Emission profile of Bk(III) in a silicate matrix: Anomalous dependence on excitation power

We have been conducting spectroscopic investigations of the transuranium elements in silicate glasses. These studies included spectroscopic monitoring of the decay profiles of selected short-lived actinides. Although the latter are not candidates for immobilization hosts, their half-lives make them attractive for probing certain fundamental issues. One facet of these studies has been spectroscopic investigations of Bk in a silicate matrix. Optical spectroscopy has shown that the trivalent state of Bk is the stable state in this matrix, and Bk(III) exhibits primarily two emission bands, centered at 15 340 and 13 475 cm-1. The relative intensities of these two bands exhibit an unusual dependence on excitation power. At low power levels, the 13 475 cm-1 emission dominates; with increased power levels, the emission intensity of the 13 475 cm-1 band decreases at a greater rate than the band at 15 340 cm-1. As a result, this latter band dominates at higher excitation powers. A similar dependence of these two Bk(III) emission bands with temperature has also been noted. Details of the emission profile of Bk in this matrix and the basis for the observed power dependence are discussed. © 1998 Elsevier Science S.A.