JOPSS - Search Results

Journal Articles

Atomic position and the chemical state of an active Sn dopant for Sn-doped -Ga $_{2}$ O $_{3}$ (001)

Tsai, Y. H.*; Kobata, Masaaki; Fukuda, Tatsuo; Tanida, Hajime; Kobayashi, Toru; Yamashita, Yoshiyuki*

Applied Physics Letters, 124(11), p.112105_1 - 112105_5, 2024/03

https://doi.org/10.1063/5.0198160

Journal Articles

Chemical states of trace-level strontium adsorbed on layered oxide by XPS and XANES under total reflection condition

Baba, Yuji; Shimoyama, Iwao

Photon Factory Activity Report 2016, 2 Pages, 2017/00

http://pfwww.kek.jp/acr/2016pdf/u_reports/pf16b0047.pdf

In order to elucidate the adsorption states of radioactive Sr-90 in soil, chemical bonding states of non-radioactive strontium adsorbed on layered oxide (mica) have been investigated by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) spectroscopy. Since the number of atoms in radioactive Sr-90 is extremely small, the XPS and XANES were measured under total reflection condition of the incident X-rays. The detection limit in total reflection XPS was about 150 pg/cm $^{2}$ , which corresponds to 300 Bq of Sr-90. The Sr 2p $_{3/2}$ core-level energy in XPS shifted to lower energy with the decrease in the thickness of Sr layer. Also, the Sr 2p $_{3/2}$ Sr 4d $^{*}$ resonance energy in XANES shifts to lower energy with the decrease in the thickness. On the basis of a simple point charge model, it was elucidated that the chemical bond between Sr and mica surface becomes ionic with the decrease in the adsorbed amount of strontium.

Journal Articles

Hard X-ray photoelectron spectroscopy study for transport behavior of CsI in heating test simulating a BWR severe accident condition; Chemical effects of boron vapors

Okane, Tetsuo; Kobata, Masaaki; Sato, Isamu*; Kobayashi, Keisuke*; Osaka, Masahiko; Yamagami, Hiroshi

Nuclear Engineering and Design, 297, p.251 - 256, 2016/02

https://doi.org/10.1016/j.nucengdes.2015.10.029

Times Cited Count：2 Percentile：19.71(Nuclear Science & Technology)

Journal Articles

Interaction between ultra-trace amount of cesium and oxides studied by total-reflection X-ray photoelectron spectroscopy

Baba, Yuji; Shimoyama, Iwao; Hirao, Norie; Izumi, Toshinori

e-Journal of Surface Science and Nanotechnology (Internet), 13, p.417 - 421, 2015/09

https://doi.org/10.1380/ejssnt.2015.417

Times Cited Count：1

The interaction between alkali metals and oxides has attracted much attention as heterogeneous catalysis, chemical reaction promoters, and high intensity electron emitter. Also the interaction of cesium and oxides has become important subject, because radioactive cesium trapped in minerals such as clay and soil may cause health risks. In the present study, we analyzed chemical states of ultra-trace amount of cesium on oxide surfaces by total reflection X-ray photoelectron spectroscopy (TR-XPS) exited by synchrotron radiation. For the adsorbed cesium thicker than 0.01 layer, cesium is weakly bound with oxide through Van-der-Waals force. On the other hand, for ultra-thin layer about 0.002 layer, the chemical bond changes to covalent bond. It is suggested that this change in the chemical bonding state is one of the reasons why radioactive cesium is hard to be released from minerals.

Journal Articles

New laser decontamination technique for radioactively contaminated metal surfaces using acid-bearing sodium silicate gel

Kameo, Yutaka; Nakashima, Mikio; Hirabayashi, Takakuni*

Journal of Nuclear Science and Technology, 41(9), p.919 - 924, 2004/09

https://doi.org/10.3327/jnst.41.919

Times Cited Count：12 Percentile：61.53(Nuclear Science & Technology)

A new laser decontamination method utilizing a gel made from a sodium silicate solution and an acid was developed for removing radioactive nuclide incorporated into a surface oxide layer on metal waste. Decontamination tests were carried out using both simulated contaminated samples and pipe specimens cut from the primary coolant system of the Japan Power Demonstration Reactor. In the case of surface oxide layer consisting mainly of iron oxide, more than 99% of surface radioactivities were removed after two to three decontamination runs. In order to ascertain the role of laser irradiation on chemical reactions, chemical states of O and Fe in the oxide layer before and after decontamination were analyzed by X-ray photoelectron spectroscopy. It was found that the oxide layer was dissolved into the acid-containing gel, and the reaction was extensively promoted by the laser irradiation.

Journal Articles

Energetic deuterium and helium irradiation effects on chemical structure of CVD diamond

Sasaki, Masayoshi*; Morimoto, Yasutomi*; Kimura, Hiromi*; Takahashi, Koji; Sakamoto, Keishi; Imai, Tsuyoshi; Okuno, Kenji*

Journal of Nuclear Materials, 329-333(Part1), p.899 - 903, 2004/08

https://doi.org/10.1016/j.jnucmat.2004.04.275

A CVD diamond has been the reference material of a torus widow for a rf heating system in a fusion reactor. Since the window is in the circumstance of tritium, helium and radio activated dust, it is important to elucidate the effect of ions on chemical structure of the diamond, existing states of tritium and tritium inventory. Polycrystalline CVD diamond disks(=10.0mm, t=0.21mm) used in this study are the same grade as rf windows. After sputtering the surface with 1.0 keV Ar $^{+}$ to remove oxygen impurity, the sample was irradiated with deuterium (D $_{2}$ $^{+}$ ) or helium ions (He $^{+}$ ) at an angle of 0 degrees to the surface normal. The irradiation energies of deuterium and helium are 0.25 keV D $^{+}$ and 0.45 keV He $^{+}$ , respectively. The structural change of the irradiated sample was measured by X-ray Photoelectron Spectroscopy (XPS) technique. The C1s peak shift toward lower binding energy side was observed when deuterium ions irradiated. This result indicates that the diamond changes to amorphous carbon due to formation of C-D bond.