[Ifeffit] Need an advice
frenkel at bnl.gov
Fri May 6 16:12:14 CDT 2005
Re: [Ifeffit] Need an adviceLet me break the tie: here is what I just
received from one of the people cc'd to in Steven's email. This problem is
indeed even more complex than we all think.
The problem is even more complex:
- there is one Co2+ species in tetrahedral environment;
- there are small (20 - 100 atoms) metallic clusters;
- there is an intermediate Co+1 like species in tetrahedral coordination.
All these species may be present in some of the samples. Plus, I assume the
Co-O distance between Co in small metallic clusters and oxygen in the
silica is different than that between Co2+ ions and O2- ions in the cobalt
oxide - like compound, which adds to the complexety.
We feel like we're chasing our tail with this thing...:)
From: ifeffit-bounces at millenia.cars.aps.anl.gov
[mailto:ifeffit-bounces at millenia.cars.aps.anl.gov]On Behalf Of Scott Calvin
Sent: Friday, May 06, 2005 5:09 PM
To: XAFS Analysis using Ifeffit
Subject: Re: [Ifeffit] Need an advice
Hi Matt, The quote below is where I got the idea that Steven was
interested in size-determination of nanoparticles, but I may have
misunderstood...maybe he meant to use the fraction of oxide as a marker for
the surface to volume ratio? In any case, that still makes me think that he
expects to have nanoscale particles... --Scott Calvin Sarah Lawrence College
At 03:12 PM 5/5/2005 -0400, Steven wrote: >>>> However, if what we have is
closer to a physical mixture of small Co metal particles and Co oxide
particles, it would seem that it would be more appropriate to analyze
separately the windowed Co-O and Co-Co peaks in R-space, to somehow
normalize the Co-Co to the fraction of metal in the sample and use this as a
qualitative measure of metal particle size.
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