Laser-induced ionising collisions in alkali vapours

Abstract

The semiclassical theory is developed for a simultaneous collisional and radiative process,, and applied to the laser-induced ionisation in a collision of two excited alkali atoms (in their lowest n²P states) in a laser field. Perturbation theory is used to evaluate the probability for this process in the case of straight-line paths at large impact parameter. The collision perturbation is taken to be the dipole-dipole interaction between the two atoms, which together with the dipole interaction with the radiation leads to the occurrence of s and d intermediate atomic states and p and f final states for the ejected electron.