Abstract

Quantum beats in time-resolved resonant ligt Scattering were recently demonstrated to be a powerful tool for the investigation of excitonic systems.^[1,2] The beating structure originates from the quantum mechanical superposition of nearly degenerate states that are coherently excited by a short optical pulse. The oscillation frequency provides the energy splitting of the states which, compared to spectral measurements, can be determined with higher resolution and independent of inhomogeneous broadening. Even more important, the beat signal amplitude is a measure of the coherent (Ramanlike) contribution to the total emitted intensity. Its damping directly traces the time evolution of the exciton system from the initially prepared coherent state into the final incoherent ensemble, the analysis in terms of inelastic and elastic scattering processes giving a quantitative picture of exciton dephasing.

© 1992 IQEC