White lines in x-ray absorption

Abstract

A quantitative discussion of the white line at the $L_3$ edge of platinum and its absence at the $L_2$ edge in x-ray absorption is presented. The predominance of $d_{\frac{5}{2}}$ character in the hole in the atomic $5d$ shell of Pt is shown to persist in the unoccupied portion of the $d$ band of the metal. The total weight in the $L_3$-edge white line is calculated and found consistent with the experimental value. A brief presentation of some experimental results is given including some suggestion of the range of validity of the sudden approximation in x-ray absorption.