Laser-excited infrared fluorescence in oxalyl fluoride. Relaxation in the presence of a low-energy, one-dimensional quasicontinuum

Abstract

Fluorescence has been observed from various fundamental and combination states of oxalyl fluoride excited by a Q-switched CO/sub 2/ laser. The presence of a low-frequency torsional mode in this molecule provides a one-dimensional quasicontinuum of vibrational levels at energies above the barrier to rotation about the C-C bond. Intermode vibrational relaxation rates in (COF)/sub 2/ are extremely rapid (possibly collisionless). The observed temperature dependence of fluorescence intensity and the overall rapid equilibration in (COF)/sub 2/ suggest a mechanism in which many rovibrational transitions that possess nu/sub 10/ character (e.g., 0 ..-->.. nu/sub 10/, nu/sub 10/ ..-->.. 2 nu/sub 10/, nu/sub x/ ..-->.. nu/sub x/ + nu/sub 10/, etc.) are excited by the laser. 3 figures.