Normalization and convergence of x-ray absorption sum rules

A procedure is developed for quantitative applications of the sum rules for x-ray absorption spectra, e.g., for x-ray magnetic circular dichroism. The approach is based on theoretical atomic calculations of transformations relating various experimental spectra to corresponding operator-spectral densities. This approach overcomes the difficulties of background subtraction and hole-count normalization of other sum-rule analysis methods and yields quantitative values for spin and orbital moments from experimental absorption spectra.