Dissociation and Vibrational Relaxation of XeF by Various Collision Partners

The removal rates of the lower levels of XeF strongly affect the overall efficiency of the XeF excimer laser operating on the B yields X transitions. We have deduced the removal rates of XeF(X,v = 3) in krypton, xenon, nitrogen, and carbon dioxide and the removal rates of XeF(X,v = 0) in sulfur hexafluoride by monitoring the populations of vibrational levels formed by the photolysis XeF2. The time history of the selected vibrational population is monitored with a continuous-wave (cw) tunable dye laser tuned to an absorption feature of the selected vibrational/rotational level. The studies show a rapid vibrational relaxation followed by a common decay rate of the coupled vibrational levels. The rare gases were found to remove XeF (X) with rate coefficients that differed from one another by less than a factor of 1.6. Larger removal rate coefficients were measured for molecular collision partners, with XeF2 having the largest rate coefficient. Rate coefficients were also determined for the concerted vibrational relaxation of v = 3 although the values do not represent state-to-state rate coefficients. Fast vibrational relaxation is required to empty the lower levels of the laser transitions so the vibrational bottlenecking does not terminate laser action prematurely. Keywords: Reaction kinetics.