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Journal Articles

Atomic position and the chemical state of an active Sn dopant for Sn-doped $$beta$$-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

 Times Cited Count:0

Journal Articles

Selective adsorption of Pd(II) over Ag(I) in nitric acid solutions using nitrogen-donor-type adsorbents

Suzuki, Tomoya*; Otsubo, Ukyo*; Ogata, Takeshi*; Shiwaku, Hideaki; Kobayashi, Toru; Yaita, Tsuyoshi; Matsuoka, Mitsuaki*; Murayama, Norihiro*; Narita, Hirokazu*

Separation and Purification Technology, 308, p.122943_1 - 122943_7, 2023/03

 Times Cited Count:2 Percentile:22.61(Engineering, Chemical)

HNO$$_{3}$$ leaching is used in recycling Pd metal from spent products that primarily contain Ag, and most Pd residues are separated from solutions containing Ag(I). However, a small amount of Pd(II) often remains in these Ag(I) solutions. Therefore, the separation of Pd(II) and Ag(I) in HNO$$_{3}$$ solutions is essential to promote efficient Pd recycling. In this study, the separation of Pd(II) and Ag(I) in HNO$$_{3}$$ solutions was investigated using four N-donor-type adsorbents functionalized with amine (R-Amine), iminodiacetic acid (R-IDA), pyridine (R-Py), or bis-picolylamine (R-BPA). R-Amine, R-IDA, and R-Py selectively adsorbed Pd(II) over Ag(I), Cu(II), Ni(II), and Fe(III) from HNO$$_{3}$$ solutions (0.3-7 M), but R-Amine exhibited a lower Pd adsorption efficiency. In contrast, $$>$$90% of Pd(II), Ag(I), and Cu(II) were adsorbed by R-BPA over the entire range of HNO$$_{3}$$ concentrations. Structural analyses of the adsorbed metal ions using Fourier transform infrared spectroscopy and extended X-ray absorption fine structure spectroscopy revealed the separation mechanisms of the N-donor-type adsorbents. Pd(II) adsorption on R-IDA, R-Py, and R-BPA occurred via Pd(II) coordination of the functional groups (iminodiacetic acid, pyridine, and bis-picolylamine, respectively), whereas that on R-Amine occurred via anion exchange of NO$$_{3}$$$$^{-}$$ with [Pd(NO$$_{3}$$)$$_{4}$$]$$^{2-}$$. The coordinative adsorption mechanisms resulted in the higher Pd(II) adsorption behaviors of R-IDA, R-Py, and R-BPA. HCl (5.0 M) and thiourea (0.1 M) eluents desorbed 83% of Pd(II) from R-IDA and 95% from R-Py, respectively. R-Py was the most effective Pd(II) adsorbent based on adsorption selectivity and desorption efficiency.

Journal Articles

Study on the relation between the crystal structure and thermal stability of FeUO$$_{4}$$ and CrUO$$_{4}$$

Akiyama, Daisuke*; Kusaka, Ryoji; Kumagai, Yuta; Nakada, Masami; Watanabe, Masayuki; Okamoto, Yoshihiro; Nagai, Takayuki; Sato, Nobuaki*; Kirishima, Akira*

Journal of Nuclear Materials, 568, p.153847_1 - 153847_10, 2022/09

 Times Cited Count:3 Percentile:66.21(Materials Science, Multidisciplinary)

