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156. Preface

Author

Komori, Fumio, primary, Yoshinobu, Jun, additional, Takahashi, Toshio, additional, and Kasai, Hideaki, additional

Published
2007
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169. Direct Observation of Molecule-Substrate Antibonding States near the Fermi Level in Pd(110)-c(4x2)-Benzene

Author

Yoshinobu, Jun, Kawai, Maki, Imamura, Issei, Marumo, Fumiyuki, Suzuki, Ryochi, Ozaki, Hiroyuki, Aoki, Masaru, Masuda, Shigeru, Aida, Misako, Yoshinobu, Jun, Kawai, Maki, Imamura, Issei, Marumo, Fumiyuki, Suzuki, Ryochi, Ozaki, Hiroyuki, Aoki, Masaru, Masuda, Shigeru, and Aida, Misako

Abstract

type:text, Evidence for a molecule-substrate hybridized state near the Fermi level EF is presented for Pd(110)- c(4x2)-benzene. Observed images of adsorbed benzene near EF by scanning tunneling microscopy consist of two elongated protrusions separated by a single nodal depression with C2 symmetry. The existence of a benzene derived state near EF is also observed by metastable atom electron spectroscopy, and it is assigned to the antibonding states between the 1e1g molecular orbital of benzene and the Pd 4d orbitals by ab initio molecular orbital calculations.

Published
1997

194. Observation of charge transfer states of F4-TCNQ on the 2-methylpropene chemisorbed Si(100)(2×1) surface

Author

Mukai, Kozo and Yoshinobu, Jun

Subjects
*CHARGE transfer, *PROPENE, *CHEMISORPTION, *SILICON, *METHANE, *MOLECULAR orbitals, *PHOTOELECTRON spectroscopy, *SURFACE chemistry
Abstract

Abstract: We have investigated the valence electronic states of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) on the 2-methylpropene chemisorbed Si(100)(2×1) surface using valence photoelectron spectroscopy. Since the electron affinity of condensed F4-TCNQ is 5.24eV and the energy from the valence band maximum of the 2-methylpropene saturated Si(100)(2×1) surface to the vacuum level is 4.1eV, spontaneous charge transfer would be expected in the present system. At sub-monolayer coverage of F4-TCNQ, characteristic peaks are observed at 1.1 and 2.5eV below Fermi energy. The former peak is assigned to a singly occupied affinity level, and the latter is ascribed to a relaxed highest occupied molecular orbital of adsorbed F4-TCNQ. The work function change is increased up to +1.3eV as a function of F4-TCNQ coverage. These results support the occurrence of charge transfer into F4-TCNQ on the 2-methylpropene saturated Si(100)(2×1) surface. [Copyright &y& Elsevier]

Published
2009
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197. Aqueous-Phase Oxidation of Epitaxial Graphene on the Silicon Face of SiC(0001)

Author

Hossain, Md. Zakir, Razak, Maisarah B. A., Yoshimoto, Shinya, Mukai, Kozo, Koitaya, Takanori, Yoshinobu, Jun, Sone, Hayato, Hosaka, Sumio, and Hersam, Mark C.

Abstract

To explore the chemical and electronic states of oxidized epitaxial graphene (EG) grown on the Si face of SiC(0001), we employ the Hummers oxidizing agents (H2SO4+ NaNO3+ KMnO4) under different reaction conditions that oxidize the graphene layer. The resulting material is characterized with scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). A mild “drop-cast” procedure at 60 °C is found to be equally effective at oxidizing EG as the conventional Hummers procedure. This aqueous-phase oxidation reaction appears to proceed in an autocatalytic manner as indicated by the concurrent observation of patches of oxidized and clean graphene areas in atomically resolved STM images on partially oxidized EG. STS further reveals substantial changes in electronic structure for oxidized EG including the opening of a local band gap of ∼0.4 eV. The oxidation is confined to the graphene layers as verified by XPS characterization of the underlying SiC substrate. In contrast to EG oxidized in ultrahigh vacuum that contains only epoxy groups and can be fully reverted back to pristine EG following annealing at 260 °C, aqueous-phase oxidized EG possesses carbonyl and hydroxyl groups in addition to the dominant epoxy groups and thus remains partially oxidized even following annealing at 1000 °C.

