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

Re: Ifeffit Digest, Vol 6, Issue 6
by Grant Bunker 19 Aug '03

19 Aug '03

Scott - You could bridge the gap by using VirtualPC until an installer is constructed. That has the added benefit that you can also run windows xp or 2000 pro and PC linux (redhat, debian) simultaneously with OSX. It makes for a very flexible system, you can run almost anything, and furthermore the actions on the PC can be controlled by applescript on the mac side. On a fast mac with lots of memory, speed is adequate for most purposes, and the more you run it the faster it gets (instruction cache). I do these things my tibook and it works fine. A dual processor G5 should really work well. best wishes - grant bunker On Tue, 19 Aug 2003 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. Decision time... (SCalvin100(a)aol.com) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 18 Aug 2003 20:31:23 EDT > From: SCalvin100(a)aol.com > Subject: [Ifeffit] Decision time... > To: ifeffit(a)millenia.cars.aps.anl.gov > Message-ID: <c5.370ac25e.2c72c9db(a)aol.com> > Content-Type: text/plain; charset="us-ascii" > > Hi all, > > I'm very pleased to see all the activity on the list regarding an IFEFFIT > installer for OS X, and I appreciate very much the thought that has gone into > this issue. Unfortunately, decision time is upon me. I need to decide within a > day or two whether to go with Macs or PCs in my new faculty position. If someone > can tell me there will be some sort of installer (either requiring Fink or > not) by September 15, I'll go with Macs. If not, I'll have to go with PCs. > > --Scott Calvin > Sarah Lawrence College >

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Decision time...
by SCalvin100＠aol.com 18 Aug '03

18 Aug '03

Hi all, I'm very pleased to see all the activity on the list regarding an IFEFFIT installer for OS X, and I appreciate very much the thought that has gone into this issue. Unfortunately, decision time is upon me. I need to decide within a day or two whether to go with Macs or PCs in my new faculty position. If someone can tell me there will be some sort of installer (either requiring Fink or not) by September 15, I'll go with Macs. If not, I'll have to go with PCs. --Scott Calvin Sarah Lawrence College

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problem on MACOSX
by Stefano Ciurli 07 Aug '03

07 Aug '03

Dear all, when i try to compile the ifeffit program, the system does not find f2c_comp and I do not know how to install it using fink. Then, if i substitute f2c with f77, I get the following error message: How do I solve this? Regards Stefano Ciurli Making all in test gcc -g -O2 -o ifftest1 ifftest1.o ../lib/libifeffit.a -L/sw/lib/pgplot -L/sw/src/root-pgplot-5.2-5/sw/lib/pgplot -lpgplot -L/sw/lib -lpng -lz -L/usr/X11R6/lib -lX11 -framework Foundation -framework AppKit -lm ld: warning -L: directory name (/sw/src/root-pgplot-5.2-5/sw/lib/pgplot) does not exist ld: Undefined symbols: _main _do_lio _e_wsle _s_cmp _s_copy _s_stop _s_wsle _do_fio _e_rsfi _e_wsfi _i_indx _s_cat _s_rsfi _s_wsfi _e_wsfe _s_wsfe _G77_getenv_0 _f_inqu _e_rsfe _s_rsfe _z_exp _f_clos _f_open _e_rsle _s_rsle _z_sqrt _do_uio _e_rsue _s_rsue make[3]: *** [ifftest1] Error 1 make[2]: *** [all-recursive] Error 1 make[1]: *** [all-recursive] Error 1 make: *** [all-recursive-am] Error 2 -- ____________________________________________ Stefano Ciurli Professor of Chemistry Department of Agro-Environmental Science and Technology University of Bologna Via Fanin 40 I-40127 Bologna Italy Phone: +39-051-209-6204 Fax: +39-051-209-6203

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Re: [Ifeffit] What differences are there between Athena and AUTOBK backgrounds?
by SCalvin100＠aol.com 06 Aug '03

06 Aug '03

Thanks, Matt. I hadn't realized I wasn't using the most recent version of AUTOBK. Of course, now I'll be using IFEFFIT (via Athena), so it doesn't matter... --Scott

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[Ifeffit] What differences are there between Athena and AUTOBK backgrounds?
by Scott Calvin 05 Aug '03

