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Journal Articles

Characterization of F$$^{+}$$-irradiated graphite surfaces using photon-stimulated desorption spectroscopy

Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.

Surface and Interface Analysis, 38(4), p.352 - 356, 2006/04

 Times Cited Count:3 Percentile:7.57(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 $$sim$$689.4 eV assigned as a $$sigma$$*(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$$^{2+}$$- PSID NEXAFS spectra are helpful in understanding desorption mechanism, thus in analysing NEXAFS data.

Journal Articles

Mechanism of state-specific enhancement in photon-stimulated desorption as studied using a polarization-dependent technique

Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Wu, G.*; Kitajima, Yoshinori*

Surface Science, 593(1-3), p.310 - 317, 2005/11

 Times Cited Count:2 Percentile:12.09(Chemistry, Physical)

Using a newly developed rotatable time-of-flight mass spectrometer(R-TOF-MS) and polarized synchrotron radiation, orientation effect on fragmentation and desorption pathways occurring at the top-most layers of molecular solids have been investigated. Reported will be polarization-angle dependencies of TOF mass spectra, high-resolution electron- and ion-NEXAFS in condensed chlorobenzene.

Journal Articles

Direct and indirect processes in photon-stimulated ion desorption from condensed formamide

Ikeura, Hiromi*; Sekiguchi, Tetsuhiro; Baba, Yuji; Imamura, Motoyasu*; Matsubayashi, Nobuyuki*; Shimada, Hiromichi*

Surface Science, 593(1-3), p.303 - 309, 2005/11

 Times Cited Count:5 Percentile:26.91(Chemistry, Physical)

no abstracts in English

Journal Articles

Local bonding states of ion-irradiated graphite characterized by photon-stimulated desorption (PSD) spectroscopy

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:18.19(Spectroscopy)

no abstracts in English

Journal Articles

Characterization and degradation of ZEP520 resist film by TOF-PSID and NEXAFS

Ikeura, Hiromi*; Sekiguchi, Tetsuhiro; Koike, Masaki*

Journal of Electron Spectroscopy and Related Phenomena, 144-147, p.453 - 455, 2005/06

 Times Cited Count:15 Percentile:58.45(Spectroscopy)

no abstracts in English

Journal Articles

Polarization-dependent dissociation selectively induced by core-electron excitation in methyl ester terminated self-assembled monolayer

Kizaki, Hiroyuki*; Wada, Shinichi*; Sako, Erika*; Sumii, Ryohei*; Waki, Satoshi*; Isari, Koji*; Sekitani, Tetsuji*; Sekiguchi, Tetsuhiro; Tanaka, Kenichiro*

Journal of Electron Spectroscopy and Related Phenomena, 144-147, p.447 - 451, 2005/06

 Times Cited Count:5 Percentile:28.29(Spectroscopy)

no abstracts in English

Journal Articles

Thermal desorption behavior of deuterium implanted into polycrystalline diamond

Kimura, Hiromi*; Sasaki, Masayoshi*; Morimoto, Yasutomi*; Takeda, Tsuyoshi*; Kodama, Hiroshi*; Yoshikawa, Akira*; Oyaizu, Makoto*; Takahashi, Koji; Sakamoto, Keishi; Imai, Tsuyoshi; et al.

Journal of Nuclear Materials, 337-339, p.614 - 618, 2005/03

 Times Cited Count:6 Percentile:41.76(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Analysis of surface chemical reaction dynamics by using high brilliance and high energy-resolution synchrotron radiation

Teraoka, Yuden

Denki Gakkai Gijutsu Hokoku, (970), p.10 - 15, 2004/07

Si(001) surfaces are oxidized by O$$_{2}$$ molecules. The reaction schemes (oxide-layers formation, SiO desorption, their coexistence) are changed depending on the surface temperature and the gas pressure. The translational kinetic energy of incident O$$_{2}$$ molecules is recognizing to be an important parameter for controlling surface chemical reactions. The issues concerning translational kinetic energy induced oxidation by O$$_{2}$$ molecules at room temperature, effects of translational kinetic energy for SiO desorption processes at higher temperature than 1000 K, reaction mechanisms for coexistence of the SiO desorption and the oxide-layers formation in the temperature region from 900 K to 1000 K are reviewed.

