Fluorescence and excitation spectra of Bk3+, Cf3+, and Es3+ ions in single crystals of LaCl3

Dye laser techniques have been used to study the energy level structure of the heavier actinides in single crystals of lanthanum chloride. In the case of einsteinium, fluorescence was detected and measured from the following manifolds: J = 5 at 0.984 μm-1, J = 4 at 1.572 μm-1, J = 6 at 2.930 μm-1. This fluorescence was observed to the five lowest manifolds: J = 8, 5, 7, 2, 6. For californium, fluorescence has been detected from the manifolds: J = 11/2 at 1.190 μm-1, J = 7/2 at 1.389 μm-1, J = 5/2 at 1.977 μm-1. This fluorescence was observed to the three lowest manifolds: J = 15/2, 9/2, 11/2. The fluorescence manifolds of berkelium are J = 6 at 1.540 μm-1, and J = 4 at 1.953 μm-1. The three lowest manifolds, J = 6, 5, and 4, have been observed in fluorescence. Absorption spectra data have yielded crystal-field splitting measurements in the higher manifolds of Es+. The location of the manifolds in general confirmed earlier approximate free-ion level structure calculations based on assumed regularities in the energy level parameters derived from spectra of the actinide ions through Cf+. 2 figures