Picosecond Time-Resolved Spectroscopic Study of Vibrational Relaxation Processes in Alkali Halides

Abstract

The vibrational dynamics of fluorescent defects in alkali halides are interesting for a number of reasons. Information on electron-phonon interactions, relaxation of localized excitations and energy transfer phenomena may be obtained from a detailed study of the fluorescence properties at short times after optical excitation. In particular, the vibrational state, or states, of an impurity center may be directly determined from the time-resolved fluorescence spectrum under certain conditions, revealing details about internal energy relaxation processes. Recent advances such as the modelocked color center laser [1] and the demonstration of vibrational fluorescence [2] have provided increased interest in the vibrational properties of defects and defect systems in alkali halides.