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

Fitting results
by Abhijeet Gaur 21 Jan '10

21 Jan '10

Hello Sir, I had done fitting of a Cu2O data taken at SSRL EXAFS beamline in transmission mode, Stanford, by my research guide Dr. B. D. Shrivastava. I had used here the fiting procedure as discussed before in this mailing list. The fitted curves are coming nice, but the values of some fitting parameters are not reliable as shown * bold* below. *amp = 0.4898160 +/- 0.0469990 (1.0000) * enot = 7.6843630 +/- 0.4828620 (0.0000) alpha = 0.0022670 +/- 0.0030950 (0.0000) * ss011 = 0.0003280 +/- 0.0013130 (0.0030) * sscu11 = 0.0174780 +/- 0.0016220 (0.0030) *sscu11o11 = 0.0470530 +/- 0.0655560 (0.0030) * ss012 = 0.0070100 +/- 0.0044660 (0.0030) sscu12 = 0.0186980 +/- 0.0093570 (0.0030) * ss013cu11 = 0.0088980 +/- 0.0190580 (0.0030) * sscu13 = 0.0196150 +/- 0.0062940 (0.0030) sscu13012 = 0.0084870 +/- 0.0067030 (0.0030) * sscu11cu11 = 0.0071110 +/- 0.0132390 (0.0030) sscu12cu11 = 0.0111440 +/- 0.0139470 (0.0030)* Def parameters (using "FEFF0: Path 1: [O1_1]"): delr = 0.0041920 So, if someone can please tell me that where I had done wrong or what should I do to make things right I will be very thankful. The Artemis project file is attached herewith. With regards Abhijeet Gaur Research Scholar School of Studies in Physics Vikram University, Ujjain (INDIA)

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Problem opening up project files
by Lisa Van Loon 20 Jan '10

20 Jan '10

Hi, I am using Athena in Windows and I have been having trouble with some project files. I would like to determine the cause: after closing the original file I am unable to reopen the project file again properly. I have attached a file to demonstrate the problem (test1.prj) Saving different versions does not help. When I open the file, no spectrum is displayed. (If I click on a file during the importing then that spectrum will remain displayed). At the bottom the "removing background..." never says "done". It seems like everything is working except the graphing window. I haven't been able to determine what is different about this data from other data that opens without any problem. I would appreciate any help with this. Thanks, Lisa Lisa Van Loon, Ph.D. Industrial Research Scientist lisa.vanloon(a)lightsource.ca

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probem with run Athena
by 康明亮 20 Jan '10

20 Jan '10

Dear Matt, Many thanks for your answer yesterday. Since I am a novice, I am now still puzzled to use this software. I just want to process some XANES data for selenium speciation identification. As attached in the annex(three samples and four references, some have analyzed for several times). When open SixPack, I can't import any file from which attached in the enclosure. I don't know whether it is the problem with the format of the data. Thus, I thought probably I need to open the Athena, while it prompted: Cann't execute Grnd.exe.... Sincerely wish to obtain guidance from you. Kind regards Mingliang

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Re: [Ifeffit] consultation
by Jens Kruse 20 Jan '10

20 Jan '10

Hi, I had a similar problem. In my case it was name of the Folder which included the letter "ö". After I changed the name, I had no problem anymore to open the file. In your case I think the "Chinese" letters are the problem. Just change the Folder name, maybe It helps. jens Am 20.01.2010 16:31, schrieb ifeffit-request(a)millenia.cars.aps.anl.gov: > 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. consultation (???) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 20 Jan 2010 23:31:12 +0800 (CST) > From: ???<kangml(a)163.com> > To: "XAFS Analysis using Ifeffit"<ifeffit(a)millenia.cars.aps.anl.gov> > Subject: [Ifeffit] consultation > Message-ID: > <16030032.1199091264001472057.JavaMail.coremail(a)app188.163.com> > Content-Type: text/plain; charset="gbk" > > Dear, I want to consult why I can not open the XANES raw data(like the attached file Na2SeO3.dat) by Athena on my laptop(Windows system). It prompt that : coulldn't read...(See the attached picture. file). Wish to obtain help from you.Thanks very muchBest wishesMingliang >

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(no subject)
by JeongEunSuk 19 Jan '10

19 Jan '10

Hi all I have a question for XANES of Zinc compounds. It is known that the pre-edge for Zinc k-edge generally doesnt exist because 3d state of Zinc atom is occupied. However, I got it from ZnMgO with wurtzite structure. 4 oxygen in first shell and 12 zinc in second shell are located around Absorbing atom, Zinc in wurtzite structure. And then I know that some Mg atoms are replaced on zinc site from EXAFS. I wonder the reason for the appearence of pre-edge. Is it structural problem? or substituted Mg? If anybody know reference papers for pre-edge of zinc K-edge, Please answer me. _________________________________________________________________ 새로운 Windows 7: 여러분에게 맞는 최상의 PC를 찾으세요. 자세히 보기. http://windows.microsoft.com/shop

