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

compiling feff 9
by Eugenio Otal 11 Feb '11

11 Feb '11

Hello, I am trying to compile the feff9 with ifort linux compiler but I find that the code is split in more than one file unlike feff84 that is only one file, feff84.f. I read the manual and I cannot find any help in feff9 manual, in feff84 manual there are more information but it is also not so useful. Would you help me to know how to compile the code with all this files. Kind Regards, euG 8<- - - - - - 8<- - - - - - 8<- - - - - - 8<- - - - - - Dr. Eugenio H. Otal Solid State Chemistry and Catalysis Laboratory, Empa - Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, CH-8600 Duebendorf, Switzerland, Tel +41 44 823 41 31, Fax +41 44 823 40 19, eugenio.otal(a)empa.ch, www.empa.ch/abt131,

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Reminder: NASCCSC Abstracts Deadline
by Carlo Segre 08 Feb '11

08 Feb '11

Hello All: In case you had not seen this notice, the Second Annual North american Core Shell Spectroscopy Conference will be held jointly with the Denver X-ray Conference in Colorado Springs this on August 1-5. This years conference will have special sessions on catalysis and 5f electron systems. Abstract sumissions will be open probably until March 1, 2011. More information can be found at http://www.dxcicdd.com/cssc/ Hope to see you there! Carlo -- Carlo U. Segre -- Professor of Physics Associate Dean for Graduate Admissions, Graduate College Illinois Institute of Technology Voice: 312.567.3498 Fax: 312.567.3494 segre(a)iit.edu http://www.iit.edu/~segre segre(a)debian.org

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R dependence of S02
by Scott Calvin 05 Feb '11

05 Feb '11

Hi all, I've been pondering how much R dependence we should expect to see in S02; that is, how much R dependence is shown by intrinsic losses. I've looked at quite a bit of the literature, not to mention old threads from this mailing list. One recent (2002) reference is this one by Campbell et al.: http://prb.aps.org/pdf/PRB/v65/i6/e064107 My understanding is that S02 is intended to account for intrinsic losses; that is, those that are determined when the core hole forms. Extrinsic losses, such as inelastic scattering of the photoelectron and the effect of the core-hole lifetime, are accounted for by a mean free path term. The mathematics of how ifeffit implements this are here: http://cars9.uchicago.edu/~newville/feffit/feffit.ps Intrinsic losses are dependent on k for at least two reasons. One is that the cross-section of the intrinsic effects themselves depends on the energy of the incident x-ray. This is evident if one thinks in terms of shake-up and shake-off events. But another reason is that shake-up and shake-off events rob some energy from the primary photoelectron. At low k, ten or twenty electron volts can alter the phase of the primary photoelectron significantly, and thus shake-up and shake-off events will tend to cancel each other out. But at high k, the energy robbed from the photoelectron is less significant, because the EXAFS oscillations are more spread out in energy. Thus, shake-up and shake-off events, while still occurring, will not suppress the EXAFS amplitude as much at high k. S02 therefore gradually rises through most of the EXAFS region to reach a limiting value of 1 well above the top of the EXAFS region. The latter effect--the fact that removing a specified amount of energy from the primary photoelectron has less of an effect at high k than at low--also implies an R dependence. Low R oscillations are further apart in energy than high R oscillations, and thus over a specified k range low R oscillations should be less affected. In other words, S02 should show a modest decrease with increasing R over typical EXAFS ranges. Some papers, in particular those with John Rehr as an author, confirm that S02 should have an R dependence, but don't discuss the implications much. While ifeffit allows for floating ei, a parameter related to the mean free path, as I understand it that will still give a damping of the amplitude that is exponential in R. It seems to me that the S02 dependence on R, in contrast, is likely to be more gentle. Why is this important? Several authors, including myself, have analyzed crystallite size and/ or morphology by comparing the coordination number of successive scattering shells. This is potentially much more accurate than just finding the first-shell coordination number, because it is independent of any amplitude effects that are independent of R, such as normalization errors and many experimental effects. Errors in the mean free path are a bit more significant, but the exponential dependence of the mean free path gives it a very different shape than effects from size and morphology. But an R-dependence of S02 would be troubling, as the functional form might look a bit more like a size effect. So one question is this: does anyone have an order-of-magnitude estimate of how much R dependence to expect in S02 over the EXAFS range? If over a range of 2 to 6 angstroms S02 changed by even a few percent, that could have a significant effect on the kind of size analyses I mentioned in the preceding paragraph. Of course, another question is if I've completely blown it anywhere in my discussion above; I've just been puzzling this out over the last few days! --Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory

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EXAFS fitting method
by Abhijeet Gaur 30 Jan '11

30 Jan '11

Hi all, As I understand, the EXAFS fitting procedure using Artemis, for generating a theoretical model requires the crystal structure parameter like space group, cell parameters and *specially* *atom coordinates* etc. For this we have to perform XRD measurements of single crystals of the samples. I have some questions (1) In case we dont have the XRD data of a sample then how can the EXAFS analysis be done of that sample? (2) If we have already performed the XRD on the sample then by doing EXAFS what additional information are we getting ? (3) If the answer to the first question is that - *use the crystal structure of a * * similar sample,* then what are the conditions under which we can use the known crystal structure of one sample for other samples ? Thanks in advance Abhijeet Gaur

