Semiclassical study of polarization-dependent optical collisions: application to Mg (

A semiclassical approach in the study of polarization-dependent optical collisions has been developed. General expressions for the cross-sections describing optical collisions of the atoms with arbitrary angular momentum and rare gas atoms in the ground state are obtained. The formation of different atomic multipoles in direct optical collision and the influence of the multipoles on light absorption in this process are considered from general positions of the semiclassical approach including the nonadiabatic dynamics of the collision. Light absorption in the far wings of the 1P → 1S atomic transition is considered in more detail. For such type of optical collision the resonance scattering is also included in the semiclassical analysis. It is obtained that there is no orientation-dependent part in the resonance cross-section describing circularly polarized light absorption. However, the alignment-dependent part describing the linearly polarized or unpolarized light absorption is significant for resonance collisions as well as for direct collisions. The calculation for the Mg(3p 1P1 → 5s 1S0)−Ar(1S0) optical collision and comparison with experimental results are presented.