Theoretical and experimental study of the vibrational frequencies of UO and NpO in highly concentrated chloride solutions

Fujii, Toshiyuki*; Uehara, Akihiro*; Kitatsuji, Yoshihiro  ; Yamana, Hajimu*

The symmetric vibrational frequency of UO in chloride solutions was studied by Raman spectrometry and ab initio calculations. The frequency experimentally obtained decreased with the increase of concentration of Cl in solvent chlorides. This is attributable to that hydration water molecules in the equatorial plane of UO are substituted by Cl ions, which was consistent with the calculation results. The theoretical part was expanded to aqua- and chloro- Np(VI) complexes. The frequencies of neptunyl species computed were acceptable compared with the reported Raman shifts.