[Ifeffit] status of self-absorption corrections

[Matt Newville]

Hi Mauro, 

I haven't done anything about self-absorption corrections besides
read a few of the papers and look at Booth's and Haskel's code and
docs.  Your assessment that there was 'no conclusion' from the
previous discussions seems correct to me.

I believe SixPack has incorporated Booth's algorithm already, so
perhaps Sam or someone who has used this in SixPack can comment on
it.  Booth's and Haskel's programs are available, of course.

I'd prefer to have a single procedure that could correct both XANES
and EXAFS, and took into account sample thickness, incident angle
and the range of exit angles as separate parameters.  It seems that
enough people have published partial solutions that it could be done
'right'.  I was hoping someone would come up with something more
definitive.  It seems like a good project for a student.

For what it's worth, if you're using a Ge detector, the deadtime 
corrections might also be important. 

--Matt

On Fri, 30 Apr 2004 mauro at rulp.org wrote:

> Hi to all,
> 
> I would like to ask you which is the status of the discussion on the
> self-absorption corrections to fluorescence EXAFS.
> 
> I'm working on Mo/Si multilayers, studied by standing-wave-assisted EXAFS.
> My data are collected at grazing incidence (phi + theta = 90 deg) with a Ge
> (13 elements) detector. I have done data analysis without self-absorption
> corrections and I have found good results, except for the amplitude (S_0^2)
> that is very low (~0.50). I think this low value is due to self-absorption,
> so I would like to demonstrate it.
> 
> My dilemma is: Troger's approach or Booth's one?
> 
> I personally think that Booth's (simple) approach, could be used in this
> particular case (Ge detector, phi+theta=90deg), but my tutor told me that I
> can't assume a neglectable solid angle for a Ge detector so I have to use
> the Troeger's (quite difficult) approach. 
> 
> >From the mailing-list archive, I have read your discussion about this topic
> but I haven't found something like a "conclusion". Is there anyone who use
> Booth's approach with good results? Have you already done "tests" of this
> method? Is it possible to improve it?
> 
> Finally, what about the software status? Matt, have you done something on
> Booth's Fortran code?
> 
> Thanks,
> Mauro
> 
> --
>   Mauro Rovezzi <mauro at rulp.org> - Physics student
>   University of Rome "Tor Vergata", ESRF Beamline BM8 - GILDA 
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