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Fwd: Horae-70 installation problem
by Bruce Ravel 18 Jan '11

18 Jan '11

Hi all, Has anyone here ever used security enhanced linux? I got the following bug report from an SELinux user which includes an error message from one of SELinux security systems. Never having used SELinux myself, I don't quite understand the problem Dr. Pan is observing once he uses chcon to change the security state of the ifeffit library. And I don't have a machine on which to explore this problem. I am hoping someone here might be more knowledgable than I. If anyone can offer any assistance to Dr. Pan, that would be great. Thanks, B ---------- Forwarded Message ---------- Subject: Horae-70 installation problem Date: Saturday, January 15, 2011, 01:34:29 am From: Guoqiang PAN <gqpan(a)ustc.edu.cn> To: Bruce Ravel <bravel(a)bnl.gov> Dear Dr. Ravel Hi, thank you very much for the horae-70 for artemis, athema and hephaestus XAFS software. Due to the detail for the installation, I have installed in my PC linux of Fedora Core 10. When artemis has been installed, it was failed to run correctly. There is a detailed explanation of it in the attachment. I fixed it using chcon -t textrel_shlib_t '/usr/local/lib/perl5/site_perl/5.10.1/i686-linux/auto/Ifeffit/Ifeffit.so' Afterwards, it seems work, but the data in the interface panel could not be changed,please refer to the attached snapshot pictures. My system information as follows: [gqpan@localhost horae-070]$ uname -a Linux localhost.localdomain 2.6.27.5-117.fc10.i686 #1 SMP Tue Nov 18 12:19:59 EST 2008 i686 i686 i386 GNU/Linux Thank you for your help! Best regards! Guoqiang PAN National synchrotron Radiation Laboratory University of Science & Technology of China ----------------------------------------- -- 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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Liquid gold-Latex suspension measurements
by Julian Kaiser 14 Jan '11

14 Jan '11

Dear Colleagues, I would like to measure some Gold-Nanoparticles that are embedded in a kind of polymer-matrix consisting of a polystyrene-core and some polyelectrolyte-chains. The total amount of gold in the suspension will be 0.025-0.05 percent by weight. The idea is to place the sample in a polystyrene cuvette with approximately 1 mm diameter (sample) and (2x) 1 mm (polystyrene). We've tried once to measure in transmission mode, where we had some problems maybe due to the absorption of water and polystyrene. Measurements in fluorescence mode might also cause problems by self-absorption and the absorption of the polystyrene again. Does anybody have good experience with liquid measurements of diluted samples? Best regards, Julian ========================================= Julian Kaiser Helmholtz-Zentrum Berlin für Materialien und Energie Hahn-Meitner-Platz 1, D-14109 Berlin Tel. +49 30 8062 - 43029 Mail: Julian.Kaiser(a)helmholtz-berlin.de ========================================= Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V Vorsitzender des Aufsichtsrats: Prof. Dr. Dr. h.c. mult. Joachim Treusch Stellvertretende Vorsitzende: Dr. Beatrix Vierkorn-Rudolph Geschäftsführer: Prof. Dr. Anke Rita Kaysser-Pyzalla, Prof. Dr. Dr. h.c. Wolfgang Eberhardt, Dr. Ulrich Breuer Sitz der Gesellschaft: Berlin Handelsregister: AG Charlottenburg, 89 HRB 5583 =========================================

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error
by JeongEunSuk 12 Jan '11

12 Jan '11

Hi all I fitted ZnMgO to know whether Mg is sited on Zn position. the method of fitting as following; 1st : to fit with some Mg located on Zn site. 2nd: to fit with some Mg which position is different from Zn cite The parameters for Mg like bonding length, disorder and others were set. When I was fitting, there are only 8 parameters in both two method. So that independent data point and variables are same. Both 1st and 2nd had same R-factor but reduced chi-square of 1st was lager than that of 2nd. It has been known that R-factor is independent of error( uncertainty in the measurement) but reduced chi-squrare is inverse proportional to error^2. So I think that same R-factor and different reduced chi-square for two method mean the fittings of two method are not different, but error used in reduced chi-square is different. I want to know how the error used in reduced chi-square is decided in FEFFIT code.

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Re: [Ifeffit] Cadmium K-edge
by Alan Du 12 Jan '11

