found to reproduce UV, IR and HREELS spectra. Calculations for the KC60 molecule, with the K atom located at the centre of the cage, show how the valence electron from K is transferred to the LUMO state of the bare C60 molecule. Doping with a B or N atom in the centre of the cage creates a different structure with a partly occupied level in the band gap, similar to the donor and acceptor levels in traditionally doped semiconductors. Doping by substitution of two of the carbon atoms in the cage with X = B or N, as modelled with the C58X2 cluster, gives a different structure with a splitting of the HOMO and LUMO levels in the bare C60 molecule.

  16. C60-DOM interactions and effects on C60 apparent solubility: a molecular mechanics and density functional theory study.

    PubMed

    Wang, Zhuang; Chen, Jingwen; Sun, Qian; Peijnenburg, Willie J G M

    2011-08-01

    Dissolved organic matter (DOM) plays a critical role in the transport of carbon nano-particles (e.g. C(60)) in the aquatic environment. However, the mechanism for C(60)-DOM interactions and its environmental implications needs further investigations. In this study, the interaction of C(60) with relevant reference compounds of DOM (DOM(R)) is computationally simulated by molecular mechanics and density functional theory (DFT). All the C(60)-DOM(R) complexes are firstly optimized by classical annealing, and then DFT using the Dmol(3) code. The adsorption energies of C(60) on DOM(R) were computed. The computed electrostatic potential indicates that DOM(R) are electron acceptors in the C(60)-DOM(R) complexes, and the thermodynamic calculations indicate that electrostatic interaction is the dominant driving force for the C(60)-gallic acid complexation process in water. The presence of DOM(R) increases the apparent water solubility of C(60). It is also observed that the C(60) apparent water solubility decrease with the increase of the energy gaps of frontier molecular orbitals (E(LUMO)-E(HOMO)) for each C(60)-DOM(R) complex. These findings indicate that computational simulation is an important tool for predicting the behavior and fate of carbon nano-particles in the aquatic environment. PMID:21419494

  17. Epitaxial Templating of C60 with a Molecular Monolayer.

    PubMed

    Rochford, L A; Jones, T S; Nielsen, C B

    2016-09-01

    Commensurate epitaxial monolayers of truxenone on Cu (111) were employed to template the growth of monolayer and bilayer C60. Through the combination of STM imaging and LEED analysis we have demonstrated that C60 forms a commensurate 8 × 8 overlayer on truxenone/Cu (111). Bilayers of C60 retain the 8 × 8 periodicity of templated monolayers and although Kagome lattice arrangements are observed these are explained with combinations of 8 × 8 symmetry. PMID:27540868

  18. "Soft" metallic contact to isolated C60 molecules.

    PubMed

    Glowatzki, Hendrik; Bröker, Benjamin; Blum, Ralf-Peter; Hofmann, Oliver T; Vollmer, Antje; Rieger, Ralph; Müllen, Klaus; Zojer, Egbert; Rabe, Jürgen P; Koch, Norbert

    2008-11-01

    C60 adsorbed on a monolayer of hexaazatriphenylene-hexanitrile (HATCN) on Ag(111) is investigated by ultraviolet photoelectron spectroscopy (UPS) and scanning tunneling microscopy. UPS and quantum-mechanical modeling show that HATCN chemisorbed on Ag(111) displays metallic character. This metallic molecular layer decouples C60 electronically from the Ag substrate and simultaneously acts both as template for the stable adsorption of isolated C60 molecules at room temperature and as "soft" metallic contact for subsequently deposited molecules. PMID:18954123

  19. Synthesis and characterization of tetrakis-silylated C60 isomers.

    PubMed

    Maeda, Yutaka; Rahman, G M Aminur; Wakahara, Takatsugu; Kako, Masahiro; Okamura, Mutsuo; Sato, Soichi; Akasaka, Takeshi; Kobayashi, Kaoru; Nagase, Shigeru

    2003-08-22

    A photochemical reaction of C(60) with disilane in a 2:3 ratio affords the isomer mixture of the tetrakis-adduct of C(60)((t)BuPh(2)Si)(4) as the major product. The use of a three-stage HPLC separation system isolated three of their isomers. Their structural assignments were based on FAB mass, UV-vis, NMR, and cyclic voltammetry (CV) measurements. The CV analysis showed that the terakis-adduct has lower oxidation and higher reduction potentials than the bis-adduct C(60)((t)BuPh(2)Si)(2) and the parent C(60). PMID:12919050

  20. Photoexcitation of a volume plasmon in C60 ions

    SciTech Connect

    Scully, S.W.J.; Emmons, E.D.; Gharaibeh, M.F.; Phaneuf, R.A.; Kilcoyne, A.L.D.; Schlachter, A.S.; Schippers, S.; Muller, A.; Chakraborty, H.S.; Madjet, M.E.; Rost, J.M.

    2005-06-21

    Neutral C60 is well known to exhibit a giant resonance in its photon absorption spectrum near 20 eV. This is associated with a surface plasmon, where delocalized electrons oscillate as a whole relative to the ionic cage. Absolute photoionization cross-section measurements for C60(sup+), C60(sup2+), and C60(sup3+) ions in the 17 75eV energy range show an additional resonance near 40 eV. Time-dependent density functional calculations confirm the collective nature of this feature, which is characterized as a dipole-excited volume plasmon made possible by the special fullerene geometry.

  1. Electron spin resonance study of Rb xC 60 and K xC 60 powders

    NASA Astrophysics Data System (ADS)

    Feng, S. Q.; Jia, Y. Q.; Zhu, S. L.; Fu, J. S.; Wu, E.; Mao, J. C.; Han, R. S.; Gu, Z. N.; Zhou, X. H.; Jin, Z. X.

    1993-11-01

    Rb and K doped C 60 compounds are prepared by the vapor-solid reaction method. Superconductive shielding fraction is determined as 35-75% for Rb xC 60 and 10% for K xC 60. Electron spin resonance (ESR) measurements in absorption mode are performed in the temperature range of 5-300 K. A strong ESR signal at g=2.002 for Rb xC 60 and g=2.003 for K xC 60 has been observed. The g-value is nearly independent upon temperature for both Rb xC 60 and K xC 60 while the linewidth behaves differently, increasing from 2.0 G at 5 K to 6.0 G at 250 K in Rb xC 60 and remaining constant of 2.3 G in K xC 60. No drastic change of the ESR spectra is observed with the onset of superconductivity, leading to a conclusion that the observed dominant ESR signal originates from a non-superconducting phase.

  2. Aqueous solubilization of C60 fullerene by natural protein surfactants, latherin and ranaspumin-2.

    PubMed

    Vance, Steven J; Desai, Vibhuti; Smith, Brian O; Kennedy, Malcolm W; Cooper, Alan

    2016-01-01

    C60 fullerene is not soluble in water and dispersion usually requires organic solvents, sonication or vigorous mechanical mixing. However, we show here that mixing of pristine C60 in water with natural surfactant proteins latherin and ranaspumin-2 (Rsn-2) at low concentrations yields stable aqueous dispersions with spectroscopic properties similar to those previously obtained by more vigorous methods. Particle sizes are significantly smaller than those achieved by mechanical dispersion alone, and concentrations are compatible with clusters approximating 1:1 protein:C60 stoichiometry. These proteins can also be adsorbed onto more intractable carbon nanotubes. This promises to be a convenient way to interface a range of hydrophobic nanoparticles and related materials with biological macromolecules, with potential to exploit the versatility of recombinant protein engineering in the development of nano-bio interface devices. It also has potential consequences for toxicological aspects of these and similar nanoparticles. PMID:27214760

  3. [Stability of C60 nanoparticles in aquatic systems].

    PubMed

    Fang, Hua; Shen, Bing-Bing; Jing, Jie; Lu, Ji-Lai; Wang, Yuan

    2014-04-01

    The influences of storage time, pH, electrolytes and organic matters on the stability of two different suspensions of C60 nanoparticles were investigated. The results showed that the C60 nanoparticles prepared by solvent substitution (C60/son) were more stable than that prepared by prolonged stirring (C60/aq), and kept stable for a period of time. Higher pH enhanced the stability of C60 nanoparticles. The presence of electrolyte made a dramatic decrease in the surface zeta potential and an increase in the particle size. The aggregation process of C60 nanoparticles exhibited slow and rapid regions, which was found to be consistent with the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal stability. The critical coagulation concentration (CCC) values of C60/son, obtained from the intersection of the interpolated lines through the slow and fast regions, were estimated as 321 mmol x L(-1) NaCl, 316 mmol x L(-1) KCl, 9.6 mmol x L(-1) MgCl2 and 6.7 mmol x L(-1) CaCl2. The CCC values of C60/aq were estimated as 295 mmol x L(-1) NaCl, 278 mmol x L(-1) KCl, 7.8 mmol x L(-1) MgCl2 and 5.9 mmol x L(-1) CaCl2, which were much higher than their concentrations in natural waters. The presence of humic acid enhanced the stability of C60 nanoparticles, which was attributable to steric repulsion. Therefore, C60 nanoparticles will keep relatively stable in typical aquatic environments. PMID:24946585

  4. Axis-dependent magnetic behavior of C60 and C60(10+). consequences of spherical aromatic character.

    PubMed

    Muñoz-Castro, A

    2015-06-28

    The magnetic response of C60 has been studied and compared to its spherical aromatic counterpart C60(10+), focusing on the overall and local shielding tensors. A high axis dependence behavior at the outside region of the structure is characterized, unravelling a characteristic pattern of the local chemical shift anisotropy as a consequence of the spherical aromatic behavior. PMID:26022142

  5. Coherence of Auger and inter-Coulombic decay processes in the photoionization of Ar@C60 versus Kr@C60

    NASA Astrophysics Data System (ADS)

    Magrakvelidze, Maia; De, Ruma; Javani, Mohammad H.; Madjet, Mohamed E.; Manson, Steven T.; Chakraborty, Himadri S.

    2016-04-01

    For the asymmetric spherical dimer of an endohedrally confined atom and a host fullerene, an innershell vacancy of either system can decay through the continuum of an outer electron hybridized between the systems. Such decays, viewed as coherent superpositions of the single-center Auger and two-center inter-Coulombic (ICD) amplitudes, are found to govern leading decay mechanisms in noble-gas endofullerenes, and are likely omnipresent in this class of nanomolecules. A comparison between resulting autoionizing resonances calculated in the photoionization of Ar@C60 and Kr@C60 exhibits details of the underlying processes. Contribution to the Topical Issue "Atomic Cluster Collisions (7th International Symposium)", edited by Gerardo Delgado Barrio, Andrey Solov'Yov, Pablo Villarreal, Rita Prosmiti.

  6. Shock compression and equation of state of C60 fullerite

    NASA Astrophysics Data System (ADS)

    Milyavskiy, Vladimir; Khishchenko, Konstantin; Utkin, Alexander; Yakushev, Vladislav; Zhuk, Andrey; Fortov, Vladimir

    2007-06-01

    Recently, we have experimentally studied shock compressibility of C60 fullerite and sound velocity in shock-compressed fullerite [1]. The Hugoniot of C60 fullerite had a set of peculiarities. Appearance of a rather hard carbon phase was detected at shock pressure ˜ 9 GPa. We assume that it is a 2D-polymerized C60 phase. With increase of shock pressure, destruction of this phase and formation of a graphite-like carbon occurs. With further increase of shock pressure, the graphite- like carbon transforms to a diamond-like phase. If shock pressure is higher than ˜ 33 GPa, shock compressibility of C60 fullerite is determined by the thermodynamic properties of the diamond-like phase. The results of the shock-wave measurements were used for the description of thermodynamic properties of C60 fullerite and products of its transformations in a wide range of pressures and temperatures. A semiempirical equation of state for the simple cubic phase of C60 fullerite is proposed. The EOS we have developed for fullerite C60 provides a consistent representation of the available experimental data. The work was supported by RFBR. [1] Milyavskiy V.V., Utkin A.V., Zhuk A.Z., Yakushev V.V. and Fortov V.E. Diamond and Rel. Mat. 14 (2005) 1920.

  7. C60 fullerene soil sorption, biodegradation, and plant uptake.

    PubMed

    Avanasi, Raghavendhran; Jackson, William A; Sherwin, Brie; Mudge, Joseph F; Anderson, Todd A

    2014-01-01

    Assessments of potential exposure to fullerenes and their derivatives in the environment are important, given their increasing production and use. Our study focused on fate processes that determine the movement and bioavailability of fullerenes in soil. We evaluated the sorption, biodegradation, and plant uptake of C60 fullerene using (14)C-labeled C60 solutions in water produced by either solvent exchange with tetrahydrofuran or sonication/extended mixing in water. Organic carbon appeared to have an important influence on C60 soil sorption. The log Koc values for (14)C60 were equivalent for sandy loam and silt loam (3.55 log[mL/g]) but higher for loam (4.00 log[mL/g]), suggesting that other factors, such as pH, clay content and mineralogy, and cation exchange capacity, also influence C60 soil sorption. There was little (14)CO2 production in the silt loam or the sandy loam soil after 754 and 328 days, respectively, suggesting high resistance of C60 to mineralization in soil. Plant uptake was generally low (∼7%), with most of the uptaken (14)C accumulating in the roots (40-47%) and smaller amounts of accumulation in the tuber (22-23%), stem (12-16%), and leaves (18-22%). Our results indicate that C60 released to the environment will not be highly bioavailable but will likely persist in soil for extended periods. PMID:24521447

  8. Optimal High-TC Superconductivity in Cs3C60

    NASA Astrophysics Data System (ADS)

    Harshman, Dale; Fiory, Anthony

    The highest superconducting transition temperatures in the (A1-xBx)3C60 superconducting family are seen in the A15 and FCC structural phases of Cs3C60 (optimized under hydrostatic pressure), exhibiting measured values for near-stoichiometric samples of TC0 meas . = 37.8 K and 35.7 K, respectively. It is argued these two Cs-intercalated C60 compounds represent the optimal materials of their respective structures, with superconductivity originating from Coulombic e- h interactions between the C60 molecules, which host the n-type superconductivity, and mediating holes associated with the Cs cations. A variation of the interlayer Coulombic pairing model [Harshman and Fiory, J. Supercond. Nov. Magn. 28 ̲, 2967 (2015), and references therein] is introduced in which TC0 calc . ~ 1 / lζ , where l relates to the mean spacing between interacting charges on surfaces of the C60 molecules, and ζ is the average radial distance between the surface of the C60 molecules and the neighboring Cs cations. For stoichiometric Cs3C60, TC0 calc . = 38.08 K and 35.67 K for the A15 and FCC macrostructures, respectively; the dichotomy is attributable to differences in ζ.

  9. Superconductivity at 52 K in hole-doped C60.

    PubMed

    Schön, J H; Kloc, C; Batlogg, B

    2000-11-30

    Superconductivity in electron-doped C60 was first observed almost ten years ago. The metallic state and superconductivity result from the transfer of electrons from alkaline or alkaline-earth ions to the C60 molecule, which is known to be a strong electron acceptor. For this reason, it is very difficult to remove electrons from C60--yet one might expect to see superconductivity at higher temperatures in hole-doped than in electron-doped C60, because of the higher density of electronic states in the valence band than in the conduction band. We have used the technique of gate-induced doping in a field-effect transistor configuration to introduce significant densities of holes into C60. We observe superconductivity over an extended range of hole density, with a smoothly varying transition temperature Tc that peaks at 52 K. By comparison with the well established dependence of Tc on the lattice parameter in electron-doped C60, we anticipate that Tc values significantly in excess of 100 K should be achievable in a suitably expanded, hole-doped C60 lattice. PMID:11117735

  10. C60 as a Probe for Astrophysical Environments

    NASA Astrophysics Data System (ADS)

    Brieva, A. C.; Gredel, R.; Jäger, C.; Huisken, F.; Henning, T.

    2016-08-01

    The C60 molecule has been recently detected in a wide range of astrophysical environments through its four active intramolecular vibrational modes (T 1u) near 18.9, 17.4, 8.5, and 7.0 μm. The strengths of the mid-infrared emission bands have been used to infer astrophysical conditions in the fullerene-rich regions. Widely varying values of the relative intrinsic strengths (RIS) of these four bands are reported in laboratory and theoretical papers, which impedes the derivation of the excitation mechanism of C60 in the astrophysical sources. The spectroscopic analysis of the C60 samples produced with our method delivers highly reproducible RIS values of 100, 25 ± 1, 26 ± 1 and 40 ± 4. A comparison of the inferred C60 emission band strengths with the astrophysical data shows that the observed strengths cannot be explained in terms of fluorescent or thermal emission alone. The large range in the observed 17.4 μm/18.9 μm emission ratios indicates that either the emission bands contain significant contributions from emitters other than C60, or that the population distribution among the C60 vibrational modes is affected by physical processes other than thermal or UV excitation, such as chemo-luminescence from nascent C60 or possibly Poincaré fluorescence resulting from an inverse internal energy conversion. We have carefully analyzed the effect of the weakly active fundamental modes and second order modes in the mid-infrared spectrum of C60, and propose that neutral C60 is the carrier of the unidentified emission band at 6.49 μm which has been observed in fullerene-rich environments.

  11. Orientation-dependent C-60 electronic structures revealed byphotoemission spectroscopy

    SciTech Connect

    Brouet, V.; Yang, W.L.; Zhou, X.J.; Choi, H.J.; Louie, S.G.; Cohen, M.L.; Goldoni, A.; Parmigiani, F.; Hussain, Z.; Shen, Z.X.

    2008-01-17

    We observe, with angle-resolved photoemission, a dramaticchange in the electronic structure of two C60 monolayers, deposited,respectively, on Ag (111) and (100) substrates, and similarly doped withpotassium to half filling of the C60 lowest unoccupied molecular orbital.The Fermi surface symmetry, the bandwidth, and the curvature of thedispersion at gamma point are different. Orient ations of the C60molecules on the two substrates are known to be the main structuraldifference between the two monolayers, and we present new band-structurecalculations for some of these orientations. We conclude thatorientations play a key role in the electronic structure offullerides.

  12. New Phases of C60 Synthesized at High Pressure

    NASA Astrophysics Data System (ADS)

    Iwasa, Y.; Arima, T.; Fleming, R. M.; Siegrist, T.; Zhou, O.; Haddon, R. C.; Rothberg, L. J.; Lyons, K. B.; Carter, H. L., Jr.; Hebard, A. F.; Tycko, R.; Dabbagh, G.; Krajewski, J. J.; Thomas, G. A.; Yagi, T.

    1994-06-01

    The fullerene C60 can be converted into two different structures by high pressure and temperature. They are metastable and revert to pristine C60 on reheating to 300^circC at ambient pressure. For synthesis temperatures between 300^circ and 400^circC and pressures of 5 gigapascals, a nominal face-centered-cubic structure is produced with a lattice parameter a_o = 13.6 angstroms. When treated at 500^circ to 800^circC at the same pressure, C60 transforms into a rhombohedral structure with hexagonal lattice parameters of a_o = 9.22 angstroms and c_o = 24.6 angstroms. The intermolecular distance is small enough that a chemical bond can form, in accord with the reduced solubility of the pressure-induced phases. Infrared, Raman, and nuclear magnetic resonance studies show a drastic reduction of icosahedral symmetry, as might occur if the C60 molecules are linked.

  13. Formation of buckminsterfullerene (C60) in interstellar space

    PubMed Central

    Berné, Olivier; Tielens, A. G. G. M.

    2012-01-01

    Buckminsterfullerene (C60) was recently confirmed as the largest molecule identified in space. However, it remains unclear how and where this molecule is formed. It is generally believed that C60 is formed from the buildup of small carbonaceous compounds in the hot and dense envelopes of evolved stars. Analyzing infrared observations, obtained by Spitzer and Herschel, we found that C60 is efficiently formed in the tenuous and cold environment of an interstellar cloud illuminated by strong ultraviolet (UV) radiation fields. This implies that another formation pathway, efficient at low densities, must exist. Based on recent laboratory and theoretical studies, we argue that polycyclic aromatic hydrocarbons are converted into graphene, and subsequently C60, under UV irradiation from massive stars. This shows that alternative—top-down—routes are key to understanding the organic inventory in space. PMID:22198841

  14. Formation of buckminsterfullerene (C60) in interstellar space

    NASA Astrophysics Data System (ADS)

    Berné, Olivier; Tielens, Alexander G. G. M.

    2012-01-01

    Buckminsterfullerene (C60) was recently confirmed to be the largest molecule identified in space. However, it remains unclear how, and where this molecule is formed. It is generally believed that C60 is formed from the build up of small carbonaceous compounds, in the hot and dense envelopes of evolved stars. Analyzing infrared observations, obtained by Spitzer and Herschel, we found that C60 is efficiently formed in the tenuous and cold environment of an interstellar cloud illuminated by strong ultraviolet (UV) radiation fields. This implies that another formation pathway, efficient at low densities, must exist. Based on recent laboratory and theoretical studies, we argue that Polycyclic Aromatic Hydrocarbons are converted into graphene, and subsequently C60, under UV irradiation from massive stars. This shows that alternative - top-down - routes are key to understanding the organic inventory in space.

  15. Aggregation and Deposition of C60 in Aqueous Systems

    EPA Science Inventory

    The extremely low water solubility of many fullerenes precludes aqueous solution processing for engineering applications and minimizes the potential for fullerene environmental effects in aqueous environments. However, studies have shown that C60 fullerene can form stable colloi...

  16. Structure and photophysics in C 60-micellar solutions

    NASA Astrophysics Data System (ADS)

    Eastoe, Julian; Crooks, Esther R.; Beeby, Andrew; Heenan, Richard K.

    1995-11-01

    Routes to the preparation of monomeric and colloidal C 60 in micellar solutions of non-ionic surfactants are described. UV-visible spectra and small-angle neutron scattering provide clear evidence for these two different forms. The micelles serve to stabilise the excited triplet state 3C 60 and the lifetime τT is increased by a factor of 3 as compared to 3C 60 in toluene. Furthermore, with monomeric dispersions in the presence of the electron donor DABCO, the radical anion C 60- is formed, with an unusually long lifetime τA = 16 ms. This lifetime is approximately 270 times longer than for γ-cyclodextrin. stabilised systems.

  17. Energetics and structural stability of Cs3C60

    SciTech Connect

    Saito, Susumu; Umemoto, Koichiro; Louie, Steven G.; Cohen, MarvinL.

    2003-12-15

    Using the ab initio pseudo potential total-energy method and the density-functional theory, we study the energetics of face-centered-cubic Cs3C60 which is a material of great interest as a possible high transition-temperature superconductor. At the optimized lattice constant the volume per C60 is found to be smaller than the most stable hexagon-coordination A15 phase, while the total energy of the fcc phase is about 0.9 eV higher than the A15 phase. These results indicate that a low-temperature and high-pressure synthesis method might be a possible way to produce the fcc Cs3C60 phase. In addition, it is also found that the A15 Cs3C60 should show a phase transformation from a hexagon-coordination phase to a pentagon-coordination phase under hydrostatic pressure.

  18. Mechanical characterization of C60 whiskers by MEMS bend testing

    NASA Astrophysics Data System (ADS)

    Larsson, M. P.; Lucyszyn, S.

    2009-04-01

    Little has been published on the mechanical characteristics of C60 whiskers, due to the inherent difficulties in physically mounting such small test samples. Earlier reported results suggested Young's modulus values of 32 and 54 GPa, with 130 and 160 micron diameter C60 nanowhiskers, respectively, using compressive deformation techniques. In our work, an experimental bespoke silicon-based microelectromechanical system has been developed to extract an other value. 1th as been found, through parameter extraction techniques, that a Young's modulus of only ~ 2 GPa is obtained with a C60 whisker having a diameter of 4 microns. By including the previously published data points, there is now strong evidence to suggest an inverse proportionality relationship between the Young's modulus and the diameter of a C60 whisker.

  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. Hemicarceplexes modify the solubility and reduction potentials of C60.

    PubMed

    Wong, Tzu-Huan; Chang, Jia-Cheng; Lai, Chien-Chen; Liu, Yi-Hung; Peng, Shie-Ming; Chiu, Sheng-Hsien

    2014-04-18

    A highly stable C60-incarcerated hemicarceplex, which retains its molecular integrity after heating at 523 K in air for at least 3 h, significantly increases the solubility of C60 in nonpolar solvents and increases the reduction potentials of the entrapped fullerene. Modification with [(η(5)-C5Me5)Ru(II)](+) dramatically increases the solubility of this hemicarceplex in polar, protic solvents (e.g., MeOH). PMID:24665822

  1. Tailorable acceptor C(60-n)B(n) and donor C(60-m)N(m) pairs for molecular electronics.

    PubMed

    Xie, Rui-Hua; Bryant, Garnett W; Zhao, Jijun; Smith, Vedene H; Di Carlo, Aldo; Pecchia, Alessandro

    2003-05-23

    Our first-principles calculations demonstrate that C(60-n)B(n) and C(60-m)N(m) can be engineered as the acceptors and donors, respectively, needed for molecular electronics by properly controlling the dopant number n and m in C60. We show that acceptor C48B12 and donor C48N12 are promising components for molecular rectifiers, carbon nanotube-based n-p-n (p-n-p) transistors, and p-n junctions. PMID:12785911

  2. Soil microbial response to photo-degraded C60 fullerenes.

    PubMed

    Berry, Timothy D; Clavijo, Andrea P; Zhao, Yingcan; Jafvert, Chad T; Turco, Ronald F; Filley, Timothy R

    2016-04-01

    Recent studies indicate that while unfunctionalized carbon nanomaterials (CNMs) exhibit very low decomposition rates in soils, even minor surface functionalization (e.g., as a result of photochemical weathering) may accelerate microbial decay. We present results from a C60 fullerene-soil incubation study designed to investigate the potential links between photochemical and microbial degradation of photo-irradiated C60. Irradiating aqueous (13)C-labeled C60 with solar-wavelength light resulted in a complex mixture of intermediate products with decreased aromaticity. Although addition of irradiated C60 to soil microcosms had little effect on net soil respiration, excess (13)C in the respired CO2 demonstrates that photo-irradiating C60 enhanced its degradation in soil, with ∼ 0.78% of 60 day photo-irradiated C60 mineralized. Community analysis by DGGE found that soil microbial community structure was altered and depended on the photo-treatment duration. These findings demonstrate how abiotic and biotic transformation processes can couple to influence degradation of CNMs in the natural environment. PMID:26774781

  3. Elucidating the Significance of the ``Nano-Effect'' in Determining the Mobility of C60 Nanoparticles in Saturated Porous Media

    NASA Astrophysics Data System (ADS)

    Jia, Q.; Brant, J.

    2010-12-01

    Fullerenes are all carbon molecules that may exist in a variety of geometries, such as cages, cylinders, and planar sheets. Buckminsterfullerene (C60) is one type of fullerene that has received considerable interest from the scientific community for its use in commercial applications (bio-medical technologies, electronics, optics, and composites) and environmental implications (toxicity, mobility). Once released into the environment, the toxicity and bioavailability of C60 nanoparticles will be largely influenced by transport and retention processes in porous media. To date, many studies have investigated C60 mobility in saturated porous media, which has relevance to both groundwater protection and potable treatment by filtration methods. Previous research efforts have determined that the technique used for dispersing the C60 in water, chemistry of the dispersion solution (pH, ionic composition/strength), and Darcy velocity all affect C60 mobility. However, far less attention has been directed toward determining the impact of nanoparticle size. In other words, is there a nano-effect for C60, and if it exists to what extent does it alter C60 mobility in saturated porous media. The overall objective of this study was to explore to what extent the size of the C60 clusters (nC60) affects their mobility in saturated porous media in order to determine if the nano-effect does indeed exist for these systems. Nanoparticle mobility in two relatively well-characterized porous media, glass spheres and quartz sand, was assessed as a function of solution chemistry and Darcy velocity. The surface charge of the collector media was modified to elucidate the significance of charge interactions for nanoparticles. Preliminary results suggest that nC60 mobility increases as particle size decreases, supporting the belief that the nano-effect is indeed a real phenomenon.

  4. Target Plate Material Influence on Fullerene-C60 Laser Desorption/Ionization Efficiency.

    PubMed

    Zeegers, Guido P; Günthardt, Barbara F; Zenobi, Renato

    2016-04-01

    Systematic laser desorption/ionization (LDI) experiments of fullerene-C60 on a wide range of target plate materials were conducted to gain insight into the initial ion formation in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The positive and negative ion signal intensities of precursor, fragment, and cluster ions were monitored, varying both the laser fluence (0-3.53 Jcm(-2)) and the ion extraction delay time (0-950 ns). The resulting species-specific ion signal intensities are an indication for the ionization mechanisms that contribute to LDI and the time frames in which they operate, providing insight in the (MA)LDI primary ionization. An increasing electrical resistivity of the target plate material increases the fullerene-C60 precursor and fragment anion signal intensity. Inconel 625 and Ti90/Al6/V4, both highly electrically resistive, provide the highest anion signal intensities, exceeding the cation signal intensity by a factor ~1.4 for the latter. We present a mechanism based on transient electrical field strength reduction to explain this trend. Fullerene-C60 cluster anion formation is negligible, which could be due to the high extraction potential. Cluster cations, however, are readily formed, although for high laser fluences, the preferred channel is formation of precursor and fragment cations. Ion signal intensity depends greatly on the choice of substrate material, and careful substrate selection could, therefore, allow for more sensitive (MA)LDI measurements. Graphical Abstract ᅟ. PMID:26894888

  5. Target Plate Material Influence on Fullerene-C60 Laser Desorption/Ionization Efficiency

    NASA Astrophysics Data System (ADS)

    Zeegers, Guido P.; Günthardt, Barbara F.; Zenobi, Renato

    2016-04-01

    Systematic laser desorption/ionization (LDI) experiments of fullerene-C60 on a wide range of target plate materials were conducted to gain insight into the initial ion formation in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The positive and negative ion signal intensities of precursor, fragment, and cluster ions were monitored, varying both the laser fluence (0-3.53 Jcm-2) and the ion extraction delay time (0-950 ns). The resulting species-specific ion signal intensities are an indication for the ionization mechanisms that contribute to LDI and the time frames in which they operate, providing insight in the (MA)LDI primary ionization. An increasing electrical resistivity of the target plate material increases the fullerene-C60 precursor and fragment anion signal intensity. Inconel 625 and Ti90/Al6/V4, both highly electrically resistive, provide the highest anion signal intensities, exceeding the cation signal intensity by a factor ~1.4 for the latter. We present a mechanism based on transient electrical field strength reduction to explain this trend. Fullerene-C60 cluster anion formation is negligible, which could be due to the high extraction potential. Cluster cations, however, are readily formed, although for high laser fluences, the preferred channel is formation of precursor and fragment cations. Ion signal intensity depends greatly on the choice of substrate material, and careful substrate selection could, therefore, allow for more sensitive (MA)LDI measurements.

  6. Alkylation of C60. Reaction between C60 anions and tert-butyl chloride and mass spectrometry analysis

    NASA Astrophysics Data System (ADS)

    Bourcier, S.; Chaurand, P.; Ciot, C.; Della-Negra, S.; Fabre, C.; Greugny, V.; Marx, L.; Rassat, A.; Rousseau, A.

    1996-11-01

    Alkylation of C60 in tetrahydrofuran with tert-butyl chloride and lithium gives a variety of products. Adducts of general formula C60Hn(t-Bu)qOx(thf)y (where t-Bu is the tert-butyl group and thf the tetrahydrofuryl group (C4H7O)) have been detected by mass spectrometry, with n <= 8, q + y <= 18 and x = 0, 1, 2 depending on experimental conditions. IR and NMR spectra of products confirm these assignments.

  7. Structural and Electrical Investigation of C60-Graphene Vertical Heterostructures.

    PubMed

    Kim, Kwanpyo; Lee, Tae Hoon; Santos, Elton J G; Jo, Pil Sung; Salleo, Alberto; Nishi, Yoshio; Bao, Zhenan

    2015-06-23

    Graphene, with its unique electronic and structural qualities, has become an important playground for studying adsorption and assembly of various materials including organic molecules. Moreover, organic/graphene vertical structures assembled by van der Waals interaction have potential for multifunctional device applications. Here, we investigate structural and electrical properties of vertical heterostructures composed of C60 thin film on graphene. The assembled film structure of C60 on graphene is investigated using transmission electron microscopy, which reveals a uniform morphology of C60 film on graphene with a grain size as large as 500 nm. The strong epitaxial relations between C60 crystal and graphene lattice directions are found, and van der Waals ab initio calculations support the observed phenomena. Moreover, using C60-graphene heterostructures, we fabricate vertical graphene transistors incorporating n-type organic semiconducting materials with an on/off ratio above 3 × 10(3). Our work demonstrates that graphene can serve as an excellent substrate for assembly of molecules, and attained organic/graphene heterostructures have great potential for electronics applications. PMID:26027690

  8. Jellium model potentials for the C60 molecule and the photoionization of endohedral atoms, A@C60

    NASA Astrophysics Data System (ADS)

    Baltenkov, A. S.; Manson, S. T.; Msezane, A. Z.

    2015-09-01

    Approximating the C60 shell as a collection of carbon atoms, the potential experienced by a confined atom has been calculated within the framework of the self-consistent spherical jellium model. It has been found that the potential well in this model has a cusp-shaped Lorentz-like profile. The parameters of the model Lorentz-bubble potential (depth and thickness) have been selected so that in the potential well there would be an electronic level corresponding to the experimental electron affinity of the C60 molecule. The spatial distribution of the positive charge of the C-atomic nuclei and the negative charge of the electron clouds forming the electrostatic potential of C60, as a whole, has been analyzed using the Poisson equation. It is demonstrated that the often used radial square-well potential to approximate the C60 corresponds to a non-physical charge density for the C60 molecule. This analysis demonstrates that the phenomenological potentials simulating the C60 shell potential should belong to a family of potentials with a non-flat bottom and non-parallel potential walls similar to the Lorentz-bubble potential. The photoionization cross-sections of a hydrogen atom localized at the center of the C60 shell have been calculated as well. It is found that confinement oscillations in the cross-sections are exhibited within the framework of the cusp-shaped potential model and these oscillations are essentially the same as those in the case of the potential wells with well-defined borders (parallel walls), thereby demonstrating that the inherent characteristic distances of the potential, e.g., radii of the potential walls, or the distances between potential walls, are not necessary to produce confinement resonances; this should be a general result for atoms or molecules confined in near-spherical fullerenes.

  9. ESR study of superconducting K-doped C 60 "polymer"

    NASA Astrophysics Data System (ADS)

    Kinoshita, N.; Grigoryan, L. S.; Kinoshita, T.; Tokumoto, M.

    1997-03-01

    ESR measurements of the superconducting K-doped C 60 "polymer" were carried out, in order to clarify the difference from ordinary K-doped C 60, i.e. monomer. Observed ESR spectrum was simulated by four Lorentzian lines. The temperature dependences of the ESR linewidth, g factor and spin susceptibility are obtained for each ESR line. At room temperature the linewidth and g factor of the broadest ESR absorption line are, about 400 G and 2.01, respectively. The linewidths for other lines are 150, 53 and 16 G with the common g factor of 2.000. The linewidths of the ESR spectrum of superconducting K-doped C 60 "polymer" are found to be much broader than those of monomer sample. Similar to monomer sample, two absorption lines with weakly temperature-dependent intensity were observed, one of which disappeared (150 G width) below the super-conducting transition temperature ( Tc = 15 K).

  10. C60 + in Diffuse Clouds: Laboratory and Astronomical Comparison

    NASA Astrophysics Data System (ADS)

    Campbell, E. K.; Holz, M.; Maier, J. P.

    2016-07-01

    The wavelengths of the strongest absorptions in the electronic spectrum of {{{C}}}60+ have been determined by experimental investigation into the perturbation caused by the helium in the laboratory spectra of {{{C}}}60+-{{{He}}}n(n=1{--}3). The extrapolation of these gives absorption bands of bare {{{C}}}60+ at 9348.4, 9365.2, 9427.8, 9577.0, and 9632.1 Å, with ±0.2 Å as the 2σ uncertainty. The laboratory data are compared with the complete set of astronomical observations reported in the literature. The spectral characteristics are found to be in agreement with five diffuse interstellar bands, for which the systematic uncertainties are larger than for the laboratory data.

  11. Radial vibrations of a sodium ion inside icosahedral C60

    NASA Technical Reports Server (NTRS)

    Ballester, J. L.; Dunlap, B. I.

    1992-01-01

    The very high symmetry of icosahedral C60 suggests that, as a first approximation, an atom trapped inside C60 would be subject to a potential that is radially symmetric about the center. All-electron local-density-functional calculations of the total energy of a sodium ion as a function of radial displacement from the center along the fivefold axis of C60 serve to refine such a radial potential. In particular, the calculations suggest studying potentials that have minima displaced from the center. An analytic functional form for a radial potential having a positive cusp at the origin is proposed, and the s-wave radial solutions of the corresponding Schroedinger equation are examined.

  12. A search for C60 in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    De Vries, M. S.; Reihs, K.; Wendt, H. R.; Golden, W. G.; Hunziker, H. E.; Fleming, R.; Peterson, E.; Chang, S.

    1993-01-01

    Analysis of interior samples of the Murchison meteorite by two routes yielded an upper limit of 2 ppb for its C60 content, as compared to parts per million levels for individual polycyclic aromatic hydrocarbons (PAHs ). Provided the samples contain an interstellar component, which is probable since Murchison hydrocarbons contain excess deuterium, this result argues against the ubiquitous presence of C60 in the interstellar medium. A possible explanation for the absence of C60 was found in experiments showing how PAHs replace fullerenes as stable end products when hydrogen is present during carbon condensation. As a secondary result we found high molecular weight PAHs in the Murchison and Allende meteorites. Coronene and its methyl derivatives are especially interesting since features in the coronene spectrum have been shown to match some of the unidentified interstellar infrared emission bands.

  13. Intermolecular artifacts in probe microscope images of C60 assemblies

    NASA Astrophysics Data System (ADS)

    Jarvis, Samuel Paul; Rashid, Mohammad Abdur; Sweetman, Adam; Leaf, Jeremy; Taylor, Simon; Moriarty, Philip; Dunn, Janette

    2015-12-01

    Claims that dynamic force microscopy has the capability to resolve intermolecular bonds in real space continue to be vigorously debated. To date, studies have been restricted to planar molecular assemblies with small separations between neighboring molecules. Here we report the observation of intermolecular artifacts over much larger distances in 2D assemblies of C60 molecules, with compelling evidence that in our case the tip apex is terminated by a C60 molecule (rather than the CO termination typically exploited in ultrahigh resolution force microscopy). The complete absence of directional interactions such as hydrogen or halogen bonding, the nonplanar structure of C60, and the fullerene termination of the tip apex in our case highlight that intermolecular artifacts are ubiquitous in dynamic force microscopy.

  14. Magnetic phases and relaxation effects in fullerite C60

    NASA Astrophysics Data System (ADS)

    Chigvinadze, J. G.; Buntar, V.; Ashimov, S. M.; Dolbin, A. V.

    2016-02-01

    A highly sensitive torsional vibration technique is used to study the magnetic properties of fullerite C60 (99.98%) at temperatures of 77-300 K in dynamic and static experiments. Vibrational energy absorption peaks associated with phase transitions and realignment of the magnetic structure of the fullerite are detected at T = 152, 195, 230, and 260 K. Relaxation magnetic processes in fullerite C60 at room temperature are studied. "Spontaneous" rotation of a motionless sample of fullerite freely suspended on an elastic filament is observed when external longitudinal or transverse magnetic fields are switched on. The direction of the "spontaneous" rotation changes with time. It is proposed that these phenomena are related to relaxation processes in the rotational subsystem of C60 molecular rotators, as well as to magnetic flux trapped in the fullerite and weakly damped eddy currents induced in the sample by the applied field.

  15. Charging C60 islands with the AFM tip.

    PubMed

    Hoff, Brice; Henry, Claude R; Barth, Clemens

    2016-01-01

    We show that electrons can be transferred on demand from an AFM tip into single bulk-like C60 islands, which are supported on the insulating NaCl(001) surface. We exemplify this by controlled charge-manipulation experiments conducted in ultrahigh vacuum by noncontact AFM (nc-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). KPFM shows a homogeneous contrast at the islands, which is a signature for an equal distribution of the electrons in the T1u band. The charge dissipates during half a day due to an interaction of the charged C60 islands with defects in the near surface region of NaCl. Our results open the perspective in photo-voltaics to study charge attachment, stability and charge exchange with the environment of any C60 bulk-like system. PMID:26617348

  16. Vibration-rotation spectroscopy of molecules trapped inside C60.

    PubMed

    Cross, R James

    2008-08-01

    A simple model is developed to treat the energy levels and spectroscopy of diatomic molecules inside C 60. The C 60 cage is treated as spherically symmetric, and the coupling to the C 60 vibrations is ignored. The remaining six degrees of freedom correspond to the vibrations and rotations of the diatomic molecule and the rattling vibration of the molecule inside the cage. By using conservation of angular momentum, we can remove two of these motions and simplify the calculations. The resulting energy levels are simple and can be labeled by a set of quantum numbers. The IR and Raman spectra look like those of gas-phase diatomic molecules at low temperatures. At higher temperatures, hot bands due to the low-frequency rattling mode appear, and the spectrum becomes congested, looking like a solution spectrum. PMID:18598014

  17. A study of thermally activated delayed fluorescence in C 60

    NASA Astrophysics Data System (ADS)

    Salazar, Filipa A.; Fedorov, Aleksandre; Berberan-Santos, Mário N.

    1997-06-01

    The existence of thermally activated delayed fluorescence in C 60 is demonstrated by the study of the temperature dependence (291-353 K) of the fluorescence intensity of C 60 degassed solutions. The determined singlet-triplet energy gap, 35 ± 2 kJ/mol, agrees with the value calculated from previously reported fluorescence and low temperature phosphorescence spectra for this molecule (35 kJ/mol). The estimated quantum yield of triplet formation, 0.8 ± 0.1, agrees with previous determinations. The fluorescence lifetime of C 60, also measured, τ = 1.1 ns, does not change appreciably with excitation wavelength, degassing nor with temperature, in the range 243-343 K.

  18. Ionisation of C60: is it temperature dependent?

    NASA Astrophysics Data System (ADS)

    Baba, M. Sai; Narasimhan, T. S. Lakshmi; Balasubramanian, R.; Mathews, C. K.

    1994-01-01

    In a recent paper, Drewello [T. Drewello, W. Kratschmer, M. Fieber-Erdmann and A. Ding, Int. J. Mass Spectrom. Ion Processes, 124 (1993) R1] reported a temperature dependent ionisation cross section for the formation of C2+60 in their photoionisation dynamic studies on C60 using synchrotron radiation. To check this, the ratio of ion intensities of C2+60 to that of C60 was determined as a function of temperature of C60 samples using a Knudsen effusion mass spectrometer. Our results indicate the absence of any temperature dependence of cross section for the formation of C2+60 in the temperature range of measurement (600-800 K) using electron impact ionisation.

  19. Charging C60 islands with the AFM tip

    NASA Astrophysics Data System (ADS)

    Hoff, Brice; Henry, Claude R.; Barth, Clemens

    2015-12-01

    We show that electrons can be transferred on demand from an AFM tip into single bulk-like C60 islands, which are supported on the insulating NaCl(001) surface. We exemplify this by controlled charge-manipulation experiments conducted in ultrahigh vacuum by noncontact AFM (nc-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). KPFM shows a homogeneous contrast at the islands, which is a signature for an equal distribution of the electrons in the T1u band. The charge dissipates during half a day due to an interaction of the charged C60 islands with defects in the near surface region of NaCl. Our results open the perspective in photo-voltaics to study charge attachment, stability and charge exchange with the environment of any C60 bulk-like system.We show that electrons can be transferred on demand from an AFM tip into single bulk-like C60 islands, which are supported on the insulating NaCl(001) surface. We exemplify this by controlled charge-manipulation experiments conducted in ultrahigh vacuum by noncontact AFM (nc-AFM), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). KPFM shows a homogeneous contrast at the islands, which is a signature for an equal distribution of the electrons in the T1u band. The charge dissipates during half a day due to an interaction of the charged C60 islands with defects in the near surface region of NaCl. Our results open the perspective in photo-voltaics to study charge attachment, stability and charge exchange with the environment of any C60 bulk-like system. Electronic supplementary information (ESI) available. See DOI: 10.1039/C5NR04541J

  20. 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.

  1. Effective medium theory for a system of C60 molecules

    NASA Astrophysics Data System (ADS)

    Moradi, Afshin

    2016-06-01

    An effective medium theory is developed to study the effective permittivity of a system of C60 molecules. We use a two-dimensional, spherical, two-fluid hydrodynamic model to describe the linear response of the π and σ electrons over the each C60 molecule. A general expression for the electromagnetic wave attenuation coefficient of the system is then deduced, and its functional dependence on the filling factor is presented. Furthermore, the dispersion characteristics of electromagnetic oscillations of the system are studied.

  2. Structure and dynamics of C60 molecules on Au(111)

    SciTech Connect

    Shin, Heekeun; Schwarze, A; Diehl, R D; Pussi, K; Colombier, A; Gaudry, E.; Ledieu, J; McGuirk, G M; Serkovic Loli, L N; Fournee, V; Wang, Lin-Lin; Schull, G; Berndt, R

    2014-06-01

    Earlier studies of C60 adsorption on Au(111) reported many interesting and complex features. We have performed coordinated low-energy electron diffraction, scanning tunneling microscopy (STM), and density functional theory studies to elucidate some of the details of the monolayer commensurate (2√3 × 2√3)R30° phase. We have identified the adsorption geometries of the two states that image as dim and bright in STM. These consist of a C60 molecule with a hexagon side down in a vacancy (hex-vac) and a C60 molecule with a carbon-carbon 6:6 bond down on a top site (6:6-top), respectively. We have studied the detailed geometries of these states and find that there is little distortion of the C60 molecules, but there is a rearrangement of the substrate near the C60 molecules. The two types of molecules differ in height, by about 0.7 Å, which accounts for most of the difference in their contrast in the STM images. The monolayer displays dynamical behavior, in which the molecules flip from bright to dim, and vice versa. We interpret this flipping as the result of the diffusion of vacancies in the surface layers of the substrate. Our measurements of the dynamics of this flipping from one state to the other indicate that the activation energy is 0.66 ± 0.03 eV for flips that involve nearest-neighbor C60 molecules, and 0.93 ± 0.03 for more distant flips. Based on calculated activation energies for vacancies diffusing in Au, we interpret these to be a result of surface vacancy diffusion and bulk vacancy diffusion. These results are compared to the similar system of Ag(111)-(2√3 × 2√3)R30°-C60. In both systems, the formation of the commensurate C60 monolayer produces a large number of vacancies in the top substrate layer that are highly mobile, effectively melting the interfacial metal layer at temperatures well below their normal melting temperatures.

