Computational study of a molecular collision process in the presence of an intense radiation field: Enhanced quenching of F by Xe in the 248-nm light of the KrF laser

Abstract

A model is developed to describe collisional quenching in the presence of a radiation field within a close-coupled formalism. In this model the collision dynamics are treated in a simplified manner, ignoring Coriolis and angular-potential coupling, thus reducing the computational complexity of the problem. The model hence focuses on the radial coupling of the collision system to the radiation field. The process investigated with this model is the quenching of fluorine by xenon in the 248-nm radiation field of a KrF laser. The mechanism for the radiative contribution to the quenching cross section is absorption of a photon by XeF followed by stimulated emission of a photon to the XeF ground state, the intermediate state being an excimer state of the XeF molecule. Thus, there is no net loss of photons from the radiation field and (in the language of perturbation theory) the process is of second order. The quenching cross section is calculated for collision energies in the range 0.05 to 0.25 eV and for field intensities of 0, 10, 100, and 1000 GW/${\mathrm{cm}}^{2}$. Results indicate that field intensity of 10-100 GW/${\mathrm{cm}}^{2}$ should have an experimentally observable effect on the quenching of fluorine by xenon at thermal collision energies.