Jahn–Teller effect and electron–phonon interaction in the [formula omitted] excited state of [formula omitted] ion in [formula omitted] crystal

Abstract

The electron–phonon coupling and Jahn–Teller effect in the first excited state 4 T 2 g of Cr 3+ in K 2LiAlF 6 crystal (which has the potential for tunable solid-state lasers applications) are considered. The force constants for the a 1g and e g normal modes are calculated with the FG matrix method for the octahedral [CrF 6] 3− cluster and the Huang–Rhys factors S a 1g and S e g from the experimental value of the total Huang–Rhys factor and Stokes shift. Using these data, the changes of the metal–ligand bond lengths Δ x eq , Δ y eq = 0.072 Å (equatorial expansion) and Δ z eq = − 0.015 Å (axial compression) were estimated. The Jahn–Teller stabilization energy has been evaluated from the contour plot of the 4 T 2 g electronic state potential energy surface. The obtained results are compared with those for other fluorides; the common trends are found and discussed.