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Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nath, K. G.*
Physica Status Solidi (C), 9(6), p.1450 - 1453, 2012/06
Times Cited Count：3 Percentile：72.43(Physics, Applied)no abstracts in English
Kataoka, Takashi*; Kobayashi, Masaki*; Sakamoto, Yuta*; Song, G. S.*; Fujimori, Atsushi*; Chang, F.-H.*; Lin, H.-J.*; Huang, D. J.*; Chen, C. T.*; Okochi, Takuo*; et al.
Journal of Applied Physics, 107(3), p.033718_1 - 033718_7, 2010/02
Times Cited Count：57 Percentile：86.35(Physics, Applied)Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Hirao, Norie*; Nath, K. G.*
Physical Review B, 74(20), p.205433_1 - 205433_5, 2006/11
Times Cited Count：4 Percentile：21.95(Materials Science, Multidisciplinary)no abstracts in English
Uddin, M. N.*; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Nath, K. G.*; Baba, Yuji; Nagano, Masamitsu*
JAEA-Research 2006-034, 72 Pages, 2006/06
JAEA-Research-2006-034.pdf:4.05MB
no abstracts in English
Uddin, M. N.*; Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nath, K. G.*; Nagano, Masamitsu*
Journal of Applied Physics, 99(8), p.084902_1 - 084902_5, 2006/04
Times Cited Count：5 Percentile：16.70(Physics, Applied)no abstracts in English
-irradiated graphite surfaces using photon-stimulated desorption spectroscopySekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.
Surface and Interface Analysis, 38(4), p.352 - 356, 2006/04
Times Cited Count：3 Percentile：6.96(Chemistry, Physical)We investigated the orientation nature at the top-most layers of F-irradiated graphite using polarization dependent near-edge X-ray absorption fine structure (NEXAFS) spectroscopy which incorporates partial electron yield (PEY) detection and photon-stimulated ion desorption (PSID) techniques. The fluorine K-edge NEXAFS spectra conducted in PEY mode show no significant dependence on polarization angles. In contrast, NEXAFS spectra recorded in F ion yield mode show enhanced yields at a feature of 
689.4 eV assigned as a 
*(C-F) state relevant to =C-F sites, which depend on polarization angles. The C-F bonds prefer relatively tilting down the surface at the top-most layer, while the C-F bonds are randomly directed at deeper regions. We conclude that the difference in the orientation structures between the top surface and bulk is reflected in the NEXAFS recorded in the two different detection modes. It was also found that H- and F
- PSID NEXAFS spectra are helpful in understanding desorption mechanism, thus in analysing NEXAFS data.
)SiX (X = F, Cl, Br, I, NCO) as studied using NEXAFS spectroscopySekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.*; Uddin, M. N.*
Journal of Physics; Condensed Matter, 17(36), p.5453 - 5466, 2005/09
Times Cited Count：1 Percentile：5.90(Physics, Condensed Matter)The orientation nature of multilayer organosilicon compounds has been investigated by measuring the dependence of the Si K-shell near-edge X-ray absorption fine structures (NEXAFS) on the polarization angle. Two approaches helped to elucidate the orientation mechanism: the substitution effect and the deposition-rate dependence. The orientation angles of Si-X bond axes were obtained for trimethylsilyl halides, (CH)SiX (X =F Cl Br I NCO, condensed on Cu(111) at a low (82 K) temperature: the angles are 60, 73, 61, 55, and 55 degrees with respect to the surface normal, for X =F, Cl, Br, I, and NCO, respectively. Chloride (X =Cl) produces the most parallel tilt angle. The specific orientation nature of chloride is attributed to its strong dipole moment as well as the regular tetrahedron shape of the molecule. The molecular volumes calculated verify this view. Furthermore, deposition rates are found to greatly influence the growth manner: namely, high deposition rates led to a slightly perpendicular orientation of Si-X bond axis.
Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.
Journal of Electron Spectroscopy and Related Phenomena, 144-147, p.437 - 441, 2005/06
Times Cited Count：3 Percentile：17.30(Spectroscopy)no abstracts in English
Nath, K. G.; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Baba, Yuji
Journal of Electron Spectroscopy and Related Phenomena, 144-147, p.323 - 326, 2005/06
Times Cited Count：5 Percentile：26.99(Spectroscopy)The effect of laser annealing on electronic atructures and molecular orientation for poly(dimethylsilane), {PDMS, [Si(CH)
]
} has been studied by synchrotron radiation photoemission and photoabsorption spectroscopy. Prior to annealing, PDMS powder was mounted on the basal plane of highly oriented pyrolytic graphite. Both Si 1s X-ray photoemission spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at Si 1s edge show that electronic structures have been modified due to annealing. Furthermore, the angle-dependent NEXAFS spectra clearly indicate that the annealed products maintain a specific orientation. Interestingly, no such kind of orientation is present in as-received PDMS powder as no angle-dependency is observed before annealing.
