Quasistatic wing behavior of collisional-radiative line profiles

Abstract

It is shown that the conventional two-state theory of laser-induced collisional energy transfer (LICET) cannot be expected to provide an adequate description of the quasistatic wing behavior observed in a number of high-resolution LICET experiments. The theory breaks down whenever the detuning parameter \ensuremath{\Delta} of the LICET reaction is comparable to some frequency mismatch \ensuremath{\delta}\ensuremath{\omega} between either the initial or final state and a (virtual) intermediate state in the reaction. A simple extension of the conventional two-state theory is presented which leads to good agreement with experiment. For a van der Waals collisional interaction, the quasistatic wing is shown to fall off as \ensuremath{\Vert}\ensuremath{\Delta}${\ensuremath{\Vert}}^{\mathrm{\ensuremath{-}}1/2}$(\ensuremath{\delta}\ensuremath{\omega}+\ensuremath{\Vert}\ensuremath{\Delta}\ensuremath{\Vert}${)}^{\mathrm{\ensuremath{-}}3/2}$ instead of \ensuremath{\Vert}\ensuremath{\Delta}${\ensuremath{\Vert}}^{\mathrm{\ensuremath{-}}1/2}$ predicted by the two-state theory.