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

Frenkel, Anatoly frenkel at bnl.gov
Fri Dec 19 15:34:36 CST 2008


Dear Mengqiang,
 
To the best of my knowledge, in most cases Nitrogen cannot be discerned from Oxygen as a nearest neighbor since their scattering properties are similar. Thus, if you want to solve an "inverse" problem ("Which type of neighbors do I have") you cannot do it. However, if you believe you have some knowledge about the type of metal-oxygen bonding: either M=O or a M-O or a M-OH or a M-OH2 (the first one is the shortest and the strongest, the others may have similar interatomic distances but different bond strengths), you can advance somewhat.
 
If you have a certain number of distinct models you want to compare the data against, it can be done via a linear combination fitting, or by direct algebraic extraction of any given type of the pair contribution from the data, as described, for example here:
 
E. Poverenov, I. Efremenko, A. I. Frenkel, Y. Ben-David, L. J. W. Shimon, G. Leitus, J. M. L. Marin, D. Milstein. A terminal Pt(IV)-oxo complex bearing no stabilizing electron withdrawing ligands and exhibiting diverse reactivity. Nature 255, 1093-1096, 2008. 

See supplementary info to that article for specific details.
Regards,
Anatoly
 

________________________________

From: ifeffit-bounces at millenia.cars.aps.anl.gov on behalf of mzhu at udel.edu
Sent: Fri 12/19/2008 4:20 PM
To: ifeffit at millenia.cars.aps.anl.gov
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
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