Plasmon-two phonon interaction in PbTe_0.95S_0.05 alloy

In this work far-infrared spectroscopy in a wide temperature range was used to investigate the vibrational properties of PbTe_0.95S_0.05 single crystal. In the analysis of experimental results we are going to use dielectric function that in advance takes into account the existence of plasmon-two phonon interaction. As a result of the best fit we obtained three frequencies of coupled modes, and than calculated the values for two LO modes and ω_P. We obtained a very good agreement between the result obtained as a best fit from experimental spectra and theoretical prediction. We have found that phonons in PbTe_1–xS_x show the two-mode behavior. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)