Electrochemical preparation and spectroelectrochemical study of neptunium chloride complexes in LiCl-KCl eutectic melts

We prepared neptunium chloride complexes electrochemically and performed spectroelectrochemical measurements of neptunium ions in LiCl-KCl eutectic melts at 450 A degrees C, where the neptunium concentrations studied were in the range of 0.1-1 mM. We observed a highly absorbing f-d transition band of Np3+ at 383 nm, which was used to determine an formal potential of the Np4+|Np3+ redox couple (EA degrees' = 0.45 V vs. Ag|Ag+) with a solution of concentration as low as similar to 0.1 mM. This result agreed well with the value (EA degrees' = 0.42 V vs. Ag|Ag+) determined by cyclic voltammetry with a similar to 15 mM solution.