[Ifeffit] Athena: k-weight=3 in background removal problem

[Joseph Washington]

Hi Carlo,
Since much of our data is located at high k values, it would be an 
improvement to be using a high k weight in the background removal. 
Whether or not this will be a vast improvement might be questionable. My 
main concern is why this occurs for all our Ge edge data  across the 
board, and if this is indicative of an underlying issue in data 
collection at the beamline or preprocessing.

Please see an attached project file containing some scans and a merge.

I appreciate the assistance,

Joseph

Carlo Segre wrote:
> 
> Hi Joseph:
> 
> On Mon, 7 Jul 2008, Joseph Washington wrote:
> 
>> Greetings all,
>> I am an APS user and a graduate of XAFS Summer School - class of 2007 :)
>>   We have been doing EXAFS analysis on Ge[2]Sb[2]Te[x] thin films. I
>> noticed that at the Ge edge in particular, the k-weight value used in
>> the background removal cannot equal 3, or else the background function
>> no longer follows the data and oscillates wildly and/or it shoots up at
>> the edge energy dominating the plot window. Values of 1 and 2 work fine.
>> Even more puzzling is that this problem is inherent for the Ge edge of
>> data taken over numerous runs, and for various samples (GST-224,
>> GST-225, 226, 227).
> 
> COuld you tell us why you would like to use a k-weight of 3 in the 
> background removal process?  I find that 1 (or 2 sometimes) is 
> sufficient to get a good result.  I just checked on a recent data set 
> and I agree that k-weight 1 nd 2 give nearly identical results but that 
> k-weight 3 for the same parameters is slightly different.
> 
> It would help a lot if you oculd send a project file for us to look at.
> 
> Carlo
> 

-- 
Joseph Washington
Research Assistant
Department of Physics
North Carolina State University
431 Riddick Hall
Raleigh, NC 27695-8202
email: jswashin at ncsu.edu
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