The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
Richard Pincak - One of the best experts on this subject based on the ideXlab platform.
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Energy gap between highest occupied molecular orbital and lowest unoccupied molecular orbital in multiwalled Fullerenes
Physical Review A, 2009Co-Authors: M. Pudlak, Richard PincakAbstract:We report on the electronic structure of the C60-C240 multiwalled Fullerene onion near the Fermi level. The analytical expressions for the hybridizations of the orbitals on the Fullerene shells were derived. The difference between the Fermi levels of individual Fullerenes is obtained. The highest occupied molecular orbital– lowest unoccupied molecular orbital energy gap for the C60-C240 Carbon Fullerene onion is calculated. The charge transfer from the outer shell to the inner shell in the base state of the onion is determined. Splitting and the shift of the energy levels of the onion as a result of intershell interaction are predicted.
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Energy gap between highest occupied molecular orbital and lowest unoccupied molecular orbital in multiwalled Fullerenes
Physical Review A, 2009Co-Authors: M. Pudlak, Richard PincakAbstract:We report on the electronic structure of the ${\text{C}}_{60}{\text{-C}}_{240}$ multiwalled Fullerene (onion) near the Fermi level. The analytical expressions for the hybridizations of the $\ensuremath{\pi}$ orbitals on the Fullerene shells were derived. The difference between the Fermi levels of individual Fullerenes is obtained. The highest occupied molecular orbital--lowest unoccupied molecular orbital energy gap for the ${\text{C}}_{60}{\text{-C}}_{240}$ Carbon Fullerene onion is calculated. The charge transfer from the outer shell to the inner shell in the base state of the onion is determined. Splitting and the shift of the energy levels of the onion as a result of intershell interaction are predicted.
Yoshihiko Kurui - One of the best experts on this subject based on the ideXlab platform.
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Conductance Measurement of a Single Carbon Fullerene Suspended between Two Gold (111) Facets
Japanese Journal of Applied Physics, 2009Co-Authors: Yoshifumi Oshima, Makoto Yoshida, Yoshihiko KuruiAbstract:We succeeded in sandwiching a single Carbon Fullerene between two (111) facets and measured the conductance at room temperature using a transmission electron microscope combined with a scanning tunneling microscope. The Carbon Fullerene prevented to move around at the gap when it was slightly compressed between two facets. In this condition, the C80 and C140 Fullerenes had the values of 0.53 and 0.62G0 (=2e2/h), respectively, and sometime showed stepwise conductance change due to rotation. Since current–voltage characteristics showed metallic behavior for the C140 Fullerene, the single Carbon Fullerene is thought to have metallic bonds to gold (111) surface under a slight compression, resulting in keeping the same adsorption site.
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Direct Observation of a Single Carbon Fullerene Transfer
Applied Physics Express, 2008Co-Authors: Yoshifumi Oshima, Yoshihiko KuruiAbstract:We directly observed the transfer of a single 1.1-nm-diameter Carbon Fullerene between two gold electrodes separated by about 1.8 nm by applying a bias voltage of 0.6 V. The conductance showed sharp spikes of the order of 10-1G0 (=2e2/h) at the moment of transfer, which was on the order of those obtained when the Fullerene bridged the two electrodes. No such transfer was observed at 0.1 V. We believe that the Fullerene transfers at the moment when it has expanded, due to polarization, to the extent that it bridges the two electrodes under a high electric field.
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In-Situ Observation of the Fabrication Process of a Single Shell Carbon Fullerene Nano-Contact Using Transmission Electron Microscope–Scanning Tunneling Microscope
Japanese Journal of Applied Physics, 2007Co-Authors: Makoto Yoshida, Yoshifumi Oshima, Yoshihiko Kurui, Kunio TakayanagiAbstract:A single shell Carbon Fullerene (SSF) was fabricated from an amorphous Carbon agglomerate (a-C agglomerate) suspended between two gold electrodes. As the applied bias voltage to the a-C agglomerate was increased using a transmission electron microscope–scanning tunneling microscope (TEM–STM) system, the transformation into the SSF via a glassy Carbon was observed. It was found that the SSF transformation occurred above the bias voltage of 0.6 V without a prominent loss of the number of Carbon atoms. The size of the SSFs ranged from C60 to C620 having Ih or I symmetry.
