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

Re: [Ifeffit] Ifeffit Digest, Vol 81, Issue 25
by Jasquelin Pena 30 Nov '09

30 Nov '09

Scott, .cif files for many minerals can be downloaded from the AMCSD: http://rruff.geo.arizona.edu/AMS/amcsd.php Jasquelin On Mon, 30 Nov 2009, 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: Request a .cif file for alpha & beta Nickel hydroxide > (Scott Wicker (Student)) > 2. Re: Request a .cif file for alpha & beta Nickel hydroxide > (Bruce Ravel) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sun, 29 Nov 2009 12:06:19 -0600 > From: "Scott Wicker (Student)" <scott_wicker_00(a)subr.edu> > To: "XAFS Analysis using Ifeffit" <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: Re: [Ifeffit] Request a .cif file for alpha & beta Nickel > hydroxide > Message-ID: > <301F55994159DB4682AA882A772707E1013EF192(a)primary14.subr.edu> > Content-Type: text/plain; charset="iso-8859-1" > > I would like to request a .cif file for the alpha & beta Nickel hydroxide. If someone also have .cif files for Cobalt hydroxide this will be greatly appreciated. Is there a single crystal data base for .cif files? > > thanks, > > Scott A. Wicker Sr. > Ph.d Graduate Student > Environmental Toxicology > Southern University A & M > Baton Rouge, LA 70813 > School: scott_wicker_00(a)cxs.subr.edu > Home: swicker(a)cox.net > > > > -----Original Message----- > From: ifeffit-bounces(a)millenia.cars.aps.anl.gov on behalf of Frenkel, Anatoly > Sent: Fri 11/27/2009 1:12 PM > To: jswashin(a)ncsu.edu; XAFS Analysis using Ifeffit > Subject: RE: [Ifeffit] Bond length determination EXAFS vs XRD > > XRD measures interplanar spacing, and XAFS - interatomic distances, and they are not the same if disorder is present. Look for articles by Boyce and Mikkelsen, Jr., in Phys Rev B in 1980's who were the first discussing these concepts in GaAs-InAs semiconductors and also KBr-RbBr ionic salts. > They showed that the average structure ascertained by diffraction differs from the local structure measured by EXAFS. > Modern day high energy XRD/PDF measures interatomic distances more accurately than Bragg peak analysis can do but how accurately it agrees with EXAFS is still subject of debates. > Anatoly > > > _____ > > From: ifeffit-bounces(a)millenia.cars.aps.anl.gov on behalf of Joseph Washington > Sent: Fri 11/27/2009 2:08 PM > To: XAFS Analysis using Ifeffit > Subject: [Ifeffit] Bond length determination EXAFS vs XRD > > > > Happy Thanksgiving All! > > Can someone, send me some references which explains some of the reasons > why the bond lengths fitted in EXAFS would be different from that fitted > in XRD (assuming that we implemented the crystal model predicted by XRD > correctly in Artemis)? > > I would really appreciate this! > > Sincerely > -- > Joseph Washington > Research Assistant > Department of Physics > North Carolina State University > 431 Riddick Hall > Raleigh, NC 27695-8202 > email: jswashin(a)ncsu.edu > _______________________________________________ > Ifeffit mailing list > Ifeffit(a)millenia.cars.aps.anl.gov > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > > > >

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Request a .cif file for alpha & beta Nickel hydroxide
by Eugenio Otal 30 Nov '09

30 Nov '09

Try with this database: http://www.icsd.iqfr.csic.es/ Regards, euG

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Bond length determination EXAFS vs XRD
by Joseph Washington 30 Nov '09

30 Nov '09

Happy Thanksgiving All! Can someone, send me some references which explains some of the reasons why the bond lengths fitted in EXAFS would be different from that fitted in XRD (assuming that we implemented the crystal model predicted by XRD correctly in Artemis)? I would really appreciate this! Sincerely -- Joseph Washington Research Assistant Department of Physics North Carolina State University 431 Riddick Hall Raleigh, NC 27695-8202 email: jswashin(a)ncsu.edu

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Re: [Ifeffit] Path degeneracy modification in feffNNN.dat
by Frenkel, Anatoly 20 Nov '09

20 Nov '09

It takes it from N. 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: Fri Nov 20 18:57:29 2009 Subject: Re: [Ifeffit] Path degeneracy modification in feffNNN.dat Hi ｔｈｅｒｅ, I have a general question about Artemis. I am going to split a degenerated path with degeneracy N=8 into twoｓ. I noticed that by cloning the path, the "N" in path math expression parameters was halved as "4". However, the degeneracy number in feffNNN.dat remains as "8". For fitting, where will Artemis exactly get this information? Or maybe I　ｓｈｏｕｌｄ　ｍｏｄｉｆｙ　ｆｅｆｆＮＮＮ．ｄａｔ　ｍａｎｕａｌｌｙ？　　Ｔｈａｎｋｓ　ｆｏｒ　ｙｏｕｒ　ｒｅｓｐｏｎｓｅ！＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝Ｄｒ．　Ｙｉｎｇ　ＺｏｕＲｅｓｅａｒｃｈ　Ａｓｓｏｃｉａｔｅ，ＵＷＭ／Ｐｈｙｓｉｃｓ，１９００　Ｅ．　Ｋｅｎｗｏｏｄ　Ｂｌｖｄ，Ｍｉｌｗａｕｋｅｅ，　ＷＩ５３２１７＝＝＝＝＝＝＝＝＝＝＝＝＝＝ _______________________________________________ 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] Path degeneracy modification in feffNNN.dat
by Ying Zou 20 Nov '09

