[Ifeffit] Normalization of XANES spectra

[Jens Kruse]

Thanks for your replay and sorry for the confusing question. but I think it not getting better.

Scott, you are right LCF would be helpful but even with lot of standards it is hard to get a meaningful result from low concentrated samples at the N k-edge. 
I think my problem is than I don`t understand the physical meaning of a edge step normalized spectra. Is it the spectrum 1 x-ray photon would produce? Is it right that I loose the information of the absolute concentration after normalization so that I still can identify relative proportions of different compounds with in a sample but I can`t compare different spectra in an absolute way anymore? The extreme case would be a comparison of pure and a diluted spectra.  

jens
 







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> Today's Topics:
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>    1. Normalization of XANES spectra (Jens Kruse)
>    2. Re: Normalization of XANES spectra (Frenkel, Anatoly)
>    3. Re: Normalization of XANES spectra (Scott Calvin)
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> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 29 Oct 2008 15:02:54 +0100
> From: Jens Kruse <jens.kruse at uni-rostock.de>
> Subject: [Ifeffit] Normalization of XANES spectra
> To: ifeffit at millenia.cars.aps.anl.gov
> Message-ID: <49086D0E.2000603 at uni-rostock.de>
> Content-Type: text/plain; charset="ISO-8859-15"; format=flowed
>
> Hi everyone,
>
> I have a general question:
> I know Normalizing is something we do so that we can compare samples 
> measured
> under different experimental conditions (removes the effect of different 
> gains ...) but I have problems in understanding and applying 
> normalization when also quantitative conclusions are needed when 
> comparing different spectra.
>
> If I have two XANES spectra (a) and (b) measure under the same 
> conditions but with different concentration of the absorbing atom with 
> in different molecules.If both normalized spectra show a peak 1 , but 
> this peak is higher in intensity in spectrum (a) than in spectrum (b), 
> does this mean that compound which produced peak 1 is also absolute 
> higher in concentration in sample/spectrum (a) or do I loose this 
> information after normalization?
> Or can I just say: in the normalized spectrum (a) peak 1 is higher than 
> peak 2 suggesting that the compound leading to peak 1 is more abundant 
> (just relative proportions).But I can't say: The intensity of peak 1 in 
> the also normalized spectrum 2 is lower than in spectrum one, Therefore, 
> the compound leading to peak 1 is less abundant in spectrum/sample 2. ????
>
>
> I hope somebody can help me to understand this issue.
>
> Thanks a lot,
>
> 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