Size dependences of electronic spectra of rare-gas clusters

Abstract The energy and optical spectra of rare-gas clusters in the region of the lowest exciton band are calculated defending on the cluster size without allowance for size structural variations. It is found that in the total size interval three optical lines are dominant; one of them is connected with bulk excitons and two with surface ones. The size dependences 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 ratio of the linear cluster size to the surface-exciton penetration depth determined only by properties of the substance. This function was calculated and found to be in a quantitative agreement with the size dependence of fluorescence excitation spectra of krypton (the experiment of Stapelfeldt et al.). Unlike the strong size dependences of the intensities, the calculated positions of the dominant lines are weakly dependent on size in a qualitative agreement with the experiment.