[Ifeffit] Self-Absorption Corrections

Peter Pfalzer peter.pfalzer at physik.uni-augsburg.de
Fri Jul 25 03:59:40 CDT 2003

Hi all,

> Corwin Booth (at LBL lab, Berkeley) presented a very nice procedure
> for making these corrections for EXAFS at the conference, improving
> the work of L. Troger, et al from the mid 1990's.  

> I'd be interested in hearing others opinions on this topic, and
> whether this should be included in Ifeffit.

Corwin Booths approach to selfabsorption correction seems to be very 
nice. I think that especially its possibility to give up the "infinite 
sample thickness" limitation could be an important improvement over the 
previous approaches.
Still, it makes two (more or less implicit) assumptions:
* the detector surface has to be parallel to the x-ray beam (phi + theta 
= 90 deg)
* the detector has to have a neglectable solid angle

I'm not sure if these two assumptions hold for most fluorescence 
When I collected my last fluorescence data a couple of years ago, large 
solid angle detectors (like Lytle-detectors) were still in use. I have 
shown that Troegers approach to selfabsorption correction can be 
generalized for large detector surfaces (Phys. Rev. B 60, 9335 (1999)). 
In principle this should be also possible for Corwin Booths formula.
But when integrating over large solid angles, the exact geometry of the 
experimental setup plays a crucial role in determining the 
selfabsorption correction and I doubt that a useful implementation into 
iFeffit would be possible.

If, however, everyone is using solid state detectors now, I would say 
that implementing Corwin Booths code into iFeffit could be worth the effort.


Peter Pfalzer
Universitaet Augsburg                    Tel: +49-821-598-3215
Lehrstuhl fuer Experimentalphysik II     Fax: +49-821-598-3411
Universitaetsstr. 1
D-86135 Augsburg
Germany                   Peter.Pfalzer at physik.uni-augsburg.de

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