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Re: [Ifeffit] Compiler cannot handle complex function properly
by Ying Zou 15 Jan '10

15 Jan '10

Dear all, One colleague of mine brought up this to my attention. He tried a simple Fourier transformation C code on different machines (PowerPC based MAC G4, Intel based MAC G5, and PCs). The computations yield different results, sometimes on the third significant place. In his Fourier transformation implementation, a standard complex function is called. On MAC boxes, he used GNU C compiler; on PC, MS visual C compiler was used. I have done a little web survey on this issue, it seems that this was reported by others, too; there have been suggestions that it is much more reliable to handle real or imaginary part separately. Since in the Fourier transformation for EXAFS function, complex functions have to be handled too. One thing I would like to know from our Ifeffit Gurus: Are the real and imaginary parts of EXAFS functions been handled separately? Thanks for your attention! Best, Ying ========================== Dr. Ying Zou Research Associate, Physics/UWM 1900 E. Kenwood Blvd. Milwaukee, WI 53217 ==========================

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Job Posting: Post-Doc postion at Missouri State Univ, Material in Extreme Conditions
by Matt Newville 15 Jan '10

15 Jan '10

Hi Folks, Prof. Robert Mayanovic at Missouri Sate University is searching for a post-doctoral associate to work on materials in extreme conditions. More details are at http://xafs.org/Jobs --Matt

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Fwd: regading feff input file of sorbed species
by Bruce Ravel 12 Jan '10

12 Jan '10

Hi everyone, Below is an email I received this morning. I thought I would pass it along to the mailing list. I know that some of you work on projects very close to this fellow's question and thought he would benefit by the wisdom of the masses. Hi Sumit, A few pointers: * There is a wealth of information about Feff and XAFS analysis at http://xafs.org * I strongly encourage you to join and follow this mailing list. I explain the many benefits of the mailing list and offer some advice on using it effectively at this page: http://cars9.uchicago.edu/ifeffit/BruceRavel/FormLetters/HelpRequest As for your question -- there are a number of approaches to the problem of sorbed species that have been adopted by folks working both catalysis, in environmental science, and elsewhere. Obviously, sorbed species are a very important topic in many fields and XAS is very attractive for learning something about them. You would be very well served by examining the very large body of published literature on this topic. Much of that work has been done by people who read this mailing list -- I am hoping some of them will speak up. As I said, there are a number of ways to approach the problem. One fairly simple way is to run atoms on the substrate crystal and then "cut" the resulting cluster to "expose" the surface. What does this mean? The simplest case is to "expose" a (001) surface by simply deleting all atoms from the Feff input file with a positive value for the Z coordinate (assuming, of course, that the crystal is of an orthogonal type -- this "cutting" trick is a bit trickier for other cystal types). Then simply decorate the atoms list with the absorber by placing at coordinates relative to the "exposed" surface that is a plausible place to find that atom. Be sure you set the POTENTIALS list on the Feff input file correctly to account for the newly introduced absorber. This is explained in the Feff documentation and ion several places at xafs.org. Hope that helps, B --------------------------------------------------------------------------------- On Tuesday 12 January 2010, 08:21:04 am, sumitk(a)barc.gov.in wrote: Dear Sir, This is in regrad to the problem in making the FEFF input file for the Eu species sorbed on the the alumina surface. I am Sumit Kumar, Working as Reseach Scholar In Indian Nuclear Establishment. Recenrly I have carried out Eu-L3 EXAFs experiemnt at Elettra Synchrotron EXAFS beamline for delineating Eu species sorbed on alumina and other clay surfaces under different experiemntal/environmental conditions. As I understand for FeFf input file ATOMS SOFTWARE can be used, but as my species are just sorbed/chemical bonded on the surface, I can not take Eu as part of the bulk and then using ATOMS will be not be correct. I need your suggestion in this regard. Pl. suggest how to make the FEFF input file in this case. My problem is similar to one of yours paper sumitted to Geochimica Cosmochimica acta(Zn on Rutile).If you could send FEFF input file file for that work or similar other FEFF input file, it will be of much help to me. With Regards, Sumit Kumar Radiochemistry Division Bhabha Atomic Research Centre, Mumbai, India -------------------------------------------------

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Re: [Ifeffit] How to calculate F-value for XANES PCA results
by Andrew 11 Jan '10

