Characterization of heavy actinides with electrochemistry

Toyoshima, Atsushi; Kasamatsu, Yoshitaka; Tsukada, Kazuaki  ; Asai, Masato  ; Kitatsuji, Yoshihiro  ; Haba, Hiromitsu*; Ishii, Yasuo; Tome, Hayato; Nishinaka, Ichiro; Oe, Kazuhiro*; Sato, Wataru*; Shinohara, Atsushi*; Akiyama, Kazuhiko*; Nagame, Yuichiro 

We present a characterization technique for heavy actinides with electrochemistry. An electrochemistry apparatus combined with a chromatographic separation technique was developed to identify oxidation states of the heavy actinides on an atom-at-a-time scale. Oxidation states of nobelium (No) in aqueous solution were studied using the apparatus. Nobelium-255 with a half-life of 3.1 min was produced in the Cm(C, 5n) reaction at the JAEA tandem accelerator. Chromatographic behavior of No on a chemically modified electrode with Nafion perfluoronated ion-exchange resin was investigated in ammonium -hydroxyisobutyric acid solution. It has been found that No is bound in the most stable divalent state at low applied potentials while it exists as the trivalent ion at higher potentials, showing the electrochemical oxidation of No.