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

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 _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit