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Sample records for entire c-60 molecule

  1. 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.

  2. 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.

  3. Transport properties of individual C60-molecules

    NASA Astrophysics Data System (ADS)

    Géranton, G.; Seiler, C.; Bagrets, A.; Venkataraman, L.; Evers, F.

    2013-12-01

    Electrical and thermal transport properties of C60 molecules are investigated with density-functional-theory based calculations. These calculations suggest that the optimum contact geometry for an electrode terminated with a single-Au atom is through binding to one or two C-atoms of C60 with a tendency to promote the sp2-hybridization into an sp3-type one. Transport in these junctions is primarily through an unoccupied molecular orbital that is partly hybridized with the Au, which results in splitting the degeneracy of the lowest unoccupied molecular orbital triplet. The transmission through these junctions, however, cannot be modeled by a single Lorentzian resonance, as our results show evidence of quantum interference between an occupied and an unoccupied orbital. The interference results in a suppression of conductance around the Fermi energy. Our numerical findings are readily analyzed analytically within a simple two-level model.

  4. 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.

  5. 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.

  6. Cage structure of C60 molecules and orientational domains of two dimensional C60 arrays on a self-assembled SAM surface

    NASA Astrophysics Data System (ADS)

    Wang, Haiqing; Yang, Jinlong; Chen, D. M.; Hou, J. G.

    2000-03-01

    Scanning tunneling microscopy(STM) has been used extensively to study the C60 thin film growth on varied substrates since its discovery. Recently, some of the papers have reported the high resolution STM images showing intramolecular structures of C60 molecules. But all these images have not displayed the cage structure since the images were perturbed by the substrate-molecular interaction. A self-assembled monolayer(SAM) is an ideal substrate to support the C60 for STM investigation because it interacts very weakly with the C60 molecules but still provides good electrical conductivity for sustaining a stable tunneling condition for high resolution image. We deposited C60 onto the SAM surface at room temperature and then investigated the C60 aggregates by using a cryogenic STM. We found that the rotational motion of the C60 is frozen at 5K, and the molecules forms a new class of orientational domains that is free of defect along the domain boundaties and preserves the perfect transition symmetry across the entire 2-D array. Within each domain, all molecules adopt the same orientation rather than being in a glassy phase as in the bulk. The combination of a weak perturbing substrate and freezing of the molecular motion at low temperature has made it possible to directly image the native C60 cage structure for the first time.

  7. 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.

  8. 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.

  9. 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.

  10. 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

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

    PubMed Central

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

    2009-01-01

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

  12. Spectroscopic observations of the displacement dynamics of physically adsorbed molecules-CO on C60

    NASA Astrophysics Data System (ADS)

    Yuan, Chunqing; Yates, John T.

    2016-10-01

    In this paper, we observed physically adsorbed CO molecules on C60 surface being displaced by impinging noble gas atoms (He, Ne, Ar, Kr), either through a dynamic displacement process or an exothermic replacement process, depending on their adsorption energies. This displacement mechanism could shift from one to the other depending on the surface coverage and temperature. Furthermore, rotational energy of the impinging molecules may also contribute to the dynamic displacement process by supplying additional energy.

  13. Small Molecules in C60 and C70: Which Complexes Could Be Stabilized?

    PubMed

    Korona, Tatiana; Dodziuk, Helena

    2011-05-10

    The recent syntheses of complexes involving some small molecules in opened fullerenes and those of hydrogen molecule(s) in C60 and C70 are accompanied in the literature by numerous computations for endohedral fullerene complexes which cope with the problem of the stability of these complexes. In this contribution, stabilization energies of endohedral complexes of C60 and C70 with H2, N2, CO, HCN, H2O, H2S, NH3, CH4, CO2, C2H2, H2CO, and CH3OH guests have been estimated using symmetry-adapted perturbation theory, which, contrary to the standard DFT and some other approaches, correctly describes the dispersion contribution of the host-guest interactions. On the basis of these calculations, the endohedral complexes with all these guests were found stable in the larger fullerene, while the C60 cage was found too small to host the latter four molecules. Except for H2 and H2CO, a stabilization effect for most guests in the C60 cage is about 30 kJ/mol. For H2 and H2O guests, a typical supramolecular effect is observed; namely, the stabilization in the smaller cage is equal to or larger than that in the larger C70 host. Except for the water molecule where the induction interaction plays a non-negligible role, in all complexes the main stabilization effect comes from the dispersion interaction. The information on the stability of hypothetical endohedral fullerene complexes and physical factors contributing to it can be of importance in designing future experiments contributing to their applications.

  14. Direct Observation of a Gas Molecule (H2, Ar) Swallowed by C60

    SciTech Connect

    Sawa, H.; Kakiuchi, T.; Wakabayashi, Y.; Murata, Y.; Murata, M.; Komatsu, K.; Yakigaya, K.; Takagi, H.; Dragoe, N.

    2007-01-19

    Various types of endohedral fullerene complexes are known to date. The well known metallofullerenes are generally produced by arc-discharge method, but the use of such extremely drastic conditions is apparently not suitable for encapsulation of unstable molecules or gases. We recently succeeded in incorporation of a H2 molecule or an Ar atom in 100% into a C60. In order to observe the endohedral gas molecule directly, the X-ray diffraction analysis using synchrotron radiation were carried out. We observed a gas molecule encapsulated in each fullerene cage using structure analysis and the maximum entropy method. These gas molecules are floating inside of the hollow cavities and are completely isolated from the outside.

  15. Self-interaction corrections applied to Mg-porphyrin, C60, and pentacene molecules

    NASA Astrophysics Data System (ADS)

    Pederson, Mark R.; Baruah, Tunna; Kao, Der-you; Basurto, Luis

    2016-04-01

    We have applied a recently developed method to incorporate the self-interaction correction through Fermi orbitals to Mg-porphyrin, C60, and pentacene molecules. The Fermi-Löwdin orbitals are localized and unitarily invariant to the Kohn-Sham orbitals from which they are constructed. The self-interaction-corrected energy is obtained variationally leading to an optimum set of Fermi-Löwdin orbitals (orthonormalized Fermi orbitals) that gives the minimum energy. A Fermi orbital, by definition, is dependent on a certain point which is referred to as the descriptor position. The degree to which the initial choice of descriptor positions influences the variational approach to the minimum and the complexity of the energy landscape as a function of Fermi-orbital descriptors is examined in detail for Mg-porphyrin. The applications presented here also demonstrate that the method can be applied to larger molecular systems containing a few hundred electrons. The atomization energy of the C60 molecule within the Fermi-Löwdin-orbital self-interaction-correction approach is significantly improved compared to local density approximation in the Perdew-Wang 92 functional and generalized gradient approximation of Perdew-Burke-Ernzerhof functionals. The eigenvalues of the highest occupied molecular orbitals show qualitative improvement.

  16. Specific features of the glass transition in C60 fullerite saturated with carbon monoxide molecules: Photoluminescence studies

    NASA Astrophysics Data System (ADS)

    Zinoviev, P. V.; Zoryansky, V. N.; Stetsenko, Yu. E.; Danchuk, V. V.

    2016-02-01

    Low temperature (20-230 K) spectral-luminescence studies were conducted on C60 fullerite saturated with carbon monoxide in a physisorption regime. Substantial changes in the photoluminescence characteristics of C60-CO solutions with different impurity concentrations were found already for short intercalation times. Strong dependence of the CO solubility on the saturation temperature was revealed by analyzing the contribution of "deep X-traps" to the luminescence. Furthermore, it was found that filling of the octahedral voids by CO molecules occurs with a lower gradient of the impurity distribution into the bulk C60 crystals as compared with N2. The temperature dependences of the integral emission intensity for the samples with different concentrations of carbon monoxide were studied. For the first time, using the spectral-luminescence method, it was revealed that CO molecules, in contrast to H2 and N2, exhibit a significant effect on the formation of the orientational glass and the rotational dynamics of C60 molecules. Within the model of the transfer of electronic excitation in C60 crystals, the effect of polar CO molecules on the reorientation of C60 molecules and the change in the nature of their rotation in concentrated C60-CO solutions, leading to the observed strong shift of the temperatures of orientational Tc and glass Tg transitions to lower temperatures accompanied by "blurring" of the transition boundaries, were explained.

  17. Theoretical investigation of endohedral complexes of Si and Ge with C60 molecule

    NASA Astrophysics Data System (ADS)

    Umran, Nibras Mossa; Kumar, Ranjan

    2014-03-01

    The electronic and magnetic properties of Si and Ge doped C60 fullerene are investigated with ab initio density functional theory calculations. In endohedral Sin (n=1-10) and Gen (1-9) doped C60 complexes we have seen that Si and Ge doped complexes are stable up to 9 and 4 atoms, respectively. We have also investigated binding energy and ionization potential of the endohedral fullerene C60. Endohedral fullerenes have been found to be more chemically reactive. Mullikan charge analysis shows the presence of the magnetic moment in these systems.

  18. Mercator maps of orientations of a C60 molecule in single-walled nanotubes with distinct radii

    SciTech Connect

    Michel, K.H.; Verberck, B.; Nikolaev, A.V.

    2005-09-27

    We study the confinement of a C60 molecule encapsulated in a cylindrical nanotube as a function of the tube radius. Drawing the Mercator maps of the potential, we find two distinct molecular orientations; for tubes with small radii, RT < or approx. 7 A, a fivefold axis of the molecule coincides with the tube long axis, for larger radii, RT > or approx. 8 A, a threefold axis of the molecule coincides with the tube long axis. These different orientations are caused by the relative importance of the repulsive and the attractive parts of the van der Waals potentials of the molecule with the tube wall for small and large tubes respectively. Experimental evidence is provided by the apparent splitting of Ag modes of the C60 molecule in resonant Raman scattering.

  19. Features of self-aggregation of C60 molecules in toluene prepared by different methods

    NASA Astrophysics Data System (ADS)

    Makhmanov, Urol; Ismailova, Oksana; Kokhkharov, Abdulmutallib; Zakhidov, Erkin; Bakhramov, Sagdilla

    2016-05-01

    Structural and dimensional features of C60 aggregates in toluene solution prepared in two different ways - equilibrium and strongly non-equilibrium - were studied by high-resolution transmission electron microscopy and atomic-force microscopy methods. It was found that in solutions prepared by the non-equilibrium method (stirring of solution of C60 by a mechanical rotator), large quasispherical aggregates (with a diameter of up to ∼ 380 ± 20 nm) of nanoporous structure with fractal size D ≈ 2.13 were synthesized. In the case of solutions C60, which were prepared by the equilibrium method (without the use of external mechanical influences on solution), the formation of densely packed monomolecular fullerene aggregates with a diameter of not more than 50 nm was observed.

  20. Room-temperature repositioning of individual C60 molecules at Cu steps: Operation of a molecular counting device

    NASA Astrophysics Data System (ADS)

    Cuberes, M. T.; Schlittler, R. R.; Gimzewski, J. K.

    1996-11-01

    C60 molecules absorbed on a monoatomic Cu step have been reversibly repositioned at room temperature with the tip of a scanning tunneling microscope by performing controlled displacements along the step direction. We demonstrate the feasibility of building an abacus on the nanometer scale using single molecules as ``counters,'' Cu monoatomic steps as ``rods'' that constrain the molecular motion to one dimension, and the scanning tunneling microscope as an ``actuator'' for counting operations.

  1. Diffusion and self-assembly of C60 molecules on monolayer graphyne sheets

    PubMed Central

    Ozmaian, Masoumeh; Fathizadeh, Arman; Jalalvand, Morteza; Ejtehadi, Mohammad Reza; Allaei, S. Mehdi Vaez

    2016-01-01

    The motion of a fullerene (C60) on 5 different types of graphyne is studied by all-atom molecular dynamics simulations and compared with former studies on the motion of C60 on graphene. The motion shows a diffusive behavior which consists of either a continuous motion or discrete movements between trapping sites depending on the type of the graphyne sheet. For graphyne-4 and graphyne-5, fullerenes could detach from the surface of the graphyne sheet at room temperature which was not reported for similar cases on graphene sheets. Collective motion of a group of fullerenes interacting with a graphyne studied and it is shown that fullerenes exhibit stable assemblies. Depending on the type of graphyne, these assemblies can have either single or double layers. The mobility of the assembled structures is also dependent on the type of the graphyne sheet. The observed properties of the motion suggests novel applications for the complexes of fullerene and monolayer graphynes. PMID:26912386

  2. High-resolution imaging of C60 molecules using tuning-fork-based non-contact atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Pawlak, R.; Kawai, S.; Fremy, S.; Glatzel, T.; Meyer, E.

    2012-02-01

    Recent advances in non-contact atomic force microscopy (nc-AFM) have led to the possibility of achieving unprecedented resolution within molecular structures, accomplished by probing short-range repulsive interaction forces. Here we investigate C60 molecules adsorbed on KBr(111) and Cu(111) by tuning-fork-based nc-AFM. First, measurements of C60 deposited on KBr(001) were conducted in cryogenic conditions revealing highly resolved nc-AFM images of the self-assembly. Using constant-frequency shift mode as well as three-dimensional spectroscopic measurements, we observe that the relatively weak molecule-substrate interaction generally leads to the disruption of molecular assembled structures when the tip is probing the short-range force regime. This particular issue hindered us in resolving the chemical structure of this molecule on the KBr surface. To obtain a better anchoring of C60 molecules, nc-AFM measurements were performed on Cu(111). Sub-molecular resolutions within the molecules was achieved which allowed a direct and unambiguous visualization of their orientations on the supporting substrate. Furthermore, three-dimensional spectroscopic measurements of simultaneous force and current have been performed above the single molecules giving information of the C60 molecular orientation as well as its local conductivity. We further discuss the different imaging modes in nc-AFM such as constant-frequency shift nc-AFM, constant-height nc-AFM and constant-current nc-AFM as well as three-dimensional spectroscopic measurement (3D-DFS) employed to achieve such resolution at the sub-molecular scale.

  3. High-resolution imaging of C60 molecules using tuning-fork-based non-contact atomic force microscopy.

    PubMed

    Pawlak, R; Kawai, S; Fremy, S; Glatzel, T; Meyer, E

    2012-02-29

    Recent advances in non-contact atomic force microscopy (nc-AFM) have led to the possibility of achieving unprecedented resolution within molecular structures, accomplished by probing short-range repulsive interaction forces. Here we investigate C(60) molecules adsorbed on KBr(111) and Cu(111) by tuning-fork-based nc-AFM. First, measurements of C(60) deposited on KBr(001) were conducted in cryogenic conditions revealing highly resolved nc-AFM images of the self-assembly. Using constant-frequency shift mode as well as three-dimensional spectroscopic measurements, we observe that the relatively weak molecule-substrate interaction generally leads to the disruption of molecular assembled structures when the tip is probing the short-range force regime. This particular issue hindered us in resolving the chemical structure of this molecule on the KBr surface. To obtain a better anchoring of C(60) molecules, nc-AFM measurements were performed on Cu(111). Sub-molecular resolutions within the molecules was achieved which allowed a direct and unambiguous visualization of their orientations on the supporting substrate. Furthermore, three-dimensional spectroscopic measurements of simultaneous force and current have been performed above the single molecules giving information of the C(60) molecular orientation as well as its local conductivity. We further discuss the different imaging modes in nc-AFM such as constant-frequency shift nc-AFM, constant-height nc-AFM and constant-current nc-AFM as well as three-dimensional spectroscopic measurement (3D-DFS) employed to achieve such resolution at the sub-molecular scale.

  4. Low-temperature dynamics of matrix isolated methane molecules in fullerite C60: The heat capacity, isotope effects

    NASA Astrophysics Data System (ADS)

    Bagatskii, M. I.; Manzhelii, V. G.; Sumarokov, V. V.; Dolbin, A. V.; Barabashko, M. S.; Sundqvist, B.

    2014-08-01

    The heat capacity of the interstitial solid solution (CH4)0.4C60 has been investigated in the temperature interval 1.4-120 K. The contribution of CH4 molecules to the heat capacity of the solution has been separated. The contributions of CH4 and CD4 molecules to the heat capacity of the solutions (CH4)0.40C60 and (CD4)0.40C60 have been compared. It is found that above 90 K the character of the rotational motion of CH4 and CD4 molecules changes from libration to hindered rotation. In the interval 14-35 K the heat capacities of CH4 and CD4 molecules are satisfactorily described by contributions of the translational and libration vibrations, as well as the tunnel rotation for the equilibrium distribution of the nuclear spin species. The isotope effect is due to mainly, the difference in the frequencies of local translational and libration vibrations of molecules CH4 and CD4. The contribution of the tunnel rotation of the CH4 and CD4 molecules to the heat capacity is dominant below 8 K. The isotopic effect is caused by the difference between both the conversion rates and the rotational spectra of the nuclear spin species of CH4 and CD4 molecules. The conversion rate of CH4 molecules is several times lower than that of CD4 ones. Weak features observed in the curves of temperature dependencies of the heat capacity of CH4 and CD4 molecules near 6 and 8 K, respectively, are most likely a manifestation of first-order polyamorphic phase transitions in the orientational glasses of these solutions.

  5. Chemistry and temperature-assisted dehydrogenation of C60H30 molecules on TiO2(110) surfaces.

    PubMed

    Sánchez-Sánchez, Carlos; Martínez, José Ignacio; Lanzilotto, Valeria; Biddau, Giulio; Gómez-Lor, Berta; Pérez, Rubén; Floreano, Luca; López, María Francisca; Martín-Gago, José Ángel

    2013-11-21

    The thermal induced on-surface chemistry of large polycyclic aromatic hydrocarbons (PAHs) deposited on dielectric substrates is very rich and complex. We evidence temperature-assisted (cyclo)dehydrogenation reactions for C60H30 molecules and the subsequent bottom-up formation of assembled nanostructures, such as nanodomes, on the TiO2(110) surface. To this aim we have deposited, under ultra-high vacuum, a submonolayer coverage of C60H30 and studied, by a combination of experimental techniques (STM, XPS and NEXAFS) and theoretical methods, the different chemical on-surface interaction stages induced by the increasing temperature. We show that room temperature adsorbed molecules exhibit a weak interaction and freely diffuse on the surface, as previously reported for other aromatics. Nevertheless, a slight annealing induces a transition from this (meta)stable configuration into chemisorbed molecules. This adsorbate-surface interaction deforms the C60H30 molecular structure and quenches surface diffusion. Higher annealing temperatures lead to partial dehydrogenation, in which the molecule loses some of the hydrogen atoms and LUMO levels spread in the gap inducing a net total energy gain. Further annealing, up to around 750 K, leads to complete dehydrogenation. At these temperatures the fully dehydrogenated molecules link between them in a bottom-up coupling, forming nanodomes or fullerene-like monodisperse species readily on the dielectric surface. This work opens the door to the use of on-surface chemistry to generate new bottom-up tailored structures directly on high-K dielectric surfaces. PMID:24071968

  6. Atomically resolved orientational ordering of C60 molecules on epitaxial graphene on Cu(111)

    NASA Astrophysics Data System (ADS)

    Jung, Minbok; Shin, Dongbin; Sohn, So-Dam; Kwon, Soon-Yong; Park, Noejung; Shin, Hyung-Joon

    2014-09-01

    A detailed understanding of interactions between molecules and graphene is one of the key issues for tailoring the properties of graphene-based molecular devices, because the electronic and structural properties of molecular layers on surfaces are determined by intermolecular and molecule-substrate interactions. Here, we present the atomically resolved experimental measurements of the self-assembled fullerene molecules on single-layer graphene on Cu(111). Fullerene molecules form a (4 × 4) superstructure on graphene/Cu(111), revealing only single molecular orientation. We can resolve the exact adsorption site and the configuration of fullerene by means of low-temperature scanning tunnelling microscopy (LT-STM) and density functional theory (DFT) calculations. The adsorption orientation can be explained in terms of the competition between intermolecular interactions and molecule-substrate interactions, where strong Coulomb interactions among the fullerenes determine the in-plane orientation of the fullerene. Our results provide important implications for developing carbon-based organic devices using a graphene template in the future.A detailed understanding of interactions between molecules and graphene is one of the key issues for tailoring the properties of graphene-based molecular devices, because the electronic and structural properties of molecular layers on surfaces are determined by intermolecular and molecule-substrate interactions. Here, we present the atomically resolved experimental measurements of the self-assembled fullerene molecules on single-layer graphene on Cu(111). Fullerene molecules form a (4 × 4) superstructure on graphene/Cu(111), revealing only single molecular orientation. We can resolve the exact adsorption site and the configuration of fullerene by means of low-temperature scanning tunnelling microscopy (LT-STM) and density functional theory (DFT) calculations. The adsorption orientation can be explained in terms of the competition

  7. 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.

  8. 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

  9. 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

  10. Adsorption of sodium and cesium on aggregates of C60

    NASA Astrophysics Data System (ADS)

    Harnisch, Martina; Daxner, Matthias; Scheier, Paul; Echt, Olof

    2016-09-01

    We explore the formation of C60 sodium and C60 cesium complexes in superfluid helium nanodroplets. Anomalies in mass spectra of these doped droplets reveal anomalies in the stability of ions. (C60) m Cs+ n ions ( m ≤ 6) are particularly abundant if they contain n = 6 m + 1 cesium atoms; (C60) m Cs2+ n dications ( m ≤ 3 or 5) are abundant if n = 6 m + 2. These findings are consistent with the notion that alkali metal atoms (A) transfer their valence electrons into the three-fold degenerate lowest unoccupied orbital of C60, resulting in particularly stable C60A6 building blocks. However, (C60) 4CsCs2+ n dications display an entirely different pattern; instead of an expected anomaly at n = 6 × 4 + 2 = 26 we observe a strong odd-even alternation starting at n = 6. Also surprising is the effect of adding one H2O or CO2 molecule to (C60) m Cs n mono- or dications; anomalies shift by two units as if the impurity were acting as an acceptor for two valence electrons from the alkali metal atoms.

  11. C60 fullerene binding to DNA

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  12. 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.

  13. The dipolar endofullerene HF@C60.

    PubMed

    Krachmalnicoff, Andrea; Bounds, Richard; Mamone, Salvatore; Alom, Shamim; Concistrè, Maria; Meier, Benno; Kouřil, Karel; Light, Mark E; Johnson, Mark R; Rols, Stéphane; Horsewill, Anthony J; Shugai, Anna; Nagel, Urmas; Rõõm, Toomas; Carravetta, Marina; Levitt, Malcolm H; Whitby, Richard J

    2016-10-01

    The cavity inside fullerenes provides a unique environment for the study of isolated atoms and molecules. We report the encapsulation of hydrogen fluoride inside C60 using molecular surgery to give the endohedral fullerene HF@C60. The key synthetic step is the closure of the open fullerene cage with the escape of HF minimized. The encapsulated HF molecule moves freely inside the cage and exhibits quantization of its translational and rotational degrees of freedom, as revealed by inelastic neutron scattering and infrared spectroscopy. The rotational and vibrational constants of the encapsulated HF molecules were found to be redshifted relative to free HF. The NMR spectra display a large (1)H-(19)F J coupling typical of an isolated species. The dipole moment of HF@C60 was estimated from the temperature dependence of the dielectric constant at cryogenic temperatures and showed that the cage shields around 75% of the HF dipole. PMID:27657872

  14. The dipolar endofullerene HF@C60

    NASA Astrophysics Data System (ADS)

    Krachmalnicoff, Andrea; Bounds, Richard; Mamone, Salvatore; Alom, Shamim; Concistrè, Maria; Meier, Benno; Kouřil, Karel; Light, Mark E.; Johnson, Mark R.; Rols, Stéphane; Horsewill, Anthony J.; Shugai, Anna; Nagel, Urmas; Rõõm, Toomas; Carravetta, Marina; Levitt, Malcolm H.; Whitby, Richard J.

    2016-10-01

    The cavity inside fullerenes provides a unique environment for the study of isolated atoms and molecules. We report the encapsulation of hydrogen fluoride inside C60 using molecular surgery to give the endohedral fullerene HF@C60. The key synthetic step is the closure of the open fullerene cage with the escape of HF minimized. The encapsulated HF molecule moves freely inside the cage and exhibits quantization of its translational and rotational degrees of freedom, as revealed by inelastic neutron scattering and infrared spectroscopy. The rotational and vibrational constants of the encapsulated HF molecules were found to be redshifted relative to free HF. The NMR spectra display a large 1H-19F J coupling typical of an isolated species. The dipole moment of HF@C60 was estimated from the temperature dependence of the dielectric constant at cryogenic temperatures and showed that the cage shields around 75% of the HF dipole.

  15. 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.

  16. Solvent friction effects propagate over the entire protein molecule through low-frequency collective modes.

    PubMed

    Moritsugu, Kei; Kidera, Akinori; Smith, Jeremy C

    2014-07-24

    Protein solvation dynamics has been investigated using atom-dependent Langevin friction coefficients derived directly from molecular dynamics (MD) simulations. To determine the effect of solvation on the atomic friction coefficients, solution and vacuum MD simulations were performed for lysozyme and staphylococcal nuclease and analyzed by Langevin mode analysis. The coefficients thus derived are roughly correlated with the atomic solvent-accessible surface area (ASA), as expected from the fact that friction occurs as the result of collisions with solvent molecules. However, a considerable number of atoms with higher friction coefficients are found inside the core region. Hence, the influence of solvent friction propagates into the protein core. The internal coefficients have large contributions from the low-frequency modes, yielding a simple picture of the surface-to-core long-range damping via solvation governed by collective low-frequency modes. To make use of these findings in implicit-solvent modeling, we compare the all-atom friction results with those obtained using Langevin dynamics (LD) with two empirical representations: the constant-friction and the ASA-dependent (Pastor-Karplus) friction models. The constant-friction model overestimates the core and underestimates the surface damping whereas the ASA-dependent friction model, which damps protein atoms only on the solvent-accessible surface, reproduces well the friction coefficients for both the surface and core regions observed in the explicit-solvent MD simulations. Therefore, in LD simulation, the solvent friction coefficients should be imposed only on the protein surface. PMID:24999844

  17. Solvent friction effects propagate over the entire protein molecule through low-frequency collective modes.

    PubMed

    Moritsugu, Kei; Kidera, Akinori; Smith, Jeremy C

    2014-07-24

    Protein solvation dynamics has been investigated using atom-dependent Langevin friction coefficients derived directly from molecular dynamics (MD) simulations. To determine the effect of solvation on the atomic friction coefficients, solution and vacuum MD simulations were performed for lysozyme and staphylococcal nuclease and analyzed by Langevin mode analysis. The coefficients thus derived are roughly correlated with the atomic solvent-accessible surface area (ASA), as expected from the fact that friction occurs as the result of collisions with solvent molecules. However, a considerable number of atoms with higher friction coefficients are found inside the core region. Hence, the influence of solvent friction propagates into the protein core. The internal coefficients have large contributions from the low-frequency modes, yielding a simple picture of the surface-to-core long-range damping via solvation governed by collective low-frequency modes. To make use of these findings in implicit-solvent modeling, we compare the all-atom friction results with those obtained using Langevin dynamics (LD) with two empirical representations: the constant-friction and the ASA-dependent (Pastor-Karplus) friction models. The constant-friction model overestimates the core and underestimates the surface damping whereas the ASA-dependent friction model, which damps protein atoms only on the solvent-accessible surface, reproduces well the friction coefficients for both the surface and core regions observed in the explicit-solvent MD simulations. Therefore, in LD simulation, the solvent friction coefficients should be imposed only on the protein surface.

  18. 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

  19. Electronic structure of a linear C 60 polymer

    NASA Astrophysics Data System (ADS)

    Tanaka, Kazuyoshi; Matsuura, Yukihito; Oshima, Yoshiaki; Yamabe, Tokio; Asai, Yoshihiro; Tokumoto, Madoka

    1995-01-01

    The electronic structure of a C 60-polymer chain was studied based on the tight-binding calculation including both σ and π electrons. The C 60-polymer turns out semiconducting with a finite band gap ( ca 1.1 eV) and its lowest unoccupied (LU) band is no more degenerate. The LU bandwidth of this polymer is generally smaller than that of A 3C 60 by more than one order of magnitude around the Fermi level assuring that C 60-1-polymer ( o-RbC 60) is a strongly correlated system ( {U}/{t ≫ 1}) and can have the antiferromagnetic ground state. Such reduction of t comes from the cut of π-conjugation on the surface of C 60 molecule by the bridging.

  20. 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

  1. Junction characteristics of C 60/polycarbonate blend on Si substrate

    NASA Astrophysics Data System (ADS)

    Sharma, S. S.; Tripathi, B.; Singh, M.; Bhatnagar, D.; Vijay, Y. K.

    2009-05-01

    We report a study of the interface between fullerene (C 60) doped polycarbonate (PC) blends and n-type Si substrate. C 60 is usually an electron acceptor in interpenetrated networks and an electron transport in photovoltaic cells. We have studied that the guest-host approach to prepare C 60 doped polycarbonate blend. In this article, we report the I-V characteristics of C 60 doped polycarbonate/n-type Si junction and the annealing effect on these characteristics. In this junction, a nanocomposite of organic semiconductor fullerene (C 60), used as the active medium, with an inert polycarbonate matrix was spin coated on n-type Si substrate. We found that the C 60 shows the junction characteristics with n-type Si substrate. The knee voltage and dynamic resistance varies with concentration of C 60 as well as temperature. Ellipsometry studies showed the annealing effect on the refractive index and thickness of C 60 doped polycarbonate blend on n-type Si substrate. The optical micrographs show that fullerene (C 60) is spherical molecule and it is blend in the form of crystallites having size of micron order.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. Probing the interaction at the C 60-SiC nanomesh interface

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Chen, Shi; Zhang, Hong Liang; Xu, Hai; Qi, Dong Chen; Gao, Xing Yu; Loh, Kian Ping; Wee, Andrew Thye Shen

    2007-07-01

    Synchrotron-based high-resolution photoemission spectroscopy (PES) and in situ scanning tunneling microscopy (STM) are used to investigate the interaction at the C 60-SiC nanomesh interface during the sequential deposition and subsequent desorption of C 60 molecules. A weak charge transfer occurs at the C 60-nanomesh interface, involving electrons transferring from nanomesh to C 60 overlayer. The interface interaction originated from the weak charge transfer at the C 60-nanomesh interface is stronger than C 60 intermolecular interaction (e.g., van-der-Waals force), facilitating the layer-by-layer growth for the first two layers of C 60 on SiC nanomesh. The highly corrugated nanomesh surface results in an anisotropic diffusion and high diffusion barrier of C 60 on top, and thereby leads to the formation of irregularly shaped C 60 islands under submonolayer condition. In contrast, C 60 diffusion on HOPG and Ag(1 1 1) surfaces is rather isotropic, resulting in the formation of hexagonally shaped C 60 islands with smooth domain boundaries. STM results show the partial desorption of C 60 molecules from the SiC nanomesh surface after annealing the 1 ML C 60 sample (complete wetting layer of C 60 on SiC nanomesh) at around 150 °C for 20 min. Thorough desorption of C 60 molecules and full recovery of the clean SiC nanomesh are observed after annealing at around 200 °C for 20 min. In situ PES and STM experiments clearly demonstrate that C 60 adsorption and desorption processes do not affect the underlying SiC nanomesh structure, revealing its thermal stability and chemical inertness to C 60 molecules.

  7. 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.

  8. 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

  9. 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).

  10. Entrapping of exohedral metallofullerenes in carbon nanotubes: (CsC60)n@SWNT nano-peapods.

    PubMed

    Sun, Bao-Yun; Sato, Yuta; Suenaga, Kazutomo; Okazaki, Toshiya; Kishi, Naoki; Sugai, Toshiki; Bandow, Shunji; Iijima, Sumio; Shinohara, Hisanori

    2005-12-28

    Exohedral C60-based metallofullerenes, CsC60, have been synthesized and successfully encapsulated into single-wall carbon nanotubes (SWNTs) in high yield by reducing C60 molecules into anions. High-resolution transmission electron microscopy (HRTEM) images and in situ electron energy loss spectroscopy (EELS) indicate that Cs atoms and C60 molecules align within SWNTs as CsC60 exohedral metallofullerenes, and that the formal charge state of encaged CsC60 is expressed as Cs+1C60-1. The present peapods with the exohedral metallofullerenes provide a new insight and the possibility to fine-tune the electronic and transport properties of carbon nanotubes.

  11. 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.

  12. Semiconductor nanocrystals photosensitize C60 crystals.

    PubMed

    Biebersdorf, Andreas; Dietmüller, Roland; Susha, Andrei S; Rogach, Andrey L; Poznyak, Sergey K; Talapin, Dmitri V; Weller, Horst; Klar, Thomas A; Feldmann, Jochen

    2006-07-01

    Semiconductor nanocrystals (SCNCs) made of CdSe, CdTe, and InP are used to photosensitize needlelike C(60) crystals. The photocurrent is increased by up to 3 orders of magnitude as compared with C(60) crystals without SCNCs. The photocurrent spectrum can be tuned precisely by the SCNC size and material, rendering the SCNC-functionalized C(60) crystals an excellent material for spectrally tuneable photodetectors. We explain the increased photocurrent as a result of photoexcited electrons transferring from the SCNCs to the C(60) crystals and causing photoconductivity, while the complementary holes remain trapped in the SCNCs.

  13. 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.

  14. 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.

  15. 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

  16. 15 CFR 8c.60 - Communications.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 15 Commerce and Foreign Trade 1 2014-01-01 2014-01-01 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...

  17. 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...

  18. 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...

  19. 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...

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Angular resolved photoionization of C60 by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Li, Hui; Wang, Zhenhua; Suessmann, Frederik; Zherebtsov, Sergey; Skruszewicz, Slawomir; Tiggesbaeumker, Josef; Fennel, Thomas; Meiwes-Broer, Karl-Heinz; Cocke, C.; Kling, Matthias; JRM laboratory, Kansas State University Team; University of Rostock Collaboration; Max-Planck InstitutQuantumoptik Collaboration

    2013-03-01

    Neutral C60 molecules are ionized by intense femtosecond laser pulses around the wavelength of 800 nm with pulse durations 4 fs and 30 fs. We measure photoelectrons utilizing velocity-map imaging (VMI) and analyze the photoelectron angular distributions. For particular photoelectron energies, these distributions might reflect the excitation and ionization of superatomic molecular orbitals (SAMOs) which have been theoretically predicted and only recently experimentally observed. SAMOs arise from the hollow core spherical structures of the C60 molecules and differ from Rydberg states of C60 by their potential to exhibit electron density within the C60 cage. We have recorded the carrier envelope phase (CEP) dependence of the electron emission for 4 fs pulses using single shot CEP-tagging. The CEP-dependent asymmetry in the electron emission is observed to strongly depend on the laser polarization. Furthermore, the amplitudes and phases of the CEP-dependent electron emission are analyzed and show that thermal electron emission can be avoided enabling a more direct comparison to theory.

  6. 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.

  7. 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.

  8. Mechanism of complexation of the phenothiazine dye methylene blue with fullerene C60

    NASA Astrophysics Data System (ADS)

    Buchelnikov, A. S.; Kostyukov, V. V.; Yevstigneev, M. P.; Prylutskyy, Yu. I.

    2013-04-01

    The complexation of fullerene C60 with the aromatic dye methylene blue (MB) in aqueous solution was studied. Spectrophotometric titration revealed a reasonably strong interaction between C60 and MB molecules with an equilibrium constant K = 2110 L/mol and the binding of up to five dye molecules with the surface of C60. The energy analysis of the MB-C60 system showed that the intermolecular and hydrophobic interactions were dominant in the energy profile of the complexation, and while the electrostatic factor played an insignificant role.

  9. 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.

  10. 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

  11. Temperature Evolution of Quasi-one-dimensional C60 Nanostructures on Rippled Graphene

    PubMed Central

    Chen, Chuanhui; Zheng, Husong; Mills, Adam; Heflin, James R.; Tao, Chenggang

    2015-01-01

    We report the preparation of novel quasi-one-dimensional (quasi-1D) C60 nanostructures on rippled graphene. Through careful control of the subtle balance between the linear periodic potential of rippled graphene and the C60 surface mobility, we demonstrate that C60 molecules can be arranged into a quasi-1D C60 chain structure with widths of two to three molecules. At a higher annealing temperature, the quasi-1D chain structure transitions to a more compact hexagonal close packed quasi-1D stripe structure. This first experimental realization of quasi-1D C60 structures on graphene may pave a way for fabricating new C60/graphene hybrid structures for future applications in electronics, spintronics and quantum information. PMID:26391054

  12. Temperature Evolution of Quasi-one-dimensional C60 Nanostructures on Rippled Graphene

    NASA Astrophysics Data System (ADS)

    Chen, Chuanhui; Zheng, Husong; Mills, Adam; Heflin, James R.; Tao, Chenggang

    2015-09-01

    We report the preparation of novel quasi-one-dimensional (quasi-1D) C60 nanostructures on rippled graphene. Through careful control of the subtle balance between the linear periodic potential of rippled graphene and the C60 surface mobility, we demonstrate that C60 molecules can be arranged into a quasi-1D C60 chain structure with widths of two to three molecules. At a higher annealing temperature, the quasi-1D chain structure transitions to a more compact hexagonal close packed quasi-1D stripe structure. This first experimental realization of quasi-1D C60 structures on graphene may pave a way for fabricating new C60/graphene hybrid structures for future applications in electronics, spintronics and quantum information.

  13. Continuous symmetry of C60 fullerene and its derivatives.

    PubMed

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

    2011-04-21

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

  14. Intercalation of alcohols methanol, ethanol and isopropanol into fullerene C 60 lattice

    NASA Astrophysics Data System (ADS)

    Vojinovic-Miloradov, Mirjana; Lazar, Dusan; Djordjevic, Aleksandar; Adamov, Jasna; Milic-Djordjevic, Vukosava; Vujic, Djura; Odavic-Josic, Jelica; Koruga, Djuro

    1998-11-01

    New non-covalent intermolecular fullerene system containing discrete C 60 and alcohol molecules have been prepared from the saturated solutions of fullerene in toluene with ethanol, methanol and isopropanol. The formation of intercalates with alcohols R-OH⊂C 60 (R=C 1-C 3) has not been described in the literature yet. Pure intercalates R-OH⊂C 60 were obtained in the direct synthesis of C 60 in toluene with R-OH (methanol, ethanol and isopropanol). UV and IR spectra of C 2H 5-OH⊂C 60 and C 3H 7-OH⊂C 60 showed no change compared to the pristine C 60. However, IR spectrum of the methanol intercalate contains additional peaks at 2920 and 3400 cm -1. There has also been no change in their diffraction images concerning the d-values (the diffractograms of powder), indicating that the compounds are isostructural with C 60. The appearance of a very intensive d 101 peak in the powder diffractogram of the methanol derivative indicates that stacking disorder is probably eliminated, which can be correlated to the additional bands in IR spectrum. Intermolecular interactions (of the type that exists in supramolecular systems) between C 60 and alcohol molecules C 1-C 3 exist because of the specific energy surfaces of C 60 molecule (the consequence of its electronic, vibrational and rotational properties) and the size, inductive, spatial and geometrical characteristics of intercalants (alcohols). The size and shape of the alcohols which form intercalates with C 60 is such that they nicely fit within the intermolecular distances of C 60 molecules (0.293 nm) in a hexagonal lattice.

  15. 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.

  16. 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.

  17. 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.

  18. Drift velocity of C(60)(+) in gases follows rarefied gas dynamics.

    PubMed

    Nanbu, K; Wakayama, G

    2001-06-01

    The drift velocities of C(60)(+) in He, Ne, Ar, and Kr were found to be estimated with high accuracy using the drag coefficient of a solid body in free molecule flow. That is, massive C(60)(+) behaves in gases as if it were a large classical body.

  19. 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.

  20. 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.

  1. 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.

  2. Vertical crystallization of C60 nanowires by solvent vapor annealing process.

    PubMed

    Kim, Jungah; Park, Chibeom; Park, Ji Eun; Chu, Kwangho; Choi, Hee Cheul

    2013-10-22

    We report that C60 molecules are spontaneously crystallized into vertical nanowires by the solvent vapor annealing (SVA) process. C60 molecules have been known to be assembled into wire-like crystals by simply dropping and drying C60 solutions in m-xylene on a solid substrate. By the drop-drying process, C60 nanowires have been mostly grown laterally on a solid substrate, as the major force applied to the droplet during the drying process is parallel to the substrate. On the other hand, the SVA process seems to provide an ideal environment under which the direction of the dominant drying force of a droplet becomes vertical. When a thermally evaporated C60 film is exposed to m-xylene solvent vapor under controlled SVA environments at room temperature, C60 molecules are found to be crystallized into vertical nanowires. The effect of solvent vapor pressure on the vertical growth of C60 nanowire is examined by comparative studies using mesitylene and 1,3-dichlorobenzene. The versatility of the SVA process for the growth of vertical organic nanostructures is further demonstrated by the successful formations of vertically grown C60 2D disks and 5,7,12,14-pentacenetetrone anisotropic crystals by employing carbon tetrachloride and toluene solvent vapors, respectively.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. First principles study on the electronic transport properties of C60 and B80 molecular bridges

    NASA Astrophysics Data System (ADS)

    Zheng, X. H.; Hao, H.; Lan, J.; Wang, X. L.; Shi, X. Q.; Zeng, Z.

    2014-08-01

    The electronic transport properties of molecular bridges constructed by C60 and B80 molecules which have the same symmetry are investigated by first principles calculations combined with a non-equilibrium Green's function technique. It is found that, like C60, monomer B80 is a good conductor arising from the charge transfer from the leads to the molecule, while the dimer (B80)2 and (C60)2 are both insulators due to the potential barrier formed at the molecule-molecule interface. Our further study shows that, although both the homogeneous dimer (B80)2 and (C60)2 display poor conductivity, the heterogeneous dimer B80C60 shows a very high conductance as a result from the decreased HOMO-LUMO gap and the excess charge redistribution. Finally, we find that the conductivity of both (B80)2 and (C60)2 can be significantly improved by electron doping, for example, by doping C in (B80)2 and doping N in (C60)2.

  8. 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.

  9. 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.

  10. 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

  11. Modeling the interaction of nanoparticles with mineral surfaces: adsorbed C60 on pyrophyllite.

    PubMed

    Zhu, Runliang; Molinari, Marco; Shapley, Thomas V; Parker, Stephen C

    2013-08-01

    We have applied DFT and molecular modeling to investigate the interaction between carbon-based nanoparticles (CNPs) and geosorbents using the adsorption of buckminsterfullerene (C60) on pyrophyllite and comparing it to the aggregation of C60 molecules. The approach is transferable and can be readily applied to more complex CNP-clay systems. We predict that C60 molecules adsorb preferably on the mineral surface and that the most stable adsorption site is the ditrigonal cavity of the surface. The free energy of adsorption on pyrophyllite was calculated to be more favorable than aggregation both in a vacuum (-0.47 vs -0.41 eV) and in water (-0.25 vs -0.19 eV). In aqueous environments, there are energy barriers as the C60 molecule approaches either a surface or another C60 molecule, and these occur upon disruption of the hydration layers that surround each component. There are also free energy minima that correspond to outer-sphere and more favorable inner-sphere complexes. We expect this adsorptive behavior to be a general feature of CNP-clay systems, and as clays are ubiquitous in the environment, it will offer an inexpensive remediative method to prevent the widespread impact of molecular C60 and CNPs. PMID:23815310

  12. 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.

  13. Water Soluble C60-Liposome and the Biological Effect of C60 to Human Cervix Cancer Cells

    NASA Astrophysics Data System (ADS)

    Li, Wenzhu; Wenzhou, Li; Qian, Kaixian; Huang, Wendong; Zhang, Xinxin; Chen, Wanxi

    1994-04-01

    A preparative technique to obtain water soluble C60-liposome by means of molecular package of C60 with lecithin has been established. The concentration of C60 presented in liposome is 1.09 × 10-4 mol/dm3. The molecular system of C60-liposome with human cervix cancer cells is irradiated with laser (570 nm, 800 mW), there is obvious biological effect of C60 to huma cervix cancer cells.

  14. 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.

  15. Tuning the conductance of H2O@C60 by position of the encapsulated H2O

    PubMed Central

    Zhu, Chengbo; Wang, Xiaolin

    2015-01-01

    The change of conductance of single-molecule junction in response to various external stimuli is the fundamental mechanism for the single-molecule electronic devices with multiple functionalities. We propose the concept that the conductance of molecular systems can be tuned from inside. The conductance is varied in C60 with encapsulated H2O, H2O@C60. The transport properties of the H2O@C60-based nanostructure sandwiched between electrodes are studied using first-principles calculations combined with the non-equilibrium Green’s function formalism. Our results show that the conductance of the H2O@C60 is sensitive to the position of the H2O and its dipole direction inside the cage with changes in conductance up to 20%. Our study paves a way for the H2O@C60 molecule to be a new platform for novel molecule-based electronics and sensors. PMID:26643873

  16. Thermal Transport in C60 Molecular Crystals Above Room Temperature

    NASA Astrophysics Data System (ADS)

    Gorham, Caroline S.; McGaughey, Alan J. H.

    2015-03-01

    The thermal conductivity of solid fullerene molecular systems has garnered significant interest as an example of materials whose thermal transport is dominated by Einstein-type oscillators. Using classical molecular dynamics simulations, this study isolates the roles of intramolecular and intermolecular vibrational degrees of freedom on the bulk thermal conductivity of the face-centered cubic C60 molecular crystal. The Green-Kubo method is used to predict the bulk thermal conductivity. The contributions to thermal transport resulting from collective motions of the molecules, molecular rotations, and intramolecular vibrations are isolated using non-equilibrium methods. These contributions are interpreted using a Debye model, a nearest-neighbor resistance network, and Allen-Feldman theory. C.S.G. is grateful for funding from the NASA Office of Graduate Research through the Space Technology Research Fellowship.

  17. 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.

  18. 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 ...

  19. 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...

  20. 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...

  1. 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

  2. Molecular dynamics simulations on the interactions of low molecular weight natural organic acids with C60.

    PubMed

    Sun, Qian; Xie, Hong-Bin; Chen, Jingwen; Li, Xuehua; Wang, Zhuang; Sheng, Lianxi

    2013-07-01

    As an important part of dissolved organic matter (DOM), low molecular weight organic acids (LOAs) may play a key role in the process for DOM stabilizing carbon nanomaterials (e.g. C60) suspensions in aquatic environment. In addition, both LOAs and C60 have been detected in the troposphere and therefore have a chance to interact with each other in the gaseous phase. However, the mechanism for LOAs-C60 interactions and their environmental implications need further investigations. In this study, molecular dynamics (MD) simulation was employed to investigate the interactions between both neutral and ionic LOAs with C60 in vacuum and water. The results showed that the adsorptions of all LOAs on C60 in energy are favorable, and the aromatic acids have stronger interactions with C60 than the aliphatic acids in vacuum and water. The interaction energies (Eint) of the LOA anions with C60 were weaker than those of their corresponding neutral LOA molecules. The models were also developed to predict and interpret Eint based on the results from MD simulations. Dispersion, induction and hydrophobic interactions were found to be the dominating factor in Eint. These findings indicate that cost-efficient MD simulation can be employed as an important tool to predict the adsorption behavior of LOAs on carbon nanomaterials.

  3. Between Crystal and Glass: Thermal Transport in C60 Molecular Crystals

    NASA Astrophysics Data System (ADS)

    Lu, Simon; Kumar, Sushant; McGaughey, Alan

    Molecular crystals of the fullerene C60 and its derivatives [e.g., phenyl-C61-butyric acid methyl ester (PCBM)] are candidate materials for use in photovoltaics and thermoelectrics. In thermoelectrics, their usefulness is due in part to their exceptionally low thermal conductivities (0.4 W/m-K for C60 and 0.05 W/m-K for PCBM) at room temperature. Little is known regarding the microscopic physics underlying these low thermal conductivities. An important question is whether thermal transport in the C60 molecular crystal is (i) crystal-like, where energy is transported as collective vibrations of the centers of mass of the molecules, or (ii) amorphous-like, where energy diffuses from molecule to molecule. We use molecular dynamics (MD) simulations and the Green-Kubo method to probe this question by predicting the relative contributions of crystal-like and amorphous-like transport to the thermal conductivity of the C60 molecular crystal. To isolate crystal-like transport, we perform simulations on C60 crystals where molecular rotations and intra-molecular vibrations are prohibited. To isolate amorphous-like transport, we fix the centers of mass of the molecules. We compare the MD results to predictions from a fully diffusive network resistance model. This work is supported by the National Science Foundation (Grant DMR-1507325).

  4. Theoretical characterisation of irreversible and reversible hydrogen storage reactions on Ni-doped C60 fullerene

    NASA Astrophysics Data System (ADS)

    Shalabi, A. S.; El Mahdy, A. M.; Soliman, K. A.; Taha, H. O.

    2014-12-01

    An attempt has been made to characterise the irreversible and reversible hydrogen storage reactions on Ni-doped C60 fullerene by using the state of the art density functional theory calculations. The single Ni atom prefers to bind at the bridge site between two hexagonal rings of C60 fullerene, and can bind up to four hydrogen molecules with average adsorption energies of -0.85, -0.83, -0.58, and -0.31 eV per hydrogen molecule. No evidence for metal clustering in the ideal circumstances and the hydrogen storage capacity is expected to be as large as 8.9 wt%. While the desorption activation barriers of the complexes nH2NiC60 (n = 1, 2) are outside the desirable energy window recommended by the department of energy for practical applications (-0.2 to -0.6 eV), the desorption activation barriers of the complexes nH2NiC60 (n = 3, 4) are inside this window. The irreversible 2H2 + NiC60 and reversible 3H2 + NiC60 interactions are characterised in terms of several theoretical parameters such as: (1) densities of states and projected densities of states, (2) pairwise and non-pairwise additivity, (3) infrared, Raman, and proton magnetic resonance spectra, (4) electrophilicity, and (5) statistical thermodynamic stability.

  5. 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

  6. 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.

  7. 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.

  8. 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...

  9. 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.

  10. Electron Impact Excitation of C60 Adducts: Flourescence From C60OH and C60H Species

    NASA Technical Reports Server (NTRS)

    Trajmar, S.; Kanik, I.

    1996-01-01

    An investigation concerning possible visible and UV photon emissions by gas phase C(sub 60) ( and C(sub 70)) samples under electron impact excitation was caried out in the 180-750 nm spectral region. Radiation resembling OH (A (sup 2)pi {leads to}X (sup 2){summation}) emission bands and H Balmer series was observed. Based on our investigations, it is concluded that none of the observed emission was associated with the fullerene molecule itself but with the C(sub 60)OH and C(sub 60)H adducts (which are present in the fullerene samples). We also conclude that in these adducts, simultaneous ionization and excitation take place under electron impact and the excited ionic species (C(sub 60)+OH* and C(sub 60)+H*) decay by radiation which was observed in our experiments. These surprising results reveal an interesting new character of buckyball adducts.

  11. Role of electron energy loss in modification of C60 thin films by swift heavy ions

    NASA Astrophysics Data System (ADS)

    Bajwa, Navdeep; Ingale, Alka; Avasthi, D. K.; Kumar, Ravi; Tripathi, A.; Dharamvir, Keya; Jindal, V. K.