  3. Quenching of fluorescence in C60 fulleropyrrolidines by chloroform

    NASA Astrophysics Data System (ADS)

    Parveen, Abdulrazack; Sughanya, Venkatesan; Nagarajan, Samuthira

    2016-01-01

    Functionalized [C60] fullerene, fulleropyrrolidines were synthesized and their photophysical properties are studied. The absorption and emission patterns are altered in fulleropyrrolidines, when compared with C60. Fluorescence of the molecules is quenched by CHCl3 in toluene solution at room temperature. Effect of nature and length of side chains in fulleropyrrolidine on quenching is investigated. Results suggested that the fluorescence intensity increased with increase in carbon chain length and the Stern-Volmer plot intercept values are indirectly proportional to the number of the carbons.

  4. Experimental and theoretical determination of the magnetic susceptibility of C60 and C70

    NASA Astrophysics Data System (ADS)

    Haddon, R. C.; Schneemeyer, L. F.; Waszczak, J. V.; Glarum, S. H.; Tycko, R.; Dabbagh, G.; Kortan, A. R.; Muller, A. J.; Mujsce, A. M.; Rosseinsky, M. J.; Zahurak, S. M.; Makhija, A. V.; Thiel, F. A.; Raghavachari, K.; Cockayne, E.; Elser, V.

    1991-03-01

    THE magnetic susceptibility of C60 and the possibility of magnetic-field-induced π-electron ring currents in this carbon spheroid have been of interest since the initial experiments on carbon clusters1. If the molecule is regarded as a sphere with a radius of 3.5 Å, on which 60 electrons are free to move, the Pauling ring-current model predicts a ring-current diamagnetic susceptibility 41 times the π-electron ring-current magnetic susceptibility of benzene with the field normal to the plane of the six-membered ring2,3. London theory predicts, however, that the π-electron ring currents in C60 should be weakly paramagnetic or diamagnetic, depending on the relative bond strengths used in the calculation2,3. With the availability of macroscopic quantities of C60 (ref. 4), it is now possible to study experimentally the magnetic properties of the molecule. Here we report on such measurements. We find that the diamagnetism of C60 is small, a result that we attribute to excited-state paramagnetic contributions to the π-electron ring-current magnetic susceptibility. Thus C60 seems to be an aromatic molecule with a vanishingly small π-electron ring-current magnetic susceptibility. We have performed similar measurements on C70, which indicate an appreciable π-electron diamagnetism, consistent with theoretical calculations. We attribute the differences in magnetic properties of these two molecules to their different fractions of five-membered ring structures. The fullerenes may thus constitute a class of compounds of 'ambiguous' aromatic character, traditional measures of which will not provide an adequate classification.

  5. Electronic properties and phase transitions of RbC60 and CsC60: Investigation by NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Tycko, R.; Dabbagh, G.; Murphy, D. W.; Zhu, Q.; Fischer, J. E.

    1993-09-01

    We report the results of 133Cs, 87Rb, and 13C NMR measurements on the alkali-metal fullerides CsC60 and RbC60. Measurements of NMR spectra and spin-lattice relaxation rates provide clear evidence for phase transitions near 300 K in both compounds, with substantial changes in their electronic properties at the phase transitions. The high-temperature phases are paramagnets, with an exchange coupling of roughly 2 cm-1 between electron spins that are localized primarily on C-60 ions. The 133Cs and 87Rb NMR frequency shifts and relaxation rates are determined by Fermi contact hyperfine couplings to the electron spins. The 13C relaxation rates are determined by dipolar hyperfine couplings. The electron-spin susceptibility is greatly reduced in the low-temperature phases

  6. 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.

  7. Electronically Excited C2 from Laser Photodissociated C60

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram; Scott, Carl D.; Nikolaev, Pavel; Smalley, Richard E.

    1999-01-01

    Spectral and transient emission measurements are made of radiation from products of laser excitation of buckminsterfullerene (C60) vapor diluted in argon at 973 K. The principal radiation is from the Swan band system of C2 and, at early times, also from a black body continuum. The C2 radiation is observed only when C60 is excited by green (532 nm) and not with IR (1064 nm) laser radiation at energy densities of about 1.5 J/square cm. Transient measurements indicate that there are two characteristic periods of decay of radiation. The first period, lasting about 2 micro seconds, has a characteristic decay time of about 0.3 micro seconds. The second period, lasting at least 50 micro seconds, has a characteristic decay time of about 5 micro seconds. These characteristic times are thought to be associated with cooling of C60 molecules or nanosized carbon particles during the early period; and with electronically excited C2 that is a decomposition product of laser excited C60, C58, ... molecules during the later period.

  8. Nitrogen-embedded buckybowl and its assembly with C60

    PubMed Central

    Yokoi, Hiroki; Hiraoka, Yuya; Hiroto, Satoru; Sakamaki, Daisuke; Seki, Shu; Shinokubo, Hiroshi

    2015-01-01

    Curved π-conjugated molecules have attracted considerable interest because of the unique properties originating from their curved π surface. However, the synthesis of such distorted molecules requires harsh conditions, which hamper easy access to heteroatom-containing curved π systems. Here we report the synthesis of a π-extended azacorannulene with nitrogen in its centre. The oxidation of 9-aminophenanthrene provides tetrabenzocarbazole, which is converted to the azabuckybowl through palladium-catalysed intramolecular coupling. The electron-donating nature and curved π surface of the azabuckybowl enable its tight association with C60 in solution and solid states. High charge mobility is observed for the azabuckybowl/C60 assembly. This compound may be of interest in the fields of curved π systems as fullerene hosts, anisotropic π donors and precursors to nitrogen-containing nanocarbon materials. PMID:26337912

  9. Quantum Bound States in a C-C60 System

    NASA Astrophysics Data System (ADS)

    Adam, R. M.; Sofianos, S. A.

    2015-03-01

    We investigate the quantum mechanical system of a carbon "test atom" in the proximity of a C60 molecule, both inside and outside the fullerene "cage". Two sets of bound states are found to exist, a deeply bound set inside the cage and another weakly bound set outside it. Tunnelling between these regions is highly unlikely to happen because of the extreme height and width of the potential barrier. However, we predict that a layer of atoms could be adsorbed onto C60 by forming a quantum mechanical bound state, with the adsorbed atoms being concentrated above the "panels" of the buckyball, consistent with "bucky onions" observed experimentally. Until now analysis of such fullerene systems has been via classical mechanics, but a quantum approach reveals new insights.

  10. 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.

  11. Photoionization and photofragmentation of the C60+ molecular ion

    NASA Astrophysics Data System (ADS)

    Baral, K. K.; Aryal, N. B.; Esteves-Macaluso, D. A.; Thomas, C. M.; Hellhund, J.; Lomsadze, R.; Kilcoyne, A. L. D.; Müller, A.; Schippers, S.; Phaneuf, R. A.

    2016-03-01

    Cross-section measurements are reported for single and double photoionization of C60+ ions in the photon energy range 18-150 eV accompanied by the loss of zero to seven pairs of carbon atoms, as well as for fragmentation without ionization resulting in loss of two to eight pairs of C atoms in the photon energy range 18-65 eV. Absolute measurements were performed by merging a beam of C60+ molecular ions with a beam of monochromatized synchrotron radiation. Product channels involving dissociation yielding smaller fullerene fragment ions account for nearly half of the total measured oscillator strength in this energy range. The sum of cross sections for the measured product channels is compared to a published calculation of the total photoabsorption cross section of neutral C60 based on time-dependent density-functional theory. This comparison and an accounting of oscillator strengths indicate that with the exception of C58+, the most important product channels resulting from photoabsorption were accounted for in the experiment. Threshold energies for the successive removal of carbon atom pairs accompanying photoionization are also determined from the measurements.

  12. C60-derived nanobaskets: stability, vibrational signatures, and molecular trapping.

    PubMed

    dos Santos, S G; Pires, M S; Lemos, V; Freire, V N; Caetano, E W S; Galvão, D S; Sato, F; Albuquerque, E L

    2009-09-30

    C(60)-derived nanobaskets, with chemical formulae (symmetry point group) C(40)H(10) (C(5v)), C(39)H(12) (C(3v)), C(46)H(12) (C(2v)), were investigated. Molecular dynamic simulations (MDSs) indicate that the molecules preserve their bonding frame for temperatures up to 300 K (simulation time 100 ps), and maintain atomic cohesion for at least 4 ps at temperatures up to 3500 K. The infrared spectra of the C(60)-derived nanobaskets were simulated through density functional theory (DFT) calculations, allowing for the attribution of infrared signatures specific to each carbon nanobasket. The possibility of using C(60)-derived nanobaskets as molecular containers is demonstrated by performing a DFT study of their bonding to hydrogen, water, and L-alanine. The carbon nanostructures presented here show a higher bonding energy (approximately 1.0 eV), suggesting that a family of nanostructures, C(n)-derived (n = 60,70,76,80, etc) nanobaskets, could work as molecular containers, paving the way for future developments such as tunable traps for complex molecular systems. PMID:19724106

  13. Blocking the passage: C60 geometrically clogs K(+) channels.

    PubMed

    Calvaresi, Matteo; Furini, Simone; Domene, Carmen; Bottoni, Andrea; Zerbetto, Francesco

    2015-05-26

    Classical molecular dynamics (MD) simulations combined with docking calculations, potential of mean force estimates with the umbrella sampling method, and molecular mechanic/Poisson-Boltzmann surface area (MM-PBSA) energy calculations reveal that C60 may block K(+) channels with two mechanisms: a low affinity blockage from the extracellular side, and an open-channel block from the intracellular side. The presence of a low affinity binding-site at the extracellular entrance of the channel is in agreement with the experimental results showing a fast and reversible block without use-dependence, from the extracellular compartment. Our simulation protocol suggests the existence of another binding site for C60 located in the channel cavity at the intracellular entrance of the selectivity filter. The escape barrier from this binding site is ∼21 kcal/mol making the corresponding kinetic rate of the order of minutes. The analysis of the change in solvent accessible surface area upon C60 binding shows that binding at this site is governed purely by shape complementarity, and that the molecular determinants of binding are conserved in the entire family of K(+) channels. The presence of this high-affinity binding site conserved among different K(+) channels may have serious implications for the toxicity of carbon nanomaterials. PMID:25873341

  14. In situ x-ray photoelectron spectroscopic and density-functional studies of Si atoms adsorbed on a C60 film.

    PubMed

    Onoe, Jun; Nakao, Aiko; Hara, Toshiki

    2004-12-01

    The interaction between C(60) and Si atoms has been investigated for Si atoms adsorbed on a C(60) film using in situ x-ray photoelectron spectroscopy (XPS) and density-functional (DFT) calculations. Analysis of the Si 2p core peak identified three kinds of Si atoms adsorbed on the film: silicon suboxides (SiO(x)), bulk Si crystal, and silicon atoms bound to C(60). Based on the atomic percent ratio of silicon to carbon, we estimated that there was approximately one Si atom bound to each C(60) molecule. The Si 2p peak due to the Si-C(60) interaction demonstrated that a charge transfer from the Si atom to the C(60) molecule takes place at room temperature, which is much lower than the temperature of 670 K at which the charge transfer was observed for C(60) adsorbed on Si(001) and (111) clean surfaces [Sakamoto et al., Phys. Rev. B 60, 2579 (1999)]. The number of electrons transferred between the C(60) molecule and Si atom was estimated to be 0.59 based on XPS results, which is in good agreement with the DFT result of 0.63 for a C(60)Si with C(2v) symmetry used as a model cluster. Furthermore, the shift in binding energy of both the Si 2p and C 1s core peaks before and after Si-atom deposition was experimentally obtained to be +2.0 and -0.4 eV, respectively. The C(60)Si model cluster provides the shift of +2.13 eV for the Si 2p core peak and of -0.28 eV for the C 1s core peak, which are well corresponding to those experimental results. The covalency of the Si-C(60) interaction was also discussed in terms of Mulliken overlap population between them. PMID:15634092

  15. Density functional calculation of superatomic molecular orbitals in C60: First truly converged results on a real grid mesh

    NASA Astrophysics Data System (ADS)

    Drake, Kyle; Bonacum, Jason; Zhang, Guo-Ping

    2014-03-01

    The molecular structure of Buckminster fullerene (C60) allows for electron delocalization in all of the pi-bonding electrons of the molecule. This coupled with the symmetry of the molecule allows for the formation of super-atomic molecular orbitals (SAMOs) similar to those observed in aluminum clusters. The SAMOs behave as if the molecule that they belong to is a single atom. We compute the eigenstates of C60 compulationally using density functional theory (DFT) and a grid mesh. Using larger radii also allows us to accurately describe SAMOs and test the convergence of our data. The results are interesting because for the first time, we can show the true converged super atomic orbitals in C60. Indiana State University SURE Program, Department of Energy, Indiana State University Department of Physics, and Indiana State University Center for Student Creativity and Research.

  16. Molecular dynamics and the phase transition in solid C60

    NASA Astrophysics Data System (ADS)

    Tycko, R.; Dabbagh, G.; Fleming, R. M.; Haddon, R. C.; Makhija, A. V.; Zahurak, S. M.

    1991-09-01

    The molecular reorientational dynamics in two phases of solid C60 with C-13 NMR measurements are characterized. A change in the nature of the dynamics, indicated by a change in kinetic parameters extracted from spin-lattice relaxation data, occurs at the phase transition at 260 K. Above the transition, the molecules appear to execute continuous rotational diffusion; below the transition, they appear to jump between symmetry-equivalent orientations. This interpretation is consistent with the X-ray-diffraction results of Heiney et al. (1991) as well as the NMR relaxation and spectral data.

  17. C60 Secondary Ion Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

    SciTech Connect

    Smith, Donald F.; Robinson, Errol W.; Tolmachev, Aleksey V.; Heeren, Ronald M.; Pasa-Tolic, Ljiljana

    2011-12-15

    Secondary ion mass spectrometry (SIMS) has seen increased application for high spatial chemical imaging of complex biological surfaces. The advent and commercial availability of cluster and polyatomic primary ion sources (e.g. Au and Bi cluster and buckminsterfullerene (C60)) provide improved secondary ion yield and decreased fragmentation of surface species, thus accessibility to intact molecular ions. Despite developments in primary ion sources, development of mass spectrometers to fully exploit their advantages has been limited. Tandem mass spectrometry for identification of secondary ions is highly desirable, but implementation has proven to be difficult. Similarly, high mass resolution and high mass measurement accuracy would greatly improve the chemical specificity of SIMS. Here we combine, for the first time, the advantages of a C60 primary ion source with the ultra-high mass resolving power and high mass measurement accuracy of Fourier transform ion cyclotron resonance mass spectrometry. Mass resolving power in excess of 100,000 (m/Δm50%) is demonstrated, with mass measurement accuracies below 3 parts-per-million. Imaging of mouse brain tissue at 40 μm pixel size is shown. Tandem mass spectrometry of ions from biological tissue is demonstrated and molecular formulae can be assigned to fragment ions.

  18. C60-dyad aggregates: Self-organized structures in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Guskova, O. A.; Varanasi, S. R.; Sommer, J.-U.

    2014-10-01

    Extensive full-atomistic molecular dynamics simulations are performed to study the self-organization of C60-fullerene dyad molecules in water, namely phenyl-C61-butyric acid methyl ester and fulleropyrrolidines, which have two elements of ordering, the hydrophobic fullerene cage and the hydrophilic/ionic group. While pristine fullerene or phenyl-C61-butyric acid methyl ester forms spherical droplets in order to minimize the surface tension, the amphiphilic nature of charged solute molecules leads to the formation of supramolecular assemblies having cylindrical shape driven by charge repulsion between the ionic groups located on the surface of the aggregates. We show that formation of non-spherical micelles is the geometrical consequence if the fullerene derivatives are considered as surfactants where the ionized groups are only hydrophilic unit. The agglomeration behavior of fullerenes is evaluated by determining sizes of the clusters, solvent accessible surface areas, and shape parameters. By changing the size of the counterions from chloride over iodide to perchlorate we find a thickening of the cylinder-like structures which can be explained by stronger condensation of larger ions and thus partial screening of the charge repulsion on the cluster surface. The reason for the size dependence of counterion condensation is the formation of a stronger hydration shell in case of small ions which in turn are repelled from the fullerene aggregates. Simulations are also in good agreement with the experimentally observed morphologies of decorated C60-nanoparticles.

  19. Theoretical study of the structures and first hyperpolarizabilities of C60Cl n and Li@C60Cl n (n = 4, 6, 8, 10).

    PubMed

    Song, Yao-Dong; Wang, Liang; Wu, Li-Ming

    2016-06-01

    We recently reported (Song Y-D et al., 2016, J Mol Model 22:50) that doping with Li greatly affects the static first hyperpolarizability of C60Cl2. In this work, with a view to creating nonlinear optical materials with high thermodynamic stability and wide transparent regions, a series of Li@C60Cl n (n = 4, 6, 8, 10) were designed. The structures, electrostatic potentials, electronic structures, absorption spectra, and linear and nonlinear optical properties of C60Cl n and Li@C60Cl n were systematically investigated using density functional theory (DFT) methods. The results of our calculations indicated that the stability of these molecules decreases in the order Li@C60Cl10 > Li@C60Cl8 > Li@C60Cl6 > Li@C60Cl4. It is clear that the number of Cl atoms greatly influences the stability of Li@C60Cl n . Li@C60Cl n showed greater thermodynamic stability than Li@C60Cl2. We also investigated the first hyperpolarizabilities of Li@C60Cl n and found them to be 2973, 3640, 4307, and 2627 au for n = 4, 6, 8, and 10, respectively-higher than that of Li@C60Cl2. Finally, we noted that the transparent region could be modulated by increasing the number of Cl atoms: Li@C60Cl n possess wider transparent regions than that of Li@C60Cl2. We therefore believe that this study has highlighted an effective method for designing nonlinear optical materials with high thermodynamic stability and wide transparent regions. PMID:27188724

  20. Two-dimensional van der Waals C60 molecular crystal

    PubMed Central

    Reddy, C. D.; Gen Yu, Zhi; Zhang, Yong-Wei

    2015-01-01

    Two-dimensional (2D) atomic crystals, such as graphene and transition metal dichalcogenides et al. have drawn extraordinary attention recently. For these 2D materials, atoms within their monolayer are covalently bonded. An interesting question arises: Can molecules form a 2D monolayer crystal via van der Waals interactions? Here, we first study the structural stability of a free-standing infinite C60 molecular monolayer using molecular dynamic simulations, and find that the monolayer is stable up to 600 K. We further study the mechanical properties of the monolayer, and find that the elastic modulus, ultimate tensile stress and failure strain are 55–100 GPa, 90–155 MPa, and 1.5–2.3%, respectively, depending on the stretching orientation. The monolayer fails due to shearing and cavitation under uniaxial tensile loading. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the monolayer are found to be delocalized and as a result, the band gap is reduced to only 60% of the isolated C60 molecule. Interestingly, this band gap can be tuned up to ±30% using strain engineering. Owing to its thermal stability, low density, strain-tunable semi-conducting characteristics and large bending flexibility, this van der Waals molecular monolayer crystal presents aplenty opportunities for developing novel applications in nanoelectronics. PMID:26183501

  1. Electronic and ionic conductivities in superionic Li4C60

    NASA Astrophysics Data System (ADS)

    Quintavalle, D.; Márkus, B. G.; Jánossy, A.; Simon, F.; Klupp, G.; Győri, M. A.; Kamarás, K.; Magnani, G.; Pontiroli, D.; Riccò, M.

    2016-05-01

    The 10 GHz microwave conductivity, σ (T ) and high field, 222 GHz electron spin resonance (HF-ESR) of Li4C60 fulleride is measured in a wide temperature range. We suggest that the majority of ESR active sites and at least some of the charge carriers for σ (T ) are electrons bound to a small concentration of surplus or vacancy ions in the polymer phase. Both σ (T ) and the ESR line shape depend on ionic motion. A change of the activation energy of σ (T ) at 125 K coincides with the onset of the ionic DC conductivity. The ESR line shape is determined mainly by Li ionic motion within octahedral voids below 150 K. At higher temperatures, fluctuations due to ionic diffusion change the environment of defects from axial to effectively isotropic on the ESR time scale. σ (T ) data up to 700 K through the depolymerization transition confirm that the monomeric phase of Li4C60 is a metal.

  2. Hot electron spin transport in C60 fullerene

    NASA Astrophysics Data System (ADS)

    Hueso, Luis Eduardo; Gobbi, Marco; Bedoya-Pinto, Amilcar; Golmar, Federico; Llopis, Roger; Casanova, Felix

    2012-02-01

    Carbon-based molecular materials are interesting for spin transport application mainly due to their small sources of spin relaxation [1]. However, spin coherence lengths reported in many molecular films do not exceed a few tens of nanometers [2]. In this work we will present results showing how hot spin-polarized electrons injected well above the Fermi level in C60 fullerene films travel coherently for hundreds of nanometers. We fabricated hot-electron vertical transistors, in which the current created across an Al/Al2O3 junction is polarized by a metallic Co/Cu/Py spin valve trilayer and subsequently injected in the molecular thin film. This geometry allows us to determine the energy level alignment at each interface between different materials. Moreover, the collector magnetocurrent excess 85%, even for C60 films thicknesses of 300 nm. We believe these results show the importance of hot spin-polarized electron injection and propagation in molecular materials. [1] V. Dediu, L.E. Hueso, I. Bergenti, C. Taliani, Nature Mater. 8, 707 (2009) [2] M. Gobbi, F. Golmar, R. Llopis, F. Casanova, L.E. Hueso, Adv. Mater. 23, 1609 (2011)

  3. Two-dimensional van der Waals C60 molecular crystal

    NASA Astrophysics Data System (ADS)

    Reddy, C. D.; Gen Yu, Zhi; Zhang, Yong-Wei

    2015-07-01

    Two-dimensional (2D) atomic crystals, such as graphene and transition metal dichalcogenides et al. have drawn extraordinary attention recently. For these 2D materials, atoms within their monolayer are covalently bonded. An interesting question arises: Can molecules form a 2D monolayer crystal via van der Waals interactions? Here, we first study the structural stability of a free-standing infinite C60 molecular monolayer using molecular dynamic simulations, and find that the monolayer is stable up to 600 K. We further study the mechanical properties of the monolayer, and find that the elastic modulus, ultimate tensile stress and failure strain are 55-100 GPa, 90-155 MPa, and 1.5-2.3%, respectively, depending on the stretching orientation. The monolayer fails due to shearing and cavitation under uniaxial tensile loading. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the monolayer are found to be delocalized and as a result, the band gap is reduced to only 60% of the isolated C60 molecule. Interestingly, this band gap can be tuned up to ±30% using strain engineering. Owing to its thermal stability, low density, strain-tunable semi-conducting characteristics and large bending flexibility, this van der Waals molecular monolayer crystal presents aplenty opportunities for developing novel applications in nanoelectronics.

  4. Methoxylation of Singly Bonded 1,4-1',4'-BnC60-C60Bn Dimer: Preferential Formation of 1,4-C60 Adduct with Sterically Less Demanding Addends and Stability Difference between 1,2- and 1,4-OMe(Bn)C60.

