Influence of atomic motion on the shape of two-photon resonance in gas

Abstract

A gas of three-level atoms with Λ configuration of energy levels was taken as an example to demonstrate that the influence of particle motion on the two-photon resonances extends further than the residual Doppler shift (k 1−k 2)v. In particular, a narrow dip in the absorption spectrum (“dark” resonance) undergoes substantial narrowing, as compared to the atoms at rest. The width of this resonance is studied nonperturbatively as a function of the intensities of probe and strong fields.