- Ifeffit - millenia.cars.aps.anl.gov

Re: [Ifeffit] Ifeffit Digest, Vol 113, Issue 18
by Michael Weir 30 Jul '12

30 Jul '12

Hello Branko, I've worked a little bit with small Pt nanoparticles and I think I may see a problem. In the project file you sent us, you choose an Rbkg of 1.6 for your nanoparticles but 1.0 for the foil. The Pt-O bonds at ~ 2 A end up at about 1.5/1.55 A in the Fourier Transform, so your choice of Rbkg is suppressing the real signal in that region. I'd look again with a lower Rbkg if you haven't already (1.2 is a good starting point). I didn't see your Pt-O standards in the project. Also keep in mind that Artemis will plot individual paths from the FEFF calculation, which is really useful for determining if a specific path has a strong contribution to your fit or if a pair of paths will be difficult to distinguish. I hope that helps! Michael Weir On Mon, Jul 30, 2012 at 9:01 AM, <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. Re: Ifeffit Digest, Vol 113, Issue 17 (Branko Zugic) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 30 Jul 2012 12:00:37 -0400 > From: Branko Zugic <brankozugic(a)gmail.com> > To: ifeffit(a)millenia.cars.aps.anl.gov > Subject: Re: [Ifeffit] Ifeffit Digest, Vol 113, Issue 17 > Message-ID: > <CAOJ5_YxOhbiN8zJfi_xG8+NSVuhnfTydyR== > xc61Uov-CwdhMw(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hi Anatoly, > > I've only tried approximating using the short bond at 2 A up until now. > Below are the spectra that I'm trying to interpret. These are merged QEXAFS > data taken at increasing temperature under WGS conditions. Perhaps I > haven't processed them well enough? There certainly seem to be changes > taking place during the course of reaction, which I'm trying to interpret. > > Given that the material starts out very well dispersed (I've observed many > sub-nm Pt clusters via ac-STEM) and grow to 1-2 nm particles during > reaction, I would expect to observe corresponding structural changes during > reaction. I also observe significant changes in the EXAFS spectra when > alternating between WGS gas and He - hence my thought to including some > kind of Pt-C and Pt-O paths, similar to those used in the Ir4(CO)12 work. > > Thanks for any help! > > > Branko > > > > On Sat, Jul 28, 2012 at 1:00 PM, > <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. Re: Modeling Pt/C Catalyst Under WGS Conditions > > (Anatoly I Frenkel) > > > > > > ---------------------------------------------------------------------- > > > > Message: 1 > > Date: Sat, 28 Jul 2012 01:02:23 +0000 > > From: Anatoly I Frenkel <afrenke2(a)yu.edu> > > To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> > > Subject: Re: [Ifeffit] Modeling Pt/C Catalyst Under WGS Conditions > > Message-ID: <98fc47e6-bd47-4c56-8fb2-3385fa7dbbbe@blur> > > Content-Type: text/plain; charset="utf-8" > > > > Maybe your system is more complex? Have you included a long Pt-O bond at > > around 2.5 A or just a short one at around 2A? Hard to help without > seeing > > what the problem is. > > > > Anatoly > > > > > > > > Sent from my mobile phone, please forgive typos > > > > > > -----Original message----- > > From: Branko Zugic <Branko.Zugic(a)tufts.edu> > > To: "ifeffit(a)millenia.cars.aps.anl.gov" < > ifeffit(a)millenia.cars.aps.anl.gov > > > > > Sent: Fri, Jul 27, 2012 15:28:37 GMT+00:00 > > Subject: [Ifeffit] Modeling Pt/C Catalyst Under WGS Conditions > > > > Hello, > > > > I am trying to interpret some in-situ Quick-EXAFS and EXAFS data that I > > took under water-gas shift conditions (CO + H2O diluted in He) on some > Pt/C > > catalysts. I'm finding that the Pt-Pt and Pt-O fits using foil data, Pt-O > > standards, and quick 1st shell approximations for Pt-O aren't that great. > > After looking through the literature I came across some papers (i.e. > > http://pubs.acs.org/doi/abs/10.1021/jp983283e) that use the Ir-O and > Ir-C > > interactions from Ir4(CO)12 to approximate Pt-O and Pt-C interactions. I > > then found some crystallographic tables for Ir4(CO)12 (below), but it's > > unclear to me whether I can use this to create an atoms inp file (and > > whether the data is for the structure I'm looking for or the referenced > > Ir(CO)3). So far I've had no luck. > > > > Is this a reasonable approach to this problem? Is the information I have > > enough to do this? Any suggestions as to where I may be able to find the > > crystallographic data I am looking for? > > > > > > Branko Zugic > > > > > > -- > > PhD Candidate > > Tufts University, Chemical and Biological Engineering > > 4 Colby Street, Room 226 > > Medford, MA 02155 > > Ph: (O) 617 627 2267 (H) 508 414 8555 > > Email: Branko.Zugic(a)tufts.edu<mailto:Branko.Zugic@tufts.edu>, > > brankozugic(a)gmail.com<mailto:brankozugic@gmail.com><mailto: > > brankozugic(a)gmail.com> > >

