[Ifeffit] Self absorption or Ce4+ reduction in the CeO2 film?

[Weizi Yuan]

Dear all,
I have measured some spectra of a CeO2 film(~200nm) grown on Yittria
stablized Zirconia(YSZ) substrate under 2 conditions.
(i) room temperature, ambient atmosphere
(ii) room temperature, vacuum (pO2~1E-6 atm) inside a graphite dome of  the
DHS 1100 anton paar,
The spectra are collected in fluorescence mode. The incident angle is 3 o
 and the fluorescence collection angle is 90 o.

My questions are:
(i) From the theory behind the FLUO program developed Dr. Daniel Haskel,
CeO2 spectra collected with a 3 o incident angle *would have a strong self
absorption effect and need*

 correction , however, *the signal *is not attenuated compared with the
CeO2 powder taken in a transmission mode, shown in attached plot.
I've gone through many literature and people sometimes tell that whether
 they have a successful self absorption correction by comparing the
spectrum with a spectrum taken under a transmission mode.
So I'm wondering if I can say that I don't need a self absorption
correction in this case?
(ii)
The Ce4+ peak in the spectrum collected under condition (ii) has a much
lower intensity. I think it is due to the reduction of Ce 4+ under vacuum,
however, the Ce3+ peak does not show an increased signal here. Which makes
ma doubt whether this is simply reduction of Ce *or might be from over
absorption? *

Thanks for any response.

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