Absorption spectrum of BkCl3

Abstract

The absorption spectrum of thin films of BkCl₃ was measured in the region $\text{∞\hspace{0.17em}3800–48\hspace{0.17em}000\hspace{0.17em}}{\mathrm{cm}}^{\text{−1}}$ at 298°, 77°, and 4°K. The absence of transitions from the ground state to excited J=0 and J=1 states, together with the number of crystal field components observed in several isolated groups, suggested that the ground level BkCl₃ is characterized by the crystal quantum number μ=0, as is the case in LaCl₃:Tb³⁺. Assignments were made based in part on a predicted energy level scheme which assumed a systematic variation in energy level parameters over the actinide series. The free‐ion electrostatic, spin orbit, and configuration interaction parameters for Bk³⁺ were calculated by a least squares fitting process involving 23 level assignments.