12 Jan '11

Hi Bhoopesh and Scott, I should have given a description of my project. Yes Scott, the work is to investigate the binding mechanisms of aqueous cadmium onto sodium titanate nanotubes. Spectrum of Sample 1 and 2 obtained from merging 9 scans and 4 scans, respectively. A quick check in Athena and, indeed, the white line of Samples are higher than CdO. I'm not sure the reason behind it though. It is likely that cadmium binds to the surface of substrate rather than inside the bulk. The lack of distinct peaks after 1.8 Å means that there are not many scatters around the absorber? Bhoopesh, as requested, I have attached the real part of FT ( http://img585.imageshack.us/i/ftreal.jpg/) I haven't got a chance to interpret them. >From preliminary fitting of Sample 1, the major and minor peaks at 1.8 and 2.3 Å could be described by a Cd-O path (CdO). This interests me because Sample 2 does not have a peak at 2.3 Å, meaning there is another single scattering path for Sample 2?. The peaks at 3 Å were fitted with Cd-Ti path (CdTiO3). No multiple scattering paths used. The best fit goes something like this: **************************************************************************** Independent points = 13.166992187 Number of variables = 8.000000000 Chi-square = 1534.709946959 Reduced Chi-square = 297.021921317 R-factor = 0.000128095 Measurement uncertainty (k) = 0.000060423 Measurement uncertainty (R) = 0.004455442 Number of data sets = 1.000000000 Guess parameters +/- uncertainties (initial guess): amp = 0.9242390 +/- 0.0509920 (1.0000) enot = 1.3950420 +/- 0.5425380 (0.0000) delr = -0.0872060 +/- 0.0051060 (0.0000) ss = 0.0113250 +/- 0.0008480 (0.0030) amp_2 = 0.2441320 +/- 0.1905250 (1.0000) enot_2 = 22.5261260 +/- 4.5990590 (0.0000) delr_2 = 0.2510860 +/- 0.0719080 (0.0000) ss_2 = 0.0274690 +/- 0.0128040 (0.0030) Correlations between variables: amp_2 and ss_2 --> 0.9342 enot_2 and delr_2 --> 0.9133 amp and ss --> 0.8865 enot and delr --> 0.8632 amp_2 and delr_2 --> 0.3040 delr_2 and ss_2 --> 0.2888 All other correlations are below 0.25 k-range = 2.000 - 9.000 dk = 1.000 k-window = hanning k-weight = 3 R-range = 1.000 - 4.000 dR = 0.000 R-window = hanning fitting space = R background function = none phase correction = none R-factor for this data set = 0.00270 *********************************************************************************** The above enot_2 is on the high side. I am not entirely familiar with the parameters yet. Are there other parameters I should worry about? Cheers, Alan J. DU Nanyang Technological University, Singapore

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sample preparation for liquid samples
by Polzer, Frank 11 Jan '11

11 Jan '11

Dear all, I would like to measure manganese oxide nanoparticles at the Mn K edge. The nanoparticles are affixed to polystyrene latex carrier particles (PS) and the whole composite material (MnO2@PS with ca. 5 m-% MnO2 in the composite) is dispersed in water. Therefore we consider measuring the composite material in the dried state as a powder as well as in the dispersed state in water. The sample preparation for powders to me is quite straight forward, but I would really appreciate if somebody could share his experience with sample preparation and measurements of liquid samples. I think that aqueous samples are best measured in the fluorescence mode. That's why I am concerned of problems like self-absorption and so on. Can anybody tell my what is a good concentration range to overcome effects like self-absorption and how to get good fluorescence data in general? And what kind of sampler holder or materials (cuvettes, etc.) are best suited for aqueous samples? I am looking forward to receiving some helpful replies! Cheers, Frank Dipl. Chem. Frank Polzer F-I2 - Soft Matter and Functional Materials Helmholtzzentrum Berlin für Materialien und Energie Lise-Meitner-Campus Hahn-Meitner-Platz 1 14109 - Berlin Tel.: +49 30 8062-43830 Fax: +49 30 8062-42308 frank.polzer(a)helmholtz-berlin.de<mailto:frank.polzer@helmholtz-berlin.de> Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V Vorsitzender des Aufsichtsrates: Prof. Dr. Dr. h.c. mult. Joachim Treusch, Stellvertretende Vorsitzende: Dr. Beatrix Vierkorn-Rudolph Geschäftsführer: Prof. Dr. Anke Kaysser-Pyzalla, Prof. Dr. Dr. h.c. Wolfgang Eberhardt, Dr. Ulrich Breuer Sitz Berlin, AG Charlottenburg, 89 HRB 5583 ________________________________ Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V Aufsichtsrat: Vorsitzender Prof. Dr. Dr. h.c. mult. Joachim Treusch, stv. Vorsitzende Dr. Beatrix Vierkorn- Rudolph Geschäftsführer: Prof. Dr. Anke Rita Kaysser-Pyzalla, Prof. Dr. Dr. h.c. Wolfgang Eberhardt, Dr. Ulrich Breuer Sitz Berlin, AG Charlottenburg, 89 HRB 5583 Postadresse: Hahn-Meitner-Platz 1 D-14109 Berlin http://www.helmholtz-berlin.de

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Re: [Ifeffit] Athena crash during LCA
by Scott Calvin 08 Jan '11

08 Jan '11

Hi Matt and Jeff, I just upgraded to 0.8.061, and it works in that version, so apparently whatever the bug was has been fixed. Thanks for checking it out for me! --Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory On Jan 8, 2011, at 7:08 AM, Matt Newville wrote: > Hi Scott, > > Like for Jeff, the chi(k) LCA fit works for me with Athea 0.8.061 on > OSX 10.6. If I had to make a guess or recommendation for something > to try it would be this: > > Standard2 extends to pretty far out in K (>20Ang^-1) and Standard2 is > pretty glitchy beyond 12Ang^-1 or so. You might try truncating the > data and/or removing the obvious glitches before doing the background > subtraction and LCA fit. > Again, that's a guess. > > Does the latest iXAFS3 not work for you on 10.5.8? I haven't tried > it, but the intention was that it would work on 10.5. > > --Matt >

