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

[Anatoly Frenkel]

Self absorption. 
There was a similar question a few weeks ago. 

Anatoly

Sent from my iPhone

> On Jun 22, 2017, at 11:11 AM, Weizi Yuan <weiziyuan2015 at u.northwestern.edu> wrote:
> 
> 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. 
> 
> <spectra.jpg> 
> -- 
> Regards,
> Weizi Yuan,
> Graduate Student,
> Northwestern University,
> Ph:(+1)312-560-9619
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