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ifeffit@millenia.cars.aps.anl.gov

July 2025

4 participants
2 discussions

Query: abnormal FT-EXAFS peak at ~1.1A
by Huaming 24 Dec '25

24 Dec '25

Hello! I faced an issue with fitting of FT-EXAFS data (Rh@zeolite) with Artemis. There is one distinct peak located at ~1.1 angstron. The intensity is comparable to the nearby peak of Rh-O scattering. I wonder the peak (~1.1A) is a real peak or just noise. Raw data is enclosed. Another question is why S02 can be negative in data fitting with Artemis. Cheers, Huaming

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Problems with linear combination fitting S-XANES data in Athena
by Muretta, Julie 28 Jul '25

28 Jul '25

Hello, First of all, thank you all so very much for offering this platform to address XAS data processing!! It is wonderful to know it is available. I am having a problem using Athena "Linear Combination Fitting" with x-ray fluorescence data from SSRL. Last year, we collected sulfur K-edge XANES data at SSRL, beamline 4-3 and processed them using SixPack (averaging 5 sweeps and normalization) and then used Athena to conduct linear combination fitting of the XANES region. It worked great! This year's data are presenting a problem when I get to the LCF step, however. When I import the sample data .mu file into Athena and plot it by pressing the orange "E" button, the normalized spectrum looks like it should (albeit noisy and sometimes not the best data, but that is not Athena's fault). When I attempt to apply the Linear Combination Fitting algorithm, fitting a number of spectra from reference samples also collected last year and this year, Athena inverts the sample.mu spectrum (between -1 and 0 rather than 0 and 1). It does not invert old or new reference sample spectra. When I try this with old data, using old and new reference sample spectra, I do not have this problem. With the inverted sample spectrum, it often does not find a fit, but sometimes it does. Attached is an example Athena project file, the .mu file, and a plot of the output of a test fit, for your reference. I am hoping someone can please help me figure out why this is happening. I cannot see anything wrong, based on my limited experience, but hopefully it is something I have done wrong that can be easily corrected. Thank you in advance, Julie Julie Muretta, Ph.D. Materials Testing Laboratory Manager Center for Advanced Materials Processing (CAMP) (406) 496-4808 | jmuretta(a)mtech.edu [Montana Technological University]<https://urldefense.us/v3/__https://www.mtech.edu/__;!!G_uCfscf7eWS!cA8TPa7r… >

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