Journal Articles

Ion desorption from DNA components irradiated with 0.5 keV ultrasoft X-ray photons

Fujii, Kentaro; Akamatsu, Ken; Yokoya, Akinari

Radiation Research, 161(4), p.435 - 441, 2004/04

 Times Cited Count:14 Percentile:39.1(Biology)

Positive ion desorption from thin films of DNA components, 2-deoxy-D-ribose, thymine, thymidine (dThd), and thymidine 5' -monophosphate (dTMP) has been investigated in the oxygen K-edge excitation region using synchrotron ultrasoft X-rays (538 eV). The mass patterns of dThd and dTMP, especially that of dTMP, were similar to that of 2-deoxy-D-ribose, indicating that a number of ions were generated at the sugar site, even in the nucleotide molecule. It is therefore it is predicted that the sugar is a more fragile site than the thymine base.

Journal Articles

Chemical reaction dynamics in oxidation processes of Si(001) surface at high temperature

Teraoka, Yuden; Yoshigoe, Akitaka; Moritani, Kosuke

Shinku, 47(4), p.301 - 307, 2004/04

Recent research results on translational kinetic energy effects of incident oxygen molecules for Si(001) oxidation are summalized and introduced. The variation of surface temperature dependence of SiO desorption yield, oxygen uptake curves, and chemical bonding states depending on translational kinetic energy of oxygen molecules is described concretely. Eapecially, the translational kinetic energy effects on chemical reaction processes of concurrent oxide-layers formation and SiO desorption are discussed.

Journal Articles

Fragmentation pathways caused by soft X-ray irradiation; The detection of desorption products using a rotatable time-of-flight mass-spectrometer combined with pulsed synchrotron radiation

Sekiguchi, Tetsuhiro; Baba, Yuji; Shimoyama, Iwao; Nath, K. G.

Free Electron lasers 2003, p.II_69 - II_70, 2004/00

no abstracts in English

Journal Articles

Element- and orientation-selective photo-fragmentation using polarized synchrotron radiation

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

JAEA Reports

Chemical state of tritium in Sr-Ce oxide ceramics and its removal characteristics (Cooperative research)

Nakamura, Hirofumi; Nishi, Masataka; Morita, Kenji*

JAERI-Research 2003-016, 32 Pages, 2003/08

JAERI-Research-2003-016.pdf:5.5MB

As a part of the detritiation study from the fusion reactor materials, chemical state of tritium injected into Sr-Ce base oxide ceramic proton conductor, which is a candidate for a tritium recovery system, was investigated with thermal desorption method. The results indicated that the oxide has to be heated up over 1300K to remove tritium due to the OT bond formation in the oxide. On the other hand, tritium removal behavior from the oxide were also investigated by exposing to humid air, and the mechanism of tritium removal from the oxide was identified by the dependency of tritium removal amount and chemical state on the humidity. The results revealed that tritium removal rate by the air exposure was low, and that almost tritium was removed as the vapor form, which was attributed to the isotope exchange reaction between the OT bond on the surface and the protium in vapor. It was also found that small amount of tritium was removed as elemental form under the humid air exposure, which could be attributed to the solute tritium in the oxide and oxygen absorption to the oxygen deficit in the oxide. As a result, the difference of the detritiation mechanism exposed to the humid air on the chemical state of tritium in the oxide was clarified, and it could be a useful basic data for the optimization of detritiation method.

Journal Articles

Coexistence of passive and active oxidation for O$$_{2}$$/Si(001) system observed by SiO mass spectrometry and synchrotron radiation photoemission spectroscopy

Teraoka, Yuden; Moritani, Kosuke; Yoshigoe, Akitaka

Applied Surface Science, 216(1-4), p.8 - 14, 2003/06

 Times Cited Count:6 Percentile:36.26(Chemistry, Physical)

The experiments concerning the oxidation of Si(001) were performed at the surface reaction analysis apparatus, installed at the beamline BL23SU in the SPring-8. The SiO desorb remarkably at surface temperature of 1000 K. The desorption yield increased with increasing the incident energy of O$$_{2}$$. On the other hand, the desorption yield increased with decreasing the incident energy in the temperature region lower than 1000 K. Oxygen uptake curves observed by O-1s photoemission measurements corresponded to the SiO desorption features. These facts reveal that the passive oxidation coexists with the SiO desorption in the temperature region from 900 K to 1000 K.