    2008-09-01

    This paper presents a comparative study of the effects of irradiation by swift heavy ions (SHIs) with Se values ranging from 80 to 1270 eV/Å and fluence ranges varying between 1010 and 1014 ions/cm2 incident on thin films of C60. The control over Se is exercised through the choice of ion species for irradiation (O, Ni, and Au). Structural changes in C60 were investigated quantitatively using Raman spectroscopy. The results indicate that at low fluences polymer formation takes place whereas at high fluences there is complete fragmentation of C60, resulting in amorphous carbon formation. Measured values of band gap and in situ resistivity decrease with fluence. This result is consistent with the structural modifications observed by Raman spectroscopy. The composition of the polymer fraction formed (e.g., the content of two dimensional polymerized network of C60 molecules) as well as that of a-C (e.g., the content of nanographite) also vary with Se of the ion used. A phenomenological model, taking into account the ion track, enables us to explain the trend of polymer formation as well as fragmentation of C60, with increasing fluence of SHI. The cross section for damage (fragmentation of C60 molecules) has two values—one effective at low fluences and the other at high fluences. By arriving at a quantitative formula giving the fraction of polymer/damaged C60 molecules at any given fluence, we are able to predict the fluence and ion species required for a given amount of polymerization/damage or vice versa. Effort has been made to correlate Se and Sn values to the damage cross sections using data from this work along with those from other experiments using keV and MeV ions.

  12. Metal-oxide-semiconductor diodes containing C60 fullerenes for non-volatile memory applications

    NASA Astrophysics Data System (ADS)

    Beckmeier, Daniel; Baumgärtner, Hermann

    2013-01-01

    For non-volatile memories, silicon-oxide-nitride-oxide-silicon or floating gate structures are used to store information by charging and discharging electronic states reversibly. In this article, we propose to replace the floating gate by C60 molecules. This would allow more defined programming voltages because of the discrete molecular energy levels and a higher resistance to tunneling oxide defects because of the weak electrical connection between the single molecules. Such C60 MOS diode structures are produced and their electrical properties are analyzed regarding current transport and charging mechanism of the molecules. To create the MOS structures, C60 molecules (5% of a monolayer) are evaporated onto a part of a clean silicon wafer and covered by amorphous silicon in situ in an ultra high vacuum system. Then the wafer is oxidized in wet atmosphere at just 710 °C through the C60 layer. The goal is to produce a clean oxide above and under the molecules without destroying them. Aluminum gate contacts are defined on top of these layers to perform complementary capacitance voltage (CV) and current voltage (IV) measurements. First, the gate voltage is swept to analyze the injection current, then CV measurements are performed after each sweep to analyze the charge state of the C60 layer and the oxide quality. Reference diodes without C60 on the same wafer show an identical Fowler-Nordheim (FN) tunneling behavior for currents injected from silicon or from aluminum, respectively. In the CV curves, no pronounced flatband voltage shift is observable. In diodes with C60, for negative gate voltages, a classical FN tunneling is observed and compared to theory. The electron injection from silicon shows a different tunneling current behavior. It starts at a lower electric field and has a smaller slope then a FN current would have. It is identified as a trap-assisted tunneling (TAT) current caused by oxidation-induced traps under the C60 layer. It is modeled by an

  13. Electronic Pair-Binding and Hund's Rule Violations in Doped C60

    NASA Astrophysics Data System (ADS)

    Jiang, Hong-Chen; Kivelson, Steven

    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 electron 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. HCJ and SAK were supported by the Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract DE-AC02-76SF00515.

  14. Effect of Water Hydrogen Bonding on the Solvent-Mediated "Oscillatory" Repulsion of C60 Fullerenes in Water.

    PubMed

    Djikaev, Yuri S; Ruckenstein, Eli

    2015-05-01

    The solvent-mediated interaction of C60 fullerenes in liquid water is examined by using the combination of the probabilistic hydrogen bond model with the density functional theory. This combination allows one to take into account the effect of hydrogen bonding between water molecules on their interaction with fullerenes and to construct an approximation for the distribution of water molecules in the system, which provides an efficient foundation for studying hydrophobic phenomena. Our numerical evaluations predict the solvent-induced interaction of two C60 fullerenes in water at 293 K to have an oscillatory-repulsive character (previously observed in molecular dynamics simulations) only when the vicinal water-water hydrogen bonds are slightly weaker than bulk ones. Besides indicating the direction of the energetic alteration of water-water hydrogen bonds near C60 fullerenes, our model also suggests that the hydrogen bonding ability of water plays a defining role in the solvent-mediated C60-C60 repulsion.

  15. 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

  16. Electrochemical studies of C60 grafted nonconjugated polymer

    NASA Astrophysics Data System (ADS)

    Jose, Renu

    2013-06-01

    Organic semiconductors like C60 have a range of interesting properties, and they exhibit potential applications in the field of organic electronics. The C60 grafted nonconjugated polymer is prepared by chemical method and the polymer used for this purpose is polybutadiene(PB). The formation of the PB-C60 is analysed by UV-visible spectroscopy. The cyclic voltametry and impedance spectroscopic studies of C60 grafted polybutadiene were done by electrochemical work station. The electrochemical properties are carried out using three electrode systems with platinum as reference. The results show there is considerable change in the electronaffinity of polybutadiene.

  17. 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.

  18. The effect of magnesium added at C60/Rubrene heterointerfaces

    NASA Astrophysics Data System (ADS)

    Cheng, Chiu-Ping; Lee, Cheng-Wei; Chu, Yu-Ya; Wei, Ching-Hsuan; Pi, Tun-Wen

    2013-12-01

    This study examines the effect of adding magnesium (Mg) at C60/rubrene heterointerfaces by using synchrotron-radiation photoemission spectroscopy. The heterointerface was obtained by depositing C60 on a 4-Å Mg/rubrene surface. The photoemission spectra showed that the added Mg preferentially interacts with and transfers negative charges to C60. The interfacial dipole potential was significantly enlarged, as was the separation between the lowest unoccupied molecular orbital of C60 and the highest occupied molecular orbital of rubrene. The results demonstrate that the addition of Mg should be an effective method for improving the efficiency of light- and current-generating devices.

  19. When a nanoparticle meets a superhalogen: a case study with C60 fullerene.

    PubMed

    Sikorska, Celina

    2016-07-28

    The ability of a selected nanoparticle to form stable systems with superhalogens (i.e. AlF4, AlCl4, MgF3, MgCl3, LiF2, LiCl2, and LiI2) is examined on the basis of theoretical considerations supported by ab initio calculations. It is demonstrated that the C60 fullerene molecule should form stable and strongly bound (C60)˙(+)(superhalogen)(-) radical cation salts when combined with an appropriately chosen superhalogen radical (acting as an oxidizing agent). The conclusion is supported by providing: (i) the structural deformation of superhalogens and C60 nanoparticles upon ionization, (ii) predicted charge flow between the fullerene and each superhalogen (which allows estimating the amount of electron density withdrawn from the C60 molecule during the ionization process), (iii) the localization of the spin density distribution, and (iv) the interaction energies for the compounds obtained both at the B3LYP/6-31+G(d) level and at the B3LYP-D3/6-31+G(d) level. Solvent effects have been considered in the present study by means of the polarizable continuum model. It is found that the stability of C60/superhalogen species can be improved in solvents. We believe that the results provided in this contribution may likely be of prospective relevance in the future studies on the issue of binding and removal of this potentially risky nanoparticle. PMID:27346461

  20. Laboratory confirmation of C60(+) as the carrier of two diffuse interstellar bands.

    PubMed

    Campbell, E K; Holz, M; Gerlich, D; Maier, J P

    2015-07-16

    The diffuse interstellar bands are absorption lines seen towards reddened stars. None of the molecules responsible for these bands have been conclusively identified. Two bands at 9,632 ångströms and 9,577 ångströms were reported in 1994, and were suggested to arise from C60(+) molecules (ref. 3), on the basis of the proximity of these wavelengths to the absorption bands of C60(+) measured in a neon matrix. Confirmation of this assignment requires the gas-phase spectrum of C60(+). Here we report laboratory spectroscopy of C60(+) in the gas phase, cooled to 5.8 kelvin. The absorption spectrum has maxima at 9,632.7 ± 0.1 ångströms and 9,577.5 ± 0.1 ångströms, and the full widths at half-maximum of these bands are 2.2 ± 0.2 ångströms and 2.5 ± 0.2 ångströms, respectively. We conclude that we have positively identified the diffuse interstellar bands at 9,632 ångströms and 9,577 ångströms as arising from C60(+) in the interstellar medium. PMID:26178962

  1. Inclusion properties of 3-fluoromesotetraphenylporphyrin with C 60 and C 70

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sumanta; Nayak, Sandip K.; Chattopadhyay, Subrata; Ghosh, Kalyan; Banerjee, Manas

    2007-08-01

    To improve the selectivity ratio of C 70 over C 60, a new designer molecule, viz., 3-fluoromesotetraphenylporphyrin ( 1) has been reported in the present investigations. Fluoresence studies reveal that the Q-absorption band of 1 gets sufficient quenching effect upon addition of both C 60 and C 70. Binding constants ( K) of the C 60/ 1 and C 70/ 1 complexes are estimated to be 580 and 10,800 dm 3 mol -1, respectively. Thus, K/K is ˜19 which is very large and even comparable with other macrocyclic host molecules like calix[5]arene, azacalix[ m]arene[ n]pyridine, cyclotriveratrylenophane and calixarene bisporphyrin. 1H NMR chemical shift measurements show that the -NH- proton of 1 suffers more shifts in presence of C 70 compared to C 60. This finding also offers a good support in favor of high K value for C 70/ 1 complex as well as large selectivity ratio of C 70 over C 60.

  2. Computer simulations of the Adsorption of Xenon onto a C60 monolayer on Ag (111)

    NASA Astrophysics Data System (ADS)

    Gatica, Silvina; Cole, Milton; Diehl, Renee

    2007-03-01

    We performed Grand Canonical Monte Carlo simulations to study the adsorption of Xenon on a substrate composed of C60 molecules placed on top of a Ag(111) surface. The C60 molecules form a commensurate structure at a distance of 0.227 nm above the Ag surface. The interaction potential between the Xe atoms and the substrate has two contributions: from the C60 molecules and from the Ag atoms. In the simulations, the interaction with the Ag surface was computed using an ab initio van der Waals potential, varying as 1/d^3. The interaction between the Xe atoms and each C60 molecule was computed using a potential previously developed by Hernandez et.al. (E. S. Hernandez, M. W. Cole and M. Boninsegni, ``Wetting of spherical surfaces by quantum fluids'', J. Low Temp. Phys. 134, 309-314 (2004)), who integrated the Lennard Jones interaction over the surface of a spherical buckyball. The total potential has especially attractive 3-fold sites, positioned 0.4 nm above the point between each three buckyballs. The low coverage uptake populates those sites, and then continues forming a monolayer. The adsorption isotherms show several steps, typical of substrates that have distinct adsorption sites. We compare the results with the experimental data.

  3. Adsorption of C60 buckminster fullerenes on an 11-amino-1-undecene-covered Si(111) substrate.

    PubMed

    Zhang, Xiaochun; Teplyakov, Andrew V

    2008-02-01

    Buckminster fullerene C60 was used as a model to understand the attachment chemistry of large molecules on amine-terminated self-assembled monolayers (SAM) on semiconductor substrates. This type of interface serves as a prototype for future devices in such fields as solar energy conversion, biosensing, catalysis, and molecular electronics. Fullerene C60 was attached to 11-amino-1-undecene self-assembled monolayers on a Si(111) surface. The chemical state and topography of the C60-modified surface were characterized by surface analytical spectroscopic and microscopic methods and by computational investigation. X-ray photoelectron spectroscopy revealed that the secondary amine group is formed between the C60 and the 11-amino-1-undecene SAM on the surface. The appearance of the pi-pi* C 1s shakeup peak confirmed the presence of C60 on the surface. Infrared spectroscopic studies verified several characteristic features of the C60 skeleton vibration and the 11-amino-1-undecene vibrational signature. The atomic force microscopy investigation suggested that the fullerene molecules produce surface features with an apparent height of approximately 2 nm and an average width of approximately 20 nm. A parallel study was performed on a Au(111) surface for comparison with the results obtained on the silicon substrate. The reaction between fullerene molecules and approximately 1% 11-amino-1-undecene diluted in decene SAM on the Si(111) surface accordingly yielded dilute and uniformly distributed C60 molecules on the surface, which indicated that the amine groups were the reactive sites.

  4. Superconductivity of Fullerides with Composition AGax C_{60} and AGax My C_{60} (A = K, Rb; M = In, Sn, Bi)

    NASA Astrophysics Data System (ADS)

    Kulbachinskii, V. A.; Lunin, R. A.; Velikodny, Yu. A.; Bulychev, B. M.

    2016-01-01

    The new heterofullerides with the composition AGax C_{60} and AGax My C_{60} (A = K, Rb; M = In, Sn, Bi; x,y<1 ) have been synthesized by a new method using liquid alloys of alkali metal with gallium or gallams. The temperature dependence of the magnetic susceptibility was measured in the temperature range from 4.2 to 100 K, and transitions to a superconducting state were observed at temperatures Tc ranging from 7 to 17.5 K. The superconductivity was found for fullerides RbGax C_{60} and RbGax Iny C_{60} with orthorhombic lattice.

  5. Analyses of the Binding between Water Soluble C60 Derivatives and Potential Drug Targets through a Molecular Docking Approach

    PubMed Central

    Liu, Junjun; Zhang, Houjin

    2016-01-01

    Fullerene C60, a unique sphere-shaped molecule consisting of carbon, has been proved to have inhibitory effects on many diseases. However, the applications of C60 in medicine have been severely hindered by its complete insolubility in water and low solubility in almost all organic solvents. In this study, the water-soluble C60 derivatives and the C60 binding protein’s structures were collected from the literature. The selected proteins fall into several groups, including acetylcholinesterase, glutamate racemase, inosine monophosphate dehydrogenase, lumazine synthase, human estrogen receptor alpha, dihydrofolate reductase and N-myristoyltransferase. The C60 derivatives were docked into the binding sites in the proteins. The binding affinities of the C60 derivatives were calculated. The bindings between proteins and their known inhibitors or native ligands were also characterized in the same way. The results show that C60 derivatives form good interactions with the binding sites of different protein targets. In many cases, the binding affinities of C60 derivatives are better than those of known inhibitors and native ligands. This study demonstrates the interaction patterns of C60 derivatives and their binding partners, which will have good impact on the fullerene-based drug discovery. PMID:26829126

  6. Growth and Potential Damage of Human Bone-Derived Cells Cultured on Fresh and Aged C60/Ti Films

    PubMed Central

    Kopova, Ivana; Lavrentiev, Vasily; Vacik, Jiri; Bacakova, Lucie

    2015-01-01

    Thin films of binary C60/Ti composites, with various concentrations of Ti ranging from ~ 25% to ~ 70%, were deposited on microscopic glass coverslips and were tested for their potential use in bone tissue engineering as substrates for the adhesion and growth of bone cells. The novelty of this approach lies in the combination of Ti atoms (i.e., widely used biocompatible material for the construction of stomatological and orthopedic implants) with atoms of fullerene C60, which can act as very efficient radical scavengers. However, fullerenes and their derivatives are able to generate harmful reactive oxygen species and to have cytotoxic effects. In order to stabilize C60 molecules and to prevent their possible cytotoxic effects, deposition in the compact form of Ti/C60 composites (with various Ti concentrations) was chosen. The reactivity of C60/Ti composites may change in time due to the physicochemical changes of molecules in an air atmosphere. In this study, we therefore tested the dependence between the age of C60/Ti films (from one week to one year) and the adhesion, morphology, proliferation, viability, metabolic activity and potential DNA damage to human osteosarcoma cells (lines MG-63 and U-2 OS). After 7 days of cultivation, we did not observe any negative influence of fresh or aged C60/Ti layers on cell behavior, including the DNA damage response. The presence of Ti atoms resulted in improved properties of the C60 layers, which became more suitable for cell cultivation. PMID:25875338

  7. Effect of K Doping on Rubrene: C60 Heterojunctions

    NASA Astrophysics Data System (ADS)

    Cheng, Chiu-Ping; Chu, Yu-Ya; Lu, Meng-Han; Pi, Tun-Wen

    Using synchrotron-radiation photoemission spectroscopy, we have studied the effect of potassium doping on rubrene: C60 heterojunctions. The potassium-doped heterointerfaces was obtained by means of C60 on a K0.5Rubrene surface. As the heterointerface formed, the potassium diffuses into the C60 layer, and transfers negative charge into the lowest unoccupied molecular orbital (LUMO) of C60. With K doping, the enhancement of the interfacial dipole potential, and the creation of gap states, as well as the increase in the separation between the LUMO of C60 and the highest occupied molecular orbital (HOMO) of rubrene could possibly improve the organic light- and current-generating dual devices.

  8. DFT based modeling of C60/Dichloropentacene/Au OPV heterojunctions

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Tang, Jian-Ming; Pohl, Karsten

    2012-02-01

    The co-assembly of functionalized pentacenes (electron-donor materials) and fullerenes (electron-acceptor materials) on metal substrates provides a model for studying the structural and electronic properties for novel organic photovoltaic (OPV) heterojunctions. Our previous STM experimental results show C60 to form single, double and triple nano chains on an intact single-domain, brick-wall structured 6,13-dichloropentacene (DCP) monolayer adsorbed on stepped Au(788). Here, we present theoretical DFT calculations of the geometric and electronic structure, and the charge transfer in this interacting three-component system. Our calculations show that single C60 molecules prefer to either absorb on top of the DCP molecules (slightly shifted off the Cl center) or in between the DCP rows of the brick-wall structure. When adsorbing chains of C60 they will align with either the troughs in between the DCP rows or the top of the DCP rows, in agreement with experiment. Compared to the isolated DCP molecules, the HOMO and LUMO levels move up towards the vacuum level by about 1 eV upon monolayer formation, resulting in charge transfer to C60.

  9. Carbon fullerenes (C60s) can induce inflammatory responses in the lung of mice.

    PubMed

    Park, Eun-Jung; Kim, Hero; Kim, Younghun; Yi, Jongheop; Choi, Kyunghee; Park, Kwangsik

    2010-04-15

    Fullerenes (C60s) occur in the environment due to natural and anthropogenic sources such as volcanic eruptions, forest fires, and the combustion of carbon-based materials. Recently, production and application of engineered C60s have also rapidly increased in diverse industrial fields and biomedicine due to C60' unique physico-chemical properties, so toxicity assessment on environmental and human health is being evaluated as a valuable work. However, data related to the toxicity of C60s have not been abundant up to now. In this study, we studied the immunotoxic mechanism and change of gene expression caused by the instillation of C60s. As a result, C60s induced an increase in sub G1 and G1 arrest in BAL cells, an increase in pro-inflammatory cytokines such as IL-1, TNF-alpha, and IL-6, and an increase of Th1 cytokines such as IL-12 and IFN-r in BAL fluid. In addition, IgE reached the maximum at 1 day after treatment in both BAL fluid and the blood, and decreased in a time-dependent manner. Gene expression of the MHC class II (H2-Eb1) molecule was stronger than that of the MHC class I (H2-T23), and an increase in T cell distribution was also observed during the experiment period. Furthermore, cell infiltration and expression of tissue damage related genes in lung tissue were constantly observed during the experiment period. Based on this, C60s may induce inflammatory responses in the lung of mice.

  10. Carbon fullerenes (C60s) can induce inflammatory responses in the lung of mice

    SciTech Connect

    Park, Eun-Jung; Kim, Hero; Kim, Younghun; Yi, Jongheop; Choi, Kyunghee; Park, Kwangsik

    2010-04-15

    Fullerenes (C60s) occur in the environment due to natural and anthropogenic sources such as volcanic eruptions, forest fires, and the combustion of carbon-based materials. Recently, production and application of engineered C60s have also rapidly increased in diverse industrial fields and biomedicine due to C60' unique physico-chemical properties, so toxicity assessment on environmental and human health is being evaluated as a valuable work. However, data related to the toxicity of C60s have not been abundant up to now. In this study, we studied the immunotoxic mechanism and change of gene expression caused by the instillation of C60s. As a result, C60s induced an increase in sub G1 and G1 arrest in BAL cells, an increase in pro-inflammatory cytokines such as IL-1, TNF-alpha, and IL-6, and an increase of Th1 cytokines such as IL-12 and IFN-r in BAL fluid. In addition, IgE reached the maximum at 1 day after treatment in both BAL fluid and the blood, and decreased in a time-dependent manner. Gene expression of the MHC class II (H2-Eb1) molecule was stronger than that of the MHC class I (H2-T23), and an increase in T cell distribution was also observed during the experiment period. Furthermore, cell infiltration and expression of tissue damage related genes in lung tissue were constantly observed during the experiment period. Based on this, C60s may induce inflammatory responses in the lung of mice.

  11. DFT based modeling of C60/Dichloropentacene on stepped Au surfaces

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Tang, Jian-Ming; Pohl, Karsten

    2013-03-01

    The co-assembly of functionalized pentacenes (electron-donor materials) and fullerenes (electron-acceptor materials) on metal substrates provides a model for studying the structural and electronic properties for novel organic photovoltaic (OPV) heterojunctions. Our previous STM experimental results show C60 to form molecular chains on an intact single-domain, brick-wall structured 6,13-dichloropentacene (DCP) monolayer adsorbed on stepped Au(788). Here, we have included a stepped gold substrate in DFT calculations for the geometric and electronic structure of this interacting three-component system. Our calculations show that C60 molecular chain prefer to absorb on top of the DCP molecules on the upper step edge. We calculate the dipole moments for various C60 configurations. The stepped gold substrate interaction shows a major influence on this unique molecular chain formation.

  12. Disclinations in C60 molecular layers on WO2/W (110 ) surfaces

    NASA Astrophysics Data System (ADS)

    Bozhko, S. I.; Taupin, V.; Lebyodkin, M.; Fressengeas, C.; Levchenko, E. A.; Radikan, K.; Lübben, O.; Semenov, V. N.; Shvets, I. V.

    2014-12-01

    A scanning tunneling microscopy study of a planar close-packed C60 hexagonal molecular layer on a WO2/W (110 ) substrate reveals the existence of C60 domains exhibiting two preferred orientations at an angle with an underlying periodic groove structure in the substrate. An analysis of the van der Waals interactions between substrate and layer retrieves the observed misorientations as those corresponding to minima in the interaction energy of the substrate-layer system. The misorientation between two C60 domains is accommodated in a tilt boundary by a linear array of molecular structural units identified as disclination dipoles, i.e., rotational defects in the hexagonal structure of the layer. A field theory of disclinations and dislocations is used to construct maps of the elastic energy, strains, curvatures, and stresses induced by the lattice defects over the layer. The predicted regions of high compression are found to overlap with those where the fullerene molecules do not undergo rotation.

  13. Cycloparaphenylene-based ionic donor-acceptor supramolecule: isolation and characterization of Li⁺@C60⊂[10]CPP.

    PubMed

    Ueno, Hiroshi; Nishihara, Taishi; Segawa, Yasutomo; Itami, Kenichiro

    2015-03-16

    The first cycloparaphenylene (CPP)-based ionic donor-acceptor supramolecule Li(+)@C60⊂[10]CPP⋅X(-) has been synthesized. X-ray crystallography not only confirmed the molecular structure of Li(+)@C60⊂[10]CPP⋅X(-) but also uncovered the formation of a unique ionic crystal. The strong charge-transfer interaction between [10]CPP and Li(+)@C60, which was confirmed by electrochemical measurement and spectroscopic analyses, caused significant delocalization of the positive charge across the entire complex. PMID:25693784

  14. Core-shell nanopillars of fullerene C60/C70 loading with colloidal Au nanoparticles: a Raman scattering investigation.

    PubMed

    Luo, Zhixun; Zhao, Yong Sheng; Yang, Wensheng; Peng, Aidong; Ma, Ying; Fu, Hongbing; Yao, Jiannian

    2009-09-01

    High-density ordered core-sheath nanopillars of fullerene C60/C70 loading with colloidal Au nanoparticles were fabricated with a template method. The anodic aluminum oxide (AAO) template was first imbedded with the fullerene C60/C70 molecules and then followed by a pressure-difference approach for Au colloid. High-quality surface-enhanced Raman scattering (SERS) spectra of fullerene C60/C70 were obtained. The spectra show intense SERS signals with a fluorescence-free background, even with a 514 nm excitation at which the normal Raman of fullerene C60/C70 present poor signal-to-noise. The assembly of the fullerene C60/C70 on the inner walls of the AAO pores along the Au nanopillars lead to fluorescence quenching; meanwhile, the high-density and ordered arrays of Au nanopillars contribute to surface plasmon resonance for the SERS effect. PMID:19653673

  15. 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.

  16. Computational study of enantioselective interaction between C60 fullerene and its derivatives with L-histidine.

    PubMed

    Lal, Bhajan

    2007-04-01

    The mechanism of the enantioselective binding of L-histidine with C(60) fullerene and its derivatives, (1,2-methanofullerene C(60))-61-carboxylic acid, diethyl (1,2-methanofullerene C(60))-61-61-dicarboxylate and tert-butyl (1,2-methanofullerene C(60))-61-carboxylate based chiral selectors was studied by quantum chemical calculations. All the molecules were fully optimized at RHF/6-31G* basis set. Relative energies between the different complexes were subsequently estimated with single-point electronic energies computed using Møller-Plesset perturbation theory (MP2). Stability and feasibility of all the generated structures were supported by their respective energy minima and fundamental frequencies. It was observed that interaction of fullerene derivatives with L-histidine is due to the existence of hydrogen bonding forces during the complex formation. The intermolecular forces, flow of atomic charges, binding energy, hardness, dipole moment and localization of electrostatic potential are in agreement with enantioselective interaction of L-histidine with C(60) fullerene and its derivatives. It is found that theoretical evaluation to be consistent with the experimental data.

  17. Addition reaction of alkyl radical to C60 fullerene: Density functional theory study

    NASA Astrophysics Data System (ADS)

    Tachikawa, Hiroto; Kawabata, Hiroshi

    2016-02-01

    Functionalized fullerenes are known as a high-performance molecules. In this study, the alkyl-functionalized fullerenes (denoted by R-C60) have been investigated by means of the density functional theory (DFT) method to elucidate the effects of functionalization on the electronic states of fullerene. Also, the reaction mechanism of alkyl radicals with C60 was investigated. The methyl, ethyl, propyl, and butyl radicals (denoted by n = 1-4, where n means the number of carbon atoms in the alkyl radical) were examined as alkyl radicals. The DFT calculation showed that the alkyl radical binds to the carbon atom of C60 at the on-top site, and a strong C-C single bond is formed. The binding energies of alkyl radicals to C60 were distributed in the range of 31.8-35.1 kcal mol-1 at the CAM-B3LYP/6-311G(d,p) level. It was found that the activation barrier exists before alkyl addition, the barrier heights were calculated to be 2.1-2.8 kcal mol-1. The electronic states of R-C60 complexes were discussed on the basis of the theoretical results.

  18. The endohedral model of muonium in solid C 60

    NASA Astrophysics Data System (ADS)

    Donzelli, O.; Briere, Tina; Das, T. P.

    1994-06-01

    The ab-initio Unrestricted Hartree-Fock procedure is used to investigate the stability of the muonium internally bound to a C 60 fulleren. Within an accuracy of less than 0.1 eV we find equilibrium energy of the endohedral center almost degenerate with the Mu @C 60 energy and good agreement with the experimental hyperfine coupling constants. These results, together with the difficulties connected with the dynamics of C 60 in the exohedral model, which do not arise in the endohedral model, suggest that it should be considered in order to explain the observed μSR data.

  19. 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.

  20. 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...

  1. 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)

  2. 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.

  3. Density functional investigation of CO and NO adsorption on TM-decorated C60 fullerene

    NASA Astrophysics Data System (ADS)

    El Mahdy, A. M.

    2016-10-01

    We have analysed the adsorptions of CO and NO molecules on pristine, TM (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) in TM-doped fullerene C60 by using density functional theory (DFT) calculations at B3LYP/6-31g(d) theoretical level. This work revealed that the transition metal doped fullerenes were more highly sensitive to CO and NO adsorption than that of pure fullerene C60. The Fe-doped fullerenes C60 displayed the strongest interaction with C and N atoms of CO and NO molecules respectively. The nature of charge transfer between the d-orbitals of TM, and the π* orbital of the nearby C and N of CO and NO are clarified. Natural bond orbital (NBO) analysis reveals that the electronic configuration of the doped TM metal represents a qualitative change with respect to that of the free-metal. The binding of CO and NO precursor is mostly dominated by the metal E (i) (XO ..TM) pairwise additive contributions, and the role of the C60 is not restricted to supporting the metal.

  4. Molecular simulation of C 60 adsorption onto a TiO 2 rutile (1 1 0) surface

    NASA Astrophysics Data System (ADS)

    Carvalho, A. J. Palace; Ramalho, J. P. Prates

    2010-06-01

    A Monte Carlo molecular simulation study is presented on the adsorption and growth of C 60 films on the surface of the (1 1 0) face of rutile. Simulations are performed for a temperature of 600 K using atomistic models both for the fullerene molecules and the TiO 2 surface. It is found in this work that C 60 is adsorbed preferably in an ordered arrangement along the surface depressions over the exposed undercoordinated Ti cations. At low densities adsorption occurs preferably at alternate rows, with locations in consecutive rows being occupied appreciably only at higher C 60 densities. At low densities, the fullerene molecules tend to aggregate into islands in the surface plane. Additional layers of C 60 form only as the density increases, and do so before a monolayer is completed in all consecutive rows. Full monolayer capacity obtained at the highest densities is about 0.9 C 60 molecules per nm 2, but this is only achieved by completing the packing of molecules in interstices at a slightly upper level. The fraction of the molecules that lie closest to the surface only amounts to 0.6 molecules per nm 2.

  5. Dependence of the band structure of C-60 monolayers on molecularorientations and doping observed by angle resolved photoemission

    SciTech Connect

    Brouet, V.; Yang, W.L.; Zhou, X.J.; Hussain, Z.; Shen, Z.X.

    2008-01-17

    We present angle resolved photoemission studies of C60monolayers deposited on Ag surfaces. The electronic structure of thesemonolayers is derived from the partial filling of the narrow, 6-folddegenerated, C60 conduction band. By comparing the band structure in twomonolayers deposited, respectively, on Ag(111) and Ag(100), we show thatthe molecular degree of freedom, in this case the relative orientationsbetween C60 molecules, is essential to describe the band structure. Wefurther show that the evolution of the band as a function of doping doesnot follow a rigid band-filling picture. Phase separation is observedbetween a metallic and an insulating phase, which might be a result ofstrong correlations.

  6. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    Fullerenes (C60 and C70) have recently been identified in a shock-produced breccia (Onaping Formation) associated with the 1.85-Ga Sudbury Impact Crater. The presence of parts-per-million levels of fullerenes in this impact structure raises interesting questions about the processes that led to the formation of fullerenes and the potential for delivery of intact organic material to the Earth by a large bolide (e.g., asteroid or comet). Two possible scenarios for the presence of fullerenes in the Sudbury impact deposits are that (1) fullerenes are synthesized within the impact plume from the C contained in the bolide; or (2) fullerenes are already present in the bolide and survived the impact event. The correlation of C and trapped noble gas atoms in meteorites is well established. Primitive meteorites contain several trapped noble gas components that have anomalous isotopic compositions, some of which may have a presolar origin. Several C-bearing phases, including SiC, graphite, and diamond, have been recognized as carriers of trapped noble gases. It has also been suggested that fullerenes (C60 and C70) might be a carrier of noble gas components in carbonaceous chondrites. Recently, fullerenes have been detected in separate samples in the Allende meteorite. Carbon-60 is large enough to enclose the noble gases He, Ne, Ar, Kr, and Xe, but it is too small to contain diatomic gases such as N2 or triatomic gases such as CO2. Recent experimental work has demonstrated that noble gases of a specific isotopic composition can be introduced into synthetic fullerenes at high temperatures and pressures; these encapsulated gases can then be released by the breaking of one or more C bonds during step-heating under vacuum. These thermal-release patterns for He encapsulated within the C60 molecule (He@C60) are similar to the patterns for acid residues of carbonaceous chondrites, suggesting that fullerenes could be an additional carrier of trapped noble gases in acid residues of

  8. Computer simulation of the infrared spectra of endohedral metallofullerenes Li2C60 and Na2C60

    NASA Astrophysics Data System (ADS)

    Butyrskaya, E. V.; Zapryagaev, S. A.

    2009-03-01

    Using the Gaussian03 computer software, the infrared spectra of endohedral Li2C60 and Na2C60 are calculated by the Hartree-Fock method in the 3-21 G basis set. The calculation is carried out for three cases: (i) metallofullerenes without a solvent, (ii) metallofullerenes in a toluene solution, and (iii) metallofullerenes in a tetrahydrofuran solution. The effect of a solvent on the energetic, electrical, and spectral characteristics of the metallofullerenes is studied.

  9. Quantification of C60 fullerene concentrations in water.

    PubMed

    Chen, Zhuo; Westerhoff, Paul; Herckes, Pierre

    2008-09-01

    The growing usage of nanomaterials is causing emerging concern regarding their environmental behavior in aquatic environments. A major need is the capability to detect and quantify nanomaterials in complex water matrices. Carbon60 fullerene is of special interest because of the widespread application of nanocarbon technology. The present study focuses on how to separate and concentrate fullerenes from water containing salts and organic matter and then quantify their concentrations using liquid chromatography coupled with mass spectrometry (LC/MS). The stable aqueous C60 aggregates (nC60) prepared in the present study were approximately 60 to 70 nm in diameter and had an ultraviolet (UV) extinction coefficient of 0.0263 L/mg-cm at 347 nm, which equated to a UV detection limit of 0.4 mg/L based upon an absorbance of 0.01 cm(-1). Ultraviolet analysis is not applicable to use in waters containing salts or organics (e.g., tap water) because of their interferences and potential to aggregate nC60. The LS/MS analysis detected C60 as single fullerene rather than aggregates. Three techniques were developed to separate and concentrate nC60 from ultrapure and tap water into toluene to facilitate LC/MS determination: Evaporation of sample to dryness; extraction using 20% NaCl into toluene; and solid-phase extraction. The first two methods had limitations for use in complex water matrices, but aqueous nC60 concentration as low as 300 ng/L in water were quantified using solid-phase extraction (SPE) separation method. This is the first publication on the application of extraction methods for nC60 from ultrapure and tap waters and determination of detection limits by LC/MS. PMID:19086313

  10. Supramolecular structures and photoelectronic properties of the inclusion complex of a cyclic free-base porphyrin dimer and C60.

    PubMed

    Nobukuni, Hirofumi; Shimazaki, Yuichi; Uno, Hidemitsu; Naruta, Yoshinori; Ohkubo, Kei; Kojima, Takahiko; Fukuzumi, Shunichi; Seki, Shu; Sakai, Hayato; Hasobe, Taku; Tani, Fumito

    2010-10-11

    A cyclic free-base porphyrin dimer H4-CPD(Py) (CPD = cyclic porphyrin dimer) linked by butadiyne moieties bearing 4-pyridyl groups self-assembles to form a novel porphyrin nanotube in the crystalline state. The cyclic molecules link together through nonclassical C-H⋅⋅⋅N hydrogen bonds and π–π interactions of the pyridyl groups along the crystallographic a axis. H4-CPD(Py) includes a C60 molecule in its cavity in solution. In the crystal structure of the inclusion complex (C60⊂H4-CPD(Py)), the dimer “bites” a C60 molecule by tilting the porphyrin rings with respect to each other, and there are strong π–π interactions between the porphyrin rings and C60. The included C60 molecules form a zigzag chain along the crystallographic b axis through van der Waals contacts with each other. Femtosecond laser flash photolysis of C60⊂H4-CPD(Py) in the solid state with photoexcitation at 420 nm shows the formation of a completely charge-separated state {H4-CPD(Py)·+ + C60·−}, which decays with a lifetime of 470 ps to the ground state. The charge-carrier mobility of the single crystal of C60⊂H4-CPD(Py) was determined by flash photolysis time-resolved microwave conductivity (FP-TRMC) measurements. C60⊂H4-CPD(Py) has an anisotropic charge mobility (Σμ = 0.16 and 0.13 cm2 V(−1)  s(−1)) along the zigzag chain of C60 (which runs at 45° and parallel to the crystallographic b axis). To construct a photoelectrochemical cell, C60⊂H4-CPD(Py) was deposited onto nanostructured SnO2 films on a transparent electrode. The solar cell exhibited photovoltaic activity with an incident photon to current conversion efficiency of 17%.

  11. Nanostructured thin films of C60-aniline dyad clusters: electrodeposition, charge separation, and photoelectrochemistry.

    PubMed

    Kamat, P V; Barazzouk, S; Hotchandani, S; Thomas, K G

    2000-11-01

    Clusters of C60-aniline dyads are deposited as thin films on nanostructured SnO2 electrodes under the influence of an electric field. At low applied DC voltage (<5 V) the clusters in toluene/acetonitrile (1:3) mixed solvent grow in size (from 160 nm to approximately 200 nm in diameter) while at higher voltages (>50 V) they are deposited on the electrode surface as thin films. The C60- aniline dyad cluster films when cast on nanostructured SnO2 films are photoelectrochemically active and generate photocurrent under visible light excitation. These nanostructured fullerene films are capable of delivering relatively large photocurrents (up to approximately 0.2 mA cm(-2), photoconversion efficiency of 3-4%) when employed as photoanodes in photoelectrochemical cells. Both luminescence and transient absorption studies confirm the formation of charge transfer product (C60 anion) following UV/Vis excitation of these films. Photo-induced charge separation in these dyad clusters is followed by the electron injection from C60-anion moiety into the SnO2 nanocrystallites. The oxidized counterpart is reduced by the redox couple present in the electrolyte, thus regenerating the dyad clusters. The feasibility of casting high surface area thin fullerene films on electrode surfaces has opened up new avenues to utilize dyad molecules of sensitizer bridge donor type in light energy conversion devices, such as solar cells.

  12. Modulation of the photophysical properties of C60 by electronic confinement effect.

    PubMed

    Márquez, F; Sabater, M J

    2005-03-01

    This research work reports on the incorporation of fullerene C60 in diverse inorganic and organic matrixes and how these different environments induce changes on the photophysical properties of the molecule depending on the cavity dimensions of the host. Indeed the fluorescence emission band of C60 experiences a progressive bathochromic shift with respect to C60 in solution as the cavity dimensions of the host decrease in going from the mesoporous material MCM41 to UTD-1 and Na-Y zeolites. This experimental observation, which has been documentarily confirmed by theoretical predictions and recent experimental results, is a reflection of the confinement effect imposed by the host. However, the most striking result reported in this work is that the fluorescence range accessible to this occluded species can be extraordinarily extended by confinement inside the neutral cages of a "dendritic box". The ability of the dendritic shell to create a microenvironment, modifying the properties of its functional core, allows the emission bands of C60 incorporated into a dendrimer to be effectively red-shifted with respect to their emission in solution, and, contrarily to other confined spaces of considerable hardness such as zeolites or the high surface material MCM41, the magnitude of this shifting is maximum and can be modulated under appropriate experimental conditions. This phenomenon has an enormous relevance since it can be exploited in future technological applications. PMID:16833477

  13. The Nature of the Noncovalent Interactions between Benzene and C60 Fullerene.

    PubMed

    Li, Ming-Ming; Wang, Yi-Bo; Zhang, Yu; Wang, Weizhou

    2016-07-21

    Noncovalent interactions between aromatic compounds and fullerenes have received considerable attention in various fields of science and technology. Employing benzene (C6H6) and C60 fullerene as model molecules, we theoretically explored in the present study the nature of this kind of noncovalent interaction. Our results clearly show that the π···π stacking configurations of the complex C6H6···C60 are more strongly bound than in the C-H···π analogues, and the C-H···π interactions in the C-H···π configurations of C6H6···C60 are not of the hydrogen bonds. According to symmetry adapted perturbation theory analyses, all of the configurations of C6H6···C60 are dominated by dispersion forces. The percentage of the dispersion components in the overall attractive interactions for the π···π stacking configurations is smaller than the percentage of the dispersion components in the overall attractive interactions for the C-H···π configurations, whereas the percentage of the electrostatic terms in the overall attractive interactions for the π···π stacking configurations is larger than the percentage of the electrostatic terms in the overall attractive interactions for the C-H···π configurations. This is distinctly different from the case of the benzene dimer. PMID:27366821

  14. A search for C60 in carbonaceous chondrites.

    PubMed

    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.

  15. 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.

  16. 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.

  17. 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.

  18. 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).

  19. Nucleation of C60 on ultrathin SiO2

    NASA Astrophysics Data System (ADS)

    Conrad, Brad; Groce, Michelle; Cullen, William; Pimpinelli, Alberto; Williams, Ellen; Einstein, Ted

    2012-02-01

    We utilize scanning tunneling microscopy to characterize the nucleation, growth, and morphology of C60 on ultrathin SiO2 grown at room temperature. C60 thin films are deposited in situ by physical vapor deposition with thicknesses varying from <0.05 to ˜1 ML. Island size and capture zone distributions are examined for a varied flux rate and substrate deposition temperature. The C60 critical nucleus size is observed to change between monomers and dimers non-monotonically from 300 K to 500 K. Results will be discussed in terms of recent capture zone studies and analysis methods. Relation to device fabrication will be discussed. doi:10.1016/j.susc.2011.08.020

  20. 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.

  1. Low-temperature heat capacity of fullerite C60 doped with deuteromethane

    NASA Astrophysics Data System (ADS)

    Bagatskii, M. I.; Sumarokov, V. V.; Dolbin, A. V.; Sundqvist, B.

    2012-01-01

    The heat capacity C of fullerite doped with deuteromethane (CD4)0.4(C60) has been investigated in the temperature interval 1.2-120 K. The contribution ΔCCD4 of the CD4 molecules to the heat capacity C has been isolated. It is shown that at T ≈ 120 K the rotational motion of CD4 molecules in the octahedral voids of the C60 lattice is weakly hindered. When the temperature is lowered to 80 K, the rotational motion of the CD4 molecules changes from weakly hindered rotation to libration. In the range T = 1.2-30 K, ΔCCD4 is described quite accurately by the sum of contributions from the translational and librational vibrations and tunneling rotation of CD4 molecules. The contribution of tunneling rotation to the heat capacity ΔCCD4(T) is dominant below 5 K. The effect of nuclear-spin conversion of the CD4 molecules on the heat capacity has been observed and the characteristic times for nuclear spin conversion between the lowest levels of the A- and T-species of CD4 molecules at T < 5 K have been estimated. A feature observed in ΔCCD4(T) near T = 5.5 K is most likely a manifestation of a first-order phase transition in the orientational glass form of the solution.

  2. Effect on magnetic properties of germanium encapsulated C60 fullerene

    NASA Astrophysics Data System (ADS)

    Umran, Nibras Mossa; Kumar, Ranjan

    2013-02-01

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

  3. Effect of heavy ion irradiation on C 60

    NASA Astrophysics Data System (ADS)

    Lotha, S.; Ingale, A.; Avasthi, D. K.; Mittal, V. K.; Mishra, S.; Rustagi, K. C.; Gupta, A.; Kulkarni, V. N.; Khathing, D. T.

    1999-06-01

    Thin films of C 60 were subjected to swift heavy ion irradiation spanning the region from 2 to 11 keV/nm of electronic excitation. Studies of the irradiated films by Raman spectroscopy indicated polymerization and damage of the film with an ion fluence. The ion track radii are estimated for various ions using the Raman data. Photoluminescence spectroscopy of the irradiated film indicated a decrease in the C 60 phase with a dose, and an increase in the intensity at the 590 nm wavelength, which is attributed to an increase in the oxygen content.

  4. Optical limiting in C60 and C70 solutions

    NASA Astrophysics Data System (ADS)

    Mishra, S. R.; Rawat, H. S.; Joshi, Mukesh P.; Mehendale, S. C.; Rustagi, Kailash C.

    1994-11-01

    We present experimental results on optical limiting in C60 and C70 solutions in various organic solvents using 30 ns pulses at 527 nm. Angular and temporally resolved measurements of transmitted light and the solvent dependence of optical limiting suggest that in C60 solutions the optical limiting is dominantly of thermal origin. Results of z-scan are presented which show contribution to limiting action from nonlinear refraction as well as scattering. The relevance of these findings to DFWM experiments with visible laser pulses is also discussed.

  5. 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.

  6. The effect of glass transition in fullerite C60 on Ar impurity diffusion

    NASA Astrophysics Data System (ADS)

    Dolbin, A. V.; Esel'son, V. B.; Gavrilko, V. G.; Manzhelii, V. G.; Vinnikov, N. A.; Basnukaeva, R. M.

    2013-04-01

    The kinetics of sorption and subsequent desorption of argon gas by powdered fullerite C60 has been investigated in the temperature interval 58-290 K. The temperature dependence of the Ar diffusion coefficients in fullerite has been obtained using measured characteristic times of sorption. The diffusion coefficients for Ar decrease monotonically with decreasing temperature in the entire temperature range, which corresponds to the thermally activated diffusion of Ar atoms in fullerite. The glass transition in fullerite induces an order-of magnitude decrease in the activation energy of Ar diffusion in fullerite. This appears to be due to new paths that appeared as a result of the glass transition, in which the barriers separating the interstitial voids in the C60 lattice are significantly lower.

  7. Oxygen-Induced Degradation in C60-Based Organic Solar Cells: Relation Between Film Properties and Device Performance.

    PubMed

    Bastos, João P; Voroshazi, Eszter; Fron, Eduard; Brammertz, Guy; Vangerven, Tim; Van der Auweraer, Mark; Poortmans, Jef; Cheyns, David

    2016-04-20

    Fullerene-based molecules are the archetypical electron-accepting materials for organic photovoltaic devices. A detailed knowledge of the degradation mechanisms that occur in C60 layers will aid in the development of more stable organic solar cells. Here, the impact of storage in air on the optical and electrical properties of C60 is studied in thin films and in devices. Atmospheric exposure induces oxygen-trap states that are 0.19 eV below the LUMO of the fullerene C60. Moreover, oxygen causes a 4-fold decrease of the exciton lifetime in C60 layers, resulting in a 40% drop of short-circuit current from optimized planar heterojunction solar cells. The presence of oxygen-trap states increases the saturation current of the device, resulting in a 20% loss of open-circuit voltage. Design guidelines are outlined to improve air stability for fullerene-containing devices.

  8. Detection of C60 and C70 in a young planetary nebula.

    PubMed

    Cami, Jan; Bernard-Salas, Jeronimo; Peeters, Els; Malek, Sarah Elizabeth

    2010-09-01

    In recent decades, a number of molecules and diverse dust features have been identified by astronomical observations in various environments. Most of the dust that determines the physical and chemical characteristics of the interstellar medium is formed in the outflows of asymptotic giant branch stars and is further processed when these objects become planetary nebulae. We studied the environment of Tc 1, a peculiar planetary nebula whose infrared spectrum shows emission from cold and neutral C60 and C70. The two molecules amount to a few percent of the available cosmic carbon in this region. This finding indicates that if the conditions are right, fullerenes can and do form efficiently in space.

  9. Dynamics and phase transitions in A 1C 60 compounds

    NASA Astrophysics Data System (ADS)

    Schober, H.; Renker, B.; Heid, R.; Tölle, A.

    1997-02-01

    We present an overview of extensive inelastic neutron scattering experiments carried out on powders of A 1C 60. The various phases leave strong fingerprints in the microscopic dynamics confirming the solid-state chemical reactions. The strong kinetic phase transitions can be followed in real time and turn out to be highly complex.

  10. Investigation of optical limiting in C60 solution

    NASA Astrophysics Data System (ADS)

    Joshi, M. P.; Mishra, S. R.; Rawat, H. S.; Mehendale, S. C.; Rustagi, K. C.

    1993-04-01

    Experimental and theoretical studies of optical limiting for 30 ns pulses at 527 nm in C60 are reported. The results indicate that the optical limiting action may involve contribution from other nonlinear loss mechanisms in addition to increased absorption from the photoexcited triplet state.

  11. Molecular depth profiling in ice matrices using C 60 projectiles

    NASA Astrophysics Data System (ADS)

    Wucher, A.; Sun, S.; Szakal, C.; Winograd, N.

    2004-06-01

    The prospects of molecular sputter depth profiling using C 60+ projectiles were investigated on thick ice layers prepared by freezing aqueous solutions of histamine onto a metal substrate. The samples were analyzed in a ToF-SIMS spectrometer equipped with a liquid metal Ga + ion source and a newly developed fullerene ion source. The C 60+ beam was used to erode the surface, while static ToF-SIMS spectra were taken with both ion beams alternatively between sputtering cycles. We find that the signals both related to the ice matrix and to the histamine are about two orders of magnitude higher under 20-keV C 60 than under 15-keV Ga bombardment. Histamine related molecular signals are found to increase drastically if the freshly introduced surface is pre-sputtered with C 60 ions, until at a total ion fluence of about 10 13 cm -2 the spectra are completely dominated by the molecular ion and characteristic fragments of histamine. At larger fluence, the signal is found to decrease with a disappearance cross section of approximately 10 -14 cm 2, until at total fluences of about 10 14 cm -2 a steady state with stable molecular signals is reached. In contrast, no appreciable molecular signal could be observed if Ga + ions were used to erode the surface.

  12. Spin-based diagnostic of nanostructure in copper phthalocyanine-C60 solar cell blends.

    PubMed

    Warner, Marc; Mauthoor, Soumaya; Felton, Solveig; Wu, Wei; Gardener, Jules A; Din, Salahud; Klose, Daniel; Morley, Gavin W; Stoneham, A Marshall; Fisher, Andrew J; Aeppli, Gabriel; Kay, Christopher W M; Heutz, Sandrine

    2012-12-21

    Nanostructure and molecular orientation play a crucial role in determining the functionality of organic thin films. In practical devices, such as organic solar cells consisting of donor-acceptor mixtures, crystallinity is poor and these qualities cannot be readily determined by conventional diffraction techniques, while common microscopy only reveals surface morphology. Using a simple nondestructive technique, namely, continuous-wave electron paramagnetic resonance spectroscopy, which exploits the well-understood angular dependence of the g-factor and hyperfine tensors, we show that in the solar cell blend of C(60) and copper phthalocyanine (CuPc)-for which X-ray diffraction gives no information-the CuPc, and by implication the C(60), molecules form nanoclusters, with the planes of the CuPc molecules oriented perpendicular to the film surface. This information demonstrates that the current nanostructure in CuPc:C(60) solar cells is far from optimal and suggests that their efficiency could be considerably increased by alternative film growth algorithms.

  13. Thermopower of benzenedithiol and C60 molecular junctions with Ni and Au electrodes.

    PubMed

    Lee, See Kei; Ohto, Tatsuhiko; Yamada, Ryo; Tada, Hirokazu

    2014-09-10

    We have performed thermoelectric measurements of benzenedithiol (BDT) and C60 molecules with Ni and Au electrodes using a home-built scanning tunneling microscope. The thermopower of C60 was negative for both Ni and Au electrodes, indicating the transport of carriers through the lowest unoccupied molecular orbital in both cases, as was expected from the work functions. On the other hand, the Ni-BDT-Ni junctions exhibited a negative thermopower, whereas the Au-BDT-Au junctions exhibited a positive thermopower. First-principle calculations revealed that the negative thermopower of Ni-BDT-Ni junctions is due to the spin-split hybridized states generated by the highest occupied molecular orbital of BDT coupled with s- and d-states of the Ni electrode. PMID:25141337

  14. Microscopic dynamics of an amorphous C60 x /C70(1 - x) fullerene mixture

    NASA Astrophysics Data System (ADS)

    Khusnutdinoff, R. M.; Mokshin, A. V.; Takhaviev, I. D.

    2015-02-01

    This paper presents the results of investigation of the propagation mechanism of collective excitations in amorphous C60 x /C70(1 - x) fullerene mixtures (with equimolar concentration x = 0.50), which were obtained using molecular dynamics simulation. The critical glass-transition temperature of the system T c = 1548 K was determined from the change in the behavior of the Wendt-Abraham parameter. Spectral densities of the time correlation functions of the longitudinal and transverse currents for a wide region of wave numbers at temperatures below the glass-transition temperature were calculated. It was found that the dynamics of density fluctuations in amorphous C60 x /C70(1 - x) fullerene mixtures is characterized by two dispersion acoustic-like branches of the longitudinal and transverse polarizations. The influence of poly-dispersity and form factor of the molecule of the mixture component on the microscopic dynamics of the density fluctuation in multicomponent systems was established.

