Vibrational Relaxation of Very Highly Excited Azulene: Collisional Transition Probabilities in the Quasi-Continuous Energy Range

Abstract

Very highly vibrationally excited molecules are involved in various molecular processes. In particular they play a crucial role in unimolecular and recombination reactions, in which collisional deactivation or activation are essential for a complete dynamic description. Hence there is a strong motivation for direct measurements of collisional deactivation in the energy range of most interest for chemical reactions. However in the larger polyatomic molecules the densities of states quickly rise to extremely high values (e.g. lt 10¹² cm⁻¹ in toluene at E = 20000 cm⁻¹). In this quasi-continuous range of rovibrational states various spectrocopic techniques have been used for time resolved observation of intermolecular vibrational relaxation. All of them can give access to only one characteristic parameter of collisional energy transfer, <ΔE>, the average amount of energy transferred per collision.