Chemical studies of rutherfordium (Rf) and nobelium (No) on an atom-at-a-time scale

シングルアトムレベルでのラザホージウムとノーベリウムの化学的研究

豊嶋 厚史

Toyoshima, Atsushi

近年、原子力機構で行われたラザホージウム(Rf)並びにノーベリウム(No)の化学的研究について概説する。迅速化学分離装置を用いてHF/HNO水溶液中におけるRfの陰イオン交換挙動を同族元素Zr並びにHfとともに調べた。実験条件下において、RfがZrやHfと同様にヘキサフルオロ錯体を形成する一方で、Rfの錯形成定数がZr, Hfに比べて少なくとも一桁以上小さいことを明らかにした。また、新たに開発した電解カラムクロマトグラフ装置を用いて、-ヒドロキシイソ酪酸水溶液中におけるNoの酸化実験を行った。その結果、シングルアトムレベルでNoに酸化することに初めて成功した。

Chemical studies of rutherfordium (Rf) and nobelium (No) recently carried out at JAEA are reviewed. Anion-exchange behavior of Rf in HF and HNO mixed solution was studied together with short-lived Zr and Hf isotopes using an automated chemistry apparatus. It was found that the hexafluoro complex of Rf is present in the solutions under the given conditions where the same complexes of Zr and Hf are existing. The formation constant of the Rf complex was evaluated to be at least one order of magnitude smaller than those of Zr and Hf. Oxidation experiments of No was conducted in 0.1 M -hydroxyisobutyric (-HIB) acid using a newly developed electrolytic column chromatography apparatus on an atom-at-a-time scale. The result clearly demonstrated that stable No is successfully oxidized to the trivalent state, No, which is held in the -HIB solution.