How does the presence of another isotopic species affect the ratio of the forward to backward emission fluxes in a slab geometry

Abstract Emission from a mixture of two isotope species in slab geometry is examined for slab thickness that is a multiple of half-wavelength of the resonant radiation. The forward and backward outgoing fluxes for different detuning between the two isotope species resonance frequencies are computed. The values of the initial population giving equal forward and backward fluxes or making the ratio of these two quantities an extremum are obtained. The characteristic temporal features of the field intensities and of their spectral distributions at the previous critical values are calculated.