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Journal Articles

Study on selective adsorption of deuterium on boron nitride using photon-stimulated ion-desorption

Koswattage, K.; Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nakagawa, Kazumichi*

Applied Surface Science, 258(4), p.1561 - 1564, 2011/12

 Times Cited Count:5 Percentile:71.34(Chemistry, Physical)

Adsorption behavior of atomic deuterium on a hexagonal boron nitride (h-BN) thin film is studied by photon-stimulated ion desorption (PSID) of D$$^{+}$$ and near edge X-ray absorption fine structure (NEXAFS) at the B and N K-edges. After the adsorption of atomic deuterium, D$$^{+}$$ desorption yield $$eta$$(h$$nu$$) shows clear enhancement at the B K-edge and almost no enhancement at the N K-edge. NEXAFS spectra show a large change in the B K-edge and a small change in the N K-edge after the adsorption. We propose selective adsorption of atomic deuterium on the h-BN thin film based on the experimental results, and mention the effectiveness of applying the PSID method with X-ray to study hydrogen storage materials.

Journal Articles

Selective adsorption of atomic hydrogen on a $$h$$-BN thin film

Koswattage, K.; Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nakagawa, Kazumichi*

Journal of Chemical Physics, 135(1), p.014706_1 - 014706_12, 2011/07

 Times Cited Count:18 Percentile:39.39(Chemistry, Physical)

The adsorption of atomic hydrogen on hexagonal boron nitride ($$h$$-BN) is studied using two element-specific spectroscopies, i.e., near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS). B K-edge NEXAFS spectra show a clear change in the energy region of the $$pi$$$$^{*}$$ band before and after reaction with atomic deuterium. On the other hand, N K-edge NEXAFS spectra show only a little change. B 1s XPS spectra show a distinct component at the low binding energy side of a main component, while N 1s XPS spectra show peak broadening at the high binding energy side. These experimental results are analyzed by the discrete variational (DV) X$$alpha$$ method with a core-hole effect and are explained by a model in which hydrogen atoms are preferentially adsorbed on the B sites of $$h$$-BN. Based on the experimental and theoretical results, we propose a site-selective property of BN material on adsorption of atomic hydrogen.

Journal Articles

Event structure and double helicity asymmetry in jet production from polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 84(1), p.012006_1 - 012006_18, 2011/07

 Times Cited Count:23 Percentile:28.31(Astronomy & Astrophysics)

We report on the event structure and double helicity asymmetry ($$A_{LL}$$) of jet production in longitudinally polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. Photons and charged particles were measured by the PHENIX experiment. Event structure was compared with the results from PYTHIA event generator. The production rate of reconstructed jets is satisfactorily reproduced with the next-to-leading-order perturbative QCD calculation. We measured $$A_{LL}$$ = -0.0014 $$pm$$ 0.0037 at the lowest $$P_T$$ bin and -0.0181 $$pm$$ 0.0282 at the highest $$P_T$$ bin. The measured $$A_{LL}$$ is compared with the predictions that assume various $$Delta G(x)$$ distributions.

Journal Articles

Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

 Times Cited Count:144 Percentile:0.61(Physics, Nuclear)

Transverse momentum distributions and yields for $$pi^{pm}, K^{pm}, p$$, and $$bar{p}$$ in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different $$sqrt{s}$$ collisions. We also present the scaling properties such as $$m_T$$ and $$x_T$$ scaling and discuss the mechanism of the particle production in $$p + p$$ collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 Times Cited Count:8 Percentile:46(Physics, Nuclear)

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled $$p+p$$ collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to $$p+p$$ collisions.

Journal Articles

Measurement of neutral mesons in $$p$$ + $$p$$ collisions at $$sqrt{s}$$ = 200 GeV and scaling properties of hadron production

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 83(5), p.052004_1 - 052004_26, 2011/03

 Times Cited Count:140 Percentile:1.52(Astronomy & Astrophysics)

The PHENIX experiment at RHIC has measured the invariant differential cross section for production of $$K^0_s$$, $$omega$$, $$eta'$$ and $$phi$$ mesons in $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. The spectral shapes of all hadron transverse momentum distributions are well described by a Tsallis distribution functional form with only two parameters, $$n$$ and $$T$$, determining the high $$p_T$$ and characterizing the low $$p_T$$ regions for the spectra, respectively. The integrated invariant cross sections calculated from the fitted distributions are found to be consistent with existing measurements and with statistical model predictions.

