CO2 laser absorption and saturation studies of molecular impurities in alkali halide crystals

The objective of this research program has been to explore the equilibrium and non-equilibrium dynamical properties of ReO4- molecules embedded in alkali halide lattices using electromagnetic radiation. Both incoherent sources and CO2 laser radiation have been used to explore the full dynamic range of the molecular vibrational modes. To achieve this objective stable molecular dopant - alkali halide combinations have been fabricated which have vibrational modes near the CO2 laser frequencies. In order to uncouple the molecular modes from the lattice modes, to simplify the analysis as much as possible, low temperature spectroscopic measurements were required. In general, it was found that the molecular vibrational modes in the low temperature quiescent lattice had extremely narrow linewidths (less than 0.1 cm-1) so that most of the coincidences with the CO2 laser lines were eliminated