    PubMed

    He, Fa-Gui; Li, Zong-Jun; Gao, Xiang

    2016-08-01

    Methoxylation of the singly bonded 1,4-1',4'-BnC60-C60Bn dimer afforded 1,4-OMe(Bn)C60, a 1,4-C60 adduct with sterically less demanding addends, as the major adduct. The situation was different from that of direct functionalization of C60, where 1,2-OMe(Bn)C60 was obtained as the major product. The reaction was studied with in situ vis-NIR spectroscopy and computational calculations to obtain a better understanding of this unusual regioselectivity. The stability difference between 1,2- and 1,4-OMe(Bn)C60 was studied. PMID:27387300

  5. Evidence for endohedral muonium in K(x) C60 and consequences for electronic structure

    NASA Technical Reports Server (NTRS)

    Kiefl, R. F.; Duty, T. L.; Schneider, J. W.; Macfarlane, A.; Chow, K.; Elzey, J. W.; Mendels, P.; Morris, G. D.; Brewer, J. H.; Ansaldo, E. J.

    1992-01-01

    Positive muons injected into solid C60, K4C60, and K6C60 form vacuumlike muonium with a (6-12) percent probability. Observation of coherent spin precession of muonium establishes that all three materials are nonmagnetic and nonconducting at low temperatures. From the temperature dependence of the signals we estimate the electronic band gaps in K4C60 and K6C60 to be considerably smaller than in C60. The similarity of the muonium centers supports a model in which a muonium atom is caged inside the C60 molecule in pure C60 or the C60 exp -x molecular ion in K(x)C60.

  6. On structural features of fullerene C60 dissolved in carbon disulfide: complementary study by small-angle neutron scattering and molecular dynamic simulations.

    PubMed

    Avdeev, M V; Tropin, T V; Bodnarchuk, I A; Yaradaikin, S P; Rosta, L; Aksenov, V L; Bulavin, L A

    2010-04-28

    The parameters of fullerene C(60) dissolved in carbon disulfide CS(2) are analyzed by small-angle neutron scattering (SANS) in a wide interval of momentum transfer. To exclude the influence of nonequilibrium conditions, the solutions are prepared without applying shaking, stirring or ultrasound. No indication of the equilibrium cluster state of C(60) (with the cluster size below 60 nm) in the final solutions is revealed. Molecular dynamic simulations are complementary used to find out the partial volume of C(60) in CS(2) and the scattering contribution of the solvent organization at the interface with the fullerene molecule, which is shown to be small. Among several approaches for describing SANS data the preference is given to the model, which takes into account the presence of stable C(60) dimers (comprising 10% of the total particle number density) in the solution. PMID:20441296

  7. Energetics and structural characterization of C60 polymerization in BN and carbon nanopeapods

    NASA Astrophysics Data System (ADS)

    Trave, Andrea; Ribeiro, Filipe J.; Louie, Steven G.; Cohen, Marvin L.

    2004-11-01

    As in the case of carbon nanotubes, also boron nitride nanotubes may host arrays of C60 molecules and form a nanopeapod (NPP). The observed separation between C60 molecules in BN NPP’s is consistently shorter than in carbon NPP’s, which influences their electronic properties. Here we report on total-energy pseudopotential density functional theory (DFT) calculations for polymerized and nonpolymerized C60 chains, and optimize their atomic structures to provide a description of their energetic landscape. A fully polymerized C60 chain and a C60 dimer are found to be more stable than nonpolymerized C60 , respectively, by 0.89 and 0.38eV/C60 . The geometry and energetics of an encapsulated C60 chain is not significantly different with respect to the isolated molecule. Encapsulation energies in BN and carbon NPP’s are, respectively, 1.56 and 1.67eV/C60 , which are significantly larger than the calculated activation energy for C60 polymerization, supporting the hypothesis that encapsulated C60 ’s in NPP’s are partially polymerized. Band structure analysis show that polymerization does not affect the gap width of the C60 chain. BN NPP’s are semiconductors with a gap width determined by the C60 . The lowest unoccupied C60 states lie just above the Fermi level in metallic carbon NPP’s and charge transfert could take place, affecting the C60 geometry.

  8. First-principles investigation of organic photovoltaic materials C60, C70, [C60]PCBM , and bis-[C60]PCBM using a many-body G0W0 -Lanczos approach

    NASA Astrophysics Data System (ADS)

    Qian, Xiaofeng; Umari, Paolo; Marzari, Nicola

    2015-06-01

    We present a first-principles investigation of the excited-state properties of electron acceptors in organic photovoltaics including C60, C70, [6,6]-phenyl-C61-butyric-acid-methyl-ester ([C60]PCBM ), and bis-[C60]PCBM using many-body perturbation theory within the Hedin's G0W0 approximation and an efficient Lanczos approach. Calculated vertical ionization potentials (VIP) and vertical electron affinities (VEA) of C60 and C70 agree very well with experimental values measured in the gas phase. The density of states of all three molecules is also compared to photoemission and inverse photoemission spectra measured on thin films, and they exhibit a close agreement—a rigid energy-gap renormalization owing to intermolecular interactions in the thin films. In addition, it is shown that the low-lying unoccupied states of [C60]PCBM are all derived from the highest-occupied molecular orbitals and the lowest-unoccupied molecular orbitals of fullerene C60. The functional side group in [C60]PCBM introduces a slight electron transfer to the fullerene cage, resulting in small decreases of both VIP and VEA. This small change of VEA provides a solid justification for the increase of open-circuit voltage when replacing fullerene C60 with [C60]PCBM as the electron acceptor in bulk heterojunction polymer solar cells.

  9. C60 fullerene localization and membrane interactions in RAW 264.7 immortalized mouse macrophages

    NASA Astrophysics Data System (ADS)

    Russ, K. A.; Elvati, P.; Parsonage, T. L.; Dews, A.; Jarvis, J. A.; Ray, M.; Schneider, B.; Smith, P. J. S.; Williamson, P. T. F.; Violi, A.; Philbert, M. A.

    2016-02-01

    There continues to be a significant increase in the number and complexity of hydrophobic nanomaterials that are engineered for a variety of commercial purposes making human exposure a significant health concern. This study uses a combination of biophysical, biochemical and computational methods to probe potential mechanisms for uptake of C60 nanoparticles into various compartments of living immune cells. Cultures of RAW 264.7 immortalized murine macrophage were used as a canonical model of immune-competent cells that are likely to provide the first line of defense following inhalation. Modes of entry studied were endocytosis/pinocytosis and passive permeation of cellular membranes. The evidence suggests marginal uptake of C60 clusters is achieved through endocytosis/pinocytosis, and that passive diffusion into membranes provides a significant source of biologically-available nanomaterial. Computational modeling of both a single molecule and a small cluster of fullerenes predicts that low concentrations of fullerenes enter the membrane individually and produce limited perturbation; however, at higher concentrations the clusters in the membrane causes deformation of the membrane. These findings are bolstered by nuclear magnetic resonance (NMR) of model membranes that reveal deformation of the cell membrane upon exposure to high concentrations of fullerenes. The atomistic and NMR models fail to explain escape of the particle out of biological membranes, but are limited to idealized systems that do not completely recapitulate the complexity of cell membranes. The surprising contribution of passive modes of cellular entry provides new avenues for toxicological research that go beyond the pharmacological inhibition of bulk transport systems such as pinocytosis.There continues to be a significant increase in the number and complexity of hydrophobic nanomaterials that are engineered for a variety of commercial purposes making human exposure a significant health concern

  10. Solubility of C60 and PCBM in Organic Solvents.

    PubMed

    Wang, Chun I; Hua, Chi C

    2015-11-12

    The ability to correlate fullerene solubility with experimentally or computationally accessible parameters can significantly facilitate nanotechnology nowadays for a wide range of applications, while providing crucial insight into optimum design of future fullerene species. To date, there has been no single relationship that satisfactorily describes the existing data clearly manifesting the effects of solvent species, system temperature, and isomer. Using atomistic molecular dynamics simulations on two standard fullerene species, C60 and PCBM ([6,6]-phenyl-C61-butyric acid methyl ester), in a representative series of organic solvent media (i.e., chloroform, toluene, chlorobenzene, 1,3-dichlorobenzene, and 1,2-dichlorobenzene), we show that a single time constant characterizing the dynamic stability of a tiny (angstrom-sized) solvation shell encompassing the fullerene particle can be utilized to effectively capture the known trends of fullerene solubility as reported in the literature. The underlying physics differs substantially between the two fullerene species, however. Although C60 was previously shown to be dictated by a diffusion-limited aggregation mechanism, the side-chain-substituted PCBM is demonstrated herein to proceed with an analogous reaction-limited aggregation with the "reaction rate" set by the fullerene rotational diffusivity in the medium. The present results suggest that dynamic quantities-in contrast to the more often employed, static ones-may provide an excellent means to characterize the complex (entropic and enthalpic) interplay between fullerene species and the solvent medium, shed light on the factors determining the solvent quality of a nanoparticle solution, and, in particular, offer a practical pathway to foreseeing optimum fullerene design and fullerene-solvent interactions. PMID:26488132

  11. Preparation and characterisation of the C 60 charge transfer complex C 60-.[1,1',3,3'-tetramethyl-Δ 2,2'-bi(imidazolidine)] +.

    NASA Astrophysics Data System (ADS)

    Schilder, A.; Gotschy, B.; Seidl, A.; Gompper, R.

    1995-04-01

    Ferromagnetism in the C 60 charge transfer salt C 60-.[1,1',3,3'-tetramethyl-Δ 2,2'-bi(imidazolidine)] +. (C 60[TMBI]) with Curie temperatures Tc above 140 K and coercive forces Hc of about 1000 Oe were reported by Wang and Zhu (J. Phys. Chem. Solids 55 (1994) 437). This dramatic increase of Tc and Hc by a small variation of the counterion compared to the first C 60 ferromagnet C 60-.[tetrakis(dimethylamino)ethylene] +. (Allemand et al., Science 253 (1991) 301) triggered us to elucidate the charge transfer from TMBI to C 60 by absorption measurements in the VIS/NIR. We found that the reaction kinetics is much more complex than in C 60[TDAE]. Solid state investigations of C 60[TMBI] with EPR and microwave conductivity are in clear disagreement with the results published by Wang and Zhu. We found instead strong evidence that C 60[TMBI] is rather a diamagnetic C 60 CT complex with a lot of structural defects than a high temperature molecular ferromagnet.

  12. Multiscale Simulation and Modeling of Multilayer Heteroepitactic Growth of C60 on Pentacene.

    PubMed

    Acevedo, Yaset M; Cantrell, Rebecca A; Berard, Philip G; Koch, Donald L; Clancy, Paulette

    2016-03-29

    We apply multiscale methods to describe the strained growth of multiple layers of C60 on a thin film of pentacene. We study this growth in the presence of a monolayer pentacene step to compare our simulations to recent experimental studies by Breuer and Witte of submonolayer growth in the presence of monolayer steps. The molecular-level details of this organic semiconductor interface have ramifications on the macroscale structural and electronic behavior of this system and allow us to describe several unexplained experimental observations for this system. The growth of a C60 thin film on a pentacene surface is complicated by the differing crystal habits of the two component species, leading to heteroepitactical growth. In order to probe this growth, we use three computational methods that offer different approaches to coarse-graining the system and differing degrees of computational efficiency. We present a new, efficient reaction-diffusion continuum model for 2D systems whose results compare well with mesoscale kinetic Monte Carlo (KMC) results for submonolayer growth. KMC extends our ability to simulate multiple layers but requires a library of predefined rates for event transitions. Coarse-grained molecular dynamics (CGMD) circumvents KMC's need for predefined lattices, allowing defects and grain boundaries to provide a more realistic thin film morphology. For multilayer growth, in this particularly suitable candidate for coarse-graining, CGMD is a preferable approach to KMC. Combining the results from these three methods, we show that the lattice strain induced by heteroepitactical growth promotes 3D growth and the creation of defects in the first monolayer. The CGMD results are consistent with experimental results on the same system by Conrad et al. and by Breuer and Witte in which C60 aggregates change from a 2D structure at low temperature to 3D clusters along the pentacene step edges at higher temperatures. PMID:26937559

  13. C60 fullerene localization and membrane interactions in RAW 264.7 immortalized mouse macrophages.

    PubMed

    Russ, K A; Elvati, P; Parsonage, T L; Dews, A; Jarvis, J A; Ray, M; Schneider, B; Smith, P J S; Williamson, P T F; Violi, A; Philbert, M A

    2016-02-21

    There continues to be a significant increase in the number and complexity of hydrophobic nanomaterials that are engineered for a variety of commercial purposes making human exposure a significant health concern. This study uses a combination of biophysical, biochemical and computational methods to probe potential mechanisms for uptake of C60 nanoparticles into various compartments of living immune cells. Cultures of RAW 264.7 immortalized murine macrophage were used as a canonical model of immune-competent cells that are likely to provide the first line of defense following inhalation. Modes of entry studied were endocytosis/pinocytosis and passive permeation of cellular membranes. The evidence suggests marginal uptake of C60 clusters is achieved through endocytosis/pinocytosis, and that passive diffusion into membranes provides a significant source of biologically-available nanomaterial. Computational modeling of both a single molecule and a small cluster of fullerenes predicts that low concentrations of fullerenes enter the membrane individually and produce limited perturbation; however, at higher concentrations the clusters in the membrane causes deformation of the membrane. These findings are bolstered by nuclear magnetic resonance (NMR) of model membranes that reveal deformation of the cell membrane upon exposure to high concentrations of fullerenes. The atomistic and NMR models fail to explain escape of the particle out of biological membranes, but are limited to idealized systems that do not completely recapitulate the complexity of cell membranes. The surprising contribution of passive modes of cellular entry provides new avenues for toxicological research that go beyond the pharmacological inhibition of bulk transport systems such as pinocytosis. PMID:26866469

  14. COLLISION DYNAMICS OF X@C60(X = He, Ne, Ar) AT LOW ENERGIES

    NASA Astrophysics Data System (ADS)

    Zhao, Qiang; Zhang, Feng-Shou; Zhou, Hong-Yu

    2013-12-01

    In this paper, a semi-empirical molecular dynamics model is developed. The central collisions of C60 + C60 and X@C60 + X@C60 (X = He, Ne, Ar) at various incident energy are investigated within this model. The fullerene dimers like a "dumbbell" can be formed by a self-assembly of C60 fullerene and X@C60 (X = He, Ne) endohedral fullerenes, and the new fullerene structure like "peanut" can be formed by a self-assembly of Ar@C60. It is found that Ar atom plays a great role in the collision of Ar@C60 + Ar@C60 because of its size effect. The energy effect is found that various incident energies cannot change the final structure at low energies if they are below a certain energy.

  15. Review of the progress in model theoretical studies of e + A @C60 electron scattering

    NASA Astrophysics Data System (ADS)

    Dolmatov, V.; Amusia, M.; Chernysheva, L.

    2016-05-01

    A series of recent semi-empirical theoretical studies of electron scattering off endohedral atoms A@ C60 have identified interesting measurements as well as more rigorous calculations of e + A @C60 scattering to perform. This report provides the interested researchers with a review of the most significant findings of works on e + A @C60 scattering. First, we demonstrate features of e + A @C60 elastic scattering of slow electrons and low-frequency bremsstrahlung when both the atom A and the cage C60 are ``frozen''. Then, we ``unfrozen'' the atom A but keep the C60 cage ``frozen'' and demonstrate novel effects of dynamical polarization of the atom A under the ``frozen'' C60 confinement on e + A @C60 scattering. Finally, we demonstrate the combined effect of both the dynamical polarization of the encapsulated atom and the static polarization of C60 on the scattering process. Supported by the NSF grant PHY-1305085.

  16. Prediction of superalkali@C60 endofullerenes, their enhanced stability and interesting properties

    NASA Astrophysics Data System (ADS)

    Srivastava, Ambrish Kumar; Pandey, Sarvesh Kumar; Misra, Neeraj

    2016-07-01

    We introduce a new kind of endofullerenes by trapping superalkali (SA) species (the species possessing lower ionization energy than alkali metals) into C60. Employing density functional theory, we show that all SA@C60 are stable for SA = FLi2, OLi3 and NLi4. The DOS curves and HOMO-LUMO gaps of SA@C60 closely resemble those of Li@C60. The charge transfer from SA to C60 is larger than that of Li to C60 and consequently, the mean polarizability of SA@C60 and its depression increase. We, therefore, believe that SA@C60 endofullerenes might attract further attention for their possible applications, analogous to alkali metal doped C60.

  17. Variation of excited-state dynamics in trifluoromethyl functionalized C60 fullerenes.

    PubMed

    Park, Jaehong; Ramirez, Jessica J; Clikeman, Tyler T; Larson, Bryon W; Boltalina, Olga V; Strauss, Steven H; Rumbles, Garry

    2016-08-17

    We report on electronically excited-state dynamics of three different trifluoromethyl C60 fullerenes (TMFs, C60(CF3)n: C60/4-1, C60/6-2, and C60/10-1, featuring four, six, and ten trifluoromethyl groups, respectively) using steady-state and time-resolved optical spectroscopy as well as ultrafast pump/probe transient absorption spectroscopy. C60/4-1 and C60/6-2 dissolved in toluene solvent show near-unity S1 → T1 intersystem crossing quantum yield (ΦISC), ca. 1 ns S1-state lifetimes, and microsecond-timescale T1-state lifetimes, which are typical of the fullerene class. On the other hand, C60/10-1 exhibits a dominant sub-nanosecond nonradiative S1 → S0 relaxation mechanism and negligible ΦISC, therefore decreasing the average excited-state lifetime (τavg) by about 5 orders of magnitude compared to that of C60/4-1 and C60/6-2 (τavg ≈ 17 μs and 54 μs for C60/4-1 and C60/6-2, respectively, whereas τavg ≈ 100 ps for C60/10-1). These excited-state characteristics of C60/4-1 and C60/6-2 are preserved in polymer matrix, suggesting that fullerene/polymer interactions do not modulate intrinsic photophysics of trifluoromethyl-substituted fullerenes. The contrasting excited-state study results of C60/4-1 and C60/6-2 to that of C60/10-1 infer that intrinsic optical properties and excited-state dynamics can be affected by the substitution on the fullerene. PMID:27485768

  18. Fullerene ion (C 60+) damage in Si at 25°C

    NASA Astrophysics Data System (ADS)

    Shen, Hao; Brink, C.; Hvelplund, P.; Shiryaev, S.; Shi, PeiXiong; Davies, J. A.

    1997-07-01

    A series of low-dose (< 5 × 10 12 ions cm -2) fullerene ion implantations in silicon has been carried out at 25°C over the energy range 100-530 keV. The resulting damage was measured quantitatively by Rutherford backscattering (RBS), using 2.0 MeV helium ions. This is an extension of an earlier study [J.B. Mitchell, J.A. Davies, L.M. Howe, R.S. Walker, K.B. Winterbon, G. Foti and J.A. Moore, Proc. 4th Intl. Conf. on Ion Implantation in Semiconductors, (Plenum Press, New York, 1975), p. 493.] of cluster-ion damage in Si where we had observed a 15-fold increase in damage-creation efficiency — i.e., the number of displaced Si atoms per keV of deposited energy — in going from (8.8 keV) monatomic carbon to (53 keV) C 6+. Using the same 8.8 keV per carbon, we find that a 530 keV fullerene (C 60+) ion displaces 100 times more Si atoms than a 53 keV C 6+ ion; thus C 60+ exhibits an additional 10-fold increase in damage creation efficiency compared to C 6+. At 100 keV, the deposited (nuclear) energy density θ within the central core of each C 60+ cascade (˜ 1.5 ev per Si atom) is considerably larger than the Si heat of melting. Not surprisingly, the observed number of displaced Si atoms also exceeds the theoretical cascade volume, thus providing strong evidence for some sort of spike effect. Despite the high damage levels involved, scanning tunneling microscopy revealed no evidence of any anomalous surface structures or craters. Comparison of the present C 60+ data with earlier Si implantation studies, where a variety of ions (C, Ga, As, Sb, Te, Bi) and energies (10-60 keV) had been used, confirms the previous suggestion that room temperature damage in Si is governed mainly by the cascade energy density θ (eV/atom).

  19. Geochemistry and cosmochemistry of fullerenes 3: Reaction of C60 and C70 with ozone

    NASA Technical Reports Server (NTRS)

    Heymann, D.; Chibante, L. P. F.

    1993-01-01

    C60 and C70 dissolved in toluene were treated with O2 gas containing 2.6 volume percent ozone and with O3-free oxygen. No reaction products were detected for 0.1 mole of O2 passed through the solution, but destruction of C60 was clearly detectable for a dose of 10(exp -6) moles of O3. C70 was destroyed more slowly than C60. Among the substances remaining in solution, we identified C60O, C70O, C60O2, C60O3, and C60O4. C60 crystals exposed to O3 at room temperature became less soluble in toluene in a matter of days, but oxides were apparently not formed.

  20. Contaminant-mobilizing capability of fullerene nanoparticles (nC60): Effect of solvent-exchange process in nC60 formation.

    PubMed

    Wang, Lilin; Fortner, John D; Hou, Lei; Zhang, Chengdong; Kan, Amy T; Tomson, Mason B; Chen, Wei

    2013-02-01

    Fullerene nanoparticles (nC(60)) in aqueous environments can significantly enhance the transport of hydrophobic organic contaminants by serving as a contaminant carrier. In the present study, the authors examine the effect of the solvent-exchange process on nC(60) aggregate formation and, subsequently, on nC(60) 's contaminant-mobilizing capability. A series of nC(60) samples were prepared using a modified toluene-water solvent-exchange method through the inclusion of a secondary organic solvent in the phase transfer of molecular C(60) in toluene to nC(60) in water. Two groups of solvents--a water-miscible group and a non-water-miscible group-of varied polarity were selected as secondary solvents. The involvement of a secondary solvent in the phase transfer process had only small effects on the particle size and distribution, ζ potential, and mobility of the nC(60) products but significantly influenced the capability of nC(60) to enhance the transport of 2,2',5,5'-polychlorinated biphenyl (PCB) in a saturated sandy soil column, regardless of whether the secondary solvent was water-miscible or non-water-miscible. The two groups of secondary solvents appear to affect the aggregation properties of nC(60) in water via different mechanisms. In general, nC(60) products made with a secondary water-miscible solvent have stronger capabilities to enhance PCB transport. Taken together, the results indicate that according to formation conditions and solvent constituents, nC(60) will vary significantly in its interactions with organic contaminants, specifically as related to adsorption or desorption as well as transport in porous media. PMID:23172734

  1. STM imagery and density functional calculations of C60 fullerene adsorption on the 6H-SiC(0001)-3×3 surface

    NASA Astrophysics Data System (ADS)

    Ovramenko, T.; Spillebout, F.; Bocquet, F. C.; Mayne, A. J.; Dujardin, G.; Sonnet, Ph.; Stauffer, L.; Ksari, Y.; Themlin, J.-M.

    2013-04-01

    Scanning tunneling microscopy (STM) studies of the fullerene C60 molecule adsorbed on the silicon carbide SiC(0001)-3×3 surface, combined with density functional theory (DFT) calculations, show that chemisorption of individual C60 molecules occurs through the formation of one bond to one silicon adatom only in contrast to multiple bond formation on other semiconducting surfaces. We observe three stable adsorption sites with respect to the Si adatoms of the surface unit cell. Comprehensive DFT calculations give different adsorption energies for the three most abundant sites showing that van der Waals forces between the C60 molecule and the neighboring surface atoms need to be considered. The C60 molecules are observed to form small clusters even at low coverage indicating the presence of a mobile molecular precursor state and nonnegligible intermolecular interactions.

