Rotational Energy Transfer in Small Polyatomic Molecules

This chapter discusses rotational energy transfer (RET) in small polyatomic molecules. It focuses on incoherent state-to-state rates that result from collisions between like molecules and on the relationship of these rates to fundamental molecular parameters. The chapter opens with a brief discussion of the applications of RET studies to other areas of science and technology. The study of the relationship between the intermolecular potential (IMP) and a wide range of important molecular phenomena is a holy grail of physical chemistry. Because collisions directly sample the IMP, a considerable amount of the RET work to date has been either directly or indirectly motivated by this quest. Another area in which RET plays a role is that of laser-isotope separation. Molecular gas lasers are complex devices and as a result, the large majority have been discovered rather than invented. Although these lasers have been extensively studied both experimentally and theoretically, the models used to describe their molecular collision dynamics ordinarily have been oversimplified. The relationship between RET studies and far infrared (FIR)-laser development is symbiotic, with many of the CO, laser pump coincidences used in RET studies having previously been discovered in searches for new FIR lasers. © 1995 Academic Press, Inc.