The Influence of Size Effect in the Exciton Energy Spectrum of Inert Element Clusters upon the Exciton Energy Relaxation

The influence of the size effect in the exciton energy spectrum on exciton relaxation in argon, krypton, and xenon clusters is investigated by the method of VUV cathodoluminescence spectroscopy. It is found that as the average cluster size is decreased to a certain critical value Nc∼160-190 atoms/cluster a blocking of the usual one-phonon channel of exciton energy relaxation occurs when the increasing distance between successive excitonic levels in the band reaches the phonon Debye energy. This leads to the appearance of another channel of relaxation (suppressed in the solid) that ends in the desorption of excited atoms and molecules from rare gas clusters