X-ray-induced photoemission yield for surface studies of solids beyond the photoelectron escape depth

TL;DR

This paper demonstrates that the total X-ray-induced photoemission yield can be modulated by multilayer structures' Fresnel reflectivity, enabling non-invasive analysis of buried layers beyond the photoelectron escape depth.

Contribution

It introduces a method to analyze buried multilayer structures using photoemission yield modulation without detecting reflected X-rays.

Findings

Photoemission yield is modulated by multilayer Fresnel reflectivity.

The method allows extraction of individual layer thicknesses.

It enables non-invasive buried layer analysis with hard X-rays.

Abstract

X-ray-induced photoemission in materials research is commonly acknowledged as a method with a probing depth limited by the escape depth of the photoelectrons. This general statement should be complemented with exceptions arising from the distribution of the X-ray wavefield in the material. Here we show that the integral hard-X-ray-induced photoemission yield is modulated by the Fresnel reflectivity of a multilayer structure with the signal originating well below the photoelectron escape depth. A simple electric self-detection of the integral photoemission yield and Fourier data analysis permit extraction of thicknesses of individual layers. The approach does not require detection of the reflected radiation and can be considered as a framework for non-invasive evaluation of buried layers with hard X-rays under grazing incidence.