X-ray core states, atomic size and Moseley's law

Vinti's dipolar sum-rule for the spatial extent of quantum states was teste d on atomic K-shell and ns valence states. Agreement between radii derived from absorption spectra and from atomic-structure calculations is excellent , provided Pauli-principal-prohibited transitions are accounted for. These many-electron corrections to the single-electron sum-rule contributed less than 20% to the radii, which supports application of single-electron rules to electron-excess defects as a first approximation. We found the oscillato r strength for K-shell excitations decreases rapidly with atomic number bec ause of strength transfer to higher-lying p states. Hence, K-shell contribu tions to radiation damage decrease with increasing atomic number. A new int erpretation of Moseley's law for the X-ray K edge in terms of K-shell radii is described. (C) 2000 Elsevier Science B.V. All rights reserved.