SPECTROSCOPIC STUDIES AND CRYSTAL-FIELD ANALYSES OF AM3+LIYF4

Fluorescence and laser selective excitation spectroscopy have been use d to investigate the electronic energy level structure of the actinide Am3+ (5f(6)) in LiYF4. From the analysis of the fluorescence in the v isible and infrared spectra obtained at 10 K, 29 crystal-field levels have been assigned in the D-2d approximation. Zeeman splitting observa tion permits one to index some doubly degenerated Gamma(5) levels. The phenomenological crystal-field parameters have been calculated in the D-2d approximation. A least-square adjustment yields a mean error of 38 cm(-1) with the following values (in cm(-1)) of the B-q(k) paramete rs: B-0(2) = 473, B-0(4) = -1776, B-4(4) = -2253, B-0(6) = 80, and B-4 (6) = -2222. (C) 1997 Academic Press.