  15. Kramers-Kronig relation between nonlinear absorption and refraction of C(60) and C(70).

    PubMed

    Wu, Chen-Cheng; Liu, Tai-Min; Wei, Tai-Ying; Xin, Li; Li, Yi-Ci; Lee, Li-Shu; Chang, Che-Kai; Tang, Jaw-Luen; Yang, Sidney S; Wei, Tai-Huei

    2010-10-25

    Using the Z-scan technique with 532 nm 16 picosecond laser pulses, we observe reverse saturable absorption and positive nonlinear refraction of toluene solutions of both C(60) and C(70). By deducting the positive Kerr nonlinear refraction of the solvent, we notice that the solute molecules contribute to nonlinear refraction of opposite signs: positive for C(60) and negative for C(70). Attributing nonlinear absorption and refraction of both solutes to cascading one-photon excitations, we illustrate that they satisfy the Kramers-Kronig relation. Accordingly, we attest the signs and magnitudes of nonlinear refraction for both solutes at 532 nm by Kramers-Kronig transform of the corresponding nonlinear absorption spectra.

  16. (CH3Br⋯NH3)@C60: The effect of nanoconfinement on halogen bonding

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

    Halogen bonds resemble hydrogen bonds in many aspects. How do the properties of halogen bonds change when confined to nanoregion? In order to explore this, we have encapsulated a halogen bonded complex, CH3Br⋯NH3 inside C60 fullerene and studied their properties using density functional theory and quantum theory of atoms in molecule. Our findings show that the geometry of CH3Br⋯NH3 complex is appreciably bent inside C60, interaction becomes covalent with larger interaction energy, unlike free CH3Br⋯NH3 complex, which is linear with closed shell interaction. Thus, the halogen bonded complexes show quite different properties at nanoscale.

  17. Surface Studies of C60 on Ferromagnetic Nickel/Copper(100) and Cobalt/Ruthenium(0001) Thin Film Systems

    NASA Astrophysics Data System (ADS)

    Cummings, Marvin L., Jr.

    reveal any affect of Co on the local magnetic properties of Co. However, an internal structure of C60 molecules adsorbed on the Co(0001) film surface was observed, corresponding to a 3-fold (symmetry) molecular-orientation; and in the near-region where C60 clusters were adsorbed, Co surface state peaks were observed to be absent, suggesting the local electronic structure of Co is perturbed by the presence of C60.

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

    NASA Astrophysics Data System (ADS)

    Onoe, Jun; Nakao, Aiko; Hara, Toshiki

    2004-12-01

    The interaction between C60 and Si atoms has been investigated for Si atoms adsorbed on a C60 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 (SiOx), bulk Si crystal, and silicon atoms bound to C60. Based on the atomic percent ratio of silicon to carbon, we estimated that there was approximately one Si atom bound to each C60 molecule. The Si 2p peak due to the Si-C60 interaction demonstrated that a charge transfer from the Si atom to the C60 molecule takes place at room temperature, which is much lower than the temperature of 670 K at which the charge transfer was observed for C60 adsorbed on Si(001) and (111) clean surfaces [Sakamoto et al., Phys. Rev. B 60, 2579 (1999)]. The number of electrons transferred between the C60 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 C60Si with C2v 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 C60Si 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-C60 interaction was also discussed in terms of Mulliken overlap population between them.

  19. 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.

  20. First-principles calculations of Fe-doped monolayer C60 on h-BN/Ni(111) surface

    NASA Astrophysics Data System (ADS)

    Li, Lan; Wu, Yu-Ning; Cheng, Hai-Ping

    2010-02-01

    We have used large-scale first-principles calculations based on density functional theory to investigate the structure, energetics, electronic, and magnetic structures of Fen-doped C60 monolayers supported by h-BN monolayer-covered Ni(111) surfaces. A systematic study of n-dependent physical properties has been performed (n =1-4,15). Binding energies on Fe atoms to the Fen-1-C60 complex have been calculated for n =1-4 after a thorough configuration search and structural optimization. The binding energy, electron charge transfer (from Fen to C60), and magnetic moment all increase monotonically as functions of n. The electron charge transfer, ranging from ˜1e- to 5e-, is from the spin minority population. This leads to a situation in which the net spin of the C60 molecule aligns with the spin minority and the magnetic moment in C60 is opposite to the total magnetic moment of the system. For n =2, a competing antiferromagnetic state has been found. In this state, the net spin of the system as well as the C60 is zero. Density of states and projected density of states analysis indicate that the system becomes metallic upon metal doping regardless its magnetic state. In addition, we have also performed calculations with the Hubbard U term (DFT+U) for two systems, n =4 and 15, to investigate possible gap opening near the Fermi surface.

  1. 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.

  2. Effect of Water Hydrogen Bonding on the Solvent-Mediated "Oscillatory" Repulsion of C60 Fullerenes in Water.

    PubMed

    Djikaev, Yuri S; Ruckenstein, Eli

    2015-05-01

    The solvent-mediated interaction of C60 fullerenes in liquid water is examined by using the combination of the probabilistic hydrogen bond model with the density functional theory. This combination allows one to take into account the effect of hydrogen bonding between water molecules on their interaction with fullerenes and to construct an approximation for the distribution of water molecules in the system, which provides an efficient foundation for studying hydrophobic phenomena. Our numerical evaluations predict the solvent-induced interaction of two C60 fullerenes in water at 293 K to have an oscillatory-repulsive character (previously observed in molecular dynamics simulations) only when the vicinal water-water hydrogen bonds are slightly weaker than bulk ones. Besides indicating the direction of the energetic alteration of water-water hydrogen bonds near C60 fullerenes, our model also suggests that the hydrogen bonding ability of water plays a defining role in the solvent-mediated C60-C60 repulsion. PMID:26263346

  3. Morphology Change of C60 Islands on Organic Crystals Observed by Atomic Force Microscopy.

    PubMed

    Freund, Sara; Hinaut, Antoine; Pawlak, Rémy; Liu, Shi-Xia; Decurtins, Silvio; Meyer, Ernst; Glatzel, Thilo

    2016-06-28

    Organic-organic heterojunctions are nowadays highly regarded materials for light-emitting diodes, field-effect transistors, and photovoltaic cells with the prospect of designing low-cost, flexible, and efficient electronic devices.1-3 However, the key parameter of optimized heterojunctions relies on the choice of the molecular compounds as well as on the morphology of the organic-organic interface,4 which thus requires fundamental studies. In this work, we investigated the deposition of C60 molecules at room temperature on an organic layer compound, the salt bis(benzylammonium)bis(oxalato)cupurate(II), by means of noncontact atomic force microscopy. Three-dimensional molecular islands of C60 having either triangular or hexagonal shapes are formed on the substrate following a "Volmer-Weber" type of growth. We demonstrate the dynamical reshaping of those C60 nanostructures under the local action of the AFM tip at room temperature. The dissipated energy is about 75 meV and can be interpreted as the activation energy required for this migration process.

  4. Density functional study of structural and electronic properties of Aln@C60

    NASA Astrophysics Data System (ADS)

    Dhiman, Shobhna; Kumar, Ranjan; Dharamvir, Keya

    2014-04-01

    Fullerene derivatives have been shown to make contributions in many types of applications. Ab initio investigation of structural and electronic properties of aluminum doped endohedral fullerene has been performed using numerical atomic orbital density functional theory. We have obtained ground state structures for Aln@C60 (n=1-10). Which shows that C60 molecule can accommodate maximum of nine aluminum atoms, for n > 9 the cage eventually break. Encapsulated large number of aluminum atoms leads to deformation of cage with diameter varies from 7.16Å to 7.95Å. Binding energy/Al atom is found to increase till n = 4 and after that it decreases with the number of Al atoms with a sudden increase for n=10 due to breakage of C60 cage and electronic affinity first increases till n=4 then it decreases up to n=9 with a sharp increase for n=10. Ionization potential also first increases and then decreases. Homo-Lumo gap decreases till n=3 with a sharp increase for n=4, after that it shows an oscillatory nature. The results obtained are consistent with available theoretical and experimental results. The ab-initio calculations were performed using SIESTA code with generalized gradient approximation (GGA).

  5. Morphology Change of C60 Islands on Organic Crystals Observed by Atomic Force Microscopy.

    PubMed

    Freund, Sara; Hinaut, Antoine; Pawlak, Rémy; Liu, Shi-Xia; Decurtins, Silvio; Meyer, Ernst; Glatzel, Thilo

    2016-06-28

    Organic-organic heterojunctions are nowadays highly regarded materials for light-emitting diodes, field-effect transistors, and photovoltaic cells with the prospect of designing low-cost, flexible, and efficient electronic devices.1-3 However, the key parameter of optimized heterojunctions relies on the choice of the molecular compounds as well as on the morphology of the organic-organic interface,4 which thus requires fundamental studies. In this work, we investigated the deposition of C60 molecules at room temperature on an organic layer compound, the salt bis(benzylammonium)bis(oxalato)cupurate(II), by means of noncontact atomic force microscopy. Three-dimensional molecular islands of C60 having either triangular or hexagonal shapes are formed on the substrate following a "Volmer-Weber" type of growth. We demonstrate the dynamical reshaping of those C60 nanostructures under the local action of the AFM tip at room temperature. The dissipated energy is about 75 meV and can be interpreted as the activation energy required for this migration process. PMID:27219352

  6. 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%.

  7. Intensity-resolved IR multiple photon ionization and fragmentation of C60.

    PubMed

    Bakker, Joost M; Lapoutre, Vivike J F; Redlich, Britta; Oomens, Jos; Sartakov, Boris G; Fielicke, André; von Helden, Gert; Meijer, Gerard; van der Meer, Alexander F G

    2010-02-21

    The sequential absorption of multiple infrared (IR) photons by isolated gas-phase species can lead to their dissociation and/or ionization. Using the newly constructed "Free-Electron Laser for IntraCavity Experiments" (FELICE) beam line at the FELIX facility, neutral C(60) molecules have been exposed to an extremely high number (approximately 10(23)) of photons/cm(2) for a total time duration of up to 5 micros. At wavelengths around 20 microm, resonant with allowed IR transitions of C(60), ionization and extensive fragmentation of the fullerenes are observed. The resulting photofragment distributions are attributed to absorption in fragmentation products formed once C(60) is excited to internal energies at which fragmentation or ionization takes place within the duration of the laser pulse. The high IR intensities available combined with the large interaction volume permit spatially resolved detection of the ions inside the laser beam, thereby disentangling the contributions from different IR intensities. The use of spatial imaging reveals intensity dependent mass distributions that are substantially narrower than what has been observed previously, indicating rather narrow energy distributions. A simple rate-equation modeling of the excitation process supports the experimental observations.

  8. Zero-field splitting of the lowest excited triplet states of C(60) and C(70) and benzene.

    PubMed

    van Gastel, Maurice

    2010-10-14

    The electronic structure of the lowest excited triplet states of C(60) and C(70) are characterized by a magnetic interaction between the unpaired electrons for which the zero-field-splitting parameter D is negative for the former and positive for the latter molecule. The sign of D has so far been qualitatively understood, and its magnitude has been found to critically depend on the degree of delocalization of the singly occupied molecular orbitals. In this contribution, the effect of spin polarization to the zero-field-splitting parameters of the fullerenes is evaluated, the inclusion of which results in quantitative agreement between the experimental and calculated D values. The direct spin-spin contribution is found to be dominant for both molecules. For C(60), a significant contribution of 20% of the total zero-field splitting has been found to derive from spin polarization. The physical reason for the sign difference of D for C(60) and C(70) is traced back to the relative phases of the local p(z) orbitals of adjacent carbon atoms near the equatorial plane in both singly occupied molecular orbitals. These relative phases differ for C(60) and C(70), because C(70) has an additional set of ten carbon atoms in its equatorial plane as compared to C(60). Additionally, the triplet wave function of C(70) is found to contain significant multireference character. In order to evaluate the effect of spin polarization in multireference systems, the zero-field-splitting parameters of the lowest triplet state of benzene have been evaluated in an illustrative and insightful calculation as well. Though this prototypical molecule is much smaller than C(60) and C(70), the electronic structure of its lowest excited triplet state is also of multireference character. For benzene, 18% of the total zero-field splitting arises from spin polarization.

  9. 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.

  10. 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

  11. Electronic structures and optical properties of the IPR-violating C60X8 (X = H, F, and Cl) fullerene compounds: a computational study.

    PubMed

    Tang, Shu-Wei; Wang, Feng-Di; Zhang, Nan-Nan; Chang, Ying-Fei; Sun, Hao; Zhang, Jing-Ping; Xie, Hai-Ming; Qiu, Yong-Qing; Wang, Rong-Shun

    2012-12-21

    Stimulated by the preparation and characterization of the isolated pentagon rule (IPR) violating chlorofullerene: C(60)Cl(8) (Nat. Mater. 2008, 7, 790-794), we have performed a systematic investigation on the structural stabilities, electronic and optical properties of the IPR-violating C(60)X(8) (X = H, F, and Cl) fullerene compounds via density functional theory. The large energy gaps between the highest occupied and the lowest unoccupied molecular orbitals provide a clear indication of high chemical stabilities of C(60)X(8) derivatives, and moreover, the C(60)X(8) molecules present great aromatic character with the negative nucleus independent chemical shift values. In the addition reactions of C(60) (C(2v)) + 4X(2) → C(60)X(8), a series of exothermic processes are involved, with high reaction energies ranging from -71.97 to -233.16 kcal mol(-1). An investigation on the electronic property shows that C(60)F(8) and C(60)Cl(8) could be excellent electron acceptors as a consequence of large vertical electron affinities. The density of state analysis suggests that the frontier molecular orbitals of C(60)X(8) are mainly from the carbon orbitals of two separate annulene subunits, and the influence from X atoms is secondary. In addition, the ultraviolet-visible spectra and second-order hyperpolarizabilities of C(60)X(8) are calculated by means of time-dependent density functional theory and a finite field approach, respectively. Both the average static linear polarizability <α> and second-order hyperpolarizability <γ> of C(60)X(8) increase greatly compared to those of C(60).

  12. Thermal conductivity of hard carbon prepared from C 60 fulleren

    NASA Astrophysics Data System (ADS)

    Smontara, A.; Biljaković, K.; Starešinić, D.; Pajić, D.; Kozlov, M. E.; Hirabayashi, M.; Tokumoto, M.; Ihara, H.

    1996-02-01

    We report measurements of thermal conductivity in 30-350 K range of hard fullerene-based carbon. The material has been prepared from C 60 fullerene under pressure and has an unusual combination of large hardness and relatively high electrical conductivity. Its thermal conductivity is about 5.5 W/mk at room temperature and decreases almost linearly in the investigated temperature range. The data obtained bear resemblance to the thermal properties of amorphous materials. It is consistent with the structural investigation that allows one to suggest the existence of short-range crystalline order in this transformed substance.

  13. Tuning the depth of bowl-shaped phosphine hosts: capsule and pseudo-cage architectures in host-guest complexes with C60 fullerene.

    PubMed

    Yamamura, Masaki; Sukegawa, Kimiya; Nabeshima, Tatsuya

    2015-08-01

    Bowl-shaped phosphine molecules, whose bowl geometry can be controlled by a variation of the axial substituent, were synthesized, and used as host molecules to encapsulate C60. Host molecules with relatively shallow bowls formed a chiral capsule, while hosts with deeper bowls formed an achiral pseudo-cage. PMID:26120943

  14. Self-stability of C60 nanocapsules with radio-iodide content and its interaction with calcium atoms.

    PubMed

    Valderrama, Alejandro; Reynoso, Radamés; Gómez, Raúl W; Marquina, Vivianne

    2016-01-01

    This paper inquires the C60 capabilities to contain radio-iodide ((131)I2) molecules. The encapsulation conditions are investigated applying first principles method to simulate with geometric optimizations and molecular dynamics at 310 K and atmospheric pressure. We find that the n(131)I2@C60 system, where n = 1, 2, 3…, is stable if the content does not exceed three molecules of radio-iodide. The application of density functional theory allows us to determine that, the nanocapsules content limit is related with the amount of charge that is transferred from the iodine (131)I2 molecules to the carbon atoms in the fullerene surface. The Mulliken population analysis reveals that the excess of charge increases the repulsive forces between atoms and the bond length average in the C60 structure. The weakened bonds easily break and will critically damage the encapsulation properties. Additionally, we test the interaction nanocapsules with different amounts of radioactive iodine diatomic molecules content with calcium atoms, and find that only the fullerene containing one radioactive iodine diatomic molecule was able to interact with up to nine atoms of calcium without disrupting or cracking. Other fullerenes with two and three radio iodine diatomic molecules cannot resist the interaction with a single calcium atom without cracking or being broken.

  15. Eigenvectors of internal vibrations of C60: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Heid, R.; Pintschovius, L.; Godard, J. M.

    1997-09-01

    We have studied the eigenvectors of all internal modes of C60 up to 75 meV by inelastic neutron scattering. The experimental data are compared in detail with a state-of-the-art ab initio theory and a phenomenological model of the vibrational spectrum of C60, respectively. We demonstrate that the momentum dependence of mode intensities obtained from measurements on single crystals as well as on powder samples represents a sensitive fingerprint of the eigenvectors which allows (i) unambiguous assignments of silent modes and (ii) discrimination of eigenvectors of modes belonging to the same symmetry class. The latter property can be used for stringent tests of theoretical models. Eigenvectors predicted by the ab initio theory are found to be in very satisfactory agreement with the experimental data, while those obtained from the phenomenological model turn out to be less reliable. We have also performed measurements to study the dispersion of the Hg(1) mode in the low-temperature phase. We found that the data can be largely, although not fully, understood on the basis of a simple van der Waals ansatz for the intermolecular interactions.

  16. 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)

  17. Dual electron transfer pathways from the excited C60 radical anion: enhanced reactivities due to the photoexcitation of reaction intermediates.

    PubMed

    Fujitsuka, Mamoru; Ohsaka, Tatsuya; Majima, Tetsuro

    2015-12-14

    In the present study, electron transfer (ET) processes from excited radical anions have been investigated using dyad molecules including C60. The deactivation process of excited C60˙(-), including the internal conversion from the D1 to the D0 state and the cooling process of the vibrationally hot ground state (D), was observed spectroscopically for the first time. These processes could be unambiguously distinguished by the observation of the stimulated emission from the D1 state. The intramolecular ET processes from the excited C60˙(-) were confirmed by the transient absorption spectra. Clearly, both D1 and D states acted as precursors for the ET, i.e., dual ET pathways were confirmed. The driving force dependence of the ET rates was well characterized by the Marcus theory, which revealed that the forward ET processes are located at the top region of the Marcus parabola. In addition, the ET from the excited imide radical anion to C60 and that from the ground state C60˙(-) to imide were examined. The ET rate from the excited imide radical anion and that from ground state C60˙(-) did not follow the Marcus parabola estimated for the ET from the excited C60˙(-). The observed difference can be attributed to the difference in the energy required to form the reduced spacer (Δ) in the superexchange mechanism. Because the Δ value tends to become smaller for ET processes from excited radical ions, fast and efficient ET processes are expected from these states as demonstrated in the present study.

  18. Continuum modeling investigation of gigahertz oscillators based on a C60 fullerene inside cyclic peptide nanotubes

    NASA Astrophysics Data System (ADS)

    Sadeghi, F.; Ansari, R.; Darvizeh, M.

    2016-02-01

    Research concerning the fabrication of nano-oscillators with operating frequency in the gigahertz (GHz) range has become a focal point in recent years. In this paper, a new type of GHz oscillators is introduced based on a C60 fullerene inside a cyclic peptide nanotube (CPN). To study the dynamic behavior of such nano-oscillators, using the continuum approximation in conjunction with the 6-12 Lennard-Jones (LJ) potential function, analytical expressions are derived to determine the van der Waals (vdW) potential energy and interaction force between the two interacting molecules. Employing Newton's second law, the equation of motion is solved numerically to arrive at the telescopic oscillatory motion of a C60 fullerene inside CPNs. It is shown that the fullerene molecule exhibits different kinds of oscillation inside peptide nanotubes which are sensitive to the system parameters. Furthermore, for the precise evaluation of the oscillation frequency, a novel semi-analytical expression is proposed based on the conservation of the mechanical energy principle. Numerical results are presented to comprehensively study the effects of the number of peptide units and initial conditions (initial separation distance and velocity) on the oscillatory behavior of C60 -CPN oscillators. It is found out that for peptide nanotubes comprised of one unit, the maximum achievable frequency is obtained when the inner core oscillates with respect to its preferred positions located outside the tube, while for other numbers of peptide units, such frequency is obtained when the inner core oscillates with respect to the preferred positions situated in the space between the two first or the two last units. It is further found out that four peptide units are sufficient to obtain the optimal frequency.

  19. 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

  20. Structural influence on Raman scattering of a new C60 thin film prepared by AAO template with the method of pressure difference.

    PubMed

    Zhixun, Luo; Yan, Fang

    2006-01-01

    An anodic aluminum oxide (AAO) template is prepared by anodizing aluminum in oxalic acid solution. C60 crystals were grown, using the pressure difference method, in the pores of the template, representing a brushlike thin film layer with a honeycomb boundary structure in one side and nail arrays in the other side. Different Raman spectra of the C60 thin film from the both sides are presented, which indicate the different uniformly ordered structure character and the interface behavior of the C60 film on the surface with C60 crystals in the AAO nanopores. On the basis of energy and group theory, the strengthening of the Raman intensity and the broadening of Raman modes may imply that more transition spectral lines between vibration or rotation energy levels of C60 molecules were excited and detected.

  1. Charge separated states and singlet oxygen generation of mono and bis adducts of C60 and C70

    NASA Astrophysics Data System (ADS)

    Dallas, Panagiotis; Rogers, Gregory; Reid, Ben; Taylor, Robert A.; Shinohara, Hisanori; Briggs, G. Andrew D.; Porfyrakis, Kyriakos

    2016-02-01

    We present a series of fullerene derivatives and a study on their photoluminescence properties, complete with their efficiency as singlet oxygen generation photosensitizers. We demonstrate the intramolecular charge transfer between pyrene donor and fullerene acceptor. The opposite effect in decay lifetime measurements is observed for the mono and bis adducts of C60 and C70 for the first time, indicating an interplay between charge-separation and locally excited states. A monoexponential decay was observed for the mono adduct of C60 and the bis adduct of C70, while a biexponential decay was observed for the bis adduct of C60 and the mono adduct of C70. The effect of these molecules as sensitizers of the singlet oxygen radical was tested using detailed 3D excitation photoluminescence maps. A quenching of the singlet oxygen for the C60-mono and C70-bis adducts was observed while a strong photosensitizing effect was observed for the C60-bis and C70-mono adducts.

  2. Symmetry-selected spin-split hybrid states in C60/ferromagnetic interfaces

    NASA Astrophysics Data System (ADS)

    Li, Dongzhe; Barreteau, Cyrille; Kawahara, Seiji Leo; Lagoute, Jérôme; Chacon, Cyril; Girard, Yann; Rousset, Sylvie; Repain, Vincent; Smogunov, Alexander

    2016-02-01

    The understanding of orbital hybridization and spin polarization at the organic-ferromagnetic interface is essential in the search for efficient hybrid spintronic devices. Here, using first-principles calculations, we report a systematic study of spin-split hybrid states of C60 deposited on various ferromagnetic surfaces: bcc-Cr(001), bcc-Fe(001), bcc-Co(001), fcc-Co(001), and hcp-Co(0001). We show that the adsorption geometry of the molecule with respect to the surface crystallographic orientation of the magnetic substrate as well as the strength of the interaction play a crucial role in the spin polarization of the hybrid orbitals. We find that a large spin polarization in vacuum above the buckyball can only be achieved if the molecule is adsorbed upon a bcc-(001) surface by its pentagonal ring. Therefore, bcc-Cr(001), bcc-Fe(001), and bcc-Co(001) are the optimal candidates. Spin-polarized scanning tunneling spectroscopy measurements on single C60 adsorbed on Cr(001) and Co/Pt(111) also confirm that the symmetry both of the substrate and of the molecular conformation has a strong influence on the induced spin polarization. Our finding may give valuable insights for further engineering of spin filtering devices through single molecular orbitals.

  3. 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.

  4. Detection of C60 and C70 in a young planetary nebula.

    PubMed

    Cami, Jan; Bernard-Salas, Jeronimo; Peeters, Els; Malek, Sarah Elizabeth

    2010-09-01

    In recent decades, a number of molecules and diverse dust features have been identified by astronomical observations in various environments. Most of the dust that determines the physical and chemical characteristics of the interstellar medium is formed in the outflows of asymptotic giant branch stars and is further processed when these objects become planetary nebulae. We studied the environment of Tc 1, a peculiar planetary nebula whose infrared spectrum shows emission from cold and neutral C60 and C70. The two molecules amount to a few percent of the available cosmic carbon in this region. This finding indicates that if the conditions are right, fullerenes can and do form efficiently in space. PMID:20651118

  5. Synthesis and characterization of highly photoresponsive fullerenyl dyads with a close chromophore antenna–C60 contact and effective photodynamic potential†

    PubMed Central

    Padmawar, Prashant A.; Rogers-Haley, Joy E.; So, Grace; Canteenwala, Taizoon; Thota, Sammaiah; Tan, Loon-Seng; Pritzker, Kenneth; Huang, Ying-Ying; Sharma, Sulbha K.; Kurup, Divya Balachandran; Hamblin, Michael R.; Wilson, Brian; Urbas, Augustine

    2010-01-01

    We report the synthesis of a new class of photoresponsive C60–DCE–diphenylaminofluorene nanostructures and their intramolecular photoinduced energy and electron transfer phenomena. Structural modification was made by chemical conversion of the keto group in C60(>DPAF-Cn) to a stronger electron-withdrawing 1,1-dicyanoethylenyl (DCE) unit leading to C60(>CPAF-Cn) with an increased electronic polarization of the molecule. The modification also led to a large bathochromic shift of the major band in visible spectrum giving measureable absorption up to 600 nm and extended the photoresponsive capability of C60–DCE–DPAF nanostructures to longer red wavelengths than C60(>DPAF-Cn). Accordingly, C60(>CPAF-Cn) may allow 2γ-PDT using a light wavelength of 1000–1200 nm for enhanced tissue penetration depth. Production efficiency of singlet oxygen by closely related C60(>DPAF-C2M) was found to be comparable with that of tetraphenylporphyrin photosensitizer. Remarkably, the 1O2 quantum yield of C60(>CPAF-C2M) was found to be nearly 6-fold higher than that of C60(>DPAF-C2M), demonstrating the large light-harvesting enhancement of the CPAF-C2M moiety and leading to more efficient triplet state generation of the C60> cage moiety. This led to highly effective killing of HeLa cells by C60(>CPAF-C2M) via photodynamic therapy (200 J cm−2 white light). We interpret the phenomena in terms of the contributions by the extended π-conjugation and stronger electron-withdrawing capability associated with the 1,1-dicyanoethylenyl group compared to that of the keto group. PMID:20890406

  6. Fullerene (C60) nano-colloids in nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Visco, Angelo; Sobczak, Kevin; Mahmood, Rizwan

    2015-03-01

    We report high resolution homodyne light scattering studies to probe director fluctuations in bend/splay mode in bulk nematic liquid crystal and as a function of fullerene (C60) nanoparticles concentration. The preliminary analysis shows that the relaxation time of these fluctuations is fairly constant with in the experimental uncertainty despite the constraints imposed on the director fluctuations due to the insertion of nano colloids. The relaxation time extracted from the data found to be in nano seconds range and the diffusion constant (D) found to be, D = 4.29 x 106 cm/sec. The authors acknowledge the financial support from grants office, Dean, college of Health, Environment & Science and the physics department.

  7. 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

  8. Preparation of C60-functionalized magnetic silica microspheres for the enrichment of low-concentration peptides and proteins for MALDI-TOF MS analysis.

    PubMed

    Chen, Hemei; Qi, Dawei; Deng, Chunhui; Yang, Penyuan; Zhang, Xiangmin

    2009-01-01

    In this work, for the first time, a novel C60-functionalized magnetic silica microsphere (designated C60-f-MS) was synthesized by radical polymerization of C60 molecules on the surface of magnetic silica microspheres. The resulting C60-f-MS microsphere has magnetite core and thin C60 modified silica shell, which endow them with useful magnetic responsivity and surface affinity toward low-concentration peptides and proteins. As a result of their excellent magnetic property, the synthesized C60-f-MS microspheres can be easily separated from sample solution without ultracentrifuge. The C60-f-MS microspheres were successfully applied to the enrichment of low-concentration peptides in tryptic protein digest and human urine via a MALDI-TOF MS analysis. Moreover, they were demonstrated to have enrichment efficiency for low-concentration proteins. Due to the novel materials maintaining excellent magnetic properties and admirable adsorption, the process of enrichment and desalting is very fast (only 5 min), convenient and efficient. As it has been demonstrated in the study, newly developed fullerene-derivatized magnetic silica materials are superior to those already available in the market. The facile and low-cost synthesis as well as the convenient and efficient enrichment process of the novel C60-f-MS microspheres makes it a promising candidate for isolation of low-concentration peptides and proteins even in complex biological samples such as serum, plasma, and urine or cell lysate. PMID:19086100

  9. An ab-initio density functional theory investigation of fullerene/Zn-phthalocyanine (C60/ZnPc) interface with face-on orientation

    SciTech Connect

    Javaid, Saqib; Javed Akhtar, M.

    2015-07-28

    We have employed density functional theory to study the C60/ZnPc interface with face-on orientation, which has recently been tailored experimentally. For this purpose, adsorption of ZnPc on C60 has been studied, while taking into account different orientations of C60. Out of various adsorption sites investigated, 6:6 C-C bridge position in apex configuration of C60 has been found energetically the most favourable one with C60-ZnPc adsorption distance of ∼2.77 Å. The adsorption of ZnPc on C60 ensues both charge re-organization and charge transfer at the interface, resulting in the formation of interface dipole. Moreover, by comparing results with that of C60/CuPc interface, we show that the direction of interface dipole can be tuned by the change of the central atom of the phthalocyanine molecule. These results highlight the complexity of electronic interactions present at the C60/Phthalocyanine interface.

  10. Understanding the electronic structure of CdSe quantum dot-fullerene (C60) hybrid nanostructure for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Sarkar, Sunandan; Rajbanshi, Biplab; Sarkar, Pranab

    2014-09-01

    By using the density-functional tight binding method, we studied the electronic structure of CdSe quantum dot(QD)-buckminsterfullerene (C60) hybrid systems as a function of both the size of the QD and concentration of the fullerene molecule. Our calculation reveals that the lowest unoccupied molecular orbital energy level of the hybrid CdSeQD-C60 systems lies on the fullerene moiety, whereas the highest occupied molecular orbital (HOMO) energy level lies either on the QD or the fullerene depending on size of the CdSe QD. We explored the possibility of engineering the energy level alignment by varying the size of the CdSe QD. With increase in size of the QD, the HOMO level is shifted upward and crosses the HOMO level of the C60-thiol molecule resulting transition from the type-I to type-II band energy alignment. The density of states and charge density plot support these types of band gap engineering of the CdSe-C60 hybrid systems. This type II band alignment indicates the possibility of application of this nanohybrid for photovoltaic purpose.

  11. C60 superstructure and carbide formation on the Al-terminated Al9Co2(001 ) surface

    NASA Astrophysics Data System (ADS)

    Ledieu, J.; Gaudry, É.; de Weerd, M.-C.; Gille, P.; Diehl, R. D.; Fournée, V.

    2015-04-01

    We report the formation of an ordered C60 monolayer on the Al9Co2 (001) surface using scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), x-ray and ultraviolet photoelectron spectroscopy (XPS/UPS), and ab initio calculations. Dosing fullerenes at 300 K results in a disordered overlayer. However, the adsorption of C60 with the sample held between 573-673 K leads to a [4, -2 ∣1 ,3 ] phase. The growth of C60 proceeds with the formation of two domains which are mirror symmetric with respect to the [100] direction. Within each domain, the superstructure unit cell contains six molecules and this implies an area per fullerene equal to 91 Å2. The molecules exhibit two types of contrast (bright and dim) which are bias dependent. The adsorption energies and preferred molecular configuration at several possible adsorption sites have been determined theoretically. These calculations lead to a possible scheme describing the configuration of each C60 in the observed superstructure. Several defects (vacancies, protrusions,…) and domain boundaries observed in the film are also discussed. If the sample temperature is higher than 693 K when dosing, impinging C60 molecules dissociate at the surface, hence leading to the formation of a carbide film as observed by STM and LEED measurements. The formation of Al4C3 domains and the molecular dissociation are confirmed by XPS/UPS measurements acquired at different stages of the experiment. The cluster substructure present at the Al9Co2 (001) surface dictates the carbide domain orientations.

  12. Evaluation of the heats of formation of corannulene and C60 by means of high-level theoretical procedures.

    PubMed

    Karton, Amir; Chan, Bun; Raghavachari, Krishnan; Radom, Leo

    2013-02-28

    In this study, we address the issues associated with predicting usefully accurate heats of formation for moderately-sized molecules such as corannulene and C(60). We obtain a high-level theoretical heat of formation for corannulene through the use of reaction schemes that conserve increasingly larger molecular fragments between the reactants and products. The reaction enthalpies are obtained by means of the high-level, ab initio W1h thermochemical protocol, while accurate experimental enthalpies of formation for the other molecules involved in the reactions are obtained from the Active Thermochemical Tables (ATcT) network. Our best theoretical heat of formation for corannulene (Δ(f)H°(298)[C(20)H(10)(g)] = 485.2 ± 7.9 kJ mol(-1)) differs significantly from the currently accepted experimental value (Δ(f)H°(298)[C(20)H(10)(g)] = 458.5 ± 9.2 kJ mol(-1)), and this suggests that re-examination of the experimental data may be in order. We have used our theoretical heat of formation for corannulene to obtain a predicted heat of formation of C(60) through reactions that involve only corannulene and planar polyacenes. Current experimental values span a range of ~200 kJ mol(-1). Our reaction enthalpies are obtained by means of double-hybrid density functional theory in conjunction with a large quadruple-ζ basis set, while accurate experimental heats of formation (or our theoretical value in the case of corannulene) are used for the other molecules involved. Our best theoretical heat of formation for C(60) (Δ(f)H°(298)[C(60)(g)] = 2521.6 kJ mol(-1)) suggests that the experimental value adopted by the NIST thermochemical database (Δ(f)H°(298)[C(60)(g)] = 2560 ± 100 kJ mol(-1)) should be revised downward.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. Theoretical description of phase coexistence in model C60.

    PubMed

    Costa, D; Pellicane, G; Caccamo, C; Schöll-Paschinger, E; Kahl, G

    2003-08-01

    We have investigated the phase diagram of a pair interaction model of C60 fullerene [L. A. Girifalco, J. Phys. Chem. 96, 858 (1992)], in the framework provided by two integral equation theories of the liquid state, namely, the modified hypernetted chain (MHNC) implemented under a global thermodynamic consistency constraint, and the self-consistent Ornstein-Zernike approximation (SCOZA), and by a perturbation theory (PT) with various degrees of refinement, for the free energy of the solid phase. We present an extended assessment of such theories as set against a recent Monte Carlo study of the same model [D. Costa, G. Pellicane, C. Caccamo, and M. C. Abramo, J. Chem. Phys. 118, 304 (2003)]. We have compared the theoretical predictions with the corresponding simulation results for several thermodynamic properties such as the free energy, the pressure, and the internal energy. Then we have determined the phase diagram of the model, by using either the SCOZA, the MHNC, or the PT predictions for one of the coexisting phases, and the simulation data for the other phase, in order to separately ascertain the accuracy of each theory. It turns out that the overall appearance of the phase portrait is reproduced fairly well by all theories, with remarkable accuracy as for the melting line and the solid-vapor equilibrium. All theories show a more or less pronounced discrepancy with the simulated fluid-solid coexistence pressure, above the triple point. The MHNC and SCOZA results for the liquid-vapor coexistence, as well as for the corresponding critical points, are quite accurate; the SCOZA tends to underestimate the density corresponding to the freezing line. All results are discussed in terms of the basic assumptions underlying each theory. We have then selected the MHNC for the fluid and the first-order PT for the solid phase, as the most accurate tools to investigate the phase behavior of the model in terms of purely theoretical approaches. It emerges that the use of

  18. Generation of charge carriers in C60 films by 100-fs laser pulses with photon energies above and below the mobility edge

    SciTech Connect

    Chekalin, Sergei V; Yartsev, A P; Sundstroem, V

    2001-05-31

    Primary stages of photoinduced processes are studied in C60 films excited by 100-fs laser pulses at wavelengths of 645 and 367 nm, the fraction of excited molecules being no more than several percent. Probing in the broad spectral range from 400 to 1100 nm showed that both charged (cations and electrons) and neutral (excited molecules) components were produced upon irradiation by the laser pulse. For both excitation wavelengths, charge carriers were produced due to direct optical excitation rather than due to singlet-singlet annihilation. Anions were produced with a delay of 10{sup -13} - 10{sup -11} s through electron trapping by C60 molecules. (femtosecond technologies)

  19. Ab initio study of structural and electronic properties of Cun@C60

    NASA Astrophysics Data System (ADS)

    Dhiman, Shobhna; Kumar, Ranjan; Dharamvir, Keya

    2013-06-01

    Ab initio investigation of structural and electronic properties of copper doped endohedral fullerene has been performed using numerical atomic orbital density functional theory. We have obtained the ground state structures for Cun@C60 (n=1-10). Which shows that C60 molecule can accommodate maximum of nine copper atoms, for n > 9 the cage eventually break. Encapsulated large number of copper atoms leads to deformation of cage with diameter varies from 7.00Å to 8.38Å. Binding energy/Cu atom is found to increase till n = 4 and after that it decreases with the number of Cu atoms with a sudden increase for n=10 and electronic affinity increases till n=2 then decreases uniformly till up to n=7 with a further sharp decrease for n=10. Ionization potential and Homo-Lumo gap shows a oscillatory nature. The results obtained are consistent with available theoretical and experimental results. The ab-initio calculations were performed using SIESTA code with generalized gradient approximation (GGA).

  20. 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.

  1. Probing confinement resonances by photoionizing Xe inside a C60+ molecular cage

    NASA Astrophysics Data System (ADS)

    Phaneuf, R. A.; Kilcoyne, A. L. D.; Aryal, N. B.; Baral, K. K.; Thomas, C. M.; Esteves-Macaluso, D. A.; Lomsadze, R.; Gorczyca, T. W.; Ballance, C. P.; Manson, S. T.; Hasoglu, M. F.; Hellhund, J.; Schippers, S.; Müller, A.

    2014-05-01

    Double photoionization accompanied by loss of n C atoms (n = 0 , 2 , 4 , 6) was investigated by merging beams of Xe@C60+ ions and synchrotron radiation and measuring the yields of product ions. The giant 4 d dipole resonance of the caged Xe atom has a prominent signature in the cross section for these product channels, which together account for 6 . 2 +/- 1 . 4 of the total Xe 4 d oscillator strength of 10. Compared to that for a free Xe atom, the oscillator strength is redistributed in photon energy due to multipath interference of outgoing Xe 4 d photoelectron waves that may be transmitted or reflected by the spherical C60+ molecular cage, yielding so-called confinement resonances. The data are compared with an earlier measurement and with theoretical predictions for this single-molecule photoelectron interferometer system. Relativistic R-matrix calculations for the Xe atom in a spherical potential shell representing the fullerene cage show the sensitivity of the interference pattern to the molecular geometry.

  2. Probing confinement resonances by photoionizing Xe inside a C60+ molecular cage

    NASA Astrophysics Data System (ADS)

    Phaneuf, R. A.; Kilcoyne, A. L. D.; Aryal, N. B.; Baral, K. K.; Esteves-Macaluso, D. A.; Thomas, C. M.; Hellhund, J.; Lomsadze, R.; Gorczyca, T. W.; Ballance, C. P.; Manson, S. T.; Hasoglu, M. F.; Schippers, S.; Müller, A.

    2013-11-01

    Double photoionization accompanied by loss of n C atoms (n=0, 2, 4, 6) was investigated by merging beams of Xe@C60+ ions and synchrotron radiation and measuring the yields of product ions. The giant 4d dipole resonance of the caged Xe atom has a prominent signature in the cross section for these product channels, which together account for 6.2 ± 1.4 of the total Xe 4d oscillator strength of 10. Compared to that for a free Xe atom, the oscillator strength is redistributed in photon energy due to multipath interference of outgoing Xe 4d photoelectron waves that may be transmitted or reflected by the spherical C60+ molecular cage, yielding so-called confinement resonances. The data are compared with an earlier measurement and with theoretical predictions for this single-molecule photoelectron interferometer system. Relativistic R-matrix calculations for the Xe atom in a spherical potential shell representing the fullerene cage show the sensitivity of the interference pattern to the molecular geometry.

  3. UV laser desorption of nitric oxide from semiconducting C60/Cu(111)

    NASA Astrophysics Data System (ADS)

    Hoger, T.; Grimmer, D.; Zacharias, H.

    2007-08-01

    The desorption of NO from a well-characterized, epitaxially grown semiconducting C60 surface is reported. Two different channels are identified in the laser desorption. Both channels yield a comparably high desorption cross section of σ1=7.0×10-17 cm2 and σ2=5.5×10-17 cm2 for the first and second channel, respectively. The laser desorbed NO molecules are detected with rovibrational state selectivity by (1+1) REMPI in the A^2Σ^+ to{X}^2 Pi γ-bands. In the first channel the desorbing molecules are highly excited with an average kinetic energy of =174 meV. The rotational population distribution can be fitted by a rotational temperature of Trot=800 K. A rotational translational coupling is observed, with velocities ranging from 1000 m/s for low to 1300 m/s for high rotational states. The vibrationally excited population is estimated to be less than 1% of the ground state. The second channel yields less excited molecules and an almost Boltzmann distributed rotational population with a temperature of Trot=280 K. The apparent velocity distribution derived from the pump-probe delay yields molecules much too slow to be explained by even a thermal desorption. This desorption is probably caused by a long-lived electronic excitation in the substrate for which a lifetime of τ≈160 μs is estimated.

  4. 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.

  5. Effect of nitrogen sorption mechanisms on the properties of fullerite C60 over a wide range of temperatures

    NASA Astrophysics Data System (ADS)

    Legchenkova, I. V.; Yagotintsev, K. A.; Galtsov, N. N.; Meleshko, V. V.; Stetsenko, Yu. E.; Prokhvatilov, A. I.

    2014-08-01

    X-ray diffractometry is used to study the effect of the adsorption of nitrogen at a pressure of 30 atm and temperatures of 200-550 °C on the structural and thermodynamic properties of fullerite C60. The sorption kinetics of nitrogen at different temperatures are studied, and the lattice parameter is plotted as a function of the time for fullerite to saturate with nitrogen. The sorption mechanism is found to change with increasing saturation temperature. The diffusive filling of lattice octahedral voids by nitrogen atoms at temperatures below 450 °C is supplanted at higher temperatures by a chemical interaction of nitrogen with fullerite molecules leading to the formation of a new molecular compound, fullerite nitride C60Nx. The transition from physisorption to chemisorption of nitrogen by fullerite (the adsorption crossover) takes place at saturation temperatures of 450 > T > 400 °C. When C60 molecules are nitrogenated, the volume of the cubic cell increases dramatically, while the intensity of the x-ray reflections decreases and their width increases rapidly. The limiting distortions of the fcc lattice are determined, as well as the characteristic times for diffusional filling of the lattice voids and for nitrogenation, respectively, during physical and chemical sorption of nitrogen. Nitrogenation of fullerite molecules leads to a significant reduction in thermal expansion of the crystalline material, and suppresses both the orientational phase transition and formation of the glassy state.

  6. A surface enhanced Raman spectroscopy study of aminothiophenol and aminothiophenol-C60 self-assembled monolayers: Evolution of Raman modes with experimental parameters

    NASA Astrophysics Data System (ADS)

    Delafosse, G.; Merlen, A.; Clair, S.; Patrone, L.

    2012-05-01

    P-aminothiophenol (PATP) is a well-known molecule for the preparation of self-assembled monolayers on gold via its thiol functional group. After adsorption, it has been demonstrated that this molecule is anchored to gold through its thiol group, and standing nearly upright at the surface with the amino functional group on top. This molecule has been extensively studied by surface enhanced Raman spectroscopy but its exact SERS spectrum remains unclear. Here, we demonstrate that it can be strongly affected by at least two experimental parameters: laser power and layer density. Those features are discussed in terms of a dimerization of the PATP molecules. The free amino group affords the adsorption of other molecules such as C60. In this case, a complex multilayer system is formed and the question of its precise characterisation remains a key point. In this article, we demonstrate that surface enhanced Raman spectroscopy combined with x ray photoelectron spectroscopy can bring very important information about the organization of such a self-assembled multilayer on gold. In our study, the strong evolution of Raman modes after C60 adsorption suggests a change in the organization of aminothiophenol molecules during C60 adsorption. These changes, also observed when the aminothiophenol layer is annealed in toluene, do not prevent the adsorption of C60 molecules.

  7. Hydrogen adsorption on Pd- and Ru-doped C60 fullerene at an ambient temperature.

    PubMed

    Saha, Dipendu; Deng, Shuguang

    2011-06-01

    Palladium- and ruthenium-doped C(60) fullerene compounds were synthesized by incipient wetness impregnation of C(60) fullerene with the corresponding metal acetylacetonate precursors. Transmission electron microscopy (TEM) imaging of the metal-doped C(60) fullerene samples showed different dispersion morphologies of palladium and ruthenium particles on the C(60) matrix. Raman spectra revealed a drastic decrease in peak intensity followed by disappearance of several bands indicating the distortion of the C(60) cage structure. The amorphous nature of the C(60) fullerene compounds was confirmed by the X-ray diffraction study. Hydrogen adsorption amount of 0.85 wt % and 0. 69 wt % on Pd-C(60) and Ru-C(60), respectively, as compared to 0.3 wt % on the pure C(60) fullerene were measured at 300 bar and 298 K. The enhancement in the hydrogen uptakes can be attributed to several factors, including adsorption of molecular H(2) on the defect sites, metallic hydride formation, spillover of hydrogen, and bond formation with atomic hydrogen with different active sites of carbon of host fullerene. The hydrogen adsorption isotherms are of type III and can be correlated by the Freundlich (for Ru-C(60)) and modified Oswin equations (for Pd-C(60) and pristine C(60)). PMID:21526804

  8. Synergistic photogeneration of reactive oxygen species by dissolved organic matter and C60 in aqueous phase.

    PubMed

    Li, Yang; Niu, Junfeng; Shang, Enxiang; Crittenden, John Charles

    2015-01-20

    We investigated the photogeneration of reactive oxygen species (ROS) by C60 under UV irradiation, when humic acid (HA) or fulvic acid (FA) is present. When C60 and dissolved organic matter (DOM) were present as a mixture, singlet oxygen ((1)O2) generation concentrations were 1.2–1.5 times higher than the sum of (1)O2 concentrations that were produced when C60 and DOM were present in water by themselves. When C60 and HA were present as a mixture, superoxide radicals (O2(•–)) were 2.2–2.6 times more than when C60 and HA were present in water by themselves. A synergistic ROS photogeneration mechanism involved in energy and electron transfer between DOM and C60 was proposed. Enhanced (1)O2 generation in the mixtures was partly due to (3)DOM* energy transfer to O2. However, it was mostly due to (3)DOM* energy transfer to C60 producing (3)C60*. (3)C60* has a prolonged lifetime (>4 μs) in the mixture and provides sufficient time for energy transfer to O2, which produces (1)O2. The enhanced O2(•–) generation for HA/C60 mixture was because (3)C60* mediated electron transfer from photoionized HA to O2. This study demonstrates the importance of considering DOM when investigating ROS production by C60.

  9. Adsorption and self-assembly of fullerenes on Si(111)√{ 3 } ×√{ 3 }-Ag: C60 versus C70

    NASA Astrophysics Data System (ADS)

    Olyanich, D. A.; Mararov, V. V.; Utas, T. V.; Zotov, A. V.; Saranin, A. A.

    2016-11-01

    Behavior of C60 and C70 fullerenes adsorbed onto Si(111)√{ 3 } ×√{ 3 }-Ag is compared on the basis of STM observations. Such characteristics as sticking coefficient, migration rate, attachment/detachment rate from the molecular islands are considered. Room-temperature sticking coefficient for C70 is slightly greater than that for C60. Due to their non-spherical shape, C70 are less mobile than spherical C60. For both types of fullerenes, mobility of molecules on the fullerene layer is significantly retarded as compared to that on bare Si(111)√{ 3 } ×√{ 3 }-Ag surface. Self-assembly of C60 obeys layer-by-layer growth mode, while C70 follows multi-layer mode, a sign of a greater Ehrlich-Schwoebel barrier. Alternating deposition of C60 and C70 paves the way to fabricate planar C60/C70 heterostructures with the most promising results being obtained with nanostructured islands grown on C60 monomolecular layer.

  10. QM(DFT) and MD studies on formation mechanisms of C60 fullerenes

    NASA Astrophysics Data System (ADS)

    Hua, Xinlei; Cagin, Tahir; Che, Jianwei; Goddard, William A., III

    2000-06-01

    One of the most puzzling aspects of fullerenes is how such complicated symmetric molecules are formed from a gas of atomic carbons, namely, the atomistic or chemical mechanisms. Are the atoms added one by one or as molecules (C2, C3)? Is there a critical nucleus beyond which formation proceeds at gas kinetic rates? What determines the balance between forming buckyballs, buckytubes, graphite and soot? The answer to these questions is extremely important in manipulating the systems to achieve particular products. A difficulty in current experiments is that the products can only be detected on time scales of microseconds long after many of the important formation steps have been completed. Consequently, it is necessary to use simulations, quantum mechanics and molecular dynamics, to determine these initial states. Experiments serve to provide the boundary conditions that severely limit the possibilities. Using quantum mechanical methods (density functional theory (DFT)) we derived a force field (MSXX FF) to describe one-dimensional (rings) and two-dimensional (fullerene) carbon molecules. Combining DFT with the MSXX FF, we calculated the energetics for the ring fusion spiral zipper (RFSZ) mechanism for formation of C60 fullerenes. Our results shows that the RFSZ mechanism is consistent with the quantum mechanics (with a slight modification for some of the intermediates).

  11. Precision printing and optical modeling of ultrathin SWCNT/C60 heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Guillot, Sarah L.; Mistry, Kevin S.; Avery, Azure D.; Richard, Jonah; Dowgiallo, Anne-Marie; Ndione, Paul F.; van de Lagemaat, Jao; Reese, Matthew O.; Blackburn, Jeffrey L.

