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Journal Articles

Nuclear structure of elements with $$100 le Z le 109$$ from alpha spectroscopy

Asai, Masato; He${ss}$berger, F. P.*; Lopez-Martens, A.*

Nuclear Physics A, 944, p.308 - 332, 2015/12

 Times Cited Count:43 Percentile:95.08(Physics, Nuclear)

Nuclear structure of Z = 100-109 nuclei studied through $$alpha$$-decay spectroscopy have been reviewed. Experimental techniques and methods concerning separation techniques, summing effects in $$alpha$$ spectra, and the use of digital electronics for $$alpha$$-decay spectroscopy have been described in detail. The presentation of the experimental results and the physics discussion were focused on nuclear structure systematics in even-Z nuclei along the N = 151, 153, and 155 isotonic lines, where most progress has been achieved in the last 10 years.

Journal Articles

Investigation of the fragmentation of core-ionised deoxyribose; A Study as a function of the tautomeric form

Herv$'e$ du Penhoat, M.-A.*; Kamol Ghose, K.*; Gaigeot, M.-P.*; Vuilleumier, R.*; Fujii, Kentaro; Yokoya, Akinari; Politis, M.-F.*

Physical Chemistry Chemical Physics, 17(48), p.32375 - 32383, 2015/12

 Times Cited Count:8 Percentile:36.13(Chemistry, Physical)

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:12.11(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:26.95(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:18.24(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:58.59(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:28.32(Spectroscopy)

no abstracts in English

Journal Articles

Production mechanism of DNA bases radical induced by inner-shell excitation

Yokoya, Akinari

Hoshako, 17(3), p.111 - 117, 2004/05

To reveal the mechanism of oxidative base damages, such as 8-oxo-G, in DNA molecule by ionizing radiation, DNA base radicals were examined around oxygen and nitrogen K-edge region using an EPR spectrometer installed in a synchrotron soft X-ray beamline (BL23SU) in SPring-8. In situ measurements of EPR spectrum of guanine base revealed that short-lived transient radical species are specifically induced by photoexcitation of a 1s electron to $$sigma$$* antibonding orbital at carbonyl oxygen atom. They promptly disappear by "beam-off". On the other hand, a long-lived radical whose EPR spectrum is consistent with previous reports for guanine cation radical was accumulated during the irradiation. The yield of the stable radical decreased by These results indicate that chemically stable DNA base lesions, such as 8-oxo-G, would result from transient species that are inferred to be one electron oxidized radicals after decay of Auger final state.

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

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:84.82(Chemistry, Physical)

no abstracts in English

Journal Articles

Electron paramagnetic resonance induced by K-shell resonance excitation in DNA bases in solid state

Yokoya, Akinari; Akamatsu, Ken*; Fujii, Kentaro

Nuclear Instruments and Methods in Physics Research B, 99, p.366 - 369, 2003/01

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:60.84(Instruments & Instrumentation)

no abstracts in English

Journal Articles

First measurement of the quadrupole moment in the 2$$_1^+$$ state of $$^{84}$$Kr

Osa, Akihiko; Czosnyka, T.*; Utsuno, Yutaka; Mizusaki, Takahiro*; Toh, Yosuke; Oshima, Masumi; Koizumi, Mitsuo; Hatsukawa, Yuichi; Katakura, Junichi; Hayakawa, Takehito; et al.

Physics Letters B, 546(1-2), p.48 - 54, 2002/10

 Times Cited Count:10 Percentile:51.87(Astronomy & Astrophysics)

A $$^{84}$$Kr beam was Coulomb-excited on a $$^{98}$$Mo target and a $$^{nat}$$Ta target. Six reduced matrix elements for 5 low-lying states were derived from the analysis using the least-squares code GOSIA. The quadrupole moment of the 2$$_1^+$$ was newly obtained. The measured quadrupole moment and the $$B(E2)$$ values are consistent with large-scale shell-model calculations which give a systematic description of $$N$$,=,50 isotones.

Journal Articles

Fragment-ion desorption from sulfur-containing amino acids by localized core-level excitation

Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao

Surface Review and Letters, 9(1), p.77 - 83, 2002/02

 Times Cited Count:4 Percentile:26.78(Chemistry, Physical)

no abstracts in English

Journal Articles

Reparability of lethal lesions produced by phosphorus photoabsorption in yeast cells

Usami, Noriko*; Yokoya, Akinari; Ishizaka, Shozo*; Kobayashi, Katsumi*

Journal of Radiation Research, 42(3), p.317 - 331, 2001/09

 Times Cited Count:8 Percentile:28.96(Biology)

The characteristics of DNA lesions produced by the phosphorus K-shell absorption in yeast cells were studied using monochromatized soft X-rays tuned to the phosphorus K-edge peak (2153 eV) and below the peak energy (2147 eV). The repaired fractions of DNA double-strand breaks (dsb) were measured relatively by using both a mutant, (${it rad 54-3}$), which shows the temperature-sensitive dsb repair-deficient, and a wild-type strain. The repaired fraction of lesion in ${it rad 54-3}$, which corresponds to the relative yield of dsb reparable by the ${it RAD 54}$ pathway, was not affected by the phosphorus photoabsorption. Repair of the produced lesions in the wild-type cells was also measured by comparing the surviving fraction of the immediately plated cells to that of those cells plated after holding in a non-nutrient medium for 80 hrs. The recovery of the surviving fraction after the holding treatment was dependent upon the soft X-ray energy. These results suggest that irrepairable lesions are produced by the inner-shell photoabsorption of phosphorus in DNA, although its yield is small.

Journal Articles

Inner shell excitation and dissociation of condensed formamide

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

Applied Surface Science, 169-170, p.282 - 286, 2001/01

 Times Cited Count:8 Percentile:45.68(Chemistry, Physical)

Carbon and nitrogen K-shell excitation and dissociation of condensed formamide at 96 K were studied by near edge X-ray absorption fine structure (NEXAFS) recorded by total electron yield (TEY), total ion yield (TIY) and photon-stimulated desorption (PSD) yield of H+ measurements. It was found that electronic transitions from the C1s or the N1s to the $$sigma$$*(C-H) and/or (N-H) enhanced ion yield of H+ from the C-H and/or N-H functional group. This selective dissociation indicates that the corresponding unoccupied molecular orbital has an antibonding character of the C-H and/or N-H. To investigate the molecular orientation of condensed formamide, incidence-angle-dependent TEY-NEXAFS spectra were measured. The CNO plane of the adsorbed formamide molecule is determined to be tilted away from the surface by an averaged angle of about 42 degrees.

Journal Articles

Site-specific fragmentation of acetone adsorbates on Si(100) in the carbon 1s absorption edge

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

Surface Science, 454-456, p.363 - 368, 2000/05

 Times Cited Count:23 Percentile:73.11(Chemistry, Physical)

no abstracts in English

Journal Articles

Desorption of fragment ions from condensed Si(OCH$$_{3}$$)$$_{4}$$ by localized inner-shell electron excitation at the silicon, oxygen and carbon K-edges

Baba, Yuji; Sekiguchi, Tetsuhiro

Journal of Vacuum Science and Technology A, 18(2), p.334 - 337, 2000/03

 Times Cited Count:4 Percentile:23.55(Materials Science, Coatings & Films)

no abstracts in English

66 (Records 1-20 displayed on this page)