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Athena crash during LCA
by Scott Calvin 08 Jan '11

08 Jan '11

Hi all, Athena has been crashing for me during one particular linear combination analysis, and I'm wondering if any of you have an explanation. A project file which demonstrates the problem is attached. I am using Athena 0.8.054 with ifeffit 1.2.10 on a MacBook Pro using OS 10.5.8. The behavior can be seen by trying to fit the Data group by using a linear combination of Standard 1 and Standard 2 in chi(k). It gets as far as "plotting in k-space from group 'Data'...done!' and then hangs, with the watch icon remaining indefinitely. This doesn't happen in norm(E) or deriv(E) fits, and doesn't happen when Standard 1 is not used. But Standard 1 appears to have uncorrupted chi(k) data when plotted directly. Standard 1 is from one of the XDAC lines at NSLS, as are the standards that work. I've tried saving Standard 1 and reading it in as a new group, but no luck. I've also looked at the data in Standard 1, and I don't see anything out of place, such as a place where the energy backs up. I've tried starting the chi(k) file with zero values, truncating the end values, and changing the background spline to end at the same point the data does. And it always hangs at the same point. Any ideas? I'd like to use this data for a workshop next week! --Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory

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Re: [Ifeffit] Athena crash during LCA
by Scott Calvin 08 Jan '11

08 Jan '11

Jeff--sorry, I guess my grammar got a little convoluted. It DOES work with norm(E) and deriv(E) fitting for me as well. It does NOT work with chi(k) fitting for me. --Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory On Jan 7, 2011, at 7:58 PM, Jeff Terry wrote: > Did not try really hard to work with it. > > Fitting Data as norm(E) from -20.000 to 30.000 > > Fit included 98 data points and 3 variables > R-factor = 0.000263 > chi-square = 0.04347 > reduced chi-square = 0.0004482 > > group weight > ======================================= > 2: Standard 1 1.000(0.000) > 3: Standard 2 0.455(0.000) > > > group e0 shift > ======================================= > 2: Standard 1 -0.905( 0.000) > 3: Standard 2 -0.905( 0.000) > > > > <PastedGraphic-1.pdf> > > On Jan 7, 2011, at 8:07 PM, Scott Calvin wrote: > >> Hi all, >> >> Athena has been crashing for me during one particular linear >> combination analysis, and I'm wondering if any of you have an >> explanation. A project file which demonstrates the problem is >> attached. I am using Athena 0.8.054 with ifeffit 1.2.10 on a >> MacBook Pro using OS 10.5.8. >> >> The behavior can be seen by trying to fit the Data group by using a >> linear combination of Standard 1 and Standard 2 in chi(k). It gets >> as far as "plotting in k-space from group 'Data'...done!' and then >> hangs, with the watch icon remaining indefinitely. This doesn't >> happen in norm(E) or deriv(E) fits, and doesn't happen when >> Standard 1 is not used. But Standard 1 appears to have uncorrupted >> chi(k) data when plotted directly. Standard 1 is from one of the >> XDAC lines at NSLS, as are the standards that work. >> >> I've tried saving Standard 1 and reading it in as a new group, but >> no luck. I've also looked at the data in Standard 1, and I don't >> see anything out of place, such as a place where the energy backs >> up. I've tried starting the chi(k) file with zero values, >> truncating the end values, and changing the background spline to >> end at the same point the data does. And it always hangs at the >> same point. >> >> Any ideas? I'd like to use this data for a workshop next week! >> >> --Scott Calvin >> Faculty at Sarah Lawrence College >> Currently on sabbatical at Stanford Synchrotron Radiation Laboratory >> >> <LCACrash.prj> >> _______________________________________________ >> 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] Problem with Athena
by Bruce Ravel 07 Jan '11

07 Jan '11

Hi Samer, I am CCing my response to the Ifeffit mailing list. I ask that questions about the software be directed to the mailing list rather than to me personally. The file that you attached is from the SSRL Data Collector. This is one of the formats supported by a filetype plugin. See http://cars9.uchicago.edu/~ravel/software/doc/Athena/html/import/plugin.html As explained on that page, from the "Settings" menu, select "Plugin registry", then click on the button labeled "SSRLA". Athena will then be able to import your file. If you do not have that plugin on your computer for some reason (for example, if you are running a somewhat old version of Athena), a copy can be found at http://cars9.uchicago.edu/svn/horae/trunk/lib/Ifeffit/Plugins/Filetype/Athe… Place that file in C:\Program File\Ifeffit\horae\Ifeffit\Plugins\Filetype\Athena\ if you are a windows user or in $HOME/.horae/Ifeffit/Plugins/Filetype/Athena/ on linux. There is a similar location on a Mac, but I don't know its path off the top of my head. B On Friday, January 07, 2011 05:46:13 am you wrote: > Dear Mr. Bruce, > > > > At first I wish you a happy new year and a very successful 2011! > > I have problem with opening the Roble files with Athena (see pleas attached > file). > > I get the following error: the file could not be read by ifeffit as data > file. > > Our Athena version is 0.8.061. > > > > Could you please help me? > > 　 > > Thanks in advance. > > > > With best wishes, > > > > Samer Amayri > __________________________________________________________________ > Dr. Samer Amayri > Institut für Kernchemie > der Universität Mainz > Fritz-Strassmann Weg 2 > D-55128 Mainz > Telefon: +496131 39-25317/25307 (Lab.) > Handy: 017621805879 > Fax-Nr. +496131 39-24510 > E-mail: amayri(a)uni-mainz.de<mailto:amayri@uni-mainz.de> -- 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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Re: [Ifeffit] Cadmium K-edge
by Scott Calvin 06 Jan '11

