- Physical Review Journals
All JournalsPhysics Magazine

Physical Review B

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access

X-ray absorption by a microgranular sample

Janis Timoshenko1,*, David Kordus1, Jette K. Mathiesen1,†, Uta Hejral1, Patrik Zeller2, Gereon Behrendt2, Eylül Öztuna2, Jihao Wang2, Zahra Gheisari2 et al.

Rene Eckert3, Stephan Reitmeier3, Andreas Reitzmann3, Holger Ruland4, Jan Folke4, Thomas Lunkenbein2, and Beatriz Roldan Cuenya1

  • *Contact author: janis@fhi-berlin.mpg.de
  • †Present address: Technical University of Denmark, Department of Physics Fysikvej, Building 312, 2800 Kongens Lyngby, Denmark.
PDF

Phys. Rev. B 112, 024105 – Published 10 July, 2025

DOI: https://doi.org/10.1103/bqg7-kb24

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.

View figure in article

Physics Subject Headings (PhySH)

Article Text

Supplemental Material

References (45)

  1. S. Bordiga, E. Groppo, G. Agostini, J. A. van Bokhoven, and C. Lamberti, Reactivity of surface species in heterogeneous catalysts probed by in situ x-ray absorption techniques, Chem. Rev. 113, 1736 (2013).
  2. D. E. Sayers, E. A. Stern, and F. W. Lytle, New technique for investigating noncrystalline structures: Fourier analysis of the extended x-ray—absorption fine structure, Phys. Rev. Lett. 27, 1204 (1971).
  3. J. J. Rehr and R. C. Albers, Theoretical approaches to x-ray absorption fine structure, Rev. Mod. Phys. 72, 621 (2000).
  4. M. Rose and M. M. Shapiro, Statistical error in absorption experiments, Phys. Rev. 74, 1853 (1948).
  5. E. A. Stern and K. Kim, Thickness effect on the extended-x-ray-absorption-fine-structure amplitude, Phys. Rev. B 23, 3781 (1981).
  6. L. Parratt, C. Hempstead, and E. Jossem, “Thickness effect” in absorption spectra near absorption edges, Phys. Rev. 105, 1228 (1957).
  7. S. M. Heald and E. A. Stern, Anisotropic x-ray absorption in layered compounds, Phys. Rev. B 16, 5549 (1977).
  8. G. Bunker, Introduction to XAFS: A Practical Guide to X-ray Absorption Fine Structure Spectroscopy (Cambridge University Press, Cambridge, 2010), pp. 87–89.
  9. D. Gianolio, How to start an XAS experiment, in X-Ray Absorption and X-Ray Emission Spectroscopy: Theory and Applications, edited by J. A. van Bokhoven and C. Lamberti (Wiley, New York, 2016).
  10. S. Calvin, XAFS for Everyone (CRC Press, Boca Raton, FL, 2013), pp. 52–54.
  11. G. Meitzner, Experimental aspects of x-ray absorption spectroscopy, Catal. Today 39, 281 (1998).
  12. S. Heald, in EXAFS and Near Edge Structure: Proceedings of the International Conference, Frascati, Italy, September 13–17, 1982 (Springer, Berlin, 1983), p. 98.
  13. E. Voronina, D. Guy, and T. Miyanaga, Thickness effect correction in XAFS-spectroscopy: Temperature measurement approach, Nucl. Instrum. Methods Phys. Res., Sect. B 215, 525 (2004).
  14. Y. A. Babanov, A. Ryazhkin, and T. Miyanaga, Correction of x-ray absorption spectra for thickness inhomogeneity and fluorescence of sample, Nucl. Instrum. Methods. Phys. Res. A 470, 278 (2001).
  15. A. Ryazhkin, Y. Babanov, and T. Miyanaga, Thickness inhomogeneity and fluorescence effects in EXAFS spectroscopy for powder samples: Solution of the inverse problem, J. Synchrotron Radiat. 8, 291 (2001).
  16. K.-Q. Lu and E. Stern, Size effect of powdered sample on EXAFS amplitude, Nucl. Instrum. Methods Phys. Res. 212, 475 (1983).
  17. N. Bausk, S. Erenburg, and L. Mazalov, Correction of XAFS amplitude distortions caused by the thickness effect, J. Synchrotron Radiat. 6, 268 (1999).
  18. R. Scarrow, Sample preparation for EXAFS spectroscopy, lecture notes for NSLS EXAFS course, 2002, https://docs.xrayabsorption.org/Workshops/NSLS2002/Scarrow.pdf.
  19. E. Curis, J. Osán, G. Falkenberg, S. Bénazeth, and S. Török, Simulating systematic errors in x-ray absorption spectroscopy experiments: Sample and beam effects, Spectrochim. Acta, Part B 60, 841 (2005).
  20. G. Weinberg, B. Beran, M. Muhler, R. Schlögl, A. Dent, and T. Rayment, The micromorphology of the activated iron catalyst used for ammonia synthesis, Appl. Catal. A 163, 83 (1997).
  21. W. Niemann, B. Clausen, and H. Topsøe, EXAFS studies of ammonia catalysts at synthesis conditions, Ber. Bunsengesellschaft Phys. Chem. 91, 1292 (1987).
  22. K. Dembélé et al., The Haber Bosch catalyst from solid state chemistry to mesotechnology, Adv. Energy Mater. 2500159 (2025).
  23. M. Newville, Larch: An analysis package for XAFS and related spectroscopies, J. Phys.: Conf. Ser. 430, 012007 (2013).
  24. B. Ravel, and M. Newville, artemis athena, hephaestus: Data analysis for x-ray absorption spectroscopy using ifeffit, J. Synchrotron Radiat. 12, 537 (2005).