  2. Assessment Of C60 As A Propellant Material For Ion Thrusters

    NASA Technical Reports Server (NTRS)

    Rapp, Don; Leifer, Stephanie D.

    1995-01-01

    Report presents analyses and data to support proposed use of C60 (buckminsterfullerene) as alternative to Xe, current propellent material of choice for use in ion thrusters. Concept of using C60 for this purpose described in "Electrostatic Propulsion Using C60 Molecules" (NPO-18526).

  3. C60 molecules grown on a Si-supported nanoporous supramolecular network: a DFT study.

    PubMed

    Boukari, Khaoula; Duverger, Eric; Stephan, Régis; Hanf, Marie-Christine; Sonnet, Philippe

    2014-07-28

    C60 fullerene assemblies on surfaces have attracted considerable attention because of their remarkable electronic properties. Now because of the competition between the molecules-substrate and the molecule-molecule interactions, an ordered C60 array is rather difficult to obtain on silicon surfaces. Here we present density functional theory simulations on C60 molecules deposited on a TBB (1,3,5-tri(1'-bromophenyl)benzene) monolayer lying on the Si(111)-boron surface (denoted SiB). The C60 molecules are located in the nanopores formed by the TBB network. Adsorption energy calculations show that the SiB surface governs the C60 vertical position, whereas the TBB network imposes the C60 lateral position, and stabilizes the molecule as well. The low charge density between the C60 and the SiB substrate on one hand, and on the other hand between the C60 and the TBB molecules, indicates that no covalent bond is formed between the C60 and its environment. However, according to charge density differences, a drastic charge reorganisation takes place between the Si adatoms and the C60 molecule, but also between the C60 and the surrounding TBB molecules. Finally, calculations show that a C60 array sandwiched between two TBB molecular layers is stable, which opens up the way to the growth of 3D supramolecular networks. PMID:24920165

  4. Electronic transitions and band offsets in C60:SubPc and C60:MgPc on MoO3 studied by modulated surface photovoltage spectroscopy

    NASA Astrophysics Data System (ADS)

    Fengler, S.; Dittrich, Th.; Rusu, M.

    2015-07-01

    Electronic transitions at interfaces between MoO3 layers and organic layers of C60, SubPc, MgPc, and nano-composite layers of SubPc:C60 and MgPc:C60 have been studied by modulated surface photovoltage (SPV) spectroscopy. For all systems, time dependent and modulated SPV signals pointed to dissociation of excitons at the MoO3/organic layer interfaces with a separation of holes towards MoO3. The highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps (EHL) of C60, SubPc, and MgPc and the effective EHL of SubPc:C60 and MgPc:C60 were measured. The offsets between the LUMO (ΔEL) or HOMO (ΔEH) bands were obtained with high precision and amounted to 0.33 or 0.73 eV for SubPc:C60, respectively, and to -0.33 or 0.67 eV for MgPc:C60, respectively. Exponential tails below EHL and most pronounced sub-bandgap transitions were characterized and ascribed to disorder and transitions from HOMO bands to unoccupied defect states.

  5. Molecular-dynamics simulations of energetic C60 impacts on (2×1)-(100) silicon

    NASA Astrophysics Data System (ADS)

    Hu, Xiaoyuan; Albe, Karsten; Averback, Robert S.

    2000-07-01

    Single impacts of energetic C60 clusters on (2×1)-(100) silicon substrates are studied by molecular-dynamics simulations. The role of impact energies and internal cluster energy are investigated in detail. Six different energy regimes can be identified at the end of the ballistic phase: At thermal energies below 20 eV the fullerene cages undergo elastic deformation, while impinging on the surface, and are mostly chemisorpted on top of the (2×1)-dimer rows. Between 20 and 100 eV the cage structure is preserved after the collision, but the cluster comes to rest within a few monolayers of the silicon surface. At energies of 100-500 eV the cluster partially decomposes and small coherent carbon caps are embedded in the surface. At higher energies up to 1.5 keV complete decomposition of the fullerene cluster occurs and an amorphous zone is formed in the subsurface area. At energies greater than approximately 1.5 keV craters form and above 6 keV sputtering becomes significant. In all cases the substrate temperature is of minor influence on the final result, but the projectile temperature is important for impacts at lower energies (<1.5 keV). For high energy impacts the ballistics resemble that of single atom impacts. Nearly 1:1 stoichiometry is obtained for impact energies around 1 keV. These results reveal an interesting possibility for controlled implantation of C in Si at high local concentrations, which might allow the formation of silicon carbide.

  6. Spatially mapping the spectral density of a single C60 molecule

    SciTech Connect

    Lu, Xinghua; Grobis, M.; Khoo, K.H.; Louie, Steve G.; Crommie, M.F.

    2002-07-01

    We have used scanning tunneling spectroscopy to spatially map the energy-resolved local density of states of individual C60 molecules on the Ag(100) surface. Spectral maps were obtained for molecular states derived from the C60 HOMO, LUMO, and LUMO + 1 orbitals, revealing new details of the spatially inhomogeneous C60 local electronic structure. Spatial inhomogeneities are explained using ab initio pseudopotential density functional calculations. These calculations emphasize the need for explicitly including the C60-Ag interaction and STM tip trajectory to understand the observed C60 local electronic structure.

  7. Oxidative stress-mediated hemolytic activity of solvent exchange-prepared fullerene (C60) nanoparticles

    NASA Astrophysics Data System (ADS)

    Trpkovic, Andreja; Todorovic-Markovic, Biljana; Kleut, Duska; Misirkic, Maja; Janjetovic, Kristina; Vucicevic, Ljubica; Pantovic, Aleksandar; Jovanovic, Svetlana; Dramicanin, Miroslav; Markovic, Zoran; Trajkovic, Vladimir

    2010-09-01

    The present study investigated the hemolytic properties of fullerene (C60) nanoparticles prepared by solvent exchange using tetrahydrofuran (nC60THF), or by mechanochemically assisted complexation with macrocyclic oligosaccharide gamma-cyclodextrin (nC60CDX) or the copolymer ethylene vinyl acetate-ethylene vinyl versatate (nC60EVA-EVV). The spectrophotometrical analysis of hemoglobin release revealed that only nC60THF, but not nC60CDX or nC60EVA-EVV, was able to cause lysis of human erythrocytes in a dose- and time-dependent manner. Atomic force microscopy revealed that nC60THF-mediated hemolysis was preceded by erythrocyte shrinkage and increase in cell surface roughness. A flow cytometric analysis confirmed a decrease in erythrocyte size and demonstrated a significant increase in reactive oxygen species production in red blood cells exposed to nC60THF. The nC60THF-triggered hemolytic activity was efficiently reduced by the antioxidants N-acetylcysteine and butylated hydroxyanisole, as well as by serum albumin, the most abundant protein in human blood plasma. These data indicate that nC60THF can cause serum albumin-preventable hemolysis through oxidative stress-mediated damage of the erythrocyte membrane.

  8. Structural and magnetic properties of Co films on highly textured and randomly oriented C60 layers

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Ok; Choi, Jun Woo; Lee, Dong Ryeol

    2016-03-01

    The structural and magnetic properties of Co/C60/pentacene and Co/C60 thin film structures were investigated. Atomic force microscopy and x-ray reflectivity analysis show that the presence or absence of a pentacene buffer layer leads to a highly textured or randomly oriented C60 layer, respectively. A Co film deposited on a randomly oriented C60 layer penetrates into the C60 layer when it is deposited at a slow deposition rate. The Co penetration can be minimized, regardless of the Co deposition rate, by growth on a highly textured and nanostructured C60/pentacene layer. Vibrating sample magnetometry measurements show that the saturation magnetization of Co/C60/pentacene is significantly reduced compared to that of Co/C60. On the other hand, the Co penetration does not seem to have an effect on the magnetic properties, suggesting that the structural properties of the Co and C60 layer, rather than the Co penetration into the organic C60 layer, are critical to the magnetic properties of the Co/C60.

  9. Photocorrosion inhibition and enhancement of photocatalytic activity for ZnO via hybridization with C60.

    PubMed

    Fu, Hongbo; Xu, Tongguang; Zhu, Shengbao; Zhu, Yongfa

    2008-11-01

    C60 molecules with monomolecular layer state dispersed on the surface of ZnO and formed the hybridized interaction between ZnO and C60. C60-hybridized ZnO photocatalyst showed enhanced photocatalytic activity for the degradation of the organic dye and the photocorrosion of ZnO was successfully inhibited bythe hybridization of C60 molecules. The photocorrosion inhibition of ZnO by C60 molecule could be attributed to the reduced activation of surface oxygen atom. The enhanced photocatalytic activity for C60-hybridized ZnO was originated from the high migration efficiency of photoinduced electrons on the interface of C60 and ZnO, which was produced by the interaction of C60 and ZnO with a conjugative pi-system. The enhancement degree of photocatalytic activity was strongly depended on the coverage of C60 molecules on the surface of ZnO nanoparticles, and the optimum hybridization effect was found at a weight ratio of 1.5% (C60/ZnO). The hybridization of C60 with semiconductors could be used to improve the photocatalytic activity as well as the photostability. PMID:19031903

  10. Radical reactions of C 60Ph 5Cl: EPR study and DFT calculations

    NASA Astrophysics Data System (ADS)

    Kalina, O. G.; Tumanskii, B. L.; Chistyakov, A. L.; Stankevich, I. V.; Birkett, P. R.; Taylor, R.

    2003-10-01

    UV-irradiation of a toluene solution of C 60Ph 5Cl leads to the formation of the stable rad C 60Ph 5 cyclopentadienyl-type fullerenyl radical. Under UV-irradiation of a toluene solution of C 60Ph 5Cl containing Hg[P(O)(OPr i) 2] 2 (Pr i=CH(CH 3) 2), three isomers of the adducts of phosphoryl radicals with C 60Ph 5Cl are formed. Density functional (DFT) approach with the B3LYP functional was used for estimating of the enthalpies of the formation and hyperfine coupling constants for all possible adducts of phosphoryl radicals with C 60Ph 5Cl. Biradical particles rad C 60Ph 5[P(O)(OPr i) 2]- rad C 60Ph 5[P(O)(OPr i) 2] with a distance between unpaired electrons of about 10.5 Å, are also obtained.

  11. On observing C60+ and C602+ in laboratory and space

    NASA Astrophysics Data System (ADS)

    Strelnikov, D.; Kern, B.; Kappes, M. M.

    2015-12-01

    Recently, we have measured the IR absorptions of C60+, C60-, and C602+ in neon matrixes. Many previously unknown absorptions were established. Here we compare our laboratory IR absorption spectra for C60+ and C602+ to the IR emission spectra of several astronomical objects that show C60 emission. We find that IR bands of C60+ are possibly present in the objects Tc1, SMP SMC 16, NGC 7023, NGC 2244, and SMP LMC 02. Infrared emission features possibly due to C602+ were identified in NGC 7023. To help with future observations of fullerene-related DIBs, we also revisited the oscillator strengths of the NIR absorptions of C60+, and report significantly revised values. Additionally, we report the UV oscillator strengths of C60+.

  12. Synthesis of poly(vinyl alcohol)/C(60) and poly(N-vinylpyrrolidone)/C(60) nanohybrids as potential photodynamic cancer therapy agents.

    PubMed

    Hurtgen, Marie; Debuigne, Antoine; Mouithys-Mickalad, Ange; Jérôme, Robert; Jérôme, Christine; Detrembleur, Christophe

    2010-04-01

    Well-defined poly(vinyl acetate) (PVAc) and poly(N-vinylpyrrolidone)-co-poly(vinyl acetate) (PNVP-co-PVAc) chains end-capped by Co(acac)(2) (acac=acetylacetonate) and prepared by cobalt-mediated radical polymerization (CMRP) are grafted onto a fullerene. Homolytic Co-C bond cleavage of the polymer chain ends at 30 degrees C releases the polymeric radicals that add onto C(60), thereby leading to the corresponding PVAc/C(60) and PNVP-co-PVAc/C(60) nanohybrids. The [polymer-Co(acac)(2)]/[C(60)] molar ratio was varied to adjust the structure of the nanohybrids, and more particularly the number of grafted arms. Finally, the potential of the hydrosoluble PVOH/C(60) nanohybrids, which result from the methanolysis of the ester groups of PVAc/C(60), and of the PNVP-co-PVAc/C(60) nanohybrids as photosensitizers for photodynamic therapy (PDT), was approached. First, photobleaching tests demonstrated the ability of these nanohybrids to produce singlet oxygen upon irradiation, which can play a role in cell damage. Second, cell viability assays demonstrated that both types of nanohybrids are deprived of intrinsic cytotoxicity in the dark, whereas they promoted significant cell mortality when subjected to light treatment. The selective response of these materials to irradiation makes them promising compounds for PDT. PMID:20140908

  13. Hierarchical aqueous self-assembly of C60 nano-whiskers and C60-silver nano-hybrids under continuous flow.

    PubMed

    Iyer, K Swaminathan; Raston, Colin L; Saunders, Martin

    2007-09-01

    The ubiquitous starch-iodine complex can be used to organize hydrophobic fullerene C(60) in water into nano-whiskers shrouded by the biopolymer, and are approximately 5-8 nm in cross section, and 250-350 nm in length, as a hierarchical self assembly process. The preformed starch-iodine complex reacts with solid pristine C(60) affording nano-whiskers with iodine surrounding the fullerene array, the iodine then being removed on treatment with ascorbic acid. The hydrophobic surface of the nano-whiskers of C(60) can be coated with silver metal in a controlled way using 'soft energy' spinning disc processing. PMID:17713609

  14. Ortho-para conversion of endohedral water in the fullerene C60 at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Shugai, Anna; Nagel, U.; Rõõm, T.; Mamone, S.; Concistrè, M.; Meier, B.; Krachmalnicoff, A.; Whitby, R. J.; Levitt, M. H.; Lei, Xuegong; Li, Yongjun; Turro, N. J.

    2015-03-01

    Water displays the phenomenon of spin isomerism in which the two proton spins either couple to form a triplet (ortho water, I = 1) or a singlet nuclear spin state (para water, I = 0). Here we study the interconversion of para and ortho water. The exact mechanism of this process is still not fully understood. In order to minimize interactions between molecules we use a sample where a single H2O is trapped in the C60 molecular cage (H2O@C60)andH2O@C60iscrystallized.H2O@C60 has long-lived ortho state and ortho-para conversion kinetics is non-exponential at LHeT. We studied mixtures of H2O@C60, D2O@C60 and C60 using IR absorption, NMR and dielectric measurements. We saw the speeding up of the interconversion with the growth of H2O@C60 concentration in C60 or when D2O@C60 was added. At some temperatures the kinetics is exponential. Models are discussed in order to explain the T and concentration dependence of ortho-para interconversion kinetics. This work was supported by institutional research funding IUT23-3 of the Estonian Ministry of Education and Research.

  15. Photoinduced Charge Separation in the Carbon Nano-Onion C60@C240.

    PubMed

    Voityuk, Alexander A; Solà, Miquel

    2016-07-28

    The double-shell fullerene C60@C240 formed by inclusion of C60 into C240 is the smallest stable carbon nano-onion. In this article, we analyze in detail the character of the excited states of C60@C240 in terms of exciton localization and charge transfer between the inner and outer shells. The unique structure of the buckyonion leads to a large electrostatic stabilization of charge-separated (CS) states in the C60@C240. As a result, the CS states C60(+)@C240(-) lie in the same region of the electronic spectrum (2.4-2.6 eV) as strongly absorbing locally excited states and, therefore, can be effectively populated. The CS states C60(-)@C240(+) are found to be 0.5 eV higher in energy than the CS states C60(+)@C240(-). Unlike the situation observed in donor-acceptor systems, the energies of the CS states in C60@C240 do not practically depend on the environment polarity. This leads to exceptionally small reorganization energies for electron transfer between the shells. Electronic couplings for photoinduced charge-separation and charge-recombination processes are calculated. The absolute rate of the formation of the CS state C60(+)@C240(-) is estimated at ∼4 ps(-1). The electronic features found in C60@C240 are likely to be shared by other carbon nano-onions. PMID:27383921

  16. Vibrational Cooling in A Cold Ion Trap: Vibrationally Resolved Photoelectron Spectroscopy of Cold C60- Anions

    SciTech Connect

    Wang, Xue B.; Woo, Hin-koon; Wang, Lai S.

    2005-08-01

    We demonstrate vibrational cooling of anions via collisions with a background gas in an ion trap attached to a cryogenically controlled cold head (10 ? 400 K). Photoelectron spectra of vibrationally cold C60- anions, produced by electrospray ionization and cooled in the cold ion trap, have been obtained. Relative to spectra taken at room temperature, vibrational hot bands are completely eliminated, yielding well resolved vibrational structures and a more accurate electron affinity for neutral C60. The electron affinity of C60 is measured to be 2.683 ? 0.008 eV. The cold spectra reveal complicated vibrational structures for the transition to the C60 ground state due to the Jahn-Teller effect in the ground state of C60-. Vibrational excitations in the two Ag modes and eight Hg modes are observed, providing ideal data to assess the vibronic couplings in C60-.

  17. Study of the interaction of C60 fullerene with human serum albumin in aqueous solution

    SciTech Connect

    Li, Song; Zhao, Xiongce; Mo, Yiming; Cummings, Peter T; Heller, William T

    2013-01-01

    Concern about the toxicity of engineered nanoparticles, such as the prototypical nanomaterial C60 fullerene, continues to grow. While evidence continues to mount that C60 and its derivatives may pose health hazards, the specific molecular interactions of these particles with biological macromolecules require further investigation. To better understand the interaction of C60 with proteins, the protein human serum albumin (HSA) was studied in solution with C60 at C60:HSA molar ratios ranging from 1:2 to 4:1. HSA is the major protein component of blood plasma and plays a role in a variety of functions, such as the maintenance of blood pH and pressure. The C60-HSA interaction was probed by a combination of circular dichroism (CD) spectroscopy, small-angle neutron scattering (SANS) and atomistic molecular dynamics (MD) simulations to understand C60-driven changes in the structure of HSA in solution. The CD spectroscopy demonstrates that the secondary structure of the protein decreases in -helical content in response to the presence of C60. Similarly, C60 produces subtle changes in the solution conformation of HSA, as evidenced by the SANS data and MD. The data do not indicate that C60 is causing a change in the oligomerization state of the protein. Taken together results demonstrate that C60 interacts with HSA, but it does not strongly perturb the structure of the protein by unfolding it or inducing aggregation, suggesting a mechanism for transporting C60 throughout the body to accumulate in various tissues.

  18. A Novel Matrix for Immobilizing Protein: Supported Hybrid Nano C60-Lipid Membrane.

    PubMed

    He, Lulu; Yue, Qiulin; Zhang, Lele; Zhang, Xin

    2016-06-01

    Supported hybrid nano C60-lipid membrane based on cysteamine monolayer was made on gold electrode. Hemoglobin (Hb) could be immobilized in the membrane firmly because the membrane can supply a biological environment for Hb. The electrochemical behavior of Hb in the membrane was investigated by cyclic voltammetry. As a good electron mediator, C60 could make the electron transfer of the protein in hybrid C60-lipid membrane more accessible. PMID:27427649

  19. Hybridization-Induced Carrier Localization at the C60 /ZnO Interface.

    PubMed

    Kelly, Leah L; Racke, David A; Kim, Hyungchul; Ndione, Paul; Sigdel, Ajaya K; Berry, Joseph J; Graham, Samuel; Nordlund, Dennis; Monti, Oliver L A

    2016-05-01

    Electronic coupling and ground-state charge transfer at the C60 /ZnO hybrid interface is shown to localize carriers in the C60 phase. This effect, revealed by resonant X-ray photoemission, arises from interfacial hybridization between C60 and ZnO. Such localization at carrier-selective electrodes and interlayers may lead to severely reduced carrier harvesting efficiencies and increased recombination rates in organic electronic devices. PMID:26596518

  20. Preparation and structure of the alkali-metal fulleride A4C60

    NASA Astrophysics Data System (ADS)

    Fleming, R. M.; Rosseinsky, M. J.; Ramirez, A. P.; Murphy, D. W.; Tully, J. C.; Haddon, R. C.; Siegrist, T.; Tycko, R.; Glarum, S. H.; Marsh, P.; Dabbagh, G.; Zahurak, S. M.; Makhija, A. V.; Hampton, C.

    1991-08-01

    SUPERCONDUCTING K3C60 (ref. 1) has been shown2 to have an intercalated face-centred cubic (f.c.c.) structure, and other A3C60 compounds (where A is K, Rb or mixtures of K, Rb and/or Cs) form an isostructural series with superconducting transition temperatures up to 31.3 K (ref. 3). Recently we reported4 13C NMR studies of K x C60 for x<3, and concluded that the system contained two phases (x = 0 and x = 3) for 0C60 in the range 3C60 (refs 2, 3) and body-centred cubic A6C60 (ref. 5), A4C60 (where A is K, Rb, Cs) has a body-centred tetragonal structure. We show that all of the experimentally observed phases of A x C60 can be predicted solely on the basis of electrostatic considerations. We have found no evidence for superconductivity in A4C60.

  1. Transport properties of the H2O@C60-dimer-based junction.

    PubMed

    Zhu, Chengbo; Wang, Xiaolin

    2015-09-23

    Theoretical predictions play an important role in finding potential applications in molecular electronics. Fullerenes have a number of potential applications, and the charge flow from a single C60 molecule to another becomes more versatile and more interesting after doping. Here, we report the conductance of two H2O@C60 molecules in series order and how the number of encapsulated water molecules influences the transport properties of the junction. Encapsulating an H2O molecule into one of the C60 cages increases the conductance of the dimer. Negative differential resistance is found in the dimer systems, and its peak-to-valley current ratio depends on the number of encapsulated H2O molecules. The conductance of the C60 dimer and the H2O@C60 dimer is two orders of magnitude smaller than that of the C60 monomer. Furthermore, we demonstrate that the conductance of the molecular junctions based on the H2O@C60 dimer can be tuned by moving the encapsulated H2O molecules. The conductance is H2O-position dependent. Our findings indicate that H2O@C60 can be used as a building block in C60-based molecular electronic devices and sensors. PMID:26325223

  2. Transport properties of the H2O@C60-dimer-based junction

    NASA Astrophysics Data System (ADS)

    Zhu, Chengbo; Wang, Xiaolin

    2015-09-01

    Theoretical predictions play an important role in finding potential applications in molecular electronics. Fullerenes have a number of potential applications, and the charge flow from a single C60 molecule to another becomes more versatile and more interesting after doping. Here, we report the conductance of two H2O@C60 molecules in series order and how the number of encapsulated water molecules influences the transport properties of the junction. Encapsulating an H2O molecule into one of the C60 cages increases the conductance of the dimer. Negative differential resistance is found in the dimer systems, and its peak-to-valley current ratio depends on the number of encapsulated H2O molecules. The conductance of the C60 dimer and the H2O@C60 dimer is two orders of magnitude smaller than that of the C60 monomer. Furthermore, we demonstrate that the conductance of the molecular junctions based on the H2O@C60 dimer can be tuned by moving the encapsulated H2O molecules. The conductance is H2O-position dependent. Our findings indicate that H2O@C60 can be used as a building block in C60-based molecular electronic devices and sensors.

