Determination of total x-ray absorption coefficient using non-resonant x-ray emission

TL;DR

This paper introduces a novel method using angle-dependent inverse partial fluorescence yield (IPFY) to directly measure the total x-ray absorption coefficient, providing accurate, bulk-sensitive, and parameter-free XAS measurements, especially useful for insulating samples.

Contribution

The study demonstrates that angle-dependent IPFY can directly determine the total x-ray absorption coefficient in absolute units without free parameters, improving accuracy over traditional fluorescence and electron yield methods.

Findings

IPFY provides a bulk-sensitive measure of x-ray absorption.

The method accurately determines $mbda(E)$ in absolute units.

IPFY is effective for insulating samples where other methods fail.

Abstract

An alternative measure of x-ray absorption spectroscopy (XAS) called inverse partial fluorescence yield (IPFY) has recently been developed that is both bulk sensitive and free of saturation effects. Here we show that the angle dependence of IPFY can provide a measure directly proportional to the total x-ray absorption coefficient, $\mu(E)$. In contrast, fluorescence yield (FY) and electron yield (EY) spectra are offset and/or distorted from $\mu(E)$ by an unknown and difficult to measure amount. Moreover, our measurement can determine $\mu(E)$ in absolute units with no free parameters by scaling to $\mu(E)$ at the non-resonant emission energy. We demonstrate this technique with measurements on NiO and NdGaO$_3$. Determining $\mu(E)$ across edge-steps enables the use of XAS as a non-destructive measure of material composition. In NdGaO$_3$, we also demonstrate the utility of IPFY for insulating samples, where neither EY or FY provide reliable spectra due to sample charging and self-absorption effects, respectively.