DYNAMICS OF SELF-TRAPPING OF HOT EXCITONS STRONGLY COUPLED TO PHONONS

Dynamical self-trapping processes of photo-created hot excitons which interacts strongly with phonons are theoretically studied in an effective-medium approximation for Green functions. The previous formulation [S. Abe: J. Phys. Soc. Jpn. 57 (1988) 4029] of the resonant secondary-emission spectrum in the dynamical coherent potential approximation is extended in such a way that the effect of a finite band width of the phonon branch relevant to self-trapping is taken into account. Emission spectra calculated in this new method indicate that the intensity of hot luminescence from the metastable free state decreases with raising the incident-photon energy from the bottom of the free exciton band, suggesting that a part of hot excitons become self-trapped before they thermalize within the free exciton band states. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.