ANALYSIS OF ABSORPTION AND LUMINESCENCE SPECTRA OF U3-CRYSTALS( DOPEDCS2NAYCL6 AND CS2LIYCL6 SINGLE)

Uranium(3+) doped single crystals of Cs2NaYCl6 and Cs2LiYCl6 with a 2. 0% and 0.1% U3+ concentration have been obtained by the Bridgman-Stock barger method. Luminescence spectra of the crystals were recorded at 1 60, 70, and 15 K. The emission bands observed in the visible and near infrared regions have been assigned to transitions from the lowest com ponents of the I-4(11/2), F-4(3/2), and (4)G(7/2) multiplets to the cr ystal-field components of the I-4(9/2) ground level. Absorption spectr a were recorded from 4 000 to 25 000 cm(-1) at 4.2 K. The zero phonon transitions were identified from an analysis of the vibronic side band s as well as in least-squares fits by applying a semiempirical Hamilto nian representing the combined atomic and crystal-field interactions f or an ion of-the 5f(3) configuration and O-h symmetry. Eight energy le vel parameters were varied simultaneously in the least-squares adjustm ents yielding a mean error of 57 and 61 cm(-1) for U3+:Cs2LiYCl6 and U 3+:Cs2NaYCl6, respectively. The analysis of the spectra enabled the as signment of 25 crystal field levels for U3+:Cs2NaYCl6 and 27 for U3+:C s2LiYCl6. The received total splitting of the ground level is equal to 625 and 595 cm(-1), respectively. (C) 1998 American Institute of Phys ics.