    2015-04-01

    Semiconducting single-walled carbon nanotubes (s-SWCNTs) are promising candidates as the active layer in photovoltaics (PV), particularly for niche applications where high infrared absorbance and/or semi-transparent solar cells are desirable. Most current fabrication strategies for SWCNT PV devices suffer from relatively high surface roughness and lack nanometer-scale deposition precision, both of which may hamper the reproducible production of ultrathin devices. Additionally, detailed optical models of SWCNT PV devices are lacking, due in part to a lack of well-defined optical constants for high-purity s-SWCNT thin films. Here, we present an optical model that accurately reconstructs the shape and magnitude of spectrally resolved external quantum efficiencies for ultrathin (7,5) s-SWCNT/C60 solar cells that are deposited by ultrasonic spraying. The ultrasonic spraying technique enables thickness tuning of the s-SWCNT layer with nanometer-scale precision, and consistently produces devices with low s-SWCNT film average surface roughness (Rq of <5 nm). Our optical model, based entirely on measured optical constants of each layer within the device stack, enables quantitative predictions of thickness-dependent relative photocurrent contributions of SWCNTs and C60 and enables estimates of the exciton diffusion lengths within each layer. These results establish routes towards rational performance improvements and scalable fabrication processes for ultra-thin SWCNT-based solar cells.Semiconducting single-walled carbon nanotubes (s-SWCNTs) are promising candidates as the active layer in photovoltaics (PV), particularly for niche applications where high infrared absorbance and/or semi-transparent solar cells are desirable. Most current fabrication strategies for SWCNT PV devices suffer from relatively high surface roughness and lack nanometer-scale deposition precision, both of which may hamper the reproducible production of ultrathin devices. Additionally, detailed optical

  12. Homolytic Reactive Mass Spectrometry of Fullerenes: Peculiarities of the Reactions of C60 with Aromatic Compounds in the Ionization Chambers of Mass Spectrometers and in Solution

    NASA Astrophysics Data System (ADS)

    Lyakhovetsky, Yury I.; Shilova, Elena A.; Belokon, Alexander I.; Panz, Larisa I.; Tumanskii, Boris L.

    2013-04-01

    C60 reacted with PhH, PhCl, BnH, BnNH2, and o-C2H2B10H10 in the electron impact (EI) ion source of a mass spectrometer at 300 °C forming phenyl, benzyl, and o-carboranyl adducts, respectively, stabilized by hydrogen addition and loss. Besides, the additions to C60 of methyl and phenyl radicals for toluene, and a phenyl radical for benzylamine were observed. A homolytic reaction mechanism was suggested involving the reaction of the radicals formed from the aromatics under EI with C60 at the ionization chamber walls. While the ion/molecule reaction of C60 with benzene performed by Sun et al. under chemical ionization conditions at 200 °C afforded the complex C60•PhH+•, quite a different isomer, HC60Ph+•, was detected in the present study as a sequence of the different reaction mechanisms. C60 also reacted with benzyl bromide in the laser desorption/ionization (LDI) source of a mass spectrometer to give C60CPh+. Phenyl and benzyl derivatives of C60 were found, respectively, when the reactions of the fullerene with PhCl, BnH, and BnBr were performed in solution under ultra violet irradiation. For the reaction with toluene, the strong chemically induced dynamic electron polarization of the intermediate benzylfullerenyl radical with the reverse phase effect was found. The coincidence of the results of the mass spectrometry and solution reactions of C60 with aromatics, even though incomplete, additionally supports the hypothesis, formulated earlier, that the former results can predict the latter ones to a significant extent and shows that this conclusion is valid for both EI and LDI initiated reactions in mass spectrometers.

  13. Synthesis and structural analysis of C60-C70 two-component fullerene nanowhiskers

    NASA Astrophysics Data System (ADS)

    Konno, Toshio; Wakahara, Takatsugu; Miyazawa, Kun'ichi

    2015-04-01

    C60-C70 two-component fullerene nanowhiskers (C60-C70NWs) were synthesized by liquid-liquid interfacial precipitation (LLIP) using various ratios of C70 to C60 and then analyzed using a focused ion beam processing apparatus (FIB-SEM), scanning electron microscopy (SEM), Raman spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD) and high-performance liquid chromatography (HPLC). Both C60 and C70 were saturated in the supernatant solutions with fullerene compositions in the mother solutions ranging from 12.4 mass% C70 to 73.4 mass% C70. C60-C70NWs contained a small amount of rhombohedral phase, indicating polymerization of C60. The solid solubility limit of C70 in the C60 matrix was found to be 13.7 mass%. In addition to fine C60-C70NWs, thick C60-C70 needle-like crystals were formed. The thick C60-C70 needle-like crystals were fractured using a molybdenum probe in the FIB. The fractured surfaces of the C60-C70 needle-like crystals showed modulated structures with chemical compositions characteristic of spinodal decomposition. The activation energy of diffusion was determined to be 37.1 kJ/mol.

  14. 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.

  15. Structure and absorption in C60-zinc tetra-phenylporphyrin composite materials: A computational study

    NASA Astrophysics Data System (ADS)

    Mitchell, Izaac; Page, Alister J.

    2015-01-01

    We investigate structure and photo-excitation in C60-zinc tetraphenylporphyrin (ZnTPP) and C60F48-ZnTPP complexes, which are promising candidates for organic photovoltaic devices. The C60-ZnTPP complex results from π-π stacking between the fullerene and porphyrin structures, and has a binding energy of 76.0 kJ/mol. Fluorination of the C60 cage leads to decrease in ZnTPP binding, due to reduced π-π stacking interaction. C60-ZnTPP photo-excitation results largely from internal ZnTPP π → π* transitions, although delocalised ZnTPP π → C60 π* transitions are also observed below 300 nm. The more intense photo-excitations of C60F48-ZnTPP arise solely from localised ZnTPP π → π* transitions.

  16. 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+.

  17. Preferable Orientations of Interacting C60 Molecules inside Single Wall Boron Nitride Nanotubes

    NASA Astrophysics Data System (ADS)

    Zhen, Yao; Jia-Yin, Lv; Chun-Jian, Liu; Hang, Lv; Bing-Bing, Liu

    2016-05-01

    Not Available Supported by the National Basic Research Program of China under Grant No 2011CB808200, the National Natural Science Foundation of China under Grant Nos 11504150, 11304020 and 51320105007, and the Cheung Kong Scholars Programme of China.

  18. Measurement of Small Molecular Dopant F4TCNQ and C60F36 Diffusion in Organic Bilayer Architectures.

    PubMed

    Li, Jun; Rochester, Chris W; Jacobs, Ian E; Friedrich, Stephan; Stroeve, Pieter; Riede, Moritz; Moulé, Adam J

    2015-12-30

    The diffusion of molecules through and between organic layers is a serious stability concern in organic electronic devices. In this work, the temperature-dependent diffusion of molecular dopants through small molecule hole transport layers is observed. Specifically we investigate bilayer stacks of small molecules used for hole transport (MeO-TPD) and p-type dopants (F4TCNQ and C60F36) used in hole injection layers for organic light emitting diodes and hole collection electrodes for organic photovoltaics. With the use of absorbance spectroscopy, photoluminescence spectroscopy, neutron reflectometry, and near-edge X-ray absorption fine structure spectroscopy, we are able to obtain a comprehensive picture of the diffusion of fluorinated small molecules through MeO-TPD layers. F4TCNQ spontaneously diffuses into the MeO-TPD material even at room temperature, while C60F36, a much bulkier molecule, is shown to have a substantially higher morphological stability. This study highlights that the differences in size/geometry and thermal properties of small molecular dopants can have a significant impact on their diffusion in organic device architectures. PMID:26673846

  19. 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.

  20. Phenothiazine-bridged cyclic porphyrin dimers as high-affinity hosts for fullerenes and linear array of C60 in self-assembled porphyrin nanotube.

    PubMed

    Sakaguchi, Ken-ichi; Kamimura, Takuya; Uno, Hidemitsu; Mori, Shigeki; Ozako, Shuwa; Nobukuni, Hirofumi; Ishida, Masatoshi; Tani, Fumito

    2014-04-01

    Free-bases and a nickel(II) complex of phenothiazine-bridged cyclic porphyrin dimers bearing self-assembling 4-pyridyl groups (M2-Ptz-CPDPy(OCn); M = H2 or Ni, OCn = OC6 or OC3) at opposite meso-positions have been prepared as host molecules for fullerenes. The free-base dimer (H4-Ptz-CPDPy(OC6)) includes fullerenes with remarkably high association constants such as 3.9 ± 0.7 × 10(6) M(-1) for C60 and 7.4 ± 0.8 × 10(7) M(-1) for C70 in toluene. This C60 affinity is the highest value ever among reported receptors composed of free-base porphyrins. The nickel dimer (Ni2-Ptz-CPDPy(OC6)) also shows high affinities for C60 (1.3 ± 0.2 × 10(6) M(-1)) and C70 (over 10(7) M(-1)). In the crystal structure of the inclusion complex of C60 within H4-Ptz-CPDpy(OC3), the C60 molecule is located just above the centers of the porphyrins. The two porphyrin planes are almost parallel to each other and the center-to-center distance (12.454 Å) is close to the optimal separation (∼12.5 Å) for C60 inclusion. The cyclic porphyrin dimer forms a nanotube through its self-assembly induced by C-H···N hydrogen bonds between porphyrin β-CH groups and pyridyl nitrogens as well as π-π interactions of the pyridyl groups. The C60 molecules are linearly arranged in the inner channel of this nanotube.

  1. 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

  2. The spin chemistry and magnetic resonance of H2@C60. From the Pauli principle to trapping a long lived nuclear excited spin state inside a buckyball.

    PubMed

    Turro, Nicholas J; Chen, Judy Y-C; Sartori, Elena; Ruzzi, Marco; Marti, Angel; Lawler, Ronald; Jockusch, Steffen; López-Gejo, Juan; Komatsu, Koichi; Murata, Yasujiro

    2010-02-16

    One of the early triumphs of quantum mechanics was Heisenberg's prediction, based on the Pauli principle and wave function symmetry arguments, that the simplest molecule, H(2), should exist as two distinct species-allotropes of elemental hydrogen. One allotrope, termed para-H(2) (pH(2)), was predicted to be a lower energy species that could be visualized as rotating like a sphere and possessing antiparallel ( upward arrow downward arrow) nuclear spins; the other allotrope, termed ortho-H(2) (oH(2)), was predicted to be a higher energy state that could be visualized as rotating like a cartwheel and possessing parallel ( upward arrow upward arrow) nuclear spins. This remarkable prediction was confirmed by the early 1930s, and pH(2) and oH(2) were not only separated and characterized but were also found to be stable almost indefinitely in the absence of paramagnetic "spin catalysts", such as molecular oxygen, or traces of paramagnetic impurities, such as metal ions. The two allotropes of elemental hydrogen, pH(2) and oH(2), may be quantitatively incarcerated in C(60) to form endofullerene guest@host complexes, symbolized as pH(2)@C(60) and oH(2)@C(60), respectively. How does the subtle difference in nuclear spin manifest itself when hydrogen allotropes are incarcerated in a buckyball? Can the incarcerated "guests" communicate with the outside world and vice versa? Can a paramagnetic spin catalyst in the outside world cause the interconversion of the allotropes and thereby effect a chemical transformation inside a buckyball? How close are the measurable properties of H(2)@C(60) to those computed for the "quantum particle in a spherical box"? Are there any potential practical applications of this fascinating marriage of the simplest molecule, H(2), with one of the most beautiful of all molecules, C(60)? How can one address such questions theoretically and experimentally? A goal of our studies is to produce an understanding of how the H(2) guest molecules incarcerated in

  3. 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

  4. Dynamic solvation shell and solubility of C60 in organic solvents.

    PubMed

    Wang, Chun I; Hua, Chi C; Chen, Show A

    2014-08-21

    The notion of (static) solvation shells has recently proved fruitful in revealing key molecular factors that dictate the solubility and aggregation properties of fullerene species in polar or ionic solvent media. Using molecular dynamics schemes with carefully evaluated force fields, we have scrutinized both the static and the dynamic features of the solvation shells of single C60 particle for three nonpolar organic solvents (i.e., chloroform, toluene, and chlorobenzene) and a range of system temperatures (i.e., T = 250-330 K). The central findings have been that, while the static structures of the solvation shell remain, in general, insensitive to the effects of changing solvent type or system temperature, the dynamic behavior of solvent molecules within the shell exhibits prominent dependence on both factors. Detailed analyses led us to propose the notion of dynamically stable solvation shell, effectiveness of which can be characterized by a new physical parameter defined as the ratio of two fundamental time constants representing, respectively, the solvent relaxation (or residence) time within the first solvation shell and the characteristic time required for the fullerene particle to diffuse a distance comparable to the shell thickness. We show that, for the five (two from the literature) different solvent media and the range of system temperatures examined herein, this parameter bears a value around unity and, in particular, correlates intimately with known trends of solubility for C60 solutions. We also provide evidence revealing that, in addition to fullerene-solvent interactions, solvent-solvent interactions play an important role, too, in shaping the dynamic solvation shell, as implied by recent experimental trends. PMID:25084556

  5. 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

  6. Interaction of metal porphyrins with fullerene C60: a new insight.

    PubMed

    Liao, Meng-Sheng; Watts, John D; Huang, Ming-Ju

    2007-05-01

    The electronic structure and bonding in the noncovalent, supramolecular complexes of fullerene C60 with a series of first-row transition metal porphines MP (M=Fe, Co, Ni, Cu, Zn) have been re-examined with DFT methods. A dispersion correction was made for the C60-MP binding energy through an empirical method (J. Comput. Chem. 2004, 25, 1463). Several density functionals and two types of basis sets were employed in the calculations. Our calculated results are rather different from those obtained in a recent paper (J. Phys. Chem. A 2005, 109, 3704). The ground state of C60.FeP is predicted to be high spin (S=2); the low-spin (S=0), closed-shell state is even higher in energy than the intermediate-spin (S=1) state. With only one electron in the Co-dz2 orbital, the calculated Co-C60 distance is in fact rather short, about 0.1 A longer than the Fe-C60 distance in high-spin C60.FeP. Double occupation of an M-dz2 orbital in MP prevents close association of any axial ligand, and so the Ni-C60, Cu-C60, and Zn-C60 distances are much longer than the Co-C60 one. The evaluated MP-C60 binding energies (Ebind) are 0.8 eV (18.5 kcal/mol) for M=Fe/Co and 0.5 eV (11.5 kcal/mol) for M=Ni/Cu/Zn (Ebind is about 0.2 eV larger in the case of C60-MTPP). They are believed to be reliable and accurate based on our dispersion-corrected DFT calculations that included the counterpoise (CP) correction. The effects of the C60 contact on the redox properties of MP were also examined.

  7. 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.

  8. Raman spectroscopy measurements of the vibrational properties of uv-polymerized C60 thin film and C60 powder compressed in a diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Li, Y.; Singh, D.; Sharma, S. C.

    2002-03-01

    We present results from a series of experiments designed to further study the effects of pressure on the vibrational properties of C60 compressed under high pressures (10 GPa) in a diamond anvil cell. The Raman scattering measurements were made by using a high resolution optical spectrometer that consists of a 1.25 m, f/11 monochromator, 2400 g/mm, ion-etched blazed holographic diffraction grating, 2048x512 pixel back illuminated liquid nitrogen cooled CCD camera, Super-Notch-Plus filter, argon-ion laser operating at 514.5 nm, and SpectraMax for Windows software. The Raman scattering measurements on C60 thin films show a large ( 10 cm-1) and characteristic red shift in the pentagonal pinch mode Ag(2) of pristine C60 upon irradiation by 21.2 eV photons. Upon heating this film under 10(-3) Torr vacuum at 413 and 473 K, the Raman spectra shift towards the pentagonal pinch mode of pristine C60. These results are in agreement with previously published data (1,2) and they show that the film is polymerized because of uv irradiation. We have also measured spectra for C60 powder compressed under high pressures in a diamond anvil cell. We present results for several frequencies of the Raman active modes of C60. 1. A. M. Rao et al, Science 259, 955 (1993); 2. S. C. Sharma et al, Mat. Res. Symp. Proc. 695, L3.10 (2002)

  9. 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-.

  10. Efficient singlet oxygen generation from sugar pendant C60 derivatives for photodynamic therapy.

    PubMed

    Yano, Shigenobu; Naemura, Masami; Toshimitsu, Akio; Akiyama, Motofusa; Ikeda, Atsushi; Kikuchi, Jun-ichi; Shen, Xiande; Duan, Qian; Narumi, Atsushi; Inoue, Masahiro; Ohkubo, Kei; Fukuzumi, Shunichi

    2015-12-01

    The amidation reaction between C60 with an activated ester group (1) and acetylated Glc (AcGlc) with an amino group (2) was performed to yield the target AcGlc-pendant C60 compound (3). The water soluble deacetylated compound, Glc-pendant C60 compound (4), exhibited high photocytotoxicity against HeLa cells due to the more efficient singlet oxygen generation as compared with that of Glc-pendant azafulleroids. PMID:26420023

  11. 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

  12. 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.

  13. Uncontrolled variability in the extinction spectra of C60 nanoparticle suspensions.

    PubMed

    Chang, Xiaojun; Vikesland, Peter J

    2013-08-01

    To properly investigate the environmental transport, fate, and impact of fullerene C60 nanoparticles (nC60), it is necessary to reproducibly obtain nC60 suspensions and to accurately determine their concentration ([C60]). The results in the present study, however, clearly illustrate that the production of nC60 via extended mixing and via sonication are highly stochastic top-down processes subject to widely divergent end points. nC60 suspensions exhibit variable characteristics (e.g., [C60], average particle size, size distribution, etc.) that make it challenging, if not impossible, to acquire reproducible UV-vis extinction spectra. The mass extinction coefficient, which is the absorptivity of a suspension with [C60] = 1 mM obtained by normalizing UV-vis spectra by the mass concentration of C60 in the suspension, decreases with a given suspension's hydrodynamic diameter, whereas the particle extinction coefficient, which is the absorptivity of a suspension containing one mole of nC60 nanoparticles with the same size distribution as the target suspension and calculated based upon the suspension nanoparticle size distribution, increases with its number weighted average diameter. Other spectroscopic properties of nC60 (e.g., absorbance bandwidth, position of absorption maximum, and relative extinction intensity) also change with average particle size. As a result of the extant variability between samples, when UV-vis spectra are employed to calculate or represent [C60] for fullerene nanoparticle suspensions, extreme care must be taken and other colloidal properties of this suspension must be measured to obtain an accurate result.

  14. 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.

  15. 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.

  16. 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.

  17. First-principles computational studies of alkali-doped C60 fullerides. Final technical report, 1 Jan 91-1 Jan 92

    SciTech Connect

    Erwin, S.C.

    1992-04-06

    Researchers at AT and T Bell Laboratories reported the discovery of superconductivity at 18 K in a potassium-doped fullerene solid, KxC60. This marked a major turning point in the young history of the C60 molecule 'buckminsterfullerene': from a hypothetical molecular (1985), to small-scale (mg) production of crystalline powders (1988), to large-scale synthesis (1990), to a material with the highest transition temperature of any molecular superconductor. This history represents only one of many research lines. Concurrently with the work at AT and T on partial doping, researchers at the Laboratory for Research on the Structure of Matter at the University of Pennsylvania were doping solid C60 to saturation with potassium. The resulting pure phase, K6C60, was characterized by x-ray diffraction in April 1991: the lattice was body-centered cubic, with the C60 molecules essentially undistorted, orientationally ordered, and each surrounded by a cage of 24 K atoms. Nothing was known about the electronic structure at this early stage.

  18. Solvent-free functionalization of fullerene C60 and pristine multi-walled carbon nanotubes with aromatic amines

    NASA Astrophysics Data System (ADS)

    Ramírez-Calera, Itzel J.; Meza-Laguna, Victor; Gromovoy, Taras Yu.; Chávez-Uribe, Ma. Isabel; Basiuk, Vladimir A.; Basiuk, Elena V.

    2015-02-01

    We employed a direct one-step solvent-free covalent functionalization of solid fullerene C60 and pristine multi-walled carbon nanotubes (MWCNTs) with aromatic amines 1-aminopyrene (AP), 2-aminofluorene (AF) and 1,5-diaminonaphthalene (DAN). The reactions were carried out under moderate vacuum, in a wide temperature range of 180-250 °C, during relatively short time of about 2 h. To confirm successful amine attachment, a large number of analytical techniques were used (depending on the nanomaterial functionalized) such as Fourier transform infrared, Raman, X-ray photoelectron, 13C cross-polarization magic angle spinning NMR spectroscopy, thermogravimetric analysis, laser-desorption ionization time-of-flight mass spectrometry, temperature-programmed desorption with mass spectrometric detection, as well as scanning and transmission electron microscopy. The nucleophilic addition of the aromatic amines to C60 molecule was studied theoretically by using density functional theory (PBE GGA functional with Grimme dispersion correction in conjunction with the DNP basis set). In the case of crystalline C60, the solvent-free technique has a limited applicability due to poor diffusion of vaporous aromatic amines into the bulk. Nevertheless, the approach proposed allows for a facile preparation of aromatic amine-functionalized pristine MWCNTs without contamination with other chemical reagents, detergents and solvents, which is especially important for a vast variety of nanotube applications spanning from nanoelectronics to nanomedicine.

  19. 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.

  20. 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

  1. 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.

  2. 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...

  3. 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.

  4. 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.

  5. Synthesis of a Crushed Fullerene C60H24 through Sixfold Palladium‐Catalyzed Arylation

    PubMed Central

    Dorel, Ruth; de Mendoza, Paula; Calleja, Pilar; Pascual, Sergio; González‐Cantalapiedra, Esther; Cabello, Noemí

    2016-01-01

    The synthesis of a new C 3v‐symmetric crushed fullerene C60H24 (5) has been accomplished in three steps from truxene through sixfold palladium‐catalyzed intramolecular arylation of a syn‐trialkylated truxene precursor. Laser irradiation of 5 induces cyclodehydrogenation processes that result in the formation of C60, as detected by LDI‐MS. PMID:27774038

  6. 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...

  7. 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 ...

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. C60 fullerene affects elastic properties and osmoregulation reactions of human lymphocytes.

    PubMed

    Skorkina, Marina Yu; Sladkova, Evgenia A; Shamray, Elena A; Cherkashina, Olga V; Evstigneev, Maxim P; Buchelnikov, Anatoly S; Prylutskyy, Yuriy I; Ritter, Uwe

    2015-09-01

    The influence of aqueous solution of pristine C60 fullerene (C60FAS) on functional activity of lymphocytes from a healthy person was studied for the first time. By means of atomic force microscopy, it was found that C60FAS in a concentration of 0.1 mg/ml increases the stiffness of the lymphocyte membrane by 41% (p < 0.05) and lowers the functional activity of the plasmalemma surface, thereby constraining the use of its membrane material in physiological reactions using a hypotonic model in vitro. However, a cell retains the ability to regulate its volume and demonstrates relative resistance to hypo-osmotic stress. The resistance of lymphocytes in hypo-osmotic medium is facilitated by activation of the nucleus by C60 fullerene particles, which regulates the implementation of two consistent phases of an increase and decrease of cell volume, thereby retaining cell viability. All these indicate the impact of C60 fullerene on the cellular nucleus.

  13. 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.

  14. Interaction of Human Serum Album and C60 Aggregates in Solution

    PubMed Central

    Song, Maoyong; Liu, Shufang; Yin, Junfa; Wang, Hailin

    2011-01-01

    An important property of C60 in aquatic ecotoxicology is that it can form stable aggregates with nanoscale dimensions, namely nC60. Aggregation allows fullerenes to remain suspended for a long time, and the reactivity of individual C60 is substantially altered in this aggregate form. Herein, we investigated the interaction of nC60 and human serum album (HSA) using the methods of fluorescence, fluorescence dynamics, circular dichroism (CD), and site marker competitive experiments. We proposed a binding model consistent with the available experimental results for the interactions of nC60 with HSA. During the interaction process, the structure and conformation of HSA were affected, leading to functional changes of drug binding sites of HSA. PMID:21954338

  15. Ni endohedral-doped C60 with duality of magnetic moments

    NASA Astrophysics Data System (ADS)

    Li, J. L.; Yang, G. W.

    2010-06-01

    We have performed the magnetic properties of Ni endohedral-doped C60 (Ni@C60) by the spin-polarized density functional calculations, and showed that there are three stable configurations depending on different sites of the doped Ni atoms. Due to the high hybridization and confinement effects, the magnetic moment of the Ni-encapsulated metallofullerenes has duality, i.e., altering between 2.02μB and zero, by positioning the Ni atom in the hollow cage of C60. These findings of the alternative magnetic moments of the Ni-encapsulated C60 implied that Ni@C60 could be expected to be promising as a single molecular magnetic switch.

  16. 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

  17. Structure and properties of Li@C60-PF6 endofullerene complex

    NASA Astrophysics Data System (ADS)

    Srivastava, Ambrish Kumar; Kumar, Abhishek; Misra, Neeraj

    2016-10-01

    Li@C60 is a prototype endofullerene, which has been widely studied. Employing density functional theory we study the interaction of Li@C60 with PF6 superhalogen, which leads to the formation of Li@C60-PF6 endofullerene complex. The spectral properties such as infrared and UV-visible spectra have been calculated, which agree well with corresponding experimental data. The vibrational assignments and electronic transitions in the complex have been explored. We have noticed that this complex is stabilized by charge transfer from Li@C60 to PF6, which results in its large dipole moment (20 Debye), high mean polarizability (494 a.u.) and significant mean hyperpolarizability (1500 a.u.). We, therefore, believe that Li@C60-PF6 endofullerene complex might attract further attention for their possible electrooptical applications due to its enhanced nonlinear optical properties.

  18. Sharp organic interface of molecular C60 chains and a pentacene derivative SAM on Au(788): A combined STM & DFT study

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Tang, Jian-Ming; Larson, Amanda M.; Miller, Glen P.; Pohl, Karsten

    2013-12-01

    Controlling the molecular structure of the donor-acceptor interface is essential to overcoming the efficiency bottleneck in organic photovoltaics. We present a study of self-assembled fullerene (C60) molecular chains on perfectly ordered 6,13-dichloropentacene (DCP) monolayers forming on a vicinal Au(788) surface using scanning tunneling microscopy in conjunction with density functional theory calculations. DCP is a novel pentacene derivative optimized for photovoltaic applications. The molecules form a brick-wall patterned centered rectangular lattice with the long axis parallel to the monatomic steps that separate the 3.9 nm wide Au(111) terraces. The strong interaction between the C60 molecules and the gold substrate is well screened by the DCP monolayer. At submonolayer C60 coverage, the fullerene molecules form long parallel chains, 1.1 nm apart, with a rectangular arrangement instead of the expected close-packed configuration along the upper step edges. The perfectly ordered DCP structure is unaffected by the C60 chain formation. The controlled sharp highly-ordered organic interface has the potential to improve the conversion efficiency in organic photovoltaics.

  19. Mixing antisolvents induced modulation in the morphology of crystalline C60.

    PubMed

    Shrestha, Lok Kumar; Hill, Jonathan P; Miyazawa, Kun'ichi; Ariga, Katsuhiko

    2012-08-01

    We present systematic studies of the synthesis of fullerene (C60) crystals with diverse morphologies by liquid-liquid interfacial precipitation (LLIP) method based on different alcohols as antisolvents and aromatic benzene as a solvent. C60 crystals are grown at liquid-liquid interface of mixed isopropyl alcohol (IPA) and tertiary butyl alcohol (TBA) with C60 solution in benzene. The role of mixing IPA and TBA on the morphology of C60 crystal is investigated. One dimensional (1 D) C60 nanowhiskers and polygon-shaped 2D sheets have been grown with individual IPA/benzene and TBA/benzene system, respectively. However, C60 crystals of different morphology (1D, 2D or both), and the self-assembly of nano-sized C60 into micron-sized crystals could be obtained upon mixing IPA and TBA and it is the mixing ratio which determines the morphology. Raman scattering and power X-ray diffraction measurements have shown that these materials are crystalline with cubic and hexagonal structures.

  20. 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.

  1. On the Reaction Mechanism of the Rhodium-Catalyzed Arylation of Fullerene (C60) with Organoboron Compounds in the Presence of Water.

    PubMed

    Martínez, Juan Pablo; Solà, Miquel; Poater, Albert

    2015-12-01

    Density functional theory (DFT) calculations were carried out to study the reaction mechanism of the Suzuki-Miyaura rhodium-catalyzed hydroarylation of fullerene (C60) by phenylboronic acid in the presence of water. As found experimentally, our results confirm that addition of the phenyl group and the hydrogen atom in C60 occurs at the [6,6] bond. The rate-determining step corresponds to the simultaneous transfer of a hydrogen atom from a water molecule to C60 and the recovery of the active species. The use of 2-phenyl-1,3,2-dioxaborinane and the 4,4,5,5-tetramethyl-2-phenyl-1,3,2,-dioxaborolane instead of phenylboronic acid as organoborate agents does not lead to great modifications of the energy profile. The possible higher steric hindrance of 4,4,5,5-tetramethyl-2-phenyl-1,3,2,-dioxaborolane should not inhibit its use in the hydroarylation of C60. Overall, we show how organoboron species arylate C60 in rhodium-based catalysis assisted by water as a source of protons. PMID:27308203

  2. On the Reaction Mechanism of the Rhodium‐Catalyzed Arylation of Fullerene (C60) with Organoboron Compounds in the Presence of Water

    PubMed Central

    Martínez, Juan Pablo; Solà, Miquel

    2015-01-01

    Abstract Density functional theory (DFT) calculations were carried out to study the reaction mechanism of the Suzuki–Miyaura rhodium‐catalyzed hydroarylation of fullerene (C60) by phenylboronic acid in the presence of water. As found experimentally, our results confirm that addition of the phenyl group and the hydrogen atom in C60 occurs at the [6,6] bond. The rate‐determining step corresponds to the simultaneous transfer of a hydrogen atom from a water molecule to C60 and the recovery of the active species. The use of 2‐phenyl‐1,3,2‐dioxaborinane and the 4,4,5,5‐tetramethyl‐2‐phenyl‐1,3,2,‐dioxaborolane instead of phenylboronic acid as organoborate agents does not lead to great modifications of the energy profile. The possible higher steric hindrance of 4,4,5,5‐tetramethyl‐2‐phenyl‐1,3,2,‐dioxaborolane should not inhibit its use in the hydroarylation of C60. Overall, we show how organoboron species arylate C60 in rhodium‐based catalysis assisted by water as a source of protons. PMID:27308203

  3. Bioaccumulation of fullerene (C60) and corresponding catalase elevation in Lumbriculus variegatus.

    PubMed

    Wang, Jiafan; Wages, Mike; Yu, Shuangying; Maul, Jonathan D; Mayer, Greg; Hope-Weeks, Louisa; Cobb, George P

    2014-05-01

    Fullerene (C(60)), with its unique physical properties and nanometer size, has been mass-produced for many applications in recent decades. The increased likelihood of direct release into the environment has raised interest in understanding both the environmental fate and corresponding biological effects of fullerenes to living organisms. Because few studies have emphasized fullerene uptake and resulting biochemical responses by living organisms, a toxicity screening test and a 28-d bioaccumulation test for Lumbriculus variegatus were performed. No mortality was observed in the range of 0.05 mg C(60) /kg dry sediment to 11.33 mg C(60) /kg dry sediment. A biota-sediment accumulation factor of micron-sized fullerene agglomerates (µ-C(60)) was 0.032 ± 0.008 at day 28, which is relatively low compared with pyrene (1.62 ± 0.22). Catalase (CAT) activity, an oxidative stress indicator, was elevated significantly on day 14 for L. variegatus exposed to µ-C(60) (p = 0.034). This peak CAT activity corresponded to the highest body residues observed in the present study, 199 ± 80 µg C(60) /kg dry weight sediment. Additionally, smaller C(60) agglomerate size increased bioaccumulation potential in L. variegatus. The relationship between C(60) body residue and the increased CAT activity followed a linear regression. All results suggest that C(60) has a lower bioaccumulation potential than pyrene but a higher potential to induce oxidative stress in L. variegatus.

  4. Removal of aqueous nC60 fullerene from water by low pressure membrane filtration.

    PubMed

    Floris, R; Nijmeijer, K; Cornelissen, E R

    2016-03-15

    The potential environmental and health risks of engineered nanoparticles such as buckminsterfullerene C60 in water require their removal during the production of drinking water. We present a study focusing on (i) the removal mechanism and (ii) the elucidation of the role of the membrane pore size during removal of nC60 fullerene nanoparticle suspensions in dead-end microfiltration and ultrafiltration mimicking separation in real industrial water treatment plants. Membranes were selected with pore sizes ranging from 18 nm to 500 nm to determine the significance of the nC60 to membrane pore size ratio and the adsorption affinity between nC60 and membrane material during filtration. Experiments were carried out with a dead-end bench-scale system operated at constant flux conditions including a hydraulic backwash cleaning procedure. nC60 nanoparticles can be efficiently removed by low pressure membrane technology with smaller and, unexpectedly, also by mostly similar or larger pores than the particle size, although the nC60 filtration behaviour appeared to be different. The nC60 size to membrane pore size ratio and the ratio of the cake-layer deposition resistance to the clean membrane resistance, both play an important role on the nC60 filtration behaviour and on the efficiency of the backwash procedure recovering the initial membrane filtration conditions. These results become specifically significant in the context of drinking water production, for which they provide relevant information for an accurate selection between membrane processes and operational parameters for the removal of nC60 in the drinking water treatment.

  5. Removal of aqueous nC60 fullerene from water by low pressure membrane filtration.

    PubMed

    Floris, R; Nijmeijer, K; Cornelissen, E R

    2016-03-15

    The potential environmental and health risks of engineered nanoparticles such as buckminsterfullerene C60 in water require their removal during the production of drinking water. We present a study focusing on (i) the removal mechanism and (ii) the elucidation of the role of the membrane pore size during removal of nC60 fullerene nanoparticle suspensions in dead-end microfiltration and ultrafiltration mimicking separation in real industrial water treatment plants. Membranes were selected with pore sizes ranging from 18 nm to 500 nm to determine the significance of the nC60 to membrane pore size ratio and the adsorption affinity between nC60 and membrane material during filtration. Experiments were carried out with a dead-end bench-scale system operated at constant flux conditions including a hydraulic backwash cleaning procedure. nC60 nanoparticles can be efficiently removed by low pressure membrane technology with smaller and, unexpectedly, also by mostly similar or larger pores than the particle size, although the nC60 filtration behaviour appeared to be different. The nC60 size to membrane pore size ratio and the ratio of the cake-layer deposition resistance to the clean membrane resistance, both play an important role on the nC60 filtration behaviour and on the efficiency of the backwash procedure recovering the initial membrane filtration conditions. These results become specifically significant in the context of drinking water production, for which they provide relevant information for an accurate selection between membrane processes and operational parameters for the removal of nC60 in the drinking water treatment. PMID:26773485

  6. Orientational glassification in fullerite C60 saturated with H2: Photoluminescence studies

    NASA Astrophysics Data System (ADS)

    Zinoviev, P. V.; Zoryansky, V. N.; Silaeva, N. B.; Stetsenko, Yu. E.; Strzhemechny, M. A.; Yagotintsev, K. A.

    2012-08-01

    Using one-photon excitation we studied photoluminescence of C60 saturated with molecular hydrogen over a temperature range from 10 to 230 K. Saturation of samples was done at 30 atm and at temperatures low enough (T < 250 °C) to exclude chemical sorption. The samples were saturated during periods of varied duration τ to reach different occupancy levels. To check the reliability of our luminescence results and their interpretation, our spectra for pure C60 were compared with data known in the art, demonstrating good compatibility. The luminescence spectra were attributed according to the approach of Akimoto and Kan'no by separating the total spectra into two components of different origin. The A-type spectra, associated with exciton transport to deep traps, become prevalent over the B-type emission above 70 K. The integrated intensity I as a function of the temperature T of the luminescence measurements I(T) remained at a constant level up to the orientational vitrification point of about 100 K when the saturation times exceeded a certain value (for one, 50 h for a saturation temperature of 200 °C); then I(T) went down rather steeply with increasing T. However, at longer τ the intensity I(Τ) persisted consistently to higher T (the higher, the longer τ) and then dropped with increasing T. This finding made us reexamine the lattice parameter vs. saturation time dependence for saturation temperatures of 200 and 230 °C. As a result, additional evidence allowed us to infer that after the completion of the single-molecule filling of O-voids (specifically, after roughly 50 h at Tsat = 200 °C) a slower process of double filling sets in. Double filling entails an anisotropic deformation of the octahedral cage, which modifies rotational dynamics more than single filling. Further, we argue that singlet exciton transport to traps (which is responsible for the A-type emission) can be crucially hampered by rotational jumps of one of the molecules, over which a travelling

  7. Structural and magnetic properties of Tcn@C60 endohedral metallofullerenes: An ab initio study

    NASA Astrophysics Data System (ADS)

    Kim, Eunja; Weck, Philippe F.; Czerwinski, Kenneth R.; Tománek, David

    2010-03-01

    We use ab initio spin density functional calculations to study the equilibrium structure and magnetic properties of Tcn@C60 endohedral metallofullerenes. The radionuclide ^99mTc is well established in biomedicine as a potent in vivo diagnostic radiopharmaceutical; its encapsulation in the inert C60 shell is expected to limit possible cytotoxicity of radiometal nanoparticles catabolized by the biological host. We find that C60 can endohedrally accommodate Tcn clusters with up to n=7. The encapsulation does not change significantly the structure of the enclosed clusters, but reduces the magnetic moment due to a stronger Tc--C hybridization for the larger clusters.

  8. Antiferromagnetic resonance in the Mott insulator fcc-Cs3C60.

    PubMed

    Suzuki, Yuta; Shibasaki, Seiji; Kubozono, Yoshihiro; Kambe, Takashi

    2013-09-11

    The magnetic ground state of the fcc phase of the Mott insulator Cs3C60 was studied using a low-temperature electron spin resonance technique, and antiferromagnetic resonance (AFMR) below 1.57 K was directly observed at ambient pressure. The AFMR modes for the fcc phase of Cs3C60 were investigated using a conventional two-sublattice model with uniaxial anisotropy, and the spin-flop field was determined to be 4.7 kOe at 1.57 K. The static magnetic exchange interactions and anisotropy field for fcc-Cs3C60 were also estimated.

  9. 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

  10. Spectromicroscopy of C60 and azafullerene C59N: Identifying surface adsorbed water

    NASA Astrophysics Data System (ADS)

    Erbahar, Dogan; Susi, Toma; Rocquefelte, Xavier; Bittencourt, Carla; Scardamaglia, Mattia; Blaha, Peter; Guttmann, Peter; Rotas, Georgios; Tagmatarchis, Nikos; Zhu, Xiaohui; Hitchcock, Adam P.; Ewels, Chris P.

    2016-10-01

    C60 fullerene crystals may serve as important catalysts for interstellar organic chemistry. To explore this possibility, the electronic structures of free-standing powders of C60 and (C59N)2 azafullerenes are characterized using X-ray microscopy with near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy, closely coupled with density functional theory (DFT) calculations. This is supported with X-ray photoelectron spectroscopy (XPS) measurements and associated core-level shift DFT calculations. We compare the oxygen 1s spectra from oxygen impurities in C60 and C59N, and calculate a range of possible oxidized and hydroxylated structures and associated formation barriers. These results allow us to propose a model for the oxygen present in these samples, notably the importance of water surface adsorption and possible ice formation. Water adsorption on C60 crystal surfaces may prove important for astrobiological studies of interstellar amino acid formation.

  11. 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.

  12. Evaluation of C60 secondary ion mass spectrometry for the chemical analysis and imaging of fingerprints.

    PubMed

    Sisco, Edward; Demoranville, Leonard T; Gillen, Greg

    2013-09-10

    The feasibility of using C60(+) cluster primary ion bombardment secondary ion mass spectrometry (C60(+) SIMS) for the analysis of the chemical composition of fingerprints is evaluated. It was found that C60(+) SIMS could be used to detect and image the spatial localization of a number of sebaceous and eccrine components in fingerprints. These analyses were also found to not be hindered by the use of common latent print powder development techniques. Finally, the ability to monitor the depth distribution of fingerprint constituents was found to be possible - a capability which has not been shown using other chemical imaging techniques. This paper illustrates a number of strengths and potential weaknesses of C60(+) SIMS as an additional or complimentary technique for the chemical analysis of fingerprints.

  13. Different hydroxyl radical scavenging activity of water-soluble beta-alanine C60 adducts.

    PubMed

    Sun, Tao; Jia, Zhishen; Xu, Zhude

    2004-04-01

    Three C(60) derivatives [C(60) (NHCH(2)CH(2)COONa)(n)(H)(n)], n=1, 5, 9] (A, B, C) with different additional number of beta-alanine were synthesized by the control of relative amount of C(60) and beta-alanine added. Hydroxyl radical scavenging activity of the adducts was evaluated in a copper-catalyzed Haber-Weiss reaction by chemiluminescence technology. The 50% inhibition concentrations (IC(50)'s) of A, B, and C were 147.2 micromol/L, 76.3 micromol/L, and 96.2 micromol/L, respectively. The difference should be closely related to the numbers of residual C=C bonds in C(60), steric effect and electron-withstanding effect of amino group especially.

  14. 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.

  15. 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

  16. 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.

  17. Polyethylene terephthalate (PET) bulk film analysis using C 60+, Au 3+, and Au + primary ion beams

    NASA Astrophysics Data System (ADS)

    Conlan, X. A.; Gilmore, I. S.; Henderson, A.; Lockyer, N. P.; Vickerman, J. C.

    2006-07-01

    The damage characteristics of polyethylene terephthalate (PET) have been studied under bombardment by C 60+, Au 3+ and Au + primary ions. The observed damage cross-sections for the three ion beams are not dramatically different. The secondary ion yields however were significantly enhanced by the polyatomic primary ions where the secondary ion yield of the [M + H] + is on average 5× higher for C 60+ than Au 3+ and 8× higher for Au 3+ than Au +. Damage accumulates under Au + and Au 3+ bombardment while C 60+ bombardment shows a lack of damage accumulation throughout the depth profile of the PET thick film up to an ion dose of ˜1 × 10 15 ions cm -2. These properties of C 60+ bombardment suggest that the primary ion will be a useful molecular depth profiling tool.

  18. Spectromicroscopy of C60 and azafullerene C59N: Identifying surface adsorbed water

    PubMed Central

    Erbahar, Dogan; Susi, Toma; Rocquefelte, Xavier; Bittencourt, Carla; Scardamaglia, Mattia; Blaha, Peter; Guttmann, Peter; Rotas, Georgios; Tagmatarchis, Nikos; Zhu, Xiaohui; Hitchcock, Adam P.; Ewels, Chris P.

    2016-01-01

    C60 fullerene crystals may serve as important catalysts for interstellar organic chemistry. To explore this possibility, the electronic structures of free-standing powders of C60 and (C59N)2 azafullerenes are characterized using X-ray microscopy with near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy, closely coupled with density functional theory (DFT) calculations. This is supported with X-ray photoelectron spectroscopy (XPS) measurements and associated core-level shift DFT calculations. We compare the oxygen 1s spectra from oxygen impurities in C60 and C59N, and calculate a range of possible oxidized and hydroxylated structures and associated formation barriers. These results allow us to propose a model for the oxygen present in these samples, notably the importance of water surface adsorption and possible ice formation. Water adsorption on C60 crystal surfaces may prove important for astrobiological studies of interstellar amino acid formation. PMID:27748425

  19. Detailed low-energy electron diffraction analysis of the (4×4) surface structure of C60 on Cu(111): Seven-atom-vacancy reconstruction

    NASA Astrophysics Data System (ADS)

    Xu, Geng; Shi, Xing-Qiang; Zhang, R. Q.; Pai, Woei Wu; Jeng, H. T.; Van Hove, M. A.

    2012-08-01

    A detailed and exhaustive structural analysis by low-energy electron diffraction (LEED) is reported for the C60-induced reconstruction of Cu(111), in the system Cu(111) + (4 × 4)-C60. A wide LEED energy range allows enhanced sensitivity to the crucial C60-metal interface that is buried below the 7-Å-thick molecular layer. The analysis clearly favors a seven-Cu-atom vacancy model (with Pendry R-factor Rp = 0.376) over a one-Cu-atom vacancy model (Rp = 0.608) and over nonreconstructed models (Rp = 0.671 for atop site and Rp = 0.536 for hcp site). The seven-Cu-atom vacancy forms a (4 × 4) lattice of bowl-like holes. In each hole, a C60 molecule can nestle by forming strong bonds (shorter than 2.30 Å) between 15 C atoms of the molecule and 12 Cu atoms of the outermost and second Cu layers.

  20. Influence of CO molecular impurity on the structural and thermodynamic properties of fullerite C60, in a broad range of sorption temperatures

    NASA Astrophysics Data System (ADS)

    Meleshko, V. V.; Legchenkova, I. V.; Stetsenko, Y. E.; Prokhvatilov, A. I.

    2016-02-01

    An x-ray diffraction study of how sorption of CO gas at a pressure of 30 atm in the temperature range of 150-600 °C influences the structural characteristics of polycrystalline and single crystal fullerite C60. The sorption kinetics are studied by constructing a dependence of the lattice parameter on the time it takes for fullerite to be saturated by CO molecules. At temperatures Tsorb > 300 °C there is an observed dissociation of carbon monoxide, accompanied by the precipitation of carbon powder and the chemical interaction of atomic oxygen with C60 and CO molecules, and possibly with the carbon condensate. These processes have a strong influence on the structural characteristics of fullerite, thus creating, in part, a nonmonotonic dependence of the parameter and lattice matrix volume on the impurity saturation temperature. The concentrations of solid solutions C60(CO)x poly- and single crystal samples are determined in the physisorption range for two modes (150 and 250 °C). It is found that the CO impurity has a linear effect on the lattice parameter and the temperature of the orientational transition of fullerite C60.

  1. Ground State Reactions of nC60 with Free Chlorine in Water.

    PubMed

    Wu, Jiewei; Benoit, Denise; Lee, Seung Soo; Li, Wenlu; Fortner, John D

    2016-01-19

    Facile, photoenhanced transformations of water-stable C60 aggregates (nC60) to oxidized, soluble fullerene derivatives, have been described as key processes in understanding the ultimate environmental fate of fullerene based materials. In contrast, fewer studies have evaluated the aqueous reactivity of nC60 during ground-state conditions (i.e., dark conditions). Herein, this study identifies and characterizes the physicochemical transformations of C60 (as nC60 suspensions) in the presence of free chlorine, a globally used chemical oxidant, in the absence of light under environmentally relevant conditions. Results show that nC60 undergoes significant oxidation in the presence of free chlorine and the oxidation reaction rates increase with free chlorine concentration while being inversely related to solution pH. Product characterization by FTIR, XPS, Raman Spectroscopy, TEM, XRD, TOC, collectively demonstrates that oxidized C60 derivatives are readily formed in the presence of free chlorine with extensive covalent oxygen and even chlorine additions, and behave as soft (or loose) clusters in solution. Aggregation kinetics, as a function of pH and ionic strength/type, show a significant increase in product stabilities for all cases evaluated, even at pH values approaching 1. As expected with increased (surface) oxidation, classic Kow partitioning studies indicate that product clusters are relatively more hydrophilic than parent (reactant) nC60. Taken together, this work highlights the importance of understanding nanomaterial reactivity and the identification of corresponding stable daughter products, which are likely to differ significantly from parent material properties and behaviors. PMID:26651395

  2. 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.

  3. Self-assembling hybrid nanoparticles during simultaneous deposition of Co and C60 on sapphire.

    PubMed

    Lavrentiev, Vasily; Vacik, Jiri; Naramoto, Hiroshi; Sakai, Seiji

    2009-07-01

    The Co-C60 nano-composite film prepared by simultaneous deposition of Co and C60 at room temperature (RT) on sapphire with high content of cobalt (50 at.% Co) is recognized as ensemble of the fcc-Co crystals (5-6 nm in size) separated by the C60-based matrix. It is shown formation of internal stress in the composition arising due to the phase separation. The internal stress causes the phenomena sufficiently influencing structure of the nano-composite. One of them is locking the Co atoms within the C60-based matrix (retained Co atoms) occurring during the separation process. Analysis of the Raman spectrum argues that the retained Co atoms are included in the Co-C60 polymer dominating in the matrix of nano-composite. It is suggested importance of the internal stress for the polymer formation. Another phenomenon is the structural relaxation releasing the internal stress. These phenomena are tested through applying different thermal treatments. Raman spectrum of the mixture film deposited at 200 degrees C shows the lower polymerization efficiency in the C60-based matrix due to the more complete phase separation decreasing number of the retained Co atoms. Post-deposition annealing of the RT-deposited Co-C60 mixture film done at 300 degrees C for 1 hour induces the structural relaxation as conversion of fullerene into the regular carbon structure. According to the Raman analysis the regular carbon structure corresponds to the single-wall carbon nanotubes (SWNT) doped by cobalt. Similar analysis of the 200 degrees C-deposited mixture film treated by the following annealing reveals formation of SWNT only after much longer annealing. These experiments designate the Co diffusion as a main process driven by the carbon nanotube formation. The results demonstrate remarkable opportunity to control structure of the Co-C60 nano-composite using proper thermal treatments.

  4. Ground State Reactions of nC60 with Free Chlorine in Water.

    PubMed

    Wu, Jiewei; Benoit, Denise; Lee, Seung Soo; Li, Wenlu; Fortner, John D

    2016-01-19

    Facile, photoenhanced transformations of water-stable C60 aggregates (nC60) to oxidized, soluble fullerene derivatives, have been described as key processes in understanding the ultimate environmental fate of fullerene based materials. In contrast, fewer studies have evaluated the aqueous reactivity of nC60 during ground-state conditions (i.e., dark conditions). Herein, this study identifies and characterizes the physicochemical transformations of C60 (as nC60 suspensions) in the presence of free chlorine, a globally used chemical oxidant, in the absence of light under environmentally relevant conditions. Results show that nC60 undergoes significant oxidation in the presence of free chlorine and the oxidation reaction rates increase with free chlorine concentration while being inversely related to solution pH. Product characterization by FTIR, XPS, Raman Spectroscopy, TEM, XRD, TOC, collectively demonstrates that oxidized C60 derivatives are readily formed in the presence of free chlorine with extensive covalent oxygen and even chlorine additions, and behave as soft (or loose) clusters in solution. Aggregation kinetics, as a function of pH and ionic strength/type, show a significant increase in product stabilities for all cases evaluated, even at pH values approaching 1. As expected with increased (surface) oxidation, classic Kow partitioning studies indicate that product clusters are relatively more hydrophilic than parent (reactant) nC60. Taken together, this work highlights the importance of understanding nanomaterial reactivity and the identification of corresponding stable daughter products, which are likely to differ significantly from parent material properties and behaviors.

  5. 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.

  6. 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

  7. 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.

  8. Effects of light energy and reducing agents on C60-mediated photosensitizing reactions.

    PubMed

    Quinones, Michael; Zhang, Yazhou; Riascos, Penelope; Hwang, Huey-Min; Aker, Winfred G; He, Xiaojia; Gao, Ruomei

    2014-01-01

    Many biomolecules contain photoactive reducing agents, such as reduced nicotinamide adenine dinucleotide (NADH) and 6-thioguanine (6-TG) incorporated into DNA through drug metabolism. These reducing agents may produce reactive oxygen species under UVA irradiation or act as electron donors in various media. The interactions of C60 fullerenes with biological reductants and light energy, especially via the Type-I electron-transfer mechanism, are not fully understood although these factors are often involved in toxicity assessments. The two reductants employed in this work were NADH for aqueous solutions and 6-TG for organic solvents. Using steady-state photolysis and electrochemical techniques, we showed that under visible light irradiation, the presence of reducing agents enhanced C60 -mediated Type-I reactions that generate superoxide anion (O2(.-)) at the expense of singlet oxygen ((1)O2) production. The quantum yield of O2(.-) production upon visible light irradiation of C60 is estimated below 0.2 in dipolar aprotic media, indicating that the majority of triplet C60 deactivate via Type-II pathway. Upon UVA irradiation, however, both C60 and NADH undergo photochemical reactions to produce O2(.-), which could lead to a possible synergistic toxicity effects. C60 photosensitization via Type-I pathway is not observed in the absence of reducing agents.

  9. 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.

  10. 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.