FeUO$$_{4}$$, CrUO$$_{4}$$, and Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ are monouranates containing pentavalent U. Even though these compounds have similar crystal structures, their formation conditions and thermal stability are significantly different. To determine the factors causing the difference in thermal stability between FeUO$$_{4}$$ and CrUO$$_{4}$$, their crystal structures were evaluated in detail. A Raman band was observed at 700 cm$$^{-1}$$ in all the samples. This Raman band was derived from the stretching vibration of the O-U-O axis band, indicating that Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ was composed of a uranyl-like structure in its lattice regardless of its "x"' value. M$"o$ssbauer measurements indicated that the Fe in FeUO$$_{4}$$ and Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ were trivalent. Furthermore, Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ lost its symmetry around Fe$$^{mathrm{III}}$$ with increasing electron densities around Fe$$^{mathrm{III}}$$, as the abundance of Cr increased. These results suggested no significant structural differences between FeUO$$_{4}$$ and CrUO$$_{4}$$. Thermogravimetric measurements for UO$$_{2}$$, FeUO$$_{4}$$, and CrUO$$_{4}$$ showed that the temperature at which FeUO$$_{4}$$ decomposed under an oxidizing condition (approximately 800 $$^{circ}$$C) was significantly lower than the temperature at which the decomposition of CrUO$$_{4}$$ started (approximately 1250 $$^{circ}$$C). Based on these results, we concluded that the decomposition of FeUO$$_{4}$$ was triggered by an "in-crystal" redox reaction, i.e., Fe$$^{mathrm{III}}$$ $${+}$$ U$$^{mathrm{V}}$$ $$rightarrow$$ Fe$$^{mathrm{II}}$$ $${+}$$ U$$^{mathrm{VI}}$$, which would not occur in the CrUO$$_{4}$$ lattice because Cr$$^{mathrm{III}}$$ could never be reduced under the investigated condition. Finally, the existence of Cr$$^{mathrm{III}}$$ in FexCr$$_{1-x}$$UO$$_{4}$$ effectively suppressed the decomposition of the Fe$$_{x}$$Cr$$_{1-x}$$UO$$_{4}$$ crystal, even at a very low Cr content.

Journal Articles

Spectroscopic measurements of L X-rays with a TES microcalorimeter for a non-destructive assay of transuranium elements

Nakamura, Keisuke; Morishita, Yuki; Takasaki, Koji; Maehata, Keisuke*; Sugimoto, Tetsuya*; Kiguchi, Yu*; Iyomoto, Naoko*; Mitsuda, Kazuhisa*

Journal of Low Temperature Physics, 193(3-4), p.314 - 320, 2018/11

 Times Cited Count:0 Percentile:0(Physics, Applied)

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

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$$_{3/2}$$ $$rightarrow$$ 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

Electronic structures of ferromagnetic CeAgSb$$_{2}$$; Soft X-ray absorption, magnetic circular dichroism, and angle-resolved photoemission spectroscopies

Saito, Yuji; Fujiwara, Hidenori*; Yamaguchi, Takashi*; Nakatani, Yasuhiro*; Mori, Takeo*; Fuchimoto, Hiroto*; Kiss, Takayuki*; Yasui, Akira*; Miyawaki, Jun*; Imada, Shin*; et al.

Journal of the Physical Society of Japan, 85(11), p.114713_1 - 114713_7, 2016/11

 Times Cited Count:15 Percentile:67.86(Physics, Multidisciplinary)

We report on the electronic structures of ferromagnetic CeAgSb$$_{2}$$ using soft X-ray absorption (XAS), magnetic circular dichroism (XMCD), and angle-resolved photoemission (ARPES) spectroscopies. The Ce $$M_{4,5}$$ XAS spectra show very small satellite structures, reflecting a strongly localized character of the Ce 4${it f}$ electrons. The linear dichroism effects in the Ce $$M_{4,5}$$ XAS spectra demonstrate the ground-state Ce 4${it f}$ symmetry of $$Gamma$$$$_{6}$$, the spatial distribution of which is directed along the ${it c}$-axis. Nevertheless, ARPES spectra at the Ce 3$$d$$-4$$f$$ resonance show the momentum dependence of the intensity ratio between Ce 4$$f^{1}_{5/2}$$ and 4$$f^{1}_{7/2}$$ peaks in a part of the Brillouin zone, suggesting the non negligible momentum-dependent hybridization effect between the Ce 4${it f}$ and the conduction electrons. This is associated with the moderate mass enhancement in CeAgSb$$_{2}$$.