  3. Electrochemically produced films and polycrystalline salts of C60n-: Their physical characterization

    SciTech Connect

    Jones, M.T.; Subramanian, R.; Boulas, P.

    1994-12-31

    The discovery of C60 and its anionic salts C60{sup n-} (n = 1, 2, or 3) has provided a series of new materials with a wide range of very interesting chemical and physical properties such as ferromagnetism, nonlinear optical activity, semiconductivity and superconductivity. To date, relatively few salts of the anions of C60 have been studied because until recently a simple synthesis procedure did not exist. The authors recently developed simple and efficient methods for preparing thin films (prepared electrochemically) of both C60 and C60n- (n = 1, 2, or 3) and for preparing anion salts of C60 (prepared electrochemically and chemically). The authors now report the spectroscopic characterization of some of these materials. For example, studies of the temperature dependence of the Raman spectra of selected films (such as C60 and Cs3C60) are discussed. Also discussed are the ESR studies of a series of polycrystalline C60 anion salts derived from films as well as from the facile chemical preparation methods which are presented. The results of these spectroscopic studies are discussed as are results from other physical methods of characterization.

  4. Solid-phase C60 in the peculiar binary XX Oph?

    NASA Astrophysics Data System (ADS)

    Evans, A.; van Loon, J. Th.; Woodward, C. E.; Gehrz, R. D.; Clayton, G. C.; Helton, L. A.; Rushton, M. T.; Eyres, S. P. S.; Krautter, J.; Starrfield, S.; Wagner, R. M.

    2012-03-01

    We present infrared spectra of the binary XX Oph obtained with the Infrared Spectrograph on the Spitzer Space Telescope. The data show some evidence for the presence of solid C60- the first detection of C60 in the solid phase - together with the well-known 'unidentified infrared' emission features. We suggest that, in the case of XX Oph, the C60 is located close to the hot component, and that in general it is preferentially excited by stars having effective temperatures in the range 15 000-30 000 K. C60 may be common in circumstellar environments, but unnoticed in the absence of a suitable exciting source.

  5. Behaviour of fullerenes (C60) in the terrestrial environment: potential release from biosolids-amended soils.

    PubMed

    Navarro, Divina A; Kookana, Rai S; Kirby, Jason K; Martin, Sheridan M; Shareef, Ali; Du, Jun; McLaughlin, Mike J

    2013-11-15

    Owing of their wide-range of commercial applications, fullerene (C60) nanoparticles, are likely to reach environments through the application of treated sludge (biosolids) from wastewater treatment plants to soils. We examined the release behaviour of C60 from contaminated biosolids added to soils with varying physicochemical characteristics. Incubation studies were carried out in the dark for up to 24 weeks, by adding biosolids spiked (1.5mg/kg) with three forms of C60 (suspended in water, in humic acid, and precipitated/particulate) to six contrasting soils. Leaching of different biosolids+soil systems showed that only small fractions of C60 (<5% of applied amount) were released, depending on incubation time and soil properties (particularly dissolved organic carbon content). Release of C60 from unamended soils was greater (at least twice as much) than from biosolids-amended soils. The form of C60 used to spike the biosolids had no significant effect on the release of C60 from the different systems. Contact time of C60 in these systems only slightly increased the apparent release up to 8 weeks, followed by a decrease to 24 weeks. Mass balance analysis at the completion of the experiment revealed that 20-60% of the initial C60 applied could not be accounted for in these systems; the reasons for this are discussed. PMID:24076573

  6. C60(Nd) nanoparticles enhance chemotherapeutic susceptibility of cancer cells by modulation of autophagy

    NASA Astrophysics Data System (ADS)

    Wei, Pengfei; Zhang, Li; Lu, Yang; Man, Na; Wen, Longping

    2010-12-01

    Autophagy, an evolutionally conserved intracellular process degrading cytoplasmic proteins and organelles for recycling, has become one of the most remarkable strategies applied in cancer research. The fullerene C60 nanoparticle (nC60) has been shown to induce autophagy and sensitize chemotherapeutic killing of cancer cells, but the details still remain unknown. Here we show that a water-dispersed nanoparticle solution of derivatized fullerene C60, C60(Nd) nanoparticles (nC60(Nd)), has greater potential in inducing autophagy and sensitizing chemotherapeutic killing of both normal and drug-resistant cancer cells than nC60 does in an autophagy-dependent fashion. Additionally we further demonstrated that autophagy induced by nC60/C60(Nd) and Rapamycin had completely different roles in cancer chemotherapy. Our results, for the first time, revealed a novel and more potent derivative of the C60 nanoparticle in enhancing the cytotoxicity of chemotherapeutic agents and reducing drug resistance through autophagy modulation, which may ultimately lead to novel therapeutic strategies in cancer therapy.

  7. Transparent conducting C60:LiF nanocomposite thin films for organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Zhao, Y. Q.; Huang, C. J.; Ogundimu, T.; Lu, Z. H.

    2007-09-01

    C60:LiF nanocomposite thin films were synthesized by physical vapor coevaporation. It is found that the nano-composite films are extremely conductive even at high LiF concentrations of up to 75wt% and that the films form Ohmic contacts with Al electrodes. IR measurements showed evidence of charge transfer from LiF to C60. Scanning electron microscope studies showed that C60:LiF (75wt%) nanocomposite forms uniform films. Compared with an archetypical tris(8-hydroxyquinolinato)alumina based device, OLEDs with the C60:LiF composite electron transport materials have lower driving voltages and higher power efficiencies.

  8. Fullerene C60 exposure elicits an oxidative stress response in embryonic zebrafish

    PubMed Central

    Usenko, Crystal Y.; Harper, Stacey L.; Tanguay, Robert L.

    2008-01-01

    Due to its unique physicochemical and optical properties, C60 has raised interest in commercialization for a variety of products. While several reports have determined this nanomaterial to act as a powerful antioxidant, many other studies have demonstrated a strong oxidative potential through photoactivation. To directly address the oxidative potential of C60, the effects of light and chemical supplementation and depletion of glutathione (GSH) on C60-induced toxicity were evaluated. Embryonic zebrafish were used as a model organism to examine the potential of C60 to elicit oxidative stress responses. Reduced light during C60 exposure significantly decreased mortality and the incidence of fin malformations and pericardial edema at 200 and 300 ppb C60. Embryos co-exposed to the glutathione precursor, N-acetylcysteine (NAC), also showed reduced mortality and pericardial edema; however, fin malformations were not reduced. Conversely, co-exposure to the GSH synthesis inhibitors, butathionine sulfoximine (BSO) and diethyl maleate (DEM), increased the sensitivity of zebrafish to C60 exposure. Co-exposure of C60 or its hydroxylated derivative, C60(OH)24, with H2O2 resulted in increased mortality along the concentration gradient of H2O2 for both materials. Microarrays were used to examine the effects of C60 on the global gene expression at two time points, 36 and 48 hours post fertilization (hpf). At both life stages there were alterations in the expression of several key stress response genes including glutathione-S-transferase, glutamate cysteine ligase, ferritin, α-tocopherol transport protein and heat shock protein 70. These results support the hypothesis that C60 induces oxidative stress in this model system. PMID:18299140

  9. Transport and retention of fullerene (C60) nanoparticles in natural soils

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Li, Y.; Abriola, L. M.; Pennell, K. D.

    2008-12-01

    Although several column studies have investigated the transport and deposition of fullerene (C60) nanoparticles in ideal porous media, such as washed quartz sands and glass beads, far less attention has been directed toward natural soils. To address this issue, a series of column experiments was performed to quantify the transport and retention of C60 nanoparticles in a borosilicate glass column (10 cm length x 2.5 cm dia.) packed with either Appling soil or Webster soil. Introduction of a C60 suspension containing 1 mM calcium chloride as background electrolyte for up to 65 pore volumes resulted in 100 percent retention of injected mass. Retained C60 nanoparticles were concentrated within 6 cm of the column from inlet, with solid phase concentrations approaching 130 μg/g. The presence of Suwannee River humic acid (20 mg/L) in the C60 suspension slightly enhanced mobility of nC60, although effluent breakthrough was not observed. However, when mixed with 1,000 mg/L polyethoxylate (20) sorbitan monooleate (Tween 80), C60 nanoparticles were readily transported through Appling soil, with less than 40 percent of injected mass retained. Retentions profiles of nC60 exhibited gradual ascent and descent, but not symmetrically, with distance from inlet. A mathematic transport model incorporating classical filtration theory, non-linear sorption process, and straining was utilized to capture C60 effluent breakthrough curves and retention profiles observed in the column experiments. These findings indicate that Appling soil and Webster soil exhibit large retention capacity for C60 nanoparticle, and that transport of C60 is greatly enhanced in the presence of stabilizing agents.

  10. Behavioral and physiological changes in Daphnia magna when exposed to nanoparticle suspensions (titanium dioxide, nano-C60, and C60HxC70Hx)

    PubMed Central

    Lovern, Sarah B.; Strickler, J. Rudi; Klaper, Rebecca

    2008-01-01

    Little is known about the impact manufactured nanoparticles will have on aquatic organisms. Previously, we demonstrated that toxicity differs with nanoparticle type and preparation and observed behavioral changes upon exposure to the more lethal nanoparticle suspensions. In this experiment, we quantified these behavioral and physiological responses of Daphnia at sublethal nanoparticle concentrations. Titanium dioxide (TiO2) and fullerenes (nano-C60) were chosen for their potential use in technology. Other studies suggest that addition of functional groups to particles can affect their toxicity to cell cultures, but it is unknown if the same is true at the whole organism level. Therefore, a fullerene derivative, C60HxC70Hx, was also used to examine how functional groups affect Daphnia response. Using a high-speed camera, we quantified several behavior and physiological parameters including hopping frequency, feeding appendage and postabdominal curling movement, and heart rate. Nano-C60 was the only suspension to cause a significant change in heart rate. Both exposure to nano-C60 and C60HxC70Hx suspensions caused hopping frequency and appendage movement to increase. These results are associated with increased risk of predation and reproductive decline. They indicate that certain nanoparticle types may have impacts on population and food web dynamics in aquatic systems. PMID:17626453

  11. Behavioral and physiological changes in Daphnia magna when exposed to nanoparticle suspensions (titanium dioxide, nano-C60, and C60HxC70Hx).

    PubMed

    Lovern, Sarah B; Strickler, J Rudi; Klaper, Rebecca

    2007-06-15

    Little is known aboutthe impact manufactured nanoparticles will have on aquatic organisms. Previously, we demonstrated that toxicity differs with nanoparticle type and preparation and observed behavioral changes upon exposure to the more lethal nanoparticle suspensions. In this experiment, we quantified these behavioral and physiological responses of Daphnia magna at sublethal nanoparticle concentrations. Titanium dioxide (TiO2) and fullerenes (nano-C60) were chosen for their potential use in technology. Other studies suggest that addition of functional groups to particles can affect their toxicity to cell cultures, but it is unknown if the same is true at the whole organism level. Therefore, a fullerene derivative, C60HxC70Hx, was also used to examine how functional groups affect Daphnia response. Using a high-speed camera, we quantified several behavior and physiological parameters including hopping frequency, feeding appendage and postabdominal curling movement, and heart rate. Nano-C60 was the only suspension to cause a significant change in heart rate. Exposure to both nano-C60 and C60HxC70Hx suspensions caused hopping frequency and appendage movement to increase. These results are associated with increased risk of predation and reproductive decline. They indicate that certain nanoparticle types may have impacts on population and food web dynamics in aquatic systems. PMID:17626453

  12. Molecular Depth Profiling of Buried Lipid Bilayers Using C60-SIMS

    PubMed Central

    Lu, Caiyan; Wucher, Andreas; Winograd, Nicholas

    2010-01-01

    An organic delta layer system made of alternating Langmuir Blodgett multilayers of barium arachidate (AA) and barium dimyristoyl phosphatidate (DMPA) was constructed to elucidate the factors that control depth resolution in molecular depth profile experiments. More specifically, one or several bilayers of DMPA (4.4 nm) were embedded in relatively thick (51 to 105 nm) multilayer stacks of AA, resulting in a well-defined delta-layer model system closely resembling a biological membrane. 3-D imaging ToF-SIMS depth profile analysis was performed on this system using a focused buckminsterfullerene (C60) cluster ion beam. The delta layer depth response function measured in these experiments exhibits similar features as those determined in inorganic depth profiling, namely an asymmetric shape with quasi-exponential leading and trailing edges and a central Gaussian peak. The effects of sample temperature, primary ion kinetic energy and incident angle on the depth resolution were investigated. While the information depth of the acquired SIMS spectra was found to be temperature independent, the depth resolution was found to be significantly improved at low temperature. Ion induced mixing is proposed to be largely responsible for the broadening, rather than topography, as determined by AFM, therefore depth resolution can be optimized using lower kinetic energy, glancing angle and liquid nitrogen temperature. PMID:21121691

  13. Electronic and optical properties of superhard nanocomposite films obtained from C60 ion beam

    NASA Astrophysics Data System (ADS)

    Pukha, V. E.; Karbovskii, V. L.; Rudchenko, S. O.; Drozdov, A. N.; Maleyev, M. V.; Starikov, V. V.; Pugachov, A. T.

    2014-09-01

    The study of electronic and transport properties of amorphous and nanocomposite superhard carbon films deposited from the mass-separated beam of accelerated C60 ions with an energy of 5 keV onto a substrate with temperatures (Ts) ranging from 373 K to 773 K is present. The films demonstrate a transition from the amorphous state with sp2 2D clusters to nanocomposite one with 3D graphite nanocrystals at Ts ˜ 573 K. That is accompanied by the registration of two phases with optical gaps of 3.6 eV and <1 eV. The narrow optical gap (<1 eV) is shown to attribute to the graphite nanocrystals, and a wide one (3.6 eV) to the amorphous diamond-like matrix. Measurement of the electrical conductivity of films at low temperatures showed a gradual transition at Ts increasing from hopping conductivity with variable length of jump in amorphous films to the tunnel one with power-law dependence from temperature for the nanocomposite and further to the percolation conductivity at direct contact of graphite nanocrystals. The role of intergranular insulator at tunneling conductivity of nanocomposite is played by amorphous carbon matrix which has an electronic structure close to amorphous diamond.

  14. Synthesis, Structure, and Properties of the Fullerene C60 Salt of Crystal Violet, (CV(+) )(C60 (.-) )⋅0.5 C6 H4 Cl2 , which Contained Closely Packed Zigzagged C60 (.-) Chains.

    PubMed

    Konarev, Dmitri V; Kuzmin, Alexey V; Khasanov, Salavat S; Ishikawa, Manabu; Otsuka, Akihiro; Yamochi, Hideki; Saito, Gunzi; Lyubovskaya, Rimma N

    2016-06-01

    The reduction of fullerene C60 by zinc dust in the presence of crystal violet cations (CV(+) ) yielded a deep-blue solution, from which crystals of (CV(+) )(C60 (.-) )⋅0.5 C6 H4 Cl2 (1) were obtained by slow mixing with n-hexane. The salt contained isolated, closely packed zigzagged chains that were composed of C60 (.-) radical anions with a uniform interfullerene center-to-center distance of 9.98 Å. In spite of the close proximity of the fullerenes, they did not dimerize, owing to spatial separation by the phenyl substituents of CV(+) . The room-temperature conductivity of compound 1 was 3×10(-2)  S cm(-1) along the fullerene chains. The salt exhibited semiconducting behavior, with an activation energy of Ea =167 meV. Spins localized on C60 (.-) were antiferromagnetically coupled within the fullerene chains, with a Weiss temperature of -19 K without long-range magnetic ordering down to 1.9 K. PMID:27062654

  15. Complex of C60 Fullerene with Doxorubicin as a Promising Agent in Antitumor Therapy

    NASA Astrophysics Data System (ADS)

    Prylutska, Svitlana V.; Skivka, Larysa M.; Didenko, Gennadiy V.; Prylutskyy, Yuriy I.; Evstigneev, Maxim P.; Potebnya, Grygoriy P.; Panchuk, Rostyslav R.; Stoika, Rostyslav S.; Ritter, Uwe; Scharff, Peter

    2015-12-01

    The main aim of this work was to evaluate the effect of doxorubicin in complex with C60 fullerene (C60 + Dox) on the growth and metastasis of Lewis lung carcinoma in mice and to perform a primary screening of the potential mechanisms of C60 + Dox complex action. We found that volume of tumor from mice treated with the C60 + Dox complex was 1.4 times less than that in control untreated animals. The number of metastatic foci in lungs of animals treated with C60 + Dox complex was two times less than that in control untreated animals. Western blot analysis of tumor lysates revealed a significant decrease in the level of heat-shock protein 70 in animals treated with C60 + Dox complex. Moreover, the treatment of tumor-bearing mice was accompanied by the increase of cytotoxic activity of immune cells. Thus, the potential mechanisms of antitumor effect of C60 + Dox complex include both its direct action on tumor cells by inducing cell death and increasing of stress sensitivity and an immunomodulating effect. The obtained results provide a scientific basis for further application of C60 + Dox nanocomplexes as treatment agents in cancer chemotherapy.

  16. Growth of large, defect-free pure C60 single crystals

    NASA Technical Reports Server (NTRS)

    Meng, R. L.; Ramirez, D.; Jiang, X.; Chow, P. C.; Diaz, C.; Matsuishi, K.; Moss, S. C.; Hor, P. H.; Chu, C. W.

    1991-01-01

    Millimeter-sized single crystals of C60 were grown by sublimation of C60 powder in a vacuum for 6-24 h. The crystals had excellent facets, were free of C70 or solvent, and showed face-centered cubic symmetry with a very small mosaic spread down to 0.01 deg.

  17. Anion-Dependent Aggregate Formation and Charge Behavior of Colloidal Fullerenes (n-C60)

    EPA Science Inventory

    The fate and transport of colloidal fullerenes (n-C60) in the environment is likely to be guided by electrokinetic and aggregation behavior. In natural water bodies inorganic ions exert significant effects in determining the size and charge of n-C60 nanoparticles. Although the ef...

  18. Conducting films of C60 and C70 by alkali-metal doping

    NASA Astrophysics Data System (ADS)

    Haddon, R. C.; Hebard, A. F.; Rosseinsky, M. J.; Murphy, D. W.; Duclos, S. J.

    1991-03-01

    The preparation is reported of alkali-metal-doped films of C60 and C70 which have electrical conductivities at room temperature comparable to those attained by n-type doped polyacetylene. The highest conductivities observed in the doped films are: 4 S/cm (Cs/C60), 100 (Rb/C60), 500 (K/C60), 20 (Na/C60), 10 (Li/C60), 2 (K/C70). The doping process is reversed on exposure of the films to the atmosphere. At high doping level, the films become more resistive. The conductivity induced in these films is attributed to the formation of energy bands from the pi orbitals of C60 or C70, which become partially filled with carriers on doping. The smaller alkali metal ions should be able to fit into the interstices in the lattice without disrupting the network of contacts between the carbon spheroids. In the case of C60, this would allow the development of an isotropic band structure, and it is proposed that these materials may constitute the first three-dimensional 'organic' conductors.

  19. Electron elastic scattering off A @C60 : The role of atomic polarization under confinement

    NASA Astrophysics Data System (ADS)

    Dolmatov, V. K.; Amusia, M. Ya.; Chernysheva, L. V.

    2015-10-01

    The present paper explores possible features of electron elastic scattering off endohedral fullerenes A @C60 . It focuses on how dynamical polarization of the encapsulated atom A by an incident electron might alter scattering off A @C60 compared to the static-atom-A case, as well as how the C60 confinement modifies the impact of atomic polarization on electron scattering compared to the free-atom case. The aim is to provide researchers with a "relative frame of reference" for understanding which part of the scattering processes could be due to electron scattering off the encapsulated atom and which could be due to scattering off the C60 cage. To meet the goal, the C60 cage is modeled by an attractive spherical potential of a certain inner radius, thickness, and depth which is a model used frequently in a great variety of fullerene studies to date. Then, the Dyson equation for the self-energy part of the Green's function of an incident electron moving in the combined field of an encapsulated atom A and C60 is solved in order to account for the impact of dynamical polarization of the encaged atom upon e +A @C60 scattering. The Ba@C60 endohedral is chosen as the case study. The impact is found to be significant, and its utterly different role compared to that in e +Ba scattering is unraveled.

  20. 40 CFR 721.10267 - [5,6]Fullerene-C60-Ih.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Fullerene-C60-Ih. 721.10267 Section 721.10267 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10267 Fullerene-C60-Ih. (a)...

  1. Effects of humic and fulvic acids on aggregation of aqu/nC60 nanoparticles

    EPA Science Inventory

    Aggregation of fullerene nanoparticles (nC60) is a fundamental process influencing its environmental fate and transport, and toxicity. Using time-resolved dynamic light scattering we systematically investigated aggregation kinetics of nC60 generated from extended mixing in water ...

  2. Nucleation ahead of a C 60 crystal growing from the vapor

    NASA Astrophysics Data System (ADS)

    Schönherr, E.; Matsumoto, K.

    1997-07-01

    Single crystals of the fullerene C 60 are grown by the Pizzarello method in an argon atmosphere. A C 60 nucleus is formed ahead of the growing crystal when a drive rate greater than the limited mass-transfer rate is used. The analysis of the crystal growth rates and temperature distribution reveals a constitutional supersaturation which causes this particular type of nucleation.

  3. Carboxylic Acid Fullerene (C60) Derivatives Attenuated Neuroinflammatory Responses by Modulating Mitochondrial Dynamics

    NASA Astrophysics Data System (ADS)

    Ye, Shefang; Zhou, Tong; Cheng, Keman; Chen, Mingliang; Wang, Yange; Jiang, Yuanqin; Yang, Peiyan

    2015-05-01

    Fullerene (C60) derivatives, a unique class of compounds with potent antioxidant properties, have been reported to exert a wide variety of biological activities including neuroprotective properties. Mitochondrial dynamics are an important constituent of cellular quality control and function, and an imbalance of the dynamics eventually leads to mitochondria disruption and cell dysfunctions. This study aimed to assess the effects of carboxylic acid C60 derivatives (C60-COOH) on mitochondrial dynamics and elucidate its associated mechanisms in lipopolysaccharide (LPS)-stimulated BV-2 microglial cell model. Using a cell-based functional screening system labeled with DsRed2-mito in BV-2 cells, we showed that LPS stimulation led to excessive mitochondrial fission, increased mitochondrial localization of dynamin-related protein 1 (Drp1), both of which were markedly suppressed by C60-COOH pretreatment. LPS-induced mitochondria reactive oxygen species (ROS) generation and collapse of mitochondrial membrane potential (Δ Ψm) were also significantly inhibited by C60-COOH. Moreover, we also found that C60-COOH pretreatment resulted in the attenuation of LPS-mediated activation of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) signaling, as well as the production of pro-inflammatory mediators. Taken together, these findings demonstrated that carboxylic acid C60 derivatives may exert neuroprotective effects through regulating mitochondrial dynamics and functions in microglial cells, thus providing novel insights into the mechanisms of the neuroprotective properties of carboxylic acid C60 derivatives.

  4. Surface Energy of C60 and the Interfacial Interactions in Aqueous Systems

    EPA Science Inventory

    The surface free energy components of C60 powder in the form of compressed pellets were determined by sessile drop contact angle measurements. Based on van Oss-Chaudhury-Good model to Young-Dupre equation, the surface energy of C60 and the contributions of the apolar (Lifshitz-v...

