January 2009 - Ifeffit - millenia.cars.aps.anl.gov

Artemis parameters
by abhijeet gaur 29 Jan '09

29 Jan '09

Hi I am fitting a copper foil whose data is taken at room temperature. So do I need to change the guess value of parameters enot, ss,amp, delr to some other value or I should take them as the default guess value. Also what should be the ideal fitting range in R for the copper foil. With thanks Abhijeet

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uncertainty in linear combination analysis
by Pushan Shah 29 Jan '09

29 Jan '09

Hello Everyone! How can I estimate an uncertainty in linear combination analysis and calculate them in percentage error? Many thanks, Pushan

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about Farrel Lytle data of Na2WO4.2H2O
by Yordy Licea Fonseca 28 Jan '09

28 Jan '09

Hi, Sorry, I could not find enough information. Would any of you tell me, please, how is the EXAFS data tabulated in Farrel Lytle data base? The first column is the energy, what about others? I would like to obtain the absorption coefficient vs energy from this file: http://ixs.csrri.iit.edu/data/Farrel_Lytle_data/RAW/W/wna.095 Best wishes, -- Yordy E. Licea Fonseca Departamento de Físico-Química Instituto de Química-IQ/UFRJ Laboratório de Catálise Heterogênea Rio de Janeiro, RJ, CEP 21.949-909 Brasil Email: yliceafonseca(a)gmail.com

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Trouble with fitting with Artemis
by Juraci A. Sampaio 28 Jan '09

28 Jan '09

Hi there!I'm getting the following message when I try to fit my data:WARNING. The following variables had no effect on the fit: !! >> amp !! >> enot !! >> delr !! >> ss The data that I am trying to fit is the Cu metal example that come with the iffefit package. I am running Artemis on a Mac, OSX 10.4.11.I could run the fitting on a mac OSX 10.5 and it worked fine. I reinstall the IXAFS package but it didn't work.I am wondering what could be wrong with my machine/software?Thanks a lot.Juraci Sampaio _________________________________________________________________ Confira vídeos com notícias do NY Times, gols direto do Lance, videocassetadas e muito mais no MSN Video! http://video.msn.com/?mkt=pt-br

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EXAFS data
by abhijeet gaur 28 Jan '09

28 Jan '09

Hi We have Farell Lytle type data. When we put that into ATHENA we get the Energy curve. But we are not able to extract that Energy converted data from ATHENA . We tried to import the data in ORIGIN but we could not do so though the graph was imported.So if there is any way to extract the data please let us know. Thanks Abhijeet

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Energy shift
by Eugenio Otal 27 Jan '09

27 Jan '09

Hi all, I finished simulations of Er(OH)3, ErO(OH) and Er2O3, when I compared the spectras with the samples and I found a shift in energy equal to 5.5 eV.Even between the meassured and calculated spectra of Er2O3, which was previously calibrated with a niquel film standard. Is this shift part of the bussines? Thanks, euG

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Re: [Ifeffit] Cumulant expansion fittings
by Patrick Kluth 27 Jan '09

27 Jan '09

Hi Matt, >Of course, XAFS *is* a one-dimensional probe, not a three-dimensional one. >At least ignoring for the moment the angular dependence of multiple >scattering, XAFS is sensitive to g(r) only. Sadly, this is sometimes >forgotten in the literature, and one sees attempts to distinguish >"sigma^2_perpendicular" and "sigma^2_parallel", which is a good sign of a >paper that is complete nonsense. I don`t agree with you in this point. To my understanding, because EXAFS is a one-dimensional probe and it measures the average over instantaneous inter-atomic distances, it is only sensitive to the motion relative to each other along the bond-direction - and thus measures sigma^2_parallel. Combined with XRD which measures the the atomic motion averaged over all directions one can then extract a "sigma^2_perpendicular". If we are talking about the same literature this point is well elaborated in there and I don`t think it is nonsense. Please correct me if I am wrong. Cheers, Patrick --------------------------------------------------------------------- Dr. Patrick Kluth Fellow, ARC Australian Research Fellow Department of Electronic Materials Engineering Research School of Physics and Engineering The Australian National University Canberra, ACT 0200 AUSTRALIA Phone: +61 2 6125 0358 Fax: +61 2 6125 0511 Mobile: +61 408 66 31 04 Email: patrick.kluth(a)anu.edu.au http://www.rsphysse.anu.edu.au/eme ---------------------------------------------------------------------

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small-screen version of Athena document
by Bruce Ravel 26 Jan '09

26 Jan '09

Hi, There is now a version of the Athena User's Guide which is intended for small-screen device (like my the new toy I got this weekend). Here is the URL: http://cars9.uchicago.edu/~ravel/software/doc/Athena/mobile/ This is very similar to the normal html version of the User's Guide, except for a few changes in layout to make it work better on a small screen. The mobile version is not perfect yet, but it is much more legible than the normal version. I have tested it mostly in Explorer on Windows Mobile 6. (I have also tested it under Opera for mobile devices, but I am not happy with how either version gets displayed there.) Hopefully this will be helpful for someone. Regards, B -- 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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Query regarding measurement uncertainity
by Bindu R. 26 Jan '09

26 Jan '09

Dear all, I have one doubt regarding the measurement uncertainty in R- space (εR). In the manual it is written that εR is evaluated from the rms value of FT in the range 15-20 Å. My doubt is..... In case the FT in R-space does not extend up to the range mentioned above, then how does the fitting program choose the value of εR? Please clarify me this. With best regardsBIndu Dr.Bindu R. Visiting Fellow BG-37 DCMP&MS Tata Institute of Fundamental Research Homi Bhabha Road Colaba Mumbai-400 005 India Contact Number Lab- 022-2278 2256, 022-2278 2671 Mobile-919892536830 Add more friends to your messenger and enjoy! Go to http://messenger.yahoo.com/invite/

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FEFF calculations for Zeolite
by Feng Wang 23 Jan '09

23 Jan '09

Hi all, My colleague is trying to load Pt into the cages of the zeolite_LTA. It seems the crystallinity was destroyed with small Pt loading (<3%weight)according to the X-ray and e-beam diffraction. I suppose this is not sth new, but it looks intereting to understand the local structural structure with Pt loading, maybe by x-ray absorption or energy loss near-edge structure. Do you know how I should get the FEFF input file for this complex? Also please let me know if you have any relevant reports or your own results for exchange, I will appreciate that, thank you. Sincerely, Feng ==================================== National Institute for Nanotechnology 11421 Saskatachewan Drive Edmonton, Canada T6G 2M9

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