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Re: [Ifeffit] Ifeffit Digest, Vol 113, Issue 17
by Branko Zugic 30 Jul '12

30 Jul '12

Hi Anatoly, I've only tried approximating using the short bond at 2 A up until now. Below are the spectra that I'm trying to interpret. These are merged QEXAFS data taken at increasing temperature under WGS conditions. Perhaps I haven't processed them well enough? There certainly seem to be changes taking place during the course of reaction, which I'm trying to interpret. Given that the material starts out very well dispersed (I've observed many sub-nm Pt clusters via ac-STEM) and grow to 1-2 nm particles during reaction, I would expect to observe corresponding structural changes during reaction. I also observe significant changes in the EXAFS spectra when alternating between WGS gas and He - hence my thought to including some kind of Pt-C and Pt-O paths, similar to those used in the Ir4(CO)12 work. Thanks for any help! Branko On Sat, Jul 28, 2012 at 1:00 PM, <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. Re: Modeling Pt/C Catalyst Under WGS Conditions > (Anatoly I Frenkel) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 28 Jul 2012 01:02:23 +0000 > From: Anatoly I Frenkel <afrenke2(a)yu.edu> > To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: Re: [Ifeffit] Modeling Pt/C Catalyst Under WGS Conditions > Message-ID: <98fc47e6-bd47-4c56-8fb2-3385fa7dbbbe@blur> > Content-Type: text/plain; charset="utf-8" > > Maybe your system is more complex? Have you included a long Pt-O bond at > around 2.5 A or just a short one at around 2A? Hard to help without seeing > what the problem is. > > Anatoly > > > > Sent from my mobile phone, please forgive typos > > > -----Original message----- > From: Branko Zugic <Branko.Zugic(a)tufts.edu> > To: "ifeffit(a)millenia.cars.aps.anl.gov" <ifeffit(a)millenia.cars.aps.anl.gov > > > Sent: Fri, Jul 27, 2012 15:28:37 GMT+00:00 > Subject: [Ifeffit] Modeling Pt/C Catalyst Under WGS Conditions > > Hello, > > I am trying to interpret some in-situ Quick-EXAFS and EXAFS data that I > took under water-gas shift conditions (CO + H2O diluted in He) on some Pt/C > catalysts. I'm finding that the Pt-Pt and Pt-O fits using foil data, Pt-O > standards, and quick 1st shell approximations for Pt-O aren't that great. > After looking through the literature I came across some papers (i.e. > http://pubs.acs.org/doi/abs/10.1021/jp983283e) that use the Ir-O and Ir-C > interactions from Ir4(CO)12 to approximate Pt-O and Pt-C interactions. I > then found some crystallographic tables for Ir4(CO)12 (below), but it's > unclear to me whether I can use this to create an atoms inp file (and > whether the data is for the structure I'm looking for or the referenced > Ir(CO)3). So far I've had no luck. > > Is this a reasonable approach to this problem? Is the information I have > enough to do this? Any suggestions as to where I may be able to find the > crystallographic data I am looking for? > > > Branko Zugic > > > -- > PhD Candidate > Tufts University, Chemical and Biological Engineering > 4 Colby Street, Room 226 > Medford, MA 02155 > Ph: (O) 617 627 2267 (H) 508 414 8555 > Email: Branko.Zugic(a)tufts.edu<mailto:Branko.Zugic@tufts.edu>, > brankozugic(a)gmail.com<mailto:brankozugic@gmail.com><mailto: > brankozugic(a)gmail.com> >

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Re: [Ifeffit] Modeling Pt/C Catalyst Under WGS Conditions
by Anatoly I Frenkel 28 Jul '12

28 Jul '12

Maybe your system is more complex? Have you included a long Pt-O bond at around 2.5 A or just a short one at around 2A? Hard to help without seeing what the problem is. Anatoly Sent from my mobile phone, please forgive typos -----Original message----- From: Branko Zugic <Branko.Zugic(a)tufts.edu> To: "ifeffit(a)millenia.cars.aps.anl.gov" <ifeffit(a)millenia.cars.aps.anl.gov> Sent: Fri, Jul 27, 2012 15:28:37 GMT+00:00 Subject: [Ifeffit] Modeling Pt/C Catalyst Under WGS Conditions Hello, I am trying to interpret some in-situ Quick-EXAFS and EXAFS data that I took under water-gas shift conditions (CO + H2O diluted in He) on some Pt/C catalysts. I'm finding that the Pt-Pt and Pt-O fits using foil data, Pt-O standards, and quick 1st shell approximations for Pt-O aren't that great. After looking through the literature I came across some papers (i.e. http://pubs.acs.org/doi/abs/10.1021/jp983283e) that use the Ir-O and Ir-C interactions from Ir4(CO)12 to approximate Pt-O and Pt-C interactions. I then found some crystallographic tables for Ir4(CO)12 (below), but it's unclear to me whether I can use this to create an atoms inp file (and whether the data is for the structure I'm looking for or the referenced Ir(CO)3). So far I've had no luck. Is this a reasonable approach to this problem? Is the information I have enough to do this? Any suggestions as to where I may be able to find the crystallographic data I am looking for? Branko Zugic -- PhD Candidate Tufts University, Chemical and Biological Engineering 4 Colby Street, Room 226 Medford, MA 02155 Ph: (O) 617 627 2267 (H) 508 414 8555 Email: Branko.Zugic(a)tufts.edu<mailto:Branko.Zugic@tufts.edu>, brankozugic(a)gmail.com<mailto:brankozugic@gmail.com><mailto:brankozugic@gmail.com>

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Modeling Pt/C Catalyst Under WGS Conditions
by Branko Zugic 27 Jul '12

27 Jul '12

Hello, I am trying to interpret some in-situ Quick-EXAFS and EXAFS data that I took under water-gas shift conditions (CO + H2O diluted in He) on some Pt/C catalysts. I'm finding that the Pt-Pt and Pt-O fits using foil data, Pt-O standards, and quick 1st shell approximations for Pt-O aren't that great. After looking through the literature I came across some papers (i.e. http://pubs.acs.org/doi/abs/10.1021/jp983283e) that use the Ir-O and Ir-C interactions from Ir4(CO)12 to approximate Pt-O and Pt-C interactions. I then found some crystallographic tables for Ir4(CO)12 (below), but it's unclear to me whether I can use this to create an atoms inp file (and whether the data is for the structure I'm looking for or the referenced Ir(CO)3). So far I've had no luck. Is this a reasonable approach to this problem? Is the information I have enough to do this? Any suggestions as to where I may be able to find the crystallographic data I am looking for? Branko Zugic -- PhD Candidate Tufts University, Chemical and Biological Engineering 4 Colby Street, Room 226 Medford, MA 02155 Ph: (O) 617 627 2267 (H) 508 414 8555 Email: Branko.Zugic(a)tufts.edu, brankozugic(a)gmail.com <brankozugic(a)gmail.com>

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Demeter 0.9.10
by Bruce Ravel 17 Jul '12

17 Jul '12

Hi everyone, I just uploaded a new version of the Demeter installer for Windows -- which includes the programs Athena, Artemis, and Hephaestus -- to its download site at https://github.com/bruceravel/demeter/downloads The current version number is 0.9.10. I also tagged this version in the github repository for anyone interested in a tagged version of the source code. Installation instructions for all platforms are at http://bruceravel.github.com/demeter/pods/installation.pod.html While there are no major new features in this release, the list of bug fixes and improvements is rather lengthy. Here are the details: https://github.com/bruceravel/demeter/blob/master/Changes.org Here are hints for making helpful bugs reports: http://bruceravel.github.com/demeter/pods/bugs.pod.html Documentation about Demeter in various kinds of media can found at http://bruceravel.github.com/demeter/ As a closing note, I want to mention that I am about 2/3 done with the long-awaited users' guide for Artemis. There is a link to the current (but incomplete) draft at the Documentation site. I will update that as I work it. Once it is complete, I will work on a PDF version. Once that is complete (and assuming I still have energy for such things!), I will work on updating the Athena Users' Guide for the new Demeter-based version. Whew! As always, thanks to everyone who uses my software. Your enthusiasm is a huge inspiration for me. Bruce PS: If, in the last few months, you have reported a bug or requested a feature that is not in this release, please remind me! -- Bruce Ravel ------------------------------------ bravel(a)bnl.gov National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973 Homepage: http://xafs.org/BruceRavel Software: https://github.com/bruceravel

