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beamOgawa, Shuichi*; Takakuwa, Yuji*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Teraoka, Yuden; Moritani, Kosuke*; Mizuno, Yoshiyuki*
Denki Gakkai Rombunshi, C, 127(2), p.140 - 145, 2007/02
The initial sticking probability of O molecule on a Ti(0001)-1
1 surface at room temperature was measured as a function of translational kinetic energy by real-time photoelectron spectroscopy. The O 1s photoelectron spectra can be fitted well with three components A, B, and C, where the chemical shift of component B and C are +0.7 and +1.6 eV relative to the binding energy of component A (528.8 eV). Upon exposing to the O beam, component A and C appear dominantly and component B grows with an incubation time, indicating that two kinds of chemical adsorption states are concerned with dissociative adsorption of O molecule at the initial stage. The incident energy dependence of initial sticking probability shows quite different behaviours between component A and C: initial sticking probability of component C decreases monotonously with incident energy and is almost constant above 0.6 eV, while initial sticking probability of component A shows a rapid decrease followed by a gradual increase with a minimum at 0.5 eV and then decreases with two small maxima at 0.9 and 1.8 eV. The observed incident energy dependence of initial sticking probability for component A and C are discussed in terms of a trapping-mediated dissociative adsorption and a direct dissociative adsorption process.
molecular beamsOgawa, Shuichi*; Takakuwa, Yuji*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Teraoka, Yuden; Mizuno, Yoshiyuki*
Shinku, 49(12), p.775 - 779, 2006/12
Nitridation on a Ti(0001)-11 surface using a supersonic N molecular beam was investigated by real-time photoelectron spectroscopy to clarify the adsorption reaction dynamics of N molecule on the Ti surface. In a whole N dosage region examined, N 1s spectra can be fitted well with two chemically-shifted components, the binding energies of which are 396.9 and 396.6 eV, respectively. For both the components, the initial sticking probability S
shows a decrease with increasing incident energy in the overall trend, while has significant minima at 0.3 and 1.5 eV. Such incident energy dependences of S suggest that the chemisorbed states are similarly caused by a trapping-mediated adsorption process through a physisorption state at lower incident energy than 0.3 eV and an activated adsorption process becomes dominant at higher incident energy than 0.3 eV.
Ogawa, Shuichi*; Takakuwa, Yuji*; Ishizuka, Shinji*; Mizuno, Yoshiyuki*; Tonda, Hideki*; Homma, Teiichi*; Teraoka, Yuden; Yoshigoe, Akitaka; Moritani, Kosuke; Hachiue, Shunsuke
JAERI-Tech 2004-046, 25 Pages, 2004/06
JAERI-Tech-2004-046.pdf:2.51MB
We investigated the correlation between initial sticking coefficient and O transitional kinetic energy to understand O adsorption processes on the Ti(0001) surface via photoemission spectroscopy for O-1s and Ti-2p core levels using the surface reaction analysis apparatus, installed at the JAERI soft X-ray beamline BL23SU in the SPring-8. We observed the decrease of initial sticking coefficient of O molecules on the Ti(0001) surface with increasing O transitional kinetic energy. We concluded that the O adsorption on the Ti(0001) surface proceeded by a trapping-mediated dissociative adsorption mechanism. The constant dependence of the initial sticking coefficient on incident angle of O beams also suggested the propriety of the trapping-mediated surface reaction mechanism.
Takakuwa, Yuji*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Teraoka, Yuden; Moritani, Kosuke; Ogawa, Shuichi*; Mizuno, Yoshiyuki*; Tonda, Hideki*; Homma, Teiichi*
Shinku, 47(6), p.457 - 461, 2004/06
The oxidation reaction of Ti(0001) surface by oxygen molecules was observed by real-time in-situ photoemission spectroscopy using synchrotron radiation in the conditions of 400
C and 3.710
Pa. The uptake curve of oxygen showed a plateau at the dose of 45-85 L and then increased again. This re-growth of oxide film was attributed to the drastic change of Ti oxidation state from TiO to TiO. Consequently, the characteristic change of the uptake curve was caused by the oxidation state change of Ti atoms.
