Manifestation of vibronic interaction in the fine structure of Cr3+ energy levels in laser crystal LiCaAlF6:Cr3+

Theoretical study of the fine structure of the 4T2g level of Cr3+ ions in LiCaAlF6 is carried out. The spin–orbit splitting of the 4T2g term in the intermediate field and the vibronic coupling with the eg local mode of crystal lattice is found. The energies of the spin–orbit components of 4T2g are found by means of diagonalization of the Eisenstein matrices using the parameters (Dq,B,C,ζ) corresponding to zero phonon line of 4T2g→4A2g emission. Dynamical Jahn–Teller effect in 4T2g state, which quenches the total splitting of 4T2g state by Ham effect, is taken into account. Using the Ham reduction factor, the Jahn–Teller stabilization energy has been calculated.