06 Jan '11

Hi Alan, (To the list: I discussed Alan's system a bit with him when he came to SSRL, but don't recall the details. That's why in this reply I have a little more knowledge about it than what he posted yesterday.) I suspect the peak at 2.3 A does indeed represent structure of some kind. Your k-space data for sample 1 has very little noise, so I don't think it's spurious in that sense. What strikes me about your data is that the FT's have so little structure beyond the 1.8 A peak. I don't recall exactly the nature of your system: it was cadmium loaded on to the surface of a substrate, but I don't recall what the substrate was. If it's low-Z (for example, silica), then the scattering off of whatever the oxygen is bonded to (in my example, silicon) would show up pretty weakly, and that could be the peak at 2.3 A. It's absence in sample 2 could represent the cadmium ion being less selective about what surface site it bonds to, so that the Cd-Si distance (in my example) varies and the peak washes out. That's all just an example of the kind of thing that could be responsible for what you're seeing. I agree that a good plan is to use a Cd-O structure to at least let you model the first peak. For the second peak, though, you may have to take more inspiration from the structure of the substrate than the structure of Cd-O. It's also intriguing that the white line in your sample is larger than in the CdO standard from the database. Someone with more XANES experience than I might be able to suggest why that is--something about these being bound to the surface? Is my recollection of your system correct? If so, what was the substrate? --Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory On Jan 5, 2011, at 11:23 PM, Alan Du wrote: > > Hi all, > > I processed my XAS data and compare them with standards from Farrel > Lytle Database. (http://img717.imageshack.us/i/xasw.jpg/) > > In the RSF, both sample 1 and 2 has a major peak at R = ca. 1.8 A. > sample 1 has an additional peak at R = ca. 2.3 A. I wonder if this > tiny peak is significant. > > It seems both samples has peak positions similar to those of CdO > standard, which sound logical because the cadmium will bind to the > surface oxygen of the material. > > I looking at fitting sample 1 and 2 using whatever crystallographic > info of CdO I can get my hands on. > > Wonder if the plan make sense. > > Happy new year, > Alan

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Cadmium K-edge
by Alan Du 06 Jan '11

06 Jan '11

Hi all, I processed my XAS data and compare them with standards from Farrel Lytle Database. (http://img717.imageshack.us/i/xasw.jpg/) In the RSF, both sample 1 and 2 has a major peak at R = ca. 1.8 A. sample 1 has an additional peak at R = ca. 2.3 A. I wonder if this tiny peak is significant. It seems both samples has peak positions similar to those of CdO standard, which sound logical because the cadmium will bind to the surface oxygen of the material. I looking at fitting sample 1 and 2 using whatever crystallographic info of CdO I can get my hands on. Wonder if the plan make sense. Happy new year, Alan

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Ifeffit "print" command question
by Kelly, Tony D Ctr USAF AETC AFIT/ENP 31 Dec '10

31 Dec '10

To whom it may concern, I have recently downloaded Ifeffit for Mac OS X from your website. I am hoping to be able to use it with EXAFS data as the FEFF6 website led me to your application. I am currently working through the tutorial. However, every time I try to use the print command to make a literal string statement, all I get is 0.0000 back. Example: print " the square root of ", number, " is ", sqrt(number) 0.0 99.0000000 0.0000000 9.94987437 print "Hi mom" 0.000000000 Any thoughts? Thanks, Tony Tony Kelly, M.S. DTRA PhD Student Department of Engineering Physics Air Force Institute of Technology Office: (937)255-3636 ext 7300

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RE : Ifeffit Digest, Vol 94, Issue 5
by KONG Quingyu 21 Dec '10

