STUDIES OF FAR-INFRARED GENERATED NONEQUILIBRIUM PHONONS

Monochromatic, high occupation number phonon populations are generated using defect-induced one-phonon absorption of far infrared radiation. Phonons are detected in a time-resolved frequency selective manner us ing an absorption vibronic sideband phonon spectrometer. We use these techniques to investigate the spectral and temporal dynamics associate d with phonon decay. We concentrate on investigating phonon relaxation mechanisms which can occur in addition to spontaneous anharmonic thre e-phonon processes.