On the scattering of a light pulse on a single atom perturbed by collisions with inert gas atoms

Scattering of a laser pulse on a single atom perturbed by collisions with inert gas atoms is described in terms of suitably defined cross-sections. The relations of the energy balance are explored to show the connection between attenuation and total cross-section for scattering. The different scattering channels, corresponding to the polarisation, spectral decomposition and coherence properties of the light are analysed in terms of the cross-sections. As an example we consider the scattering of a light pulse on an alkali metal atom with a frequency close to the atomic transition frequency from the ground stateS _1/2 to the first excited stateP _1/2.