Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

https://doi.org/10.1038/s41550-020-01271-2

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Transmission secondary ion mass spectrometry using 5 MeV C ions

Nakajima, Kaoru*; Nagano, Kengo*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Hirata, Koichi*; Kimura, Kenji*

Applied Physics Letters, 104(11), p.114103_1 - 114103_4, 2014/03

https://doi.org/10.1063/1.4868655

Transmission properties of C ions through micro- and nano-capillaries

Tsuchida, Hidetsugu*; Majima, Takuya*; Tomita, Shigeo*; Sasa, Kimikazu*; Narumi, Kazumasa; Saito, Yuichi; Chiba, Atsuya; Yamada, Keisuke; Hirata, Koichi*; Shibata, Hiromi*; et al.

Nuclear Instruments and Methods in Physics Research B, 315, p.336 - 340, 2013/11

https://doi.org/10.1016/j.nimb.2013.04.094

Secondary ion emission from PTFE upon C ion impacts

Hirata, Koichi*; Saito, Yuichi; Chiba, Atsuya; Yamada, Keisuke; Takahashi, Yasuyuki*; Narumi, Kazumasa; Kamiya, Tomihiro

JAEA-Review 2011-043, JAEA Takasaki Annual Report 2010, P. 156, 2012/01

https://doi.org/10.11484/jaea-review-2011-043

Production and properties of transuranium elements

Nagame, Yuichiro; Hirata, Masaru

Radiochimica Acta, 99(7-8), p.377 - 393, 2011/08

https://doi.org/10.1524/ract.2011.1853

Production and chemistry of transuranium elements

Nagame, Yuichiro; Hirata, Masaru; Nakahara, Hiromichi*

Handbook of Nuclear Chemistry, p.817 - 875, 2011/02

https://doi.org/10.1007/978-1-4419-0720-2_18

Chloride complexation of Zr and Hf in HCl investigated by extended X-ray absorption fine structure spectroscopy; Toward characterization of chloride complexation of element 104, rutherfordium (Rf)

Haba, Hiromitsu*; Akiyama, Kazuhiko*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Yaita, Tsuyoshi; Hirata, Masaru; Sueki, Keisuke*; Nagame, Yuichiro

Bulletin of the Chemical Society of Japan, 82(6), p.698 - 703, 2009/06

https://doi.org/10.1246/bcsj.82.698

Chloride complexation of the group-4 elements Zr and Hf in 8.0-11.9 M HCl is investigated by Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy to characterize chloro complexes of the transactinide element, rutherfordium (Rf). The complexes of Zr and Hf successively vary with the concentration of HCl from a hydrated complex [M(HO) ] at 8.0 M to a hexachloro complex [MCl] at 11.9 M (M = Zr and Hf). The present structural changes of the Zr and Hf complexes well reflect the previously studied anion-exchange behavior of Zr and Hf in HCl. From both the EXAFS and anion-exchange results, we suggest that Rf forms the same complexes as those of Zr and Hf in HCl, and that the complexation strength of the hexachloro complexes of the group-4 elements, [MCl] (M = Zr, Hf, and Rf), is in the sequence of Rf Zr Hf.

Organic contaminant detection of silicon wafers using negative secondary ions induced by cluster ion impacts

Hirata, Koichi*; Saito, Yuichi; Chiba, Atsuya; Narumi, Kazumasa

Applied Physics Express, 1(4), p.047002_1 - 047002_3, 2008/04

https://doi.org/10.1143/APEX.1.047002

Fluoride complexation of element 104, rutherfordium

Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Nishinaka, Ichiro; Hirata, Masaru; Yaita, Tsuyoshi; Ichikawa, Shinichi; Nagame, Yuichiro; et al.

Journal of the American Chemical Society, 126(16), p.5219 - 5224, 2004/04

https://doi.org/10.1021/ja031824u

Fluoride complexation of element 104, rutherfordium (Rf), produced in the Cm(O,5n)Rf reaction has been studied by anion-exchange chromatography on an atom-at-a-time scale. The anion-exchangechromatographic behavior of Rf was investigated in 1.9-13.9 M hydrofluoric acid together with those of the group-4 elements Zr and Hf produced in the O-induced reactions on Ge and Gd targets, respectively. It was found that the adsorption behavior of Rf on anion-exchange resin is quite different from those of Zr and Hf, suggesting the influence of relativistic effect on the fluoride complexation of Rf.

Transactinide nuclear chemistry at JAERI

Nagame, Yuichiro; Haba, Hiromitsu; Tsukada, Kazuaki; Asai, Masato; Akiyama, Kazuhiko; Hirata, Masaru; Nishinaka, Ichiro; Ichikawa, Shinichi; Nakahara, Hiromichi; Goto, Shinichi*; et al.

Czechoslovak Journal of Physics, 53, p.A299 - A304, 2003/00

https://doi.org/10.1007/s10582-003-0038-3

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