INFRA-RED ABSORPTION OF BERYLLIUM IN CADMIUM TELLURIDE .2.

The dispersion curves and normal modes of vibration of CdTe have been calculated using a shell model. The single-phonon and combined two-phonon density of states have been computed and the latter is compared with measured two-phonon infra-red absorption. The infra-red absorption induced in CdTe by Be impurity is also calculated and compared with experiment. A resonance mode of Be is observed at 61 cm-1 and a local mode at 391 cm-1; calculated values of these modes obtained using a defect mass approximation are in good agreement with experiment. The structure of observed side bands arising from a simultaneous excitation of the local Be mode and lattice band modes is discussed.