Takakuwa, Yuji*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Teraoka, Yuden; Mizuno, Yoshiyuki*; Tonda, Hideki*; Homma, Teiichi*
Hyomen Kagaku, 24(8), p.500 - 508, 2003/08
Temperature dependence of the initial oxidation kinetics of Ti(0001) surface was investigated by low energy electron diffraction (LEED) and real-time photoelectron spectroscopy. The LEED observation revealed that the oxide layers grew epitaxially. From the oxygen uptake curve, it was clarified that oxigen diffusion was significantly enhanced by surface temperature and the oxide layers thickness reached to 7 nm at 400C. From Ti-2p photoelectron spectroscopy, TiO was predominant at the subsurface while TiO and TiO
components were also observed at the interface.
Takakuwa, Yuji*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Teraoka, Yuden; Yamauchi, Yasuhiro*; Mizuno, Yoshiyuki*; Tonda, Hideki*; Homma, Teiichi*
Applied Surface Science, 216(1-4), p.395 - 401, 2003/06
Times Cited Count：19 Percentile：65.52(Chemistry, Physical)Real-time in-situ observation using photoelectron spectroscopy for elementary processes of Ti(0001) oxidation by O molecules has been performed at the surface reaction analysis apparatus installed at the BL23SU in the SPring-8. And the real-time observation has been also performed by RHEED-AES methods at Tohoku University. The partial pressure region of oxygen was from 2x10
Torr to 8x10
Torr. The surface temperature was 473 K and 673 K. The variation from clean Ti surface toward TiO was comfirmed by observation of Ti-2p and O-1s photoelectron spectra. Reflected electron intensity and O-KLL Auger electron intensity oscillated in the RHEED-AES measurements. These facts revealed that the surface morphological change of the oxidized Ti(0001) surface was associated not only with a disappearance of the surface metallic layer but also with a change of the oxidation state.
Takakuwa, Yuji*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Teraoka, Yuden; Mizuno, Yoshiyuki*; Tonda, Hideki*; Homma, Teiichi*
Nuclear Instruments and Methods in Physics Research B, 200, p.376 - 381, 2003/01
Times Cited Count：10 Percentile：56.35(Instruments & Instrumentation)no abstracts in English
Ogawa, Shuichi*; Takakuwa, Yuji*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Teraoka, Yuden; Mizuno, Yoshiyuki*
no journal, ,
Nitridation reactions of a Ti(0001) surface, induced by supersonic nitrogen molecular beams, were analysed via real-time in-situ photoemission spectroscopy with synchrotron radiation. Surface temperature dependence of nitrogen uptake curves and nitrided chemical bonding states were investigated. The incident energy range of supersonic nitrogen molecular beams was from 0.03 eV to 1.99 eV. Surface temperature was set at 27C, 200C, and 400C. The photon energy of synchrotron radiation was 668 eV. A photoemission spectrum of N1s peak could be recorded successfully with a period of 26s. Although the N1s photoemission peak was composed of 2 components at 27C and 200C, an additional conponent was needed at 400C.
Ogawa, Shuichi*; Takakuwa, Yuji*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Teraoka, Yuden; Mizuno, Yoshiyuki*
no journal, ,
In order to study adsorption reaction dynamics of nitrogen molecules at Ti surfaces, Ti(0001) nitridation processes via supersonic nitrogen molecular beams were observed by real-time photoelectron spectroscopy. Incident energy dependence of initial sticking probability was investigated for each adsorption state of nitrogen molecules. The N1s photoemission peak consists of two components. The incident energy dependence of initial sticking probability was obtained from adsorption uptake curves for each component. The two components revealed almost same tendency. It was indicated that dissociative adsorption via a physical adsorption state was a major process in the incident energy less than 0.3 eV, and direct adsorption took place mainly in the incident energy larger than 0.3 eV.
Takakuwa, Yuji*; Ogawa, Shuichi*; Ohira, Masayuki*; Ishizuka, Shinji*; Yoshigoe, Akitaka; Teraoka, Yuden; Mizuno, Yoshiyuki*; Yamauchi, Yasuhiro*; Homma, Teiichi*
no journal, ,
Oxidation processes of Ti(0001)-11 clean surface were analyzed by real-time monitoring using a variety of surface analysis methods of XPS, UPS, and AES/RHEED. Following conclusions were obtained by these observations. Oxide layer grows epitaxially at the Ti(0001) surface with a 
structure. Surface roughness changes periodically. The period is consistent with that of work function. Low oxidation state (TiO) plays a dominant role in the dissociative adsorption of oxygen molecules. The oxide layer decomposes easily at surface temperature over 673 K. The TiO structure reduces to TiO during thermal decomposition.
