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Kasukabe, Yoshitaka*; Watanabe, Yohei*; Yamamoto, Shunya; Yoshikawa, Masahito; Fujino, Yutaka*
e-Journal of Surface Science and Nanotechnology (Internet), 7, p.625 - 632, 2009/04
Titanium nitrides (TiN) are non-stoichiometric compounds and show covalent properties as well as metallic and ionic properties, which make them fascinating for both fundamental research and technological applications. The purpose of this work is to study changes of the crystallographic and electronic structures of Ti films by heating and by nitriding during N-implantation into Ti films separated from NaCl(001) substrates, using in-situ transmission electron microscope (TEM) equipped with the instrument for electron energy loss spectroscopy (EELS), and then to clarify the atomistic nitriding processes of Ti thin films due to the N-implantation with the aid of molecular orbital calculations. The present calculations throw light on the hcp-fcc transformation mechanism between fcc-Ti sublattices and hcp sublattices due to the release of H atoms or due to the implantation of N atoms, taking into account the bonding interaction of Ti sublattices with ligand H or N atoms.
Hashimoto, Mie; Fukaya, Yuki; Kawasuso, Atsuo; Ichimiya, Ayahiko
no journal, ,
no abstracts in English
Narita, Ayumi; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Honda, Mitsunori; Hirao, Norie; Yaita, Tsuyoshi
no journal, ,
Photon or electron irradiation breaks chemical bond and induces desorption of fragment. However, formation of chemical bond from adsorbed light molecules, such as methane, by high energy radiation has scarcely been reported. This process is important in space, because organic molecules can be formed through these reactions. In this report, we have investigated formation of molecular ions and neutral molecules with covalent bond from frozen methane by He+ ion irradiation. It was found that acetylene ion(C2H2+), and ethylene ion(C2H4+) with covalent bond were formed by He+ ion irradiation. These results were compared with Monte-Carlo simulation for energy-loss processes of He+ ions in solid methane. As a result, it was elucidated that molecular ions are formed inside of frozen methane by high-density excitation due to nuclear collision. On the other hand, neutral molecules are formed by rapid evaporation due to temperature increase along the nuclear track.
by 10 keV O
and N irradiationKitazawa, Sin-iti; Saito, Yuichi; Motohashi, Kenji*
no journal, ,
Photon emission produced by radiation irradiation is called radiation-induced luminescence (RIL), which has characteristic wavelengths for band structures, lattice defects and impurity levels. For RIL of TiO by 10 keV O irradiations, some UV and visible bands were observed at room temperature. The range of 10 keV O into TiO is about 30 nm, and the surface effect must be considered in this study. In this work, RIL spectra of Au or Pt coated TiO by 10 keV O and N irradiations were observed. The TiO film is prepared by anatase powder, which consists of nano-photochemistry diodes. Many atomic lines, visible bands at 2.0 and 2.6 eV and a UV band at 3.9 eV, were observed. This study clarifies part of the RIL mechanism of TiO, which is to be expected for a photocatalytic material.
Teraoka, Yuden; Yoshigoe, Akitaka; Harries, J.
no journal, ,
In order to study correlation between hydrogen desorption and chemical bonding states of native over-layer, synchrotron radiation photoemission spectroscopy has been applied for analyses of the oxide, its thermal instability and the artificial oxides formation on V(001) and V(111). O1s photoemission spectra for the over-layer consisted of at least two components. The lower binding energy component was bulk sensitive. V2p photoemission peaks contributed from bulk could be observed with photon energy larger than 795eV for V(111) and 688eV for V(001) so that the over-layer thickness might be at least 2nm and 1.5nm, respectively. The O1s peak decreased to be negligible by heating up to 900K. The clean surface was irradiated by supersonic oxygen molecular beams with translational energy of 2.3eV at room temperature. Although a similar oxide layer was formed, the thickness was smaller than that of native oxide.
Matsumoto, Yoshihiro; Sakai, Seiji; Naramoto, Hiroshi*; Nakagawa, Takeshi*; Takagi, Yasumasa*; Yokoyama, Toshihiko*; Hirao, Norie; Baba, Yuji; Shimada, Toshihiro*; Maeda, Yoshihito
no journal, ,
Recently, we have found that the codeposited C60-Co films where Co nanoparticles are dispersed into the matrix of the C60-Co compound show large tunnel magnetoresistanene (TMR) effects at low temperatures. The observed MR ratios cannot be explained by a spin-polarization of crystalline Co, so it is expected that the C60-Co compound mediates an enhancing effects to the spin-dependent transport in the films. In the present work, we have investigated the spin states of the C60-Co films by X-ray magnetic circular dichroism spectroscopy. As the results, MCD spectra of the C60-Co compound show the sensitivity to the sample temperature, which is consistent to the temperature dependence of MR ratios. This indicates clearly that spin-polarized states of the C60-Co compound influences the degree of spin-dependent transport in the films.
adsorption on Si(111)-7
7 by translational kinetic energy of O revealed by real-time XPS using synchrotron radiationYoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
no abstracts in English
