Spectral sharpening of the PtLedges by high-resolution x-ray emission

Abstract

The platinum ${2p}_{3/2},$ ${2p}_{1/2},$ and $2s$ x-ray absorption spectra, recorded by monitoring the fluorescence intensity with eV energy resolution, show a spectral broadening that is significantly less than the $2p$ and $2s$ core hole lifetime broadening. The background of such spectral sharpening is discussed. It is shown, experimentally as well as theoretically, that the lifetime broadening of the $2p$ and $2s$ core holes is replaced by a new lifetime broadening. It is demonstrated that from the combination of normal x-ray absorption, selective x-ray absorption, and x-ray emission, the individual lifetimes of all participating core states can be determined. The difference between the ${5d}_{5/2}$ and ${5d}_{3/2}$ densities of states can be obtained from a combination of the ${2p}_{1/2}$ and ${2p}_{3/2}$ x-ray absorption spectra. The present spectra are limited by the experimental resolution. With the prospect of an improved experimental resolution for x-ray excitation and decay, the Pt edge absorption spectra could be obtained with even better resolution, thus providing a high-resolution hard x-ray probe of the empty density of states with important advantages for in-situ and high-pressure studies.