05 Aug '03

Hi all, Today I tried making Athena perform exactly the same background subtraction as AUTOBK 2.61 (all parameters the same, working on the same data, using the same theoretical standard, etc.). I then let FEFFIT take the chi(k) data for each and perform a Fourier transform. When I did this, AUTOBK would always generate a very low r (< 0.2 angstroms) peak of significant amplitude that was nearly absent in the Athena background. There were other subtle differences as well, but that one stood out. Of course, a peak that low in r should have no effect on the fit, but it made me curious--were substantive changes in the background subtraction algorithm made when AUTOBK was incorporated into IFEFFIT? --Scott Calvin Sarah Lawrence College

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Phase Correction using IFEFFIT
by Ian Drake 04 Aug '03

04 Aug '03

Hi Matt and XAFS community I am interested in the details of how IFEFFIT handles phase correction. I asked a similar question in April, but have only now begun to address its use in my work. In your response to my April question, you described how to do a central atom phase shift (without a FEFF path) and a combined central-atom and scattering-atom phase-shift (using a particular FEFF path). In the case of the combined central-atom/scattering-atom phase-shift, is the Chi(k) multiplied by exp(i*Phase(Central-atom)) and exp(i*Phase(scatterer)) before FFT? If this is true, how can I correct for the scattering atom phase shift "only" as has been described by Lee and Beni (Phys. Rev.B, 15, 1977, pg 2862) and Vaarkamp (Cat. Today, 39, (1998), pg 271). At this time, my particular interest is in attempting to identify clearly next-nearest neighbors in the RSF before attempting to do fitting. It is my hope that a positive identification of the next-nearest neighbor by means of IM analysis/ and or k-weighting will add validity to my final fitting results. Thank you for your help, Ian Drake

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phase corrections
by Grant Bunker 04 Aug '03

04 Aug '03

Following Bruce's commentary - it is indeed true that if you have sufficiently heavy backscatterer (think Au or Pt, or even Ag/Pd) the modulations in the backscattering phase and amplitude will mess up your transform peaks, as Ian suggests. Basically you get "sideband modulation" of your transform peaks. To get rid of them you need to not only do a phase correction, but also an amplitude correction (divide out the wiggles). I thinkd oing one without the other doesn't actually make a lot of sense since they are related (because the real and imaginary parts are related by kramers-kronig relation the phase and amplitude are connected). Obviously this is not very difficult to do - I put it into the VAX version of the UW programs in 1985 but that was dropped from the simplified UW/NRL version later. Short term, it would be very easy to do by exporting from ifeffit and using any data massaging program that knows complex numbers. thanks - grant On Mon, 4 Aug 2003 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: Phase Correction using IFEFFIT (Bruce Ravel) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 4 Aug 2003 09:56:14 -0400 > From: Bruce Ravel <ravel(a)phys.washington.edu> > Subject: Re: [Ifeffit] Phase Correction using IFEFFIT > To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> > Message-ID: <200308040956.14156.ravel(a)phys.washington.edu> > Content-Type: text/plain; charset="iso-8859-1" > > On Saturday 02 August 2003 04:32 pm, Ian Drake wrote: > > At this time, my particular interest is in attempting to identify clearly > > next-nearest neighbors in the RSF before attempting to do fitting. It is > > my hope that a positive identification of the next-nearest neighbor by > > means of IM analysis/ and or k-weighting will add validity to my final > > fitting results. > > Well... I don't know what an "RSF" is or what "IM analysis" is, but I > think I can suggest a way to isolate the scattering atom phase shift > in a way that requires only a small amount of work and can be used > with either ifeffit or artemis as they exist today. > > The second column of the feffNNNN.dat file is the central atom phase > shift. The third and fourth are the scattering atoms magnitude and > phase. Copy your feffNNNN.dat file of interest to another name, say > feff_next_neighbor_no_caps.dat. Edit the new file, replacing the > second column with zeros. Read this into ifeffit or artemis and use > it as the path for phase correction. In artemis, this is done in the > data view using the pull down menu labeled "Path to use for phase > correction". Obviously, you should choose your edited path. In > artemis, you may need to set the amplitude for this path to zero so > that it doesn't really get used in a fit. > > That said, it's not clear to me how phase correction will really do > what you seem to want. It seem unlikely to me that the signal beyond > the first shell will magically become clear simply by doing phase > correction. If the signal is a superposition of various scatterers > before phase correction, it will still be a superposition of various > scatterers afterwards. Removing the scattering atom phase shift does > not affect the terms in the EXAFS equation that make peaks in a > Fourier transform broad, nor does it magically separate signals which > contribute similar Fourier components. Understanding how various > paths contribute similar Fourier components is the reason that Artemis > allows you to easily overplot data with the Fourier transforms of > various paths. Then you can inspect the contributions from each path > before setting up your fitting model. But if playing tricks with > phase correction helps *you*, then great! That is why Artemis allows > you to do this. > > B > > > > -- > Bruce Ravel ----------------------------------- ravel(a)phys.washington.edu > Code 6134, Building 3, Room 222 > Naval Research Laboratory phone: (1) 202 767 5947 > Washington DC 20375, USA fax: (1) 202 767 1697 > > NRL Synchrotron Radiation Consortium (NRL-SRC) > Beamlines X11a, X11b, X23b, X24c, U4b > National Synchrotron Light Source > Brookhaven National Laboratory, Upton, NY 11973 > > My homepage: http://feff.phys.washington.edu/~ravel > EXAFS software: http://feff.phys.washington.edu/~ravel/software/exafs/ > > > ------------------------------ > > _______________________________________________ > Ifeffit mailing list > Ifeffit(a)millenia.cars.aps.anl.gov > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > > > End of Ifeffit Digest, Vol 6, Issue 2 > ************************************* >

