Sample-related distortions to measured data

This page contains information about various problems the XAS experimentalist might encounter which are related to the physical nature of the sample. The problems include overabsorption (sometimes called, possibly wrongly, self absorption), sample thickness effects, and sample inhomogeneity (or pin hole) effects.

Tutorials and software

• A treatment of overabsorption, thickness, and hole effects in XAS data collection by Matthew Marcus and Alain Manceau. Source document: A. Manceau, M.A. Marcus, N. Tamura (2002) Reviews in Mineralogy and Geochemistry, 49, 341-428. DOI:10.2138/gsrmg.49.1.341

• Daniel Haskel’s page about his Fluo program, which corrects XANES data for self-absorption in certain situations. The Fluo document contains a mathematical derivation of a simple self-absorption correction.

• The Athena program offers several algorithms which attempt to correct for self-absorption. Here is the relevant document page.

• A discussion on self-absorption from the Ifeffit mailing list.

Literature references

1. E. A. Stern and K. Kim, Thickness effect on the extended-x-ray-absorption fine-structure amplitude, Phys. Rev. B (1981) 23:8 pp 3781-3787 DOI:10.1103/PhysRevB.23.3781

2. K-q. Lu and E. A. Stern, Size effect of powdered sample on EXAFS amplitude, Nucl. Instrum. and Methods (1983) 212, pp. 475-478 DOI:10.1016/0167-5087(83)90730-5

3. D. L. Brewe, D. M. Pease, J. I. Budnick, Corrections of residual fluorescence distortions for a glancing-emergence-angle x-ray-absorption technique Phys. Rev. B 50, 9025-9030 (1994). DOI:10.1103/PhysRevB.50.9025

4. A. Ryazhkin, Y. Babanov, M. Takafumi, Thickness inhomogeneity and fluorescence effects in EXAFS spectroscopy for powder samples: solution of the inverse problem. J. Synchrotron Rad. (2001), 8, 291-293. DOI:10.1107/S0909049500020926

5. A. I. Frenkel, D. M. Pease, J. I. Budnick, P. Shanthakumar, T. Huang, Application of Glancing Emergent Angle Flourescence for Polarized XAFS Studies of Single Crystals J. Synchrotron Rad. 14, 272-275 (2007) DOI:10.1107/S0909049507014409

6. A. Manceau, M. A. Marcus, N. Tamura, in Quantitative speciation of heavy metals in soils and sediments by synchrotron X-raytechniques”, in Applications of Synchrotron Radiation in Low-Temperature Geochemistry and Environmental Science, P. Fenter, N. C. Sturchio, Eds., Reviews in Mineralogy and Geochemistry, Mineralogical Society of America, Washington DC, 49, 341-428 (2002) DOI:10.2138/gsrmg.49.1.341

7. C. H. Booth, F. Bridges, Improved Self-Absorption Correction for Fluorescence Measurements of Extended X-Ray Absorption Fine-Structure, Physica Scripta, T115, 202-204 (2005). DOI:10.1238/physica.topical.115a00202