[Ifeffit] UO2 thin films on STO

[Maxim Boyanov]

Mohamed,

 

The answer to that would depend on the relative amounts of U and Sr that you
probe simultaneously with the beam, as well as what you mean by
"interference". By 1000 eV above the edge oscillations from the EXAFS are
largely gone (relative to the edge step). So I would say that Sr K-edge
oscillations are unlikely to interfere with your U L-edge oscillations,
unless your U L-edge step is say 500x smaller than your Sr edge step or the
Sr atoms are in a very tight binding environment (not sure if STO qualifies)
and you decide to measure the spectra at LN temperature.  Your bigger
problem will likely be collecting the U EXAFS data with sufficient
signal-to-background ratio. Attached is an XRF spectrum from a
U-contaminated sediment containing Sr (not sure what the Sr:U ratio is, but
I think it is small), measured in a relatively high energy resolution mode
of a Ge detector. You can imagine the Sr line being many many times bigger
in your system, so the U line may end up being a small blip on the left
shoulder of the Sr line. A solid state detector will probably not be able to
sufficiently separate the two signals. You may have to use grazing incidence
geometry to minimize the substrate Sr signal and/or use a high energy
resolution detector to separate the U and Sr lines (e..g a bent Laue
analyzer). Both of the latter will make the experiment non-trivial, so be
prepared for some extra work :-). 

 

Finally, the answer will depend on the level of detail you are hoping to get
from the measurement. If all you are interested in is proving the formation
of uraninite then the U-U coordination should be relatively easy to see in a
Fourier transform in spite of all the possible "interference" effects
discussed above.

 

Cheers,

Max.

 

  _____  

From: ifeffit-bounces at millenia.cars.aps.anl.gov
[mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf Of mohamed
sobhy
Sent: Tuesday, November 16, 2010 3:38 PM
To: ifeffit at millenia.cars.aps.anl.gov
Subject: [Ifeffit] UO2 thin films on STO

 

Dear All
I would like to grow UO2 thin films on STO (SrTiO3) substrate but I found
that Sr K-edge 16105 and U L3-edge is 17166. Do you think there will be any
interference?
Best,

Mohamed

 

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