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Re: [Ifeffit] Your internet exchange with "Chachi" about FeCo, last year
by Dominik Samuelis 31 Oct '08

31 Oct '08

Dear Dr. English, unfortunately, I am not a metals and intermetallics expert. I mostly work on oxides and related phases. Nevertheless, I've now ordered your original TMS paper from our library. As soon as I've found the time to read your analysis, I'll get in touch with you. There might be a good chance that EXAFS could give additional insight into these fine domain structures, since - as you wrote - many atoms will have a large number of wrong next neighbors. Maybe, there are also some intermetallics experts on this list, who could comment on this more knowledgeably. Best regards, Dominik Samuelis > Dear Sir: I just ran across your exchange of ideas on FeCo order etc. > about this time last year. I did some experiments in the mid 60s > (Trans. Met. Soc AIME 236 (1966) 14ff.) on FeCo2V and showed that the > superlattice xray line [100} can be seen in brine-quenched thin strips > if the XRD is done with CoKa radiation. The lines are very broad in > as-quenched state and the peak narrows gradually with time of > reheating to a few hundred degrees C. > The interpretation was that we were seeing APB domains which were > unexpected but seemed obvious in hindsight--two interpenetrating, > multiply-connected domains sort of like "swiss cheese" (J. W. Cahn > called it "sponge" at the time--he wrote an elegant mathematical > analysis that appeared in Acta Met.). The "scale" of interconnection > changes with time at temperature as the structure coarsens to reduce > the energy associated with APB. I thought the picture was confusing > since "perfect order with very fine domain size" could as well be > descri bed as partial, or incomplete order due to large number of > wrong near neighbors. I don't know if there are other alloys or > chemical combinations in which B2 order is present with very fine > domain structure such as I described. I am not aware of any other work > that confirmed or reinterpreted my results. Any comments? -- Dr. Dominik Samuelis d.samuelis(a)fkf.mpg.de Max-Planck-Institut für Festkörperforschung Heisenbergstr. 1 70569 Stuttgart Germany Phone +49-711-689-1769 Fax +49-711-689-1722 Web http://www.fkf.mpg.de/maier/

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Re: [Ifeffit] Ifeffit Digest, Vol 68, Issue 29
by daesung 30 Oct '08

30 Oct '08

Dear J. Rehr, it is an interesting issue for me. I thought that FEFF calculates for L2 and L3 absorption edges if I use EDGE L3 card, since they overlap in a small energy region. Now I understand why I had bad results for L23 edge calculations. However, where can I find scripts for adding FEFF results for two edges? Are they somewhere in FEFF 8 documents? Please give me more informations Daesung Park On Thursday 30 October 2008 18:00:01 ifeffit-request(a)millenia.cars.aps.anl.gov wrote: > Send Ifeffit mailing list submissions to > ifeffit(a)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-request(a)millenia.cars.aps.anl.gov > > You can reach the person managing the list at > ifeffit-owner(a)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. Fe_L2L3 (Guvenc Akgul (gakgul)) > 2. Re: Fe_L2L3 (John J. Rehr) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 29 Oct 2008 16:17:10 -0500 > From: "Guvenc Akgul (gakgul)" <gakgul(a)aps.anl.gov> > Subject: [Ifeffit] Fe_L2L3 > To: ifeffit(a)millenia.cars.aps.anl.gov > Message-ID: <fb33bc484270.49088c86(a)aps.anl.gov> > Content-Type: text/plain; charset=us-ascii > > dear all, > > I have to calculate L3 and L2 absorption edges for pure Fe as theorical > .how can I do this using FEFF? > > thanks > > guven > > > ------------------------------ > > Message: 2 > Date: Wed, 29 Oct 2008 20:03:51 -0700 (PDT) > From: "John J. Rehr" <jjr(a)phys.washington.edu> > Subject: Re: [Ifeffit] Fe_L2L3 > To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> > Message-ID: > <Pine.LNX.4.64.0810292003250.16641(a)donatello.phys.washington.edu> > Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed > > Subject: Re: [Ifeffit] Fe_L2L3 > > Dear Guvenc, > > It's pretty easy, but you have to do the calculation edge by edge and > then add, i.e., two calculations, one with > > EDGE L3 > > and one with > > EDGE L2 > > The FEFF project has scripts for adding FEFF results for two edges - send > email to jjr(a)phys.washington.edu for details. > > J. Rehr > > On Wed, 29 Oct 2008, Guvenc Akgul (gakgul) wrote: > > dear all, > > > > I have to calculate L3 and L2 absorption edges for pure Fe as theorical > > .how can I do this using FEFF? > > > > thanks > > > > guven > > _______________________________________________ > > Ifeffit mailing list > > Ifeffit(a)millenia.cars.aps.anl.gov > > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > > ------------------------------ > > _______________________________________________ > Ifeffit mailing list > Ifeffit(a)millenia.cars.aps.anl.gov > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > > > End of Ifeffit Digest, Vol 68, Issue 29 > ***************************************

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Re: [Ifeffit] Fe_L2L3
by John J. Rehr 29 Oct '08