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"Re: Contents of Ifeffit digest..."
by johnny huertas 15 Jul '12

15 Jul '12

Anatoly: Thanks so much. Jhonny Huertas Flores Rio de Janeiro-Brasil > From: ifeffit-request(a)millenia.cars.aps.anl.gov > Subject: Ifeffit Digest, Vol 113, Issue 13 > To: ifeffit(a)millenia.cars.aps.anl.gov > Date: Sat, 14 Jul 2012 16:19:14 -0500 > > 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. Re: Ifeffit Digest, Vol 113, Issue 11 (Anatoly I Frenkel) > 2. "RE: Contents of Ifeffit digest..." (johnny huertas) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 14 Jul 2012 19:13:01 +0000 > From: Anatoly I Frenkel <afrenke2(a)yu.edu> > To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: Re: [Ifeffit] Ifeffit Digest, Vol 113, Issue 11 > Message-ID: > <545F89325F51764C902D37B42C9F4D53135B1B44(a)YUWEXCPM12.yuad.uds.yu.edu> > Content-Type: text/plain; charset="iso-8859-1" > > Hi Jhonny, > > This article on AgBr(x)Cl(1-x) explains how to do this type of analysis, and if there are still questions, look for other articles (in Phys. Rev. B and Phys. Rev. Lett.) on mixed ionic salts, by the same authors: > > https://pubweb.bnl.gov/~frenkel/BUCKLING-PHB/buckledPHB.pdf > > It is a model independent way to find local composition of Br and Cl around Ag. You are better off doing that (limit it to the 1st shell analysis) rather than using particular configurations you are proposing, and then see if you get the same composition (x) for Ag-Br as you obtain for composition y corresponding to the Br-Br coordination number found from Br K-edge. That will mean that your alloy is random. Otherwise, there may be either short range order or segregation that you will be able to identify by comparing x and y in each individual case. Rely on XRD results also, to tell whether you really have a solid solution or not. > > If you only measured Ag edge, you still can make some conclusions but you should rely on the bulk composition to compare the "x" and "y". > > Anatoly > > > ________________________________ > From: ifeffit-bounces(a)millenia.cars.aps.anl.gov [ifeffit-bounces(a)millenia.cars.aps.anl.gov] on behalf of johnny huertas [johnnyhf(a)hotmail.com] > Sent: Saturday, July 14, 2012 1:51 PM > To: Lista fe IFEFFIT > Subject: Re: [Ifeffit] Ifeffit Digest, Vol 113, Issue 11 > > Hi Matt: > Thanks for your response. First of all I am beginner in this issue. Because of my little experience I don't know exactly how to specify my problem but I think you write an interesting phrase in your response: "are you asking if you can distinguish random substitution from ordered substitution? I'm not sure why the Ag-Br and Ag-Cl parameters would be the same". > I don't know how to create a robust fitting model to distinguish random substitution from ordered substitution of the example found in Bruce site about AgBr(1-x)Clx. What are the parameters that I must consider to fit the spectra and to verify if exist random or ordered substitution? I am attaching a document very explicit about this. Thanks again. > > > > > Jhonny Huertas Flores > Rio de Janeiro-Brasil > > > > > From: ifeffit-request(a)millenia.cars.aps.anl.gov > > Subject: Ifeffit Digest, Vol 113, Issue 11 > > To: ifeffit(a)millenia.cars.aps.anl.gov > > Date: Sat, 14 Jul 2012 12:00:01 -0500 > > > > 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. problems (johnny huertas) > > 2. Re: problems (Matt Newville) > > > > > > ---------------------------------------------------------------------- > > > > Message: 1 > > Date: Fri, 13 Jul 2012 22:21:50 +0000 > > From: johnny huertas <johnnyhf(a)hotmail.com> > > To: <ifeffit(a)millenia.cars.aps.anl.gov> > > Subject: [Ifeffit] problems > > Message-ID: <BAY167-W124DD69B56D1526E67FEC05D5D70(a)phx.gbl> > > Content-Type: text/plain; charset="iso-8859-1" > > > > > > Members of list: > > I have some problems to resolve a question. I have been working a lot in fit the AgBr(1-x)Clx example of FEFFIT site. My fits were good in my opinion, but I don't know how to identify the Br and Cl atomic distribution around Ag (random or specific?). I didn't find any example about this in the site. Conversely I have made some attempts to identify such distribution. I have made two fits preparing for each one feff file, a feff file puting Br and Cl atoms in face and other in medirian position around Ag knowing the CN=6 of this central atom and fiting only the first shell. Unfortunatelly I don't have found satisfactory results because the paremeter are equal in both cases. I would like you help showing a similar example. Thanks. > > Jhonny Huertas Flores > > Rio de Janeiro-Brasil > > > > > >

