Re: [Ifeffit] lifetime broadening of pre-edge peaks
How significant are the photoelectron effects in hard X-rays compared with the core-hole effect? What I'm really after is a criterion for determining, at least roughly, how narrow a real, physical feature can be. mam - Original Message - From: vik...@comcast.net To: ifeffit@millenia.cars.aps.anl.gov Sent: Monday, October 10, 2011 6:37 PM Subject: Re: [Ifeffit] lifetime broadening of pre-edge peaks Hi Matthew, The lifetime broadening of the XANES features is determined by the time of life of the final excited state. This two-particle excitation includes the core hole and the photoelectron. The core hole may decay due to the various radiation or non radiation processes. The photoelectron state may decay due to inelastic collisions, plasmon excitations, etc. The time of life of the core hole, I believe, does not depend on the photon energy whilst the last is near the absorption edge. But it is not true for the photoelectron. It is better to write “photoelectron” because some of the pre-edge peaks which exist in the transition metal oxides spectra are in fact X-ray excitons and no photoemission can be observed. In these cases the final states are bound states and it is purely many electron effect caused by the core-hole - “photoelectron” interaction. For those pre-edge peaks the life time broadening is determined entirely by the core-hole life time. But as soon as photoelectron jumps to the conduction band the mechanisms of its inelastic scattering turn on and one should take into account the time of life of photoelectron (now without quotes). Unfortunately, it is difficult to determine which pre-edge peaks are excitonic and which are not. As it was already mentioned there are other mechanisms of broadening of the pre-edge peaks. For diamagnetic atoms it is thermal vibrations, for paramagnetic ones it is multiplet interactions as well. Good luck. Victor Krayzman. -- ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Re: [Ifeffit] lifetime broadening of pre-edge peaks?
Dear Matthew you can find examples of determination of life-time broadening, deconvolution of XANES specra, and discussion about limitations due to noise in several papers, for example: A. Filipponi, J. Phys. B 33, 2835 (2000) * A. Kodre, I. Arčon, J. Padeznik Gomilšek, R. Frahm*// J. Phys. B: At. Mol. Opt. Phys. 35 (2002) 3497-3513 *A. Kodre, J. Padežnik Gomilšek, A. Mihelič, I. Arcon*/ /Radiation Physics and Chemistry 75 (2006) 188-194 *J. Padeznik Gomilsek, I. Arcon, S. de Panfilis, A. Kodre,* / /Phys. Rev. A 79, (2009) 032514, regards Iztok Matthew Marcus wrote: Is the core-hole lifetime broadening of pre-edge XANES peaks the same as at the main edge? I'm looking into issues of de-noising of XANES epsctra, so need to figure out how narrow real features can be. mam ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit -- prof. dr. Iztok Arcon University of Nova Gorica Vipavska 13, POB 301 5001 Nova Gorica, Slovenia tel: +386 5 331 5227 fax: +386 5 331 5240 e-mail: iztok.ar...@ung.si http://www.ung.si/~arcon http://www.ung.si/~arcon/xas ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Re: [Ifeffit] lifetime broadening of pre-edge peaks?
Thanks. While none of these have to do with pre-edge peaks such as are found in transition-metal oxides, the assumption of constancy of core-hole broadening does seem to work. mam - Original Message - From: Iztok Arčon To: XAFS Analysis using Ifeffit Sent: Monday, October 10, 2011 12:32 AM Subject: Re: [Ifeffit] lifetime broadening of pre-edge peaks? Dear Matthew you can find examples of determination of life-time broadening, deconvolution of XANES specra, and discussion about limitations due to noise in several papers, for example: A. Filipponi, J. Phys. B 33, 2835 (2000) A. Kodre, I. Arčon, J. Padeznik Gomilšek, R. Frahm J. Phys. B: At. Mol. Opt. Phys. 35 (2002) 3497-3513 A. Kodre, J. Padežnik Gomilšek, A. Mihelič, I. Arcon Radiation Physics and Chemistry 75 (2006) 188-194 J. Padeznik Gomilsek, I. Arcon, S. de Panfilis, A. Kodre, Phys. Rev. A 79, (2009) 032514, regards Iztok Matthew Marcus wrote: Is the core-hole lifetime broadening of pre-edge XANES peaks the same as at the main edge? I'm looking into issues of de-noising of XANES epsctra, so need to figure out how narrow real features can be. mam ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit -- prof. dr. Iztok Arcon University of Nova Gorica Vipavska 13, POB 301 5001 Nova Gorica, Slovenia tel: +386 5 331 5227 fax: +386 5 331 5240 e-mail: iztok.ar...@ung.si http://www.ung.si/~arcon http://www.ung.si/~arcon/xas -- ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
Re: [Ifeffit] lifetime broadening of pre-edge peaks?
