[Ifeffit] Self absorption Correction

Carlos Prieto 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).

Best regards

Carlos Prieto

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:
>Hi there,
>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,
>  Jens
>Jens Kruse
>Institute for Land Use
>Faculty for Agricultural and Environmental Sciences
>Rostock University
>Justus-von-Liebig-Weg 6
>18059 Rostock GERMANY
>Phone: +49(0)381-498 3190
>Ifeffit mailing list
><mailto:Ifeffit at millenia.cars.aps.anl.gov>Ifeffit at millenia.cars.aps.anl.gov
>Ifeffit mailing list
>Ifeffit at millenia.cars.aps.anl.gov

Carlos Prieto
Instituto de Ciencia de Materiales de Madrid CSIC
Cantoblanco, 28049 - MADRID (Spain)
Tel.: 91 3349017
e-mail: cprieto at icmm.csic.es

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