21 Dec '10

Dear Colleagues, We are measuring EXAFS of Mo foil and Bi2O3 in a dispersive EXAFS beamline, to calibrate the energy we need the standard EXAFS spectra (in energy, not in pixel) of these two samples. We appreciate to anyone who can send us the standard EXAFS spectra of them. Thanks a lot in advance, Sincerely, Qingyu Kong Beamline ODE Société civile Synchrotron SOLEIL L'Orme des Merisiers Saint-Aubin - BP 48 91192 GIF-sur-YVETTE CEDEX Tel: +33 (0)1 69 35 97 84 (office) +33 (0)1 69 35 97 16 (beamline) email: kong(a)synchrotron-soleil.fr -------- Message d'origine-------- De: ifeffit-bounces(a)millenia.cars.aps.anl.gov de la part de ifeffit-request(a)millenia.cars.aps.anl.gov Date: sam. 18/12/2010 19:00 À: ifeffit(a)millenia.cars.aps.anl.gov Objet : Ifeffit Digest, Vol 94, Issue 5 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: Ifeffit Digest, Vol 94, Issue 4 (Matt Newville) ---------------------------------------------------------------------- Message: 1 Date: Sat, 18 Dec 2010 08:33:20 -0600 From: Matt Newville <newville(a)cars.uchicago.edu> To: KONG Quingyu <quingyu.kong(a)synchrotron-soleil.fr>, XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> Subject: Re: [Ifeffit] Ifeffit Digest, Vol 94, Issue 4 Message-ID: <AANLkTimiw7fCxQHUO3CsZ3A4qBs0RVqLamjfG__BHquQ(a)mail.gmail.com> Content-Type: text/plain; charset=GB2312 Hi Qingyu, Sorry the attachment didn't make it to you. It's also at http://cars9.uchicago.edu/gsecars/Data/XAFS_Standards/ --Matt 2010/12/18 KONG Quingyu <quingyu.kong(a)synchrotron-soleil.fr>: > Dear Matt, > > Many thanks for your kind help. > > However, I can not find the file you sent to me. Would you please send them again with an attached file. > > Best regards, > Qingyu > > > Beamline ODE > Soci?t? civile Synchrotron SOLEIL > L'Orme des Merisiers > Saint-Aubin - BP 48 > 91192 GIF-sur-YVETTE CEDEX > Tel: +33 (0)1 69 35 97 84 (office) > +33 (0)1 69 35 97 16 (beamline) > email: kong(a)synchrotron-soleil.fr > > > > > ________________________________ > > From: ifeffit-bounces(a)millenia.cars.aps.anl.gov ?? ifeffit-request(a)millenia.cars.aps.anl.gov > Sent: 18/12/2010 (???) 04:05 > To: ifeffit(a)millenia.cars.aps.anl.gov > Subject: Ifeffit Digest, Vol 94, Issue 4 > > > > 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: RE : Ifeffit Digest, Vol 94, Issue 2 (Matt Newville) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 17 Dec 2010 21:05:28 -0600 > From: Matt Newville <newville(a)cars.uchicago.edu> > To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: Re: [Ifeffit] RE : Ifeffit Digest, Vol 94, Issue 2 > Message-ID: > <AANLkTikuj5+as8e=0+_P-LWH03WhpMW1QrK7PCXpc-VF(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Dear Qingyu, > > I haven't analyzed this data carefully, but attached is an Athena > Project File of some room temperature data on W metal from a > powder-on-tape sample, Si(111) mono, W L3 edge, APS bending magnet > line. I don't have ready details on the absolute calibration, but > the edge energy is reasonably close to the book value. Also included > are EXAFS for WO2 and WO3 (also room temperature, powder-on-tape, > measured under the same conditions). The data for the metal and WO2 > look good out to 17 inverse Angstroms. The WO3 data looks a litle > noisier than the other two, and dies off by 12 inverse Angstroms. > > Hope that helps, > > --Matt > > 2010/12/17 KONG Quingyu <quingyu.kong(a)synchrotron-soleil.fr>: >> Dear Colleague, >> >> Anyone who has an EXAFS spectrum of Tungsten(W), please send me a copy. >> Thanks a lot in advance. >> >> Qingyu Kong >> >> >> Beamline ODE >> Soci?t? civile Synchrotron SOLEIL >> L'Orme des Merisiers >> Saint-Aubin - BP 48 >> 91192 GIF-sur-YVETTE CEDEX >> Tel: +33 (0)1 69 35 97 84 (office) >> ? ? ? +33 (0)1 69 35 97 16 (beamline) >> email: kong(a)synchrotron-soleil.fr >> >> >> >> >> >> >> -------- Message d'origine-------- >> De: ifeffit-bounces(a)millenia.cars.aps.anl.gov de la part de ifeffit-request(a)millenia.cars.aps.anl.gov >> Date: jeu. 16/12/2010 19:00 >> ?: ifeffit(a)millenia.cars.aps.anl.gov >> Objet : Ifeffit Digest, Vol 94, Issue 2 >> >> 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. Soft XAS Postdoc position at The University of Manchester >> ? ? ?