Time and Frequency Resolved Vibrational Spectroscopy of Matrix Isolated Molecules: Population and Phase Relaxation Processes

Abstract

This review is concerned with the dynamical properties of vibrational levels of matrix isolated molecules. The experimental methods which have been used in this field generally belong to laser spectroscopy. As a matter of fact with the development of laser sources time and frequency resolved spectroscopy has become a very useful tool for the study of relaxation processes in matrix isolated molecules. These various laser techniques are described, with a special emphasis on the recent developments in the field of tunable infrared lasers. The description of experimental methods is restricted to infrared spectroscopy for two reasons: this is the domain the author is most familiar with, and methods which employ other spectroscopic domains to probe vibrational levels in the ground or electronic states are quite similar in their principle. Of course in addition to IR spectroscopic data, important results obtained from time resolved visible or UV spectroscopy are described as well. Vibrational energy relaxation and transfer processes are then reviewed, including spontaneous emission, multiphonon relaxation, intramolecular vibration to rotation transfer, intermolecular resonant and phonon assisted vibration to vibration transfer.