Spectroscopic and redox properties of berkelium in complexing aqueous carbonate and citrate solutions

Multimilligram quantities of berkelium-249 were investigated by UV-VIS-NIR absorption spectroscopy and bulk solution electrolysis in concentrated aqueous carbonate and citrate solutions at ambient temperature. Berkelium concentrations between 10-2 and 10-3 M were used in 0.5, 2, and 5 M carbonate solutions at pH values between 10.0 and 13.5 and in 0.1 M citrate solutions between pH1 and 4. Presented here are the first reported absorption spectra of Bk(III) in both carbonate and citrate media. Since Bk(III) is quite unstable to oxidation in basic carbonate solutions, it was necessary to reduce the stable Bk(IV)-carbonate solution at a mercury pool cathode. This was performed in a specially designed coaxial electrolysis cell which is described in this report. The spectra of Bk(IV) in 2 and 5 M carbonate were recorded and compared to literature spectra. All of the spectra are compared to those of berkelium in noncomplexing perchloric acid. A new, solid, hydroxy-carbonato-Bk(IV) complex has been prepared and partially characterized. (orig.)