  11. Potential Suppressive Effects of Two C60 Fullerene Derivatives on Acquired Immunity

    NASA Astrophysics Data System (ADS)

    Hirai, Toshiro; Yoshioka, Yasuo; Udaka, Asako; Uemura, Eiichiro; Ohe, Tomoyuki; Aoshima, Hisae; Gao, Jian-Qing; Kokubo, Ken; Oshima, Takumi; Nagano, Kazuya; Higashisaka, Kazuma; Mashino, Tadahiko; Tsutsumi, Yasuo

    2016-10-01

    The therapeutic effects of fullerene derivatives on many models of inflammatory disease have been demonstrated. The anti-inflammatory mechanisms of these nanoparticles remain to be elucidated, though their beneficial roles in allergy and autoimmune diseases suggest their suppressive potential in acquired immunity. Here, we evaluated the effects of C60 pyrrolidine tris-acid (C60-P) and polyhydroxylated fullerene (C60(OH)36) on the acquired immune response in vitro and in vivo. In vitro, both C60 derivatives had dose-dependent suppressive effects on T cell receptor-mediated activation of T cells and antibody production by B cells under anti-CD40/IL-4 stimulation, similar to the actions of the antioxidant N-acetylcysteine. In addition, C60-P suppressed ovalbumin-specific antibody production and ovalbumin-specific T cell responses in vivo, although T cell-independent antibodies responses were not affected by C60-P. Together, our data suggest that fullerene derivatives can suppress acquired immune responses that require T cells.

  12. 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.

  13. Differential photoactivity of aqueous [C60] and [C70] fullerene aggregates.

    PubMed

    Moor, Kyle J; Snow, Samuel D; Kim, Jae-Hong

    2015-05-19

    Many past studies have focused on the aqueous photochemical properties of colloidal suspensions of C60 and various [C60] fullerene derivatives, yet few have investigated the photochemistry of other larger cage fullerene species (e.g., C70, C74, C84, etc.) in water. This is a critical knowledge gap because these larger fullerenes may exhibit different properties compared to C60, including increased visible light absorption, altered energy level structures, and variable cage geometries, which may greatly affect aggregate properties and resulting aqueous photoactivity. Herein, we take the first steps toward a detailed investigation of the aqueous photochemistry of larger cage fullerene species, by focusing on [C70] fullerene. We find that aqueous suspensions of C60 and C70, nC60 and nC70, respectively, exhibit many similar physicochemical properties, yet nC70 appears to be significantly more photoactive than nC60. Studies are conducted to elucidate the mechanism behind nC70's superior (1)O2 generation, including the measurement of (1)O2 production as a function of incident excitation wavelength, analysis of X-ray diffraction data to determine crystal packing arrangements, and the excited state dynamics of aggregate fullerene species via transient absorption spectroscopy.

  14. 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

  15. 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.

  16. New approach for sensitive photothermal detection of C60 and C70 fullerenes on micro-thin-layer chromatographic plates.

    PubMed

    Suszyński, Zbigniew; Zarzycki, Paweł K

    2015-03-10

    In this paper the pulse thermovision (photothermal) detection and quantification methods of C60 and C70 fullerenes are presented. Quantification results are compared with optical and fluorescence measurements. Target components were separated under isothermal conditions (30 °C) on micro-TLC plates (RP18WF254S) using n-hexane as the mobile phase. The principle of described analytical protocol is based on sensitive measurement of the temperature contrast generated within TLC stationary phase and fullerenes spots after white light pulse excitation. It has been demonstrated that observed temperature contrast is mainly driven by the optical properties of fullerenes (UV-vis absorption spectra). Contrary to the commonly applied optical reflection or transmission techniques the proposed thermovision method involves dissipated light. The results of presented experimental work have revealed that both types of quantitative measurements provide similar outcome despite the key differences in the signal origin. However, it has been found that thermovision method was characterized by smaller value of LOD, particularly for C60 molecule. We demonstrated that application of correlation technique to post-acquisition analysis of the sequence of temperature contrast images significantly increase detection limits of fullerenes, even in comparison to fluorescence quenching detection mode. Moreover, the thermal contrast images and particularly, computed correlation image, allow detection of stationary phase layer nonuniformities, including changes in the adsorbent thickness and thermal conductivity. Therefore, invented pulsed thermovision methodology can be additionally used for fast quality screening of home made and commercially available TLC plates.

  17. Ab-inito calculation of energy level alignment and vacuum level shift at CuPc/C60 interfaces

    NASA Astrophysics Data System (ADS)

    Sai, Na; Zhu, Xiaoyang; Chelikowsky, James; Leung, Kevin

    2012-02-01

    The alignment of the donor and acceptor enegy levels is of crucial importance for organic photovotaic performance. We investigate the interfaical electronic structure and energy level alignment of copper phthalocyanine (CuPc)/fullerene (C60) using ab-inito density functional theory calculations including van der Waals interactions and hybrid density functionals. We show that energy level alignment critically depends on the standing-up and lying-down orientation of the CuPc molecules relative to C60 at the interface. We calculate the magnitude of the interface dipole at different molecular orientations and compare them to the vacuum level shift observed in photoemission spectroscopy. The validity of existing theoretical models which invoke charge transfer on this organic interface will be discussed in light of our predictions. Sandia National Laboratories is a multiprogram laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Deparment of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  18. First Production of C60 Nanoparticle Plasma Jet for Study of Disruption Mitigation for ITER

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    Unique fast response and large mass-velocity delivery of nanoparticle plasma jets (NPPJs) provide a novel application for ITER disruption mitigation, runaway electrons diagnostics and deep fueling. NPPJs carry a much larger mass than usual gases. An electromagnetic plasma gun provides a very high injection velocity (many km/s). NPPJ has much higher ram pressure than any standard gas injection method and penetrates the tokamak confining magnetic field. Assimilation is enhanced due to the NP large surface-to-volume ratio. Radially expanding NPPJs help achieving toroidal uniformity of radiation power. FAR-TECH's NPPJ system was successfully tested: a coaxial plasma gun prototype (˜35 cm length, 96 kJ energy) using a solid state TiH2/C60 pulsed power cartridge injector produced a hyper-velocity (>4 km/s), high-density (>10^23 m-3), C60 plasma jet in ˜0.5 ms, with ˜1-2 ms overall response-delivery time. We present the TiH2/C60 cartridge injector output characterization (˜180 mg of sublimated C60 gas) and first production results of a high momentum C60 plasma jet (˜0.6 g.km/s).

  19. Structural relaxation of adlayers in the presence of adsorbate-induced reconstruction: C60/Cu(111)

    NASA Astrophysics Data System (ADS)

    Pai, Woei Wu; Hsu, Ching-Ling; Lin, M. C.; Lin, K. C.; Tang, T. B.

    2004-03-01

    We revisit submonolayer growth of C60 on Cu(111) by scanning tunneling microscopy (STM), with emphasis on the formation of higher-order commensurate metastable states. These phases show concomitant interfacial reconstruction, adlayer buckling, and adlayer rotation in order to match as closely as possible the 10.0 Å C60 nearest neighbor (NN) distance. Most interestingly, a clear correlation between the adlayer rotation angle and molecular contrast patterns is demonstrated. This is caused by the C60-induced reconstruction at preferred binding sites and adlayer buckling in adjustment to strain. Four contrast patterns, i.e., “disordered maze,” “linear-wall maze,” “p(√(7)×√(7)),” and “p(2×2),” with increasing C60 NN distances are categorized. In the most compressed phase, buckling is favored and it is analogous to the ground state of a strongly-coupled antiferromagnetic system on a triangular lattice with alike adlayer buckling and interfacial corrugation. In contrast, the molecular orderings in the other structures are mostly dictated by lateral displacements of C60 toward preferred reconstructive binding sites. These metastable phases thus illustrate structural relaxation of a molecular layer on an adsorbate-induced reconstructed substrate in different adsorbate-adsorbate and adsorbate-substrate interaction limits.

  20. Structural relaxation of an adlayer in presence of adsorbate-induced reconstruction: C_60/Cu(111)

    NASA Astrophysics Data System (ADS)

    Pai, Woei Wu; Hsu, C. L.; Lin, M. C.; Lin, K. C.

    2004-03-01

    We revisit submonolayer growth of C_60 on Cu(111) by STM, with emphasis on the formation of higher-order commensurate metastable states. These phases show concomitant interfacial reconstruction, adlayer buckling, and adlayer rotation to match to the 10.0 ÅC_60 nearest neighbor (NN) distance. Most interestingly, a clear correlation between the adlayer rotation angle and molecular contrast patterns is demonstrated. This is caused by the C_60-induced reconstruction at preferred binding sites and adlayer buckling in adjustment to strain. Four contrast patterns, i.e., ''disordered-maze'', ''linear-wall-maze'', ''p(√7 × √7)'', and ''p (2 × 2)'', with increasing C_60 NN distances are categorized. In the most compressed phase, buckling is favored and it is analogous to the ground state of an antiferromagnetic system on a triangular lattice with alike adlayer buckling and interfacial corrugation. In contrast, the molecular orderings in the other structures are mostly dictated by lateral displacements of C_60 toward preferred reconstructive binding sites. These phases thus illustrate structural relaxation of a molecular layer on an adsobate-induced reconstructed substrate in different adsorbate-adsorbate and adsorbate-substrate interaction limits.

  1. nC60 deposition kinetics: the complex contribution of humic acid, ion concentration, and valence.

    PubMed

    McNew, Coy P; LeBoeuf, Eugene J

    2016-07-01

    The demonstrated toxicity coupled with inevitable environmental release of nC60 raise serious concerns about its environmental fate and transport, therefore it is crucial to understand how nC60 will interact with subsurface materials including attached phase soil and sediment organic matter (AP-SOM). This study investigated the attachment of nC60 onto a Harpeth humic acid (HHA) coated silica surface under various solution conditions using a quartz crystal microbalance with dissipation monitoring. The HHA coating greatly enhanced nC60 attachment at low ion concentrations while hindering attachment at high ion concentrations in the presence of both mono and divalent cations. At low ion concentrations, the HHA greatly reduced the surface potential of the silica, enhancing nC60 deposition through reduction in the electrostatic repulsion. At high ion concentrations however, the reduced surface potential became less important due to the near zero energy barrier to deposition and therefore non-DLVO forces dominated, induced by compaction of the HHA layer, and leading to hindered attachment. In this manner, observed contributions from the HHA layer were more complex than previously reported and by monitoring surface charge and calculated DLVO interaction energy alongside attachment experiments, this study advances the mechanistic understanding of the variable attachment contributions from the humic acid layer.

  2. nC60 deposition kinetics: the complex contribution of humic acid, ion concentration, and valence.

    PubMed

    McNew, Coy P; LeBoeuf, Eugene J

    2016-07-01

    The demonstrated toxicity coupled with inevitable environmental release of nC60 raise serious concerns about its environmental fate and transport, therefore it is crucial to understand how nC60 will interact with subsurface materials including attached phase soil and sediment organic matter (AP-SOM). This study investigated the attachment of nC60 onto a Harpeth humic acid (HHA) coated silica surface under various solution conditions using a quartz crystal microbalance with dissipation monitoring. The HHA coating greatly enhanced nC60 attachment at low ion concentrations while hindering attachment at high ion concentrations in the presence of both mono and divalent cations. At low ion concentrations, the HHA greatly reduced the surface potential of the silica, enhancing nC60 deposition through reduction in the electrostatic repulsion. At high ion concentrations however, the reduced surface potential became less important due to the near zero energy barrier to deposition and therefore non-DLVO forces dominated, induced by compaction of the HHA layer, and leading to hindered attachment. In this manner, observed contributions from the HHA layer were more complex than previously reported and by monitoring surface charge and calculated DLVO interaction energy alongside attachment experiments, this study advances the mechanistic understanding of the variable attachment contributions from the humic acid layer. PMID:27061365

  3. The interaction of C60 on Si(111) 7x7 studied by Supersonic Molecular Beams: interplay between precursor kinetic energy and substrate temperature in surface activated processes.

    NASA Astrophysics Data System (ADS)

    Aversa, Lucrezia; Taioli, Simone; Nardi, Marco; Tatti, Roberta; Verucchi, Roberto; Iannotta, Salvatore

    2015-06-01

    Buckminsterfullerene (C60) is a molecule fully formed of carbon that can be used, owing to its electronic and mechanical properties, as “clean” precursor for the growth of carbon-based materials, ranging from ?-conjugated systems (graphenes) to synthesized species, e.g. carbides such as silicon carbide (SiC). To this goal, C60 cage rupture is the main physical process that triggers material growth. Cage breaking can be obtained either thermally by heating up the substrate to high temperatures (630°C), after C60 physisorption, or kinetically by using Supersonic Molecular Beam Epitaxy (SuMBE) techniques. In this work, aiming at demonstrating the growth of SiC thin films by C60 supersonic beams, we present the experimental investigation of C60 impacts on Si(111) 7x7 kept at 500°C for translational kinetic energies ranging from 18 to 30 eV. The attained kinetically activated synthesis of SiC submonolayer films is probed by in-situ surface electron spectroscopies (XPS and UPS). Furthermore, in these experimental conditions the C60-Si(111) 7×7 collision has been studied by computer simulations based on a tight-binding approximation to Density Functional Theory, DFT. Our theoretical and experimental findings point towards a kinetically driven growth of SiC on Si, where C60 precursor kinetic energy plays a crucial role, while temperature is relevant only after cage rupture to enhance Si and carbon reactivity. In particular, we observe a counterintuitive effect in which for low kinetic energy (below 22 eV), C60 bounces back without breaking more effectively at high temperature due to energy transfer from excited phonons. At higher kinetic energy (22 < K < 30 eV), for which cage rupture occurs, temperature enhances reactivity without playing a major role in the cage break. These results are in good agreement with ab-initio molecular dynamics simulations. SuMBE is thus a technique able to drive materials growth at low temperature regime.

  4. Theoretical studies on electronic states of Rh-C60. Possibility of a room-temperature organic ferromagnet.

    PubMed

    Nakano, S; Kitagawa, Y; Kawakami, T; Okumura, M; Nagao, H; Yamaguchi, K

    2004-01-01

    A possible mechanism for a ferromagnetic interaction in the rhombic (Rh) form of C60 (Rh-C60) is suggested on the basis of theoretical studies in relation to cage distortion of the C60 unit in the polymerized 2D-plane. Band structure calculations on Rh-C60 show that cage distortion leads to competition between diamagnetic and ferromagnetic states,which give rise to the possibility of thermally populating the ferromagnetic state.

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

    PubMed

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

    2014-08-21

    In both molecular and periodic solid-state systems there is a need for the accurate determination of the ionization potential and the electron affinity for systems ranging from light harvesting polymers and photocatalytic compounds to semiconductors. The development of a Green's function approach based on the coupled cluster (CC) formalism would be a valuable tool for addressing many properties involving many-body interactions along with their associated correlation functions. As a first step in this direction, we have developed an accurate and parallel efficient approach based on the equation of motion-CC technique. To demonstrate the high degree of accuracy and numerical efficiency of our approach we calculate the ionization potential and electron affinity for C60 and C70. Accurate predictions for these molecules are well beyond traditional molecular scale studies. We compare our results with experiments and both quantum Monte Carlo and GW calculations. PMID:25149783

  6. Self-healing phenomenon and dynamic hardness of C60-based nanocomposite coatings.

    PubMed

    Penkov, Oleksiy V; Pukha, Volodymyr E; Devizenko, Alexander Yu; Kim, Hae-Jin; Kim, Dae-Eun

    2014-05-14

    The phenomenon of surface self-healing in C60-based polymer coatings deposited by ion-beam assisted physical vapor deposition was investigated. Nanoindentation of the coatings led to the formation of a protrusion rather than an indent. This protrusion was accompanied by an abnormal shape of the force-distance curve, where the unloading curve lies above the loading curve due to an additional force applied in pulling the indenter out of the media. The coatings exhibited a nanocomposite structure that was strongly affected by the ratio of C60 ion and C60 molecular beam intensities during deposition. The coatings also demonstrated the dynamic hardness effect, where the effective value of the hardness depends significantly on the indentation speed.

  7. SEMICONDUCTOR DEVICES: CuPc/C60 heterojunction thin film optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Murtaza, Imran; Qazi, Ibrahim; Karimov, Khasan S.

    2010-06-01

    The optoelectronic properties of heterojunction thin film devices with ITO/CuPc/C60/Al structure have been investigated by analyzing their current-voltage characteristics, optical absorption and photocurrent. In this organic photovoltaic device, CuPc acts as an optically active layer, C60 as an electron-transporting layer and ITO and Al as electrodes. It is observed that, under illumination, excitons are formed, which subsequently drift towards the interface with C60, where an internal electric field is present. The excitons that reach the interface are subsequently dissociated into free charge carriers due to the electric field present at the interface. The experimental results show that in this device the total current density is a function of injected carriers at the electrode-organic semiconductor surface, the leakage current through the organic layer and collected photogenerated current that results from the effective dissociation of excitons.

  8. 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

  9. Arrangement of C60 via the self-assembly of post-functionalizable polyisocyanate block copolymer.

    PubMed

    Min, Joonkeun; Shah, Priyank N; Chae, Chang-Geun; Lee, Jae-Suk

    2012-12-13

    Poly(furfuryl isocyanate) (PFIC), which includes the reactive furan group, was synthesized by anionic polymerization using a sodium benzhydroxide (Na-BH), self-assembly initiator. We determined the optimum polymerization conditions by varying both the reaction time and the molar ratio of the monomer to the initiator. Block copolymer, poly(furfuryl isocyanate)-b-poly(n-hexyl isocyanate), was synthesized under optimized polymerization conditions. The PFIC was modified by Diels-Alder reactions with C60 for functionalization. Transmission electron microscopy (TEM) was used to study the self-assembly of block copolymers and modified block copolymer with C60. C60 formed highly ordered aggregates on the PFIC domains via self-assembly of the block copolymer.

  10. Linear pi-conjugated systems derivatized with C60-fullerene as molecular heterojunctions for organic photovoltaics.

    PubMed

    Roncali, Jean

    2005-06-01

    This tutorial review covers recent contributions in the area of linear pi-conjugated systems bound to fullerenes in view of their application as active materials in photovoltaic devices. The first part discusses the concepts of double-cable polymer and molecular hetero-junction and presents several examples of chemically or electrochemically synthesized C60-derivatized conjugated polymers. The second and main part of the article concerns the various classes of C60-derivatized pi-conjugated oligomers designed in view of their utilization in single-component photovoltaic devices. Thus, C60-containing pi-conjugated systems such as oligoarylenevinylenes, oligoaryleneethynylenes and oligothiophenes are discussed on the basis of the relationships between molecular structure, photophysical properties and performances of the derived photovoltaic devices. A brief last section presents some recent examples of surface-attached molecular hetero-junctions based on self-assembled monolayers and discusses possible routes for future research.

  11. Cytotoxicity and photocytotoxicity of structure-defined water-soluble C60/micelle supramolecular nanoparticles

    NASA Astrophysics Data System (ADS)

    Metanawin, Tanapak; Tang, Tian; Chen, Rongjun; Vernon, David; Wang, Xiaosong

    2011-06-01

    Well-defined, water-soluble C60/micelle hierarchical colloids with varied amounts of C60 sitting on the surface of micellar cores were prepared via the self-assembly of PS-b-PDMA block copolymer micelles and C60. The composites can generate a significant amount of reactive oxygen upon irradiation with red light. Cell studies showed that the colloids were either strongly associated with, or internalized by, the cells after 2 h incubation, but did not show obvious toxicity in the dark. In contrast, efficient cell killing was observed when the colloid-incubated cells were exposed to red light. This indicates that the supramolecular colloids are promising as photosensitizers for photodynamic cancer therapy.

  12. Direct detection of density of gap states in C60 single crystals by photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Bussolotti, Fabio; Yang, Janpeng; Hiramoto, Masahiro; Kaji, Toshihiko; Kera, Satoshi; Ueno, Nobuo

    2015-09-01

    We report on the direct and quantitative evaluation of density of gap states (DOGS) in large-size C60 single crystals by using ultralow-background, high-sensitivity ultraviolet photoemission spectroscopy. The charging of the crystals during photoionization was overcome using photoconduction induced by simultaneous laser irradiation. By comparison with the spectra of as-deposited and gas exposed C60 thin films the following results were found: (i) The DOGS near the highest occupied molecular orbital edge in the C60 single crystals (1019-1021states e V-1c m-3) mainly originates from the exposure to inert and ambient gas atmosphere during the sample preparation, storage, and transfer; (ii) the contribution of other sources of gap states such as structural imperfections at grain boundaries is negligible (<1018states e V-1c m-3) .

  13. Computational study of molecular properties of aggregates of C 60 and (16, 0) zigzag nanotube

    NASA Astrophysics Data System (ADS)

    Witek, Henryk A.; Trzaskowski, Bartosz; Małolepsza, Edyta; Morokuma, Keiji; Adamowicz, Ludwik

    2007-09-01

    Molecular properties for two aggregates of C 60 and a (16, 0) zigzag nanotube: (a) C 60 encapsulated in the nanotube, (b) C 60 attached to the outer wall of the nanotube, are studied using the self-consistent charge density-functional tight-binding method with additional dispersion correction. The binding energy for the encapsulated fullerene is -108.3 kcal/mol and for the attached fullerene, only -20.3 kcal/mol. The harmonic vibrational frequencies of the aggregates are found to be almost identical to those obtained for the non-interacting system. Very small extent of the changes upon interaction may pose a challenge to study the aggregated structures using experimental spectroscopic methods.

  14. Temporal Changes in Aqu/C60 Physical-Chemical, Deposition, and Transport Characteristics in Aqueous Systems

    EPA Science Inventory

    Little is known about how temporal changes in the physical–chemical properties of C60 aggregates formed in aqueous systems (termed aqu/C60) can impact transport pathways contributing to ecological exposures. In this study three aqu/C60 suspensions of short-term (100 days), interm...

  15. Magnetic field effect spectroscopy of C60-based films and devices

    NASA Astrophysics Data System (ADS)

    Gautam, Bhoj R.; Nguyen, Tho D.; Ehrenfreund, Eitan; Vardeny, Z. Valy

    2013-04-01

    We performed spectroscopy of the magnetic field effect (MFE) including magneto-photoinduced absorption (MPA) and magneto-photoluminescence (MPL) at steady state conditions in annealed and pristine fullerene C60 thin films, as well as magneto-conductance (MC) in organic diodes based on C60 interlayer. The hyperfine interaction has been shown to be the primary spin mixing mechanism for the MFE in the organics. In this respect, C60 is a unique material because 98.9% of the carbon atoms are 12C isotope, having spinless nucleus and thus lack hyperfine interaction. In spite of this, we obtained substantial MPA (up to ˜15%) and significant MC and MPL in C60 films and devices, and thus mechanisms other than the hyperfine interaction are responsible for the MFE in this material. Specifically, we found that the MFE(B) response is composed of narrow (˜10 mT) and broad (>100 mT) components. The narrow MFE(B) component is due to spin-dependent triplet exciton recombination in C60, which dominates the MPA(B) response at low pump intensities in films, or the MC response at small current densities in devices. In contrast, the broad MFE(B) component dominates the MPA(B) response at high pump intensities (or large current densities for MC(B)) and is attributed to spin mixing in the polaron pairs spin manifold due to g-factor mismatch between the electron- and hole-polarons in C60. Our results show that the organic MFE has a much broader scope than believed before.

  16. Electron spin relaxation of C60 monoanion in liquid solution: applicability of Kivelson-Orbach mechanism.

    PubMed

    Kundu, Krishnendu; Kattnig, Daniel R; Mladenova, Boryana; Grampp, Günter; Das, Ranjan

    2015-04-01

    We report the results of our investigation on the electron spin relaxation mechanism of the monoanion of C60 fullerene in liquid solution. The solvent chosen was carbon disulfide, which is rather uncommon in EPR spectroscopy but proved very useful here because of its liquid state over a wide temperature range. The conditions for exclusive formation of the monoanion of C60 in CS2 were first determined using electrochemical measurements. Using these results, only the monoanion of C60 was prepared by chemical reduction using Hg2I2/Hg as the reducing agent. The EPR line width was measured over a wide temperature range of 120-290 K. The line widths show weak dependence on temperature, changing by a factor of only about 2, over this temperature range. We show that the observed temperature dependence does not obey the Kivelson-Orbach mechanism of electron spin relaxation in liquids, applicable for radicals with low-lying, thermally accessible excited electronic states. The observed temperature dependence can be empirically fitted to an Arrhenius type of exponential function, from which an activation energy of 74 ± 3 cm(-1) is obtained. From the qualitative similarities in the characteristics of the spin relaxation rates of C60 monoanion radical and the cyclohexane type of cation radicals reported in the literature, we propose that a pseudorotation-induced electron spin relaxation process could be operating in the C60 monoanion radical in liquid solution. The low activation energy of 74 cm(-1) observed here is consistent with the pseudorotation barrier of C60 monoanion, estimated from reported Jahn-Teller energy levels. PMID:25789609

  17. The effect of morphology on electron field-effect mobility in disordered c60 thin films.

    PubMed

    Kwiatkowski, Joe J; Frost, Jarvist M; Nelson, Jenny

    2009-03-01

    We present a model of polycrystalline C60 field-effect transistors (FETs) that incorporates the microscopic structural and electronic details of the C60 films. We generate disordered polycrystalline thin films by simulating the physical-vapor deposition process. We simulate electron hopping transport using a Monte Carlo method and electronic structure calculations. Our model reproduces experimentally observed FET characteristics, including electrical characteristics, electrochemical potentials, and charge mobilities. Our results suggest that even relatively disordered films have charge mobilities that are only a factor of 2 smaller than mobilities in single crystals.

  18. Local-field effects and forbidden transitions in C60 solid thin films

    NASA Astrophysics Data System (ADS)

    Li, Dongmei; Velasquez, Steven; Schnatterly, S. E.

    1994-01-01

    We have measured the momentum-dependent inelastic-electron-scattering spectra of C60 solid thin films. These data allow the oscillator strength of dipole-forbidden transitions and the dispersion coefficient of the volume plasmon to be evaluated. In addition, we evaluate the complex molecular polarizability from the dielectric function using a point-dipole model for the local-field effects. The results are consistent with the presence and calculated energies of both dipolar and quadrupolar collective molecular excitations in molecular C60.

  19. The equilibrium geometry of A@C60: A test case for conventional density functional theory

    NASA Astrophysics Data System (ADS)

    Ma, Yong; Ai, Yuejie; Song, Xiuneng; Wang, Chuankui; Luo, Yi

    2014-01-01

    Potential energy surfaces (PESs) along the reaction pathway towards the center of CC bond between two six membered rings for ten different endohedral fullerenes A@C60 (A = H, C, O, S, N, P, He, Ne, Ar, Kr) have been studied by density functional theory (DFT) and Hartree-Fock (HF) method. The results show that no suitable method can consistently describe the interaction between atom A and carbon cage. The dispersion corrected DFT methods fail to describe the equilibrium geometry and PES of the complexes with light atoms. Nevertheless, the inclusion of the dispersion stabilizes the system as reflected by interaction energies (IEs) between atom A and C60.

  20. DFT Study of Structural and Electronic Properties of Endohedral Complexes of Group V Atoms with C60

    NASA Astrophysics Data System (ADS)

    Pahuja, Akshu; Srivastava, Sunita

    2013-09-01

    The structural and electronic properties of endohedral fullerenes formed by encapsulation of each of the group V elements inside the buckminsterfullerene cage have been investigated. The calculations reveal that all these species are thermodynamically stable, though the formation of Sb@C60 and Bi@C60 is slightly endothermic. The central atom preserves its electronic configuration and the quartet state. The energy gap and energy levels are perturbed by the inclusion of a foreign atom. The band gap of Sb@C60 and Bi@C60 is found to be significantly smaller than pristine C60, suggesting the reactivity of these complexes.

  1. Mechanism for doping induced p type C60 using thermally evaporated molybdenum trioxide (MoO3) as a dopant

    NASA Astrophysics Data System (ADS)

    Yang, Jin-Peng; Wang, Wen-Qing; Cheng, Li-Wen; Li, Yan-Qing; Tang, Jian-Xin; Kera, Satoshi; Ueno, Nobuo; Zeng, Xiang-hua

    2016-05-01

    Thermally evaporated molybdenum trioxide (MoO3) doped C60 films, which could change n type features of pristine C60 to form a p type mixed C60 layer, are investigated by x-ray and ultraviolet photoelectron spectroscopy. It is found that C60 HOMO progressively shifts closer to the Fermi level after increased MoO3 doping concentration, and final onset of C60 HOMO is pinned at binding energy of 0.20 eV, indicating the formation of p type C60 films. It is proposed that in charge transfer induced p type C60 formation, due to large electron affinity of MoO3 (6.37 eV), electrons from HOMO of C60 could easily transfer to MoO3 to form cations and therefore increase hole concentration, which could gradually push C60 HOMO to the Fermi level and finally form p type C60 films. Moreover, clear different types of C60 species have been confirmed from UPS spectra in highly doped films.

  2. A new way to synthesize superconducting metal-intercalated C60 and FeSe.

    PubMed

    Takahei, Yuuki; Tomita, Keitaro; Itoh, Yugo; Ashida, Keishi; Lee, Ji-Hyun; Nishimoto, Naoki; Kimura, Takumi; Kudo, Kazutaka; Nohara, Minoru; Kubozono, Yoshihiro; Kambe, Takashi

    2016-01-06

    Doping with the optimum concentration of carriers (electrons or holes) can modify the physical properties of materials. Therefore, improved ways to achieve carrier doping have been pursued extensively for more than 50 years. Metal-intercalation is one of the most important techniques for electron doping of organic / inorganic solids, and has produced superconductors from insulators and metallic solids. The most successful examples are metal-intercalated graphite and C60 superconductors. Metal intercalation has been performed using solid-reaction and liquid solvent techniques. However, precise control of the quantity of intercalants in the target solids can be difficult to achieve using these methods, as that quantity depends largely on the initial conditions. Here we report an electrochemical method for metal-intercalation, and demonstrate the preparation of superconductors using organic and inorganic materials (C60 and FeSe). The metal atoms are effectively intercalated into the spaces in C60 and FeSe solids by supplying an electric current between electrodes in a solvent that includes electrolytes. The recorded superconducting transition temperatures, Tc's, were the same as those of metal-intercalated C60 and FeSe prepared using solid-reaction or liquid solvent techniques. This technique may open a new avenue in the search for organic / inorganic superconductors.

  3. Improved spectrophotometric analysis of fullerenes C60 and C70 in high-solubility organic solvents.

    PubMed

    Törpe, Alexander; Belton, Daniel J

    2015-01-01

    Fullerenes are among a number of recently discovered carbon allotropes that exhibit unique and versatile properties. The analysis of these materials is of great importance and interest. We present previously unreported spectroscopic data for C60 and C70 fullerenes in high-solubility solvents, including error bounds, so as to allow reliable colorimetric analysis of these materials. The Beer-Lambert-Bouguer law is found to be valid at all wavelengths. The measured data were highly reproducible, and yielded high-precision molar absorbance coefficients for C60 and C70 in o-xylene and o-dichlorobenzene, which both exhibit a high solubility for these fullerenes, and offer the prospect of improved extraction efficiency. A photometric method for a C60/C70 mixture analysis was validated with standard mixtures, and subsequently improved for real samples by correcting for light scattering, using a power-law fit. The method was successfully applied to the analysis of C60/C70 mixtures extracted from fullerene soot. PMID:25746811

  4. Trends in correlation and confinement impacts on the e-Xe@C60 generalized oscillator strengths

    NASA Astrophysics Data System (ADS)

    Dolmatov, Valeriy; Amusia, Miron; Chernysheva, Larissa

    2012-06-01

    The response of endohedral Xe@C60 to fast electron impact ionization is theoretically studied by calculating its 4d, 5s and 5p generalized oscillators strengths (GOS). The calculation methodology combines the plane wave Born approximation, single-electron Hartree-Fock approximation, and multi-electron random phase approximation with exchange, all in the presence of the C60 confinement. The confinement is accounted for in the framework of both a spherical δ-potential [1] and square-well-potential [2] models to evaluate the effect of the finite thickness of the C60 cage on said GOS's. Impressive confinement brought impact on the latter is revealed. Vitality of accounting for electron correlation in calculations of the Xe@C60 5s and 5p GOS's is demonstrated. Trends in contributions of multipolar transitions beyond dipole transitions in the calculated GOS's are unraveled. We challenge experimentalists to conduct corresponding measurements.[4pt] [1] M.Ya. Amusia, A. S. Baltenkov, and B. G. Krakov, Phys. Lett. A, 243, 99 (1998).[0pt] [2] V. K. Dolmatov, Adv. Quant. Chem. 58, 13 (2009).

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

    EPA Science Inventory

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

  6. Suspension and Characterization of Aqueous C60 Nanomaterials in Natural and Engineered Waters

    EPA Science Inventory

    Many current studies on the aqueous suspension of fullerene (aqu/C60) have used deionized water or simple salt solutions, and as a result little is know about the suspension of fullerene nanomatierals under environmentally relevant conditions, such as solutions that contain organ...

  7. Conformational, IR spectroscopic and electronic properties of conium alkaloids and their adducts with C60 fullerene

    NASA Astrophysics Data System (ADS)

    Zabolotnyi, M. A.; Prylutskyy, Yu I.; Poluyan, N. A.; Evstigneev, M. P.; Dovbeshko, G. I.

    2016-08-01

    Conformational, IR spectroscopic and electronic properties of the components of Conium alkaloids (Conium maculatum) in aqueous environment were determined by model calculations and experiment. With the help of FT-IR spectroscopy the possibility of formation of an adduct between γ-coniceine alkaloid and C60 fullerene was demonstrated, which is important for further application of conium analogues in biomedical purposes.

  8. 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

  9. Effect of Humic Acid and Sunlight on the Generation of aqu/C60

    EPA Science Inventory

    Little is known about the effect of sunlight and natural organic matter, such as humic acid, on the aqueous suspension of fullerene C60. This knowledge gap limits our ability to determine the environmental impact of potential environmental releases of these materials. Aqueous sus...

  10. A new way to synthesize superconducting metal-intercalated C60 and FeSe

    NASA Astrophysics Data System (ADS)

    Takahei, Yuuki; Tomita, Keitaro; Itoh, Yugo; Ashida, Keishi; Lee, Ji-Hyun; Nishimoto, Naoki; Kimura, Takumi; Kudo, Kazutaka; Nohara, Minoru; Kubozono, Yoshihiro; Kambe, Takashi

    2016-01-01

    Doping with the optimum concentration of carriers (electrons or holes) can modify the physical properties of materials. Therefore, improved ways to achieve carrier doping have been pursued extensively for more than 50 years. Metal-intercalation is one of the most important techniques for electron doping of organic / inorganic solids, and has produced superconductors from insulators and metallic solids. The most successful examples are metal-intercalated graphite and C60 superconductors. Metal intercalation has been performed using solid-reaction and liquid solvent techniques. However, precise control of the quantity of intercalants in the target solids can be difficult to achieve using these methods, as that quantity depends largely on the initial conditions. Here we report an electrochemical method for metal-intercalation, and demonstrate the preparation of superconductors using organic and inorganic materials (C60 and FeSe). The metal atoms are effectively intercalated into the spaces in C60 and FeSe solids by supplying an electric current between electrodes in a solvent that includes electrolytes. The recorded superconducting transition temperatures, Tc’s, were the same as those of metal-intercalated C60 and FeSe prepared using solid-reaction or liquid solvent techniques. This technique may open a new avenue in the search for organic / inorganic superconductors.

  11. UV Irradiation and Humic Acid Mediate Aggregation of Aqueous Fullerene (nC60) Nanoparticles

    EPA Science Inventory

    The transport and fate of engineered nanomaterials is affected by multiple environmental factors, including sunlight and natural organic matter. In this study, the initial aggregation kinetics of aqueous fullerene (nC60) nanoparticles before and after UVA irradiation was investig...

  12. Preparation, surface characteristics and electrochemical properties of electrophoretically deposited C60 films

    SciTech Connect

    Kutner, Wlodzimierz; Pieta, Piotr; Nowakowski, Robert; Sobczak, Janusz W.; Kaszkur, Zbigniew

    2005-09-27

    Thin fullerene films of controlled roughness were electrophoretically deposited from C60 suspensions formed in mixed toluene-ethanol solutions. Mass of the deposited films, determined by piezoelectric microgravimetry (PM) with the use of an electrochemical quartz crystal microbalance, exponentially increased with time. Size of the AFM imaged C60 grains in the films depended both on time of C60 aggregation in bulk solution prior to deposition and strength of the electric field applied. In the accessible potential range, cyclic voltammetry (CV) curves for the films in 0.1 M (TBA)PF6, in acetonitrile, featured four main cathodic peaks formed during the negative potential excursion. These peaks corresponded to four one-electron reductions. Simultaneously recorded PM and CV curves showed an overall mass decrease, corresponding to stepwise C60 electroreduction and the complete dissolution of the C{sub 60}{sup 3-} film. The CV, XPS and XRD analyses indicated the film swelling and reversible ingress of both TBA+ counter- and PF{sub 6}{sup -} co-ion into the C{sub 60}{sup -} film.

  13. Decorating (C60)n+, n = 1–3, with CO2 at low temperatures: Sterically enhanced physisorption☆

    PubMed Central

    Mauracher, A.; Kaiser, A.; Probst, M.; Zöttl, S.; Daxner, M.; Postler, J.; Goulart, M.M.; Zappa, F.; Bohme, D.K.; Scheier, P.

    2013-01-01

    Multiple attachment of CO2 to the monomer, dimer and trimer cations of C60 has been observed in the mass spectra of He nanodroplets sequentially doped with C60 and CO2 and exposed to electron ionization at 50 eV. Remarkable anomalies were seen in the ion yield for CO2 coverage for (C60)2+(CO2)8 and (C60)3+(CO2)1,2. These provide insight into the influence of steric properties on the nature of physisorption. The enhanced stabilities of (C60)2+(CO2)8 and (C60)3+(CO2)1,2 are attributed to physisorption inside the “groove” of the dimer and the two “dimples” in the trimer cations of C60. Molecular dynamics simulations provide a qualitative assessment of the observed physisorption and a useful visualization of structural aspects. PMID:25844047

  14. NMR Study of the Superconducting Gap Variation near the Mott Transition in Cs3C60

    NASA Astrophysics Data System (ADS)

    Wzietek, P.; Mito, T.; Alloul, H.; Pontiroli, D.; Aramini, M.; Riccò, M.

    2014-02-01

    Former extensive studies of superconductivity in the A3C60 compounds, where A is an alkali metal, have led one to consider that Bardeen-Cooper-Schrieffer electron-phonon pairing prevails in those compounds, though the incidence of electronic Coulomb repulsion has been highly debated. The discovery of two isomeric fulleride compounds Cs3C60 which exhibit a transition with pressure from a Mott insulator (MI) to a superconducting (SC) state clearly reopens that question. Using pressure (p) as a single control parameter of the C60 balls lattice spacing, one can now study the progressive evolution of the SC properties when the electronic correlations are increased towards the critical pressure pc of the Mott transition. We have used C13 and Cs133 NMR measurements on the cubic phase A15-Cs3C60 just above pc=5.0(3) kbar, where the SC transition temperature Tc displays a dome shape with decreasing cell volume. From the T dependence below Tc of the nuclear spin lattice relaxation rate (T1)-1 we determine the electronic excitations in the SC state, that is 2Δ, the gap value. The latter is found to be largely enhanced with respect to the Bardeen-Cooper-Schrieffer value established in the case of dense A3C60 compounds. It even increases slightly with decreasing p towards pc, where Tc decreases on the SC dome, so that 2Δ /kBTc increases regularly upon approaching the Mott transition. These results bring clear evidence that the increasing correlations near the Mott transition are not significantly detrimental to superconductivity. They rather suggest that repulsive electron interactions might even reinforce elecron-phonon superconductivity, being then partly responsible for the large Tc values, as proposed by theoretical models taking the electronic correlations as a key ingredient.

  15. X-ray observation of a helium atom and placing a nitrogen atom inside He@C60 and He@C70.

    PubMed

    Morinaka, Yuta; Sato, Satoru; Wakamiya, Atsushi; Nikawa, Hidefumi; Mizorogi, Naomi; Tanabe, Fumiyuki; Murata, Michihisa; Komatsu, Koichi; Furukawa, Ko; Kato, Tatsuhisa; Nagase, Shigeru; Akasaka, Takeshi; Murata, Yasujiro

    2013-01-01

    Single crystal X-ray analysis has been used as a powerful method to determine the structure of molecules. However, crystallographic data containing helium has not been reported, owing to the difficulty in embedding helium into crystalline materials. Here we report the X-ray diffraction study of He@C60 and the clear observation of a single helium atom inside C60. In addition, the close packing of a helium atom and a nitrogen atom inside fullerenes is realized using two stepwise insertion techniques, that is, molecular surgery to synthesize the fullerenes encapsulating a helium atom, followed by nitrogen radio-frequency plasma methods to generate the fullerenes encapsulating both helium and nitrogen atoms. Electron spin resonance analysis reveals that the encapsulated helium atom has a small but detectable influence on the electronic properties of the highly reactive nitrogen atom coexisting inside the fullerene, suggesting the potential usage of helium for controlling electronic properties of reactive species.

  16. Computer simulations of material ejection during C60 and Arm bombardment of octane and β-carotene

    NASA Astrophysics Data System (ADS)

    Palka, G.; Kanski, M.; Maciazek, D.; Garrison, B. J.; Postawa, Z.

    2015-06-01

    Molecular dynamics (MD) computer simulations are used to investigate material ejection and fragment formation during keV C60 and Arm (m = 60, 101, 205, 366, 872 and 2953) bombardment of organic solids composed from octane and β-carotene molecules at 0° and 45° impact angle. Both systems are found to sputter efficiently. For the octane system, material removal occurs predominantly by ejection of intact molecules, while fragment emission is a significant ejection channel for β-carotene. A difference in the molecular dimensions is proposed to explain this observation. It has been shown that the dependence of the sputtering yield Y on the primary kinetic energy E and the cluster size n can be expressed in a simplified form if represented in reduced units. A linear and nonlinear dependence of the Y/n on the E/n are identified and the position of the transition point from the linear to nonlinear regions depends on the size of the cluster projectile. The impact angle has a minor influence on the shape of the simplified representation.

  17. Recent Advances in Electrochemical Biosensors Based on Fullerene-C60 Nano-Structured Platforms.

    PubMed

    Pilehvar, Sanaz; De Wael, Karolien

    2015-11-23

    Nanotechnology is becoming increasingly important in the field of (bio)sensors. The performance and sensitivity of biosensors is greatly improved with the integration of nanomaterials into their construction. Since its first discovery, fullerene-C60 has been the object of extensive research. Its unique and favorable characteristics of easy chemical modification, conductivity, and electrochemical properties has led to its tremendous use in (bio)sensor applications. This paper provides a concise review of advances in fullerene-C60 research and its use as a nanomaterial for the development of biosensors. We examine the research work reported in the literature on the synthesis, functionalization, approaches to nanostructuring electrodes with fullerene, and outline some of the exciting applications in the field of (bio)sensing.

  18. 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.

  19. Novel facile method for obtaining CdSe/polyaniline/C60 composite materials

    NASA Astrophysics Data System (ADS)

    Rusen, Edina; Diacon, Aurel; Mocanu, Alexandra; Nistor, Leona Cristina

    2016-08-01

    This study presents a novel method for the oxidative polymerization of aniline (ANI) by employing fullerene C60/cadmium selenide (CdSe) quantum dots, as promoting agent of the polymerization system. The polymerization initiation mechanism is based on the difference between the HOMO-LUMO energy levels of the components which permits the formation of a continuous donor-acceptor exchange. Both the polymerization reaction evolution and the molecular weights of the obtained polymers have been characterized. The novelty of the paper consists in the synthesis of a novel nano-composite material through a novel polymerization technique. The resulting material containing PANI, CdSe quantum dots and C60 has been characterized by UV-Vis, NIR, fluorescence, TEM and GPC analyses.

  20. Unravelling the multilayer growth of the fullerene C60 in real time

    NASA Astrophysics Data System (ADS)

    Bommel, S.; Kleppmann, N.; Weber, C.; Spranger, H.; Schäfer, P.; Novak, J.; Roth, S. V.; Schreiber, F.; Klapp, S. H. L.; Kowarik, S.

    2014-11-01

    Molecular semiconductors are increasingly used in devices, but understanding of elementary nanoscopic processes in molecular film growth is in its infancy. Here we use real-time in situ specular and diffuse X-ray scattering in combination with kinetic Monte Carlo simulations to study C60 nucleation and multilayer growth. We determine a self-consistent set of energy parameters describing both intra- and interlayer diffusion processes in C60 growth. This approach yields an effective Ehrlich-Schwoebel barrier of EES=110 meV, diffusion barrier of ED=540 meV and binding energy of EB=130 meV. Analysing the particle-resolved dynamics, we find that the lateral diffusion is similar to colloids, but characterized by an atom-like Schwoebel barrier. Our results contribute to a fundamental understanding of molecular growth processes in a system, which forms an important intermediate case between atoms and colloids.

  1. MAPLE preparation and characterization of mixed arylenevinylene based oligomers:C60 layers

    NASA Astrophysics Data System (ADS)

    Stanculescu, A.; Socol, G.; Vacareanu, L.; Socol, M.; Rasoga, O.; Breazu, C.; Girtan, M.; Stanculescu, F.

    2016-06-01

    This paper presents some studies about the preparation by matrix-assisted pulsed laser evaporation (MAPLE) of mixed layers based on two arylenevinylene oligomers, 1,4-bis [4-(N,N‧-diphenylamino)phenylvinyl] benzene (L78) and 3,3‧-bis(N-hexylcarbazole)vinylbenzene (L13) as donor and buckminsterfullerene (C60) as acceptor, blended in three different weight ratios: 1:1, 1:2 and 1:3. The optical, morphological, structural and electrical properties of these mixed layers have been investigated emphasizing the effect of the layer composition and of the significant degree of disorder. I-V characteristics have revealed typically solar cell behaviour for the heterostructures prepared with mixed layers containing L78 (L13) and fullerene blended in a weight ratio of 1:2. The solar cell structure glass/ITO/L13:C60/Al has shown the best parameters.

  2. Cyclotetrahalo-p-phenylenes: simulations of halogen substituted cycloparaphenylenes and their interaction with C60.

    PubMed

    Rio, J; Erbahar, D; Rayson, M; Briddon, P; Ewels, C P

    2016-08-17

    Density functional calculations are used to study the role of edge-functionalization on the structure and electronic properties of cycloparaphenylene (CPPs) containing from six to twenty benzenoid rings. We substitute hydrogen by the halogens fluorine, chlorine and bromine. The resultant Cyclotetrahalo-p-phenylenes are compared with their hydrogenated equivalents, related linear paraphenyl and fluoro-paraphenyl polymers, and functionalised armchair edges in graphene nanoribbons. Notably we consider both structural and electronic evolution. Finally we examine C60@[10]CPP, i.e. C60 encapsulated within [10]CPP, with the various ring terminations. The effect of halogenation on electronic level position around the gap strongly affects their capacity to form donor-acceptor pairs with fullerenes. PMID:27498723

  3. Novel facile method for obtaining CdSe/polyaniline/C60 composite materials

    PubMed Central

    Rusen, Edina; Diacon, Aurel; Mocanu, Alexandra; Nistor, Leona Cristina

    2016-01-01

    This study presents a novel method for the oxidative polymerization of aniline (ANI) by employing fullerene C60/cadmium selenide (CdSe) quantum dots, as promoting agent of the polymerization system. The polymerization initiation mechanism is based on the difference between the HOMO-LUMO energy levels of the components which permits the formation of a continuous donor-acceptor exchange. Both the polymerization reaction evolution and the molecular weights of the obtained polymers have been characterized. The novelty of the paper consists in the synthesis of a novel nano-composite material through a novel polymerization technique. The resulting material containing PANI, CdSe quantum dots and C60 has been characterized by UV-Vis, NIR, fluorescence, TEM and GPC analyses. PMID:27572228

  4. Epitaxial Growth of an Organic p-n Heterojunction: C60 on Single-Crystal Pentacene.

    PubMed

    Nakayama, Yasuo; Mizuno, Yuta; Hosokai, Takuya; Koganezawa, Tomoyuki; Tsuruta, Ryohei; Hinderhofer, Alexander; Gerlach, Alexander; Broch, Katharina; Belova, Valentina; Frank, Heiko; Yamamoto, Masayuki; Niederhausen, Jens; Glowatzki, Hendrik; Rabe, Jürgen P; Koch, Norbert; Ishii, Hisao; Schreiber, Frank; Ueno, Nobuo

    2016-06-01

    Designing molecular p-n heterojunction structures, i.e., electron donor-acceptor contacts, is one of the central challenges for further development of organic electronic devices. In the present study, a well-defined p-n heterojunction of two representative molecular semiconductors, pentacene and C60, formed on the single-crystal surface of pentacene is precisely investigated in terms of its growth behavior and crystallographic structure. C60 assembles into a (111)-oriented face-centered-cubic crystal structure with a specific epitaxial orientation on the (001) surface of the pentacene single crystal. The present experimental findings provide molecular scale insights into the formation mechanisms of the organic p-n heterojunction through an accurate structural analysis of the single-crystalline molecular contact.

  5. Recent Advances in Electrochemical Biosensors Based on Fullerene-C60 Nano-Structured Platforms

    PubMed Central

    Pilehvar, Sanaz; De Wael, Karolien

    2015-01-01

    Nanotechnology is becoming increasingly important in the field of (bio)sensors. The performance and sensitivity of biosensors is greatly improved with the integration of nanomaterials into their construction. Since its first discovery, fullerene-C60 has been the object of extensive research. Its unique and favorable characteristics of easy chemical modification, conductivity, and electrochemical properties has led to its tremendous use in (bio)sensor applications. This paper provides a concise review of advances in fullerene-C60 research and its use as a nanomaterial for the development of biosensors. We examine the research work reported in the literature on the synthesis, functionalization, approaches to nanostructuring electrodes with fullerene, and outline some of the exciting applications in the field of (bio)sensing. PMID:26610583

  6. Photodegradation of the electronic structure of PCBM and C60 films in air

    NASA Astrophysics Data System (ADS)

    Anselmo, Ana S.; Dzwilewski, Andrzej; Svensson, Krister; Moons, Ellen

    2016-05-01

    Fullerenes are common electron acceptors in organic solar cells. Here the photostability in air of the electronic structures of spin-coated PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) and evaporated C60 films are studied using ultraviolet photoelectron spectroscopy (UPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. After exposing these materials in air to simulated sunlight, the filled and empty molecular orbitals are strongly altered, indicating that the conjugated π-system of the C60-cage has degraded. Even a few minutes in normal lab light induces changes. These results stress the importance of protecting fullerene-based films from light and air during processing, operation, and storage.

  7. Electronic communication in tetrathiafulvalene (TTF)/C60 systems: toward molecular solar energy conversion materials?

    PubMed

    Martín, Nazario; Sánchez, Luis; Herranz, María Angeles; Illescas, Beatriz; Guldi, Dirk M

    2007-10-01

    The covalent connection of the electron acceptor C 60 to p-quinonoid pi-extended tetrathiafulvalenes (exTTFs) has allowed for the preparation of new photo- and electroactive conjugates able to act as artificial photosynthetic systems and active molecular materials in organic photovoltaics. The gain of aromaticity undergone by the pi-extended TTF unit in the oxidation process results in highly stabilized radical ion pairs, namely, C 60 (*-)/exTTF (*+). Lifetimes for such charge-separated states, ranging from a few nanoseconds to hundreds of microseconds, have been achieved by rationally modifying the nature of the chemical spacers. These long-lived radical pairs are called to play an important role for the conversion of sunlight into chemical or electrical power.

