Self-trapped hole in silver chloride crystals: A pulsed EPR/ENDOR study at 95 GHz

Abstract

A high-frequency electron nuclear double-resonance study of the self-trapped hole in silver chloride is presented. The data provide direct information about the spatial distribution of the unpaired electron at the silver and chlorine sites and of the electrical field gradient distribution at the chlorine sites of the self-trapped hole. The wave function of the self-trapped hole is shown to be essentially located in the plane perpendicular to the elongation axis. In general our results show that the hole is distributed on Ag (\ensuremath{\sim}30%) and Cl (\ensuremath{\sim}70%) sublattices and confirm the admixture of $4d$ $({\mathrm{Ag}}^{+})$ and $3p$ $({\mathrm{Cl}}^{\ensuremath{-}})$ wave functions at the valence band maximum. Information about the geometric structure of the self-trapped hole is obtained which confirms that the self-trapping of holes in silver chloride at low temperatures results from a ``bare'' Jahn-Teller distortion, not accompanied by a vacancy or impurity.