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Kitamura, Akane; Sato, Takahiro; Koka, Masashi; Kobayashi, Tomohiro*; Kamiya, Tomihiro
Nuclear Instruments and Methods in Physics Research B, 307, p.610 - 613, 2013/07
Times Cited Count：6 Percentile：44.02(Instruments & Instrumentation)Kitamura, Akane; Kobayashi, Tomohiro*; Sato, Takahiro; Koka, Masashi; Kamiya, Tomihiro; Suzuki, Akihiro*; Terai, Takayuki*
Nuclear Instruments and Methods in Physics Research B, 307, p.614 - 617, 2013/07
Times Cited Count：7 Percentile：49.28(Instruments & Instrumentation)Abe, Hiroshi; Orimo, Satoshi; Kishimoto, Masahiko*; Aone, Shigeo*; Uchida, Hirohisa*; Daido, Hiroyuki; Oshima, Takeshi
Nuclear Instruments and Methods in Physics Research B, 307, p.218 - 220, 2013/07
Times Cited Count：1 Percentile：11.54(Instruments & Instrumentation)We investigated the structure changes of a hydrogen storage alloy by ion irradiations, and its absorption property in order to obtain basic data and to elucidate relevant mechanisms of hydrogen absorption by the influence of the irradiation. In previous studies, the induction of vacancies in a hydrogen absorption alloy was found to be effective to increase in the hydrogen absorption rate. As well known, the rate of hydrogen absorption strongly depends upon the surface state of a hydrogen storage alloy because the dissociation of hydrogen molecules or water molecules needs electron change with the surface in the H
gas or electrochemical reaction process. In this study, ion irradiations were made at a room temperature using the laser driven proton beam method, at Kansai Photon Science Institute, Japan Atomic Energy Agency. The beam treatment has several unique properties such as short pulse duration, high peak current, low transverse emittance, and wide energy range from KeV to MeV. The irradiation was used to modify the alloy surface using this equipment. From obtained results, the initial hydrogen absorption rate was found improved by the laser driven proton beam rather more effectively than a mono-energetic proton beam. Discussion is made on the correlation among proton irradiation (laser driven proton or mono-energetic proton) and the initial hydrogen absorption rate of the alloy. We argue about the usefulness of an energy spread beam.
ionsNarumi, Kazumasa; Naramoto, Hiroshi*; Yamada, Keisuke; Chiba, Atsuya; Saito, Yuichi; Morita, Yosuke*; Nakajima, Kaoru*; Kimura, Kenji*; Maeda, Yoshihito
no journal, ,
We have investigated cluster effects on damage accumulation and sputtering yield in bombardment of a Si crystal with 10-540-keV C ions. Fluence dependence of the areal density of displaced Si atoms can be well described by assuming a cylindrical volume affected by single-C-ion bombardment, which means an ion-track-like picture in damage accumulation in Si bombarded with keV C ions. The energy dependence of the number of displaced Si atoms by single-C-ion bombardment, N
, is different from that of N
by monatomic-C-ion bombardment calculated with SRIM2008. The number ratio of displaced Si atoms per C atom N/(60
N) which demonstrates the magnitude of the nonlinear effect on damage in Si has shown that the effect is huge and has the maximum around 100 keV. The energy dependence of the ratio can be explained qualitatively by nuclear stopping powers and increase of internuclear distances between C atoms in Si. The sputtering yield has the maximum, ca. 600 per C ion, around 100 keV. Comparing with the monatomic-ion-induced sputtering yield predicted by the linear-cascade theory by Sigmund, nonlinear effect on sputtering yield has been found. It depends on the ion energy: It is more pronounced around the energy where the sputtering yield has the maximum and hardly observed at 10 keV. No n
dependence is found, where n is the number of atoms consisting of the projectile cluster.
and C IonsNarumi, Kazumasa; Takahashi, Yasuyuki*; Chiba, Atsuya; Saito, Yuichi; Yamada, Keisuke; Ishikawa, Norito; Sugai, Hiroyuki*; Maeda, Yoshihito
no journal, ,
62.5-300-keV/u H and C ions were incident on self-supporting amorphous carbon foils of 2-100 
g/cm thickness, which was tilted by 45
to the beam axis. Secondary eletrons (SE) emitted in the forward and backward directions from a carbon foil were detected by two microchannel-plate (MCP) detectors placed at the both sides of the target holder in parallel with the target. Particles transmitted through the foil were detected with a solid-state detector placed at the backside of the target on the beam axis, which made it possible to measure the energy and the number of the transmitted particles. The forward and backward SE yields per incident projectile 
were determined from the pulse-height distributions of the forward and backward MCP signals, respectively, which are proportional to the number of detected SE's. The vicinage effect was evaluated with the ratios of the forward and backward SE yields R = (2)/2(1), where (2) and (1) are SE yields induced by bombardment with diatomic and monatomic ions with the same velocity, respectively. The origin of the vicinage effect on the SE yield will be discussed based on the observed foil-thickness and velocity dependence of the vicinage effect.
Kawaguchi, Kazuhiro; Takahiro, Katsumi*; Yamamoto, Shunya; Yoshikawa, Masahito; Nagata, Shinji*
no journal, ,
Optical absorption due to localized surface plasmon resonance (LSPR) of Au nanoparticles (Au NPs) is being applied to optical chemical sensors. In this work, ion sputtering and plasma cleaning have been employed to control the LSPR absorption. Au NPs on quartz and Si substrates were fabricated by RF magnetron sputtering method. The samples were characterized by UV-Vis extinction spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS). The peak position of LSPR absorption was shifted toward shorter wavelength after ion irradiation and plasma treatment. The SEM observation revealed that the average size of Au NPs did not change before and after ion irradiation and plasma treatment. The XPS analysis showed that the blue-shift of LSPR absorption was resulted from the elimination of hydrocarbons adhered on particle surfaces. We concluded that plasma and ion sputtering treatments are effective method to obtain Au NPs with clean surfaces.
Yamaki, Tetsuya; Nuryanthi, N.*; Koshikawa, Hiroshi; Asano, Masaharu; Sawada, Shinichi; Maekawa, Yasunari; Voss, K.-O.*; Trautmann, C.*; Neumann, R.*
no journal, ,
Ion-track membranes of poly(vinylidene fluoride) (PVDF), a type of fluoropolymer, have been used for many applications due to its superior chemical and mechanical properties. In order to produce track-etched pores in PVDF films, a highly-concentrated alkaline solution with an oxidizing agent has mostly been used at a high temperature, yet this provides irreversible chemical damage over the entire film including the non-irradiated part. We have independently employed much milder etching conditions without any oxidant additives in the alkaline etching solution. Because of the resulting negligibly-slow bulk etching, the finally-reaching plateau pore diameter could depend solely on the dose (or damage) distribution in each track. Therefore, we investigated here the effect of the track structure on etching behavior using different bombarding ions, and our finding on LET-sensitive track etching was applied to size and shape control of the obtained pores.
Yamaki, Tetsuya; Kato, Sho*; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
We prepared nanoparticles of tungsten (W) carbides by W-ion implantation in an unpolished glassy carbon (GC) substrate and then examined, for the first time, their composition, electrochemical properties, and morphology. The W implantation was performed at room temperature using an energy of 100 keV and nominal fluences of up to 1.810
ions/cm. Due to a significant sputtering effect and chemical interation between the implants and substrate, mostly W carbides, a mixture of WC and WC phases, were formed on the surface. The subsequent electrochemical etching in an alkaline solution achieved the smooth surface with maximum area density of the carbide phases. Particulate aggregates were found to contain spherical nanoparticles with a diameter of 
10 nm.