  8. Temperature-dependent nucleation and capture-zone scaling of C 60 on silicon oxide

    NASA Astrophysics Data System (ADS)

    Groce, M. A.; Conrad, B. R.; Cullen, W. G.; Pimpinelli, A.; Williams, E. D.; Einstein, T. L.

    2012-01-01

    Submonolayer films of C 60 have been deposited on ultrathin SiO 2 films for the purpose of characterizing the initial stages of nucleation and growth as a function of temperature. Capture zones extracted from the initial film morphology were analyzed using both the gamma and generalized Wigner distributions. The calculated critical nucleus size i of the C 60 islands was observed to change over the temperature range 298 K to 483 K. All fitted values of i were found to be between 0 and 1, representing stable monomers and stable dimers, respectively. With increasing temperature of film preparation, we observed i first increasing through this range and then decreasing. We discuss possible explanations of this reentrant-like behavior.

  9. Novel facile method for obtaining CdSe/polyaniline/C60 composite materials.

    PubMed

    Rusen, Edina; Diacon, Aurel; Mocanu, Alexandra; Nistor, Leona Cristina

    2016-01-01

    This study presents a novel method for the oxidative polymerization of aniline (ANI) by employing fullerene C60/cadmium selenide (CdSe) quantum dots, as promoting agent of the polymerization system. The polymerization initiation mechanism is based on the difference between the HOMO-LUMO energy levels of the components which permits the formation of a continuous donor-acceptor exchange. Both the polymerization reaction evolution and the molecular weights of the obtained polymers have been characterized. The novelty of the paper consists in the synthesis of a novel nano-composite material through a novel polymerization technique. The resulting material containing PANI, CdSe quantum dots and C60 has been characterized by UV-Vis, NIR, fluorescence, TEM and GPC analyses. PMID:27572228

  10. Unique Separation Behavior of a C60 Fullerene-Bonded Silica Monolith Prepared by an Effective Thermal Coupling Agent.

    PubMed

    Kubo, Takuya; Murakami, Yoshiki; Tsuzuki, Madoka; Kobayashi, Hiroshi; Naito, Toyohiro; Sano, Tomoharu; Yan, Mingdi; Otsuka, Koji

    2015-12-01

    Herein, we report a newly developed C60 fullerene-bonded silica monolith in a capillary with unique retention behavior due to the structure of C60 fullerene. N-Hydroxysuccinimide (NHS)-conjugated C60 fullerene was successfully synthesized by a thermal coupling agent, perfluorophenyl azide (PFPA), and assigned by spectroscopic analyses. Then, NHS-PFPA-C60 fullerene was attached onto the surface of a silica monolith in a capillary. The capillary provided specific separation ability for polycyclic aromatic hydrocarbons in liquid chromatography by an effective π-π interaction. Furthermore, corannulene, which has a hemispherical structure, was selectively retained in the capillary based on the specific structural recognition due to the spherical C60 fullerene. This is the first report revealing the spherical recognition ability by C60 fullerene in liquid chromatographic separation.

  11. Ab-initio modeling of an anion C- 60 pseudopotential for fullerene-based compounds

    NASA Astrophysics Data System (ADS)

    Vrubel, Ivan I.; Polozkov, Roman G.; Ivanov, Vadim K.

    2016-08-01

    An anion C- 60 pseudopotential is determined from an ab-initio-based approach. First, ab-initio calculations are performed to calculate the electronic charge density and the total electrostatic potential. Second, the effective dependence of the pseudopotential on the radial degree of freedom is extracted from the angular average of the total electrostatic potential. Finally, the resulting effective pseudopotential is fitted to a simple analytical form which can be applied in further dynamical simulations of fullerene-based compounds.

  12. Icosahedral symmetry breaking: C(60) to C(84), C(108) and to related nanotubes.

    PubMed

    Bodner, Mark; Bourret, Emmanuel; Patera, Jiri; Szajewska, Marzena

    2015-05-01

    This paper completes the series of three independent articles [Bodner et al. (2013). Acta Cryst. A69, 583-591, (2014), PLOS ONE, 10.1371/journal.pone.0084079] describing the breaking of icosahedral symmetry to subgroups generated by reflections in three-dimensional Euclidean space {\\bb R}^3 as a mechanism of generating higher fullerenes from C60. The icosahedral symmetry of C60 can be seen as the junction of 17 orbits of a symmetric subgroup of order 4 of the icosahedral group of order 120. This subgroup is noted by A1 × A1, because it is isomorphic to the Weyl group of the semi-simple Lie algebra A1 × A1. Thirteen of the A1 × A1 orbits are rectangles and four are line segments. The orbits form a stack of parallel layers centered on the axis of C60 passing through the centers of two opposite edges between two hexagons on the surface of C60. These two edges are the only two line segment layers to appear on the surface shell. Among the 24 convex polytopes with shell formed by hexagons and 12 pentagons, having 84 vertices [Fowler & Manolopoulos (1992). Nature (London), 355, 428-430; Fowler & Manolopoulos (2007). An Atlas of Fullerenes. Dover Publications Inc.; Zhang et al. (1993). J. Chem. Phys. 98, 3095-3102], there are only two that can be identified with breaking of the H3 symmetry to A1 × A1. The remaining ones are just convex shells formed by regular hexagons and 12 pentagons without the involvement of the icosahedral symmetry.

  13. 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.

  14. Constrained LDA ab-initio calculation of screening of charging energy in C60

    NASA Astrophysics Data System (ADS)

    Sau, Jay; Neaton, Jeffrey; Khoo, K. H.; Choi, Hyoung; Louie, Steven; Cohen, Marvin

    2006-03-01

    Recent measurements and theoretical calculations of the electronic properties of C60 on metal substrates have shown that the electron-electron repulsion parameter U, which determines the coulomb blockade transport properties, is strongly screened in the presence of a metal susbtrate. Since standard Density Functional Theory calculations treat this charging energy in a mean field sense, it ignores the discreteness of the charge on the C60 that is critical to coulomb blockade. To account for the effect of the screened U in transport experiments we calculate the charging energy of C60 in a few environments using a constrained LDA approach and explore the implications for coulomb blockade transport phenomena. This work was supported by National Science Foundation Grant No. DMR04-39768 and by the Director, Office of Science, Office of Basic Energy Sciences, Division of Material Sciences and Engineering, U. S Department of Energy under Contract No. DE-AC03-76SF00098. Computational resources have been provided by DOE at the National Energy Research Scientific Computing Center(NERSC)

  15. Theoretical study of C60 as catalyst for dehydrogenation in LiBH4.

    PubMed

    Scheicher, Ralph H; Li, Sa; Araujo, C Moyses; Blomqvist, Andreas; Ahuja, Rajeev; Jena, Puru

    2011-08-19

    Complex light metal hydrides possess many properties which make them attractive as a storage medium for hydrogen, but typically catalysts are required to lower the hydrogen desorption temperature and to facilitate hydrogen uptake in the form of a reversible reaction. The overwhelming focus in the search for catalysing agents has been on compounds containing titanium, but the precise mechanism of their actions remains somewhat obscure. A recent experiment has now shown that fullerenes (C(60)) can also act as catalysts for both hydrogen uptake and release in lithium borohydride (LiBH(4)). In an effort to understand the involved mechanism, we have employed density functional theory to carry out a detailed study of the interaction between this complex metal hydride and the carbon nanomaterial. Considering a stepwise reduction of the hydrogen content in LiBH(4), we find that the presence of C(60) can lead to a substantial reduction of the involved H-removal energies. This effect is explained as a consequence of the interaction between the BH(x)( - ) complex and the C(60) entity. PMID:21788688

  16. Possible light-induced superconductivity in K3C60 at high temperature.

    PubMed

    Mitrano, M; Cantaluppi, A; Nicoletti, D; Kaiser, S; Perucchi, A; Lupi, S; Di Pietro, P; Pontiroli, D; Riccò, M; Clark, S R; Jaksch, D; Cavalleri, A

    2016-02-25

    The non-equilibrium control of emergent phenomena in solids is an important research frontier, encompassing effects such as the optical enhancement of superconductivity. Nonlinear excitation of certain phonons in bilayer copper oxides was recently shown to induce superconducting-like optical properties at temperatures far greater than the superconducting transition temperature, Tc (refs 4-6). This effect was accompanied by the disruption of competing charge-density-wave correlations, which explained some but not all of the experimental results. Here we report a similar phenomenon in a very different compound, K3C60. By exciting metallic K3C60 with mid-infrared optical pulses, we induce a large increase in carrier mobility, accompanied by the opening of a gap in the optical conductivity. These same signatures are observed at equilibrium when cooling metallic K3C60 below Tc (20 kelvin). Although optical techniques alone cannot unequivocally identify non-equilibrium high-temperature superconductivity, we propose this as a possible explanation of our results.

  17. Guest encapsulation and coronene-C60 exchange in supramolecular zinc porphyrin tweezers, grids and prisms.

    PubMed

    Samanta, Soumen K; Schmittel, Michael

    2013-05-21

    Using a variant of the HETPHEN concept, heteroleptic 2D and 3D metallosupramolecular structures, such as tweezer T, grid G and tetragonal prism P, were fabricated quantitatively and characterised by (1)H NMR, (13)C NMR, (1)H-(1)H COSY, DOSY as well as ESI-MS. All structures encapsulate C60, with P showing the highest binding affinity (Kassoc = 3.3 × 10(6) M(-1)). The association constant increases along the series T < G < P, most likely due to the enhanced structural rigidity and better coplanarity of the two zinc porphyrin units. In contrast to T and G, the tetragonal prism P shows notable encapsulation of coronene (Kassoc = 1.1 × 10(4) M(-1)). In T and G, on the other hand, complexation of coronene is kinetically inhibited by the bulky mesityl rings at the porphyrin periphery. As illustrated in the facile displacement of coronene by C60 in coronene@P to furnish C60@P, P behaves as a flexible and guest-adaptive host.

  18. Superconductivity of Rb 3 C 60 : breakdown of the Migdal-Eliashberg theory

    NASA Astrophysics Data System (ADS)

    Cappelluti, E.; Grimaldi, C.; Pietronero, L.; Strässler, S.; Ummarino, G. A.

    2001-06-01

    In this paper, through an exhaustive analysis within the Migdal-Eliashberg theory, we show the incompatibility of experimental data of Rb3C60 with the basic assumptions of the standard theory of superconductivity. For different models of the electron-phonon spectral function α2F(Ω) we solve numerically the Eliashberg equations to find which values of the electron-phonon coupling λ, of the logarithmic phonon frequency and of the Coulomb pseudopotential μ* reproduce the experimental data of Rb3C60. We find that the solutions are essentially independent of the particular shape of α2F(Ω) and that, to explain the experimental data of Rb3C60, one has to resort to extremely large couplings: λ = 3.0+/-0.8. This results differs from the usual partial analyses reported up to now and we claim that this value exceeds the maximum allowed λ compatible with the crystal lattice stability. Moreover, we show quantitatively that the obtained values of λ and strongly violate Migdal's theorem and consequently are incompatible with the Migdal-Eliashberg theory. One has therefore to consider the generalization of the theory of superconductivity in the nonadiabatic regime to account for the experimental properties of fullerides.

  19. Transformation-deformation bands in C60 after the treatment in a shear diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Kulnitskiy, B. A.; Blank, V. D.; Levitas, V. I.; Perezhogin, I. A.; Popov, M. Yu; Kirichenko, A. N.; Tyukalova, E. V.

    2016-04-01

    The C60 fullerene has been investigated by high-resolution transmission electron microscopy and electron energy loss spectroscopy in a shear diamond anvil cell after applying pressure and shear deformation treatment of fcc phase. Shear transformation-deformation bands are revealed consisting of shear-strain-induced nanocrystals of linearly polymerized fullerene and polytypes, the triclinic, monoclinic, and hcp C60, fragments of amorphous structures, and voids. Consequently, after pressure release, the plastic strain retains five high pressure phases, which is potentially important for their engineering applications. Localized shear deformation initially seems contradictory because high pressure phases of C60 are stronger than the initial low pressure phase. However, this was explained by transformation-induced plasticity during localized phase transformations. It occurs due to a combination of applied stresses and internal stresses from a volume reduction during phase transformations. Localized phase transformations and plastic shear deformation promote each other, which produce positive mechanochemical feedback and cascading transformation-deformation processes. Since the plastic shear in a band is much larger than is expected based on the torsion angle, five phase transformations occur in the same region with no transformation outside the band. The results demonstrate that transformation kinetics cannot be analyzed in terms of prescribed shear, and methods to measure local shear should be developed.

  20. White-Rot Basidiomycete-mediated Decomposition of C60 Fullerol

    PubMed Central

    Schreiner, Kathryn M.; Filley, Timothy R.; Blanchette, Robert A.; Bowen, Brenda Beitler; Bolskar, Robert D.; Hockaday, William C.; Masiello, Caroline A.; Raebiger, James W.

    2009-01-01

    Industrially produced carbon-based nanomaterials (CNM), including fullerenes and nanotubes, will be introduced into the environment in increasing amounts in the next decades. One likely environmental chemical transformation of C60 is oxidation to C60 fullerol through both abiotic- and biotic-mediated means. Unfortunately, knowledge of the environmental fate of oxidized CNM is lacking. This study used bulk and compound specific 13C stable isotope ratio mass spectrometry techniques and spectroradiometry analysis to examine the ability of two white rot basidiomycete fungi (Phlebia tremellosa and Trametes versicolor) to metabolize and degrade an oxygenated CNM, C60 fullerol. After 32 weeks of decay, both fungi were able to bleach and oxidize fullerol to CO2. Additionally, the fungi incorporated minor amounts of the fullerol carbon into lipid biomass. These findings are significant in that they represent the first report of direct biodegradation and utilization of any fullerene derivative and provide valuable information about the possible environmental fates of other CNM. PMID:19534129

  1. Photoelectron Spectroscopy and Electronic Structures of Fullerene Oxides: C60Ox- (x=1-3)

    SciTech Connect

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

    2005-12-15

    We report a photoelectron spectroscopy (PES) study on a series of fullerene oxides, C600x- (x = 1-3). The PES spectra reveal one isomer for C600x-, two isomers for C6002-, and multiple isomers for C6003-. Compared to C60, the electronic structures of C600x are only slightly perturbed, resulting in similar anion photoelectron spectra. The electron affinity of C600x was observed to increase only marginally with the number of oxygen atoms, x, from 2.683 eV for C60, to 2.745 eV for C600, and 2.785 eV/2.820 eV for C6002 (two isomers). We also carried out theoretical calculations, which confirmed the observed isomers and showed that all the fullerene oxides are in the form of epoxide. The PES and theoretical calculations, as well as molecular orbital analysis, indicate that addition of oxygen atoms to the C60 cage only modifies the local carbon network and leave the rest of the fullerene cage largely intact geometrically and electronically.

  2. Growth and study of superconducting C60 compounds. Final report, October 1992-September 1995

    SciTech Connect

    Liu, J.Z.; Shelton, R.N.; Klavins, P.; Irons, S.H.; Chang, I.C.

    1995-12-01

    A home made semi-automatic feeding plasma arc reactor was used for the mass production fullerenes. Large, high quality single crystals of C60 up to 3mm in length have been grown by both the open-end and sealed vapor transport techniques. Millimeter-sized superconducting single crystals of K3C60 were successfully produced by a sophisticated vacuum doping method. Magnetic and superconducting properties were obtained. Information on the field and temperature dependences of the critical current density J(sub c) and the H(c1) have been reported. New compounds of Yb(x) C60 with x=1-6 were synthesized using a liquid ammonia route at low T and in an inert atmosphere. It turns out that these compounds are amorphous and have a spin glass behavior at a temperature T<15K. Finally, new superconductors with T(sub c) of 134K were found in the system of Tl(1-x)HgBa2Ca2Cu3O(8+y).

  3. 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.

  4. Adsorption of helium on isolated C60 and C70 anions

    NASA Astrophysics Data System (ADS)

    Harnisch, Martina; Weinberger, Nikolaus; Denifl, Stephan; Scheier, Paul; Echt, Olof

    2015-08-01

    Adsorption of helium on free, negatively charged fullerenes is studied in this work. Helium nanodroplets have been doped with fullerenes and ionised by electron attachment. For suitable experimental conditions, C-60 and C-70 anions are found to be complexed with a large number of helium atoms. Prominent anomalies in the ion abundances indicate the high stability of the commensurate 1×1 phase in which all hollow adsorption sites are occupied by one atom each. The adsorption energy for an additional helium atom is about 40% less than for atoms in the commensurate layer, similar to our previous findings for fullerene cations and in agreement with theoretical dissociation energies. Similarly, an anomaly in the adsorption energy occurs when 60 helium atoms are attached to C-60 or 65 to C-70. For C60, the anomaly coincides with the one observed for cationic complexes but for C70 it does not. Implications of these features are discussed in light of several theoretical studies of neutral and positively charged helium-fullerene complexes.

  5. Possible light-induced superconductivity in K3C60 at high temperature.

    PubMed

    Mitrano, M; Cantaluppi, A; Nicoletti, D; Kaiser, S; Perucchi, A; Lupi, S; Di Pietro, P; Pontiroli, D; Riccò, M; Clark, S R; Jaksch, D; Cavalleri, A

    2016-02-25

    The non-equilibrium control of emergent phenomena in solids is an important research frontier, encompassing effects such as the optical enhancement of superconductivity. Nonlinear excitation of certain phonons in bilayer copper oxides was recently shown to induce superconducting-like optical properties at temperatures far greater than the superconducting transition temperature, Tc (refs 4-6). This effect was accompanied by the disruption of competing charge-density-wave correlations, which explained some but not all of the experimental results. Here we report a similar phenomenon in a very different compound, K3C60. By exciting metallic K3C60 with mid-infrared optical pulses, we induce a large increase in carrier mobility, accompanied by the opening of a gap in the optical conductivity. These same signatures are observed at equilibrium when cooling metallic K3C60 below Tc (20 kelvin). Although optical techniques alone cannot unequivocally identify non-equilibrium high-temperature superconductivity, we propose this as a possible explanation of our results. PMID:26855424

  6. Nonequilibrium electron-vibration coupling and conductance fluctuations in a C60 junction

    NASA Astrophysics Data System (ADS)

    Ulstrup, Søren; Frederiksen, Thomas; Brandbyge, Mads

    2012-12-01

    We investigate chemical bond formation and conductance in a molecular C60 junction under finite bias voltage using first-principles calculations based on density functional theory and nonequilibrium Green's functions (DFT-NEGF). At the point of contact formation we identify a remarkably strong coupling between the C60 motion and the molecular electronic structure. This is only seen for positive sample bias, although the conductance itself is not strongly polarity dependent. The nonequilibrium effect is traced back to a sudden shift in the position of the voltage drop with a small C60 displacement. Combined with a vibrational heating mechanism we construct a model from our results that explain the polarity-dependent two-level conductance fluctuations observed in recent scanning tunneling microscopy (STM) experiments [N. Néel , Nano Lett.NALEFD1530-698410.1021/nl201327c 11, 3593 (2011)]. These findings highlight the significance of nonequilibrium effects in chemical bond formation/breaking and in electron-vibration coupling in molecular electronics.

  7. Effect of substrate temperature on the spin transport properties in C60-based spin valves.

    PubMed

    Li, Feng

    2013-08-28

    We report the effect of the substrate temperature on the magnetoresistance (MR) of C60-based spin-valve (SV) devices with the sandwich configuration of La0.67Sr0.33MnO3 (LSMO)/C60/cobalt (Co). The C60 interlayer deposited at different substrate temperatures resulted in four types of devices. We observed that all types of devices showed a monotonic increase in their MR ratio with the substrate temperature. Interestingly, an especially large MR (|-28.5%|) was obtained in the device fabricated at a higher substrate temperature, whereas for the other types of devices, the MR magnitudes were about a few percent. On the basis of the I-V measurements as well as SEM and AFM characteristics, we have found that the higher substrate temperature can cause many pits and hollows in the organic film, and these pits will increase the tunneling probability of spin-polarized carriers from one ferromagnetic electrode to the other.

  8. Effect of substrate temperature on the spin transport properties in C60-based spin valves.

    PubMed

    Li, Feng

    2013-08-28

    We report the effect of the substrate temperature on the magnetoresistance (MR) of C60-based spin-valve (SV) devices with the sandwich configuration of La0.67Sr0.33MnO3 (LSMO)/C60/cobalt (Co). The C60 interlayer deposited at different substrate temperatures resulted in four types of devices. We observed that all types of devices showed a monotonic increase in their MR ratio with the substrate temperature. Interestingly, an especially large MR (|-28.5%|) was obtained in the device fabricated at a higher substrate temperature, whereas for the other types of devices, the MR magnitudes were about a few percent. On the basis of the I-V measurements as well as SEM and AFM characteristics, we have found that the higher substrate temperature can cause many pits and hollows in the organic film, and these pits will increase the tunneling probability of spin-polarized carriers from one ferromagnetic electrode to the other. PMID:23895328

  9. [Interaction of C60 fullerene-polyvinylpyrrolidone complex and brain Aβ(1-42)-peptide in vitro].

    PubMed

    Bobylev, A G; Shatalin, Iu V; Vikhliantsev, I M; Bobyleva, L G; Gudkov, S V; Podlubnaia, Z A

    2014-01-01

    Using a spectrophotometric method changes occurring in solution containing brain Aβ(1-42)-peptide, fullerene C60, and polyvinylpyrrolidone were analyzed. Using the Bent-French method relative binding constants of fullerene C60 with Aβ(1-42)-peptide and polyvinylpyrrolidone with Aβ(1-42)- peptide were determined. These data suggest that Aβ(1-42)-peptide interacting with the C60 fullerene-polyvinylpyrrolidone complex partially displaces polyvinylpyrrolidone and generates a new three molecular compound.

  10. First prediction of inter-Coulombic decay of C60 inner vacancies through the continuum of confined atoms

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    Considering the photoionization of Ar@{{{C}}}60 and Kr@{{{C}}}60 endofullerenes, the decay of {{{C}}}60 innershell excitations through the outershell continuum of the confined atom via the inter-Coulombic decay (ICD) pathway is detailed. Excitations to atom-{{{C}}}60 hybrid states, when these states exist, can induce coherence between ICD and electron-transfer mediated decay (ETMD). This should be the dominant above-threshold decay process for a variety of confined systems, and the strength of these resonances is such that they should be amenable for study by photoelectron spectroscopy.

  11. 129Xe NMR chemical shift in Xe@C60 calculated at experimental conditions: essential role of the relativity, dynamics, and explicit solvent.

    PubMed

    Standara, Stanislav; Kulhánek, Petr; Marek, Radek; Straka, Michal

    2013-08-15

    The isotropic (129)Xe nuclear magnetic resonance (NMR) chemical shift (CS) in Xe@C60 dissolved in liquid benzene was calculated by piecewise approximation to faithfully simulate the experimental conditions and to evaluate the role of different physical factors influencing the (129)Xe NMR CS. The (129)Xe shielding constant was obtained by averaging the (129)Xe nuclear magnetic shieldings calculated for snapshots obtained from the molecular dynamics trajectory of the Xe@C60 system embedded in a periodic box of benzene molecules. Relativistic corrections were added at the Breit-Pauli perturbation theory (BPPT) level, included the solvent, and were dynamically averaged. It is demonstrated that the contribution of internal dynamics of the Xe@C60 system represents about 8% of the total nonrelativistic NMR CS, whereas the effects of dynamical solvent add another 8%. The dynamically averaged relativistic effects contribute by 9% to the total calculated (129)Xe NMR CS. The final theoretical value of 172.7 ppm corresponds well to the experimental (129)Xe CS of 179.2 ppm and lies within the estimated errors of the model. The presented computational protocol serves as a prototype for calculations of (129)Xe NMR parameters in different Xe atom guest-host systems.

  12. Progress towards a realistic theoretical description of C60 photoelectron-momentum imaging experiments using time-dependent density-functional theory

    NASA Astrophysics Data System (ADS)

    Wopperer, P.; Gao, C. Z.; Barillot, T.; Cauchy, C.; Marciniak, A.; Despré, V.; Loriot, V.; Celep, G.; Bordas, C.; Lépine, F.; Dinh, P. M.; Suraud, E.; Reinhard, P.-G.

    2015-04-01

    We have studied theoretical photoelectron-momentum distributions of C60 using time-dependent density functional theory (TDDFT) in real time and including a self-interaction correction. Our calculations furthermore account for a proper orientation averaging allowing a direct comparison with experimental results. To illustrate the capabilities of this direct (microscopic and time-dependent) approach, two very different photo-excitation conditions are considered: excitation with a high-frequency XUV light at 20 eV and with a low-frequency IR femtosecond pulse at 1.55 eV. The interaction with the XUV light leads to one-photon transitions and a linear ionization regime. In that situation, the spectrum of occupied single-electron states in C60 is directly mapped to the photoelectron spectrum. On the contrary, the IR pulse leads to multiphoton ionization in which only the two least-bound states contribute to the process. In both dynamical regimes (mono- and multiphoton), calculated and experimental angle-resolved photoelectron spectra compare reasonably well. The observed discrepancies can be understood by the theoretical underestimation of higher-order many-body interaction processes such as electron-electron scattering and by the fact that experiments are performed at finite temperature. These results pave the way to a multiscale description of the C60 ionization mechanisms that is required to render justice to the variety of processes observed experimentally for fullerene molecules.

  13. 129Xe NMR chemical shift in Xe@C60 calculated at experimental conditions: essential role of the relativity, dynamics, and explicit solvent.

    PubMed

    Standara, Stanislav; Kulhánek, Petr; Marek, Radek; Straka, Michal

    2013-08-15

    The isotropic (129)Xe nuclear magnetic resonance (NMR) chemical shift (CS) in Xe@C60 dissolved in liquid benzene was calculated by piecewise approximation to faithfully simulate the experimental conditions and to evaluate the role of different physical factors influencing the (129)Xe NMR CS. The (129)Xe shielding constant was obtained by averaging the (129)Xe nuclear magnetic shieldings calculated for snapshots obtained from the molecular dynamics trajectory of the Xe@C60 system embedded in a periodic box of benzene molecules. Relativistic corrections were added at the Breit-Pauli perturbation theory (BPPT) level, included the solvent, and were dynamically averaged. It is demonstrated that the contribution of internal dynamics of the Xe@C60 system represents about 8% of the total nonrelativistic NMR CS, whereas the effects of dynamical solvent add another 8%. The dynamically averaged relativistic effects contribute by 9% to the total calculated (129)Xe NMR CS. The final theoretical value of 172.7 ppm corresponds well to the experimental (129)Xe CS of 179.2 ppm and lies within the estimated errors of the model. The presented computational protocol serves as a prototype for calculations of (129)Xe NMR parameters in different Xe atom guest-host systems. PMID:23703381

  14. Excitations, optical absorption spectra, and optical excitonic gaps of heterofullerenes. I. C60, C59N+, and C48N12: theory and experiment.

    PubMed

    Xie, Rui-Hua; Bryant, Garnett W; Sun, Guangyu; Nicklaus, Marc C; Heringer, David; Frauenheim, Th; Manaa, M Riad; Smith, Vedene H; Araki, Yasuyuki; Ito, Osamu

    2004-03-15

    spectra of C(48)N(12) isomers is helpful in distinguishing the isomer structures required for applications in molecular electronics. For C(59)N(+) and C(48)N(12) as well as C(60), TD-DFT-TB yields reasonable agreement with TD-DFT calculations at a highly reduced cost. Our study suggests that C(60), C(59)N(+), and C(48)N(12), which differ in their optical gaps, have potential applications in polymer science, biology, and medicine as single-molecule fluorescent probes, in photovoltaics as the n-type emitter and/or p-type base of a p-n junction solar cell, and in nanoelectronics as fluorescence-based sensors and switches.

  15. Excitations, optical absorption spectra, and optical excitonic gaps of heterofullerenes. I. C60, C59N+, and C48N12: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Xie, Rui-Hua; Bryant, Garnett W.; Sun, Guangyu; Nicklaus, Marc C.; Heringer, David; Frauenheim, Th.; Manaa, M. Riad; Smith, Vedene H.; Araki, Yasuyuki; Ito, Osamu

    2004-03-01

    distinguishing the isomer structures required for applications in molecular electronics. For C59N+ and C48N12 as well as C60, TD-DFT-TB yields reasonable agreement with TD-DFT calculations at a highly reduced cost. Our study suggests that C60, C59N+, and C48N12, which differ in their optical gaps, have potential applications in polymer science, biology, and medicine as single-molecule fluorescent probes, in photovoltaics as the n-type emitter and/or p-type base of a p-n junction solar cell, and in nanoelectronics as fluorescence-based sensors and switches.

  16. Confirming a predicted selection rule in inelastic neutron scattering spectroscopy: the quantum translator-rotator H2 entrapped inside C60.

    PubMed

    Xu, Minzhong; Jiménez-Ruiz, Mónica; Johnson, Mark R; Rols, Stéphane; Ye, Shufeng; Carravetta, Marina; Denning, Mark S; Lei, Xuegong; Bačić, Zlatko; Horsewill, Anthony J

    2014-09-19

    We report an inelastic neutron scattering (INS) study of a H2 molecule encapsulated inside the fullerene C60 which confirms the recently predicted selection rule, the first to be established for the INS spectroscopy of aperiodic, discrete molecular compounds. Several transitions from the ground state of para-H2 to certain excited translation-rotation states, forbidden according to the selection rule, are systematically absent from the INS spectra, thus validating the selection rule with a high degree of confidence. Its confirmation sets a precedent, as it runs counter to the widely held view that the INS spectroscopy of molecular compounds is not subject to any selection rules. PMID:25279623

  17. Accurate calculation of chemical shifts in highly dynamic H2@C60 through an integrated quantum mechanics/molecular dynamics scheme.

    PubMed

    Jiménez-Osés, Gonzalo; García, José I; Corzana, Francisco; Elguero, José

    2011-05-20

    A new protocol combining classical MD simulations and DFT calculations is presented to accurately estimate the (1)H NMR chemical shifts of highly mobile guest-host systems and their thermal dependence. This strategy has been successfully applied for the hydrogen molecule trapped into C(60) fullerene, an unresolved and challenging prototypical case for which experimental values have never been reproduced. The dependence of the final values on the theoretical method and their implications to avoid over interpretation of the obtained results are carefully described.

  18. Distribution and biomarkers of carbon-14-labeled fullerene C60 ([(14) C(U)]C60 ) in female rats and mice for up to 30 days after intravenous exposure.

    PubMed

    Sumner, Susan C J; Snyder, Rodney W; Wingard, Christopher; Mortensen, Ninell P; Holland, Nathan A; Shannahan, Jonathan H; Dhungana, Suraj; Pathmasiri, Wimal; Han, Li; Lewin, Anita H; Fennell, Timothy R

    2015-12-01

    A comprehensive distribution study was conducted in female rats and mice exposed to a suspension of uniformly carbon-14-labeled C60 ([(14) C(U)]C60 ). Rodents were administered [(14) C(U)]C60 (~0.9 mg kg(-1) body weight) or 5% polyvinylpyrrolidone-saline vehicle alone via a single tail vein injection. Tissues were collected at 1 h and 1, 7, 14 and 30 days after administration. A separate group of rodents received five daily injections of suspensions of either [(14) C(U)]C60 or vehicle with tissue collection 14 days post exposure. Radioactivity was detected in over 20 tissues at all time points. The highest concentration of radioactivity in rodents at each time point was in liver, lungs and spleen. Elimination of [(14) C(U)]C60 was < 2% in urine and feces at any 24 h time points. [(14) C(U)]C60 and [(14) C(U)]C60 -retinol were detected in liver of rats and together accounted for ~99% and ~56% of the total recovered at 1 and 30 days postexposure, respectively. The blood radioactivity at 1 h after [(14) C(U)]C60 exposure was fourfold higher in rats than in mice; blood radioactivity was still in circulation at 30 days post [(14) C(U)]C60 exposure in both species (<1%). Levels of oxidative stress markers increased by 5 days after exposure and remained elevated, while levels of inflammation markers initially increased and then returned to control values. The level of cardiovascular marker von Willebrand factor, increased in rats, but remained at control levels in mice. This study demonstrates that [(14) C(U)]C60 is retained in female rodents with little elimination by 30 days after i.v. exposure, and leads to systemic oxidative stress.

  19. Protective effect of reduced glutathione C60 derivative against hydrogen peroxide-induced apoptosis in HEK 293T cells.

    PubMed

    Huang, Jin; Zhou, Chi; He, Jun; Hu, Zheng; Guan, Wen-Chao; Liu, Sheng-Hong

    2016-06-01

    Hydrogen peroxide (H2O2) and free radicals cause oxidative stress, which induces cellular injuries, metabolic dysfunction, and even cell death in various clinical abnormalities. Fullerene (C60) is critical for scavenging oxygen free radicals originated from cell metabolism, and reduced glutathione (GSH) is another important endogenous antioxidant. In this study, a novel water-soluble reduced glutathione fullerene derivative (C60-GSH) was successfully synthesized, and its beneficial roles in protecting against H2O2-induced oxidative stress and apoptosis in cultured HEK 293T cells were investigated. Fourier Transform infrared spectroscopy and (1)H nuclear magnetic resonance were used to confirm the chemical structure of C60-GSH. Our results demonstrated that C60-GSH prevented the reactive oxygen species (ROS)-mediated cell damage. Additionally, C60-GSH pretreatment significantly attenuated H2O2-induced superoxide dismutase (SOD) consumption and malondialdehyde (MDA) elevation. Furthermore, C60-GSH inhibited intracellular calcium mobilization, and subsequent cell apoptosis via bcl-2/bax-caspase-3 signaling pathway induced by H2O2 stimulation in HEK 293T cells. Importantly, these protective effects of C60-GSH were superior to those of GSH. In conclusion, these results suggested that C60-GSH has potential to protect against H2O2-induced cell apoptosis by scavenging free radicals and maintaining intracellular calcium homeostasis without evident toxicity.

  20. C(60) reduces the flammability of polypropylene nanocomposites by in situ forming a gelled-ball network.

    PubMed

    Song, Ping'an; Zhu, Yan; Tong, Lifang; Fang, Zhengping

    2008-06-01

    The thermal and flame retardancy properties of polypropylene/fullerene (PP/C(60)) nanocomposites were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and cone calorimetry with the C(60) loading varied from 0.5 to 2% by weight. Dispersion of C(60) in the PP matrix was characterized by transmission electron microscopy (TEM) and optical microscopy (OM). TGA and DSC results showed that the presence of C(60) could remarkably enhance the thermal property and cone calorimeter measurements suggested that C(60) could to some extent reduce the flammability of PP, with a significant reduction in peak heat release rate and a much longer time to ignition. Furthermore, the larger the loading level of C(60), the better the flame retardancy property of PP/C(60) nanocomposites. The flame retardation mechanism and corresponding model were proposed with the help of rheological measurements, TEM and x-ray diffraction. C(60) reduced the flammability of PP by trapping free radicals in the gas phase and in situ forming a gelled-ball crosslink network to improve the flame retardancy of PP in the condensed phase. Finally, this suggested mechanism was supported by the results of advanced rheological extended systems (ARES), gel content, infrared spectrum, OM, and atomic force microscopy (AFM) measurements. PMID:21825774

  1. C60 reduces the flammability of polypropylene nanocomposites by in situ forming a gelled-ball network

    NASA Astrophysics Data System (ADS)

    Song, Ping'an; Zhu, Yan; Tong, Lifang; Fang, Zhengping

    2008-06-01

    The thermal and flame retardancy properties of polypropylene/fullerene (PP/C60) nanocomposites were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and cone calorimetry with the C60 loading varied from 0.5 to 2% by weight. Dispersion of C60 in the PP matrix was characterized by transmission electron microscopy (TEM) and optical microscopy (OM). TGA and DSC results showed that the presence of C60 could remarkably enhance the thermal property and cone calorimeter measurements suggested that C60 could to some extent reduce the flammability of PP, with a significant reduction in peak heat release rate and a much longer time to ignition. Furthermore, the larger the loading level of C60, the better the flame retardancy property of PP/C60 nanocomposites. The flame retardation mechanism and corresponding model were proposed with the help of rheological measurements, TEM and x-ray diffraction. C60 reduced the flammability of PP by trapping free radicals in the gas phase and in situ forming a gelled-ball crosslink network to improve the flame retardancy of PP in the condensed phase. Finally, this suggested mechanism was supported by the results of advanced rheological extended systems (ARES), gel content, infrared spectrum, OM, and atomic force microscopy (AFM) measurements.

  2. Protective effect of reduced glutathione C60 derivative against hydrogen peroxide-induced apoptosis in HEK 293T cells.

    PubMed

    Huang, Jin; Zhou, Chi; He, Jun; Hu, Zheng; Guan, Wen-Chao; Liu, Sheng-Hong

    2016-06-01

    Hydrogen peroxide (H2O2) and free radicals cause oxidative stress, which induces cellular injuries, metabolic dysfunction, and even cell death in various clinical abnormalities. Fullerene (C60) is critical for scavenging oxygen free radicals originated from cell metabolism, and reduced glutathione (GSH) is another important endogenous antioxidant. In this study, a novel water-soluble reduced glutathione fullerene derivative (C60-GSH) was successfully synthesized, and its beneficial roles in protecting against H2O2-induced oxidative stress and apoptosis in cultured HEK 293T cells were investigated. Fourier Transform infrared spectroscopy and (1)H nuclear magnetic resonance were used to confirm the chemical structure of C60-GSH. Our results demonstrated that C60-GSH prevented the reactive oxygen species (ROS)-mediated cell damage. Additionally, C60-GSH pretreatment significantly attenuated H2O2-induced superoxide dismutase (SOD) consumption and malondialdehyde (MDA) elevation. Furthermore, C60-GSH inhibited intracellular calcium mobilization, and subsequent cell apoptosis via bcl-2/bax-caspase-3 signaling pathway induced by H2O2 stimulation in HEK 293T cells. Importantly, these protective effects of C60-GSH were superior to those of GSH. In conclusion, these results suggested that C60-GSH has potential to protect against H2O2-induced cell apoptosis by scavenging free radicals and maintaining intracellular calcium homeostasis without evident toxicity. PMID:27376803

  3. Preparation of C60(O)n-ZnO nanocomposite under electric furnace and photocatalytic degradation of organic dyes.

    PubMed

    Cho, Bum Hwi; Oh, Youn Jun; Mun, Sang Mi; Ko, Weon Bae

    2012-07-01

    Zinc oxide (ZnO) nanoparticles were synthesized sonochemically by applying ultrasonic irradiation to a mixed aqueous-alcoholic solution of zinc nitrate with sodium hydroxide at room temperature. The morphology and optical properties of the ZnO nanoparticles were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-vis spectroscopy. The C60(O)n nanoparticles were synthesized by heating a mixture of C60 and 3-chloroperoxybenzoic acid in a benzene solvent under the reflux system. The heated C60(O)n-ZnO nanocomposite was synthesized in an electric furnace at 700 degrees C for two hours. The heated C60(O)n-ZnO nanocomposite was characterized by XRD, SEM, and TEM, and examined as a catalyst in the photocatalytic degradation of organic dyes by UV-vis spectroscopy. The photocatalytic effect of the heated C60(O)n-ZnO nanocomposite was evaluated by a comparison with that of unheated C60(O)n nanoparticles, heated C60(O)n nanoparticles, and unheated C60(O)n-ZnO in organic dyes, such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB) under ultraviolet light at 365 nm.

  4. Comparison of the cytotoxic responses of Escherichia coli (E. coli) AMC 198 to different fullerene suspensions (nC60).

    PubMed

    Dai, Ji; Wang, Chao; Shang, Chii; Graham, Nigel; Chen, Guang-Hao

    2012-04-01

    Fullerenes are set to be produced on an industrial scale in anticipation of their wide applications. This calls for research on their environmental and health impacts. This study investigates and compares the cell toxicity of different aqueous fullerene aggregates. Popular C(60) dispersal methods were used to prepare four types of nC(60) aggregates. These aggregates were tested against the indicator species Escherichia coli (E. coli) AMC 198. With aggregates of around 150 nm in diameter, the THF/nC(60) suspension was very toxic and gave rise to a half maximal effective concentration (EC(50)) of 0.54 mg L(-1) in E. coli. By contrast, the Tol/nC(60) suspension exhibited a cytoprotective role while the Aqu-N(2)/nC(60) and Aqu-O(2)/nC(60) suspensions enhanced the metabolism of E. coli. Although some toxicants, such as THF and THF-peroxide, were introduced into the THF/nC(60) suspension during the dispersion, the toxicity of nC(60) itself cannot be neglected.

  5. Effects of Humic Acid and Sunlight on the Generation and Aggregation State of Aqu/C60 Nanoparticles

    EPA Science Inventory

    Aqueous suspensions of nanoscale C60 aggregates (aqu/C60) were produced by stirring in water with Suwanee River Humic Acid (humic acid) and water from Call’s Creek, a small stream near Athens, GA. Time course experiments were conducted to determine the effects of sunlight and sol...

  6. 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.

  7. Effects of partial hydrogenation on electronic transport properties in C60 molecular devices

    NASA Astrophysics Data System (ADS)

    Chen, L. N.; Cao, C.; Wu, X. Z.; Ma, S. S.; Huang, W. R.; Xu, H.

    2012-12-01

    By using nonequilibrium Green's functions in combination with the density-function theory, we investigate electronic transport properties of molecular devices with pristine and partial hydrogenation. The calculated results show that the electronic transport properties of molecular devices can be modulated by partial hydrogenation. Interestingly, our results exhibit negative differential resistance behavior in the case of the imbalance H-adsorption in C60 molecular devices under low bias. However, negative differential resistance behavior cannot be observed in the case of the balance H-adsorption. A mechanism is proposed for the hydrogenation and negative differential resistance behavior.

  8. Rb NMR study of the electronic properties of Rb 1C 60

    NASA Astrophysics Data System (ADS)

    Brouet, V.; Yoshinari, Y.; Alloul, H.; Forro, L.

    1994-12-01

    87Rb (and 85Rb) NMR spectra in the orthorhombic phase ( (o) phase) of Rb 1C 60 show up broadening, with respect to the high-T cubic phase and to the quenched phase, which signals change of symmetry of the Rb site. The spin lattice relaxation rate follows a linear T dependence in the (o) phase above 100 K, suggesting that this phase is metallic. The increase of 1/T 1T at low T seems to be correlated with the transition seen by E.S.R.

  9. Imaging delocalized electron clouds: photoionization of C(60) in Fourier reciprocal space.

    PubMed

    Rüdel, Andy; Hentges, Rainer; Becker, Uwe; Chakraborty, Himadri S; Madjet, Mohamed E; Rost, Jan M

    2002-09-16

    The dynamics of the photoionization of the two outermost orbitals of C(60) has been studied in the oscillatory regime from threshold to the carbon K edge. We show that geometrical properties of the fullerene electronic hull, such as its diameter and thickness, are contained in the partial photoionization cross sections by examining ratios of partial cross sections as a function of the photon wave number in the Fourier conjugated space. Evaluated in this unconventional manner photoemission data reveal directly the desired spatial information.

  10. Atomic force microscope studies of fullerene films - Highly stable C60 fcc (311) free surfaces

    NASA Technical Reports Server (NTRS)

    Snyder, Eric J.; Tong, William M.; Williams, R. S.; Anz, Samir J.; Anderson, Mark S.

    1991-01-01

    Atomic force microscopy and X-ray diffractometry were used to study 1500 A-thick films of pure C60 grown by sublimation in ultrahigh vacuum onto a CaF2 (111) substrte. Topographs of the films did not reveal the expected close-packed structures, but they showed instead large regions that correspond to a face-centered cubic (311) surface and distortions of this surface. The open (311) structure may have a relatively low free energy because the low packing density contributes to a high entropy of the exposed surface.

  11. Enhanced charge transfer by phenyl groups at a rubrene/C60 interface

    NASA Astrophysics Data System (ADS)

    Mou, Weiwei; Ohmura, Satoshi; Hattori, Shinnosuke; Nomura, Ken-ichi; Shimojo, Fuyuki; Nakano, Aiichiro

    2012-05-01

    Exciton dynamics at an interface between an electron donor, rubrene, and a C60 acceptor is studied by nonadiabatic quantum molecular dynamics simulation. Simulation results reveal an essential role of the phenyl groups in rubrene in increasing the charge-transfer rate by an order-of-magnitude. The atomistic mechanism of the enhanced charge transfer is found to be the amplification of aromatic breathing modes by the phenyl groups, which causes large fluctuations of electronic excitation energies. These findings provide insight into molecular structure design for efficient solar cells, while explaining recent experimental observations.

  12. Enhanced charge transfer by phenyl groups at a rubrene/C60 interface.

    PubMed

    Mou, Weiwei; Ohmura, Satoshi; Hattori, Shinnosuke; Nomura, Ken-ichi; Shimojo, Fuyuki; Nakano, Aiichiro

    2012-05-14

    Exciton dynamics at an interface between an electron donor, rubrene, and a C(60) acceptor is studied by nonadiabatic quantum molecular dynamics simulation. Simulation results reveal an essential role of the phenyl groups in rubrene in increasing the charge-transfer rate by an order-of-magnitude. The atomistic mechanism of the enhanced charge transfer is found to be the amplification of aromatic breathing modes by the phenyl groups, which causes large fluctuations of electronic excitation energies. These findings provide insight into molecular structure design for efficient solar cells, while explaining recent experimental observations. PMID:22583307

  13. Picosecond to millisecond photoexcitation dynamics in blends of C 60 with poly( p-phenylene vinylene) polymers

    NASA Astrophysics Data System (ADS)

    Frolov, S. V.; Lane, P. A.; Ozaki, M.; Yoshino, K.; Vardeny, Z. V.

    1998-04-01

    We compare photoexcitation dynamics in films of pristine and C 60-mixed 2,5-dioctyloxy poly( p-phenylene vinylene) (DOO-PPV) using ps transient and cw photoinduced absorption (PA), and PA-detected magnetic resonance (PADMR). We conclude that C 60 doping is relatively inefficient in DOO-PPV. Consequently, the instantaneous exciton photogeneration yield remains high (close to 1) even at high C 60 concentrations. However, as the C 60 concentration increases up to 10 molar percent, the stimulated emission lifetime and cw photoluminescence intensity decrease together by about an order of magnitude due to dissociation of the singlet excitons at C 60 related defect centers into intrachain polaron pairs, which were identified by PADMR.

  14. Effect of geometrical orientation on the charge-transfer energetics of supramolecular (tetraphenyl)-porphyrin/C60 dyads

    NASA Astrophysics Data System (ADS)

    Olguin, Marco; Zope, Rajendra R.; Baruah, Tunna

    2013-02-01

    The charge transfer (CT) excited state energies of donor-acceptor (D/A) pairs determine the achievable open-circuit voltage of D/A-based organic solar cell devices. Changes in the relative orientation of donor-acceptor pairs at the interface influence the frontier orbital energy levels, which impacts the dissociation of bound excitons at the D/A-interface. We examine the effect of relative orientation on CT excited state energies of porphyrin-fullerene dyads. The donors studied are base- and Zn-tetraphenyl porphyrin coupled to C60 as the acceptor molecule in an end-on configuration. We compare the energetics of a few low-lying CT states for the end-on geometry to our previously calculated CT energetics of a co-facial orientation. The calculated CT excitation energies are larger for the end-on orientation in comparison to the co-facial structure by about 0.7 eV, which primarily occurs due to a decrease in exciton binding energy in going from the co-facial to the end-on orientation. Furthermore, changes in relative donor-acceptor orientation have a larger impact on the CT energies than changes in donor-acceptor distance.

  15. In Silico Olefin Metathesis with Ru-Based Catalysts Containing N-Heterocyclic Carbenes Bearing C60 Fullerenes.

    PubMed

    Martínez, Juan Pablo; Vummaleti, Sai Vikrama Chaitanya; Falivene, Laura; Nolan, Steven P; Cavallo, Luigi; Solà, Miquel; Poater, Albert

    2016-05-01

    Density functional theory calculations have been used to explore the potential of Ru-based complexes with 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (SIMes) ligand backbone (A) being modified in silico by the insertion of a C60 molecule (B and C), as olefin metathesis catalysts. To this end, we investigated the olefin metathesis reaction catalyzed by complexes A, B, and C using ethylene as the substrate, focusing mainly on the thermodynamic stability of all possible reaction intermediates. Our results suggest that complex B bearing an electron-withdrawing N-heterocyclic carbene improves the performance of unannulated complex A. The efficiency of complex B is only surpassed by complex A when the backbone of the N-heterocyclic carbene of complex A is substituted by two amino groups. The particular performance of complexes B and C has to be attributed to electronic factors, that is, the electronic-donating capacity of modified SIMes ligand rather than steric effects, because the latter are predicted to be almost identical for complexes B and C when compared to those of A. Overall, this study indicates that such Ru-based complexes B and C might have the potential to be effective olefin metathesis catalysts.

  16. Effect of geometrical orientation on the charge-transfer energetics of supramolecular (tetraphenyl)-porphyrin∕C60 dyads.

    PubMed

    Olguin, Marco; Zope, Rajendra R; Baruah, Tunna

    2013-02-21

    The charge transfer (CT) excited state energies of donor-acceptor (D∕A) pairs determine the achievable open-circuit voltage of D∕A-based organic solar cell devices. Changes in the relative orientation of donor-acceptor pairs at the interface influence the frontier orbital energy levels, which impacts the dissociation of bound excitons at the D∕A-interface. We examine the effect of relative orientation on CT excited state energies of porphyrin-fullerene dyads. The donors studied are base- and Zn-tetraphenyl porphyrin coupled to C60 as the acceptor molecule in an end-on configuration. We compare the energetics of a few low-lying CT states for the end-on geometry to our previously calculated CT energetics of a co-facial orientation. The calculated CT excitation energies are larger for the end-on orientation in comparison to the co-facial structure by about 0.7 eV, which primarily occurs due to a decrease in exciton binding energy in going from the co-facial to the end-on orientation. Furthermore, changes in relative donor-acceptor orientation have a larger impact on the CT energies than changes in donor-acceptor distance.

  17. In Silico Olefin Metathesis with Ru-Based Catalysts Containing N-Heterocyclic Carbenes Bearing C60 Fullerenes.

    PubMed

    Martínez, Juan Pablo; Vummaleti, Sai Vikrama Chaitanya; Falivene, Laura; Nolan, Steven P; Cavallo, Luigi; Solà, Miquel; Poater, Albert

    2016-05-01

    Density functional theory calculations have been used to explore the potential of Ru-based complexes with 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (SIMes) ligand backbone (A) being modified in silico by the insertion of a C60 molecule (B and C), as olefin metathesis catalysts. To this end, we investigated the olefin metathesis reaction catalyzed by complexes A, B, and C using ethylene as the substrate, focusing mainly on the thermodynamic stability of all possible reaction intermediates. Our results suggest that complex B bearing an electron-withdrawing N-heterocyclic carbene improves the performance of unannulated complex A. The efficiency of complex B is only surpassed by complex A when the backbone of the N-heterocyclic carbene of complex A is substituted by two amino groups. The particular performance of complexes B and C has to be attributed to electronic factors, that is, the electronic-donating capacity of modified SIMes ligand rather than steric effects, because the latter are predicted to be almost identical for complexes B and C when compared to those of A. Overall, this study indicates that such Ru-based complexes B and C might have the potential to be effective olefin metathesis catalysts. PMID:27059290

  18. C60 Exposure Augments Cardiac Ischemia/Reperfusion Injury and Coronary Artery Contraction in Sprague Dawley Rats

    PubMed Central

    Holland, Nathan A.; Vidanapathirana, Achini K.; Pitzer, Joshua E.; Han, Li; Sumner, Susan J.; Lewin, Anita H.; Fennell, Timothy R.; Lust, Robert M.; Brown, Jared M.; Wingard, Christopher J.

