Mössbauer effect studies on some heptavalent neptunium compounds

Abstract

Four heptavalent neptunium compounds, Li₅NpO₆, [Co(en)₃]NpO₅,xH₂O, Ba₃(NpO₅)₂,xH₂O, and Ca₃(NpO₅)₂,-xH₂O have been studied by Mössbauer spectroscopy. The measured isomer shifts of ²³⁷Np in these compounds confirm the heptavalent oxidation state of neptunium. Bond properties are inferred from the isomer-shift values on the basis of valence-bond theory. Structural properties of the neptunate(VII) anions are derived from the observed data for the quadrupole splitting and asymmetry parameter.