Dielectric response function of GaPAs solid solutions in the vibrational absorption region

By taking spectra of IR transmission and reflection, attenuated total reflection, and Raman scattering, different models of the dielectric response function of GaPAs solid solutions are tested. It is demonstrated that the models accounting for the difference in the times of transverse and longitudinal vibrational relaxations, as well as the frequency distribution of TO phonons, make possible the prediction of the experimental spectra with a reasonable accuracy.