I think experimental answer could be the simplest one. Perhaps there is anyone on the list who measured low concentrations of low Z absorber in the high Z host at both edges? For example, Cu in Ag (if does dissolve in Ag if made by rapid quenching) at Cu K-edge, and Ag K-edge (or just bulk Ag since the data will be the same). These should be solid solutions, of course. Then, despite the difference in phase shift, the EXAFS oscillations should be comparable in magnitude if the broadening is not significant, and it should be more intense for the Cu K-edge if the broadening at Ag K edge is significant. Another option: to hear from people doing HERFD. That is normally done on XANES, for the reason, I assume, that they do not see any advantage in EXAFS region, where broadening does not change compared to total fluorescence. I think the explanation that EXAFS should not be too sensitive to the life time broadening is that EXAFS originates from the final state interference, while the XANES - from both the final state interference and DOS. But may be experiments are showing the opposite, and that will prove me wrong. Anatoly From: ifeffit-boun...@millenia.cars.aps.anl.gov [ifeffit-boun...@millenia.cars.aps.anl.gov] on behalf of Matthew Marcus [mamar...@lbl.gov] Sent: Monday, October 10, 2011 2:23 PM To: XAFS Analysis using Ifeffit Subject: Re: [Ifeffit] lifetime broadening of pre-edge peaks? Thanks. While none of these have to do with pre-edge peaks such as are found in transition-metal oxides, the assumption of constancy of core-hole broadening does seem to work. mam - Original Message - From: Iztok Arčonmailto:iztok.ar...@ung.si To: XAFS Analysis using Ifeffitmailto:ifeffit@millenia.cars.aps.anl.gov Sent: Monday, October 10, 2011 12:32 AM Subject: Re: [Ifeffit] lifetime broadening of pre-edge peaks? Dear Matthew you can find examples of determination of life-time broadening, deconvolution of XANES specra, and discussion about limitations due to noise in several papers, for example: A. Filipponi, J. Phys. B 33, 2835 (2000) A. Kodre, I. Arčon, J. Padeznik Gomilšek, R. Frahm J. Phys. B: At. Mol. Opt. Phys. 35 (2002) 3497-3513 A. Kodre, J. Padežnik Gomilšek, A. Mihelič, I. Arcon Radiation Physics and Chemistry 75 (2006) 188-194 J. Padeznik Gomilsek, I. Arcon, S. de Panfilis, A. Kodre, Phys. Rev. A 79, (2009) 032514, regards Iztok Matthew Marcus wrote: Is the core-hole lifetime broadening of pre-edge XANES peaks the same as at the main edge? I'm looking into issues of de-noising of XANES epsctra, so need to figure out how narrow real features can be. mam ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.govmailto:Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit -- prof. dr. Iztok Arcon University of Nova Gorica Vipavska 13, POB 301 5001 Nova Gorica, Slovenia tel: +386 5 331 5227 fax: +386 5 331 5240 e-mail: iztok.ar...@ung.simailto:iztok.ar...@ung.si http://www.ung.si/~arcon http://www.ung.si/~arcon/xas ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
[Ifeffit] lifetime broadening of pre-edge peaks?
Is the core-hole lifetime broadening of pre-edge XANES peaks the same as at the main edge? I'm looking into issues of de-noising of XANES epsctra, so need to figure out how narrow real features can be. mam ___ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit
