OPTICAL-CONSTANTS OF ZNSE IN THE FAR INFRARED

The absorption coefficient alpha and refractive index n of bulk polycrystalline ZnSe have been derived from transmission measurements over wave-number ranges of 30-200 cm-1 and 250-600 cm-1. Infrared multiphonon structures have been found and assigned. Variations of alpha and n are satisfactorily described by a single-harmonic-oscillator model for the dielectric constant. Variations in alpha caused by multiphonon processes suggest that anharmonic lattice dynamics are important above 250 cm-1, especially for three-phonon processes, which include the fundamental TO(GAMMA) mode.