Raman Spectroscopic Study on NpO 2 + –ca 2+ Interaction in Highly Concentrated Calcium Chloride

Coordination circumstance of neptunyl ion in concentrated CaCl 2 solutions was analyzed by Raman spectrometry. Besides the symmetric stretch (ν 1 ) mode of NpO 2 + and NpO 2 2+ , the asymmetric stretch (ν 3 ) mode of NpO 2 + was found. The Raman intensity of the ν 3 mode increased with the concentration of CaCl 2 in the system. This would be attributable to the cation–cation interaction between Np(V) and Ca(II).