February 2016 - Ifeffit - millenia.cars.aps.anl.gov

Re: [Ifeffit] Could you please give me some information?
by Bruce Ravel 02 Feb '16

02 Feb '16

On 02/01/2016 11:58 PM, pinit wrote: > Dear Bruce, > > I am Pinit from SLRI, Thailand. I have some questions concerning the > Si-drift detector. > > Could you give me some suggestions if Si-detector can detect the > corrected Si K-edge or not? This is because I have seen a significant > EXAFS signal (higher in amplitude in FT) measured by Si-drift detector > differs from Lytle detector or ionization chambers (TM mode). Hi Pinit, Nice to hear from you. I am CCing my answer to the Ifeffit Mailing List. Someone else may have more insight into your question than I do. You should CC the list in your response. I'd probably need to know more about the sample and the nature of the measurement you made to understand why you are seeing a different signal with the Si drift detector. Normally one would expect that he EXAFS would be /attenuated/ either due to self-absorption or due to the energy dependence of the I0 detector. That you are seeing a larger EXAFS signal with the Si-drift seems surprising. One thing that occurs to me is that the Compton and elastic peaks probably overlap the Si K alpha ROI quite a bit, even extending into the EXAFS region. I would have thought that, too, would serve to attenuate the EXAFS (but maybe I am thinking about that wrongly). Perhaps it would help to show us some of the data...? B -- Bruce Ravel ------------------------------------ bravel(a)bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 535A Upton NY, 11973 Homepage: http://bruceravel.github.io/home/ Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/

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pi/2deltak
by Ritimukta Sarangi 01 Feb '16

01 Feb '16

Hello, I was recently asked about the accuracy of this formulation for obtaining EXAFS resolution and I did not have a good answer. Can someone point to a reference or explain here? Thank you for your time, Best, -Riti

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FW: Data summation - missing groups
by Godfrey, Ian 01 Feb '16

01 Feb '16

Sorry, I've just seen that this has already been reported. Ian From: Godfrey, Ian Sent: 27 January 2016 11:21 To: 'XAFS Analysis using Ifeffit' <ifeffit(a)millenia.cars.aps.anl.gov> Subject: Data summation - missing groups Dear All, When using the data summation tool in Athena (0.9.24 x64 on Win10 Pro) the first group in the group list seems to be missing from the dropdown showing the potential components of a summation (see attached screenshot). To reproduce: 1) Open attached project file and import with "select all" on the import dialogue box 2) Change to data summation window 3) Try and add the first data group (234) to the summation from the dropdown menus. (In the screenshot I've changed the default normmu(E) to mu(E), but the same behaviour is displayed in both cases.) On a related note, I'm not sure I fully understand how the data summation is different from the merge? Clearly data summation allows you more control (arbitrary weighting of groups etc.) and is intended for XANES analysis, but is it a fundamentally different procedure or just a different interface for the same thing? Thanks, Ian Ian Godfrey PhD Student, UCL/JAIST Programme Industrial Doctorate Centre in Molecular Modelling and Materials Science, Department of Chemistry, University College London, And School of Materials Science, Japan Advaned Institute of Science and Technology i.godfrey(a)ucl.ac.uk<mailto:i.godfrey@ucl.ac.uk> i.godfrey(a)jaist.ac.jp<mailto:i.godfrey@jaist.ac.jp> 02076 794864

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