20 Nov '09

Hi ｔｈｅｒｅ, I have a general question about Artemis. I am going to split a degenerated path with degeneracy N=8 into twoｓ. I noticed that by cloning the path, the "N" in path math expression parameters was halved as "4". However, the degeneracy number in feffNNN.dat remains as "8". For fitting, where will Artemis exactly get this information? Or maybe I　ｓｈｏｕｌｄ　ｍｏｄｉｆｙ　ｆｅｆｆＮＮＮ．ｄａｔ　ｍａｎｕａｌｌｙ？　　Ｔｈａｎｋｓ　ｆｏｒ　ｙｏｕｒ　ｒｅｓｐｏｎｓｅ！＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝Ｄｒ．　Ｙｉｎｇ　ＺｏｕＲｅｓｅａｒｃｈ　Ａｓｓｏｃｉａｔｅ，ＵＷＭ／Ｐｈｙｓｉｃｓ，１９００　Ｅ．　Ｋｅｎｗｏｏｄ　Ｂｌｖｄ，Ｍｉｌｗａｕｋｅｅ，　ＷＩ５３２１７＝＝＝＝＝＝＝＝＝＝＝＝＝＝

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E0 problems
by Chris Patridge 17 Nov '09

17 Nov '09

Hello, I am having some trouble with a first shell fitting. I have good reason to believe that the compound crystal structure should be quite similar to the starting input structure from other reliable analysis. The closest neighbor paths V-O is 1.61 A away so I set R to 0.8 as a start. I summed what I think are pertinent paths together and tried to fit these paths to a first shell. The bmp file attached contains the fit, summed paths, and the data all in R-space. The fit comes away with a small amplitude, huge E0 of close to -21 eV and negative delr & ss. I have included the artemis project. Is the k-space any indication that the data is too noisy? Any suggestions and or questions would be greatly appreciated. Thank you all, Chris Patridge UB Graduate Student Department of Chemistry Cell: 315-529-0501

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SO2 parameter for Cu2O
by abhijeet gaur 12 Nov '09

12 Nov '09

Hi all, I am fitting Cu2O EXAFS data taken at SSRL using the Artemis. But there is a problem with fitting results that SO2 parameter is coming very low around 0.50. I had also taken Cu2O data from different data bases to check whether theere some problem with my data, but after fitting them, the same problem of low SO2 is coming. In some research papers given SO2 parameter for Cu2O equal to 0.82. But I am unable to get that why all the Cu2O data giving low value of SO2. Is there any other fitting procedure to fit the compounds like Cu2O ?????? With thanks Abhijeet Gaur

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Re: [Ifeffit] Question about ATHENA software
by Bruce Ravel 12 Nov '09

12 Nov '09

Claudia, The implementation of the XANES self-absorption corrections follows the thing that Daniel Haskel wrote up here: http://www.aps.anl.gov/xfd/people/haskel/fluo.html The algorithm used is explained on pages 5-9 of the postscript file on that web page. The angles are defined relative to the surface, not the surface normal. HTH, B PS: You should consider joining the Ifeffit mailing list: (http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit) It is a very useful resource for siftware and for XAS in general. On Saturday 07 November 2009 02:22:45 pm you wrote: > Dear Bruce Ravel, > > I am a PhD student currently working with the ATHENA software. I came > across a question which I could not answer even after searching the > internet for hours. I hope you might have the time to briefly answer my > question. > > The self-absorption dialog requires the incoming (angle in) and the > outgoing angle (angle out) as an input. My basic question is: Are these > angles referenced to the sample surface or to the normal of the surface? > I would not worry about that if I had measured in 45deg geometry (as in > your tutorial example). However, I did not and therefore it makes a > large difference. > > I strongly apologize bothering you with such a basic question. > Many thanks in advance. > Best regards, > Claudia Fleischmann -- 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 My homepage: http://xafs.org/BruceRavel EXAFS software: http://cars9.uchicago.edu/~ravel/software/exafs/

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SO2 parameter problem
by abhijeet gaur 12 Nov '09

12 Nov '09

Hi all, I am fitting CuO2 EXAFS data taken at SSRL using the Artemis. But there is a problem with fitting results that SO2 parameter is coming very low around 0.50. I had also taken CuO2 data from different data bases to check whether theere some problem with my data, but after fitting them, the same problem of low SO2 is coming. In some research papers given SO2 parameter for CuO2 equal to 0.82. But I am unable to get that why all the CuO2 data giving low value of SO2. Is there any other fitting procedure to fit the compounds like CuO2 ?????? With thanks Abhijeet Gaur

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Why I can't install ifeffit?
by 康明亮 10 Nov '09

10 Nov '09

Dear, I don't konw why I can't intall ifeffit. As I run the Anthena programm, it prompted me the following message: Cannot execute grwnd.exe to open the graphics window. I don;t know how to resolve this problem. wish to obtain guidance. Thank you. Best regards Mingliang

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