    2014-01-01

    The potential uses of engineered C60 fullerene (C60) have expanded in recent decades to include industrial and biomedical applications. Based on clinical findings associated with particulate matter exposure and our data with multi-walled carbon nanotubes, we hypothesized that ischemia/reperfusion (I/R) injury and pharmacological responses in isolated coronary arteries would depend upon the route of exposure and gender in rats instilled with C60. Male and female Sprague Dawley rats were used to test this hypothesis by surgical induction of cardiac I/R injury in situ 24 h after intratracheal (IT) or intravenous (IV) instillation of 28 μg of C60 formulated in polyvinylpyrrolidone (PVP) or PVP vehicle. Serum was collected for quantification of various cytokines. Coronary artery segments were isolated for assessment of vasoactive pharmacology via wire myography. Both IV and IT exposure to C60 resulted in expansion of myocardial infarction in male and female rats following I/R injury. Serum-collected post-I/R showed elevated concentrations of interleukin-6 and monocyte chemotactic protein-1 in male rats exposed to IV C60. Coronary arteries isolated from male rats exposed to IT C60 demonstrated augmented vasocontraction in response to endothelin-1 that was attenuated with Indomethacin. IV C60 exposure resulted in impaired acetylcholine relaxation in male rats and IT C60 exposure resulted in depressed vasorelaxation in response to sodium nitroprusside in female rats. Based on these data, we conclude that IT and IV exposure to C60 results in unique cardiovascular consequences that may favor heightened coronary resistance and myocardial susceptibility to I/R injury. PMID:24431213

  19. An electrogenerated chemiluminescence sensor based on gold nanoparticles@C60 hybrid for the determination of phenolic compounds.

    PubMed

    Lu, Qiyi; Hu, Hongxiang; Wu, Yuanya; Chen, Shihong; Yuan, Dehua; Yuan, Ruo

    2014-10-15

    This paper described a novel strategy for the construction of an electrogenerated chemiluminescence (ECL) sensor based on gold nanoparticles@C60 (AuNPs@C60) hybrid for detecting phenolic compounds. First, C60 was functionalized with l-cysteine. Subsequently, with C60 as the core, gold nanoparticles (AuNPs) are synthesized and grown through an in situ reduction method in the presence of ascorbic acid (AA). The resulted flowerlike AuNPs@C60 nanoparticles were modified onto the glassy carbon electrode to achieve the sensor (AuNPs@C60/GCE). Here, l-cysteine not only can improve the biocompatibility and hydrophilicity of C60 but also can enhance the electrogenerated chemiluminescence (ECL) of peroxydisulfate system. Furthermore, both AuNPs and C60 are also beneficial to the ECL of the peroxydisulfate system. Due to the combination of l-cysteine, AuNPs and C60, the proposed ECL sensor exhibited an excellent analytical performance. Under an optimum condition, the ECL intensity increased linearly with phenolic compounds. The linear ranges of 6.2 × 10(-8)-1.2 × 10(-4)M, 5.0 × 10(-8)-1.1 × 10(-4)M and 5.0 × 10(-8)-1.1 × 10(-4)M were obtained for catechol (CC), hydroquinone (HQ) and p-cresol (PC), respectively, and the detection limits were 2.1 × 10(-8)M, 1.5 × 10(-8)M and 1.7 × 10(-8)M, respectively. The AuNPs@C60 hybrid might hold a new opportunity to develop an ECL sensor. PMID:24836015

  20. Valence photoionization of small alkaline earth atoms endohedrally confined in C60

    NASA Astrophysics Data System (ADS)

    Javani, M. H.; McCreary, M. R.; Patel, A. B.; Madjet, M. E.; Chakraborty, H. S.; Manson, S. T.

    2012-07-01

    A theoretical study of photoionization from the outermost orbitals of Be, Mg and Ca atoms endohedrally confined in C60 is reported. The fullerene ion core, comprised of sixty C4+, is smudged into a continuous jellium charge distribution, while the delocalized cloud of carbon valence electrons plus the encaged atom are treated in the time-dependent local density approximation (TDLDA). Systematic evolution of the mixing of outer atomic level with states of the C60 valence band is found along the sequence. This is found to influence the plasmonic enhancement of atomic photoionization at low energies and the geometry-revealing confinement oscillations at high energies in significantly different ways: (a) the extent of enhancement is mainly determined by the strength of atomic ionization, giving the strongest enhancement for Be even though Ca suffers the largest mixing. But (b) strongest collateral oscillations are uncovered for Ca, since, relative to Be and Mg, the mixing causes the highest photoelectron production at confining boundaries of Ca. The study paints the first comparative picture of the atomic valence photospectra for alkaline earth metallofullerenes in a dynamical many-electron framework.

  1. Disorder effect on conductance in a doped C60 molecular bridge

    NASA Astrophysics Data System (ADS)

    Shokri, Aliasghar

    2013-03-01

    In this work, we study electrical conductance in a C60 molecular nanobridge with randomly point dopants sandwiched between two (5,5) carbon nanotubes (CNTs) in two cases with opened end and closed end. Two different ways of coupling C60 fullerene through one and five carbon atoms to the uncap- and cap-edges are considered in each case. Our calculations are based on the Green's function technique in the tight-binding approximation. The CNT surface self-energy is also obtained, analytically. The effects of contacts, various strengths of random disorder, cage type, and the bond dimerization on the conductance are investigated. Our results indicate that the appearance of conductance resonances is a manifestation of resonant states of CNT caps, which lie within the molecular HOMO-LUMO gap and consequently they change by disorder concentration. By controlling the disorder concentration, bond dimerization, and contact geometries, this kind of system can explain the extended states from the localized states. The numerical results can serve as a base for developments in designing nanoelectronic devices.

  2. The strength of electron electron correlation in Cs3C60

    PubMed Central

    Baldassarre, L.; Perucchi, A.; Mitrano, M.; Nicoletti, D.; Marini, C.; Pontiroli, D.; Mazzani, M.; Aramini, M.; Riccó, M.; Giovannetti, G.; Capone, M.; Lupi, S.

    2015-01-01

    Cs3C60 is an antiferromagnetic insulator that under pressure (P) becomes metallic and superconducting below Tc = 38 K. The superconducting dome present in the T − P phase diagram close to a magnetic state reminds what found in superconducting cuprates and pnictides, strongly suggesting that superconductivity is not of the conventional Bardeen-Cooper-Schrieffer (BCS) type We investigate the insulator to metal transition induced by pressure in Cs3C60 by means of infrared spectroscopy supplemented by Dynamical Mean-Field Theory calculations. The insulating compound is driven towards a metallic-like behaviour, while strong correlations survive in the investigated pressure range. The metallization process is accompanied by an enhancement of the Jahn-Teller effect. This shows that electronic correlations are crucial in determining the insulating behaviour at ambient pressure and the bad metallic nature for increasing pressure. On the other hand, the relevance of the Jahn-Teller coupling in the metallic state confirms that phonon coupling survives in the presence of strong correlations. PMID:26468959

  3. Giant THz photoconductivity and possible non-equilibrium superconductivity in metallic K3C60

    PubMed Central

    Mitrano, M.; Cantaluppi, A.; Nicoletti, D.; Kaiser, S.; Perucchi, A.; Lupi, S.; Di Pietro, P.; Pontiroli, D.; Riccò, M.; Clark, S. R.; Jaksch, D.; Cavalleri, A.

    2015-01-01

    The non-equilibrium control of emergent phenomena in solids is an important research frontier, encompassing effects like the optical enhancement of superconductivity 1 . Recently, nonlinear excitation 2 , 3 of certain phonons in bilayer cuprates was shown to induce superconducting-like optical properties at temperatures far above Tc 4,5,6. This effect was accompanied by the disruption of competing charge-density-wave correlations7,8, which explained some but not all of the experimental results. Here, we report a similar phenomenon in a very different compound. By exciting metallic K3C60 with mid-infrared optical pulses, we induce a large increase in carrier mobility, accompanied by the opening of a gap in the optical conductivity. Strikingly, these same signatures are observed at equilibrium when cooling metallic K3C60 below the superconducting transition temperature (Tc = 20 K). Although optical techniques alone cannot unequivocally identify non-equilibrium high-temperature superconductivity, we propose this scenario as a possible explanation of our results. PMID:26855424

  4. Strong-field effects in the photoemission spectrum of the C60 fullerene

    NASA Astrophysics Data System (ADS)

    Gao, C.-Z.; Dinh, P. M.; Klüpfel, P.; Meier, C.; Reinhard, P.-G.; Suraud, E.

    2016-02-01

    Considering C60 as a model system for describing field emission from the extremity of a carbon nanotip, we explore electron emission from this fullerene excited by an intense, near-infrared, few-cycle laser pulse (1013- 1014W/cm2 , 912 nm, 8-cycle). To this end, we use time-dependent density functional theory augmented by a self-interaction correction. The ionic background of C60 is described by a soft jellium model. Particular attention is paid to the high-energy electrons. Comparing the spectra at different emission angles, we find that, as a major result of this study, the photoelectrons are strongly peaked along the laser polarization axis forming a highly collimated electron beam in the forward direction, especially for the high-energy electrons. Moreover, the high-energy plateau cutoff found in the simulations agrees well with estimates from the classical three-step model. We also investigate the buildup of the high-energy part of a photoelectron spectrum by a time-resolved analysis. In particular, the modulation on the plateau can be interpreted as contributions from intracycle and intercycle interferences.

  5. Understanding the Interface Dipole of Copper Phthalocyanine (CuPc)/C60: Theory and Experiment.

    PubMed

    Sai, Na; Gearba, Raluca; Dolocan, Andrei; Tritsch, John R; Chan, Wai-Lun; Chelikowsky, James R; Leung, Kevin; Zhu, Xiaoyang

    2012-08-16

    Interface dipole determines the electronic energy alignment in donor/acceptor interfaces and plays an important role in organic photovoltaics. Here we present a study combining first principles density functional theory (DFT) with ultraviolet photoemission spectroscopy (UPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) to investigate the interface dipole, energy level alignment, and structural properties at the interface between CuPc and C60. DFT finds a sizable interface dipole for the face-on orientation, in quantitative agreement with the UPS measurement, and rules out charge transfer as the origin of the interface dipole. Using TOF-SIMS, we show that the interfacial morphology for the bilayer CuPc/C60 film is characterized by molecular intermixing, containing both the face-on and the edge-on orientation. The complementary experimental and theoretical results provide both insight into the origin of the interface dipole and direct evidence for the effect of interfacial morphology on the interface dipole.

  6. Modulating charge-transfer interactions in topologically different porphyrin-C60 dyads.

    PubMed

    Guldi, Dirk M; Hirsch, Andreas; Scheloske, Michael; Dietel, Elke; Troisi, Alessandro; Zerbetto, Francesco; Prato, Maurizio

    2003-10-17

    Control over the interchromophore separation, their angular relationship, and the spatial overlap of their electronic clouds in several ZnP-C(60) dyads (ZnP=zinc porphyrin) is used to modulate the rates of intramolecular electron transfer. For the first time, a detailed analysis of the charge transfer absorption and emission spectra, time-dependent spectroscopic measurements, and molecular dynamics simulations prove quantitatively that the same two moieties can produce widely different electron-transfer regimes. This investigation also shows that the combination of ZnP and C(60) consistently produces charge recombination in the inverted Marcus region, with reorganization energies that are remarkably low, regardless of the solvent polarity. The time constants of electron transfer range from the mus to the ps regime, the electronic couplings from a few tens to several hundreds of cm(-1), and the reorganization energies remain below 0.54 eV and can be as low as 0.16 eV.

  7. 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.

  8. Comprehensive studies of response characteristics of organic photodetectors based on rubrene and C60

    NASA Astrophysics Data System (ADS)

    Yang, Dezhi; Xu, Kai; Zhou, Xiaokang; Wang, Yanping; Ma, Dongge

    2014-06-01

    We studied the transient response characteristics of organic photodetectors composing of high mobility materials of rubrene and C60, respectively, as donor and acceptor. It was found that the response speed was limited by the delay time of both exciton diffusion and transit, and an anomalous phenomenon that the bandwidth decreases as the reverse bias increases was found for the first time. The investigation of frequency dependence at different device structures and light excitations demonstrated that the light absorption of rubrene prevents the photodetector from obtaining a fast response. With the help of magnetic field effect study, it was clearly elucidated that the slow diffusion time of the long lifetime triplet excitons generated from singlet fission in rubrene limited the bandwidth of the device. Moreover, the simulation of the response of photodetector under transient and steady state by exciton transport-diffusion equation showed that the exciton dissociation efficiency in rubrene increases more quickly than that in C60, which should account for the negative dependence of bandwidth on the reverse bias in rubrene-based device.

  9. Effects of C60 fullerene nanoparticles on soil bacteria and protozoans.

    PubMed

    Johansen, Anders; Pedersen, Anette L; Jensen, Keld A; Karlson, Ulrich; Hansen, Bjarne M; Scott-Fordsmand, Janeck J; Winding, Anne

    2008-09-01

    Nanotechnology should produce numerous new materials in the coming years. Because of the novel design of nanomaterials with new physicochemical characteristics, their potential adverse impact on the environment and human health must be addressed. In the present study, agglomerates of pristine C60 fullerenes (50 nm to microm-size) were applied to soil at 0, 5, 25, and 50 mg/kg dry soil to assess their effect on the soil microbiota by measuring total respiration; biomass, number, and diversity of bacteria; and total number and diversity of protozoans during 14 d. Respiration and microbial biomass were unaffected by the fullerenes at any time, whereas the number of fast-growing bacteria was decreased by three- to fourfold just after incorporation of the nanomaterial. Protozoans seemed not to be very sensitive to C60, because their number decreased only slightly in the beginning of the experiment. With polymerase chain reaction and denaturing gradient gel electrophoresis analysis of eubacteria and kinetoplastids from the soil, however, a difference between the fullerene treatments and nonamended controls was demonstrated. The fullerenes did not induce more than 20 to 30% of relative dissimilarity (with both bacteria and protozoans) between treatments, but this effect was persistent throughout the experiment. It therefore is recommended that fullerene nanomaterial not be spread deliberately in the environment and that their ecotoxicology be further clarified. PMID:19086316

  10. Regioselective intramolecular Pauson-Khand reactions of C60: an electrochemical study and theoretical underpinning.

    PubMed

    Martín, Nazario; Altable, Margarita; Filippone, Salvatore; Martín-Domenech, Angel; Poater, Albert; Solà, Miquel

    2005-04-22

    Suitably functionalized fulleropyrrolidines endowed with one or two propargyl groups at the C-2 position of the pyrrolidine ring (1,6-enynes) react efficiently and regioselectively with [Co2(CO)8] to afford the respective Pauson-Khand products with an unprecedented three (5 a-d, 7, and 24) or five (25) pentagonal rings, respectively, fused onto the fullerene sphere. Fulleropyrrolidines with 1,7-, 1,9-, 1,10-, or 1,11-enyne moieties do not undergo the PK reaction and, instead, the intermediate dicobalt complexes formed with the alkynyl group are isolated in quantitative yields. These differences in reactivity have been studied by DFT calculations with a generalized gradient approximation (GGA) functional and several important energy and structural differences were found for the intermediates formed by the interaction between the coordinatively unsaturated Co atom and the pi system of C60 in 1,6- and 1,7-enynes. The different lengths of the alkyne chains are responsible for the observed reactivities. Cyclic voltammetry reveals that the presence of the cyclopentenone's carbonyl group connected directly to the C60 core results in PK compounds with remarkable electron-accepting ability. PMID:15729679

  11. Extraction and HPLC- UV Analysis of C60, C70, and [6,6]-phenyl C61-butyric acid methyl ester in Synthetic and Natural Waters

    EPA Science Inventory

    Studies have shown that C60 fullerene can form stable colloidal suspensions in water that result in C60 aqueous concentrations many orders of magnitude above C60's aqueous solubility; however, quantitative methods for the analysis of C60 and other fullerenes in environmental medi...

  12. PVP formulated Fullerene (C60) increases Rho-kinase dependent Vascular Tissue Contractility in Pregnant Sprague Dawley Rats

    PubMed Central

    Vidanapathirana, Achini K.; Thompson, Leslie C.; Mann, Erin. E.; Odom, Jillian T.; Holland, Nathan A.; Sumner, Susan J.; Han, Li; Lewin, Anita H.; Fennell, Timothy R.; Brown, Jared M.; Wingard, Christopher J.

    2014-01-01

    Pregnancy is a unique physiological state, in which C60 fullerene is reported to be distributed in both maternal and fetal tissues. Tissue distribution of C60 differs between pregnant and non-pregnant states, presumably due to functional changes in vasculature during pregnancy. We hypothesized that, polyvinylpyrorrolidone (PVP) formulated C60 (C60/PVP) increases vascular tissue contractility during pregnancy by increasing Rho-kinase activity. C60/PVP was administered intravenously to pregnant and non-pregnant female Sprague Dawley rats. Vascular responses were assessed using wire myography 24 hours post-exposure. Increased stress generation was observed in uterine artery, thoracic aorta and umbilical vein. Rho-Rho-kinase mediated force maintenance was increased in arterial segments from C60/PVP exposed pregnant rats when compared to PVP exposed rats. Our findings suggest that intravenous exposure to C60/PVP during pregnancy increases vascular tissue contractility of the uterine artery through elements of Rho-Rho-kinase signaling during late stages of pregnancy. PMID:25088243

  13. Synthesis of gold nano-wire and nano-dumbbell shaped colloids and AuC60 nano-clusters

    NASA Astrophysics Data System (ADS)

    Landon, Preston B.; Jarvis, Brandon C.; Gilleland, Cody L.; Renfro, Tim; Gutierrez, Jose; Synowczynski, Jennifer; Hirsch, Samuel G.; Glosser, Robert

    2005-08-01

    A technique for the fabrication of colloidal gold nano-wire and nano-dumbbell shaped particles using carbon nanotubes and rod shaped viruses as templates is described. The gold (Au) encapsulation process was accomplished by the precipitation of gold chloride from aqueous solutions. When this process was conducted in the presence of hydroxylated C60, small pieces of phase-separated composites of AuC60 appeared to have formed. These nano-clusters may turn out to be large noble metal analogs of the alkali metal fullerides with the smallest geometrically possible Au aggregate consisting of 55 gold atoms. The existence of noble metal fullerene composites has been previously theorized. The alkali metal fullerides are examples of phase separated solids and have exhibited superconductivity with temperatures as high 33K. The mechanism required for the binding energy between C60 and gold has been observed to exist between C60 and many of the mirror metals (Al, Ag, Au, Cu, Ni). This binding energy is a charge transfer from the metal Fermi level into the C60 LUMO. If this bonding energy, is greater than the metals coagulation energy an Au/C60 size terminated mechanism during the formation of the gold aggregates by the adhesion of C60 to the surface is energetically favorable.

  14. Adsorbate-induced reconstruction by C60 on close-packed metal surfaces: Mechanism for different types of reconstruction

    NASA Astrophysics Data System (ADS)

    Shi, Xing-Qiang; van Hove, Michel A.; Zhang, Rui-Qin

    2012-02-01

    Recent studies reveal that reconstruction of close-packed metal surfaces induced by C60 adsorption is the rule rather than the exception. Two types of reconstruction are reported for C60 on different surfaces: (1) C60 sinks into a 7-atom hole, such as on Cu(111); and (2) C60 sits over a 1-atom hole, such as on Ag(111) and Pt(111). An explanation for the preferred reconstruction type for different metals has been lacking. Here, we propose a criterion that predicts which reconstruction type should be expected: Namely, the formation of a 1- or 7-atom hole is determined only by the substrate geometric structure, including the surface lattice constant and the interlayer spacing; remarkably, the reconstruction type appears not to depend on the substrate electronic structure. Our intuitive geometrical explanation is validated by comparative first-principles calculations of the energetics of C60 on Cu(111), Ru(0001), Pt(111), and Ag(111) surfaces, listed here with increasing surface lattice constant. This provides a uniform explanation for the different reconstruction types that are observed experimentally for C60 on different close-packed metal surfaces. Moreover, our results provide a better explanation for the decomposition behavior of C60 on Ru(0001).

  15. [Effect of Natural Organic Matter and Electrolytes on the Aggregation of C60 Nanoparticles in Aquatic Systems].

    PubMed

    Fang, Hua; Jing, Jie; Yu, Jiang-hua; Wang, Yu-ting

    2015-10-01

    The ettect of natural organic matter (NOM) and electrolytes on the aggregation of G60 nanoparticles in aquatic systems was studied by using dynamic light scattering. The results showed that the concentration of C60 stable suspension prepared by toluene solvent-exchange method was about 20 mg x L(-1). The C60 nanoparticles in the suspension showed a high zeta potential and particle diameter was around 120 nm. Addition of simple electrolytes induced aggregation of C60 nanoparticles through acompressing electric double layer, which was consistent with the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal stability. The critical coagulation concentration (CCC) values of MgCl2 and CaCl2 were 9.6 and 6.7 mmol x L(-1). In presence of humic acid, the addition of NaCl and MgCl2 reduced the attachment efficiency and aggregation rate of C60 and increased CCCs. Humic acid enhanced the stability of C60 in water due to steric repulsion. However, the complexation reaction between Ca2+ and humic acid caused adsorption bridging with C60, which increased the aggregation rate and led to enhanced aggregation. This was identified as the primary mechanism of such enhanced aggregation behaviour. The aggregation and dispersion of C60 in water was influenced by the characteristics of organic matters, electrolyte species and other complex factors.

  16. Molecular self-healing mechanisms between C60-fullerene and anthracene unveiled by Raman and two-dimensional correlation spectroscopy.

    PubMed

    Geitner, R; Kötteritzsch, J; Siegmann, M; Fritzsch, R; Bocklitz, T W; Hager, M D; Schubert, U S; Gräfe, S; Dietzek, B; Schmitt, M; Popp, J

    2016-07-21

    The self-healing polymer P(LMA-co-MeAMMA) crosslinked with C60-fullerene has been studied by FT-Raman spectroscopy in combination with two-dimensional (2D) correlation analysis and density functional theory calculations. To unveil the molecular changes during the self-healing process mediated by the Diels-Alder equilibrium between 10-methyl-9-anthracenyl groups and C60-fullerene different anthracene-C60-fullerene adducts have been synthesized and characterized by time-, concentration- and temperature-dependent FT-Raman measurements. The self-healing process could be monitored via the C60-fullerene vibrations at 270, 432 and 1469 cm(-1). Furthermore, the detailed analysis of the concentration-dependent FT-Raman spectra point towards the formation of anthracene-C60-fullerene adducts with an unusual high amount of anthracene bound to C60-fullerene in the polymer film, while the 2D correlation analysis of the temperature-dependent Raman spectra suggests a stepwise dissociation of anthracene-C60-fullerene adducts, which are responsible for the self-healing of the polymer. PMID:27327116

  17. Simple Formation of C60 and C60-Ferrocene Conjugated Monolayers Anchored onto Silicon Oxide with Five Carboxylic Acids and Their Transistor Applications

    SciTech Connect

    Y Itoh; B Kim; R Gearba; N Tremblay; R Pindak; Y Matsuo; E Nakamura; C Nuckolls

    2011-12-31

    C{sub 60} and C{sub 60}-ferrocene conjugated molecule bearing five carboxylic acids successfully anchor onto a silicon oxide surface as a monolayer through a simple method of simply dipping an amino-terminated surface into the solution of the C{sub 60} derivatives. The monolayer structure was characterized by UV-vis spectroscopy, X-ray reflectivity, X-ray photoelectron spectroscopy, and IR spectroscopy to reveal that the molecules are standing presenting its C{sub 60} spherical face at the surface. The electronic effect of the C{sub 60} monolayer and the ferrocene-functionalized C{sub 60} monolayer in OFET devices was investigated. When an n-type OFET was fabricated on the ferrocene functionalized monolayer, we see an enhancement in the mobility. When a p-type OFET was made the ferrocene-functionalized C{sub 60} monolayer showed a lowering of the carrier mobility.

  18. Fabrication of C60 Tri-Diethyl Malonate Membrane via an Electrospinning Method and Its Antibacterial Property.

    PubMed

    Li, Hui; Chen, Shou; Peng, Xiaohua; Sun, Jiangning; Shu, Chunying; Jiang, Li; Wang, Chunru

    2016-03-01

    A homogeneous C60 tri-diethyl malonate membrane was fabricated by a facile electro-spinning method. Comprehensive characterizations of its assembling structure, such as SEM, TEM, TGA, UV-vis, and FTIR, were carried out. Different fullerene derivatives show different assembling characters during the electrospining process. Notably, C60 tri-diethyl malonate with close-knite structures can form a stable structure after removing the assistant polymer of PVP. The antibacterial experiments of C60 tri-diethyl malonate membrane were performed, and the results revealed that this membrane owns excellent antibacterial activity.

  19. Fabrication of C60 Tri-Diethyl Malonate Membrane via an Electrospinning Method and Its Antibacterial Property.

    PubMed

    Li, Hui; Chen, Shou; Peng, Xiaohua; Sun, Jiangning; Shu, Chunying; Jiang, Li; Wang, Chunru

    2016-03-01

    A homogeneous C60 tri-diethyl malonate membrane was fabricated by a facile electro-spinning method. Comprehensive characterizations of its assembling structure, such as SEM, TEM, TGA, UV-vis, and FTIR, were carried out. Different fullerene derivatives show different assembling characters during the electrospining process. Notably, C60 tri-diethyl malonate with close-knite structures can form a stable structure after removing the assistant polymer of PVP. The antibacterial experiments of C60 tri-diethyl malonate membrane were performed, and the results revealed that this membrane owns excellent antibacterial activity. PMID:27455662

  20. Photosynthetic antenna-reaction center mimicry with a covalently linked monostyryl boron-dipyrromethene-aza-boron-dipyrromethene-C60 triad.

    PubMed

    Shi, Wen-Jing; El-Khouly, Mohamed E; Ohkubo, Kei; Fukuzumi, Shunichi; Ng, Dennis K P

    2013-08-19

    An efficient functional mimic of the photosynthetic antenna-reaction center has been designed and synthesized. The model contains a near-infrared-absorbing aza-boron-dipyrromethene (ADP) that is connected to a monostyryl boron-dipyrromethene (BDP) by a click reaction and to a fullerene (C60 ) using the Prato reaction. The intramolecular photoinduced energy and electron-transfer processes of this triad as well as the corresponding dyads BDP-ADP and ADP-C60 have been studied with steady-state and time-resolved absorption and fluorescence spectroscopic methods in benzonitrile. Upon excitation, the BDP moiety of the triad is significantly quenched due to energy transfer to the ADP core, which subsequently transfers an electron to the fullerene unit. Cyclic and differential pulse voltammetric studies have revealed the redox states of the components, which allow estimation of the energies of the charge-separated states. Such calculations show that electron transfer from the singlet excited ADP ((1) ADP*) to C60 yielding ADP(.+) -C60 (.-) is energetically favorable. By using femtosecond laser flash photolysis, concrete evidence has been obtained for the occurrence of energy transfer from (1) BDP* to ADP in the dyad BDP-ADP and electron transfer from (1) ADP* to C60 in the dyad ADP-C60 . Sequential energy and electron transfer have also been clearly observed in the triad BDP-ADP-C60 . By monitoring the rise of ADP emission, it has been found that the rate of energy transfer is fast (≈10(11)  s(-1) ). The dynamics of electron transfer through (1) ADP* has also been studied by monitoring the formation of C60 radical anion at 1000 nm. A fast charge-separation process from (1) ADP* to C60 has been detected, which gives the relatively long-lived BDP-ADP(.+) C60 (.-) with a lifetime of 1.47 ns. As shown by nanosecond transient absorption measurements, the charge-separated state decays slowly to populate mainly the triplet state of ADP before returning to the ground state

  1. Interaction and Protection Mechanism between Li@C60 and Nucleic Acid Bases (NABs): Performance of PM6-DH2 on Noncovalent Interaction of NABs-Li@C60

    PubMed Central

    Sun, Wenming; Bu, Yuxiang; Wang, Yixuan

    2011-01-01

    To discuss the protection mechanism of DNA from radiation as well as assess the performance of PM6-DH2 on noncovalent interactions, the interaction of four nucleic acid bases (NABs) such as adenine (A), cytosine (C), guanine (G), and thymine (T), with Li@C60 was extensively investigated with the-state-of-art theoretical methods describing non-covalent systems, like M06-2x, PBE-D, and PM6-DH2 methods. In the gas phase, the binding strength of NABs to Li@C60 from M06-2x decreases in the sequence, G>C>A>T. As dispersion was explicitly included, PBE-D relatively enhances the binding of A and T and corrects the sequence to, G>A>C~T. PM6-DH2 predicted similar binding energies to those from PBE-D within 0.5kcal/mol and the same binding sequence, suggesting that the PM6-DH2 method is promising for nano-scale systems. In the aqueous solution, binding of NABs-Li@C60 is considerably decreased, and the M06-2X and PM6-D methods yield a different sequence from the gas phase, G>A>T>C. The encapsulation of Li atom results in a lower IP for Li@C60 than those of NABs, and the dominant localization of single-occupied molecular orbital on Li@C60 moiety of the complexes NABs-Li@C60 further indicates that an electron would be ejected from Li@C60 upon radiation and Li@C60 is therefore able to protect DNA bases from radiation. In addition, it was revealed that Li prefers coordination with the hexagonal ring at Li@C60, which clarifies the existing controversy in this respect. Finally, Yang’s reduced density gradient approach clearly shows that the weak and strong noncovalent interaction regions in the complexes, NABs-Li@C60 and (NABs-Li@C60)+. PMID:22170247

  2. Effect of Natural Organic Matter (NOM) on Properties and Mobility of Aqueous Fullerene Nanoparticles (nC60)

    NASA Astrophysics Data System (ADS)

    Xie, B.; Li, Q.

    2007-12-01

    C60 fullerene and its derivatives have been used in a number of consumer products and the predicted industrial- scale production of fullerene reaches tons per year. Aqueous fullerene nanoparticles (nC60) could be formed through direct contact of fullerene powder with water or through organic solvent exchange. Existing toxicity data of nC60 indicate that industrial-scale production of fullerene poses a potential threat to the environment. There is a need to evaluate the fate and transport of nC60 in the aqueous environment and its subsequent impact on the bio- and eco- systems. Our study aims to determine the effect of natural organic matter (NOM) on the nC60 entry pathway, physicochemical properties, deposition and mobility in the aqueous phase. Experimental conditions cover those typical of natural waters. Stable nC60 suspensions formed under four different conditions in the presence and absence of two major NOM components, humic acid (HA) and fulvic acid (FA), were thoroughly characterized for particle size, morphology, electrophoretic mobility, and UV absorbance. nC60 deposition experiments were carried out in parallel cross-flow chambers monitored by quartz crystal microbalance (QCM) and the nC60 mass deposition kinetics was studied in the absence and presence of NOM. Our study found that the size, structure and surface properties of readily formed nC60 changed fundamentally upon addition of NOM at environmental concentrations. For example, nC60 prepared through dissolution and removal of toluene solvent by sonication decreased in particle size, and the degree of particle size reduction was a function of solution chemistries. Bulk phase fullerene powder was directly dispersed into the aqueous phase as stable nC60 colloidal suspensions in presence of NOM at environmental concentrations in less than three days. In both cases, extremely small nC60 nanoparticles with diameter less than 10 nm were prevalently formed at specific solution conditions. The nC60 mass

  3. First soluble M@C60 derivatives provide enhanced access to metallofullerenes and permit in vivo evaluation of Gd@C60[C(COOH)2]10 as a MRI contrast agent.

    PubMed

    Bolskar, Robert D; Benedetto, Angelo F; Husebo, Lars O; Price, Roger E; Jackson, Edward F; Wallace, Sidney; Wilson, Lon J; Alford, J Michael

    2003-05-01

    M@C(60) and related endohedral metallofullerenes comprise a significant portion of the metallofullerene yield in the traditional arc synthesis, but their chemistry and potential applications have been largely overlooked because of their sparse solubility. In this work, procedures are described to solublize Gd@C(60) species for the first time by forming the derivative, Gd@C(60)[C(COOCH(2)CH(3))(2)](10), and its hydrolyzed water-soluble form, Gd@C(60)[C(COOH)(2)](10). Imparting water solubility to Gd@C(60) permits its evaluation as a magnetic resonance imaging (MRI) contrast agent. Relaxometry measurements for Gd@C(60)[C(COOH)(2)](10) reveal it to possess a relaxivity (4.6 mM(-1) s(-1) at 20 MHz and 40 degrees C) comparable to that of commercially available Gd(III) chelate-based MRI agents. An in vivo MRI biodistribution study in a rodent model reveals Gd@C(60)[C(COOH)(2)](10) to possess the first non-reticuloendothelial system (RES) localizing behavior for a water-soluble endohedral metallofullerene species, consistent with its lack of intermolecular aggregation in solution as determined by light-scattering measurements. This first derivatization and use of a M@C(60) species suggests new potential for metallofullerene technologies by reducing reliance on the chromatographic purification procedures normally employed for the far less abundant M@C(82) and related endohedrals. The recognition that water-soluble fullerene derivatives can be designed to avoid high levels of RES uptake is an important step toward fullerene-based pharmaceutical development.

  4. [Effect of fullerene C60 on free-radical induced lipid peroxidation processes in bronchial asthma].

    PubMed

    Bobrova, N A; Mikitiuk, M V; Kutsenko, L A; Kaĭdashev, I P

    2012-01-01

    Lipids peroxidative oxidation as well as antioxidative enzymes superoxidedismutase and catalase activity state at the mice sensibilization with ovalbumine, its correction with fulleren FC60 as well as by its forms (FC60-OVA, mFC60 mFC60-OVA) modified and conjugated with ovalbumines have been studied. It has been demonstrated that the mice sensibilization with ovalbumin leads to the tissues peroxidative lipid oxidation processes enforcement as well as lowering antioxidative enzymes activity in lungs and spleen. Used different rulleren forms expressed antioxidative effect and modifying effect to antioxidative protection enzymes at a given pathology. The influence of fulleren FC 60 and its modified form (1,2-methanofulleren-C60)61-carbolacid was the mostly effective. The data recieved testify to the prospects of the fullerens further investigation as the potential medicines. PMID:23072122

  5. Toxicity of fullerene (C60) to sediment-dwelling invertebrate Chironomus riparius larvae.

    PubMed

    Waissi-Leinonen, Greta C; Petersen, Elijah J; Pakarinen, Kukka; Akkanen, Jarkko; Leppänen, Matti T; Kukkonen, Jussi V K

    2012-09-01

    An environmentally realistic method to test fullerene (C(60) ) toxicity to the benthic organism Chironomus riparius was created by allowing suspended fullerenes to settle down, making a layer on top of the sediment. To test the hypothesis that higher food concentrations will reduce toxic responses, two food concentrations were tested (0.5 and 0.8% Urtica sp.) in sediment containing fullerene masses of 0.36 to 0.55 mg/cm(2) using a 10-d chronic test. In the 0.5% food level treatments, there were significant differences in all growth-related endpoints compared with controls. Fewer effects were observed for the higher food treatment. Fullerene agglomerates were observed by electron microscopy in the gut, but no absorption into the gut epithelial cells was detected. In the organisms exposed to fullerenes, microvilli were damaged and were significantly shorter. The potential toxicity of fullerene to C. riparius appears to be caused by morphological changes, inhibiting larval growth.

  6. Tight-binding molecular dynamics simulations of radiation-induced fragmentation of C60

    NASA Astrophysics Data System (ADS)

    Horváth, Lóránd; Beu, Titus A.

    2008-02-01

    The fragmentation of the C60 fullerene was investigated using tight-binding molecular dynamics simulations based on the parametrization of Papaconstantopoulos [MRS Symposia Proceedings No. 491 (Materials Research Society, Pittsburgh, 1998), p. 221]. Averaged fragment size distributions over random sets of initial configurations were obtained from simulations of radiation-induced fragmentation in the 50-500eV excitation energy range. The excitation caused by the radiation was simulated simply by ascribing suddenly random velocities to each atom of the fullerene cage. For low excitation energies, the size distributions are peaked for dimers (reflecting a preferential C2 emission) and a bimodal size dependence characterizes the distributions of the complementary small and large fragments. For high excitation energies, predominantly multifragmentation occurs, but a genuine power-law dependence of small fragments is not yet observable. A phase transition is found for rather low excitation energies (100-120eV) .

  7. "Compressed graphite" formed during C60 to diamond transformation as revealed by scattering computed tomography.

    PubMed

    Álvarez-Murga, M; Bleuet, P; Garbarino, G; Salamat, A; Mezouar, M; Hodeau, J L

    2012-07-13

    The collapsing of C60 into polycrystalline diamond has been studied after nonhydrostatic pressurization at ambient temperature using x-ray scattering computed tomography. Using this selective structural probe we provide evidence of concentric coexistence of "compressed graphite" (d(00l)∼3.09-3.11  Å), sp2-graphitelike phase (d(00l)∼3.35-3.42  Å), and sp3-like amorphous carbon surrounding polycrystalline diamond (a∼3.56-3.59  Å). The so-called "compressed graphite" exhibits a collapsed c axis and is textured with disordered layers. This latter phase is better described as a short interlayered carbon phase with buckled sp2-sp3 layers with possible interlayer bonding. Additionally, our 3D maps of phase distribution and of the residual stress retained in the polycrystalline diamond phase support the importance of stressed synthesis conditions for diamond formation.

  8. Nanocrystalline diamond thin films deposited from C60 monoenergetic fullerene ion beam.

    PubMed

    Pukha, V E; Stetsenko, A N; Dub, S N; Lee, J K

    2007-01-01

    Carbon films 250 division by 500 nm in thickness deposited on Si wafers from mass-selected flow of accelerated C60 ions with energies of 5.0 +/- 0.1 keV at temperatures of 300 K and 673 K are characterized by TEM and nanoindentation. On the TEM images of the films deposited at 673 K, nanocrystalline graphite with the typical grain size of -6 nm is observed. The films deposited at 300 K are transparent in visible light. TEM study of these films has revealed structural elements with lattice spacing close to that of diamond and the grain size of about 4 nm. Nanohardness and elastic modulus of the films prepared at a substrate temperature of 300 K were 23.1 +/- 0.2 GPa and 200 +/- 1 GPa, respectively. Possible mechanisms of the carbon films structure formation are suggested in the framework of a hydrodynamic shock wave model.

  9. C2 Fragmentation Energy of C60 Revisited: Theory Disagrees with Most Experiments

    NASA Technical Reports Server (NTRS)

    Boese, A. Daniel; Scuseria, Gustavo E.

    1998-01-01

    Following our earlier work on the subject, we have carried out density functional theory (DFT) and second-order Moller-Plesset perturbation theory (MP2) calculations of the dissociation energy of the reaction C60 yields C58 + C2 using polarized basis sets and geometries optimized with DFT methods. The present theoretical results support an electronic fragmentation energy D(sub e) around 10-11 eV in disagreement with most experimental results that place the dissociation energy D(sub o) (including zero point energy) around 7-8 eV. The plausible errors remaining in the theoretical calculations are unlikely to account for this big difference (2-4 eV).

  10. Phase transformations in amorphous fullerite C60 under high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Borisova, P. A.; Blanter, M. S.; Brazhkin, V. V.; Somenkov, V. A.; Filonenko, V. P.

    2015-08-01

    First phase transformations of amorphous fullerite C60 at high temperatures (up to 1800 K) and high pressures (up to 8 GPa) have been investigated and compared with the previous studies on the crystalline fullerite. The study was conducted using neutron diffraction and Raman spectroscopy. The amorphous fullerite was obtained by ball-milling. We have shown that under thermobaric treatment no crystallization of amorphous fullerite into С60 molecular modification is observed, and it transforms into amorphous-like or crystalline graphite. A kinetic diagram of phase transformation of amorphous fullerite in temperature-pressure coordinates was constructed for the first time. Unlike in crystalline fullerite, no crystalline polymerized phases were formed under thermobaric treatment on amorphous fullerite. We found that amorphous fullerite turned out to be less resistant to thermobaric treatment, and amorphous-like or crystalline graphite were formed at lower temperatures than in crystalline fullerite.

  11. Transmission secondary ion mass spectrometry using 5 MeV C60+ ions

    NASA Astrophysics Data System (ADS)

    Nakajima, K.; Nagano, K.; Suzuki, M.; Narumi, K.; Saitoh, Y.; Hirata, K.; Kimura, K.

    2014-03-01

    In the secondary ion mass spectrometry (SIMS), use of cluster ions has an advantage of producing a high sensitivity of intact large molecular ions over monatomic ions. This paper presents further yield enhancement of the intact biomolecular ions by measuring the secondary ions emitted in the forward direction. Phenylalanine amino acid films deposited on self-supporting thin Si3N4 films were bombarded with 5 MeV C60 ions. Secondary ions emitted in the forward and backward directions were measured. The yield of intact phenylalanine molecular ions emitted in the forward direction is significantly enhanced compared to the backward direction while fragment ions are suppressed. This suggests a large potential of using transmission cluster ion SIMS for the analysis of biological materials.

  12. Exploring two-dimensional soap-foam films using fullerene (C60) nanosensors

    NASA Astrophysics Data System (ADS)

    Maguire, John F.; Amer, Maher S.; Busbee, John

    2003-04-01

    A large number of studies have been devoted to the investigation of foam structure formation, characteristics, and stability. In this paper, we use fullerene (C60) spheres as Raman active nanosensors to probe the local chemical environment in a two-dimensional soap foam. It has been found that the position of the Raman active pentagon pinch mode around 1469 cm-1 shifts to lower wave numbers with the increase in the angle between foam-cell boundaries. The observed shift is due to changes in the local chemical interaction between the nanosensor and its environment. The study demonstrates that fullerenes may be used as sensitive nanoscale sensors to probe the local chemical potential in soft and interfacial materials, and more importantly in thermodynamically small systems.

  13. Stereodivergent Synthesis of Chiral Fullerenes by [3 + 2] Cycloadditions to C60

    PubMed Central

    2013-01-01

    A wide range of new dipoles and catalysts have been used in 1,3-dipolar cycloadditions of N-metalated azomethine ylides onto C60 yielding a full stereodivergent synthesis of pyrrolidino[60]fullerenes with complete diastereoselectivities and very high enantioselectivities. The use of less-explored chiral α-iminoamides as starting 1,3-dipoles leads to an interesting double asymmetric induction resulting in a matching/mismatching effect depending upon the absolute configuration of the stereocenter in the starting α-iminoamide. An enantioselective process was also found in the retrocycloaddition reaction as revealed by mass spectrometry analysis on quasi-enantiomeric pyrrolidino[60]fullerenes. Theoretical DFT calculations are in very good agreement with the experimental data. On the basis of this agreement, a plausible reaction mechanism is proposed. PMID:24359021

  14. Tandem white organic light-emitting diodes adopting a C60:rubrene charge generation layer

    NASA Astrophysics Data System (ADS)

    Bi, Wen-Tao; Wu, Xiao-Ming; Hua, Yu-Lin; Sun, Jin-E.; Xiao, Zhi-Hui; Wang, Li; Yin, Shou-Gen

    2014-01-01

    Organic bulk heterojunction fullerence (C60) doped 5, 6, 11, 12-tetraphenylnaphthacene (rubrene) as the high quality charge generation layer (CGL) with high transparency and superior charge generating capability for tandem organic light emitting diodes (OLEDs) is developed. This CGL shows excellent optical transparency about 90%, which can reduce the optical interference effect formed in tandem OLEDs. There is a stable white light emission including 468 nm and 500 nm peaks from the blue emitting layer and 620 nm peak from the red emitting layer in tandem white OLEDs. A high efficiency of about 17.4 cd/A and CIE coordinates of (0.40, 0.35) at 100 cd/m2 and (0.36, 0.34) at 1000 cd/m2 have been demonstrated by employing the developed CGL, respectively.

  15. Analysis of the interface and its position in C60(n+) secondary ion mass spectrometry depth profiling.

    PubMed

    Green, F M; Shard, A G; Gilmore, I S; Seah, M P

    2009-01-01

    C60(n+) ions have been shown to be extremely successful for SIMS depth profiling of a wide range of organic materials, causing significantly less degradation of the molecular information than more traditional primary ions. This work focuses on examining the definition of the interface in a C60(n+) SIMS depth profile for an organic overlayer on a wafer substrate. First it investigates the optimum method to define the organic/inorganic interface position. Variations of up to 8 nm in the interface position can arise from different definitions of the interface position in the samples investigated here. Second, it looks into the reasons behind large interfacial widths, i.e., poor depth resolution, seen in C60(n+) depth profiling. This work confirms that, for Irganox 1010 deposited on a wafer, the depth resolution at the Irganox 1010/substrate interface is directly correlated to the roughening of material. C60n+ PMID:19117445

  16. SERS of C60/C70 on gold-coated filter paper or filter film influenced by the gold thickness.

    PubMed

    Luo, Zhixun; Fang, Yan

    2005-03-15

    SERS of C(60)/C(70) adsorbed on gold nanoparticles coated on filter paper or filter film was studied. As a new SERS substrate, dried gold-coated filter paper or filter film has a high SERS activity, whose enhancement factor can be up to about 10(5), because it avoided the influence of solvents in C(60)/C(70) solution and water in gold hydrosols. The influence of the gold thickness coated on filter paper or filter film to SERS of C(60)/C(70) adsorbed on gold nanoparticles was mainly discussed. It is indicated that the SERS effect of C(60)/C(70) was very sensitive to the distribution and aggregated characteristics of gold nanoparticles, and the SERS intensity of each mode increased at its own proportion, but it integrally tended to saturation when the thickness of colloidal gold coatings increased.

  17. Fullerene C60 functionalized γ-Fe2O3 magnetic nanoparticle: Synthesis, characterization, and biomedical applications.

    PubMed

    Kılınç, Ersin

    2016-01-01

    Hybrid magnetic nanoparticles composed from C60 fullerene and γ-Fe2O3 were synthesized by hydrothermal method. XRD, FT-IR, VSM, SEM, and HR-TEM were employed for characterizations. The magnetic saturation value of C60-γ-Fe2O3 magnetic nanoparticles was 66.5 emu g(-1). Concentration of Fe in nanoparticles as determined by ICP-OES was 40.7% Fe. Particle size of C60-γ-Fe2O3 magnetic nanoparticles was smaller than 10 nm. Maximum adsorption capacity of C60-γ-Fe2O3 for flurbiprofen, a non-steroidal anti-inflammatory drug, was calculated from Langmuir isotherm as 142.9 mg g(-1).

  18. Interaction of C60 fullerene complexed to doxorubicin with model bilipid membranes and its uptake by HeLa cells.

    PubMed

    Prylutskyy, Yu; Bychko, A; Sokolova, V; Prylutska, S; Evstigneev, M; Rybalchenko, V; Epple, M; Scharff, P

    2016-02-01

    With an aim to elucidate the effects of C60 fullerene complexed with antibiotic doxorubicin (Dox) on model bilipid membranes (BLM), the investigation of the electrical properties of BLM under the action of Dox and C60 fullerene, and of their complex, C60+Dox,was performed. The complex as well as its components exert a clearly detectable influence on BLM, which is concentration-dependent and also depends on phospholipid composition. The mechanism of this effect originates either from intermolecular interaction of the drug with fatty-acid residues of phospholipids, or from membranotropic effects of the drug-induced lipid peroxidation, or from the sum of these two effects. By fluorescence microscopy the entering of C60 + Dox complex into HeLa cells was directly shown.

  19. Near-Infrared Photoelectrochemical Conversion via Photoinduced Charge Separation in Supramolecular Complexes of Anionic Phthalocyanines with Li(+)@C60.

    PubMed

    Kawashima, Yuki; Ohkubo, Kei; Blas-Ferrando, Vicente Manuel; Sakai, Hayato; Font-Sanchis, Enrique; Ortíz, Javier; Fernández-Lázaro, Fernando; Hasobe, Taku; Sastre-Santos, Ángela; Fukuzumi, Shunichi

    2015-06-18

    Two phthalocyanines possessing carboxylate groups ((TBA)4H2Pc·1 and (TBA)4H2Pc·2) form 1:2 supramolecular complexes with lithium cation-encapsulated C60 (Li(+)@C60) [H2Pc·1(4-)/(Li(+)@C60)2 and H2Pc·2(4-)/(Li(+)@C60)2] in a polar mixed solvent. From the UV-vis spectral changes, the binding constants (K) were estimated as ca. 10(12) M(-2). Upon the photoexcitation of constructed supramolecular complexes, photoinduced electron transfer occurred to form the charge-separated (CS) state. The lifetime of the CS state was determined to be 1.2 ms for H2Pc·2(4-)/(Li(+)@C60)2, which is the longest CS lifetime among the porphyrinoid/fullerene supramolecular complexes. H2Pc·1(4-)/(Li(+)@C60)2 also afforded the long-lived CS state of 1.0 ms. The spin state of the long-lived CS states was determined to be a triplet, as indicated by the EPR signal at g = 4. The reorganization energy (λ) and the electronic coupling term were determined to be λ = 1.70 eV, V = 0.15 cm(-1) from the temperature dependence of the rate constant for the charge recombination of the CS state of H2Pc·1(4-)/(Li(+)@C60)2. The energy of the CS state (0.49 eV) is much smaller than the reorganization energy, indicating that the back-electron-transfer process is located in the Marcus normal region. The small electronic coupling term results from the spin-forbidden back electron transfer due to the triplet CS state. Supramolecular complexes of anionic zinc phthalocyanines with Li(+)@C60 were also prepared and investigated. The ZnPc·4(4-)/Li(+)@C60 supramolecular nanoclusters were assembled on the optically transparent electrode (OTE) of nanostructured SnO2 (OTE/SnO2) to construct the dye-sensitized solar cell. The IPCE (incident photon-to-photocurrent efficiency) values of OTE/SnO2/(ZnPc·4(4-)/Li(+)@C60)n were much higher than the sum of the two IPCE values of the individual systems OTE/SnO2/(Li(+)@C60)n and OTE/SnO2/(ZnPc·4(4-))n, covering the near-infrared region.

  20. Near-Infrared Photoelectrochemical Conversion via Photoinduced Charge Separation in Supramolecular Complexes of Anionic Phthalocyanines with Li(+)@C60.

