One-phonon and multiphonon absorption in EuSe and Eu/sub 1-x/Sr/sub x/S (0 < x < 1)

Transmission and reflection measurements on single crystalline samples of stoichiometric EuSe show a number of intrinsic absorption structures in the far infrared. They are explained by one-, two-, and three-phonon processes. The results are consistent with measurements of second-order Raman scattering and agree with theoretical calculations of the density of states and phonon dispersion published earlier. The reststrahl bands of the alloys Eu/sub 1-x/Sr/sub x/S show a typical one-mode character with additional weak structures. The shift of the phonon frequencies with composition and temperature is reported. (author)