Strong Interference Luminescence of Mixed Modes in the Neighborhood of the Critical Value of Exciton Decay

The results of a numerical calculation of the dispersion and luminescence spectra of mixed exciton modes of crystals of the CdS (\({{A}_{{n = 1}}}\)) type are analyzed depending on the decay \(\Gamma \) of mechanical excitons and the angle \(\theta \) of emission of radiation into vacuum in the vicinity of the critical values \({{\Gamma }_{c}}\) and \({{\theta }_{c}}\). It is shown that the mechanism of \({{A}_{L}}\) line formation depends significantly on the value of the light–exciton interaction parameter \({{\tilde {\omega }}_{{LT}}}\left( {{{\theta }_{c}}} \right){\text{/}}{{\Gamma }_{c}}\), the superposition of M1 and M2 waves with strongly asymmetric \({{I}_{{M1}}}(\omega )\), \({{I}_{{M2}}}(\omega )\), and symmetric \({{I}_{{12}}}(\omega )\) contours forms an almost symmetric resulting spectral contour \(I\left( \omega \right)\) with a maximum at the critical frequency \({{\omega }_{c}}\).