TIME-RESOLVED LUMINESCENCE OF EXCITON-POLARITONS IN SOLID XENON

The decay of excitons in solid Xe is investigated with time and spectr ally resolved luminescence as a function of temperature and photon ene rgy of excitation. The luminescence of free excitons exceeds the self- trapped exciton luminescence by a factor of 50 (peak-to-peak). The FE- decay curves yield a non-exponential behaviour. They can be reproduced with Monte-Carlo simulations of the exciton-polariton transport to th e sample/vacuum interface, taking into account phonon scattering and t rapping. A new upper limit for the intrinsic self-trapping rate in the lower 10(7) s(-1) range and a surprisingly large experimental value f or the scattering length (approximate to 100 nm at T = 5 K) are deduce d. It is indispensable to discuss the decay of excitons in solid Xe in terms of the exciton-polariton model.