SIZE DEPENDENCES OF ELECTRONIC-SPECTRA OF RARE-GAS CLUSTERS

The energy and optical spectra of rare-gas clusters in the region of t he lowest exciton band are calculated depending on the cluster size wi thout allowance for size structural variations. It is found that in th e total size interval three optical lines are dominant; one of them is connected with bulk excitons and two with surface ones. The size depe ndences of the energy positions and intensities of the dominant lines were obtained. The intensity distribution between the surface and bulk lines was presented as a function of a single variable, viz., the rat io of the linear cluster size to the surface-exciton penetration depth determined only by properties of the substance. This function was cal culated and found to be in a quantitative agreement with the size depe ndence of fluorescence excitation spectra of krypton (the experiment o f Stapelfeldt et al.). Unlike the strong size dependences of the inten sities, the calculated positions of the dominant lines are weakly depe ndent on size in a qualitative agreement with the experiment.