Hi all, I wonder if it is possible from XANES unusual data treatment to get information such as number and distances of neigbhors in the first and second shells. I think that could be very interesting for low Z elements such as P, S, Ca, K, Al, etc in diluted samples. Thanks in advance. Marcelo.
Hi Marcelo,
First and 2nd neighbor distances are usually modeled using EXAFS data in ARTEMIS. XANES might give you information about the coordination if you have some reference data to compare.
More information or detail about your experiment might get you a better answer,
thanks,
Chris
********************************************
Dr. Christopher Patridge
Assistant Professor of Chemistry
Dept of Math and Natural Science
D'youville College
320 Porter Ave., Buffalo, NY 14201
Phone: 716-829-8096
Email: patridgc@dyc.edu
On Jan 16, 2015, at 10:21 AM, Marcelo Alves
Hi all,
I wonder if it is possible from XANES unusual data treatment to get information such as number and distances of neigbhors in the first and second shells.
I think that could be very interesting for low Z elements such as P, S, Ca, K, Al, etc in diluted samples.
Thanks in advance.
Marcelo. _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
On Fri, Jan 16, 2015 at 9:21 AM, Marcelo Alves
Hi all,
I wonder if it is possible from XANES unusual data treatment to get information such as number and distances of neigbhors in the first and second shells.
There is an old-ish (like, from the 1950's I think) and fairly heuristic rule that the XANES edge energy shifts scale as 1/R^2 for the nearest neighbor. I think that Grant Bunker has a nice set of slides showing this, somewhere on the web. For example, I think this explains well slight energy shifts in the peak energy of the sulfate resonance. My recollection is that it works pretty well for many well-constrained set of spectra, but isn't quite as quantitative and readily applicable to unknown systems as one might hope. It's also sort of related to the idea of bond-valence that, for a given class of systems (say, oxides of a particular metal), R, N, and formal valence state are not independent quantities. --Matt
There is also Smolentsev and Soldatov's work using FitIT as well as FDMNES and FEFF G. Smolentsev and A.V. Soldatov "FitIt: new software to extract structural information on the basis of XANES fitting http://dx.doi.org/10.1016/j.commatsci.2006.08.007" Comp. Matter. Science 39 (2007) 569. http://journals.aps.org/prb/abstract/10.1103/PhysRevB.75.144106 http://www.nano.sfedu.ru/fitit.html Though I haven't tried it myself, Grigory did give an interesting talk on to the APS XAFS community some years ago. On 1/16/2015 9:53 AM, Matt Newville wrote:
On Fri, Jan 16, 2015 at 9:21 AM, Marcelo Alves
mailto:mealves@gmail.com> wrote: Hi all,
I wonder if it is possible from XANES unusual data treatment to get information such as number and distances of neigbhors in the first and second shells.
There is an old-ish (like, from the 1950's I think) and fairly heuristic rule that the XANES edge energy shifts scale as 1/R^2 for the nearest neighbor. I think that Grant Bunker has a nice set of slides showing this, somewhere on the web. For example, I think this explains well slight energy shifts in the peak energy of the sulfate resonance. My recollection is that it works pretty well for many well-constrained set of spectra, but isn't quite as quantitative and readily applicable to unknown systems as one might hope.
It's also sort of related to the idea of bond-valence that, for a given class of systems (say, oxides of a particular metal), R, N, and formal valence state are not independent quantities.
--Matt
_______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
-- Dr. Robert Gordon Staff Scientist, CLS@APS APS Sector 20 (CLS/XSD) 9700 S. Cass Ave. 435E Argonne, IL USA 60430 ph/fx 630-252-0581/0580
The MXAN package (https://www.lnf.infn.it/theory/CondensedMatter/mxan.html and http://www.esrf.eu/computing/scientific/MXAN/) does something along the lines of what you are interested in, in terms of giving a realistic physical model rather than merely fingerprinting. However, it is computationally intensive and isn't too beginner-friendly.
Erik
On Friday, January 16, 2015 10:22 AM, Marcelo Alves
participants (5)
-
Christopher Patridge
-
Erik Farquhar
-
Marcelo Alves
-
Matt Newville
-
Robert Gordon