Re: [Ifeffit] XANES pre-edge peak intensities

Hi Paul, I might add that careful and consistent background subtraction and normalization is required for any quantitative measurement. Carlo -- Carlo Segre Professor of Physics Illinois Institute of Technology On Jul 13, 2013, at 8:06, Scott Calvin wrote:

Hi Paul,

It shouldn't have any effect.

Presumably you measured the standards in transmission and the samples in fluorescence? If so, both should provide an accurate representation of the absorption as a function of energy, as the concentration of your samples is low enough that self-absorption is probably not a significant issue for them.

Of course, if you measured the standards in fluorescence, those spectra would suffer from self-absorption!

--Scott Calvin Sarah Lawrence College

On Jul 13, 2013, at 8:47 AM, "Bingham, Paul A" mailto:P.A.Bingham@shu.ac.uk> wrote:

Dear Ifeffit forum users

I have been working on a batch of Fe K-edge XANES data for dilute glasses some time and I have extracted pre-edge peak positions and intensities, as has been widely used in the literature, to get qualitative analysis of the Fe coordination in my samples. I have also done this for a number of mineral "standards", again as has widely been done in the literature (Grandidierite, Yoderite, Staurolite, etc). However, I have a question: as my samples are considerably more dilute (ca. 0.15 mol% Fe) than all of the mineral standards (these vary in Fe content between a few percent and 10's of percent), how realistic is it to use mineral standards such as these to provide reference points to "calibrate" the integrated pre-peak intensities from the dilute samples?

I have found nothing conclusive on this in the literature and would ask this forum for help, or any thoughts you may have on this issue. My own feeling is that concentration will have an effect on integrated pre-edge intensities and I suspect that more dilute samples are likely to give slightly higher integrated intensities than concentrated samples, but it is difficult to unpick and any thoughts or useful references dealing with such issues would be most welcome.

Many thanks in advance for taking the time to read this message and thanks for your responses!

Kind Regards

Paul Bingham _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.govmailto:Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit

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