Angle-dependent frequency redistribution in a plane-parallel medium: External source case

A model of partial frequency redistribution for resonant scattering in a plane-parallel, optically thick atmosphere has been developed, which exactly takes into account the angular dependence of the redistribution function. The excitation source is assumed to be a continuum, external to the medium. A Monte Carlo method is employed to simulate the scattering of photons by two-level Maxwell-Boltzmann atoms with discrete lower atomic states and broadened upper states. Media with line center optical depths of up to 10/sup 6/ are considered.