Magnetic circular dichroism of atomic rhenium in a krypton matrix: Large ground state crystal field splitting

Abstract

The absorption and magnetic circular dichroism (MCD) spectra of the rhenium atom isolated in a krypton matrix at 10 K are presented. Assignment of all optical bands observed in the 510–230 nm range is made. Expressions are developed to determine the ground state crystal (matrix) field splitting using the MCD saturation technique on nonoverlapped optical bands. A large crystal field (CF) splitting of 7.5±3.0 cm−1 is found and attributed to two sources, both of which must be present for the splitting to occur: (1) the spin–orbit mixing of the low-lying 4P5/2 state (11 600 cm−1) into the 6S5/2 ground state and (2) the crystal (matrix) field effect on this mixed state by the tetradecahedral substitutional matrix site. Band moment expressions are extended to account for a large ground state CF splitting and are used to determine the excited z 6PJ state spin–orbit splitting parameter (−102 cm−1). Finally, evidence for Jahn–Teller activity in the z 6PJ state is presented from an analysis of the modified MCD/absorption band moment expressions.