Background Proportional Enhancement of the Extended Fine Structure in Nonresonant Inelastic X-ray Scattering

TL;DR

This study presents new measurements and calculations of non-resonant inelastic x-ray scattering from Mg and Al, revealing enhanced extended fine structure at high momentum transfers, which could improve material analysis techniques.

Contribution

It introduces a novel understanding of background enhancement in NRIXS, linking atomic background increase with momentum transfer, applicable to low-Z element materials.

Findings

Extended oscillations observed beyond 150 eV past binding energy.

Atomic background increases with momentum transfer q.

Enhanced fine structure amplitude correlates with background enhancement.

Abstract

We report new measurements and calculations of the non-resonant inelastic x-ray scattering (NRIXS) from Mg and Al for a wide range of momentum transfers, q. Extended oscillations in the dynamic structure factor S(q,w) due to scattering from the 2p and 2s orbitals (i.e. L-edges) are observed out to more than 150 eV past the binding energy. These results are discussed in context of the recently proposed representation of S(q,w) for core shells as an atomic background modulated by interference between different photoelectron scattering paths, in analogy to the standard treatment of extended x-ray absorption fine structure. In agreement with this representation, we find a strong increase in the atomic background with increasing q with a concomitant enhancement in the amplitude of the extended fine structure. This effect should be generic and hence may enable improved measurement of the extended fine structure in a wide range of materials containing low-Z elements.