Reflection and Absorption Edge Spectra in Mercurous Halide Single Crystals

Abstract

The reflection and absorption edge spectra in Hg₂I₂ and Hg₂Br₂ single crystals were measured in the visible and near ultraviolet region at various temperatures. The exciton transition of the lowest energy was assigned as the direct transition for E⁄⁄c between the bonding and antibonding states of the Hg–Hg bond. The high temperature steepness constant was obtained to be 0.53 in Hg₂I₂ from the analysis of the absorption edge, suggesting the strong exciton—LO phonon interaction in this crystal.