DEGENERATE 4-WAVE-MIXING AT BOUND EXCITONS IN II-VI SEMICONDUCTORS

The coherent and incoherent dynamics of bound exciton complexes in CdS are investigated by means of degenerate four-wave mixing and differen tial transmission spectroscopy. We observe dephasing times T2 up to 80 0 ps for the (A0, X) complex and up to 150 ps for the forbidden A(F) e xciton. The dephasing times T2 are found to be generally shorter than expected from the energy relaxation times T1. Pure dephasing processes not connected with exciton or phonon scattering are found and discuss ed in view of impurity interactions and nuclear spin-flip processes.