Hi Chris, I don't see a reason to think that data is a glitch. For one thing, it's not consistent across datasets. The features also look smooth, and not so glitch-like. The spike around 8.2 inverse angstroms in some of the datasets looks a bit more like a glitch, but it's fairly modest and narrow enough not to mess you up too much.
The spacing of those features look OK--there's a double feature in some of the datasets around 6-7 inverse angstroms; it's plausible there would be another reature like that above it. In fact, I can make an argument that there's some kind of beating going on that gives a shoulder at 3.5-5, a double peak at 5-7, and two peaks at 7-8 inverse angstroms. So I would recommend including that data and seeing what it does to your fits. If that range is garbage, your fits will probably reject it. As for your second question, R-factors are always a kind of average across the data, by definition. So "total" mismatch doesn't really make sense. Off-hand, though, I don't recall how ifeffit weights the data for the purposes of calculating R-factors for multiple datasets, and that may be your question. --Scott Calvin Sarah Lawrence College On Jan 15, 2013, at 9:21 AM, Christopher Patridge wrote: > Hello Users, > > I was looking for an opinion about the chi(k) signal in a set of data I > am analyzing. Brief background, this is a set of in-situ XAS data > collected at the Fe K edge from a working electrochemical cell at a > range of potentials during charge; I did not collect the data. I suspect > the feature at ~ 8 angstroms-1, although present in all the spectra is > noise or glitch and wondered if I am being overly cautious? > > My conservative range ( k = 2-7 and R = 1-2) really constrains the model > Nidp = 3.31. Luckily, multiple datasets ( 8 ) to the rescue to give me > some flexibility. In a multiple dataset fitting, is the R-factor of the > whole set just the average or total mismatch across all the datasets or > it calculated another way? > > Working towards happiness, > > Chris Patridge > > -- > ******************************** > Christopher J. Patridge, PhD > NRC Post Doctoral Research Associate > Naval Research Laboratory > Washington, DC 20375 > Cell: 315-529-0501 > > <Athena-plot.png>_______________________________________________ > Ifeffit mailing list > Ifeffit@millenia.cars.aps.anl.gov > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit