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The influence of bending waves on the warm-up behavior of exciton absorption bands in layer crystals had been investigated. The effective mass of the current carriers in the layer semiconductor Pb12 has been computed and used to obtain the values of the exciton-phonon interaction function by pseudopotential method energy spectra calculations. It was shown that the different signs of the warm-up dynamics of an exciton absorptions peak shift and existence of inversion p oints i 5 related with t he c oncurrent i nfluence o f t wo e xciton e nergy r elaxation mechanisms -o n b oth t he bending waves and the lattice phonons.

Using the model of dielectric continuum for phonons and effective mass approximation for electrons, the influence of longitudinal optical phonons on the formation of exciton spectra in polar semiconductors is studied with the Green function technique. The calculations are made in frame of the Mott-Vannier model for the exciton in nS-states (n = 1, 2 and 3) for a number of semiconductors of A 2 B 6 and A 3 B 5 groups. The results confirm that interaction of the exciton with longitudinal optical (LO) phonons manifests itself in shifting of absorption band peaks towards low-energy region. The shift differs for different states and depends on temperature. Unlike the main exciton band (n = 1), the changes in the positions and widths of the next bands (n = 2 and 3) resulted from the interaction with the LO phonons are inessential for all the crystals under analysis.

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