Nonadiabatic theory of atomic line broadening: Redistribution calculations for Sr(1P←1S)+Ar

The close-coupled theory of collisions in a radiation field is used to calculate the absorption profile for the Sr ${}_{}{}^1{}_{}{}^{}\leftarrow _{}^1{}_{}{}^{}$S resonance line broadened by collisions with Ar. The calculations predict the polarization ratios of Sr ${}_{}{}^1{}_{}{}^{}\mathrm{P}$ fluorescence following line wing excitation by either linear or circular polarized light. Ab initio calculations were used to obtain the ground and excited SrAr molecular-potential curves, which were adjusted to give improved agreement with experiment. The radiative-scattering theory gives a unified description of the absorption coefficient and polarization redistribution from the small detuning impact limit region to the far spectral wings. The cross sections for elastic and inelastic depolarizing collisions of Sr ${}_{}{}^1{}_{}{}^{}\mathrm{P}_1^{}{}_{}{}^{}$+Ar were also calculated. The calculated absorption coefficient, impact-broadening rate, linear- and circular-polarization ratios, and depolarization rate coefficients are for the most part in good agreement with experiment.