(Sven Schroeder) >> >> >> ---------------------------------------------------------------------- >> >> Message: 1 >> Date: Wed, 15 Dec 2010 20:35:41 +0000 >> From: Sven Schroeder <S.Schroeder(a)manchester.ac.uk> >> To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> >> Subject: [Ifeffit] Soft XAS Postdoc position at The University of >> ? ? ? ?Manchester >> Message-ID: >> ? ? ? ?<7457E57E2F521447AC5A411883C1CF71070D15(a)MBXP07.ds.man.ac.uk> >> Content-Type: text/plain; charset="us-ascii" >> >> Dear colleagues >> >> I would be grateful if you could bring this post to the attention of suitable candidates. The post has been funded for 33 months and will be supervised jointly by myself and Rob Lindsay in the School of Materials. >> >> Best regards, >> >> Sven >> >> -- >> >> Research Associate >> School of Chemical Engineering & Analytical Science / School of Materials >> The University of Manchester >> >> High-Pressure Soft X-ray Synchrotron Spectroscopy of Adsorbed Large Organic Molecules for Corrosion Inhibition >> >> Closing date: 11/01/2011 >> Reference: EPS/11323 >> >> http://www.manchester.ac.uk/aboutus/jobs/vacancies/research/vacancy/index.h… >> >> We are seeking to employ a Postdoctoral Research Associate within the School of Chemical Engineering and Analytical Science and the School of Materials on a full-time basis. >> >> A PhD in a relevant scientific discipline and several years of hands-on experience in experimental X-ray spectroscopy (XPS, NEXAFS, other surface techniques) are required. The project focuses on fundamental physicochemical studies of model surface systems to an industrially relevant project involving organic chemists, computational chemists and chemical engineers at the Mexican Petroleum Institute (IMP). As such it requires a candidate with the ability to work both on own initiative as well as a part of teams of varying size. Candidates should have an interest in working across the boundary between fundamental academic science and its practical application. Relevant peer-reviewed publications and experience in writing manuscripts for academic journal publications are essential. The post requires an ability to travel globally and regularly. Experience of using ab initio soft X-ray spectroscopy data analysis packages, including StoBe, FEFF, and CASTEP, or similar computatio! n! > al! >> ?methods would be an advantage. >> >> -- >> Dr Sven L.M. Schroeder (mailto:s.schroeder@manchester.ac.uk) >> >> Reader >> School of Chemical Engineering and Analytical Science (CEAS) >> The University of Manchester, Manchester M13 9PL, United Kingdom >> >> http://www.slmslab.info <http://www.slmslab.info/> >> >> Also at: >> School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom >> >> Tel +44 (161) 306 4502 >> Fax +44 (161) 306 8867 >> >> Office: Room C57 (Jackson's Mill) >> >> DISCLAIMER >> The views expressed within this message are those of the sender, not those of The University of Manchester or one of its units. While all emails and attachments are scanned for viruses before sending, we cannot accept any responsibility for viruses, so please scan all emails and attachments. This email is intended for the addressee only. If you are not the intended recipient, please notify the sender and delete this email immediately. >> >> END OF MESSAGE >> >> >> >> >> >> ------------------------------ >> >> _______________________________________________ >> Ifeffit mailing list >> Ifeffit(a)millenia.cars.aps.anl.gov >> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit >> >> >> End of Ifeffit Digest, Vol 94, Issue 2 >> ************************************** >> >> >> _______________________________________________ >> 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] Ifeffit Digest, Vol 94, Issue 4
by Matt Newville 18 Dec '10

