Re: [Ifeffit] Ifeffit Digest, Vol 171, Issue 14
Got it. Thanks for the response, Anatoly. Weizi On Fri, May 19, 2017 at 4:37 PM, wrote: > Send Ifeffit mailing list submissions to > ifeffit@millenia.cars.aps.anl.gov > > To subscribe or unsubscribe via the World Wide Web, visit > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > or, via email, send a message with subject or body 'help' to > ifeffit-requ...@millenia.cars.aps.anl.gov > > You can reach the person managing the list at > ifeffit-ow...@millenia.cars.aps.anl.gov > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Ifeffit digest..." > > > Today's Topics: > >1. Self absorption in CeO2 spectrum (Weizi Yuan) > > > -- > > Message: 1 > Date: Fri, 19 May 2017 16:37:54 -0500 > From: Weizi Yuan > To: ifeffit@millenia.cars.aps.anl.gov > Subject: [Ifeffit] Self absorption in CeO2 spectrum > Message-ID: > inz...@mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > 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 > -- next part -- > An HTML attachment was scrubbed... > URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/ > attachments/20170519/329bcb58/attachment.html> > -- next part -- > A non-text attachment was scrubbed... > Name: CeO2.png > Type: image/png > Size: 28979 bytes > Desc: not available > URL: <http://millenia.cars.aps.anl.gov/pipermail/ifeffit/ > attachments/20170519/329bcb58/attachment.png> > > -- > > Subject: Digest Footer > > ___ > 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 > > > -- > > End of Ifeffit Digest, Vol 171, Issue 14 > > -- 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
Re: [Ifeffit] Self absorption in CeO2 spectrum
It is all self-absorption (over-absorption) that explains the difference. Ce 3+ will appear as a separate shoulder below the first peak and there is no evidence of this contribution in the spectra. These effects, including the difference between the spectra of the powder and film CeO2 due to self-absorption, are extensively described in literature. Anatoly Sent from my iPhone > On May 19, 2017, at 5:37 PM, Weizi Yuan > wrote: > > 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 > > > > -- > 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 ___ 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
[Ifeffit] Self absorption in CeO2 spectrum
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 ___ 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