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Deformation of a Single Carbon Fullerene Suspended between Electrodes with a Narrow Gap
Hyomen Kagaku, 2007Co-Authors: Yoshifumi Oshima, Makoto Yoshida, Yoshihiko KuruiAbstract:We developed a conductance measurement system of a single Carbon Fullerene simultaneously with a transmission electron microscope (TEM) observation. A single Carbon Fullerene was made from an agglomerate of Carbon atoms suspended between both gold electrodes. When the bias voltage above 0.6 V was applied between both electrodes, the transformation into a single Carbon Fullerene was observed. We measured electrical conductance of the single Carbon Fullerene adsorbed on the electrode surface in the process of bringing the opposite side electrode close to it. The conductance showed tunneling behavior from 10−5 to 10−2 G0 (= 2e2/h ; quantized unit of conductance) and abruptly jumped to 0.5 G0. TEM observation showed that an ellipsoidal Carbon Fullerene expanded along the normal direction to the electrode surface and had a contact with the electrode, which corresponded to the conductance jump. The conductance value of the Fullerene was 0.5-0.6 G0.
M. Pudlak - One of the best experts on this subject based on the ideXlab platform.
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Energy gap between highest occupied molecular orbital and lowest unoccupied molecular orbital in multiwalled Fullerenes
Physical Review A, 2009Co-Authors: M. Pudlak, Richard PincakAbstract:We report on the electronic structure of the C60-C240 multiwalled Fullerene onion near the Fermi level. The analytical expressions for the hybridizations of the orbitals on the Fullerene shells were derived. The difference between the Fermi levels of individual Fullerenes is obtained. The highest occupied molecular orbital– lowest unoccupied molecular orbital energy gap for the C60-C240 Carbon Fullerene onion is calculated. The charge transfer from the outer shell to the inner shell in the base state of the onion is determined. Splitting and the shift of the energy levels of the onion as a result of intershell interaction are predicted.
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Energy gap between highest occupied molecular orbital and lowest unoccupied molecular orbital in multiwalled Fullerenes
Physical Review A, 2009Co-Authors: M. Pudlak, Richard PincakAbstract:We report on the electronic structure of the ${\text{C}}_{60}{\text{-C}}_{240}$ multiwalled Fullerene (onion) near the Fermi level. The analytical expressions for the hybridizations of the $\ensuremath{\pi}$ orbitals on the Fullerene shells were derived. The difference between the Fermi levels of individual Fullerenes is obtained. The highest occupied molecular orbital--lowest unoccupied molecular orbital energy gap for the ${\text{C}}_{60}{\text{-C}}_{240}$ Carbon Fullerene onion is calculated. The charge transfer from the outer shell to the inner shell in the base state of the onion is determined. Splitting and the shift of the energy levels of the onion as a result of intershell interaction are predicted.
Yoshifumi Oshima - One of the best experts on this subject based on the ideXlab platform.
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Conductance Measurement of a Single Carbon Fullerene Suspended between Two Gold (111) Facets
Japanese Journal of Applied Physics, 2009Co-Authors: Yoshifumi Oshima, Makoto Yoshida, Yoshihiko KuruiAbstract:We succeeded in sandwiching a single Carbon Fullerene between two (111) facets and measured the conductance at room temperature using a transmission electron microscope combined with a scanning tunneling microscope. The Carbon Fullerene prevented to move around at the gap when it was slightly compressed between two facets. In this condition, the C80 and C140 Fullerenes had the values of 0.53 and 0.62G0 (=2e2/h), respectively, and sometime showed stepwise conductance change due to rotation. Since current–voltage characteristics showed metallic behavior for the C140 Fullerene, the single Carbon Fullerene is thought to have metallic bonds to gold (111) surface under a slight compression, resulting in keeping the same adsorption site.
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Direct Observation of a Single Carbon Fullerene Transfer
Applied Physics Express, 2008Co-Authors: Yoshifumi Oshima, Yoshihiko KuruiAbstract:We directly observed the transfer of a single 1.1-nm-diameter Carbon Fullerene between two gold electrodes separated by about 1.8 nm by applying a bias voltage of 0.6 V. The conductance showed sharp spikes of the order of 10-1G0 (=2e2/h) at the moment of transfer, which was on the order of those obtained when the Fullerene bridged the two electrodes. No such transfer was observed at 0.1 V. We believe that the Fullerene transfers at the moment when it has expanded, due to polarization, to the extent that it bridges the two electrodes under a high electric field.