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IFEFFIT and PGPLOT on linux
by Kelly, Shelly D. 31 Jul '03

31 Jul '03

Hi Matt, Yesterday, I installed PGPLOT and IFEFFIT from the tar ball on your web page on a clean (no previous installation of any of the XAFS software) Red Hat linux box. I used your script to install PGPLOT and was pleased that it worked just as expected. I had one small issue. When I tried to 'make' IFEFFIT, I got an error message saying that there was nothing for make to do. I realized that the configure step for IFEFFIT was writing out a Makefile but that the current directory had both a makefile and a Makefile. One makefile with a lowercase m and the other with a capital case M. So I removed the makefile and then IFEFFIT installed properly. Then I used the Horae script to install Ravel-ware, without any trouble. Overall the installation went really well...Good going. Shelly Kelly

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Re: [Ifeffit] Self-Absorption Corrections
by Francois Farges 30 Jul '03

30 Jul '03

hi all, Here is a gif of Nb2O5 at Nb K-edge and TiO2 at Ti K-edge. Both collected withb same geometry and detectors and same BL (SSRL 11-2). Fluo was collected at 90° to the beam (while transmission data was collected on the exact same sample). both spectra are normalized. Is there not any remaining self-absorption in the fluo spectrum for Nb2O5, despite data collected at 90° ?? (while TiO2 sounds fine, as Troeger predicted ?). thank for your expertise ! -- Francois FARGES Laboratoire des Géomatériaux Université de Marne la Vallée 5 Bd Descartes-Champs S/Marne 77454 Marne la Vallée cedex 2 TEL: 01 49 32 90 57 from outside France: +33 1 49 32 90 57 FAX: 01 49 32 91 37 from outside France: +33 1 49 32 91 37

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Self-Absorption Corrections, Wavelet Transforms
by Matt Newville 29 Jul '03

29 Jul '03

Hi Everyone, There were several conversations around the XAFS 12 conference on self-absorption corrections for EXAFS. It would be nice to add such corrections (and others, like for deadtime corrections) to Ifeffit. Corwin Booth (at LBL lab, Berkeley) presented a very nice procedure for making these corrections for EXAFS at the conference, improving the work of L. Troger, et al from the mid 1990's. Corwin just sent me the Fortran source code for his program so that it might be included in Ifeffit, and is letting me pass it on. I put the source code (with a Unix Makefile and some instructions) at http://cars.uchicago.edu/ifeffit/contrib/sabcor.tar.gz with a README at http://cars.uchicago.edu/ifeffit/contrib/README.SABCOR I'd be interested in hearing others opinions on this topic, and whether this should be included in Ifeffit. A self-absorption correction that worked better for XANES would be useful too. If you've thought about self-absorption corrections or have some data affected by self-absorption corrections, please check out Corwin's code and let us know what you think of this. Speaking of things to check out, Francois Farges recently created a web page discussingCauchy Wavelet transforms of EXAFS data at http://www.univ-mlv.fr/~farges/wav/ The site includes MATLAB code and references. These transforms are very interesting and I recommend checking out this stuff. There was also a recent email from Harald Funke sent to many people about a different code for Wavelet transforms. If I get permission from Harald, I'll post these codes too. Related to all this, I added a 'Contributions' page to the Ifeffit Web Pages, for "contributions and/or things to consider for XAFS analysis and Ifeffit". Currently, this has links to Corwin's self-absorption correction code, and Francois' Wavelet web page. If anyone has any suggestions for other things to add, let me know. Thanks, --Matt

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