Effect of velocity-changing collisions upon optical coherences in a three-level system

Abstract
In this work, a theory of laser nonlinear spectroscopy and its application to the study of atomic collisions is developed. A three-level system (TLS) is considered in low-pressure gases. The effect of weak velocity-changing collisions (vcc) upon atomic coherences is introduced into the TLS equations established by Hänsch and Toschek. It appears that a TLS is suitable for the observation of the effect of vcc upon optical coherences.