[Ifeffit] consultation

[Welter, Edmund]

Dear Mingliang,

simply because Athena is not normalising the height of the highest peak 
(the white line) but the EXAFS region, that is it starts some 10 eV 
above the edge. You choose the normalisation region in Athenas settings. 
  You can see in your plots that it does this job quite well, the 
spectra oscillate around 1 (at E > E0+40 eV).

Anyway, take care what you do when you try to fit a fluorescence yield 
XAFS spectrum with references which were measured in transmission mode. 
You must at least be sure that you considered the "self absorption 
effect" which dampens the oscillations (most notably the large 
oscillations in the XANES region). The importance of this effect depends 
on your sample's composition.

Athena contains functions to correct the self absorption. In order to do 
this you need the elemental composition of your sample and the angles 
between sample, incoming beam and detector.

Best regards,
Edmund Welter

¿µÃ÷ÁÁ wrote:
> Dear,
> I want to to ask a question about using Linear Combination Fitting in 
> Athena. I normalized all the references(measured in transmission mode) 
> and samples (fuorescence mode) with Athena, and then wish to use LCF to 
> quantify each unique component in the samples. But I noted that the 
> normalized samples spectra had lower height at the white line peak than 
> any references(shown pic-1.emf in annex), thus the fitted spectra 
> were also higher than the original sample spectra (shown pic-2 and 
> -3.emf in annex). I do not know why? I also attached all the original 
> data(before normalization). Wish to obtain guidance from you. Thanks!
> Best wishes
> Mingliang
> 
> 
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