Re: [Ifeffit] Normalization of XANES spectra

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 ifeffit-request@millenia.cars.aps.anl.gov schrieb:

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Today's Topics:

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 Subject: [Ifeffit] Normalization of XANES spectra To: ifeffit@millenia.cars.aps.anl.gov Message-ID: <49086D0E.2000603@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