Jahn-Teller and Reorientation Effects in the ESR Spectrum of the Self-Trapped Holes in Mixed Crystals AgBr_1−xCl_x. II

Abstract

Electron spin resonance study shows that holes in AgBr_0.001Cl_0.999 crystal are self-trapped as the complexes (AgBrCl₅)⁴⁻ besides the complexes (AgCl₆)⁴⁻. The complex (AgBrCl₅)⁴⁻ has a rhombic symmetry due to a Jahn-Teller effect and to a tetragonal crystal field created by a Br ligand. The energy barrier between two configurations of the complex (AgBrCl₅)⁴⁻ is estimated to be lower than those between three configurations of the complex (AgCl₆)⁴⁻, so that we can expect occurrence of a dynamic or intermediate Jahn-Teller effect for the complex (AgBrCl₅)⁴⁻. The ESR line shapes have been calculated for several values of 2Γ⁄δ, which represents the ratio of the tunneling splitting to the random strain splitting. The result shows that the low-temperature ESR spectrum of the complex (AgBrCl₅)⁴⁻ is associated with an intermediate Jahn-Teller effect.