Uddin, M. N.; Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nath, K. G.; Nagano, Masamitsu*
Applied Surface Science, 241(1-2), p.246 - 249, 2005/01
Times Cited Count：8 Percentile：36.20(Chemistry, Physical)Recently, much attention has been given on the synthesis and characterization of graphite-like B-C-N hybrid. Since graphite-like B-C-N hybrid may have semiconducting property, this material is interesting for applications to electronic and luminescent devices. In order to synthesize this material, borazine ion plasma was implanted in graphite at room temperature (RT) and 600 
C. An ultrahigh vacuum (UHV) chamber with base pressure 10
Pa was used for the experiment. The X-ray photoelectron spectroscopy (XPS) study suggested that B atoms in the deposited films are in a wide variety of atomic environment such as BC3, BN3 and B-C-N hybrid. The ratios of these coordinations strongly depend on the temperature during the ion implantation. It was found that the B-C-N hybrid is predominantly synthesized by the implantation at 600 C where the surface [B]/([B]+[C]+[N]) ratio ranges from 0.1 to 0.35. The results imply that it is possible to control the composition of B-C-N hybrid by changing the fluence of the ion plasma and the temperature of graphite during ion implantation.
Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Nath, K. G.
Applied Surface Science, 237(1-4), p.176 - 180, 2004/10
Times Cited Count：9 Percentile：43.26(Chemistry, Physical)no abstracts in English
-BN thin film on Ni(111) using NEXAFS spectroscopyShimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nath, K. G.
Hyomen Kagaku, 25(9), p.555 - 561, 2004/09
no abstracts in English
Nath, K. G.; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Baba, Yuji
Applied Surface Science, 234(1-4), p.234 - 239, 2004/07
Times Cited Count：7 Percentile：36.89(Chemistry, Physical)Here we report oxidization properties of Si nanostructures grown on graphite. Si 1s X-ray photoemission spectra using synchrotron radiation are used in order to understand the oxidization pathways. Several Si films, such as 0.4, 2, 5.5 & Aring; were grown on highly oriented pyrolitic graphite (HOPG). In the case of a 0.4 & Aring; Si on HOPG, where different types of Si nanostructures in the form of nanoclusters are present, oxygen reactivity is nearly zero. In contrast, the thick film (5.5 & Aring;), where a bulk-type phase is present, shows a higher degree of reactivity. The results are discussed on the basis of nanostructure geometry, number of constituting Si atoms and cluster size.
Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Nath, K. G.
Applied Surface Science, 234(1-4), p.246 - 250, 2004/07
Times Cited Count：10 Percentile：46.03(Chemistry, Physical)no abstracts in English
Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nath, K. G.
Journal of Electron Spectroscopy and Related Phenomena, 137-140, p.573 - 578, 2004/07
Times Cited Count：30 Percentile：74.03(Spectroscopy)Hexagonal boron nitride (h-BN) thin film has been epitaxially formed on Ni(111) by chemical vapor deposition using borazine gas. The electronic structure of this system is studied by near edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS). The thickness of the h-BN is estimated to be about two-layers from XPS. B K-edge NEXAFS spectra show new 
* peak which is not observed in the spectrum for bulk h-BN. From a polarization dependence analysis of NEXAFS, we propose this new * peak originates from the interaction between the h-BN and Ni(111). This new * peak clearly proves that conduction band of h-BN/Ni(111) is different from that of bulk h-BN.
Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.
Free Electron lasers 2003, p.II_69 - II_70, 2004/00
no abstracts in English
Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nath, K. G.; Sasaki, Masayoshi*; Okuno, Kenji*
Journal of Vacuum Science and Technology A, 21(6), p.1843 - 1848, 2003/11
Times Cited Count：6 Percentile：27.84(Materials Science, Coatings & Films)Ion implantation method is applied to synthesize B-C-N hybrids and their electronic structures are characterized by X-ray photoelectron spectroscopy. A boron nitride film is deposited on a graphite target by borazine plasma implantation. At the interface between the BN film and the graphite, variety of bonding combinations including B-N, B-C, and C-N are observed. This proved that B-C-N hybrids is formed by this method.
Sekiguchi, Tetsuhiro; Ikeura-Sekiguchi, Hiromi*; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.
Photon Factory Activity Report 2002, Part B, P. 80, 2003/11
no abstracts in English
Nath, K. G.; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Baba, Yuji
Journal of Applied Physics, 94(7), p.4583 - 4588, 2003/10
Times Cited Count：16 Percentile：53.41(Physics, Applied)no abstracts in English
Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Nath, K. G.*; Hirao, Norie*
no journal, ,
no abstracts in English
