Cathodoluminescence spectra of free xenon clusters produced by condensation of xenon-argon gas mixtures in supersonic jets expanding into vacuum were studied. By varying initial experimental parameters, including xenon concentration, we could obtain clusters with a xenon core (300-3500 atoms) covered by an argon outer shell as well as shell-free xenon clusters (about 1500 atoms). The cluster size and temperature (about 40 K for both cases) were measured electronographically. Luminescence bands evidencing the existence of bulk and surface excitons were detected for shell-free xenon clusters. The emission from bulk excitons in small clusters is supposed to be due to processes of their multiple elastic reflections from the xenon-vacuum interface. A presence of an argon shell causes extinction of the excitonic bands. In addition, some new bands were found which have no analogs for bulk xenon cryosamples.
@article{arxiv.0710.1218,
title = {Luminescence evidence for bulk and surface excitons in free xenon clusters},
author = {O. G. Danylchenko and Yu. S. Doronin and S. I. Kovalenko and M. Yu. Libin and V. N. Samovarov and V. L. Vakula},
journal= {arXiv preprint arXiv:0710.1218},
year = {2011}
}
Comments
The final modified version will be published in Phys. Rev. A 76 (2007)