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"RE: Contents of Ifeffit digest..."
by johnny huertas 15 Jul '12

15 Jul '12

Hi Matt: Thanks for your response. First of all I am beginner in this issue. Because of my little experience I don't know exactly how to specify my problem but I think you write an interesting phrase in your response: "are you asking if you can distinguish random substitution from ordered substitution? I'm not sure why the Ag-Br and Ag-Cl parameters would be the same".I don't know how to create a robust fitting model to distinguish random substitution from ordered substitution of the example found in Bruce site about AgBr(1-x)Clx. What are the parameters that I must consider to fit the spectra and to verify if exist random or ordered substitution? I am attaching a document very explicit about this. Thanks again. Jhonny Huertas Flores Rio de Janeiro-Brasil > From: ifeffit-request(a)millenia.cars.aps.anl.gov > Subject: Ifeffit Digest, Vol 113, Issue 12 > To: ifeffit(a)millenia.cars.aps.anl.gov > Date: Sat, 14 Jul 2012 13:42:01 -0500 > > 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. Re: Ifeffit Digest, Vol 113, Issue 11 (johnny huertas) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 14 Jul 2012 17:51:20 +0000 > From: johnny huertas <johnnyhf(a)hotmail.com> > To: Lista fe IFEFFIT <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: Re: [Ifeffit] Ifeffit Digest, Vol 113, Issue 11 > Message-ID: <BAY167-W39E4C96CF961ED74CD8924D5D60(a)phx.gbl> > Content-Type: text/plain; charset="iso-8859-1" > > > Hi Matt:Thanks for your response. First of all I am beginner in this issue. Because of my little experience I don't know exactly how to specify my problem but I think you write an interesting phrase in your response: "are you asking if you can distinguish random substitution from ordered substitution? I'm not sure why the Ag-Br and Ag-Cl parameters would be the same".I don't know how to create a robust fitting model to distinguish random substitution from ordered substitution of the example found in Bruce site about AgBr(1-x)Clx. What are the parameters that I must consider to fit the spectra and to verify if exist random or ordered substitution? I am attaching a document very explicit about this. Thanks again. > > Jhonny Huertas Flores > Rio de Janeiro-Brasil > > > > From: ifeffit-request(a)millenia.cars.aps.anl.gov > > Subject: Ifeffit Digest, Vol 113, Issue 11 > > To: ifeffit(a)millenia.cars.aps.anl.gov > > Date: Sat, 14 Jul 2012 12:00:01 -0500 > > > > 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. problems (johnny huertas) > > 2. Re: problems (Matt Newville) > > > > > > ---------------------------------------------------------------------- > > > > Message: 1 > > Date: Fri, 13 Jul 2012 22:21:50 +0000 > > From: johnny huertas <johnnyhf(a)hotmail.com> > > To: <ifeffit(a)millenia.cars.aps.anl.gov> > > Subject: [Ifeffit] problems > > Message-ID: <BAY167-W124DD69B56D1526E67FEC05D5D70(a)phx.gbl> > > Content-Type: text/plain; charset="iso-8859-1" > > > > > > Members of list: > > I have some problems to resolve a question. I have been working a lot in fit the AgBr(1-x)Clx example of FEFFIT site. My fits were good in my opinion, but I don't know how to identify the Br and Cl atomic distribution around Ag (random or specific?). I didn't find any example about this in the site. Conversely I have made some attempts to identify such distribution. I have made two fits preparing for each one feff file, a feff file puting Br and Cl atoms in face and other in medirian position around Ag knowing the CN=6 of this central atom and fiting only the first shell. Unfortunatelly I don't have found satisfactory results because the paremeter are equal in both cases. I would like you help showing a similar example. Thanks. > > Jhonny Huertas Flores > > Rio de Janeiro-Brasil > > > > > >

