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