[Ifeffit] EXAFS fitting method

["Dr. Dariusz A. Zając"]

  Hi Abhijeet,
not in all cases you can get (or get full) crystal structure from 
database. Then, additional EXAFS experiments can be helpful. Of course,  
you can also imagine more situation, as doping, vacancies or 
substitutions, etc. You can also try to create crystal model without XRD 
data.
Please, do not forget that EXAFS is the element selective method, and 
probes the structure locally.
Answering the third question - if you have EXAFS data, and model of 
crystallographic structure you can compare both, and if it is needed 
adjust/model the structure to get better agreement. If you use know 
structure from another compound you should be sure that you have 
replaced elements according to elements, ocupancy and positions in your 
sample.
regards
kicaj

W dniu 11-01-30 09:23, Abhijeet Gaur pisze:
> Hi all,
>           As I understand, the EXAFS fitting procedure using Artemis, 
> for generating a theoretical model requires the crystal structure 
> parameter like space group, cell parameters and _specially_ _atom 
> coordinates_ etc.  For this we have to perform XRD measurements of 
> single crystals of the samples. I have some questions
> (1) In case we dont have the XRD data of a sample then how can the EXAFS
>       analysis be done  of that sample?
> (2) If we have already performed the XRD on the sample then by doing
>      EXAFS what additional information are we getting ?
> (3) If the answer to the first question is that - *use the crystal 
> structure of a *
> *      similar sample,* then what are the conditions under which we 
> can use the
>       known crystal structure of one sample for other samples ?
> Thanks in advance
> Abhijeet Gaur
>
>
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