Collisional Energy Transfer from Vibrationally Excited Polyatomic Molecules

Abstract

Intensities and decay rates of delayed fluorescence initiated by CO₂ laser excitation of the triplet-state molecules are used to probe collisional relaxation of vibrationally excited polyatomic molecules. Collisional efficiencies for large polyatomic molecules are found not to exceed the value of 10^?2-10^?3 even in most favourable case of vibrational energy exchange in collisions between parent molecules. At intermediate levels of excitation (1500—12000 cm^?1) the average energies <ΔE> transferred per collision with polyatomic molecules increase as vib>^rn, where m≥2, and decrease with increasing numbers of atoms in the excited molecules.