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

 Times Cited Count:2 Percentile:19.57(Nuclear Science & Technology)

Journal Articles

Tungsten impurity density in fusion plasma

Nakano, Tomohide; Shumack, A.*; Maggi, C. F.*

Journal of Physics B; Atomic, Molecular and Optical Physics, 2 Pages, 2016/01

Collaboration of researchers from Japan Atomic Energy Agency and EUROfusion Consortium (Dutch Institute For Fundamental Energy Research, Max-Planck-Institut f$"{u}$r Plasmaphysik and so on) successfully led to determination of tungsten ion density in high temperature plasmas in Joint European Torus (JET) with an upgraded X-ray spectrometer. The researchers used the FAC code and successfully identified $$mbox{W}^{45+}$$, $$mbox{W}^{46+}$$ and $$mbox{Mo}^{32+}$$ spectral lines. The $$mbox{Mo}^{32+}$$ line identification was confirmed experimentally by Mo injection to the plasma. From the measured absolute intensity of these spectral lines, tungsten and molybdenum ion densities in the plasma core were determined.

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

 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

Polymerization of C$$_{60}$$ thin films by ion irradiation

Narumi, Kazumasa; Sakai, Seiji; Naramoto, Hiroshi*; Takanashi, Koki

JAEA-Review 2005-001, TIARA Annual Report 2004, p.238 - 240, 2006/01

no abstracts in English

Journal Articles

Characterization of C$$_{60}$$ films polymerized by ion irradiation

Narumi, Kazumasa; Sakai, Seiji; Naramoto, Hiroshi*; Takanashi, Koki

Fullerenes, Nanotubes, and Carbon Nanostructures, 14(2-3), p.429 - 434, 2006/00

no abstracts in English

Journal Articles

Fundamental and harmonic emission from the rear side of a thin overdense foil irradiated by an intense ultrashort laser pulse

Eidmann, K.*; Kawachi, Tetsuya; Marcinkevicius, A.*; Bartlome, R.*; Tsakiris, G.*; Witte, K.*; Teubner, U.*

Physical Review E, 72(3), p.036413_1 - 036413_9, 2005/09

 Times Cited Count:33 Percentile:77.25(Physics, Fluids & Plasmas)

In order to clarify the mechanism of high-order harmonics generation from solid target, we investigated the emission from rear side of the foil target irradiated by an intense Ti:S laser pulse, duration of 150 fs. The comparison of the exprimental result with our Particle-in-Cell simulation implies that rear side emission is caused by energetic electron bunches which is generated at the front side by resonance absorption.

Journal Articles

Recent progress in X-ray laser research in JAERI

Kawachi, Tetsuya; Nagashima, Keisuke; Kishimoto, Maki; Hasegawa, Noboru; Tanaka, Momoko; Ochi, Yoshihiro; Nishikino, Masaharu; Kawazome, Hayato; Tai, R.; Namikawa, Kazumichi*; et al.

Proceedings of SPIE's International Symposium on Optics and Photonics 2005, Vol.5919, p.59190L_1 - 59190L_11, 2005/09

Recent results of the X-ray laser research in Advanced Photon Research (APR) Center in JAERI are reported. In the application of the nickel-like silver laser at a wavelength of 13.9 nm, we report the observation of the microscopic polarization clusters in ferroelectrics material such as BaTi03 by use of the X-ray speckle technique, and other experiments such as photo-ionization of inner-shell electrons are intoroduced. In the development of high quality X-ray laser beam, recently we demonstrated temporally coherent X-ray beam at 23.6 nm, in which the high-order harmonics light was injected into the Ne-like Mn X-ray amplifier. We also mention about the development of new X-ray laser driver laser, which is based on 2 beams of zig-zag slab Nd:glass lasers with 0.1 Hz repetition-rate, and each beam line can provide 10 J output energy, and 1 ps duration.

Journal Articles

Resonant O K$$alpha$$ emission spectroscopy of layered manganate La$$_{1.2}$$Sr$$_{1.8}$$Mn$$_{2}$$O$$_{7}$$

Agui, Akane; K$"a$$"a$mbre, T.*; S${aa}$the, C.*; Nordgren, J.*; Usuda, Manabu; Saito, Tomohiko*; Moritomo, Yutaka*

Journal of Electron Spectroscopy and Related Phenomena, 144-147, p.589 - 592, 2005/06

 Times Cited Count:1 Percentile:5.68(Spectroscopy)

Current research in the perovskite and layered perovskite-type manganese oxides has expanded to include the study of electronic and magnetic properties such as the colossal magnetoresistance (CMR), orbital ordering and charge ordering. The O K$$alpha$$ soft X-ray emission and absorption spectra (XES and XAS) of La$$_{1.2}$$Sr$$_{1.8}$$Mn$$_{2}$$O$$_{7}$$ were measured at selected excitation energies in order to investigate the electronic structure. The measurements were carried out by using a soft X-ray emission spectrometer at beamline BW3 at HASYLAB, Germany. The dependence of O K$$alpha$$ XES on excitation-energy was observed. It is attributed the different site of oxygen ions.

