Re: [Ifeffit] How to identify N and O atoms in the first coordinate

Hello JeongEunSuk, Following your recommendation, I do find the pre-edge peak corresponding to s->d electron transition slightly shifts to higher energy for a nickel nitrogen-coordinated organic reference than for a nickel oxygen-coordinated organic reference. But the peak position is nearly the same for the nitrogen-coordinated organic reference with the aqueous nickel solution. I guess it is because the long Ni-OH2 bond in the aqueous nickel solution which also results in a less electron density on nickel(higher oxidation state). I will think about that. Thanks for your recommendations. Best wishes, Mengqiang Zhu ----------------------- Mengqiang Zhu Ph.D Candidate Environmental Soil Chemistry Department of Plant and Soil Sciences University of Delaware 152 Townsend Hall Newark, DE 19716 http://ag.udel.edu/soilchem/zhu.html ---- Original message ----

Date: Sat, 20 Dec 2008 16:02:44 +0900 From: ifeffit-bounces@millenia.cars.aps.anl.gov (on behalf of JeongEunSuk ) Subject: Re: [Ifeffit] How to identify N and O atoms in the first coordinate To: ifeffit

Hello mzhu

I think that it is impossible to distinguish nitrogen with oxygen by using EXAFS. I would like to recommend XANES for your study. The shift of pre-edge of XANES shows how the oxidation state of metal is changed. As you know, If there are nitrogen atoms in substitute for oxygen atoms around metal, the pre-edge of metal xanes may shift to high energy because the oxidation state increases.

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From: mzhu@udel.edu To: ifeffit@millenia.cars.aps.anl.gov Date: Fri, 19 Dec 2008 16:20:39 -0500 Subject: [Ifeffit] How to identify N and O atoms in the first coordinate

Hello all, Merry Christmas! I have some samples of heavy metal sorption on bacterial biofilm. I want to figure out what elements are coordinated with the heavy metal in the first coordinate. Since the oxygen and nitrogen have similar scattering factors, how can I differetiate them? Using shell-by-shell fitting or linear combination fitting with standards? Thanks.

Best wishes,

Mengqiang Zhu

----------------------- Mengqiang Zhu Ph.D Candidate Environmental Soil Chemistry Department of Plant and Soil Sciences University of Delaware 152 Townsend Hall Newark, DE 19716 ! http://ag.udel.edu/soilchem/zhu.html _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov

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