This is not quite accurate: the coordination number measured by EXAFS is the TOTAL number of closest neighbors per TOTAL number of absorbing atoms. If the sample is a single phase, these two definitions are the same. If the sample is heterogeneous, e.g., some percentage x of nanoparticles and the rest (1-x) percent - low molecular weight complexes of the same metal, EXAFS will measure coord. number of metal-metal bonds to be much lower than you expect in the particle of a given size and structure. The scaling factor can be found here: http://pubweb.bnl.gov/users/frenkel/www/Pd-SUNY/pd-suny.pdf Anatoly -----Original Message----- From: ifeffit-bounces@millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov]On Behalf Of Stefano Ciurli Sent: Thursday, November 23, 2006 1:38 PM To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] Coordination number Hi Juan, I am not sure why you say that the question is polemic. I will give you the definition that a coordination chemist would give: the coordination number is the number of closest neighbours. But maybe I do not understand the question Regards Stefano
I have a simple question but I am afraid it is polemic. Why people always calculate coordination numbers and bond distances and how? I have an e-mail where Bruce described perfectly how to calculate the coordiantion number for the first shell. But,...if I have bimetallic catalysts or/and a mixture of structures with several close paths (similar Reff), then coordination number is an average number? I am not very sure how to calculate them in Artemis with SO2 and standards.
Thank you very much
Best regards, JA
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-- ____________________________________________ Stefano Ciurli Professor of Chemistry Laboratory of Bioinorganic Chemistry Department of Agro-Environmental Science and Technology University of Bologna Viale Giuseppe Fanin, 40 I-40127 Bologna Italy Phone: +39-051-209-6204 Fax: +39-051-209-6203 "Fatti non foste a viver come bruti, ma per seguir virtute e canoscenza" Dante Alighieri - Inferno - Canto XXVI "Ihr seid bestimmt, nicht Tieren gleich zu leben, Nein, Tugend zu erringen und Erkenntnis" "Ye were not form'd to live the life of brutes, But virtue to pursue and knowledge high" _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit