Hello Chris. - I don't have an answer regarding the R-factor. - Noise or glitch: how does I0 look like? Is the glitch you suspect visible in I0 at this energy? If you're refering to the feature that points downwards at 8A-1, it actually shifts with the spectra (I can see two groups of spectra in this k-range) so a glitch seems doubtful to me. Can you tell more about the collection of data (transmission, fluorescence, thickness of the sample, temperature, etc.)? By looking at the data, and if you confirm that I0 is glitch-free, I would be more suspicious about the data in the range 10-14A-1 than this 8A-1 feature. Cheers denis

Today's Topics:

1. k-range question & R-factor (Christopher Patridge)

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

-- Denis Testemale Institut Néel FAME beamline at ESRF +33 476 881 045