Anharmonic Relaxation Times of Molecular Vibrational Modes in Alkali Halide Crystals

Abstract

Low-temperature infrared-saturation and hole-burning measurements have been performed on an internal vibrational mode of a spherical-top molecule embedded in a variety of alkali halide crystals. The vibrational relaxation times $T_1$ and $T_2$ satisfy the relation $T_2\cong 2T_1$ but $T_1$ (⩽ 38 nsec) is orders of magnitude smaller than expected for multiphonon decay. A study of the alkali halide dependence of these relaxation times suggests that a specific combination of internal, local, and band modes is involved in the decay process.