Hi Scott,
I collect up to 2240 eV often, because that's about where the mirror stops, but end up truncating it at 2200 eV before fitting because sometimes I end up with all sorts of non-systematic background things at higher energies, depending on the sample. I still collect the data because it helps me to troubleshoot, but I chop it before fitting because 2200 eV is the limit of what I normally consider consistently "good data." I end up with spectra that, to my eye anyway, are comparable. For dilute samples, I don't usually trust it beyond that. For concentrated samples, I don't have a problem. Thanks, Mike > On Jan 15, 2019, at 5:12 PM, Scott Calvin <dr.scott.cal...@gmail.com> wrote: > > Hi Mike, > > Is there a reason the data stops at 2200 eV—e.g., is there another edge just > above that? > > —Scott > >> On Jan 15, 2019, at 8:02 PM, Mike Massey <mmas...@gmail.com> wrote: >> >> Thanks Riti and Carlo. >> >> Riti: will give it a go, thanks! I think the data are salvageable, it's just >> a question of how... >> >> Carlo: Interesting point. In terms of how I'm fitting it, I just use the LCF >> window to do a two-component fit. Nothing super fancy. >> >> But what you're suggesting is that maybe I have a misunderstanding in the >> way I'm normalizing my data. That's entirely possible. I generally try to >> get a nice flat background by following the "flat part" of the spectra but >> in cases like this the pre- and post-edge lines end up not parallel. I can >> force it to be parallel, and that helps the fit to behave better, but ends >> up creating other normalization issues. >> >> >> Much obliged for the responses so far. >> >> >> >> Mike >> >> >> >> >>> On Jan 15, 2019, at 4:42 PM, Carlo Segre <se...@iit.edu> wrote: >>> >>> >>> Hi Mike: >>> >>> How are you trying to fit it? It looks to me like the post edge line is >>> not in the right place. You need to tune it by hand when you have such a >>> short energy range after the edge since the normalization is critically >>> dependent on how you set this line. >>> >>> carlo >>> >>>> On Tue, 15 Jan 2019, Mike Massey wrote: >>>> >>>> Hi All, >>>> >>>> >>>> Does anyone have advice for LCF of spectra with a small edge step? >>>> >>>> I've recently found myself with more and more issues fitting spectra like >>>> the one shown in the attached photo, where the spectrum is of good >>>> quality, but the fits end up not working out due to normalization (as far >>>> as I can tell). >>>> >>>> Sadly, I have so far ended up just throwing these fits out, but I'm hoping >>>> there is a better solution out there that someone might be able to >>>> recommend. >>>> >>>> One solution is "get more of the element of interest," as a beamline >>>> scientist recently told me. I'm just reluctant to really load it up in the >>>> data collection, because at 2 keV I get nervous about artifacts like >>>> self-absorption. >>>> >>>> Is there a better way? What am I missing? >>>> >>>> Thanks for your thoughts, >>>> >>>> >>>> >>>> Mike >>> >>> -- >>> Carlo U. Segre -- Duchossois Leadership Professor of Physics >>> Interim Chair, Department of Chemistry >>> Director, Center for Synchrotron Radiation Research and Instrumentation >>> Illinois Institute of Technology >>> Voice: 312.567.3498 Fax: 312.567.3494 >>> se...@iit.edu http://phys.iit.edu/~segre se...@debian.org >>> _______________________________________________ >>> 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 > > > _______________________________________________ > 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
