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Journal Articles

Structure and optical properties of germanium implanted with carbon ions

Wei, P.; Xu, Y.; Nagata, Shinji*; Narumi, Kazumasa; Naramoto, Hiroshi

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.233 - 236, 2003/05

 Times Cited Count:6 Percentile:42.64(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Wide variety of flower-color and -shape mutants regenerated from leaf cultures irradiated with ion beams

Okamura, Masachika*; Yasuno, Noriko*; Otsuka, Masako*; Tanaka, Atsushi; Shikazono, Naoya; Hase, Yoshihiro

Nuclear Instruments and Methods in Physics Research B, 206, p.574 - 578, 2003/05

 Times Cited Count:93 Percentile:97.62(Instruments & Instrumentation)

Resent studies indicate that the ion beams have higher mutation frequency than low-LET radiations in plants but the difference in mutation spectrum still remains to be characterized. We investigated the efficiency of ion-beam irradiation combined with tissue culture in obtaining floral mutants. Leaves collected from carnation plants, cultivar Vital (cherry pink flowers with frilly petals), were irradiated with carbon ions or X-rays. They were cultured till the shoots regenerated. Sixteen mutants were obtained from 705 regenerated plants by carbon-ion irradiation. Those mutants were rich in variety, i.e., pink, dark pink, light pink, salmon, red, complex- and striped-color, and round and Dianthus-type petals were obtained. In contrast, 7 mutants obtained from 556 regenerated plants by X-rays were only pink, light pink and red. These results indicate that the ion beams could induce wider variety of flower-color and shape mutant than X-rays, and also indicate that the combined method of ion-beam irradiation with tissue culture is useful to obtain commercial varieties in a short time.

Journal Articles

Irradiation effect of different heavy ions and track section on the silkworm ${it bombyx mori}$

Tu, Z.; Kobayashi, Yasuhiko; Kiguchi, Kenji*; Watanabe, Hiroshi

Nuclear Instruments and Methods in Physics Research B, 206, p.591 - 595, 2003/05

no abstracts in English

Journal Articles

RBS and SEM analysis of the nickel-fullerene hybrid systems

Vacik, J.; Naramoto, Hiroshi; Narumi, Kazumasa; Yamamoto, Shunya; Abe, Hiroaki*

Nuclear Instruments and Methods in Physics Research B, 206, p.395 - 398, 2003/05

 Times Cited Count:9 Percentile:52.47(Instruments & Instrumentation)

no abstracts in English

Journal Articles

UV-ray photoelectron and ab initio band calculation studies on electronic structures of Cr- or Nb-ion implanted titanium dioxide

Umebayashi, Tsutomu; Yamaki, Tetsuya; Sumita, Taishi*; Yamamoto, Shunya; Tanaka, Shigeru; Asai, Keisuke*

Nuclear Instruments and Methods in Physics Research B, 206, p.264 - 267, 2003/05

 Times Cited Count:25 Percentile:82.19(Instruments & Instrumentation)

Chromium (Cr) and niobium (Nb) were implanted into single-crystalline titanium dioxide (TiO$$_{2}$$; rutile). After annealing at 600$$^{circ}$$C for the Cr-implanted sample or at 1000$$^{circ}$$C for the Nb-implanted sample, the radiation damage was recovered. The implanted metals occupied titanium (Ti) sites in TiO$$_{2}$$ to form metal-oxygen bonds. According to the ultraviolet-ray photoelectron spectra, a localized level due to the implanted metals was formed in band gap of both the crystals. This position was close to the VB edge for the Cr-doped TiO$$_{2}$$, while the Nb-doped TiO$$_{2}$$ had the small peak far from the edge. This is in good agreement with the ab-initio band calculation results. It is considered that the midgap states of Cr- and Nb-doped TiO$$_{2}$$ consist of the Cr t$$_{2g }$$ or Ti t$$_{2g }$$ state, respectively.

Journal Articles

Effects of implantation conditions on the luminescence properties of Eu-doped GaN

Nakanishi, Yasuo*; Wakahara, Akihiro*; Okada, Hiroshi*; Yoshida, Akira*; Oshima, Takeshi; Ito, Hisayoshi; Nakao, Setsuo*; Saito, Kazuo*; Kim, Y. T.*

Nuclear Instruments and Methods in Physics Research B, 206, p.1033 - 1036, 2003/05

 Times Cited Count:18 Percentile:73.56(Instruments & Instrumentation)

Photo luminescence properties of GaN implanted with Eu ions were studied. The GaN was epitaxialy grown on sapphire substrate. Multiple-implantation at RT was done to form box profile of Eu at a mean Eu concentration from 2.8$$times$$10$$^{19}$$ to 2.8$$times$$10$$^{20}$$/cm$$^{3}$$. Samples were annealed in NH$$_{3}$$, N$$_{2}$$ at 900-1050$$^{circ}$$C for 5-30 min after implantation. As the result, sharp emission peaks around 621nm which is assigned as 4f-4f transition were observed. The intensity of peaks increases with increasing Eu concentration and saturate at Eu concentrations around 2.8$$times$$10$$^{20}$$/cm$$^{3}$$.

