MECHANISMS OF PHOTOCHEMICAL-REACTIONS OF NEPTUNIUM IONS IN PERCHLORIC-ACID SOLUTIONS

Photochemical reactions of Np(V) and NB(VI) in 0.001-1.0 M HClO4 solut ions were studied. Both oxidation of Np(V) and reduction of Np(VI) occ ur under UV irradiation of such solutions, the efficiency of the first reaction increasing, and that of the second reaction decreasing with increasing acid concentration. Possible mechanisms of reactions were d iscussed. The probabilities of various reactions were calculated. It w as shown that the mechanisms proposed in the literature do not agree w ith the experiment. The photochemical reactions of neptunium are prove d to involve formation of excimers - dimers consisted of excited and u nexcited neptunium ions.