Journal Articles

Synchrotron radiation photoabsorption and photoemission spectroscopy for thermal-induced reoriented Si polymer

Nath, K. G.; Shimoyama, Iwao; Sekiguchi, Tetsuhiro; Baba, Yuji

Journal of Electron Spectroscopy and Related Phenomena, 144-147, p.323 - 326, 2005/06

 Times Cited Count:5 Percentile:27.33(Spectroscopy)

The effect of laser annealing on electronic atructures and molecular orientation for poly(dimethylsilane), {PDMS, [Si(CH$$_{3}$$)$$_{2}$$]$$_{n}$$} has been studied by synchrotron radiation photoemission and photoabsorption spectroscopy. Prior to annealing, PDMS powder was mounted on the basal plane of highly oriented pyrolytic graphite. Both Si 1s X-ray photoemission spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at Si 1s edge show that electronic structures have been modified due to annealing. Furthermore, the angle-dependent NEXAFS spectra clearly indicate that the annealed products maintain a specific orientation. Interestingly, no such kind of orientation is present in as-received PDMS powder as no angle-dependency is observed before annealing.

Journal Articles

Ultrafast X-ray absorption spectroscopy of laser-excited materials

Koike, Masato

JAERI-Conf 2005-004, p.15 - 18, 2005/04

Advanced Light Source (ALS) Beamline 6.0 is designed for X-ray absorption spectroscopy with femtosecond X-ray pulses generated by the bunch "slicing" technique. Soft and hard X-ray branch lines will cover a wide photon energy range from 120 eV to 10 keV. A soft X-ray spectrograph will collect absorption spectra dispersively. The application of laminar gratings to dispersive X-ray absorption spectroscopy in the photon energy range 2- 8 keV has been investigated.

Journal Articles

O 2$$p$$ hole-assisted electronic processes in the Pr$$_{1-x}$$Sr$$_{x}$$MnO$$_{3}$$ (x=0.0, 0.3) system

Ibrahim, K.*; Qian, H. J.*; Wu, X.*; Abbas, M. I.*; Wang, J. O.*; Hong, C. H.*; Su, R.*; Zhong, J.*; Dong, Y. H.*; Wu, Z. Y.*; et al.

Physical Review B, 70(22), p.224433_1 - 224433_9, 2004/12

 Times Cited Count:30 Percentile:75.04(Materials Science, Multidisciplinary)

no abstracts in English

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

 Times Cited Count:13 Percentile:61.44(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

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($$phi$$=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.

Journal Articles

Development of scanning-type synchrotron radiation m$"o$ssbauer microscope using focused X-ray

Mitsui, Takaya; Kobayashi, Yasuhiro*; Seto, Makoto

Japanese Journal of Applied Physics, Part 1, 43(1), p.389 - 393, 2004/01

 Times Cited Count:11 Percentile:42.73(Physics, Applied)

A scanning-type synchrotron radiation Mossbauer microscope was designed and installed at the nuclear resonance beamline BL11XU of the SPring-8 facility. The focused Mossbauer probe beam ($$Phi$$$$sim$$20$$mu$$m) is obtained by the combination of a high-resolution monochromator, a multilayer X-ray focusing mirror and a pinhole slit. Using this Mossbauer microscope, we have performed, for the first time,the synchrotron radiation Mossbauer microscopic measurements of nuclear resonant forward scattering from an iron borate single crystal as a function of the sample position. It was found that the observed Mossbauer time spectra depend on the direction of the local hyper fine magnetic field and the local specimen thickness.

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