Hi Bruce,
Thank you for the time spent trying to figure out what I am doing wrong. I am new to XAFS data processing, and it is not surprising that what was happening was due to user error!
I will go through the Athena manual as you suggested and try to set up the normalization parameters differently for our data.
Thank you, again,
Julie
Julie Muretta, Ph.D.
Materials Testing Laboratory Manager
Center for Advanced Materials Processing (CAMP)
(406) 496-4808 | jmuretta@mtech.edu
[Montana Technological University]<https://urldefense.us/v3/__https://www.mtech.edu/__;!!G_uCfscf7eWS!dJ3Z2OeOn... >
________________________________
From: Ravel, Bruce via Ifeffit
Investigating further, it seems that the problem might instead be that you are putting too much faith in the default values for the various parameters used to process the data. I mean this in the sense of the third paragraph of this page:
https://urldefense.us/v3/__https://bruceravel.github.io/demeter/documents/At...
In short, you need to be more mindful of the values of the various processing parameters. I am skeptical of the value of E0. The values of the normalization parameters are certainly incorrect for this measurement, as is clear from the green and purple lines. And when I click the orange normalization button, sure enough ... it plots the data inverted.
Playing around just a bit with the parameters explained here:
https://urldefense.us/v3/__https://bruceravel.github.io/demeter/documents/At...
and setting them to sensible values for your data completely fixes the problem.
Professorial advice: don't just trust things, make sure you understand what is happening with your data.
B
On 7/24/25 16:28, Muretta, Julie via Ifeffit wrote:
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 ZjQcmQRYFpfptBannerStart This Message Is From an External Sender This message came from outside your organization. ZjQcmQRYFpfptBannerEnd 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@mtech.edu
_Montana Technological University <https://urldefense.com/v3/__https:// urldefense.us/v3/__https://urldefense.us/v3/__https://*www.mtech.edu/__;!!G_uCfscf7eWS!__;Kg!!G... cA8TPa7rlyGu5Vmwp--j7WUFcufVPj1XStOTpvP1kNOf8HO7A1eqt_eFg- C5Pa8ui9EE_-0t6oRf1MKw_luMhQCZfKEoU_0S$__;Lw!!P4SdNyxKAPE! EsJaL2BxJwKvOZafj458aUdip_eUgtx- lizGzLA_TcIfEF8XzVrbH_6BmEsPZ2iUMyPZTovwBZO2jrF7WP-1CaTNdG6yRw$>_
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-- Bruce Ravel ------------------------------------ bravel@bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Lead Beamline Scientist, 6BM (BMM) Building 743, Room 114 Upton NY, 11973 Homepage: https://urldefense.us/v3/__http://bruceravel.github.io/home/__;!!G_uCfscf7eW... Beamline: https://urldefense.us/v3/__https://www.bnl.gov/ps/beamlines/beamline.php?r=6... Software: https://urldefense.us/v3/__https://github.com/bruceravel__;!!G_uCfscf7eWS!cT... Demeter: https://urldefense.us/v3/__http://bruceravel.github.io/demeter/__;!!G_uCfscf...
