Low Temperature Physics: 23, 578 (1997); https://doi.org/10.1063/1.593474 (9 pages)
Free and self-trapped excitons in rare gas cryocrystals: co-existence and mixing of states
I. Ya. Fugol` and E. I. Tarasova
B.Verkin Institute for Low Temperature Physics and Engineering, 47 Lenin Ave.,310164, Kharkov, Ukraine
( Submitted August 28, 1996, revised November 22, 1996 )
The absorption spectra of rare gas cryocrystals are calculated with taking into account the free exciton single phonon scattering and multi-phonon interaction with local lattice vibrations. A possibility of free and self-trapped excitons co-existence in the non-equilibrium states above the exciton band bottom is discussed using the comparison of free exciton energy with exciton damping values under single phonon scattering and transitions to the exciton-vibron states. It is found that at low temperatures only in xenon cryocrystals the free exciton damping is mainly controlled by the single phonon scattering through the whole exciton band. In krypton and argon crystals both types of exciton damping have comparable values. In neon the probability of transitions to self-trapped states is so high that the existence of free exciton states is doubtful.