Inner-shell spectroscopy and exchange interaction of Rydberg electrons bound by singly and doubly charged Kr and Xe atoms in small clusters

Surface-site resolved Kr 3d5/2-15p and 3d5/2-16p and Xe 4d5/2-16p and 4d5/2-17p Rydberg excited states in small van der Waals Kr and Xe clusters with a mean size of = 15 are investigated by X-ray absorption spectroscopy. Furthermore, surface-site resolved Kr 4s-25p, 4s-26p, and 4s-14p-15p shakeup-like Rydberg states in small Kr clusters are investigated by resonant Auger electron spectroscopy. The exchange interaction of the Rydberg electron with the surrounding atoms and the induced polarization of the surrounding atoms in the singly and doubly ionized atoms are deduced from the experimental spectra to analyze different surface-site contributions in small clusters, assuming that the corner, edge, face, and bulk sites have 3, 5-6, 8, and 12 nearest neighbor atoms. These energies are almost proportional to the number of the nearest neighbor atoms. The present analysis indicates that small Kr and Xe clusters with = 15 have an average or mixture structure between the fcc-like cubic and icosahedron-like spherical structures.