Journal Articles

Observation of transient current induced in silicon carbide diodes by ion irradiation

Oshima, Takeshi; Lee, K. K.; Onoda, Shinobu; Kamiya, Tomihiro; Oikawa, Masakazu*; Laird, J. S.; Hirao, Toshio; Ito, Hisayoshi

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.979 - 983, 2003/05

 Times Cited Count:8 Percentile:49.76(Instruments & Instrumentation)

Ion beam induced current for pn SiC diode was observed by using MeV range ion beams.The diodes used in this study were pn diode fabricated on n-type epitaxial 6H-SiC. The p region was formed using Al-ion implantation at 800 $$^{o}$$C and subsequent annealing at 1800 $$^{o}$$C. The value of charge collection for diode applied to 30V by 12MeV-Ni microbeam irradiationis estimated to be (1.7-1.8)$$times$$10$$^{-13}$$Q from the analyzing transient-IBIC measurement.The efficiency of the charge collection is 85-93%.

Journal Articles

ESR characterization of activation of implanted phosphorus ions in silicon carbide

Isoya, Junichi*; Oshima, Takeshi; Oi, Akihiko; Morishita, Norio; Ito, Hisayoshi

Nuclear Instruments and Methods in Physics Research B, 206, p.965 - 968, 2003/05

 Times Cited Count:8 Percentile:49.76(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Ion beam modification of ZnO thin films on MgO

Matsunami, Noriaki*; Ito, Masaharu*; Takai, Yoshiaki*; Tazawa, Masato*; Sataka, Masao

Nuclear Instruments and Methods in Physics Research B, 206, p.282 - 286, 2003/05

 Times Cited Count:24 Percentile:81.09(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Proton radiation analysis of multi-junction space solar cells

Sumita, Taishi*; Imaizumi, Mitsuru*; Matsuda, Sumio*; Oshima, Takeshi; Oi, Akihiko; Ito, Hisayoshi

Nuclear Instruments and Methods in Physics Research B, 206, p.448 - 451, 2003/05

 Times Cited Count:58 Percentile:95.13(Instruments & Instrumentation)

Proton irradiation effects of triple-junction (InGaP/GaAs/Ge) solar cells for space use were studied. The changes in electrical and optical properties of the solar cells irradiated with protons at energies between 20 keV and 10 MeV were examined. As the result of analyzing the relationship between proton projection range and the degradation of their properties, the largest degradation of the properties was observed when proton projection range is near the junction of GaAs sub-cells. This indicates that improvement of the radiation resistance of GaAs is necessary to enhance radiation resistance of tliple-junction solar cells.

Journal Articles

Influence of carbon-ion irradiation and hydrogen-plasma treatment on photocatalytic properties of titanium dioxide films

Choi, Y.; Yamamoto, Shunya; Saito, Hiroshi*; Sumita, Taishi*; Ito, Hisayoshi

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.241 - 244, 2003/05

 Times Cited Count:7 Percentile:46.40(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Improvement of hydrogen absorption rate of Pd by ion irradiation

Abe, Hiroshi; Uchida, Hirohisa*; Azuma, Yorito*; Uedono, Akira*; Chen, Z. Q.*; Ito, Hisayoshi

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.224 - 227, 2003/05

 Times Cited Count:21 Percentile:77.57(Instruments & Instrumentation)

Palladium(Pd) is used for the purification of H$$_{2}$$ gas and as a catalyst for the dissociation of H$$_{2}$$ molecules. Therefore, much work has been made until now. Since low energy ion irradiation, i.e., ion implantation is quite useful for surface modification of materials, the hydrogen absorption properties of Pd is expected to be improved by ion irradiation. In this work, we aimed at investigating the effect of ion irradiation on the hydrogen absorption rate of Pd. Ion irradiation was made with H$$^{+}$$, He$$^{+}$$ and Ar$$^{+}$$ in an acceleration energy rage from 30 to 350keV up to a dose of 1 x 10$$^{17}$$ /cm$$^{2}$$. As a result, ion irradiated Pd sample was found to induce a higher absorption rate than that of the unirradiated one. The initial hydrogen results suggest that defects introduced in Pd by ion irradiation facilitate tha rate of nucleation and growth of hydride.