29 Oct '08

Subject: Re: [Ifeffit] Fe_L2L3 Dear Guvenc, It's pretty easy, but you have to do the calculation edge by edge and then add, i.e., two calculations, one with EDGE L3 and one with EDGE L2 The FEFF project has scripts for adding FEFF results for two edges - send email to jjr(a)phys.washington.edu for details. J. Rehr On Wed, 29 Oct 2008, Guvenc Akgul (gakgul) wrote: > dear all, > > I have to calculate L3 and L2 absorption edges for pure Fe as theorical .how > can I do this using FEFF? > > thanks > > guven > _______________________________________________ > Ifeffit mailing list > Ifeffit(a)millenia.cars.aps.anl.gov > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit >

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Fe_L2L3
by Guvenc Akgul (gakgul) 29 Oct '08

29 Oct '08

dear all, I have to calculate L3 and L2 absorption edges for pure Fe as theorical .how can I do this using FEFF? thanks guven

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Re: [Ifeffit] Normalization of XANES spectra
by Jens Kruse 29 Oct '08

29 Oct '08

Thanks for your replay and sorry for the confusing question. but I think it not getting better. Scott, you are right LCF would be helpful but even with lot of standards it is hard to get a meaningful result from low concentrated samples at the N k-edge. I think my problem is than I don`t understand the physical meaning of a edge step normalized spectra. Is it the spectrum 1 x-ray photon would produce? Is it right that I loose the information of the absolute concentration after normalization so that I still can identify relative proportions of different compounds with in a sample but I can`t compare different spectra in an absolute way anymore? The extreme case would be a comparison of pure and a diluted spectra. jens ifeffit-request(a)millenia.cars.aps.anl.gov schrieb: > Send Ifeffit mailing list submissions to > ifeffit(a)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-request(a)millenia.cars.aps.anl.gov > > You can reach the person managing the list at > ifeffit-owner(a)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. Normalization of XANES spectra (Jens Kruse) > 2. Re: Normalization of XANES spectra (Frenkel, Anatoly) > 3. Re: Normalization of XANES spectra (Scott Calvin) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 29 Oct 2008 15:02:54 +0100 > From: Jens Kruse <jens.kruse(a)uni-rostock.de> > Subject: [Ifeffit] Normalization of XANES spectra > To: ifeffit(a)millenia.cars.aps.anl.gov > Message-ID: <49086D0E.2000603(a)uni-rostock.de> > Content-Type: text/plain; charset="ISO-8859-15"; format=flowed > > Hi everyone, > > I have a general question: > I know Normalizing is something we do so that we can compare samples > measured > under different experimental conditions (removes the effect of different > gains ...) but I have problems in understanding and applying > normalization when also quantitative conclusions are needed when > comparing different spectra. > > If I have two XANES spectra (a) and (b) measure under the same > conditions but with different concentration of the absorbing atom with > in different molecules.If both normalized spectra show a peak 1 , but > this peak is higher in intensity in spectrum (a) than in spectrum (b), > does this mean that compound which produced peak 1 is also absolute > higher in concentration in sample/spectrum (a) or do I loose this > information after normalization? > Or can I just say: in the normalized spectrum (a) peak 1 is higher than > peak 2 suggesting that the compound leading to peak 1 is more abundant > (just relative proportions).But I can't say: The intensity of peak 1 in > the also normalized spectrum 2 is lower than in spectrum one, Therefore, > the compound leading to peak 1 is less abundant in spectrum/sample 2. ???? > > > I hope somebody can help me to understand this issue. > > Thanks a lot, > > jens > > -- Jens Kruse Institute for Land Use Faculty for Agricultural and Environmental Sciences Rostock University Justus-von-Liebig-Weg 6 18059 Rostock GERMANY Phone: +49(0)381-498 3190

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Your internet exchange with "Chachi" about FeCo last year
by Alan English 29 Oct '08

29 Oct '08

Dear Sir: I just ran across your exchange of ideas on FeCo order etc. about this time last year. I did some experiments in the mid 60s (Trans. Met. Soc AIME 236 (1966) 14ff.) on FeCo2V and showed that the superlattice xray line [100} can be seen in brine-quenched thin strips if the XRD is done with CoKa radiation. The lines are very broad in as-quenched state and the peak narrows gradually with time of reheating to a few hundred degrees C. The interpretation was that we were seeing APB domains which were unexpected but seemed obvious in hindsight--two interpenetrating, multiply-connected domains sort of like "swiss cheese" (J. W. Cahn called it "sponge" at the time--he wrote an elegant mathematical analysis that appeared in Acta Met.). The "scale" of interconnection changes with time at temperature as the structure coarsens to reduce the energy associated with APB. I thought the picture was confusing since "perfect order with very fine domain size" could as well be described as partial, or incomplete order due to large number of wrong near neighbors. I don't know if there are other alloys or chemical combinations in which B2 order is present with very fine domain structure such as I described. I am not aware of any other work that confirmed or reinterpreted my results. Any comments? Alan English Summit NJ