Journal Articles

Clinical review of the Japanese experience with boron neutron capture therapy and a proposed strategy using epithermal neutron beams

Nakagawa, Yoshinobu*; Pooh, K. H.*; Kobayashi, Toru*; Kageji, Teruyoshi*; Uyama, Shinichi*; Matsumura, Akira*; Kumada, Hiroaki

Journal of Neuro-Oncology, 62(1), p.87 - 99, 2003/04

 Times Cited Count:106 Percentile:17.95

Our concept of boron neutron capture therapy (BNCT) is selective destruction of tumor cells using the heavy-charged particles Yielded through 10B(n, alpha)7 Li reactions. In the analysis of side effects due to radiation, we included all the 159 patients treated between 1977 and 2001. With respect to the radiation dose (i.e. physical dose of boron n-alpha reaction), the new protocol prescribes a minimum tumor volume dose of 15Gy or, alternatively, a minimum target volume dose of 18Gy. The maximum vascular dose should not exceed 15Gy (physical dose of boron n-alpha reaction) and the total amount of gamma rays should remain below 10Gy, including core gamma rays from the reactor and capture gamma in brain tissue. The outcomes for 10 patients who were treated by the new protocol using a new mode composed of thermal and epithermal neutrons are reported.

Journal Articles

Clinical review of boron neutron capture therapy and a proposed strategy using epithermal neutron beams in Japan

Nakagawa, Yoshinobu*; Pooh, K. H.*; Kageji, Teruyoshi*; Uyama, Shinichi*; Kobayashi, Toru*; Sakurai, Yoshinori*; Matsumura, Akira*; Yamamoto, Tetsuya*; Kumada, Hiroaki

Research and Development in Neutron Capture Therapy, p.1113 - 1116, 2002/09

To make a new protocol using epithermal neutron beam for high-grade glioma patients, we elucidated the relationship between the radiation dose, histological tumor grade, and clinical outcome. One hundred and eighty-three patients with kinds of brain tumors were treated by BNCT since 1968, however, we performed a retrospective study of 105 patients with glial tumors treated in Japan between 1978 and 1997. As for the radiation side effect, we analyzed all patients(n=159) treated between 1977 and 2001. Ten patients with glioblastoma were treated according to the new protocol using epithermal neutron.

Journal Articles

Intraoperative boron neturon capture therapy for malignant gliomas; First clinical results of Tsukuba phase I/II trial using JAERI mixed thermal-epithermal beam

Matsumura, Akira*; Yamamoto, Tetsuya*; Shibata, Yasushi*; Akutsu, Hiroyoshi*; Yasuda, Susumu*; Matsushita, Akira*; Nakai, K.*; Yamada, Takashi*; Takano, Shingo*; Mizutani, Taro*; et al.

Proceedings of 9th International Symposium on Neutron Capture Therapy for Cancer, p.29 - 30, 2000/10

no abstracts in English

Journal Articles

Advanced SSTR

Kikuchi, Mitsuru; Seki, Yasushi; K. Nakagawa*

Fusion Engineering and Design, 48(3-4), p.265 - 270, 2000/09

 Times Cited Count:18 Percentile:24.34

no abstracts in English

Journal Articles

Generation of low-frequency electromagnetic waves by spectrally broad intense laser pulses in a plasma

Tsintsadze, L. N.; Tajima, Toshiki; Nishikawa, K.*; Koga, J. K.; Nakagawa, Keisuke*; Kishimoto, Yasuaki

Physica Scripta, T84, p.94 - 97, 2000/04

 Times Cited Count:5 Percentile:56.23(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Hybrid monitoring system for high temperature gas cooling reactor

Nabeshima, Kunihiko; Tuerkcan, E.*; Suzudo, Tomoaki; Nakagawa, Shigeaki; Inoue, K.*; Oono, Tomio*; *; Suzuki, Katsuo

Proc. of Human-Computer Interaction International'99, 2, p.1187 - 1191, 1999/00

no abstracts in English

Journal Articles

High-Temperature engineering Test Reactor door valve monitor system

H.O.Menlove*; M.E.Abhold*; D.H.Beddingfield*; K.E.Kroncke*; J.Baca*; Nakagawa, Shigeaki

LA-13421-M, p.1 - 49, 1998/06

no abstracts in English

Oral presentation

Study of hydrogen adsorption and desorption on boron nitride thin films by X-ray photoelectron spectroscopy

