[Ifeffit] Self absorption Correction
cprieto at icmm.csic.es
Mon Feb 2 09:59:19 CST 2009
Let me give you an old reference (but still
usefull) for the self absorption treatment:
R. Castañer and C. Prieto, "Fluorescence
detection of EXAFS in thin film samples", J. de
Phys. III (France), 7, 337-349 (1997).
At 15:51 02/02/2009, you wrote:
>Since no one has answered yet, I'll chime
>in. First let me direct you to a discussion of
>self-absorption and other sample-related
>(this is a link from the tutorials page of <http://www.xafs.org>www.xafs.org).
>As for your questions:
>I think that you should use the non-normalized
>XANES data to perform the SA correction.
>for the angle-in and angle-out meanings, see
>Grant Bunker's paper on self-absorption
>Now, how do you determine if you have
>self-absorption effects? I have to defer here
>to those with more experience. What you suggest
>sounds appropriate, but I'm not sure how you
>could determine this without studying multiple
>concentrations of your absorber and watch the
>signals, i.e. does a 10% increase in absorber
>concentration translate to a 10% increase in
>fluorescence yield (similar to what Matthew
>Marcus and Alain Manceau describe in their
>paper, from the over-absorption link above).
>On Fri, Jan 30, 2009 at 11:49 AM, Jens Kruse
><<mailto:jens.kruse at uni-rostock.de>jens.kruse at uni-rostock.de> wrote:
>I have measured a pure reference compound with high absorber
>concentration in fluorescence mode (P K-edge XANES). I tried to use the
>Self absorption correction included in Athena but I don't really
>understand the results.
>Fist: Do I have to use the edge step normalized spectrum or the spectrum
>without normalization ? I tried both and the results of course a quite
>different. I would rather use the not normalized spectrum.
>Second: the value "Angel in" is this the angle between the incident
>beam and the sample surface" and "Angle out" the angle between the
>sample surface and the detector position?
>Third: More general- How can I identify a spectrum suffering self
>absorption? Just comparing the relative peak intensities of total
>electron yield signal with the fluorescence yield signal ?
>thanks a lot for your comments,
>Institute for Land Use
>Faculty for Agricultural and Environmental Sciences
>18059 Rostock GERMANY
>Phone: +49(0)381-498 3190
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