Dear Rana,
yes, it will have effects on your XAFS spectra, but not really
destructive. EXAFS only really vanishes if you have isolated atoms. As
long as your particles still have several hundred atoms with some
coordination shell-like ordering, EXAFS oscillations will show up.
However, the amplitude of the XAFS signals will be smaller than in bulk
material, due to the lower average coordination number of the central
atoms. If you e.g. have 5 nm particles (some 2000 atoms), already almost
half of the atoms (~800) is sitting on the particle surface and
therefore has a reduced coordination number.
There's a wealth of information in literature where people actually use
this effect for determining the particle size from XAFS.
Another thing to keep in mind is that often it's not really clear how
the surfaces of a particle looks like chemically - there might be
adsorbates, or even passivation layers. If you're e.g. doing EXAFS on
untreated 5nm Si particles, you can't really expect to see anything
close to bulk Si, because the top layer might be SiO2
Best regards,
Dominik
On 07.06.2010 14:49, Jatinkumar Rana wrote:
Dear Users,
I am working with the EXAFS technique for the characterization of my
powder sample. I must admit that i am very much new to the technique and
its analysis. I have read many tutorials on preparing sample for XAFS
measurement (both transmission and fluoroscence). However, i am dealing
with the powder having particle size much more smaller than one
absorption length.
I would like to know will it create any destructive effect on my XAFS
spectra ??
Many thanks in advance...
Warm wishes,
Rana
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Dr. Dominik Samuelis
[email protected]
Max-Planck-Institut für Festkörperforschung
Max Planck Institute for Solid State Research
Heisenbergstr. 1
70569 Stuttgart
Germany
Phone +49-711-689-1769
Fax +49-711-689-1722
Web http://www.fkf.mpg.de/maier/
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