  25. J. A. Varnell, C. Edmund, C. E. Schulz, T. T. Fister, R. T. Haasch, J. Timoshenko, A. I. Frenkel, and A. A. Gewirth, Identification of carbon-encapsulated iron nanoparticles as active species in non-precious metal oxygen reduction catalysts, Nat. Commun. 7, 12582 (2016).
  26. J. Filik et al., Processing two-dimensional x-ray diffraction and small-angle scattering data in dawn 2, J. Appl. Crystallogr. 50, 959 (2017).
  27. P. Juhás, T. Davis, C. L. Farrow, and S. J. Billinge, pdfgetx3: A rapid and highly automatable program for processing powder diffraction data into total scattering pair distribution functions, J. Appl. Crystallogr. 46, 560 (2013).
  28. C. Farrow, P. Juhas, J. Liu, D. Bryndin, E. Božin, J. Bloch, T. Proffen, and S. Billinge, pdffit2 and pdfgui: Computer programs for studying nanostructure in crystals, J. Phys.: Condens. Matter 19, 335219 (2007).
  29. A. Machida, H. Saitoh, T. Hattori, A. Sano-Furukawa, K.-I. Funakoshi, T. Sato, S.-I. Orimo, and K. Aoki, Hexagonal close-packed iron hydride behind the conventional phase diagram, Sci. Rep. 9, 12290 (2019).
  30. L. Sandoval-Diaz, M. Plodinec, D. Ivanov, S. Poitel, A. Hammud, H. C. Nerl, R. Schlögl, and T. Lunkenbein, Visualizing the importance of oxide-metal phase transitions in the production of synthesis gas over Ni catalysts, J Energy Chem. 50, 178 (2020).
  31. A. Cintins, A. Anspoks, J. Purans, A. Kuzmin, J. Timoshenko, P. Vladimirov, T. Gräning, and J. Hoffmann, ODS steel raw material local structure analysis using x-ray absorption spectroscopy, IOP Conf. Ser.: Mater Sci. Eng. 77, 012029 (2015).
  32. See Supplemental Material at http://link.aps.org/supplemental/10.1103/bqg7-kb24 for Supplemental figures and tables showing EXAFS data fitting results, validation of Eq. (9), and PDF fitting results.
  33. H. Wang et al., Correction of distorted x-ray absorption spectra collected with capillary sample cell, Nucl. Sci. Tech. 34, 106 (2023).
  34. A. S. Buthelezi, C. L. Tucker, H. J. Heerees, M. L. Shozi, H. H. van de Bovenkamp, and P. Ntola, Fischer-Tropsch synthesis using promoted, unsupported, supported, bimetallic and spray-dried iron catalysts: A review, Results Chem. 9, 101623 (2024).
  35. M. Lopez Luna, J. Timoshenko, D. Kordus, C. Rettenmaier, S. W. Chee, A. S. Hoffman, S. R. Bare, S. Shaikhutdinov, and B. Roldan Cuenya, Role of the oxide support on the structural and chemical evolution of Fe catalysts during the hydrogenation of CO2, ACS Catal. 11, 6175 (2021).
  36. H. Zhou, S. Zhang, Y. Shao, S. Liu, X. Fan, and H. Chen, Relationship between structural properties of the unsupported Ni5Ga3 catalyst and methanol synthesis activity, Ind. Eng. Chem. Res. 63, 6974 (2024).
  37. M. Onoro, S. Parnell, E. Salas-Colera, D. A. Venero, V. Martin-Diaconesu, T. Leguey, V. de Castro, and M. Auger, Secondary phases characterization by SANS and XAS of an ODS ferritic steel after thermal aging at 873 K, Nucl Mater. Energy 39, 101671 (2024).
  38. P. A. O'Day, A. Pattammattel, P. Aronstein, V. J. Leppert, and H. J. Forman, Iron speciation in respirable particulate matter and implications for human health, Environ. Sci. Technol. 56, 7006 (2022).
  39. K. Tirez, G. Silversmit, L. Vincze, K. Servaes, C. Vanhoof, M. Mertens, N. Bleux, and P. Berghmans, Speciation and fractionation of nickel in airborne particulate matter: Comparison between selective leaching and XAS spectroscopy, J. Anal. At. Spectrom. 26, 517 (2011).
  40. H. Shao, H. Isobe, G. Kitahara, H. Fukui, and A. Yoshiasa, XAFS and XRD study on Fe, Ni, and Ge in iron meteorite NWA 859, Phys. Chem. Miner. 48, 11 (2021).
  41. S. Boccato et al., Melting properties by x-ray absorption spectroscopy: Common signatures in binary Fe–C, Fe–O, Fe–S and Fe–Si systems, Sci. Rep. 10, 11663 (2020).
  42. L. Braun et al., Following the structural changes of iron oxides during reduction under transient conditions, ChemSusChem 17, e202401045 (2024).
  43. N. S. Genz et al., Operando laboratory-based multi-edge x-ray absorption near-edge spectroscopy of solid catalysts, Angew. Chem., Int. Ed. 61, e202209334 (2022).
  44. N. S. Genz, A. J. Kallio, F. Meirer, S. Huotari, and B. M. Weckhuysen, Operando laboratory-based x-ray absorption spectroscopy: Guidelines for newcomers in the field, Chemistry-Methods 4, e202300027 (2024).
  45. M. Rüscher, J. B. Jang, A. Martini, P. Bischoff, W. Frandsen, J. Timoshenko, and B. Roldan Cuenya, Laboratory-based time-resolved in situ x-ray absorption spectroscopy for tracking transformations of working electrocatalysts, Chemistry-Methods 4, 2500016 (2025).

Outline

Information

Phys. Rev. B 112, 024105– Published 10 July, 2025
  • Received 7 March 2025
  • Accepted 13 June 2025
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by Max Planck Society.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation