Yuichi Shibuya

Bio: Yuichi Shibuya is an academic researcher from Toyo University. The author has an hindex of 1, co-authored 1 publications receiving 5 citations.

Formation and reinforcement of clusters composed of C60 molecules.

Abstract: We carry out two experiments: (1) the formation of clusters composed of C60 molecules via self-assembly and (2) the reinforcement of the clusters. Firstly, clusters such as fibres and helices composed of C60 molecules are produced via self-assembly in supercritical carbon dioxide. However, C60 molecules are so weakly bonded to each other in the clusters that the clusters are broken by the irradiation of electron beams during scanning electron microscope observation. Secondly, UV photons are irradiated inside a chamber in which air is filled at 1 atm and the above clusters are placed, and it was found that the clusters are reinforced; that is, they are not broken by electron beams any more. C60 molecules located at the surface of the clusters are oxidised, i.e. C60On molecules, where n = 1, 2, 3 and 4, are produced according to time-of-flight mass spectroscopy. It is supposed that oxidised C60 molecules at the surface of the clusters may have an important role for the reinforcement, but the actual mechanism of the reinforcement of the clusters has not yet been clearly understood and therefore is an open question.

Photochemistry of small molecules

Abstract: Photochemistry of Small Molecules. By Hideo Okabe. Pp. 431. (Wiley: Chichester, UK, and New York, 1978.) £24.55.

Suppression of Drain-Induced Barrier Lowering in Silicon-on-Insulator MOSFETs Through Source/Drain Engineering for Low-Operating-Power System-on-Chip Applications

Abstract: In this paper, the authors propose novel metal-oxide-semiconductor field-effect transistor (MOSFET) types featuring additional L-shaped counterdoped areas in the source and/or drain regions of silicon-on-insulator (SOI) MOSFETs to reduce drain-induced barrier lowering (DIBL) through the buried oxide (BOX) layer. The L-shaped region in the drain area shields the BOX layer from penetration by the drain electric field, thereby reducing DIBL in the body region. Simulation of the electrical characteristics of these novel MOSFETs demonstrated more remarkable DIBL suppression and subthreshold slope performance in short-channel regions than in conventional SOI MOSFETs. In addition to this suppression, these novel MOSFETs suppress breakdown voltage more effectively than conventional SOI MOSFETs. The authors concluded that the proposed devices are capable of contributing to the scaling of SOI MOSFETs in ultralarge-scale integration circuits.

Creation of metal-containing carbon onions via self-assembly in metallocene/benzene solution irradiated with an ultraviolet laser

Abstract: We irradiate sub- and super-critical benzene, in which metallocene such as ferrocene or cobaltocene is dissolved, with a UV laser of 266nm wavelength, and show that benzene and metallocenes are dissociated and iron- and cobalt-containing carbon onions (Fe@C and Co@C) are created. The operational temperature of the present method is much lower than that of conventional ones for the growth of nanomaterials and therefore coagulation among metal-containing carbon onions is avoided. The average diameters of the core iron and cobalt nanoparticles are, respectively, 7.5 and 7.2nm, whereas the thickness of the layers of carbon onions surrounding the core metal particles is 3.2nm in both Fe@C and Co@C cases. The metal-containing carbon onions show superparamagnetic characteristics.

Deposition of C60, C70 and C84 fullerene molecules, in benzene via a change of the fluid state, from a gas–liquid two phase region to the critical point

Abstract: We dissolve C60, C70 or C84 molecules in benzene and change the fluid state from a gas–liquid two-phase region (250 °C) to the critical point (2890 °C) and from the critical point to the original state (250 °C) along the gas–liquid coexistence curve We find that particle-like and whisker-like nano/micro clusters, which are composed of C60 molecules, deposit on the surface of a silicon substrate placed vertically in C60/benzene solution during the temperature change, whereas no appreciable clusters are detected on the silicon substrate in either C70/benzene or C84/benzene solutions The clusters, in which fcc lattice structures are formed by C60 molecules, remain stable in the solution The present result suggests that C60 molecules can be separated and extracted from a mixture of C60, C70 and C84 molecules dissolved in benzene

Lower-Energy Structure Optimization of (C-60)(N) Clusters Using an Improved Genetic Algorithm

Abstract: NSFC [51271156]; National Defense Basic Scientific Research program of China [B1420110155]; Natural Science Foundation of Fujian Province of China [2012J05125, 2011J01373]; Foundation of Key Laboratory of System Control and Information Processing, Ministry of Education, P.R. China [SCIP2011004]