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Ogiwara, Norio; Hikichi, Yusuke; Kuroiwa, Masahide*
Vacuum, 86(7), p.908 - 912, 2012/02
Times Cited Count:1 Percentile:4.24(Materials Science, Multidisciplinary)Narita, Ayumi; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Hirao, Norie; Yaita, Tsuyoshi
Applied Surface Science, 258(6), p.2034 - 2037, 2012/01
Times Cited Count:4 Percentile:18.72(Chemistry, Physical)In order to apply the organic thin films to electric and optical devices, the immobilization of organic molecules on inorganic substrate is essential. Considering optical devices, it is important to immobilize organic molecules on oxide surfaces, because many of oxides have insulating and transparent properties. In this study, we have investigated the chemical states of the interface between organic molecules with silicon alkoxide and sapphire surfaces by X-ray photoelectron spectroscopy and near edge absorption fine structure (NEXAFS). Octadecyl-triethoxy-silane (ODTS) molecules which are terminated by silicon alkoxide were adsorbed on sapphire surfaces. On the basis of the Si 1s XPS spectra for monolayer, it is supposed that the chemical bond between silicon alkoxide and the surface is formed. For Si K-edge NEXAFS spectra, the polarization dependence was observed, which suggests that the Si-O bond in ODTS was located perpendicular to the surface.
Mannan, M. A.*; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Hirao, Norie; Narita, Ayumi; Nagano, Masamitsu*; Noguchi, Hideyuki*
no journal, ,
The electric and optical properties in thin films of one-dimensional polymers strongly depend on the molecular orientation, so the molecular orientations of polydimethylsilane (PDMS) on various metal and semiconductor surfaces have been investigated. The substrates investigated were copper, highly oriented pyrolytic graphite (HOPG), and indium tin oxide (ITO). The orientations were studied by Si K-edge near-edge X-ray absorption fine structure (NEXAFS). Polarization dependences of the NEXAFS spectra showed that the PDMS molecules are self-ordered and the backbones of the polymers are perpendicularly oriented on copper and ITO surfaces. While, it was found that the molecular orientation of PDMSs on HOPG surface is reverse to those on copper and ITO surfaces, i.e., nearly parallel to the HOPG surface. It was concluded that the flatness of the surface determines the orientation of the first layer, and the orientation of the succeeding layers follow the first layer.
Yamamoto, Hiroyuki; Esaka, Fumitaka; Matsue, Hideaki; Sasase, Masato*
no journal, ,
Non-destructive depth profiling of buried interface has been performed by measuring energy of emitted ions with neutron irradiation.
Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro
no journal, ,
Heteroatom doping has been expected to control properties of carbon materials like catalysis. However, the correlation between structures and properties has not been well clarified because of the complicated structures around dopants. We studied local structure of B- and N-doped graphite by NEXAFS spectroscopy and found different configurations around dopant sites. However, the electronic structures observed in NEXAFS have not been well interpreted theoretically. In this work, we performed DV-X density functional theory calculations for some model clusters that have graphite-like planar and fullerene-like curved structures, and propose that curved structure has characteristic electronic structure at dopant sites. We also discuss O
adsorption property difference between planar and curved structures using molecular orbital calculations.
Ogiwara, Norio; Kanazawa, Kenichiro; Yanagibashi, Toru
no journal, ,
Esaka, Fumitaka; Yamamoto, Hiroyuki; Udono, Haruhiko*; Matsubayashi, Nobuyuki*; Yamaguchi, Kenji; Shamoto, Shinichi; Magara, Masaaki; Kimura, Takaumi
no journal, ,
Surface depth profiling of FeSi single crystals has been performed by synchrotron radiation excited XPS and XAS.