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Re: [Ifeffit] Ifeffit Digest, Vol 113, Issue 11
by johnny huertas 14 Jul '12

14 Jul '12

Hi Matt:Thanks for your response. First of all I am beginner in this issue. Because of my little experience I don't know exactly how to specify my problem but I think you write an interesting phrase in your response: "are you asking if you can distinguish random substitution from ordered substitution? I'm not sure why the Ag-Br and Ag-Cl parameters would be the same".I don't know how to create a robust fitting model to distinguish random substitution from ordered substitution of the example found in Bruce site about AgBr(1-x)Clx. What are the parameters that I must consider to fit the spectra and to verify if exist random or ordered substitution? I am attaching a document very explicit about this. Thanks again. Jhonny Huertas Flores Rio de Janeiro-Brasil > From: ifeffit-request(a)millenia.cars.aps.anl.gov > Subject: Ifeffit Digest, Vol 113, Issue 11 > To: ifeffit(a)millenia.cars.aps.anl.gov > Date: Sat, 14 Jul 2012 12:00:01 -0500 > > 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. problems (johnny huertas) > 2. Re: problems (Matt Newville) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 13 Jul 2012 22:21:50 +0000 > From: johnny huertas <johnnyhf(a)hotmail.com> > To: <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: [Ifeffit] problems > Message-ID: <BAY167-W124DD69B56D1526E67FEC05D5D70(a)phx.gbl> > Content-Type: text/plain; charset="iso-8859-1" > > > Members of list: > I have some problems to resolve a question. I have been working a lot in fit the AgBr(1-x)Clx example of FEFFIT site. My fits were good in my opinion, but I don't know how to identify the Br and Cl atomic distribution around Ag (random or specific?). I didn't find any example about this in the site. Conversely I have made some attempts to identify such distribution. I have made two fits preparing for each one feff file, a feff file puting Br and Cl atoms in face and other in medirian position around Ag knowing the CN=6 of this central atom and fiting only the first shell. Unfortunatelly I don't have found satisfactory results because the paremeter are equal in both cases. I would like you help showing a similar example. Thanks. > Jhonny Huertas Flores > Rio de Janeiro-Brasil > > >

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problems
by johnny huertas 14 Jul '12

14 Jul '12

Members of list: I have some problems to resolve a question. I have been working a lot in fit the AgBr(1-x)Clx example of FEFFIT site. My fits were good in my opinion, but I don't know how to identify the Br and Cl atomic distribution around Ag (random or specific?). I didn't find any example about this in the site. Conversely I have made some attempts to identify such distribution. I have made two fits preparing for each one feff file, a feff file puting Br and Cl atoms in face and other in medirian position around Ag knowing the CN=6 of this central atom and fiting only the first shell. Unfortunatelly I don't have found satisfactory results because the paremeter are equal in both cases. I would like you help showing a similar example. Thanks. Jhonny Huertas Flores Rio de Janeiro-Brasil

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Re: [Ifeffit] Referencing Demeter
by Bruce Ravel 13 Jul '12

13 Jul '12

Daniel, Please use the Ifeffit mailing list questions and comments on the software. http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > My name is Daniel Whittaker, I am PhD student at the University of > Manchester, UK. I have used your Demeter software (Athena and Artemis - i > used the first shell fit method as reading in crystal data was very > problematic) to model some EXAFS data. I am now preparing the manuscript > for publication and was wondering how you would like referencing (other > than Bruce Ravels Demeter software package) and if there is anything in > particular you would like in the experimental section about how the > software works? I have looked on your page and couldn't seem to find > anything that explicit requests referencing in a particular format. Ravel, B. & Newville, M. athena and artemis: data analysis for X-ray absorption spectroscopy using ifeffit, Journal of Synchrotron Radiation 12, 537–541 (2005) http://dx.doi.org/10.1107/S0909049505012719 > Thanks for your help with this and for producing the package in the first > place, as someone who knew literally nothing when i started i have managed > to model quite a few spectra to a satisfactory level. > > Regards, > > Daniel Whittaker, MChem > Nuclear FiRST DTC PhD Student > The University of Manchester > Oxford Road > Manchester > M13 9PL -- Bruce Ravel ------------------------------------ bravel(a)bnl.gov National Institute of Standards and Technology Synchrotron Methods Group at NSLS --- Beamlines U7A, X24A, X23A2 Building 535A Upton NY, 11973 Homepage: http://xafs.org/BruceRavel Software: https://github.com/bruceravel

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