11 Jan '10

Hi everyone, Thank you Dr. Lukens for your help! Let me see if I understand the method that was described for the F-value for the variances using the Fernandez-Garcia definition (that was previously mentioned), and please correct me if I am mistaken. The Principal Component Analysis returns the eigenvectors. Then, to calculate the F-value using the Fernandez-Garcia definition: F-value for component 1 = (variance of eigenvector 1)/ summation[(variance eigenvector 2) + (variance eigenvector 3) + . (variance eigenvector c)] F-value for component 2 = (variance of eigenvector 2)/ summation[(variance eigenvector 3) + (variance eigenvector 4) + . (variance eigenvector c)] F-value for component k = (variance of eigenvector k)/ summation[(variance of eigenvector k+1) + . + (variance of eigenvector c)] Where c is the number of components in the set. Then to calculate the probability of F corresponds to noise, then the that Excel can calculate this using the function Fdist(alpha, degree of freedom 1, degree of freedom 2). Alpha = the confidence interval desired (where 0.05 is generally used) degrees of freedom 1 = # of independent data points - 1 ((this is dependent on the resolution of the beam and Dr. Lukens provided an example calc.)) degree of freedom 2 = number of components on the denominator for the F-value being tested - 1 (i.e. for component k it would equal c-k-1-1 or c-k-2) Then, "if the probability of F less than 5%, these would be the components that you would retain." Are these equations correct? Am I using the correct equation based on the Garcia-Fernandez definition? My main misunderstanding of this was what equation to use for the F-value. Sorry for killing a dead horse, but is this definition of degree of freedom 2 correct? Thanks again for all the help and sorry if this is poorly worded, and if this is on the outer-bounds for an IFEFFIT-relevant question. Andrew

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Fwd: Athena
by Bruce Ravel 11 Jan '10

11 Jan '10

Hi Ronald, I am forwarding my response to your questions to the Ifeffit mailing list. As you will see in my attempt to answer your question, it will be useful to solicit Matt Newville's opinion. This is, of course, the great benefit of a mailing list. Issues with the software are hashed out more quickly and more efficiently when discussed in a public forum. Athena, as we all know, does not actually do much numerical work by itself. Instead it relies upon Matt's Ifeffit for all those chores (which, in turn, uses a variety of freely available numerical packages, including http://www.netlib.org/fftpack/) You ask about the Fourier transform -- Matt explains all of Ifeffit's deep, dark secrets in this part of the reference manual: http://cars9.uchicago.edu/~ifeffit/refman/node141.html I think that all of the discrepancies you are asking about are explained by two things: (1) Ifeffit zero-pads its arrays. (2) Ifeffit treats chi(k) as the real part of the orginal function which is transformed by a complex Fourier transform. Additionally, if you want to do two Foruier transforms in Athena without filtering, you need to explicitly set both FT ranges to the entire data range and you need to set the window sill widths to 0. It is unclear from what you said whether you did that. So, how worried should we be that your software and ours did not do quite the same thing? Not much, I suspect. There are some places where different conventions may have been adopted. In the end, internal consistency is probably the most important thing. Whatever set of conventions Ifeffit uses (and, thus, Athena and Artemis also use), those conventions get used when transforming both theory and data during a fit. Of course, if you still feel I am not understanding part of the problem, please let me know. As I have said many times on this mailing list, the only reason that Athena and Artemis are any good at all is because of the excellent feedback I get from the folks who read this list. Regards, B ---------- Forwarded Message ---------- Subject: Athena Date: Saturday 09 January 2010 From: "Frahm, Ronald, Prof. Dr." <frahm(a)uni-wuppertal.de> To: bravel(a)bnl.gov Dear Bruce, I hope you are doing well! Recently, I just made some calculations using Athena, comparing the results to my own analysis software. With my programs, when I Fourier transform simulated spectar, I get exactly the input amplitude and phase back after a Fourier transform pair. Perhaps I made a mistake using Athena. By importing and transforming a single shell (Feff output, chip001, Cu K-edge) I assumed from your documentation that the 5th column of the backtransform output file is the scattering phase (modulo 2*Pi) for a +...sin() EXAFS formula, and column 4 the modulus. However, Athena's phases seem to be too low by an amount very close to pi/2. Phases: ====== Values at k= 10.0: FEFF input: 37.62 [rad], Athena output: 42.39 [rad] Values at k= 15.0: FEFF input: 60.78 [rad], Athena output: 65.422 [rad] If I calculate chi with the Athena output using Chi(k) = col4 * sin(col5 + 90°) the correct chi in Athena colum 2 is reproduced (see png-files), otherwise there is a significant mismatch. I am also somewhat puzzled about the amplitude in the chi data import, and the amplitude of the resulting backtransform. Is there some scaling/weighting done automatically? Are you calculating the FT by using just the real positive part from 0 to kmax, filling the rest with zeros? The imaginary and real parts of the forward transform look significantly different from my transforms. Perhaps I missed something in your manuals, but there might be an easy explanation for my phase problem! I'd appreciate your comments. Best regards from snowy Germany Ronald ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Prof. Dr. Ronald R. Frahm Fachbereich C / Physik, Bergische Universität Wuppertal Gaußstr. 20, 42097 Wuppertal, Germany E-mail: frahm(a)uni-wuppertal.de phone: +49 202 439-3100, fax: -3101, secretary: -3102 http://hydrogen.physik.uni-wuppertal.de/index.html ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------------------------------- -- 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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