Journal Articles

Fabrication and stability of binary clusters by reactive molecular ion irradiation

Yamamoto, Hiroyuki; Saito, Takeru

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.42 - 46, 2003/05

 Times Cited Count:14 Percentile:66.01(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Dose dependence of the production yield of endohedral $$^{133}$$Xe-fullerene by ion implantation

Watanabe, Satoshi; Ishioka, Noriko; Shimomura, Haruhiko*; Muramatsu, Hisakazu*; Sekine, Toshiaki

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.399 - 402, 2003/05

 Times Cited Count:8 Percentile:49.76(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Characterization of metal-doped TiO$$_{2}$$ films by RBS/channeling

Yamamoto, Shunya; Yamaki, Tetsuya; Naramoto, Hiroshi; Tanaka, Shigeru

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.268 - 271, 2003/05

 Times Cited Count:13 Percentile:63.54(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Fluorine-doping in titanium dioxide by ion implantation technique

Yamaki, Tetsuya; Umebayashi, Tsutomu; Sumita, Taishi*; Yamamoto, Shunya; Maekawa, Masaki; Kawasuso, Atsuo; Ito, Hisayoshi

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.254 - 258, 2003/05

 Times Cited Count:139 Percentile:98.82(Instruments & Instrumentation)

Single crystalline titanium dioxide (TiO$$_{2}$$) rutile were implanted with 200keV F$$^{+}$$ at a nominal fluence of 1$$times$$10$$^{16}$$ to 1$$times$$10$$^{17}$$ ions cm$$^{-2}$$ and then thermally annealed in air up to 1200$$^{circ}C$$ for 5h. The radiation damage and its recovery during the subsequent annealing were analyzed by Rutherford backscattering spectrometry in channeling geometry and variable-energy positron annihilation spectroscopy. The lattice disorder was completely annealed at 1200$$^{circ}C$$ by the diffusion of point defects to the surface acting as a sink. According to the secondary ion mass spectrometry, the F depth profile was shifted to a shallower region along with the damage recovery, finally producing an F-doped layer where the impurity concentration increased steadily towards the surface. The F doping proved to provide a small modification to the conduction-band edge of TiO$$_{2}$$, as assessed by theoretical band calculations.

Journal Articles

Disordering in Li$$_{2}$$TiO$$_{3}$$ irradiated with high energy ions

Nakazawa, Tetsuya; Grismanovs, V.*; Yamaki, Daiju; Katano, Yoshio*; Aruga, Takeo

Nuclear Instruments and Methods in Physics Research B, 206, p.166 - 170, 2003/05

 Times Cited Count:33 Percentile:87.49(Instruments & Instrumentation)

Li$$_{2}$$TiO$$_{3}$$ samples with high energy oxygen ions were examined by the use of Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The Raman spectra of the irradiated samples do not show any evidence of destruction of Li$$_{2}$$TiO$$_{3}$$ structure. On the other hand, the Bragg peak intensity of XRD is decreased with the increasing the ion fluence. Especially, the intensity of (002) supercell peak is drastically reduced after the irradiation to 1.2E+19 ions/m$$^{2}$$. This result implies that partial site mixing between Li and Ti atoms is induced by the irradiation. The transition to such a disordering is observed also by SEM examination; the grain structure at surface layer is vanished after the irradiation.

Journal Articles

Characterization of air-exposed surface $$beta$$-FeSi$$_{2}$$ fabricated by ion beam sputter deposition method

Saito, Takeru; Yamamoto, Hiroyuki; Yamaguchi, Kenji; Nakanoya, Takamitsu; Hojo, Kiichi; Haraguchi, Masaharu*; Imamura, Motoyasu*; Matsubayashi, Nobuyuki*; Tanaka, Tomoaki*; Shimada, Hiromichi*

Nuclear Instruments and Methods in Physics Research B, 206, p.321 - 325, 2003/05

 Times Cited Count:7 Percentile:46.40(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Effect of surface treatment of Si substrate on the crystal structure of FeSi$$_{2}$$ thin film formed by ion beam sputter deposition method

Haraguchi, Masaharu*; Yamamoto, Hiroyuki; Yamaguchi, Kenji; Nakanoya, Takamitsu; Saito, Takeru; Sasase, Masato*; Hojo, Kiichi

Nuclear Instruments and Methods in Physics Research B, 206, p.313 - 316, 2003/05

 Times Cited Count:17 Percentile:71.86(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Laser detection of surface acoustic waves as a method of measuring an Ar ion beam modification of carbon thin film

Kitazawa, Shinichi; Putra, P.; Sakai, Seiji; Narumi, Kazumasa; Naramoto, Hiroshi; Yamamoto, Shunya; Chiba, Atsuya

Nuclear Instruments and Methods in Physics Research B, 206, p.952 - 955, 2003/05

 Times Cited Count:6 Percentile:42.64(Instruments & Instrumentation)

Pulsed energy impacts are expected to generate the elastic waves reflecting the elastic properties of impacted substances. Among the generated waves, the surface acoustic waves (SAW) can be more specific to the surface structures and can be used effectively in the characterization of thin films in a non-destructive way. In the present study, pulsed laser impacts were employed to generate SAWs on a thin film and the SAWs are detected with a laser reflection technique. To test the effectiveness of this method, an amorphous carbon films were irradiated with 13 keV Ar ions at room temperature in a broad range and the SAW propagation velocity was evaluated as a function of Ar ion dose. The present preliminary experiment using pulsed laser suggests the successful detection of SAW from typical substances with different modulus of elasticity such as fcc metals, oxides and semi conducting materials.

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