    PubMed

    Kawashima, Yuki; Ohkubo, Kei; Blas-Ferrando, Vicente Manuel; Sakai, Hayato; Font-Sanchis, Enrique; Ortíz, Javier; Fernández-Lázaro, Fernando; Hasobe, Taku; Sastre-Santos, Ángela; Fukuzumi, Shunichi

    2015-06-18

    Two phthalocyanines possessing carboxylate groups ((TBA)4H2Pc·1 and (TBA)4H2Pc·2) form 1:2 supramolecular complexes with lithium cation-encapsulated C60 (Li(+)@C60) [H2Pc·1(4-)/(Li(+)@C60)2 and H2Pc·2(4-)/(Li(+)@C60)2] in a polar mixed solvent. From the UV-vis spectral changes, the binding constants (K) were estimated as ca. 10(12) M(-2). Upon the photoexcitation of constructed supramolecular complexes, photoinduced electron transfer occurred to form the charge-separated (CS) state. The lifetime of the CS state was determined to be 1.2 ms for H2Pc·2(4-)/(Li(+)@C60)2, which is the longest CS lifetime among the porphyrinoid/fullerene supramolecular complexes. H2Pc·1(4-)/(Li(+)@C60)2 also afforded the long-lived CS state of 1.0 ms. The spin state of the long-lived CS states was determined to be a triplet, as indicated by the EPR signal at g = 4. The reorganization energy (λ) and the electronic coupling term were determined to be λ = 1.70 eV, V = 0.15 cm(-1) from the temperature dependence of the rate constant for the charge recombination of the CS state of H2Pc·1(4-)/(Li(+)@C60)2. The energy of the CS state (0.49 eV) is much smaller than the reorganization energy, indicating that the back-electron-transfer process is located in the Marcus normal region. The small electronic coupling term results from the spin-forbidden back electron transfer due to the triplet CS state. Supramolecular complexes of anionic zinc phthalocyanines with Li(+)@C60 were also prepared and investigated. The ZnPc·4(4-)/Li(+)@C60 supramolecular nanoclusters were assembled on the optically transparent electrode (OTE) of nanostructured SnO2 (OTE/SnO2) to construct the dye-sensitized solar cell. The IPCE (incident photon-to-photocurrent efficiency) values of OTE/SnO2/(ZnPc·4(4-)/Li(+)@C60)n were much higher than the sum of the two IPCE values of the individual systems OTE/SnO2/(Li(+)@C60)n and OTE/SnO2/(ZnPc·4(4-))n, covering the near-infrared region. PMID:25615010

  1. Application of C60 Fullerene-Doxorubicin Complex for Tumor Cell Treatment In Vitro and In Vivo.

    PubMed

    Panchuk, R R; Prylutska, S V; Chumakl, V V; Skorokhyd, N R; Lehka, L V; Evstigneev, M P; Prylutskyy, Yu I; Berger, W; Heffeter, P; Scharff, P; Ritter, U; Stoika, R S

    2015-07-01

    Development of nanocarriers for effective drug delivery to molecular targets in tumor cells is a real problem in modern pharmaceutical chemistry. In the present work we used pristine C60 fullerene as a platform for delivery of anticancer drug doxorubicin (Dox) to its biological targets. The formation of a complex of C60 fullerene with Dox (C60 + Dox) is described and physico-chemical characteristics of such complex are presented. It was found that Dox conjugation with C60 fullerene leads to 1.5-2-fold increase in Dox toxicity towards various human tumor cell lines, compared with such effect when the drug is used alone. Cytotoxic activity of C60 + Dox complex is accompanied by an increased level of cell produced hydrogen peroxide at early time point (3 h) after its addition to cultured cells. At the same time, cellular production of superoxide radicals does not change in comparison with the effect of Dox alone. Cytomorphological studies have demonstrated that C60 + Dox complexes kill tumor cells by apoptosis induction. The results of in vivo experiments using Lewis lung carcinoma in mice confirmed the enhancement of the Dox toxicity towards tumor cells after drug complexation with C60 fullerene. The effect of such complex towards tumor-bearing mice was even more pronounced than that in the in vitro experiment with targeting human tumor cells. The tumor volume decreased by 2.5 times compared with the control, and an average life span of treated animals increased by 63% compared with control. The obtained results suggest a great perspective of application of C60 + Dox complexes for chemotherapy of malignant tumors.

  2. Visible light sensitized inactivation of MS-2 bacteriophage by a cationic amine-functionalized C60 derivative.

    PubMed

    Cho, Min; Lee, Jaesang; Mackeyev, Yuri; Wilson, Lon J; Alvarez, Pedro J J; Hughes, Joseph B; Kim, Jae-Hong

    2010-09-01

    Recently, we reported the successful synthesis of various hexakis C60 derivatives (i.e., C60 with six functional groups containing NH3+-, CO2H-, or OH-terminals) with enhanced stability in water for aqueous phase application (Lee et al., Environ. Sci. Technol. 2009, 43, pp 6604-6610). Among these newly synthesized C60 derivatives, the cationic hexakis C60 derivative with amine functionality, C60(CR2)6 (R=CO2(CH2)2NH3+CF3CO2-), was found to exhibit remarkable efficiency to inactivate Escherichia coli and MS-2 bacteriophage under UVA irradiation. Herein, we report that this amine-functionalized C60 derivative is also photoactive in response to visible light from both commercial fluorescence lamps and sunlight. Efficient production of 1O2, facile reaction of 1O2 with proteins in MS-2 phage capsid and electrostatic attraction between positively charged C60 derivative and negatively charged MS-2 phage collectively contributed to high efficiency of MS-2 phage inactivation in this photocatalytic disinfection system. The rate of 1O2 production was evaluated using a probe compound, furfuryl alcohol, and 1O2 CT (the product of 1O2 concentration and exposure time) required to achieve a target level of virus inactivation was quantitatively analyzed. The unique visible-light sensitized virucidal property makes this C60 derivative highly desirable for the development of sustainable disinfection strategies that do not require continuous chemical addition nor an external energy source other than ambient light.

  3. Application of C60 Fullerene-Doxorubicin Complex for Tumor Cell Treatment In Vitro and In Vivo.

    PubMed

    Panchuk, R R; Prylutska, S V; Chumakl, V V; Skorokhyd, N R; Lehka, L V; Evstigneev, M P; Prylutskyy, Yu I; Berger, W; Heffeter, P; Scharff, P; Ritter, U; Stoika, R S

    2015-07-01

    Development of nanocarriers for effective drug delivery to molecular targets in tumor cells is a real problem in modern pharmaceutical chemistry. In the present work we used pristine C60 fullerene as a platform for delivery of anticancer drug doxorubicin (Dox) to its biological targets. The formation of a complex of C60 fullerene with Dox (C60 + Dox) is described and physico-chemical characteristics of such complex are presented. It was found that Dox conjugation with C60 fullerene leads to 1.5-2-fold increase in Dox toxicity towards various human tumor cell lines, compared with such effect when the drug is used alone. Cytotoxic activity of C60 + Dox complex is accompanied by an increased level of cell produced hydrogen peroxide at early time point (3 h) after its addition to cultured cells. At the same time, cellular production of superoxide radicals does not change in comparison with the effect of Dox alone. Cytomorphological studies have demonstrated that C60 + Dox complexes kill tumor cells by apoptosis induction. The results of in vivo experiments using Lewis lung carcinoma in mice confirmed the enhancement of the Dox toxicity towards tumor cells after drug complexation with C60 fullerene. The effect of such complex towards tumor-bearing mice was even more pronounced than that in the in vitro experiment with targeting human tumor cells. The tumor volume decreased by 2.5 times compared with the control, and an average life span of treated animals increased by 63% compared with control. The obtained results suggest a great perspective of application of C60 + Dox complexes for chemotherapy of malignant tumors. PMID:26307837

  4. The enthalpy of formation of fullerene fluoride C60F18 and the C-F bond energy

    NASA Astrophysics Data System (ADS)

    Papina, T. S.; Luk'yanova, V. A.; Goryunkov, A. A.; Ioffe, I. N.; Gol'Dt, I. V.; Buyanovskaya, A. G.; Kabaeva, N. M.; Sidorov, L. N.

    2007-10-01

    The enthalpy of combustion of crystalline fullerene fluoride C60F18 was determined in an isoperibolic calorimeter with a rotating platinized bomb, and the enthalpy of formation of the compound was calculated. The enthalpy of sublimation of C60F18 measured earlier was used to calculate the enthalpy of formation of fullerene fluoride in the gas phase and the mean enthalpy of dissociation of C-F bonds in this compound.

  5. Visible light sensitized inactivation of MS-2 bacteriophage by a cationic amine-functionalized C60 derivative.

    PubMed

    Cho, Min; Lee, Jaesang; Mackeyev, Yuri; Wilson, Lon J; Alvarez, Pedro J J; Hughes, Joseph B; Kim, Jae-Hong

    2010-09-01

    Recently, we reported the successful synthesis of various hexakis C60 derivatives (i.e., C60 with six functional groups containing NH3+-, CO2H-, or OH-terminals) with enhanced stability in water for aqueous phase application (Lee et al., Environ. Sci. Technol. 2009, 43, pp 6604-6610). Among these newly synthesized C60 derivatives, the cationic hexakis C60 derivative with amine functionality, C60(CR2)6 (R=CO2(CH2)2NH3+CF3CO2-), was found to exhibit remarkable efficiency to inactivate Escherichia coli and MS-2 bacteriophage under UVA irradiation. Herein, we report that this amine-functionalized C60 derivative is also photoactive in response to visible light from both commercial fluorescence lamps and sunlight. Efficient production of 1O2, facile reaction of 1O2 with proteins in MS-2 phage capsid and electrostatic attraction between positively charged C60 derivative and negatively charged MS-2 phage collectively contributed to high efficiency of MS-2 phage inactivation in this photocatalytic disinfection system. The rate of 1O2 production was evaluated using a probe compound, furfuryl alcohol, and 1O2 CT (the product of 1O2 concentration and exposure time) required to achieve a target level of virus inactivation was quantitatively analyzed. The unique visible-light sensitized virucidal property makes this C60 derivative highly desirable for the development of sustainable disinfection strategies that do not require continuous chemical addition nor an external energy source other than ambient light. PMID:20687548

  6. Mechanochemical synthesis of a novel C(60) dimer connected by a silicon bridge and a single bond.

    PubMed

    Fujiwara, Koichi; Komatsu, Koichi

    2002-03-21

    [reaction: see text] A novel C(60) dimer connected by a silicon bridge and a single bond was synthesized by the mechanochemical solid-state reaction employing a high-speed vibration milling technique and fully characterized by the (1)H and (13)C NMR, APCI mass, and UV-vis spectroscopy. The presence of the electronic interaction between the two C(60) cages was demonstrated by the electrochemical method.

  7. Activation Effect of Fullerene C60 on the Carbon Dioxide Absorption Performance of Amine-Rich Polypropylenimine Dendrimers.

    PubMed

    Andreoli, Enrico; Barron, Andrew R

    2015-08-24

    Converting amine-rich compounds into highly effective carbon dioxide (CO2 ) sorbents requires a better understanding and control of their properties. The reaction of fullerene C60 with polyethyleneimine converts the polymer into a high-performance CO2 sorbent. In this study, experimental evidence is reported for the activation effect of C60 on the amine moieties of the polymer. To do so, polypropylenimine (PPI) dendrimers that allowed for a systematic comparison of molecular composition and CO2 absorption were used. The addition of C60 to PPI to form PPI-C60 results in a reduction of the energy barrier of CO2 absorption, but also in a parallel decrease in the frequency of successful collisions between CO2 and PPI-C60 due to a possible disruption of the hydrogen-bonding network of amino groups and bound water in PPI. This finding supports the existence of a non-affinity "repulsive" effect between hydrophobic C60 and hydrophilic amines that forces them to be actively exposed to CO2. PMID:26223905

  8. Characterization of Plasma Gun with TiH2/C60 Cartridge for Disruption Mitigation in Tokamaks

    NASA Astrophysics Data System (ADS)

    Bogatu, I. N.; Thompson, J. R.; Galkin, S. A.; Kim, J. S.; HyperV Technologies Corp. Team

    2011-10-01

    Impurity injection for disruption mitigation in tokamaks must be faster than growth time of plasma instabilities, requires sufficient mass to get critical electron density, high penetrability, and large assimilation fraction in the core plasma, with rapid impurity redistribution over the whole plasma. FAR-TECH, Inc. proposed the innovative idea to use hyper-velocity (>30 km/s), high-density (>1023 m-3) C60/C plasma jets with high ram pressure to deliver the impurity mass in <1 ms. For this purpose C60 powder explosively sublimated into molecular gas, from a solid state, pulsed power driven TiH2/C60 injector cartridge is ionized and accelerated in a plasma accelerator. We report the complete characterization of the TiH2/C60 cartridge with 5 kJ capacitive driver which demonstrated the capability of producing >30 mg of C60 gas in <0.5 ms. In addition we present the construction and testing status of a 100 kJ coaxial plasma gun (~35 cm length) prototype with TiH2/C60 cartridge for a small scale, proof-of-principle experiment on a tokamak. Work supported by the US DOE DE-FG02-08ER85196 grant.

  9. Influence of fullerene (C60) on soil bacterial communities: aqueous aggregate size and solvent co-introduction effects

    NASA Astrophysics Data System (ADS)

    Tong, Zhong-Hua; Bischoff, Marianne; Nies, Loring F.; Carroll, Natalie J.; Applegate, Bruce; Turco, Ronald F.

    2016-06-01

    Fullerene C60 nanoparticles are being used in broad range of applications. It is important to assess their potential impacts in the environment. We evaluated the effects of C60 introduced as aqueous suspensions of nC60 aggregates of different particle size or via organic solvents on soils with different organic matter contents in this study. Impacts of the application were evaluated by measuring total microbial biomass, metabolic activity and bacterial community structure. Results show that nC60 aggregates, introduced as an aqueous suspension, had size-dependent effects on soil bacterial community composition in the low organic matter system, but induced minimal change in the microbial biomass and metabolic activity in soils with both high and low organic matter contents. Fullerene C60, co-introduced via an organic solvent, did not influence the response of soil microbes to the organic solvents. Our results suggest that nC60 aggregates of smaller size may have negative impact on soil biota and soil organic matter may play a key role in modulating the environmental effect of nanomaterials.

  10. Direct observation of photocarrier electron dynamics in C60 films on graphite by time-resolved two-photon photoemission

    PubMed Central

    Shibuta, Masahiro; Yamamoto, Kazuo; Ohta, Tsutomu; Nakaya, Masato; Eguchi, Toyoaki; Nakajima, Atsushi

    2016-01-01

    Time-resolved two-photon photoemission (TR-2PPE) spectroscopy is employed to probe the electronic states of a C60 fullerene film formed on highly oriented pyrolytic graphite (HOPG), acting as a model two-dimensional (2D) material for multi-layered graphene. Owing to the in-plane sp2-hybridized nature of the HOPG, the TR-2PPE spectra reveal the energetics and dynamics of photocarriers in the C60 film: after hot excitons are nascently formed in C60 via intramolecular excitation by a pump photon, they dissociate into photocarriers of free electrons and the corresponding holes, and the electrons are subsequently detected by a probe photon as photoelectrons. The decay rate of photocarriers from the C60 film into the HOPG is evaluated to be 1.31 × 1012 s−1, suggesting a weak van der Waals interaction at the interface, where the photocarriers tentatively occupy the lowest unoccupied molecular orbital (LUMO) of C60. The photocarrier electron dynamics following the hot exciton dissociation in the organic thin films has not been realized for any metallic substrates exhibiting strong interactions with the overlayer. Furthermore, the thickness dependence of the electron lifetime in the LUMO reveals that the electron hopping rate in C60 layers is 3.3 ± 1.2 × 1013 s−1. PMID:27775005

  11. Impact of MoO3 interlayer on the energy level alignment of pentacene-C60 heterostructure.

    PubMed

    Zou, Ye; Mao, Hongying; Meng, Qing; Zhu, Daoben

    2016-02-28

    Using in situ ultraviolet photoelectron spectroscopy, the electronic structure evolutions at the interface between pentacene and fullerene (C60), a classical organic donor-acceptor heterostructure in organic electronic devices, on indium-tin oxide (ITO) and MoO3 modified ITO substrates have been investigated. The insertion of a thin layer MoO3 has a significant impact on the interfacial energy level alignment of pentacene-C60 heterostructure. For the deposition of C60 on pentacene, the energy difference between the highest occupied molecular orbital of donor and the lowest unoccupied molecular orbital of acceptor (HOMO(D)-LUMO(A)) offset of C60/pentacene heterostructure increased from 0.86 eV to 1.54 eV after the insertion of a thin layer MoO3 on ITO. In the inverted heterostructrure where pentacene was deposited on C60, the HOMO(D)-LUMO(A) offset of pentacene/C60 heterostructure increased from 1.32 to 2.20 eV after MoO3 modification on ITO. The significant difference of HOMO(D)-LUMO(A) offset shows the feasibility to optimize organic electronic device performance through interfacial engineering approaches, such as the insertion of a thin layer high work function MoO3 films. PMID:26931717

  12. Activation Effect of Fullerene C60 on the Carbon Dioxide Absorption Performance of Amine-Rich Polypropylenimine Dendrimers.

    PubMed

    Andreoli, Enrico; Barron, Andrew R

    2015-08-24

    Converting amine-rich compounds into highly effective carbon dioxide (CO2 ) sorbents requires a better understanding and control of their properties. The reaction of fullerene C60 with polyethyleneimine converts the polymer into a high-performance CO2 sorbent. In this study, experimental evidence is reported for the activation effect of C60 on the amine moieties of the polymer. To do so, polypropylenimine (PPI) dendrimers that allowed for a systematic comparison of molecular composition and CO2 absorption were used. The addition of C60 to PPI to form PPI-C60 results in a reduction of the energy barrier of CO2 absorption, but also in a parallel decrease in the frequency of successful collisions between CO2 and PPI-C60 due to a possible disruption of the hydrogen-bonding network of amino groups and bound water in PPI. This finding supports the existence of a non-affinity "repulsive" effect between hydrophobic C60 and hydrophilic amines that forces them to be actively exposed to CO2.

  13. Influence of fullerene (C60) on soil bacterial communities: aqueous aggregate size and solvent co-introduction effects.

    PubMed

    Tong, Zhong-Hua; Bischoff, Marianne; Nies, Loring F; Carroll, Natalie J; Applegate, Bruce; Turco, Ronald F

    2016-01-01

    Fullerene C60 nanoparticles are being used in broad range of applications. It is important to assess their potential impacts in the environment. We evaluated the effects of C60 introduced as aqueous suspensions of nC60 aggregates of different particle size or via organic solvents on soils with different organic matter contents in this study. Impacts of the application were evaluated by measuring total microbial biomass, metabolic activity and bacterial community structure. Results show that nC60 aggregates, introduced as an aqueous suspension, had size-dependent effects on soil bacterial community composition in the low organic matter system, but induced minimal change in the microbial biomass and metabolic activity in soils with both high and low organic matter contents. Fullerene C60, co-introduced via an organic solvent, did not influence the response of soil microbes to the organic solvents. Our results suggest that nC60 aggregates of smaller size may have negative impact on soil biota and soil organic matter may play a key role in modulating the environmental effect of nanomaterials. PMID:27306076

  14. Influence of fullerene (C60) on soil bacterial communities: aqueous aggregate size and solvent co-introduction effects

    PubMed Central

    Tong, Zhong-Hua; Bischoff, Marianne; Nies, Loring F.; Carroll, Natalie J.; Applegate, Bruce; Turco, Ronald F.

    2016-01-01

    Fullerene C60 nanoparticles are being used in broad range of applications. It is important to assess their potential impacts in the environment. We evaluated the effects of C60 introduced as aqueous suspensions of nC60 aggregates of different particle size or via organic solvents on soils with different organic matter contents in this study. Impacts of the application were evaluated by measuring total microbial biomass, metabolic activity and bacterial community structure. Results show that nC60 aggregates, introduced as an aqueous suspension, had size-dependent effects on soil bacterial community composition in the low organic matter system, but induced minimal change in the microbial biomass and metabolic activity in soils with both high and low organic matter contents. Fullerene C60, co-introduced via an organic solvent, did not influence the response of soil microbes to the organic solvents. Our results suggest that nC60 aggregates of smaller size may have negative impact on soil biota and soil organic matter may play a key role in modulating the environmental effect of nanomaterials. PMID:27306076

  15. Geometrical Structure and Interface Dependence of Bias Stress Induced Threshold Voltage Shift in C60-Based OFETs

    PubMed Central

    2014-01-01

    The influence of the nature of interface between organic semiconductor and gate dielectric on bias stress electrical stability of n-type C60-based organic field effect transistors (OFETs) was studied. The bias stress induced threshold voltage (Vth) shift was found to depend critically on the OFET device structure: the direction of Vth shift in top-gate OFETs was opposite to that in bottom-gate OFETs, while the use of the dual-gate OFET structure resulted in just very small variations in Vth. The opposite direction of Vth shift is attributed to the different nature of interfaces between C60 semiconductor and Parylene dielectric in these devices. The Vth shift to more positive voltages upon bias stress in bottom-gate C60-OFET was similar to that observed for other n-type semiconductors and rationalized by electron trapping in the dielectric or at the gate dielectric/C60 interface. The opposite direction of Vth shift in top-gate C60-OFETs is attributed to free radical species created in the course of Parylene deposition on the surface of C60 during device fabrication, which produce plenty of hole traps. It was also realized that the dual-gate OFETs gives stable characteristics, which are immune to bias stress effects. PMID:25142130

  16. Immunotoxicity of nanoparticles: a computational study suggests that CNTs and C60 fullerenes might be recognized as pathogens by Toll-like receptors

    NASA Astrophysics Data System (ADS)

    Turabekova, M.; Rasulev, B.; Theodore, M.; Jackman, J.; Leszczynska, D.; Leszczynski, J.

    2014-03-01

    Over the last decade, a great deal of attention has been devoted to study the inflammatory response upon exposure to multi/single-walled carbon nanotubes (CNTs) and different fullerene derivatives. In particular, carbon nanoparticles are reported to provoke substantial inflammation in alveolar and bronchial epithelial cells, epidermal keratinocytes, cultured monocyte-macrophage cells, etc. We suggest a hypothetical model providing the potential mechanistic explanation for immune and inflammatory responses observed upon exposure to carbon nanoparticles. Specifically, we performed a theoretical study to analyze CNT and C60 fullerene interactions with the available X-ray structures of Toll-like receptors (TLRs) homo- and hetero-dimer extracellular domains. This assumption was based on the fact that similar to the known TLR ligands both CNTs and fullerenes induce, in cells, the secretion of certain inflammatory protein mediators, such as interleukins and chemokines. These proteins are observed within inflammation downstream processes resulted from the ligand molecule dependent inhibition or activation of TLR-induced signal transduction. Our computational studies have shown that the internal hydrophobic pockets of some TLRs might be capable of binding small-sized carbon nanostructures (5,5 armchair SWCNTs containing 11 carbon atom layers and C60 fullerene). High binding scores and minor structural alterations induced in TLR ectodomains upon binding C60 and CNTs further supported our hypothesis. Additionally, the proposed hypothesis is strengthened by the indirect experimental findings indicating that CNTs and fullerenes induce an excessive expression of specific cytokines and chemokines (i.e. IL-8 and MCP1).Over the last decade, a great deal of attention has been devoted to study the inflammatory response upon exposure to multi/single-walled carbon nanotubes (CNTs) and different fullerene derivatives. In particular, carbon nanoparticles are reported to provoke

  17. Photo excitation and laser detachment of C60- anions in a storage ring

    NASA Astrophysics Data System (ADS)

    Støchkel, K.; Andersen, J. U.

    2013-10-01

    We have studied the photo physics of C60- anions in the electrostatic storage ring ELISA with ions produced in a plasma source and cooled and bunched in a He filled ion trap. A previous study using delayed electron detachment as a signal of resonance-enhanced multiphoton electron detachment (REMPED) has been repeated both at room temperature and with the trap cooled to liquid nitrogen temperature. However, wavelength dependence of the overlap of the strongly focused laser beam with the ion beam introduces distortions of the absorption spectrum. We have therefore applied a new method, combining the IR light with a slightly delayed, powerful UV pulse (266 nm). After absorption of three UV photons, the ions decay by delayed (thermal) electron emission, and time spectra are recorded for varying wavelength. The fraction of ions heated by absorption of a single IR photon is then extracted from a principal component analysis of these spectra. In good agreement with the earlier REMPED experiment, an origin band for transitions between the two lowest electronic levels of the anion, with t1u and t1g symmetry, is observed at 9380 cm-1, with strong sidebands from excitation of the two Ag and eight Hg vibrations. As before, a hot band is observed at about 9150 cm-1 and assigned to a transition from an excited vibronic Jahn-Teller state. However, an earlier observed band at higher energy, interpreted as a transition from this excited state to an excited vibronic state in the t1g electronic level, is much weaker in the new measurements and could be an Hg vibrational sideband. Also earlier studies of direct laser detachment from C60- in the storage ring ASTRID have been revisited, with ions cooled by liquid nitrogen in the ion trap. We confirm the previous measurement with a determination of the threshold for s-wave detachment at 2.664 ± 0.005 eV, slightly lower than a recent value of the electron binding, 2.683 ± 0.008 eV, obtained from the energy spectrum of photo electrons

  18. Clinical evaluation of fullerene-C60 dissolved in squalane for anti-wrinkle cosmetics.

    PubMed

    Kato, Shinya; Taira, Hikaru; Aoshima, Hisae; Saitoh, Yasukazu; Miwa, Nobuhiko

    2010-10-01

    Highly purified and organic solvent-free fullerene-C60 was dissolved, at nearly saturated concentration of 278 ppm, in squalane prepared from olive oil, which is designated as LipoFullerene (LF-SQ) and was examined for usage as a cosmetic ingredient with antioxidant ability. The aim of this study was to assess the anti-wrinkle formation efficacy of LF-SQ in subjects. A total of 23 Japanese women (group I: age 38.9 +/- 3.8, n = 11, group II; age 39.4 +/- 4.3, n = 12) were enrolled in an 8-week trial of LF-SQ blended cream in a randomized, matched pair double-blind study. The LF-SQ cream was applied twice daily on the right or left half of the face, and squalane blended cream (without fullerene-C60) was applied as the placebo on another half of the face. As clinical evaluations of wrinkle grades, visual observation and photographs, and silicone replicas of both crow's feet areas were taken at baseline (0 week) and at 4th and 8th weeks. Skin replicas were analyzed using an optical profilometry technique. The wrinkle and skin-surface roughness features were calculated and statistically analyzed. Subsequently, trans-epidermal water loss (TEWL), moisture levels of the stratum corneum, and visco-elasticity (suppleness: RO and elasticity: R7) were measured on cheeks by instrumental analysis. LF-SQ cream enhanced the skin moisture and the anti-wrinkle formation. LF-SQ cream that was applied on a face twice daily was not effective at 4th week, but significantly more effective than the placebo at 8th week (p < 0.05) without severe side effects. The roughness-area ratio showed significant improvement (p < 0.05) at 8th week with LF-SQ cream as compared to 0 week with LF-SQ cream, but no significant difference was detected between LF-SQ cream and the placebo. We suggest that LF-SQ could be used as an active ingredient for wrinkle-care cosmetics.

  19. Tunable electronic properties of a proton-responsive N,N-dimethylaminoazobenzene fullerene (C60) dyad.

    PubMed

    Kumar, K Senthil; Patnaik, Archita

    2010-12-01

    A basic N,N-dimethylaminoazobenzene-fullerene (C(60)) dyad molecular skeleton is modelled and synthesized. In spite of the myriad use of azobenzene as a photo- and electrochromic moiety, the idea presented herein is to adopt a conceptually different path by using it as a bridge in a donor-bridge-acceptor single-molecular skeleton, connecting the electron acceptor N-methylfulleropyrrolidine with an electron donor N,N-dimethylaniline. Addition of trifluoroacetic acid (TFA) results in a drastic colour change of the dyad from yellow to pink in dichloromethane (DCM). The structure of the protonated species are established from electronic spectroscopy and time-dependent density functional theory (TD-DFT) calculations. UV/Vis spectroscopic investigations reveal the disappearance of the 409 nm (1)(π→π*) transition with appearance of new features at 520 and 540 nm, attributed to protonated β and α nitrogens, respectively, along with a finite weight of the C(60) pyrrolidinic nitrogen. Calculations reveal intermixing of n((N=N))→π*((N=N)) and charge transfer (CT) transitions in the neutral dyad, whereas, the n((N=N))→π*((N=N)) transition in the protonated dyad is buried under the dominant (1)(π →π*) feature and is red-shifted upon Gaussian deconvolution. The experimental binding constants involved in the protonation of N,N-dimethylanilineazobenzene and the dyad imply an almost equal probability of existence of both α- and β-protonated forms. Larger binding constants for the protonated dyads imply more stable dyad complexes than for the donor counterparts. One of the most significant findings upon protonation resulted in frontier molecular orbital (FMO) switching with the dyad LUMO located on the donor part, evidenced from electrochemical investigations. The appearance of a new peak, prior to the first reduction potential of N-methylfulleropyrrolidine, clearly indicates location of the first incoming electron on the donor-centred LUMO of the dyad

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

    NASA Astrophysics Data System (ADS)

    Li, Liwei

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

  1. Photo excitation and laser detachment of C60(-) anions in a storage ring.

    PubMed

    Støchkel, K; Andersen, J U

    2013-10-28

    We have studied the photo physics of C60(-) anions in the electrostatic storage ring ELISA with ions produced in a plasma source and cooled and bunched in a He filled ion trap. A previous study using delayed electron detachment as a signal of resonance-enhanced multiphoton electron detachment (REMPED) has been repeated both at room temperature and with the trap cooled to liquid nitrogen temperature. However, wavelength dependence of the overlap of the strongly focused laser beam with the ion beam introduces distortions of the absorption spectrum. We have therefore applied a new method, combining the IR light with a slightly delayed, powerful UV pulse (266 nm). After absorption of three UV photons, the ions decay by delayed (thermal) electron emission, and time spectra are recorded for varying wavelength. The fraction of ions heated by absorption of a single IR photon is then extracted from a principal component analysis of these spectra. In good agreement with the earlier REMPED experiment, an origin band for transitions between the two lowest electronic levels of the anion, with t1u and t1g symmetry, is observed at 9380 cm(-1), with strong sidebands from excitation of the two A(g) and eight H(g) vibrations. As before, a hot band is observed at about 9150 cm(-1) and assigned to a transition from an excited vibronic Jahn-Teller state. However, an earlier observed band at higher energy, interpreted as a transition from this excited state to an excited vibronic state in the t1g electronic level, is much weaker in the new measurements and could be an H(g) vibrational sideband. Also earlier studies of direct laser detachment from C60(-) in the storage ring ASTRID have been revisited, with ions cooled by liquid nitrogen in the ion trap. We confirm the previous measurement with a determination of the threshold for s-wave detachment at 2.664 ± 0.005 eV, slightly lower than a recent value of the electron binding, 2.683 ± 0.008 eV, obtained from the energy spectrum of

  2. Chemistry, Creativity, Collaboration, and C60: An Interview with Harold W. Kroto

    NASA Astrophysics Data System (ADS)

    Cardellini, Liberato

    2005-05-01

    This interview offers a sketch of the story of Harold Kroto’s scientific life, highlighting his research activities and discoveries. Illustrative examples include Kroto's study of electronic spectra of molecules, the synthesis of phosphoalkenes and phosphoalkynes, the study of long carbon chain molecules in the lab, and the search for long carbon chain molecules in the interstellar medium while at Rice University that led to the serendipitous discovery of fullerene. Kroto defends and stresses the importance of fundamental research and the role of scientists in society; he also suggests a way to foster children's interest in science.

  3. Effect of surfactants on the removal and acute toxicity of aqueous nC60 aggregates in water treatment process.

    PubMed

    Ge, Ling; Kirumba, George; Zhang, Bo; Pal, Amrita; He, Yiliang

    2015-07-01

    This work aimed to evaluate the effect of surfactants on the removal of aqueous nC60 aggregates by coagulation-filtration process and assess the acute toxicity of filtrates by Microtox test. Three surfactants including cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100 (TX100) were selected representing cationic, anionic, and nonionic types, respectively. Results showed that the change of physicochemical properties of nC60 associating with different types of surfactants determined nC60's removal efficiency and acute toxicity. CTAB increased the number of large particles. It also changed the zeta potential of nC60 from negative to positive, leading to the low removal rates (17.3-50.2%) when CTAB concentration was designed in the range of 0.03-1 g/L, and the filtrates showed acute toxicity to bioluminescent bacteria (inhibition rate > 80%). On the contrary, TX100 obviously increased the proportion of small particles, and it is noteworthy that even less than 1 mg/L of nC60 (20% of the initial concentration) with TX100 remaining in filtrates could evoke phototoxicity due to reactive oxygen species (ROS) generation under UV irradiation. Compared to CTAB and TX100, SDS exerted an effect on the removal process and toxicity of nC60 only when concentration was beyond the critical micelle concentration (CMC; 2.5 g/L). These findings collectively suggest that characteristics of nC60 are flexible and strongly dependent on surfactant modification, as a result of which these particles could potentially find their way through water treatment route and exert a potential toxicity risk.

  4. Synthesis of mono-dispersed nano-scale fullerene (C60) crystals.

    PubMed

    Bae, Eunjoo; Kwak, Byoung Kyu; Kim, Woo-Sik; Kim, Younghun; Choi, Kyunghee; Yil, Jongheop

    2011-04-01

    Fullerene (C60), which has a unique molecular structure, was used in the preparation of crystalline organic nano-crystals. Fullerene was dissolved in toluene and this fullerene solution was mixed with water drastically. During this process, fullerene transferred from toluene to water phase. The significantly different solubility of fullerene in a toluene/water solvent system played an important role in the self-assembly of single fullerene nano-crystals, as it is called drowning-out crystallization. In addition, pH of water was controlled to carry out the interfacial transference of fullerene. An optical spectrum analysis showed that the fullerene was transferred by a hydrolysis reaction from toluene to water, depending on the pH and toluene involved in the crystal structure. During the interfacial transference, the growth of nano-scale fullerene occurred at pH > 7. Importantly, fullerene nanocrystals were formed with a mono-dispersed square structure on a nano-scale (104 nm average size and 1.03 +/- 0.24 aspect ratio) at pH 10.

  5. Electronic and magnetic properties of endohedrally doped fullerene Mn@C(60): a total energy study.

    PubMed

    Li, Guangping; Sabirianov, R F; Lu, Jing; Zeng, X C; Mei, W N

    2008-02-21

    We perform total energy calculations on a manganese atom encapsulated inside a C(60) cage using density functional theory with the generalized gradient approximation through three optimization schemes and along four paths inside the cage. We find that when Mn is located in the central region, its electronic and magnetic properties are not exactly the same as those of a free Mn atom due to weak coupling between Mn and the cage. As Mn is shifted toward to the edge, the total energy and spin start to change significantly when Mn is situated about one-third of the way between the cage center and edge, and the total energy reaches a local minimum. Finally the interaction between Mn and the cage turns repulsive as Mn approaches the edge. We also find that, along the lowest energy path, there exist three consecutive local energy minima and each of these has a different spin M. The ground state has the lowest M=3, Mn is located about 1.6 A away from the cage center, and the binding energy is 0.08 eV. We attribute the decrease in total energy and spin to Mn and C hybridization.

  6. Determining the Origin of Half-bandgap-voltage Electroluminescence in Bifunctional Rubrene/C60 Devices

    NASA Astrophysics Data System (ADS)

    Chen, Qiusong; Jia, Weiyao; Chen, Lixiang; Yuan, De; Zou, Yue; Xiong, Zuhong

    2016-05-01

    Lowering the driving voltage of organic light-emitting diodes (OLEDs) is an important approach to reduce their energy consumption. We have fabricated a series of bifunctional devices (OLEDs and photovoltaics) using rubrene and fullerene (C60) as the active layer, in which the electroluminescence threshold voltage(~1.1 V) was half the value of the bandgap of rubrene. Magneto-electroluminescence (MEL) response of planner heterojunction diodes exhibited a small increase in response to a low magnetic field strength (<20 mT) however, a very large decay was observed at a high magnetic field strength (>20 mT). When a hole-transport layer with a low mobility was included in these devices, the MEL response reversed in shape, and simultaneously, the EL threshold voltage became larger than the bandgap voltage. When bulk heterojunction device was examined, the amplitude of MEL curves presented an anomalous voltage-dependence. Following an analysis of the MEL responses of these devices, we proposed that the EL of half-bandgap-voltage device originated from bimolecular triplet-triplet annihilation in the rubrene film, rather than from singlet excitons that formed via an interface auger recombination. This work provides critical insight into the mechanisms of OLED emission and will help advance the applications of bifunctional devices.

  7. Tight-binding molecular dynamics simulations of radiation-induced C60 fragmentation

    NASA Astrophysics Data System (ADS)

    Beu, Titus A.; Horváth, Lóránd; Ghişoiu, Ioan

    2009-02-01

    The radiation-induced fragmentation of the C60 fullerene was investigated by tight-binding molecular dynamics simulations based on the parametrization of Papaconstantopoulos [Tight-Binding Approach to Computational Materials Science, edited by P.E.A. Turchi, A. Gonis, and L. Colombo, M.R.S. Symposia Proceedings No. 491 (Materials Research Society, Pittsburgh, 1998), p. 221] and employing novel models for nonadiabatic excitation and charge redistribution. The resulted fragment size and fragment charge distributions, averaged over large ensembles of trajectories corresponding to total ionization states up to +24e and excitation energies up to 1000 eV, have been used to analyze the fragmentation statistics in terms of several derived quantities. For moderate excitation energies, the fragment size profiles reproduce the experimentally observed U shape and bimodal dependence. Even though for high excitation energies and high total charges, predominantly multifragmentation occurs, a genuine power-law dependence sets in only beyond 1000 eV. A well-defined phase-transition region is found in the total charge-excitation energy plane, which appears to be delimited by a roughly parabolic critical line. The overall average critical excitation energy estimated from the simulations amounts to 55 eV and agrees with the experimental findings.

  8. Determining the Origin of Half-bandgap-voltage Electroluminescence in Bifunctional Rubrene/C60 Devices

    PubMed Central

    Chen, Qiusong; Jia, Weiyao; Chen, Lixiang; Yuan, De; Zou, Yue; Xiong, Zuhong

    2016-01-01

    Lowering the driving voltage of organic light-emitting diodes (OLEDs) is an important approach to reduce their energy consumption. We have fabricated a series of bifunctional devices (OLEDs and photovoltaics) using rubrene and fullerene (C60) as the active layer, in which the electroluminescence threshold voltage(~1.1 V) was half the value of the bandgap of rubrene. Magneto-electroluminescence (MEL) response of planner heterojunction diodes exhibited a small increase in response to a low magnetic field strength (<20 mT); however, a very large decay was observed at a high magnetic field strength (>20 mT). When a hole-transport layer with a low mobility was included in these devices, the MEL response reversed in shape, and simultaneously, the EL threshold voltage became larger than the bandgap voltage. When bulk heterojunction device was examined, the amplitude of MEL curves presented an anomalous voltage-dependence. Following an analysis of the MEL responses of these devices, we proposed that the EL of half-bandgap-voltage device originated from bimolecular triplet-triplet annihilation in the rubrene film, rather than from singlet excitons that formed via an interface auger recombination. This work provides critical insight into the mechanisms of OLED emission and will help advance the applications of bifunctional devices. PMID:27142285

  9. Aromatic tripodal receptors for (C(60)-I(h))[5,6]fullerene.

    PubMed

    Dell'Anna, Gian Maria; Annunziata, Rita; Benaglia, Maurizio; Celentano, Giuseppe; Cozzi, Franco; Francesconi, Oscar; Roelens, Stefano

    2009-09-21

    Monotopic and ditopic tripodal benzene platforms featuring aromatic and perfluoroaromatic side-arms have been synthesized, and their binding properties toward C(60)-fullerene have been investigated by HPLC examining retention times on a fullerene-modified silica stationary phase, using highly polar eluants (acetonitrile and acetonitrile/water). By comparison of structurally homogeneous sets of receptors, a clear trend could be found, pointing to an increased retention for ditopic derivatives, in which binding can occur on both sides of the benzene platform, over their monotopic counterparts. Among the latter, monotopic receptors containing H-substituted aromatic residues showed stronger retention than their perfluorinated analogues. This effect was ascribed to the greater availability of the pi-electrons in a H-substituted aromatic ring with respect to the corresponding F-substituted counterpart in participating in a pi-pi interaction with the electron-poor surface of fullerene. Several NMR experiments aimed to investigate binding interactions in solution, using the much less polar solvents required by the fullerene solubility (1,1,2,2-tetrachloroethane, chloroform, toluene, and CS(2)), did not provide any evidence of binding interactions. We concluded that pi-pi interactions between fullerene and the investigated flexible tripodal receptors cannot compete with solvation in poorly polar solvents, and that the binding interactions observed by HPLC were essentially forced by the strongly polar eluant employed for the HPLC analysis.

  10. Simple synthetic method toward solid supported c60 visible light-activated photocatalysts.

    PubMed

    Moor, Kyle J; Kim, Jae-Hong

    2014-01-01

    Solid supported fullerene materials are prepared in aims of creating a fullerene-based photocatalyst that is capable of producing (1)O2 in the aqueous phase. Past studies of using fullerene as a photocatalyst in water have exclusively focused on using water soluble fullerene derivatives and employed sophisticated chemistry to create immobilized fullerene materials. The method presented herein is much less synthetically complex and utilizes pristine fullerene, providing a drastically simpler route to supported fullerene materials and furthering their potential for use in environmental applications. Covalent immobilization was achieved through the nucleophilic addition of a terminal amine (located on a solid support) across a [6,6] fullerene double bond, resulting in attachment directly to C60's cage. Immobilization allowed supported fullerene moieties to produce (1)O2 in water under various illumination conditions and inactivate MS2 bacteriophages. In a water with natural organic matter, supported fullerene materials produced (1)O2 under visible light irradiation without exhibiting significant loss of photocatalytic activity after successive cycling.

  11. Determining the Origin of Half-bandgap-voltage Electroluminescence in Bifunctional Rubrene/C60 Devices.

    PubMed

    Chen, Qiusong; Jia, Weiyao; Chen, Lixiang; Yuan, De; Zou, Yue; Xiong, Zuhong

    2016-01-01

    Lowering the driving voltage of organic light-emitting diodes (OLEDs) is an important approach to reduce their energy consumption. We have fabricated a series of bifunctional devices (OLEDs and photovoltaics) using rubrene and fullerene (C60) as the active layer, in which the electroluminescence threshold voltage(~1.1 V) was half the value of the bandgap of rubrene. Magneto-electroluminescence (MEL) response of planner heterojunction diodes exhibited a small increase in response to a low magnetic field strength (<20 mT); however, a very large decay was observed at a high magnetic field strength (>20 mT). When a hole-transport layer with a low mobility was included in these devices, the MEL response reversed in shape, and simultaneously, the EL threshold voltage became larger than the bandgap voltage. When bulk heterojunction device was examined, the amplitude of MEL curves presented an anomalous voltage-dependence. Following an analysis of the MEL responses of these devices, we proposed that the EL of half-bandgap-voltage device originated from bimolecular triplet-triplet annihilation in the rubrene film, rather than from singlet excitons that formed via an interface auger recombination. This work provides critical insight into the mechanisms of OLED emission and will help advance the applications of bifunctional devices. PMID:27142285

  12. Quasi-ordered C60 molecular films grown on the pseudo-ten-fold (1 0 0) surface of the Al13Co4 quasicrystalline approximant.

    PubMed

    Fournée, V; Gaudry, É; Ledieu, J; de Weerd, M-C; Diehl, R D

    2016-09-01

    The growth of C60 films on the pseudo-ten-fold (1 0 0) surface of the orthorhombic Al13Co4 quasicrystalline approximant was studied experimentally by scanning tunneling microscopy, low-energy electron diffraction and photoemission spectroscopy. The (1 0 0) surface terminates at bulk-planes presenting local atomic configurations with five-fold symmetry-similar to quasicrystalline surfaces. While the films deposited at room temperature were found disordered, high-temperature growth (up to 693 K) led to quasi-ordered molecular films templated on the substrate rectangular unit mesh. The most probable adsorption sites and geometries were investigated by density functional theory (DFT) calculations. A large range of adsorption energies was determined, influenced by both symmetry and size matching at the molecule-substrate interface. The quasi-ordered structure of the film can be explained by C60 adsorption at the strongest adsorption sites which are too far apart compared to the distance minimizing the intermolecular interactions, resulting in some disorder in the film structure at a local scale. Valence band photoemission indicates a broadening of the molecular orbitals resulting from hybridization between the substrate and overlayer electronic states. Dosing the film at temperature above 693 K led to molecular damage and formation of carbide thin films possessing no azimuthal order with respect to the substrate. PMID:27365317

  13. Quasi-ordered C60 molecular films grown on the pseudo-ten-fold (1 0 0) surface of the Al13Co4 quasicrystalline approximant

    NASA Astrophysics Data System (ADS)

    Fournée, V.; Gaudry, É.; Ledieu, J.; de Weerd, M.-C.; Diehl, R. D.

    2016-09-01

    The growth of C60 films on the pseudo-ten-fold (1 0 0) surface of the orthorhombic Al13Co4 quasicrystalline approximant was studied experimentally by scanning tunneling microscopy, low-energy electron diffraction and photoemission spectroscopy. The (1 0 0) surface terminates at bulk-planes presenting local atomic configurations with five-fold symmetry—similar to quasicrystalline surfaces. While the films deposited at room temperature were found disordered, high-temperature growth (up to 693 K) led to quasi-ordered molecular films templated on the substrate rectangular unit mesh. The most probable adsorption sites and geometries were investigated by density functional theory (DFT) calculations. A large range of adsorption energies was determined, influenced by both symmetry and size matching at the molecule-substrate interface. The quasi-ordered structure of the film can be explained by C60 adsorption at the strongest adsorption sites which are too far apart compared to the distance minimizing the intermolecular interactions, resulting in some disorder in the film structure at a local scale. Valence band photoemission indicates a broadening of the molecular orbitals resulting from hybridization between the substrate and overlayer electronic states. Dosing the film at temperature above 693 K led to molecular damage and formation of carbide thin films possessing no azimuthal order with respect to the substrate.

  14. Radioactive decay speedup at T=5 K: electron-capture decay rate of (7)Be encapsulated in C(60).

    PubMed

    Ohtsuki, T; Ohno, K; Morisato, T; Mitsugashira, T; Hirose, K; Yuki, H; Kasagi, J

    2007-06-22

    The electron-capture (EC) decay rate of (7)Be in C(60) at the temperature of liquid helium (T=5 K) was measured and compared with the rate in Be metal at T=293 K. We found that the half-life of (7)Be in endohedral C(60) ((7)Be@C(60)) at a temperature close to T=5 K is 52.47+/-0.04 d, a value that is 0.34% faster than that at T=293 K. In this environment, the half-life of (7)Be is nearly 1.5% faster than that inside Be metal at room temperature (T=293 K). We then interpreted our observations in terms of calculations of the electron density at the (7)Be nucleus position inside the C(60); further, we estimate theoretically the temperature dependence (at T=0 K and 293 K) of the electron density at the Be nucleus position in the stable center inside C(60). The theoretical estimates were almost in agreement with the experimental observations.

  15. The happy marriage between electron-phonon superconductivity and Mott physics in Cs3C60: A first-principle phase diagram

    NASA Astrophysics Data System (ADS)

    Capone, Massimo; Nomura, Yusuke; Sakai, Shiro; Giovannetti, Gianluca; Arita, Ryotaro

    The phase diagram of doped fullerides like Cs3C60 as a function of the spacing between fullerene molecules is characterized by a first-order transition between a Mott insulator and an s-wave superconductor with a dome-shaped behavior of the critical temperature. By means of an ab-initio modeling of the bandstructure, the electron-phonon interaction and the interaction parameter and a Dynamical Mean-Field Theory solution, we reproduce the phase diagram and demonstrate that phonon superconductivity benefits from strong correlations confirming earlier model predictions. The role of correlations is manifest also in infrared measurements carried out by L. Baldassarre. The superconducting phase shares many similarities with ''exotic'' superconductors with electronic pairing, suggesting that the anomalies in the ''normal'' state, rather than the pairing glue, can be the real common element unifying a wide family of strongly correlated superconductors including cuprates and iron superconductors

  16. Fourier photospectroscopy of Xe@C60 in the Xe 4d giant resonance region: Testing the single-photoionization theory against recent measurements

    NASA Astrophysics Data System (ADS)

    Patel, Aakash; Chakraborty, Himadri

    2012-06-01

    We have developed a technique, based on Fourier-transforming cross sections to the reciprocal configuration space, to explore the electronic multiple interferences in the photoionization of endohedral fullerene molecules. Using this technique, the single photoionization cross section of endohedral Xe@C60 over Xe 4d giant resonance energy region, calculated in the time dependent local density approximation (TDLDA), is compared with recent double photoionization experimental data [1]. The analysis of oscillatory cross sections derives a number of inherent similarities between the prediction and the data, including a large beating-type oscillation and several others of intermediate size [2]. Results stress the need for more accurate measurements to access the wealth of information about the geometry of the system.[4pt] [1] A.L.D. Kilcoyne et al., Phys. Rev. Lett. 105, 213001 (2010);[0pt] [2] A.B. Patel and H.S. Chakraborty, J. Phys. B Fast Track Comm. 44, 191001 (2011).

  17. Chemical physics behind formation of effective and selective non-covalent interaction between fullerenes (C60 and C70) and a designed chiral monoporphyrin in solution

    NASA Astrophysics Data System (ADS)

    Ray, Anamika; Banerjee, Shrabanti; Bauri, Ajoy K.; Bhattacharya, Sumanta

    2016-02-01

    The present letter extricates the chemical physics behind non-covalent interaction between fullerenes (C60 and C70) and a designed chiral monoporphyrin molecule (1) in toluene. Steady state fluorescence studies on complex formation reveal higher binding constant (K) for C70/1 complex, i.e., K = 16,020 dm3 mol-1, and very good selectivity of binding, viz., KC70/1/KC60/1 ∼ 10.0. Time-resolved fluorescence study elicits role of static quenching mechanism behind photoexcited decay of 1* in presence of fullerene. Density functional theoretical calculations in vacuo validates the strong complexation between C70 and 1 and establishes the side-on binding motif of C70 towards 1 during complexation.

  18. Communication: Quantum six-dimensional calculations of the coupled translation-rotation eigenstates of H2O@C60

    NASA Astrophysics Data System (ADS)

    Felker, Peter M.; Bačić, Zlatko

    2016-05-01

    We report rigorous quantum calculations of the translation-rotation (TR) eigenstates of para- and ortho-H2O@C60. They provide a comprehensive description of the dynamical behavior of H2O inside the fullerene having icosahedral (Ih) symmetry. The TR eigenstates are assigned in terms of the irreducible representations of the proper symmetry group of H2O@C60, as well as the appropriate translational and rotational quantum numbers. The coupling between the orbital and the rotational angular momenta of the caged H2O gives rise to the total angular momentum λ, which additionally labels each TR level. The calculated TR levels allow tentative assignments of a number of transitions in the recent experimental INS spectra of H2O@C60 that have not been assigned previously.

  19. Communication: Quantum six-dimensional calculations of the coupled translation-rotation eigenstates of H2O@C60.

    PubMed

    Felker, Peter M; Bačić, Zlatko

    2016-05-28

    We report rigorous quantum calculations of the translation-rotation (TR) eigenstates of para- and ortho-H2O@C60. They provide a comprehensive description of the dynamical behavior of H2O inside the fullerene having icosahedral (Ih) symmetry. The TR eigenstates are assigned in terms of the irreducible representations of the proper symmetry group of H2O@C60, as well as the appropriate translational and rotational quantum numbers. The coupling between the orbital and the rotational angular momenta of the caged H2O gives rise to the total angular momentum λ, which additionally labels each TR level. The calculated TR levels allow tentative assignments of a number of transitions in the recent experimental INS spectra of H2O@C60 that have not been assigned previously.

  20. Cesium doping at C60/rubrene heterointerfaces for improving the performance of organic light- and current-generating devices

    NASA Astrophysics Data System (ADS)

    Cheng, Chiu-Ping; Lu, Meng-Han; Chu, Yu-Ya; Wei, Ching-Hsuan; Pi, Tun-Wen

    2015-01-01

    This study examined the effect of adding cesium (Cs) at C60/rubrene heterointerfaces by using synchrotron-radiation photoelectron spectroscopy. A C60/rubrene heterostructure is the basis of a novel organic dual device found to facilitate efficient integration of both electroluminescent and photovoltaic functions. With Cs doping, the interfacial dipole potential was considerably enlarged, as was the separation between the lowest unoccupied molecular orbital of C60 and the highest occupied molecular orbital of rubrene. However, the energy-level diagram indicated that a high Cs concentration prevents the formation of photoexcitons. By contrast, adding a small amount of Cs can effectively improve the efficiency of light- and current-generating devices. In particular, the deficiency of the dopants at the heterointerface may benefit the survival of photoexcitons.