Dear Valerie,
The reason why I'm currently not using Larch for my data-evaluation chain is, that I didn’t found some features (like energy calibration; not as I use it; like Calibration of references, absorption and fluorescence spectra in one group) in Larch, which I need for my data evaluation process. They might be there, but I didn’t found them. for the XANES data evaluation your energy region might be a bit to short to fit a good background to the data. Anyway you have to fine-tune the parameters to reach a good background fit in the XANES region. While the automatic process in Athena produces quite good results for a lot of absorption edges, one has to be careful not add artefacts to the data in the XANES. Best regards Stefan > Am 08.03.2021 um 14:17 schrieb Schoepfer, Valerie > <valerie.schoep...@usask.ca>: > > Hi Chris and Adam, > > I'm actually looking at Mo, so the energy range is from about 19800 through > 20200 eV on a Si(220) monochromator. (But thank you for your Fe offer!) > The standards seem to be all from the Canadian Light Source, but going as far > back as 2013... > I'm not looking to make the LCF perfect at this point, but it does seem like > the deeper I go, the less confident I am that I have the correct standards. > > I'm doing alright in Athena with respect to the process, its just that I > can't get Larch to align properly. I'll probably just use Athena for data > prep, Larch just seemed nice to learn. > But then in Athena I run into trouble with incorrect standards. One thing > after another, you know? > > Thanks- > Valerie > > -----Original Message----- > From: Ifeffit <ifeffit-boun...@millenia.cars.aps.anl.gov> On Behalf Of > ifeffit-requ...@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 phish...@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-requ...@millenia.cars.aps.anl.gov > > You can reach the person managing the list at > ifeffit-ow...@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 <newvi...@cars.uchicago.edu> > To: XAFS Analysis using Ifeffit <ifeffit@millenia.cars.aps.anl.gov> > Subject: Re: [Ifeffit] Larch energy calibration > Message-ID: > <ca+7esbrgytdjidl4x+rcuei+dfml3duyg-r2r-fhffeqshs...@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > Hi Valerie, > > On Tue, Mar 2, 2021 at 10:48 AM Schoepfer, Valerie < > valerie.schoep...@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 > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/attachments/20210303/99a209b2/attachment-0001.htm> > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > Ifeffit mailing list > Ifeffit@millenia.cars.aps.anl.gov > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit > > > ------------------------------ > > End of Ifeffit Digest, Vol 217, Issue 3 > *************************************** > > _______________________________________________ > Ifeffit mailing list > Ifeffit@millenia.cars.aps.anl.gov > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit
