Energy transfer properties and mechanisms

The overall objective of the research carried out under this program is to determine the principles of collisional energy transfer and use them in predictive models and theories. In order to accomplish this goal, energy transfer properties must be determined and then analyzed to discern the underlying principles involved. In this laboratory, the experimental determination of energy transfer parameters is based on techniques that use physical properties to monitor the amount of energy in excited molecules. These techniques differ from chemical methods, based on unimolecular reaction studies, which are susceptible to interferences from complex chemical mechanisms and other complications. The physical methods have their own weaknesses and limitations, however, and much of our effort has been directed toward gaining a better understanding of these deficiencies. Two physical techniques have been proved to be particularly useful: time-resolved infrared fluorescence and time-dependent thermal lensing. As described later, we will shortly begin work using resonance enhanced multiphoton ionization techniques to investigate energy transfer in bulbs and ''half collisions'' in free jets. We also have been completing some calculational efforts to model formation of polycyclic aromatic hydrocarbons in stellar atmospheres