Published
2014
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198. Elucidation of Rh-Induced In-Gap States of Rh:SrTiO3Visible-Light-Driven Photocatalyst by Soft X-ray Spectroscopy and First-Principles Calculations

Author

Kawasaki, Seiji, Akagi, Kazuto, Nakatsuji, Kan, Yamamoto, Susumu, Matsuda, Iwao, Harada, Yoshihisa, Yoshinobu, Jun, Komori, Fumio, Takahashi, Ryota, Lippmaa, Mikk, Sakai, Chikako, Niwa, Hideharu, Oshima, Masaharu, Iwashina, Katsuya, and Kudo, Akihiko

Abstract

The occupied and unoccupied in-gap electronic states of a Rh-doped SrTiO3photocatalyst were investigated by X-ray emission spectroscopy and X-ray absorption spectroscopy for different Rh impurity valence states and doping levels. An unoccupied midgap Rh4+acceptor state was found 1.5 eV below the SrTiO3conduction band minimum. Both Rh4+and Rh3+dopants were found to have an occupied donor level close to the valence band maximum of SrTiO3. The density of states obtained from first-principles calculations show that all observed spectral features can be assigned to electronic states of substitutional Rh at the Ti site and that Rh:SrTiO3is an unusual titanate compound with a characteristic p-type electronic structure. The Rh doping results in a large decrease of the bandgap energy, making Rh:SrTiO3an attractive material for use as a visible-light-driven H2-evolving photocatalyst in a solar water splitting reaction.

Published
2012
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199. Different Adsorbed States of 1,4-Cyclohexadiene on Si(001) Controlled by Substrate Temperature

Author

S. Kato, Hiroyuki, Wakatsuchi, Masayuki, Kawai, Maki, and Yoshinobu, Jun

Abstract

To elucidate the thermal chemical processes of 1,4-cyclohexadiene (C6H8) on Si(001), the adsorption states were characterized by temperature-programmed desorption (TPD), low-energy electron diffraction (LEED), and high-resolution electron energy-loss spectroscopy (HREELS), in comparison with those for benzene (C6H6) and cyclohexene (C6H10). Consequently, three types of adsorption states, i.e., -complex, single di- bonding, and double di- bonding species, were identified. At 85 K, all 1,4-cyclohexadiene molecules are adsorbed as -complex species in the first layer. With increasing substrate temperature, above 150 K, these -complex species chemically convert to single di- bonding species by 2 2 cycloaddition with a Si dimer. Upon further heating above 300 K, most single di- bonding species are dehydrogenated into benzene and then the benzene molecules desorb from the surface. In contrast, double di- bonding species are formed preferentially in low exposure at 300 K, and are dehydrogenated into benzene above 600 K.

Published
2007
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200. Effect of Transplanted Pieces from Non-X-irradiated Worms on Irradiated Ones in Dugesia japonica

Author

SUGINO, Hisao, OKUNO, Yoshinobu, and YOSHINOBU, Jun

Abstract

1. Upon X-ray irradiation at a dose over 3,000r regeneration of tissue of freshwater planarian, Dugesia japonica Ichikawa et Kawakatsu was completely inhibited, and the worm decayed resulting in death. But even just before death some neoblasts remained. 2. When the anterior part of an irradiated worm was joined to the posterior part of a non-irradiated worm, a cut was made in the anterior part, a head regenerated at the anterior cut surface to form a normal worm. Neoblats from the non-irradiated component multiplied by division and invaded the irradiated component, replacing the irradiated tissue. 3. When an irradiated worm and a non-irradiated worm were sectioned longitudinally along the median line, and corresponding parts were exchanged, and subsequently the head removed, healthy tissue invaded the irradiated component, resulting in a normal worm. 4. The irradiated region between the regeneration bud and non-irradiated region contains neoblasts and "differentiating cells" derived from them, just like the regeneration bud. From this and other data we propose that neoblasts do not migrate directly by ameboid movement, but reach the cut surface after repeated fission and multiplication. 5. The possibility that irradiated neoblasts recover under the influence of healthy tissue is excluded. Acknowledgement The authors wish to express sincere thanks to Dr. Atsuhiko Takeda, Radiation Center of Osaka Prefecture, and Dr. Iwashiro Oki, Osaka Prefetural Institute of Public Health, for their kind guidance on the techniques of X-ray irradiation.

Published
1971

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