Dear Valerie Which Fe standards are you looking to compare? I have a large collection of Fe references collected from the SuperXAS beamline all relatively recently and are all calibrated using Fe reference foil measured simultaneously. Using a Si(111) monochromator: Fe2O3 Fe3C Fe5C2 Fe3O4 FeO Ferrihydrite Goethite Lepidrocrite FeCl3.xH2O FeCl2 FeSO4 FeAmmoniumSulfate Fe_Nitrate Using Si(311) monochromator: FeO Fe2O3 Geothite Lepidrocrite Ferrihydrite FeIII_Hexacyanoferrate Fephthalocyanine Fetetraohenylporphyrine FePhenanthroline Fephthalocyanine chloride FeII_Hexacyanoferrate FeBisglycinate FeAmmoniumSulfate Fe2EDTA Fe3EDTA The monochromator crystal choice affects the shape of the XANES due to the relative energy resolution of the crystal. Regards Adam __________________________________________ Paul Scherrer Institut Adam Hugh Clark WLGA/129 Forschungsstrasse 111 5232 Villigen PSI Schweiz Telefon: +41 56 310 41 51 E-Mail: adam.clark@psi.ch -----Original Message----- From: Ifeffit On Behalf Of ifeffit-request@millenia.cars.aps.anl.gov Sent: Freitag, 5. März 2021 17:58 To: ifeffit@millenia.cars.aps.anl.gov Subject: Ifeffit Digest, Vol 217, Issue 4 Send Ifeffit mailing list submissions to ifeffit@millenia.cars.aps.anl.gov To subscribe or unsubscribe via the World Wide Web, visit http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit or, via email, send a message with subject or body 'help' to ifeffit-request@millenia.cars.aps.anl.gov You can reach the person managing the list at ifeffit-owner@millenia.cars.aps.anl.gov When replying, please edit your Subject line so it is more specific than "Re: Contents of Ifeffit digest..." Today's Topics: 1. Re: Larch Energy calibration (Schoepfer, Valerie) 2. Re: Larch Energy calibration (Christopher Patridge) ---------------------------------------------------------------------- Message: 1 Date: Fri, 5 Mar 2021 16:06:22 +0000 From: "Schoepfer, Valerie" To: "ifeffit@millenia.cars.aps.anl.gov" Subject: Re: [Ifeffit] Larch Energy calibration Message-ID: Content-Type: text/plain; charset="us-ascii" Hi Matt, The backstory is that I'm trying to find which standards will define my samples, so I am pulling standards from different beamlines and years to get a basic linear combination fit, to run new standards myself when I have more beamtime. I'm able to do it in Athena- where you more or less: 1. Assign E0 to the first peak in the first derivative of your standard reference foil. 2. Calibrate one standard reference foil to the theoretical edge energy. 3. Ensure E0 is right/adjust E0 for all samples and sample foils. 4. Align reference foils to the standard reference foil, because the foil will pull the sample with it. But in Larch, maybe I'm unsure about the groups function? I'm not convinced the reference foils 'follow' the sample spectra. If the reference and samples aren't tied together, how do you align samples when your energies are off because of different beamlines or years or people not as careful to calibrate the beamline energy? My first thought was using the first derivative peak of your sample, but if your edge energy shifts because of oxidation state changes, what do you use then? I'm still trying to form my question, so let me know if this still doesn't make much sense. Thanks! Valerie -----Original Message----- From: Ifeffit On Behalf Of ifeffit-request@millenia.cars.aps.anl.gov Sent: Thursday, March 4, 2021 12:00 PM To: ifeffit@millenia.cars.aps.anl.gov Subject: Ifeffit Digest, Vol 217, Issue 3 CAUTION: External to USask. Verify sender and use caution with links and attachments. Forward suspicious emails to phishing@usask.ca Send Ifeffit mailing list submissions to ifeffit@millenia.cars.aps.anl.gov To subscribe or unsubscribe via the World Wide Web, visit http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit or, via email, send a message with subject or body 'help' to ifeffit-request@millenia.cars.aps.anl.gov You can reach the person managing the list at ifeffit-owner@millenia.cars.aps.anl.gov When replying, please edit your Subject line so it is more specific than "Re: Contents of Ifeffit digest..." Today's Topics: 1. Re: Larch energy calibration (Matt Newville) ---------------------------------------------------------------------- Message: 1 Date: Wed, 3 Mar 2021 18:38:24 -0600 From: Matt Newville To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] Larch energy calibration Message-ID: Content-Type: text/plain; charset="utf-8" Hi Valerie, On Tue, Mar 2, 2021 at 10:48 AM Schoepfer, Valerie < valerie.schoepfer@usask.ca> wrote:

Hi,

I am using Larch XAS Viewer for the first time to analyze some Mo XANES data. It is fairly straightforward, however I am running into problems with energy calibration, which leads to problems with Linear Combination Fitting.

Right now, which is likely wrong, I?m calibrating the energy of a standard to the theoretical edge, then auto-aligning the samples to the standard. But how do reference foils fit in here? Reference foils don?t seem to be tied to the sample like they are in Athena. Should I be manually aligning?

Is there a general guidance or work flow?

It's possible that I do not fully understand the question or that this answer will veer a bit off the topic of your question. For sure, energies need to be aligned properly for any multi-spectra comparison or linear method to work well. But it should be that you will have groups of spectra that all share a consistent energy calibration, say from the same beamline/beamtime. If you do have a reference channel for every measurement, you can compare those reference channels. Ideally, these will not vary for every measurement - that would indicate a serious problem. So, I think you should be able to group spectra together as uniformly calibrated (hopefully all data from a day or more of beamtime at a particular beamline) and then make sure that the different groups of spectra. Does that seem reasonable? I have to admit that at my beamline I don't often have the luxury or need to run a reference foil for every scan, so we calibrate consistently ahead of time. I'm sure that leads to a bias in the software. I guess I forgot that Athena had the ability to read and tie a second spectrum as a "reference" and use that to auto-apply calibration. Is it generally necessary to calibrate many spectra individually, or do people find that doing them in a few large groups is sufficient? --Matt