On Thu, May 13, 2004 at 12:49:44PM -0500, Matt Newville wrote:
I don't know if this exists right now, but it wouldn't be hard and would seem to help all self-absorption corrections. Currently, Ifeffit's bkg_cl() does the opposite of this: scaling CL calculations to match experimental data for background subtraction and normalization. It would not be hard to have this report the factors used so that the XAFS could be scaled back to the CL f". The CL values for f" are tabularized in units of electrons (as natural for scattering) but that can be scaled to barns/atom. It might be better to use the McMaster or Elam tables.
This would not be too difficult to do with Bruce's perl modules or in Ifeffit itself. I'll put this on the Ifeffit to do list, but you might be able to roll something quick-n-dirty like this yourself faster than I get it in, especially since you're only working with
Ifeffit's bkg_cl() seems a good starting point I will look forward for it and try to do something... (as soon as possible)
one system.... I think all you'd have to do is scale the normalized XAFS to the edge jump from the tables.
I have noticed that sometimes it isn't enough to scale the edge jump but also to subtract a linear function at the post-edge to adapt the slope to the tabulated.
Are you working at the x-ray reflectivity critical angle (probably a property solely of the SiO2 layer, though 15A is thin!), or at a multilayer Bragg peak?
The standing wave field is shifted changing the angle of incidence in the vicinity of the first-order multilayer Bragg peak, to vary the contribution of different regions. Then XAFS measurement is done for the chosen standing wave filed position.
Anyway, this seems wonderfully complicated -- congratulations!!
Thank you very much,
Mauro
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Mauro Rovezzi