amorphous metal alloys EXAFS spectra to be fitted with Artemis
Dear Sir or Madam, I got a normalized Fe K-edge EXAFS spectrum for my amorphous 7-component alloy sample, for which I know its atomic percent composition. I need to find out the interatomic distances between the Fe and the other atoms present in the alloy (identify the peaks in R-space) as well as how many atoms of each element is surrounding the absorbing iron atom (coordination number). To meet my goal, I think I need to fit the R-space Fourier transform of my EXAFS spectrum in a program like Artemis. Unfortunately, I haven`t found any tutorial discussing how to deal with amorphous sample with unknown organization of the atoms. When you are about to prepare an atomic model in Artemis for fitting, you need to build a model with an initial interatomic distances, atomic coordination number, etc, but all that is obviously unknown to me. I know nothing about the short range order in my material and I want to learn it from the experiment itself (note that itcan be and most probably is different from the one present in crystalline structures). So, my question is, could somebody tell me how to deal with such system using the Artemis, what type of initial models for fitting should be prepared? All of your help will be greatly appreciated. Best regards, Piotr Bardziński,
Hi Piotr,
On Aug 24, 2013 4:19 PM, Piotr J. Bardziński
Dear Sir or Madam,
I got a normalized Fe K-edge EXAFS spectrum for my amorphous 7-component
alloy sample, for which I know its atomic percent composition.
I need to find out the interatomic distances between the Fe and the other
atoms present in the alloy (identify the peaks in R-space) as well as how many atoms of each element is surrounding the absorbing iron atom (coordination number).
To meet my goal, I think I need to fit the R-space Fourier transform of
my EXAFS spectrum in a program like Artemis. Unfortunately, I haven`t found any tutorial discussing how to deal with amorphous sample with unknown organization of the atoms. When you are about to prepare an atomic model in Artemis for fitting, you need to build a model with an initial interatomic distances, atomic coordination number, etc, but all that is obviously unknown to me. I know nothing about the short range order in my material and I want to learn it from the experiment itself (note that it can be and most probably is different from the one present in crystalline structures). So, my question is, could somebody tell me how to deal with such system using the Artemis, what type of initial models for fitting should be prepared?
All of your help will be greatly appreciated.
Best regards, Piotr Bardziński,
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
If you really "know nothing" about the local structure around iron, you might be in for a challenging introduction to EXAFS analysis. You might actually have some idea about the local structure from the XANES, say for example if the iron is oxidized or is it still really in a metallic state. Even if only that, it is a place to start.... For EXAFS with artemis, you'll want to start with guesses of the local environment. They don't need to be good guesses, a suitable crystal structure will do, and you really only need to get the first shell distances close, because you'll refine these distances. You will probably need to do some real work in trying lots of candidate structures, but if you know it's a metallic glass, you probably actually know a little bit.... Cheers, --Matt
Hi Piotr, Matt wrote everything, but I have 2 small comments: - Fe environment if it is oxide or metallic state can be visible directly from the distance in most cases. - Piotr, you wrote nothing about composition (and detection method and preparation of the sample for the experiment) - only that you have 6 additional elements, what is stoichiometry and what kind of elements? This information can decrease the number of input parameters... Giving you advise knowing nothing about your sample is as a guesswork... Regards kicaj W dniu 13-08-24 23:18, "Piotr J. Bardziński" pisze:
Dear Sir or Madam,
I got a normalized Fe K-edge EXAFS spectrum for my amorphous 7-component alloy sample, for which I know its atomic percent composition.
I need to find out the interatomic distances between the Fe and the other atoms present in the alloy (identify the peaks in R-space) as well as how many atoms of each element is surrounding the absorbing iron atom (coordination number).
To meet my goal, I think I need to fit the R-space Fourier transform of my EXAFS spectrum in a program like Artemis. Unfortunately, I haven`t found any tutorial discussing how to deal with amorphous sample with unknown organization of the atoms. When you are about to prepare an atomic model in Artemis for fitting, you need to build a model with an initial interatomic distances, atomic coordination number, etc, but all that is obviously unknown to me. I know nothing about the short range order in my material and I want to learn it from the experiment itself (note that itcan be and most probably is different from the one present in crystalline structures). So, my question is, could somebody tell me how to deal with such system using the Artemis, what type of initial models for fitting should be prepared?
All of your help will be greatly appreciated.
Best regards, Piotr Bardziński,
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
participants (3)
-
"Dr. Dariusz A. Zając" -
"Piotr J. Bardziński" -
Matt Newville