  5. Complex of C60 Fullerene with Doxorubicin as a Promising Agent in Antitumor Therapy.

    PubMed

    Prylutska, Svitlana V; Skivka, Larysa M; Didenko, Gennadiy V; Prylutskyy, Yuriy I; Evstigneev, Maxim P; Potebnya, Grygoriy P; Panchuk, Rostyslav R; Stoika, Rostyslav S; Ritter, Uwe; Scharff, Peter

    2015-12-01

    The main aim of this work was to evaluate the effect of doxorubicin in complex with C60 fullerene (C60 + Dox) on the growth and metastasis of Lewis lung carcinoma in mice and to perform a primary screening of the potential mechanisms of C60 + Dox complex action. We found that volume of tumor from mice treated with the C60 + Dox complex was 1.4 times less than that in control untreated animals. The number of metastatic foci in lungs of animals treated with C60 + Dox complex was two times less than that in control untreated animals. Western blot analysis of tumor lysates revealed a significant decrease in the level of heat-shock protein 70 in animals treated with C60 + Dox complex. Moreover, the treatment of tumor-bearing mice was accompanied by the increase of cytotoxic activity of immune cells. Thus, the potential mechanisms of antitumor effect of C60 + Dox complex include both its direct action on tumor cells by inducing cell death and increasing of stress sensitivity and an immunomodulating effect. The obtained results provide a scientific basis for further application of C60 + Dox nanocomplexes as treatment agents in cancer chemotherapy. PMID:26714861

  6. Photochemistry of Aqueous C60 Clusters: Wavelength Dependency and Product Characterization

    EPA Science Inventory

    To construct accurate risk assessment models for engineered nanomaterials, there is urgent need for information on the reactivity (or conversely, persistence) and transformation pathways of these materials in the natural environment. As an important step toward addressing this is...

  7. Heterostructures based on graphene and MoS2 layers decorated by C60 fullerenes

    NASA Astrophysics Data System (ADS)

    Chernozatonskii, Leonid A.; Kvashnin, Alexander G.; Sorokin, Pavel B.

    2016-09-01

    Here we present a comprehensive investigation of various novel composite structures based on graphene (G) and molybdenum disulphide (MoS2) monolayers decorated by C60 fullerenes, which can be successfully applied in photovoltaics as a solar cell unit. Theoretical studies of the atomic structure, stability and electronic properties of the proposed G/C60, MoS2/C60 and G/MoS2/C60/G nanostructures were carried out. We show that making the G/MoS2/C60/G heterostructure from the 2D films considered here will lead to the appearance of particular properties suitable for application in photovoltaics due to the broad energetic region of high electronic density of states.

  8. Orientational and magnetic ordering of buckyballs in TDAE-C60

    SciTech Connect

    Mihailovic, D.; Arcon, D.; Venturini, P.; Blinc, R.; Omerzu, A.; Cevc, P.

    1995-04-01

    Spin ordering in the low-temperature magnetic phase is directly linked to the orientational ordering of C60 molecules in organically doped fullerene derivatives. Electron spin resonance and alternating current susceptometry measurements on tetrakis (dimethylamino) ethylene-C60 (TDAE-C60) (Curie temperature T(sub c) = 16 kelvin) show a direct coupling between spin and merohedral degrees of freedom. This coupling was experimentally demonstrated by showing that ordering the spins in the magnetic phase imprints a merohedral order on the solid or, conversely, that merohedrally ordering the C60 molecules influences the spin order at low temperature. The merohedral disorder gives rise to a distribution of pi-electron exchange interactions between spins on neighboring C60 molecules, suggesting a microscopic origin for the observed spin-glass behavior of the magnetic state. 18 refs.

  9. Heterostructures based on graphene and MoS2 layers decorated by C60 fullerenes.

    PubMed

    Chernozatonskii, Leonid A; Kvashnin, Alexander G; Sorokin, Pavel B

    2016-09-01

    Here we present a comprehensive investigation of various novel composite structures based on graphene (G) and molybdenum disulphide (MoS2) monolayers decorated by C60 fullerenes, which can be successfully applied in photovoltaics as a solar cell unit. Theoretical studies of the atomic structure, stability and electronic properties of the proposed G/C60, MoS2/C60 and G/MoS2/C60/G nanostructures were carried out. We show that making the G/MoS2/C60/G heterostructure from the 2D films considered here will lead to the appearance of particular properties suitable for application in photovoltaics due to the broad energetic region of high electronic density of states. PMID:27478999

  10. Energetics and Electronic Structures of C60 Included Within [n]Cyclacene Molecules

    NASA Astrophysics Data System (ADS)

    Kigure, Shota; Okada, Susumu

    2013-09-01

    We report the geometric and electronic structures of C60 included within cyclic hydrocarbon molecules, i.e., [n]cyclacene molecules. We found that the C60 included within the [n]cyclacene molecules ([n]cyclacene\\supsetC60) are energetically stable and that the inclusion reactions are exothermic for the [n]cyclacene molecules where n is larger than 16. Because of quantum confinement of the electronic states of the guest C60 molecule by the host [n]cyclacene, the electronic structure of [n]cyclacene\\supsetC60 is complex. The energy gap between the highest occupied states and the lowest unoccupied states is opened between the electronic states of the guest and host molecules.

  11. Raman study on a bulk-heterojunction film of pentacene and C60

    NASA Astrophysics Data System (ADS)

    Iwasawa, Yasuhiro; Furukawa, Yukio

    2015-09-01

    We measured the 785-nm excited Raman spectrum of a pentacene:C60 blend film. The 1462-, 492-, and 268-cm-1 bands of C60 showed broadening in bandwidth and downward shifts in peak wavenumbers, whereas such broadening and downward shifts were not observed for pentacene. These results indicate that there are pentacene crystallites among the amorphous C60. The intensity ratio of the 1598-cm-1 (B3g) and the 1534-cm-1 (Ag) bands indicates that pentacene molecules have standing orientations. The appearance of a 514-cm-1 band (F1u) and the splitting of the Hg bands of C60 indicate symmetry lowering induced by the interaction between pentacene and C60 molecules.

  12. From Planar to Cage in 15 Easy Steps: Resolving the C60H21F9(-) → C60(-) Transformation by Ion Mobility Mass Spectrometry.

    PubMed

    Greisch, Jean-François; Amsharov, Konstantin Yu; Weippert, Jürgen; Weis, Patrick; Böttcher, Artur; Kappes, Manfred M

    2016-09-01

    A combination of mass spectrometry, collision-induced dissociation, ion mobility mass spectrometry (IM-MS), and density functional theory (DFT) has been used to study the evolution of anionic species generated by laser-desorption of the near-planar, fluorinated polycyclic aromatic hydrocarbon (PAH), C60H21F9 (s). The dominant decay process for isolated, thermally activated C60H21F9(-) species comprises a sequence of multiple regioselective cyclodehydrofluorination and cyclodehydrogenation reactions (eliminating HF and H2, respectively, while forming additional pentagons and/or hexagons). The DFT calculations allow us to set narrow bounds on the structures of the resulting fragment ions by fitting structural models to experimentally determined collision cross sections. These show that the transformation of the precursor anion proceeds via a series of intermediate structures characterized by increasing curvature, ultimately leading to the closed-shell fullerene cage C60(-) as preprogrammed by the precursor structure. PMID:27501376

  13. The Curators of the University of Missouri Modeling the Infrared Emission of C_60 in Space

    NASA Astrophysics Data System (ADS)

    Li, Aigen

    Fullerenes are cage-like molecules of pure carbon, such as C_60, C_70, C_76, and C_84. C_60, also known as buckminsterfullerene, is the most stable fullerene and has a soccer- ball like structure. The presence of fullerenes in space has been suggested and observationally explored since their first synthesis in the laboratory in 1985 by Harry Kroto and his colleagues which earned them the 1996 Nobel prize in chemistry. C_60 (as well as C_70) has recently been detected in reflection nebulae, post-AGB stars, protoplanetary nebulae, planetary nebulae, Herbig Ae/Be stars, and young stellar objects through their characteristic infrared emission bands. The formation of C_60 in interstellar and circumstellar environments is not firmly established. Experimental studies have shown that C_60 can be made by gas-phase condensation (e.g. through vaporization of graphite) in a hydrogen-poor environment. In view of the simultaneous detection of C_60 and PAHs in hydrogen-rich interstellar and circumstellar regions, it has also been suggested that C_60 could be generated by the decomposition of hydrogenated amorphous carbon, or the destruction of PAHs, both induced by shocks and/or UV photoprocessing. The phase (gas or solid) and excitation mechanism of C_60 in interstellar and circumstellar conditions are also hotly debated in the literature. One model suggests that C_60 is attached to dust and emits in solid-phase at the equilibrium temperature of the dust. Another model suggests that C_60 is stochastically excited by UV photons and emits in the gas-phase. We prefer the latter model as in interstellar and circumstellar conditions the energy content of a C_60 molecule is often smaller than the energy of a single starlight photon and C_60 is expected to undergo stochastical heating. We propose a two-year project to model the vibrational excitation of C_60 and calculate its infrared emission spectra in a wide variety of regions (e.g. reflection nebulae excited by stars of a range of

  14. Probing Exciton Diffusion and Dissociation in Single-Walled Carbon Nanotube-C60 Heterojunctions.

    PubMed

    Dowgiallo, Anne-Marie; Mistry, Kevin S; Johnson, Justin C; Reid, Obadiah G; Blackburn, Jeffrey L

    2016-05-19

    The efficiency of thin-film organic photovoltaic (OPV) devices relies heavily upon the transport of excitons to type-II heterojunction interfaces, where there is sufficient driving force for exciton dissociation and ultimately the formation of charge carriers. Semiconducting single-walled carbon nanotubes (SWCNTs) are strong near-infrared absorbers that form type-II heterojunctions with fullerenes such as C60. Although the efficiencies of SWCNT-fullerene OPV devices have climbed over the past few years, questions remain regarding the fundamental factors that currently limit their performance. In this study, we determine the exciton diffusion length in the C60 layer of SWCNT-C60 bilayer active layers using femtosecond transient absorption measurements. We demonstrate that hole transfer from photoexcited C60 molecules to SWCNTs can be tracked by the growth of narrow spectroscopic signatures of holes in the SWCNT "reporter layer". In bilayers with thick C60 layers, the SWCNT charge-related signatures display a slow rise over hundreds of picoseconds, reflecting exciton diffusion through the C60 layer to the interface. A model based on exciton diffusion with a Beer-Lambert excitation profile, as well as Monte Carlo simulations, gives the best fit to the data as a function of C60 layer thickness using an exciton diffusion length of approximately 5 nm. PMID:27127916

  15. Spectroscopical study on C 60 and C 70 fullerene solutions in superacids

    NASA Astrophysics Data System (ADS)

    Cataldo, Franco

    1995-03-01

    The electronic spectra of solutions of C 60 fullerene in superacids of comparable strength have been studied. A similar study has been conducted over solutions of decacyclene, a polycyclic aromatic, used as model compound. In oleum, C 60 initially forms a charge transfer complex probably with free SO 3 present in the medium as indicated by a new band which arises at 827 nm. Then this band decreases and two new maxima at 930 and 1005 nm indicate the formation of C 60 radical cation as a result of oxidation of fullerene. In CF 3SO 3H, C 60 do not show any charge-transfer interaction with solvent and only when it is treated with an oxidizing agent like K 2S 2O 8, a new band develops at 965 nm with a shoulder at 1046 nm, indicating the formation of a cation radical. The spectra of C 60 radical cation are in agreement with previous observations in frozen matrix and with theoretical predictions; moreover these spectra are also similar to that of C 60 radical anion. The behavior in oleum of graphite and photochlorinated C 60 has also been studied. The spectrum of C 70 radical cation has been observed in oleum and is characterized by a new band in the 600-650 nm spectral region.

  16. Theoretical study of the charge transport through C60-based single-molecule junctions

    NASA Astrophysics Data System (ADS)

    Bilan, S.; Zotti, L. A.; Pauly, F.; Cuevas, J. C.

    2012-05-01

    We present a theoretical study of the conductance and thermopower of single-molecule junctions based on C60 and C60-terminated molecules. We first analyze the transport properties of gold-C60-gold junctions and show that these junctions can be highly conductive (with conductances above 0.1G0, where G0=2e2/h is the quantum of conductance). Moreover, we find that the thermopower in these junctions is negative due to the fact that the lowest unoccupied molecular orbital dominates the charge transport, and its magnitude can reach several tens of microvolts per kelvin, depending on the contact geometry. On the other hand, we study the suitability of C60 as an anchoring group in single-molecule junctions. For this purpose, we analyze the transport through several dumbbell derivatives using C60 as anchors, and we compare the results with those obtained with thiol and amine groups. Our results show that the conductance of C60-terminated molecules is rather sensitive to the binding geometry. Moreover, the conductance of the molecules is typically reduced by the presence of the C60 anchors, which in turn makes the junctions more sensitive to the functionalization of the molecular core with appropriate side groups.

  17. Polyamide 12/ fullerene C60 composites: Investigation on their mechanical and dielectric properties

    NASA Astrophysics Data System (ADS)

    Zuev, Vjacheslav V.

    2014-05-01

    The effect of fullerene C60 on mechanical properties of polymer nanocomposites based on PA12 was investigated. The nanocomposites were prepared by in situ polymerization. The Young's modulus and tensile strength of the polymer nanocomposites are improved by about 20% with loading of 0.02-0.08 wt.% the fullerene C60. Dielectric spectroscopy was used to investigate the influence of nanoparticles on the relaxation processes in polymer matrix. The segmental relaxation processes become faster with the fullerene C60 addition, an effect associated with a decrease of the glass transition temperature. In contrast, the secondary or γ relaxation process of PA12/ fullerene C60 nanocomposites was observed to slow down with addition of fullerene C60. These observations indicate that fullerene C60 as filler has an effect opposite to antiplasticizing that slow down the secondary relaxation (stiffening the material) in the glass state, while at the same time reducing the alpha relaxation time associated with cooperative segmental motions. It behaviour can be connected with inclusion complex formation between PA12 and fullerene C60.

  18. Polymeric fullerene chains in RbC60 and KC60

    NASA Astrophysics Data System (ADS)

    Stephens, Peter W.; Bortel, G.; Faigel, G.; Tegze, M.; Jánossy, A.; Pekker, S.; Oszlanyi, G.; Forró, L.

    1994-08-01

    NEARLY all of the molecular crystals containing C60, formed at ambient pressure1,2 have inter-fullerene separations of the order of 10 Å - the expected distance based on the molecular van der Waals radii. The sole exceptions are the room-temperature phases of AC60 (where A denotes K, Rb or Cs), which are formed by reversible solid-state transformation from high-temperature (>150 °C) phases3. These phases have lattice parameters about 9% shorter in one direction, and in addition RbC60 has magnetic properties suggestive of a one-dimensional metal4. We suggested in ref. 4 that this short distance may be due to covalent bonding between neighbouring C60 molecules. Here we provide direct evidence for such bonding from powder X-ray diffraction studies of RbC60 and KC60 . The linkage is through a [2+2] cycloaddition, which has been hypothesized to take place during photopolymerization of solid C60 (ref. 5), and which has also been proposed6 for RbC60. Such inter-fullerene linkages are calculated7,8 to be the preferred mode of dimerization of C60. The AC60 phases thus provide an example of a thermal phase transition driven by the reversible formation and breaking of covalent bonds.

  19. STM study of C60F18 high dipole moment molecules on Au(111)

    NASA Astrophysics Data System (ADS)

    Bairagi, K.; Bellec, A.; Chumakov, R. G.; Menshikov, K. A.; Lagoute, J.; Chacon, C.; Girard, Y.; Rousset, S.; Repain, V.; Lebedev, A. M.; Sukhanov, L. P.; Svechnikov, N. Yu.; Stankevich, V. G.

    2015-11-01

    Scanning tunneling microscopy and spectroscopy studies of C60F18 molecules deposited on Au(111) are reported and compared to C60 molecules both at liquid helium temperature and room temperature (RT). Whereas adsorption and electronic properties of C60F18 single molecules were studied at low temperature (LT), self-assemblies were investigated at RT. In both cases, the fluorine atoms of the C60F18 molecules are pointed towards the surface. Individual C60F18 molecules on Au(111) have a HOMO-LUMO gap of 2.9 eV. The self-assembled islands exhibit a close-packed hexagonal lattice with amorphous borders. The comparison with C60 molecules clearly demonstrates the influence of the C60F18 electric dipole moment (EDM) on the electronic properties of single molecules and on the thermodynamics of self-assembled islands. Besides, the apparent height value of a separate molecule increases in a self-assembly environment as a result of a depolarization phenomenon.

  20. Effects of screening of the final-state A^+ ion static potential within the C60 on A@C60 photoionization.

    NASA Astrophysics Data System (ADS)

    Dolmatov, Valeriy; Guler, Emre; Manson, Steven

    2010-03-01

    We perform a novel, trial study of photoionization of an atom A in the A@C60 endohedral fullerene within the framework of the model [1] which regards C60 as a conducting sphere, approximated by an attractive square-well potential VC60(r) of a given inner radius, depth, and thickness. In the present study, we explore the possible shielding, both partial and complete, of the Coulomb potential of the final-state A^+ ion by the C60 in the region between the inner and outer radii of VC60(r). This effect has not been studied previously and its significance remained unknown. Using the example of Ne@C60, we find that, fortunately, the effect of the shielding on the photoionization of endohedral atoms is relatively small; no more than 20% near threshold for a complete screening, and much less at higher energies. Thus, the results and predictions of earlier studies are not significantly impacted by this shielding and future studies may ignore the shielding effect, to a good approximation. [4pt] [1] V. K. Dolmatov. In: Theory of Confined Quantum Systems: Part Two, edited by J. R. Sabin and E. Brändas, Advances in Quantum Chemistry (Academic Press, New York, 2009), Vol. 58, pp. 13-68.

  1. Orientation-Dependent C60 Electronic Structures Revealed byPhotoemission Spectroscopy

    SciTech Connect

    Brouet, V.; Yang, W.L.; Zhou, X.J.; Choi, H.J.; Louie, S.G.; Cohen, M.L.; Goldoni, A.; Parmigiani, F.; Hussain, Z.; Shen, Z.X.

    2004-11-05

    We observe, with angle-resolved photoemission, a dramatic change in the electronic structure of two C60 monolayers, deposited,respectively, on Ag (111) and (100) substrates, and similarly doped with potassium to half filling of the C60 lowest unoccupied molecular orbital.The Fermi surface symmetry, the bandwidth, and the curvature of the dispersion at Gamma point are different. Orientations of the C60molecules on the two substrates are known to be the main structural difference between the two monolayers, and we present new band-structure calculations for some of these orientations. We conclude that orientations play a key role in the electronic structure of fullerides.

  2. Enhanced brain penetration of hexamethonium in complexes with derivatives of fullerene C60.

    PubMed

    Piotrovskiy, L B; Litasova, E V; Dumpis, M A; Nikolaev, D N; Yakovleva, E E; Dravolina, O A; Bespalov, A Yu

    2016-05-01

    The present report describes development of hexamethonium complexes based on fullerene C60. Hexamethonium has a limited penetration into CNS and therefore can antagonize central effects of nicotine only when given at high doses. In the present studies conducted in laboratory rodents, intraperitoneal administration of hexamethonium-fullerene complexes blocked effects of nicotine (convulsions and locomotor stimulation). When compared to equimolar doses of hexamethonium, complexes of hexamethonium with derivatives of fullerene C60 were 40 times more potent indicating an enhanced ability to interact with central nicotine receptors. Thus, fullerene C60 derivatives should be explored further as potential carrier systems for polar drug delivery into CNS. PMID:27417712

  3. Electronic pair binding and Hund's rule violations in doped C60

    NASA Astrophysics Data System (ADS)

    Jiang, Hong-Chen; Kivelson, Steven

    2016-04-01

    We calculate the electronic properties of the t -J model on a C60 molecule using the density-matrix renormalization group and show that Hund's first rule is violated and that for an average of three added electrons per molecule, an effective attraction (pair binding) arises for intermediate values of t /J . Specifically, it is energetically favorable to put four electrons on one C60 and two on a second rather than putting three on each. Our results show that a dominantly electronic mechanism of superconductivity is possible in doped C60.

  4. James C. McGroddy Prize Talk: What Was New About C60

    NASA Astrophysics Data System (ADS)

    Haddon, Robert

    2008-03-01

    C60 was named molecule of the year by Science in 1991, and in this talk I will discuss what I consider to be the most novel features of the molecule. In some ways C60 is truly unique and the discovery of the molecule in 1985 and its subsequent synthesis in 1990 blazed a trail of new chemical and physical properties that is unlikely to be surpassed by any other molecule. I will discuss the electronic structure of C60, its magnetism, and the conductivity and superconductivity shown by the alkali metal-doped phases.

  5. Relationship between indium tin oxide surface treatment and hole injection in C60 modified devices

    NASA Astrophysics Data System (ADS)

    Kim, Sung Hyun; Jang, Jyongsik; Lee, Jun Yeob

    2006-12-01

    The effect of indium tin oxide (ITO) surface treatment on hole injection in organic light-emitting diode with C60 as a buffer layer on ITO was studied. Double surface dipole layer was induced on oxygen plasma treated ITO surface, while no dipole formation was observed on ITO without surface treatment. Interfacial energy barrier between ITO and hole transport layer was reduced by 0.4eV by C60 modification on oxygen plasma treated ITO surface, while there was no change of interfacial energy barrier by C60 on ITO without surface treatment.

  6. Progress in the Development of a C60 Plasma Gun for Disruption Mitigation

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Thompson, J. R.; Galkin, S. A.; Kim, J. S.; Case, A.; Messer, S. J.; Brockington, S.; Witherspoon, F. D.

    2010-11-01

    We present the status of a C60-fullerene plasma gun prototype proposed to be used for disruption mitigation with high-density, hyper-velocity plasma jets on ITER. The key element is the TiH2/C60 pulsed power, solid state cartridge source. We performed modeling and simulations of the processes critical to the cartridge design. Transient heating of TiH2 packed grains, explosive sublimation of C60 micron size powder, high pressure buildup, ejection of the molecular gas mixture through nozzles, adiabatic expansion of the plasma jet upon ejection from a plasma gun muzzle, and plasma jet penetration through transverse magnetic field were investigated. We show how we incorporated the results into the design of the TiH2/C60 cartridge source. Measurements characterizing the molecular gas jet produced by the cartridge source will be presented.

  7. Optimization of the Thermoelectric Figure of Merit in Crystalline C60 with Intercalation Chemistry.

    PubMed

    Kim, Jeong Yun; Grossman, Jeffrey C

    2016-07-13

    Crystalline C60 is an appealing candidate material for thermoelectric (TE) applications due to its extremely low thermal conductivity and potentially high electrical conductivity with metal atom intercalation. We investigate the TE properties of crystalline C60 intercalated with alkali and alkaline earth metals using both classical and quantum mechanical calculations. For the electronic structure, our results show that variation of intercalated metal atoms has a large impact on energy dispersions, which leads to broad tunability of the power factor. For the thermal transport, we show that dopants introduce strong phonon scattering into crystalline C60, leading to considerably lower thermal conductivity. Taking both into account, our calculations suggest that appropriate choice of metal atom intercalation in crystalline C60 could yield figures of merit near 1 at room temperature. PMID:27322341

  8. Electron propagator calculations on the ground and excited states of C60(-).

    PubMed

    Zakrzewski, V G; Dolgounitcheva, O; Ortiz, J V

    2014-09-01

    Electron propagator calculations in two approximations—the third-order algebraic, diagrammatic construction and the outer valence Green’s function (OVGF)—have been performed on the vertical electron affinities of C60 and the vertical electron detachment energies of several states of C60(–) with a variety of basis sets. These calculations predict bound (2)T1u and (2)T1g anions, but fail to produce (2)T2u or (2)Hg anionic states that are more stable than ground-state C60. The electron affinity for the (2)Ag state is close to zero, but no definitive result on its sign has been obtained. This state may be a resonance or marginally bound anion. The OVGF prediction for the vertical electron detachment energy of (2)T1u C60(–), 2.63 eV, is in excellent agreement with recent anion photoelectron spectra. PMID:24813804

  9. Preparation and surface enhanced Raman scattering behavior of Ag-coated C60 nanoclusters

    NASA Astrophysics Data System (ADS)

    Kang, Shi-Zhao; Yin, Die-er; Li, Xiangqing; Mu, Jin

    2013-12-01

    Ag-coated C60 nanoclusters were prepared and characterized with X-ray diffraction, transmission electron microscopy and nitrogen adsorption-desorption isotherm measurement. The Ag-coated C60 nanoclusters were assembled on the glass substrate to form a thin film using the layer-by-layer technique. Meanwhile, the surface enhanced Raman scattering (SERS) of musk xylene adsorbed on the film of Ag-coated C60 nanoclusters was explored. The results indicated that the film of Ag-coated C60 nanoclusters was a unique SERS-active substrate with a detection limit of 10-9 mol L-1 for musk xylene. Furthermore, the surface enhanced mechanisms were discussed preliminarily.

  10. Energetics and Electronic Structure of Na-Doped Rhombohedral C60 Polymers

    NASA Astrophysics Data System (ADS)

    Tasuku Chiba,; Susumu Okada,

    2010-08-01

    Based on a first-principles total-energy calculation, we studied the energetics and electronic structure of a Na-doped rhombohedral C60 polymer. The intercalation of Na atoms into the interstitial sites of the C60 polymer studied here is an exothermic process with an energy gain of about 1 eV per Na atom. A detailed analysis of the polymer energetics revealed that the tetrahedral interstitial site is favorable as an intercalation site because of the strong Coulombic interaction between Na and C60. The electronic structure of the NaxC60 polymers are metallic in nature with a partially filled electronic energy band at the Fermi level.

  11. Structural transitions of SWNT filled with C60 under high pressure

    NASA Astrophysics Data System (ADS)

    Yong-gang, Zou; Li, Xu; Kun, Tian; He, Zhang; Xiao-hui, Ma; Ming-guang, Yao

    2016-05-01

    Raman spectra of C60 filled single-walled carbon nanotubes (C60@SWNTs) with diameters of 1.3–1.5 nm have been studied under high pressure. A plateau in the pressure dependence of the G-band frequency at around 10 GPa was observed in both experiments with 514 nm and 830 nm excitation lasers, which is similar to the high pressure behaviors of pristine SWNTs. This structural transition has been assigned to the transformation into a peanut-like structure of the nanotubes. At pressure below 2 GPa, no obvious Raman signature related to the structural transition of nanotubes was observed, unlike what has been reported for C70 filled nanotubes. We discussed this point in terms of the arrangement differences of C60 and C70 molecules inside the nanotubes. At higher pressure up to 15 GPa, a graphite-like pressure evolution was observed in our C60@SWNTs.

  12. Preparation of C60 by Detonation a Mixture of Trinitrotoluene and Graphite

    NASA Astrophysics Data System (ADS)

    Wei, Xianfeng; Han, Yong; Liu, Liu; Long, Xinping

    2013-01-01

    To explore the practicability of C60 synthesis under extreme conditions (high pressure and high temperature), trinitrotoluene (TNT), trinitramine (RDX) and graphite mixtures of different proportions were detonated in a vacuum container, and the detonation products were collected for detecting. The results of mass spectroscopy, high performance liquid chromatography showed significant signals of C60, which proved that C60 could be synthesized by detonating the mixture of TNT and graphite (in 6:4 and 7:3 mass ratio, respectively), the detonation pressure and temperature were calculated around 13 GPa and 2000 K, respectively. Both experiment results and theoretical analysis showed the importance of detonation pressure and cooling temperature in detonation synthesis of C60.

  13. Modulation of nanocavity plasmonic emission by local molecular states of C60 on Au(111).

    PubMed

    Geng, Feng; Zhang, Yang; Yu, Yunjie; Kuang, Yanmin; Liao, Yuan; Dong, Zhenchao; Hou, Jianguo

    2012-11-19

    We investigate the modulation of C60 monolayers on the nanocavity plasmonic (NCP) emission on Au(111) by tunneling electron excitation from a scanning tunneling microscope (STM) tip. STM induced luminescence spectra show not only suppressed emission, but also significant redshift of NCP emission bands on the C60 molecules relative to the bare metal surface. The redshift, together with the bias- and coverage-dependent emission feature, indicates that the C60 molecules act beyond a pure dielectric spacer, their electronic states are heavily involved in the inelastic tunneling process for plasmonic emission. A modified quantum cutoff relation is proposed to explain qualitatively the observed emission feature at both bias polarities. We also demonstrate molecularly resolved optical contrast on the C60 monolayer and discuss the contrast mechanism briefly. PMID:23187525

  14. A 2:1 receptor/C60 complex as a nanosized universal joint.

    PubMed

    Yanney, Michael; Fronczek, Frank R; Sygula, Andrzej

    2015-09-14

    Buckycatcher II, a C51 H24 hydrocarbon with two corannulene pincers on a dibenzonorbornadiene tether, exhibits an affinity toward C60 in organic solvents that is dramatically higher than the original buckycatcher C60 H28 and other corannulene-based molecular receptors for fullerenes. In addition to the formation of an usual 1:1 C60 @catcher inclusion complex, a trimeric C60 @(catcher)2 assembly is detected in solutions and in the solid state. X-ray structure determination reveals a remarkable "universal joint" solvent-free crystal arrangement of the trimer, with a single fullerene cage wrapped by four corannulene subunits of two cooperating catcher receptors. PMID:26352025

  15. Photoelectric properties of unsymmetrical metal-free phthalocyanine and C60 complex thin films

    NASA Astrophysics Data System (ADS)

    Yang, Zhigang; Shen, Yue; Zhang, Jiancheng

    2004-12-01

    In this paper, novel one amino-group substituted unsymmetrical metal-free phthalocyanine (AUMPc) was synthesized, then the complex of AUMPc with C60 (The Complex) was obtained in the mixed solvents. Ultraviolet-visible (Uv-vis) spectrophotometer, fluorescence spectrophotometer and home-made photoconductivity meter were used to study the photoelectric properties of AUMPc and the complex. It was found that the absorbance of The Complex was larger than that of the total of AUMPc and C60 in the B belt (333nm), the absorbance of The Complex in the Q belt (693nm) where C60 had no absorbance was also increased. C60 took the role as annihilation in AUMPc, the photoconductivity of the Complex thin film was clearly increased when the film was exposed in the light.

  16. Development of a C 60+ ion gun for static SIMS and chemical imaging

    NASA Astrophysics Data System (ADS)

    Wong, S. C. C.; Hill, R.; Blenkinsopp, P.; Lockyer, N. P.; Weibel, D. E.; Vickerman, J. C.

    2003-01-01

    This paper reports initial data from the application of the first dedicated buckminsterfullerene ion beam system developed for routine use on existing ToF-SIMS instruments for static SIMS and chemical imaging. The ion gun provides a selectable beam of C 60+ and C 602+ primary ions, producing a nA beam of C 60+ focusable to 1 μm spot size. The results of comparative studies of bulk polymers and thin films using C 60+ and Ga + ions are presented. Compared to Ga +, C 60+ provides a very substantial increase in real ion yields, especially at high mass, with no concomitant increase in the relative yield of low mass fragments.

  17. Transport characteristics of a single C60-molecule junction revealed by multiple Andreev reflections

    NASA Astrophysics Data System (ADS)

    Hiraoka, Ryoichi; Arafune, Ryuichi; Tsukahara, Noriyuki; Kawai, Maki; Takagi, Noriaki

    2014-12-01

    We have determined the number of transport channels and the value of the transmission coefficients of a single molecular junction by measuring the multiple Andreev reflections (MARs) with a scanning tunneling microscope (STM). By precisely positioning a Nb STM tip to a single C60 molecule on Pb(111), a single molecular junction was fabricated in which the C60 molecule connects with the two superconducting electrodes. From the subharmonic gap structures arising from MARs in the current-voltage characteristics together with the tunneling spectrum of the C60 molecule, we found that unoccupied molecular orbitals of C60 extending to the Fermi level provide three electronic transport channels in the molecular junction. We also found that the transmission coefficients depend on the contact geometry of the molecule. These results demonstrate that the combination of the STM imaging with the MARs measurement provides an effective path for investigating the electronic transport properties through a single molecule sandwiched by two superconducting electrodes.

  18. Tuning the molecular order of C60 functionalized phosphonic acid monolayers.

    PubMed

    Rumpel, Armin; Novak, Michael; Walter, Johannes; Braunschweig, Björn; Halik, Marcus; Peukert, Wolfgang

    2011-12-20

    Mixed self-assembled monolayers (SAM) of alkyl phosphonic acids and C(60) functionalized octadecyl phosphonic acids (C(60)C(18)-PA) are deposited on alumina substrates from solution and are shown to form well-ordered structures with an insulating layer of alkyl chains and a semiconducting layer that comprises mainly C(60). Such an ordered structure is a necessity for the application of SAMs in organic transistors but is difficult to obtain since C(60)C(18)-PA without additional support do self-assemble in dense packaging but not in a well-ordered fashion. To avoid disordering of the SAM and to gain a better control of the interfacial properties we have investigated the stabilizing effects of fluorinated dodecyl phosphonic acids (FC(12)-PA) on the C(60)C(18)-PA monolayer. Vibrational sum-frequency (SFG) spectroscopy, ellipsometry, X-ray photoelectron spectroscopy, and electrical measurements were applied to study the mixed monolayers. Here, we make use of the differently labeled PA to determine surface coverages and molecular properties of the two species independently. Adsorption of FC(12)-PA gives rise to vibrational bands at 1344 cm(-1) and 1376 cm(-1) in SFG spectra, while a pronounced vibrational band centered at 1465 cm(-1) is attributable to C(60) vibrations. The coexistence of the bands is indicative for the presence of a mixed monolayer that is composed of both molecular species. Furthermore, a pronounced maximum in SFG intensity of the C(60) band is observed for SAMs, which are deposited from solutions with ~75% C(60)C(18)-PA and ~25% FC(12)-PA. The intensity maximum originates from successful stabilization of C(60) modified C(60)C(18)-PA by FC(12)-PA and a significantly improved molecular order. Conclusions from SFG spectra are corroborated by electric measurements that show best performance at these concentrations. Our results provide new information on the morphology and composition of C(60) modified SAMs and establish a route to fabricate well

  19. Enhanced association for C70 over C60 with a metal complex with corannulene derivate ligands.

    PubMed

    Álvarez, Celedonio M; García-Escudero, Luis A; García-Rodríguez, Raúl; Martín-Álvarez, Jose M; Miguel, Daniel; Rayón, Víctor M

    2014-11-14

    The geometry imposed by the coordination sphere around the metal, together with the choice of the "arms" can be advantageously used to build corannulene-based molecular tweezers, which show great affinities for C60 and C70, as revealed by NMR titration experiments, mass spectroscopy, DFT calculations and the single crystal X-ray structural analysis of the compound C60 ⊂1. PMID:25181755

  20. Experimental evidence of a dynamic Jahn-Teller effect in C-60(+)

    SciTech Connect

    Canton, S.E.; Yencha, A.J.; Kukk, E.; Bozek, J.D.; Lopes, M.C.A.; Snell, G.; Berrah, N.

    2002-05-20

    Detailed analysis of the HOMO bandshape in the photoelectron spectrum of gaseous C60 reveals a dynamic Jahn-Teller effect in the ground state of C60+. The direct observation of three tunneling states asserts a D3d geometry for the isolated cation, originating from a strong vibronic coupling. These results show that the ionic motion of the ions plays an important role in the electron-phonon interaction.

  1. Anion-Dependent Aggregate Formation and Charge Behavior of Colloidal Fullerenes (n-C60)

    NASA Astrophysics Data System (ADS)

    Mukherjee, B.; Weaver, J. W.

    2009-12-01

    The fate and transport of colloidal fullerenes (n-C60) in the environment are likely to be guided by their electrokinetic and aggregation behavior. In natural water bodies inorganic ions exert significant effects in determining the size and charge of dispersed n-C60. Although the effects of cations on the behavior of n-C60 have been studied extensively; studies on the effect of anions are relatively few and thus were the focus of our investigation. The effects of anions (e.g., Cl- , SO42-) on average aggregate size (DH) and zeta potential (ZP) of n-C60 were found to be absent in presence of monovalent cations (e.g., Na+) over the tested range of pH (3-to-12) and ionic strength (0-to-20 mM). Similar observations were noted in the presence of multivalent cations (e.g., Mg2+) near acidic and neutral pH conditions. However, under alkaline conditions (pH~10) a strong anion-dependent reversal of surface charge was noted. The ZP of n-C60 changed from -65 mV, when dispersed in DI water, to +4 mV and +40 mV in the presence of SO42- and Cl-, respectively in a 10mM salt concentration (i.e., MgCl2 and MgSO4). The corresponding DH of the dispersed n-C60 changed simultaneously from 115 nm, in DI water, to 1450 nm and 225 nm for the MgSO4 and MgCl2 electrolytes. These findings provide a better understanding of interfacial interaction characteristics of n-C60 NPs, and may lead to remediation strategies for n-C60 NPs in the environment.

  2. Film growth and surface reactions of C60 on Si(100)H(2×1)

    NASA Astrophysics Data System (ADS)

    Schmidt, J.; Hunt, M. R. C.; Miao, P.; Palmer, R. E.

    1997-10-01

    High-resolution electron-energy-loss spectroscopy (HREELS) has been used to characterize C60 films up to 4 monolayers thick grown at room temperature on hydrogen-terminated Si(100). Our results show that compared with C60 films on clean Si(100) surfaces a considerably higher degree of order in the as-deposited films is achieved. At low coverages the observed C60 vibrational modes and the Si-H vibrations of the substrate are essentially unshifted, indicating a van der Waals-type interaction between C60 and Si(100)H(2×1). After annealing at 450 K the film order is substantially increased. Annealing at 600 K results in desorption of the C60 multilayers and a hydrogen-transfer reaction from the surface to the adsorbed monolayer molecules. When annealing the sample at 800 K, the remaining surface terminating hydrogen desorbs and evidence for a change in the C60 bonding configuration is found. Finally, flashing the sample at 1300 K leads to the formation of silicon carbide.

  3. Transmission properties of C60 ions through micro- and nano-capillaries

    NASA Astrophysics Data System (ADS)

    Tsuchida, Hidetsugu; Majima, Takuya; Tomita, Shigeo; Sasa, Kimikazu; Narumi, Kazumasa; Saitoh, Yuichi; Chiba, Atsuya; Yamada, Keisuke; Hirata, Koichi; Shibata, Hiromi; Itoh, Akio

    2013-11-01

    We apply the capillary beam-focusing method for the C60 fullerene projectiles in the velocity range between 0.14 and 0.2 a.u. We study the C60 transmission properties through two different types of capillaries: (1) borosilicate glass microcapillary with an outlet diameter of 5.5 μm, and (2) Al2O3 multi-capillary foil with a pore size of about 70 nm and a high aspect ratio of about 750. We measured the transmitted particle composition by using the electrostatic deflection method combined with the microchannel plate imaging technique. For the experiments with the single microcapillary, the main transmission component is found to be primary C60 beams that are focused in the area equal to the capillary outlet diameter. Minor components are charge-exchanged C60 ions and charged or neutral fragments (fullerene-like C60-2m and small Cn particles), and their fractions decrease with decreasing the projectile velocity. It is concluded that the C60 transmission fraction is considerably high for both types of the capillaries in the present velocity range.

  4. Electrical Transport Properties of C60 Single Crystals Doped with Alkali Metals

    NASA Astrophysics Data System (ADS)

    Ogata, Hironori; Maruyama, Yusei; Inabe, Tamotsu; Achiba, Yohji; Suzuki, Sinzo; Kikuchi, Koichi; Ikemoto, Isao

    Electronic structures of various kinds of alkali metal (Na, K, Rb or Cs)-doped C60 solids are studied by electrical resistivity and thermoelectric power measurements by using C60 single crystals prepared from a CS2 solution as a starting material. For K-or Rb-doped C60, metallic conducting behaviors in the normal conducting state and relatively sharp superconducting transitions are observed by the electrical resistivity measurements. Nearly linear-temperature dependences with the negative sign are observed in the thermoelectric power measurements at the normal conducting states for K-or Rb-doped C60. From electron diffusion term of the thermoelectric power, the values of Fermi energy and the density of states at the Fermi energy are estimated by assuming the three-dimensional free electron model, which are in substantial agreement with the results of other experiments and calculations. "Metal-semiconductor transition" is observed in both the electrical resistivity and the thermoelectric power measurements for Na-doped C60. Existence of metallic phase is confirmed by the thermoelectric power measurement in Cs-doped C60.

  5. The applications of buckminsterfullerene C60 and derivatives in orthopaedic research

    PubMed Central

    Liu, Qihai; Cui, Quanjun; Li, Xudong Joshua; Jin, Li

    2014-01-01

    Buckminsterfullerene C60 and derivatives have been extensively explored in biomedical research due to their unique structure and unparalleled physicochemical properties. C60 is characterized as a “free radical sponge” with an anti-oxidant efficacy several hundred-fold higher than conventional anti-oxidants. Also, the C60 core has a strong electron-attracting ability and numerous functional compounds with widely different properties can be added to this fullerene cage. This review focused on the applications of C60 and derivatives in orthopaedic research, such as the treatment of cartilage degeneration, bone destruction, intervertebral disc degeneration (IVDD), vertebral bone marrow disorder, radiculopathy, etc., as well as their toxicity in vitro and in vivo. We suggest that C60 and derivatives, especially the C60 cores coupled with functional groups presenting new biological and pharmacological activities, are advantageous in orthopaedic research and will be promising in clinical performance for musculoskeletal disorders treatment; however, the pharmacokinetics and toxicology of these agents as local/systemic administration need to be carefully determined. PMID:24409811

  6. Non-detection of C60 fullerene at two mass extinction horizons

    NASA Astrophysics Data System (ADS)

    Carrasquillo, Anthony J.; Cao, Changqun; Erwin, Douglas H.; Summons, Roger E.

    2016-03-01

    Fullerene (C60) have been reported in a number of geologic samples and, in some cases, attributed to carbonaceous materials delivered during bolide impact events. The extraction and detection of C60 poses significant analytical challenges, and some studies have been called into question due to the possibility of C60 forming in situ. Here, we extracted samples taken from the Permian-Triassic boundary section in Meishan, South China and the Cretaceous-Paleogene boundary exposed at Stevns Klint, Denmark, and analyzed the residues using a fast and reliable method for quantifying C60. Extraction of both whole rock and completely demineralized samples were completed under conditions that previously yielded C60 as well as using an optimized approach based on recent literature reports. These extracts were analyzed using mass spectrometry with the soft-ionization techniques, atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI), which have not been shown to form fullerenes in-situ. In no case were we able to detect C60, nor could we corroborate previous reports of its occurrence in these sediments, thereby challenging the utility of fullerene as a proxy for bolide impacts or mass extinction events.

  7. Exploration and characterization of new synthesis methods for C60 colloidal suspensions in water

    NASA Astrophysics Data System (ADS)

    Hilburn, Martha E.

    Buckminsterfullerene, C60, has been used in the production of several commercial products from badminton racquets and lubricants for their mechanical properties to cosmetics and even dietary supplements for their "antioxidant" properties. Multi-ton production of C60 began in 2003 encouraging serious consideration of its fate in the environment in the case of an accidental release or improper disposal. Although C60 is practically insoluble in water, it readily forms stable aqueous colloidal suspensions (termed nC60) through solvent exchange methods or long-term vigorous stirring in water. Two new solvent exchange methods for synthesizing nC60 are presented. These methods combine key advantages of multiple existing synthesis methods including high yield, narrow particle size distribution, short synthesis time, and an absence of solvents such as tetrahydrofuran that have historically caused problems in laboratory synthesized aggregates. The resulting samples are attractive candidates for use in controlled environmental impact, biological, and toxicity studies. An improved method for quantifying residual solvents in nC60 samples utilizing solid phase micro extraction gas chromatography mass spectrometry (SPME-GC-MS) is also discussed.

  8. Confinement and correlation effects in the Xe@C60 generalized oscillator strengths

    NASA Astrophysics Data System (ADS)

    Amusia, M. Ya.; Chernysheva, L. V.; Dolmatov, V. K.

    2011-12-01

    The impact of both confinement and electron correlation on generalized oscillator strengths (GOS's) of endohedral atoms, A@C60, is theoretically studied choosing the Xe@C60 4d, 5s, and 5p fast electron impact ionization as the case study. Calculations are performed in the transferred to the atom energy region beyond the 4d threshold, ω=75-175 eV. The calculation methodology combines the plane-wave Born approximation, Hartree-Fock approximation, and random-phase approximation with exchange in the presence of the C60 confinement. The confinement is modeled by a spherical δ-function-like potential as well as by a square well potential to evaluate the effect of the finite thickness of the C60 cage on the Xe@C60 GOS's. Dramatic distortion of the 4d, 5p, and 5s GOS's by the confinement is demonstrated, compared to the free atom. Considerable contributions of multipolar transitions beyond dipole transitions in the calculated GOS's are revealed, in some instances. The vitality of accounting for electron correlation in calculation of the Xe@C60 5s and 5p GOS's is shown.

  9. Preparation of C60 Nanowhiskers-SnO2 Nanocomposites and Photocatalytic Degradation of Organic Dyes.

    PubMed

    Park, Hae Soo; Ko, Weon Bae

    2015-10-01

    C60 nanowhiskers were prepared using a liquid-liquid interfacial precipitation (LLIP) method. Tin oxide (SnO2) nanoparticles were synthesized by a reaction of tin (IV) chloride pentahydrate with ammonium nitrate in an electric furnace. The C60 nanowhiskers-SnO2 nanocomposites were calcined in an electric furnace at 700 °C under an inert argon gas atmosphere for 2 h. The crystallinity, morphology and optical properties of the samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and UV-vis spectrophotometry. The photocatalytic activity of the C60 nanowhiskers-SnO2 nanocomposites in the degradation of the organic dyes, such as methylene blue, methyl orange, rhodamine B, and brilliant green, under ultraviolet light at 254 nm by UV-vis spectrophotometry was evaluated and compared with that of C60 nanowhiskers and SnO2 nanoparticles. The experimental results showed that C60 nanowhiskers-SnO2 nanocomposites exhibited remarkably higher photocatalytic degradation of organic dyes compared to C60 nanowhiskers and SnO2 nanoparticles. PMID:26726474

  10. 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