Journal Articles

Orientation effect on phot-fragmentation and ion-desorption from the topmost layers of molecular solids

Sekiguchi, Tetsuhiro; Ikeura, Hiromi*; Baba, Yuji

Surface Science, 532-535(1-3), p.1079 - 1084, 2003/06

Using a newly developed rotatable time-of-flight mass spectrometer(R-TOF-MS) and polarized synchrotron radiation, we have investigated orientation effect on fragmentation and desorption pathways occurring at the top-most layers of molecular solids. Reported will be polarization-angle dependencies of TOF mass spectra, high-resolution electron- and ion-NEXAFS in condensed formic acid, formamide and benzene. For condensed formamide(HCOND$$_{2}$$), marked orientation effect was observed for the enhanced H$$^{+}$$-yields following C1s $$rightarrow$$ $$sigma$$*$$_{C-H}$$ resonance. Direct photodissociation and charge-neutralization play an important role in the effect. For some fragment species, however, the bond scission showed no polarization dependence when dissociation sites were far from core-excited atoms. This is the case for N-D scission and D$$^{+}$$-desorption following C1s excitation, suggesting that indirect process governs, where secondary electrons would induce the fragmentation.

Journal Articles

Active control of chemical bond scission by site-specific core excitation

Wada, Shinichi*; Sumii, Ryohei*; Isari, Koji*; Waki, Satoshi*; Sako, Erika*; Sekiguchi, Tetsuhiro; Sekitani, Tetsuji*; Tanaka, Kenichiro*

Surface Science, 528(1-3), p.242 - 248, 2003/03

 Times Cited Count:44 Percentile:84.78(Chemistry, Physical)

no abstracts in English

Journal Articles

Active control of site specificity in ion desorption by core excitation

Wada, Shinichi*; Sako, Erika*; Sumii, Ryohei*; Waki, Satoshi*; Isari, Koji*; Sekiguchi, Tetsuhiro; Sekitani, Tetsuji*; Tanaka, Kenichiro*

Nuclear Instruments and Methods in Physics Research B, 199, p.361 - 365, 2003/01

 Times Cited Count:11 Percentile:60.77(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Control of O$$_{2}$$ adsorption and SiO desorption by incident energy of O$$_{2}$$ molecules in the O$$_{2}$$/Si(001) surface reaction system

Teraoka, Yuden; Yoshigoe, Akitaka; Moritani, Kosuke

Atomic Collision Research in Japan, No.29, p.68 - 70, 2003/00

There are two surface chemical reaction modes in the O$$_{2}$$/Si(001) system, that is, oxide-layers formation and SiO desorption. We have found that these reaction modes could be selected by changing translational kinetic energy of incident O$$_{2}$$ molecules.

JAEA Reports

Adsorption mechanisms and models of $$^{85}$$Sr, $$^{237}$$Np, $$^{238}$$Pu and $$^{241}$$Am in loess media (Joint research)

Tanaka, Tadao; Mukai, Masayuki; Maeda, Toshikatsu; Matsumoto, Junko; Ogawa, Hiromichi; Li, S.*; Wang, Z.*; Wang, J.*; Guo, Z.*; Zhao, Y.*

JAERI-Research 2002-034, 20 Pages, 2002/12

JAERI-Research-2002-034.pdf:1.1MB

Adsorption mechanisms and models of $$^{85}$$Sr(II), $$^{237}$$Np(V), $$^{238}$$Pu(IV) and $$^{241}$$Am(III) on the loess were investigated from their adsorption and desorption properties. The distribution coefficient of $$^{85}$$Sr and $$^{237}$$Np was 2 - 3 orders of magnitude smaller than that of $$^{238}$$Pu and $$^{241}$$Am. The adsorption of $$^{85}$$Sr and $$^{237}$$Np was mainly controlled by the ion exchange reaction. On the other hand, the adsorption of $$^{238}$$Pu and $$^{241}$$Am was mostly controlled by the selective chemical reactions with Fe and Mn oxyhydroxide/oxide and humic substances. On the basis of the experimental results, several types of adsorption models of the radionuclides, considering elemental concentrations, adsorption mechanisms and kinetics, were proposed for setting up the analytical systems of radionuclide migration in the loess media.

Journal Articles

Exchange of tritium implanted into oxide ceramics for protium by exposure to air vapors at room temperature

Morita, Kenji*; Suzuki, Hironori*; Soda, Kazuo*; Iwahara, Hiroiku*; Nakamura, Hirofumi; Hayashi, Takumi; Nishi, Masataka

Journal of Nuclear Materials, 307-311(2), p.1461 - 1465, 2002/12

 Times Cited Count:2 Percentile:17.6(Materials Science, Multidisciplinary)

no abstracts in English

69 (Records 1-20 displayed on this page)