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In-Situ Observation of the Fabrication Process of a Single Shell Carbon Fullerene Nano-Contact Using Transmission Electron Microscope–Scanning Tunneling Microscope
Japanese Journal of Applied Physics, 2007Co-Authors: Makoto Yoshida, Yoshifumi Oshima, Yoshihiko Kurui, Kunio TakayanagiAbstract:A single shell Carbon Fullerene (SSF) was fabricated from an amorphous Carbon agglomerate (a-C agglomerate) suspended between two gold electrodes. As the applied bias voltage to the a-C agglomerate was increased using a transmission electron microscope–scanning tunneling microscope (TEM–STM) system, the transformation into the SSF via a glassy Carbon was observed. It was found that the SSF transformation occurred above the bias voltage of 0.6 V without a prominent loss of the number of Carbon atoms. The size of the SSFs ranged from C60 to C620 having Ih or I symmetry.
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Deformation of a Single Carbon Fullerene Suspended between Electrodes with a Narrow Gap
Hyomen Kagaku, 2007Co-Authors: Yoshifumi Oshima, Makoto Yoshida, Yoshihiko KuruiAbstract:We developed a conductance measurement system of a single Carbon Fullerene simultaneously with a transmission electron microscope (TEM) observation. A single Carbon Fullerene was made from an agglomerate of Carbon atoms suspended between both gold electrodes. When the bias voltage above 0.6 V was applied between both electrodes, the transformation into a single Carbon Fullerene was observed. We measured electrical conductance of the single Carbon Fullerene adsorbed on the electrode surface in the process of bringing the opposite side electrode close to it. The conductance showed tunneling behavior from 10−5 to 10−2 G0 (= 2e2/h ; quantized unit of conductance) and abruptly jumped to 0.5 G0. TEM observation showed that an ellipsoidal Carbon Fullerene expanded along the normal direction to the electrode surface and had a contact with the electrode, which corresponded to the conductance jump. The conductance value of the Fullerene was 0.5-0.6 G0.
R. A. Guirado-lópez - One of the best experts on this subject based on the ideXlab platform.
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Endohedral nitrogen storage in Carbon Fullerene structures: Physisorption to chemisorption transition with increasing gas pressure
The Journal of chemical physics, 2009Co-Authors: R. E. Barajas-barraza, R. A. Guirado-lópezAbstract:We present extensive pseudopotential density functional theory (DFT) calculations in order to analyze the structural properties and chemical reactivity of nitrogen molecules confined in spheroidal (C82) and tubelike (C110) Carbon Fullerene structures. For a small number of encapsulated nitrogens, the N2 species exist in a nonbonded state within the cavities and form well defined molecular conformations such as linear chains, zigzag arrays, as well as both spheroidal and tubular configurations. However, with increasing the number of stored molecules, the interaction among the confined nitrogens as well as between the N2 species and the Fullerene wall is not always mainly repulsive. Actually, at high densities of the encapsulated gas, we found both adsorption of N2 to the inner Carbon surface together with the formation of (N2)m molecular clusters. Total energy DFT calculations reveal that the shape of the interaction potential of a test molecule moving within the Carbon cavities strongly varies with the nu...
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Contrasting bonding behavior of thiol molecules on Carbon Fullerene structures
Physical Review A, 2003Co-Authors: J. C. Mixteco-sánchez, R. A. Guirado-lópezAbstract:We have performed semiempirical as well as ab initio density-functional theory (DFT) calculations at T =0 to analyze the equilibrium configurations and electronic properties of spheroidal C 6 0 as well as of cylindrical armchair (5,5) and (8,8) Fullerenes passivated with SCH 3 and S(CH 2 ) 2 CH 3 thiols. Our structural results reveal that the lowest-energy configurations of the adsorbates strongly depend on their chain length and on the structure of the underlying substrate. In the low-coverage regime, both SCH3 and S(CH 2 ) 2 CH 3 molecules prefer to organize into a molecular cluster on one side of the C 6 0 surface, providing thus a less protective organic coating for the Carbon structure. However, with increasing the number of adsorbed thiols, a transition to a more uniform distribution is obtained, which actually takes place for six and eight adsorbed molecules when using S(CH 2 ) 2 CH 3 and SCH 3 chains, respectively. In contrast, for the tubelike arrangements at the low-coverage regime, a quasi-one-dimensional zigzag organization of the adsorbates along the tubes is always preferred. The sulfur-Fullerene bond is considerably strong and is at the origin of outward and lateral displacements of the Carbon atoms, leading to the stabilization of three-membered rings on the surface (spheroidal structures) as well as to sizable nonuniform radial deformations (cylindrical configurations). The electronic spectrum of our thiol-passivated Fullerenes shows strong variations in the energy difference between the highest occupied and lowest unoccupied molecular orbitals as a function of the number and distribution of adsorbed thiols, opening thus the possibility to manipulate the transport properties of these compounds by means of selective adsorption mechanisms.