Effects of self-radiation damage on electronic properties of 244Cm 3+ in an orthophosphate crystal of YPO 4

Abstract

The electronic energy level structure of the α-emitting isotope 244Cm 3+ ( t 1/2=18.1 years) doped into single crystals of YPO 4 has been studied using site-selected laser spectroscopic methods. Electronic transitions between the nominal 8S 7/2 ground state and the 6D 7/2 state of Cm 3+ were utilized to characterize the effects of α-decay-induced structural damage. The total splitting of the four doublets in the ground multiplet is 12.5 cm −1, and that of the excited multiplet is 611 cm −1. Due to radiation damage accumulated in 17 years since the crystals were grown, the inhomogeneous line width of the 8S 7/2↔ 6D 7/2 transitions is broader than 50 cm −1 as measured without site selection. The line width of resonant fluorescence line narrowing (RFLN) is less than 1 cm −1 at 4 K. A total of 12 satellite lines were observed symmetrically spacing about the RFLN line. The position, width, and intensity of these satellite lines have been analyzed to gain information on the electronic and structural properties of the actinide ions in the disordered lattice of Cm 3+:YPO 4.