Kosuwattage, K.; Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nakagawa, Kazumichi*

no journal, , 

B-C-N nanomaterials have attracted attention for hydrogen storage. We investigated adsorption and desorption of hydrogen on hexagonal boron nitride (h-BN) and graphite thin films which were chosen as basic systems of the B-C-N nanomaterials using XPS. Epitaxial thin films of h-BN and graphite were deposited on Ni(111) surfaces by CVD method, and were exposed to atomic hydrogen. B 1s and N 1s spectra of h-BN thin films and C 1s spectra of graphite thin films showed peak shifting and peak broadening after hydrogen treatments. We quantitatively compared hydrogenation for h-BN and graphite thin films through peak fitting analysis, and obtained preliminary result that h-BN may have larger degree of hydrogenation larger than graphite. We also studied the hydrogen desorption properties and found that the initiation temperature of desorption for h-BN is similar to the case of graphite. These results suggest that BN-based material can be a potential material for hydrogen storage.

Oral presentation

Site selective adsorption of atomic deuterium on BN thin film

Koswattage, K.; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Baba, Yuji; Nakagawa, Kazumichi*

no journal, , 

Boron nitride (BN) attracts attention for hydrogen storage because of nanotube structure and large interaction with hydrogen. Chemical adsorption of atomic hydrogen is interesting for hydrogen storage at room temperature. However, experimental research on the interaction of atomic hydrogen is little due to the difficulty in synthesizing BN nanomaterials. In this work, we studied adsorption of atomic deuterium on a BN thin film as model system of BN nanotubes with diameter of infinity using NEXAFS spectroscopy. BN thin film was formed on Ni(111) surface by exposure of borazine gas at 800 $$^{circ}$$C. We measured NEXAFS for the BN film before and after reaction with atomic deuterium produced by a tungsten hot filament. While NEXAFS spectra showed clear change at B K-edge, little change was observed at N K-edge. We analyzed these results by density functional theory calculations and clarified that atomic deuterium preferentially adsorbs on B site in BN materials.

Oral presentation

Site-selective adsorption of atomic deuterium on a hexagonal boron nitride thin film

Koswattage, K.; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Baba, Yuji; Nakagawa, Kazumichi*

no journal, , 

Boron-nitride (BN) has attracted much attention as a promising candidate for hydrogen storage. Recently, some theoretical efforts have predicted that BN materials have site selectivity on adsorption of atomic hydrogen. However, adsorption structure is still controversial because of inconsistent theoretical reports. In this work, we used NEXAFS and XPS to study adsorption behavior of atomic deuterium on a hexagonal BN thin film as a model system of BN nanotubes. After deuteration, B K-edge NEXAFS spectra showed clear change in between the first $$pi$$* and $$sigma$$* resonant peaks. On the other hand, N K-edge spectra showed only slight change. XPS of B 1s showed a prominent shoulder on the low binding energy side after deuteration, in contrast to N 1s showed mere peak broadening at the high binding energy side. These results were analyzed by DV-X$$alpha$$ method. Finally, we concluded that hydrogen is preferentially adsorbed on B sites of BN materials.

Oral presentation

Site-selective adsorption of atomic deuterium on BN thin film

Koswattage, K.; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Nakagawa, Kazumichi*

no journal, , 

no abstracts in English

Oral presentation

Selective adsorption of atomic deuterium on BN thin film

Koswattage, K.; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Baba, Yuji; Nakagawa, Kazumichi*

no journal, , 

no abstracts in English

Oral presentation

Selective adsorption of atomic deuterium on BN thin film

Koswattage, K.; Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nakagawa, Kazumichi*

no journal, , 

Boron nitride (BN) nanotubes (BNNTs) have attracted much research attention as a promising candidate for hydrogen storage. One of the most basic arguments is the site dependence of atomic hydrogen adsorption. In this work, we investigated the site dependence of atomic deuterium adsorption on a thin film of BN as a representative system for BN nanomaterials, using NEXAFS and XPS. A BN thin. The XPS spectrum of B 1s showed a prominent shoulder on the low binding energy side of the main peak after deuteration, while the N 1s spectrum showed only peak broadening at the high binding energy side. In the PSID measurements, it was observed that there was a clear resonance peak at the B site but no resonance at the N site. The experimental results of NEXAFS and XPS were analyzed by the DV-X$$alpha$$ method with core-hole effect. Finally, we conclude that deuterium (hydrogen) atoms are preferentially adsorbed on the B sites of BN materials, via a single hydrogen adsorption model.

Oral presentation

Hydrogen adsorption behavior of h-BN thin film on Ni(111)

Koswattage, K.; Shimoyama, Iwao; Baba, Yuji; Sekiguchi, Tetsuhiro; Nakagawa, Kazumichi*

no journal, , 

no abstracts in English

22 (Records 1-20 displayed on this page)