[Ifeffit] Self absorption in CeO2 spectrum

[Weizi Yuan]

Dear all,
I have measured some XANES spectra of CeO2 film(~220nm) in fluorescence
mode at Ce L3 edge with two incident angles of 0.6 degree and 3 degree. My
goal is to get relative surface sensitive (penetration depth~ 20 nm above
edge) information of [Ce3+] from 0.6 o  while bulk sensitive information at
3 o (penetration depth~ 160 nm above edge). In the meantime, I also
collected CeO2 powder reference spectrum under transmission mode. The
comparison is shown in the graph.
The film at 3 degree has a sharper white line than the powder while at 0.6
degree, it is the opposite. I think this might be because at the surface of
the film,it has more Ce3+ while when we detect the bulk it has more Ce4+.
My question  is how can I tell if I need self-absorption correction or not
for the films in this case? Can I say I do not need self absorption
correction because I have a higher normalized u for the film collected in
the fluorescence mode than powder collected in the transmission mode?
Thanks a lot for your comments.
Weizi
[image: Inline image 1]


-- 
Regards,
Weizi Yuan,
Graduate Student,
Northwestern University,
Ph:(+1)312-560-9619
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