X-ray absorption by a microgranular sample

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Timoshenko, Janis ; Kordus, David ; Mathiesen, Jette K. ; Hejral, Uta ; Zeller, Patrik ; Behrendt, Gereon ; Öztuna, Eylül ; Wang, Jihao ; Gheisari, Zahra ; Eckert, Rene ; Reitmeier, Stephan ; Reitzmann, Andreas ; Ruland, Holger ; Folke, Jan ; Lunkenbein, Thomas ; Roldan Cuenya, Beatriz:
X-ray absorption by a microgranular sample.
In: Physical Review B. Bd. 112 (2025) . - 024105.
ISSN 0163-1829
DOI: https://doi.org/10.1103/bqg7-kb24

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Abstract

Sample homogeneity on the microscopic scale is critical for the reliable interpretation of x-ray absorption spectra collected in transmission mode. Unfortunately, it is not always easy to ensure it in practice. Especially in operando studies of catalysts and functional materials, the microstructure of the sample can evolve during its operation and even become the key descriptor for understanding structure-property relationships of the material, as exemplified by the transformations taking place in technical iron-based catalysts for ammonia synthesis under operating conditions. Here we present a simple approach for the identification and quantification of the material's microgranular structure effect on its x-ray absorption spectrum. We demonstrate that the quantitative information on the sizes of microscopic sample particles can be extracted from the observed distortions in the x-ray absorption near-edge structure spectra. The obtained insight can also be used to correct for the artifacts in extended x-ray absorption fine structure fitting, associated with the presence of microscopic inhomogeneities in the sample.