Memory effects in speed-changing collisions and their consequences for spectral lineshape: I. Collision regime

consistent approach to the lineshape in the binary collision regime accounting for -changing collisions based on a convenient memory function is . The of memory effects on the spectral lineshape, through -dependent line and line shifting mechanisms, are studied in detail for prototype H2-Ar system. connection between the present memory approach and the analytical model SC + D ("speed changing" and "dephasing" collisions) based on the hard collision approximation is .