Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Fujii, Kentaro; Shikazono, Naoya; Yokoya, Akinari
no journal, ,
In order to verify the possibility of selective damage induction in DNA, the yields of base lesions as well as strand breaks have been measured in dry plasmid DNA films irradiated with highly monochromatized soft X-rays in the energy region of 270-760eV. The experiments were performed at the beamline BL23SU in the SPring-8. The yields of base lesions were determined by the post-irradiation-treatment of the DNA with enzymatic probes (Fpg and Endo III) which excise base lesion. The yields of both pyrimidine and purine base lesions, observed as Nth-sensitive and Fpg-sensitive sites, respectively, are strikingly high at the oxygen K-edge (560eV) but extremely low at an energy just below the nitrogen K-edge (380eV) as compared with the yields observed at other photon energies.
Yokoya, Akinari; Fujii, Kentaro; Fukuda, Yoshihiro; Ukai, Masatoshi*
no journal, ,
In order to clarify the photoelectric effect of nitrogen and oxygen atom on DNA damage induction and succeeding mutation induction, unpaired electron species produced in DNA and nucleobases have been studied using an electron paramagnetic resonance (EPR) spectrometer. Thin films of calf thymus DNA and evaporated thymine and cytosine bases were irradiated in the EPR cavity installed in vacuum chamber connected to a soft X-ray beamline in SPring-8 (BL23SU) with synchrotron soft X-rays around nitrogen and oxygen K-edge. Short-lived EPR signals were observed only during irradiation. The photon energy dependences of the yield of these short-lived species arising in nucleobase films are very similar to those of fine structure of photoabsorption spectra (XANES), though that for DNA film is different from XANES of DNA. The origin of these short-lived species will be discussed.
Agui, Akane; Matsumoto, Sayaka*; Sakurai, Yoshiharu*; Ito, Masayoshi*; Homma, Satoshi*; Tsuji, Naruki*; Sakurai, Hiroshi*
no journal, ,
no abstracts in English
Mizumaki, Masaichiro*; Agui, Akane; Uozumi, Takayuki*; Inoue, Akira*; Kawai, Masanori*; Ichikawa, Noriya*; Shimakawa, Yuichi*
no journal, ,
no abstracts in English
Izumi, Yudai*; Imazu, Akiko*; Mimoto, Aki*; Tanabe, Maiko*; Nakagawa, Kazumichi*; Tanaka, Masahito*; Agui, Akane; Muro, Takayuki*
no journal, ,
no abstracts in English
Koike, Masato; Imazono, Takashi; Kawachi, Tetsuya
no journal, ,
When the conventional X-ray multilayer is used to enhance the diffraction efficiency of diffraction gratings the incidence and diffraction angles are varied with the wavelength to satisfy both grating equation and extended Bragg condition. We present a new scheme to widen the available wavelength range by use of the 5 sets of multilayers in the energy range of 2-3.8 keV (0.33-0.62 nm) in the condition of a fixed incidence angle, and discuss about the calculated diffraction efficiency.
Imazono, Takashi; Sano, Kazuo*; Suzuki, Yoji; Kawachi, Tetsuya; Koike, Masato
no journal, ,
no abstracts in English
Mannan, M. A.; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Hirao, Norie; Narita, Ayumi; Nagano, Masamitsu*; Noguchi, Hideyuki*
no journal, ,
The electronic structure and molecular orientation of polydimethylsilane (PDMS) film evaporated on indium tin oxide (ITO) surface have been assigned. The film has been synthesized by high vacuum electron bombardment evaporation technique. The orientation and electronic structure of the film as well as those of the annealed sample were studied by Si K-edge NEXAFS and X-ray photoelectron spectroscopy. The Si K-edge NEXAFS spectra for the thick film have at least four resonance peaks of which two peaks are found to be strongly polarization dependent. The lower-energy resonance peak at 1842.0 eV has short-axis polarization corresponding to the resonance excitation from Si 1s to s* (pyz), and the higher-energy resonance peak at 1843.2 eV has long-axis polarization due to the excitation of Si 1s to s* (px). On the basis of the polarization dependences, it is revealed that the backbones of the PDMS polymers are perpendicularly oriented to the ITO surface.
Honda, Mitsunori; Yasuda, Ryo; Hayashida, Hirotoshi; Nojima, Takehiro; Iikura, Hiroshi; Sakai, Takuro; Matsubayashi, Masahito
no journal, ,
no abstracts in English
Fujimori, Shinichi; Kawasaki, Ikuto; Yasui, Akira; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika
no journal, ,
We have studied electronic structure of uranium compounds such as itinerant 5
compound UFeGa
, localized 5 compound UPd
, and heavy Fermion superconductors UPd
Al, UNiAl, URuSi, UPt. The obtained photoemission spectra have been compared with the results of the band structure calculations. Their U5 electronic structures have been discussed.
Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Uddin, M. N.*; Nagano, Masamitsu*
no journal, ,
Graphite-like boron carbonitride (B-C-N) have been expected to control a wide variety of electronic properties. However, complicated chemical bonding make it difficult to analyze the atomic arrangement between B, C and N has not been well clarified. We used NEXAFS spectroscopy for characterization of local structures of B-C-N thin films. In both B and N K-edge NEXAFS spectra, some 
*peaks of B-C-N compounds and the * peaks of hexagonal boron nitride (h-BN) appeared with graphite-like polarization dependence. We calculated partial density of states (PDOS) of B and N sites in some models clusters of graphite-like B-C-N by ab initio molecular orbital calculation. Based on the comparison of theoretical results with NEXAFS spectra, we propose a rule that B, C, and N atoms are arranged not to inhibit interatomic polarization between B and N sites in graphite-like structures.
Okajima, Yuka; Yoneda, Yasuhiro; Saito, Hiroyuki; Nisawa, Atsushi*; Yamamoto, Masaki*; Goto, Shunji*
no journal, ,
no abstracts in English
Matsumura, Daiju; Okajima, Yuka; Nishihata, Yasuo; Mizuki, Junichiro; Taniguchi, Masashi*; Uenishi, Mari*; Tanaka, Hirohisa*
no journal, ,
Metal particles used in the catalytic reaction are made fine in order to spread the surface area. However, it is expected that the nanometer-sized metal particles show the original catalytic reaction which is different from that for the larger particles. In order to study the originality of the fine particles, detailed structure, shape and electronic informations will be required. Dispersive XAFS system enables us to observe the fine particles with high precise information. We used this method for the study of the changes in the Pd metal fine particles during CO/NO catalytic reaction. As a result, the expansion-contraction, aggregation-dispersion and oxidation-reduction changes in the Pd metal fine particles have been revealed by direct observation of dispersive XAFS method.
Narita, Ayumi; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Hirao, Norie; Yaita, Tsuyoshi
no journal, ,
no abstracts in English
Hirao, Norie; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Honda, Mitsunori; Narita, Ayumi
no journal, ,
no abstracts in English
Yoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
To realize the in-situ real-space observation of surface reactions on solid surfaces with atomic resolutions, the scanning probe microscope has been installed to SUREAC2000 at the BL23SU in the SPring-8 and its performance is reported. After cleaning the Si(111) substrate by annealing, the corner holes of the 7
7 structure was stably observed and the defects and the adsorbates were clearly confirmed. We succeeded the in-situ real-space observation with atomic resolutions at the synchrotron radiation beamline.
7 surface enhanced by translational kinetic energy of OYoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
We clarified the initial sticking probability of O on Si(111)-77 surface varied with the translational kinetic energy of O by observing the time evolution of the oxygen bonding configurations and the Si oxidation states. It is found that the reaction probability of the ins oxygen is dominantly changed by the translational kinetic energy O.
7 surface at 300 K by using LEED, STM and synchrotron radiation XPSYoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
The coexistence of oxides and the 7x7 structure in the oxidation of the Si(111)-77 surface is confirmed by the real-time SR-XPS, LEED and STM measurements.
moleculesHarries, J.; Yoshigoe, Akitaka; Teraoka, Yuden
no journal, ,
A supersonic beam of molecular nitrogen was used to nitridate an Al(111) surface. The uptake of nitrogen was monitored using synchrotron radiation photoelectron spectroscopy. The nitrogen uptake curve for a beam energy of 2.0 eV, higher than the threshold energy of 1.8 eV, was linear, indicating that the nitrogen penetrates into the bulk. Elementa depth distributions have been generated from angular-resolved photoelectron spectra.
Haruyama, Yuichi*; Teraoka, Yuden; Matsui, Shinji*
no journal, ,
An alloy of TiVCr system is a solid-sulution type three elements alloy with a BCC crystal structure. It is known as a hydrogen storage material. The amount of hydrogen storage is about 2.3w%. It is relatively larger comparing to that of other hydrogen storage metals. Prior to hydrogen storage, an initial activation process is needed to change its surface atomic structure. We performed inner-shell photoemission spectroscopy, balence band photoemission spectroscopy, and X-ray absorption near-edge spectroscopy measurements to study an electronic structure and effects of hydrogen absorption in a hydrogen storage alloy such as the Ti
V
Cr
. Furthermore, thermal annealing effects of them were investigated. With increasing thermal anneal temperature, photoemission intensity of Ti increased comparing to V and Cr. This fact implies that Ti segregates near surface by thermal annealing.