We have investigated the electronic‐state origin of the electrochemical capacitance of nanostructures by the ab initio calculations. We have chosen to study linear carbon chains and fullerenes encapsulating carbon cl...
We have investigated the electronic‐state origin of the electrochemical capacitance of nanostructures by the ab initio calculations. We have chosen to study linear carbon chains and fullerenes encapsulating carbon clusters. Linear carbon chains show a characteristic feature of the self‐capacitances depending on whether the number of atom is even or odd. The self‐capacitance of fullerenes significantly change as clusters inserted into the fullerene change. The essential cause for these variations of self‐capacitances comes mainly from the structure‐dependent properties of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies of carbon nanostructures.
We present our recent results on field emission from silicon clusters, graphitic ribbons, diamond surfaces, silicon surface and aluminum protrusions. The results are summarized.
We present our recent results on field emission from silicon clusters, graphitic ribbons, diamond surfaces, silicon surface and aluminum protrusions. The results are summarized.
Using femtosecond pulse-pair excitation at 800-nm, delay-time dependent adatom desorption from the Si(111)-7/spl times/7 surface was observed by scanning tunneling microscopy. Trends in the desorption yield and site s...
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Using femtosecond pulse-pair excitation at 800-nm, delay-time dependent adatom desorption from the Si(111)-7/spl times/7 surface was observed by scanning tunneling microscopy. Trends in the desorption yield and site selectivity were detected as a function of delay time.
Using femtosecond pulse-pair excitation at 800-nm, delay-time dependent adatom desorption from the Si(111)-7×7 surface was observed by scanning tunneling microscopy. Trends in the desorption yield and site select...
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Temperature dependence of photoconductivity has been investigated for single‐wall carbon nanotube (SWNT) films at 0.7eV in the temperature range from 10 K to room temperature (R.T.). Although photoresponse monotonous...
Temperature dependence of photoconductivity has been investigated for single‐wall carbon nanotube (SWNT) films at 0.7eV in the temperature range from 10 K to room temperature (R.T.). Although photoresponse monotonously increases with a decrease in temperature, the behavior depends on the sample. This sample dependence can be attributed to the variation of the transport properties of semiconducting‐SWNT circuits. We also relate the potential of photoconductivity measurements for evaluating NTs‐devices.
We investigated by theoretical calculations the electronic states and the transport properties of one of the oligoporphyrin molecular wires, the free-base tape-porphyrins. Inside these molecules the adjacent building ...
We investigated by theoretical calculations the electronic states and the transport properties of one of the oligoporphyrin molecular wires, the free-base tape-porphyrins. Inside these molecules the adjacent building blocks, referred to as porphyrin macrocycles, are linked by three conjugating C-C bonds aligned in parallel. We found that the origin of the extremely small highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gaps of these molecules is the strong coupling between the unoccupied π orbitals of each macrocycle. Then we considered the molecular bridges where these porphyrin molecules are bridged between the aluminum electrodes. We found that the conductances have large values and that the current increases nearly in proportion to the applied bias. These features are explained by the strong hybridization of the HOMO with the electrode wave functions and by the wide bandwidth of the tape porphyrins. Finally we studied the current distribution inside the tape-porphyrin wire. The current is found to flow in an anisotropic way, i.e., it seems to flow along the spatial distribution of the HOMO of the tape porphyrins, reflecting the strong hybridization of the HOMO with the electrode wave functions.
The unusual coexistence of two antiferromagnetic (AF) long-range orderings (LRO) in single-crystal NiS2 is investigated through measurements of inelastic neutron scattering, specific heat, uniform magnetic susceptibil...
The unusual coexistence of two antiferromagnetic (AF) long-range orderings (LRO) in single-crystal NiS2 is investigated through measurements of inelastic neutron scattering, specific heat, uniform magnetic susceptibility, and resistivity. Neutron scattering intensity reveals a honeycomb pattern of the intensity distribution in reciprocal lattice space (continuous-line structure along the Brillouin zone boundaries) in the extended critical temperature region (TN1=39.3K
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