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Fe L2 L3
by Guvenc Akgul (gakgul) 29 Oct '08

29 Oct '08

dear all, I have to calculate L3 and L2 absorption edges for pure Fe.how can I do this? thanks guven

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Normalization of XANES spectra
by Jens Kruse 29 Oct '08

29 Oct '08

Hi everyone, I have a general question: I know Normalizing is something we do so that we can compare samples measured under different experimental conditions (removes the effect of different gains ...) but I have problems in understanding and applying normalization when also quantitative conclusions are needed when comparing different spectra. If I have two XANES spectra (a) and (b) measure under the same conditions but with different concentration of the absorbing atom with in different molecules.If both normalized spectra show a peak 1 , but this peak is higher in intensity in spectrum (a) than in spectrum (b), does this mean that compound which produced peak 1 is also absolute higher in concentration in sample/spectrum (a) or do I loose this information after normalization? Or can I just say: in the normalized spectrum (a) peak 1 is higher than peak 2 suggesting that the compound leading to peak 1 is more abundant (just relative proportions).But I can't say: The intensity of peak 1 in the also normalized spectrum 2 is lower than in spectrum one, Therefore, the compound leading to peak 1 is less abundant in spectrum/sample 2. ???? I hope somebody can help me to understand this issue. Thanks a lot, jens -- Jens Kruse Institute for Land Use Faculty for Agricultural and Environmental Sciences Rostock University Justus-von-Liebig-Weg 6 18059 Rostock GERMANY Phone: +49(0)381-498 3190

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Re: [Ifeffit] Normalization of XANES spectra
by Frenkel, Anatoly 29 Oct '08

29 Oct '08

Jens: This example may help you understand your problem: if compound a) has a small fraction of metal Cu mixed with a large fraction of oxidized Cu, while a compound b) has it the other way around, then the main (1s - 4p) absorption peak in compound a) will be smaller than in b) after edge step normalization. Edge step normalization allows to view all features in XANES and EXAFS regions as if caused by an x-absorption process in a singe atom located in a concentration-average environment of all species in the sample that contain that element. Thus, the edge step normalization does have sensitivity to the composition of the sampe. Or, I misunderstood your question? Anatoly ----- Original Message ----- From: ifeffit-bounces(a)millenia.cars.aps.anl.gov <ifeffit-bounces(a)millenia.cars.aps.anl.gov> To: ifeffit(a)millenia.cars.aps.anl.gov <ifeffit(a)millenia.cars.aps.anl.gov> Sent: Wed Oct 29 10:02:54 2008 Subject: [Ifeffit] Normalization of XANES spectra Hi everyone, I have a general question: I know Normalizing is something we do so that we can compare samples measured under different experimental conditions (removes the effect of different gains ...) but I have problems in understanding and applying normalization when also quantitative conclusions are needed when comparing different spectra. If I have two XANES spectra (a) and (b) measure under the same conditions but with different concentration of the absorbing atom with in different molecules.If both normalized spectra show a peak 1 , but this peak is higher in intensity in spectrum (a) than in spectrum (b), does this mean that compound which produced peak 1 is also absolute higher in concentration in sample/spectrum (a) or do I loose this information after normalization? Or can I just say: in the normalized spectrum (a) peak 1 is higher than peak 2 suggesting that the compound leading to peak 1 is more abundant (just relative proportions).But I can't say: The intensity of peak 1 in the also normalized spectrum 2 is lower than in spectrum one, Therefore, the compound leading to peak 1 is less abundant in spectrum/sample 2. ???? I hope somebody can help me to understand this issue. Thanks a lot, jens -- Jens Kruse Institute for Land Use Faculty for Agricultural and Environmental Sciences Rostock University Justus-von-Liebig-Weg 6 18059 Rostock GERMANY Phone: +49(0)381-498 3190 _______________________________________________ Ifeffit mailing list Ifeffit(a)millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit

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Re: [Ifeffit] Fit XANES spectra using Athena
by Frenkel, Anatoly 28 Oct '08

28 Oct '08

PCA works only if there are series of spectra with change in the makeup of S species, not for a single spectrum. Anatoly ----- Original Message ----- From: ifeffit-bounces(a)millenia.cars.aps.anl.gov <ifeffit-bounces(a)millenia.cars.aps.anl.gov> To: ifeffit(a)millenia.cars.aps.anl.gov <ifeffit(a)millenia.cars.aps.anl.gov> Sent: Sun Oct 26 13:05:32 2008 Subject: Re: [Ifeffit] Fit XANES spectra using Athena Jenny, I'm relatively new to the community XAFS, and have not done any sulfur work thus far... but have you considered doing a principal component analysis on the XANES of your samples? This method should help you identify how many phases are present (assuming that all of your samples aren't exactly identical; however the maximum number of independent phases it will return is the number of samples you tested), and with your standards you might be able to eliminate some of the phases (from the standards) as well as identify some of the phases that are in your sample. (There is software that will do this in the IFFEFIT package under Sixpack --> 'pc analysis') Andrew Campos _______________________________________________ Ifeffit mailing list Ifeffit(a)millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit

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