Investigations of the thermal red-shift of R1-line and the electron-phonon coupling parameter for Cr3+-doped YAl3(BO3)4 crystal

Abstract

A complete expression containing both the static factor caused by lattice thermal expansion and the vibrational factor owing to electron-phonon interaction is employed to compute the thermal red-shift of R1-line (the transition from 4A2 to one component of 2E) for YAl3(BO3)4: Cr3+ crystal. The results bring out that the static factor in sign is contrary to and in magnitude is nearly 22% of the vibrational factor. The true electron-phonon coupling parameter α’ raises about 28% in comparison with the apparent electron-phonon coupling parameter α estimated by considering only the vibrational factor. So, differing from the previous opinion, the static factor is not negligible for YAl3(BO3)4: Cr3+ crystal, and the rational analyses of the thermal shift of a spectral line and the electron-phonon coupling parameter should take both the static and vibrational factors into account.