18 Dec '10

Hi Qingyu, Sorry the attachment didn't make it to you. It's also at http://cars9.uchicago.edu/gsecars/Data/XAFS_Standards/ --Matt 2010/12/18 KONG Quingyu <quingyu.kong(a)synchrotron-soleil.fr>: > Dear Matt, > > Many thanks for your kind help. > > However, I can not find the file you sent to me. Would you please send them again with an attached file. > > Best regards, > Qingyu > > > Beamline ODE > Société civile Synchrotron SOLEIL > L'Orme des Merisiers > Saint-Aubin - BP 48 > 91192 GIF-sur-YVETTE CEDEX > Tel: +33 (0)1 69 35 97 84 (office) > +33 (0)1 69 35 97 16 (beamline) > email: kong(a)synchrotron-soleil.fr > > > > > ________________________________ > > From: ifeffit-bounces(a)millenia.cars.aps.anl.gov 代表 ifeffit-request(a)millenia.cars.aps.anl.gov > Sent: 18/12/2010 (星期六) 04:05 > To: ifeffit(a)millenia.cars.aps.anl.gov > Subject: Ifeffit Digest, Vol 94, Issue 4 > > > > 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: RE : Ifeffit Digest, Vol 94, Issue 2 (Matt Newville) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 17 Dec 2010 21:05:28 -0600 > From: Matt Newville <newville(a)cars.uchicago.edu> > To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: Re: [Ifeffit] RE : Ifeffit Digest, Vol 94, Issue 2 > Message-ID: > <AANLkTikuj5+as8e=0+_P-LWH03WhpMW1QrK7PCXpc-VF(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Dear Qingyu, > > I haven't analyzed this data carefully, but attached is an Athena > Project File of some room temperature data on W metal from a > powder-on-tape sample, Si(111) mono, W L3 edge, APS bending magnet > line. I don't have ready details on the absolute calibration, but > the edge energy is reasonably close to the book value. Also included > are EXAFS for WO2 and WO3 (also room temperature, powder-on-tape, > measured under the same conditions). The data for the metal and WO2 > look good out to 17 inverse Angstroms. The WO3 data looks a litle > noisier than the other two, and dies off by 12 inverse Angstroms. > > Hope that helps, > > --Matt > > 2010/12/17 KONG Quingyu <quingyu.kong(a)synchrotron-soleil.fr>: >> Dear Colleague, >> >> Anyone who has an EXAFS spectrum of Tungsten(W), please send me a copy. >> Thanks a lot in advance. >> >> Qingyu Kong >> >> >> Beamline ODE >> Soci?t? civile Synchrotron SOLEIL >> L'Orme des Merisiers >> Saint-Aubin - BP 48 >> 91192 GIF-sur-YVETTE CEDEX >> Tel: +33 (0)1 69 35 97 84 (office) >> ? ? ? +33 (0)1 69 35 97 16 (beamline) >> email: kong(a)synchrotron-soleil.fr >> >> >> >> >> >> >> -------- Message d'origine-------- >> De: ifeffit-bounces(a)millenia.cars.aps.anl.gov de la part de ifeffit-request(a)millenia.cars.aps.anl.gov >> Date: jeu. 16/12/2010 19:00 >> ?: ifeffit(a)millenia.cars.aps.anl.gov >> Objet : Ifeffit Digest, Vol 94, Issue 2 >> >> 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. Soft XAS Postdoc position at The University of Manchester >> ? ? ?(Sven Schroeder) >> >> >> ---------------------------------------------------------------------- >> >> Message: 1 >> Date: Wed, 15 Dec 2010 20:35:41 +0000 >> From: Sven Schroeder <S.Schroeder(a)manchester.ac.uk> >> To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> >> Subject: [Ifeffit] Soft XAS Postdoc position at The University of >> ? ? ? ?Manchester >> Message-ID: >> ? ? ? ?<7457E57E2F521447AC5A411883C1CF71070D15(a)MBXP07.ds.man.ac.uk> >> Content-Type: text/plain; charset="us-ascii" >> >> Dear colleagues >> >> I would be grateful if you could bring this post to the attention of suitable candidates. The post has been funded for 33 months and will be supervised jointly by myself and Rob Lindsay in the School of Materials. >> >> Best regards, >> >> Sven >> >> -- >> >> Research Associate >> School of Chemical Engineering & Analytical Science / School of Materials >> The University of Manchester >> >> High-Pressure Soft X-ray Synchrotron Spectroscopy of Adsorbed Large Organic Molecules for Corrosion Inhibition >> >> Closing date: 11/01/2011 >> Reference: EPS/11323 >> >> http://www.manchester.ac.uk/aboutus/jobs/vacancies/research/vacancy/index.h… >> >> We are seeking to employ a Postdoctoral Research Associate within the School of Chemical Engineering and Analytical Science and the School of Materials on a full-time basis. >> >> A PhD in a relevant scientific discipline and several years of hands-on experience in experimental X-ray spectroscopy (XPS, NEXAFS, other surface techniques) are required. The project focuses on fundamental physicochemical studies of model surface systems to an industrially relevant project involving organic chemists, computational chemists and chemical engineers at the Mexican Petroleum Institute (IMP). As such it requires a candidate with the ability to work both on own initiative as well as a part of teams of varying size. Candidates should have an interest in working across the boundary between fundamental academic science and its practical application. Relevant peer-reviewed publications and experience in writing manuscripts for academic journal publications are essential. The post requires an ability to travel globally and regularly. Experience of using ab initio soft X-ray spectroscopy data analysis packages, including StoBe, FEFF, and CASTEP, or similar computation! > al! >> ?methods would be an advantage. >> >> -- >> Dr Sven L.M. Schroeder (mailto:s.schroeder@manchester.ac.uk) >> >> Reader >> School of Chemical Engineering and Analytical Science (CEAS) >> The University of Manchester, Manchester M13 9PL, United Kingdom >> >> http://www.slmslab.info <http://www.slmslab.info/> >> >> Also at: >> School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom >> >> Tel +44 (161) 306 4502 >> Fax +44 (161) 306 8867 >> >> Office: Room C57 (Jackson's Mill) >> >> DISCLAIMER >> The views expressed within this message are those of the sender, not those of The University of Manchester or one of its units. While all emails and attachments are scanned for viruses before sending, we cannot accept any responsibility for viruses, so please scan all emails and attachments. This email is intended for the addressee only. If you are not the intended recipient, please notify the sender and delete this email immediately. >> >> END OF MESSAGE >> >> >> >> >> >> ------------------------------ >> >> _______________________________________________ >> Ifeffit mailing list >> Ifeffit(a)millenia.cars.aps.anl.gov >> http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit >> >> >> End of Ifeffit Digest, Vol 94, Issue 2 >> ************************************** >> >> >> _______________________________________________ >> 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] RE : Ifeffit Digest, Vol 94, Issue 2
by Matt Newville 18 Dec '10

18 Dec '10

Dear Qingyu, I haven't analyzed this data carefully, but attached is an Athena Project File of some room temperature data on W metal from a powder-on-tape sample, Si(111) mono, W L3 edge, APS bending magnet line. I don't have ready details on the absolute calibration, but the edge energy is reasonably close to the book value. Also included are EXAFS for WO2 and WO3 (also room temperature, powder-on-tape, measured under the same conditions). The data for the metal and WO2 look good out to 17 inverse Angstroms. The WO3 data looks a litle noisier than the other two, and dies off by 12 inverse Angstroms. Hope that helps, --Matt 2010/12/17 KONG Quingyu <quingyu.kong(a)synchrotron-soleil.fr>: > Dear Colleague, > > Anyone who has an EXAFS spectrum of Tungsten(W), please send me a copy. > Thanks a lot in advance. > > Qingyu Kong > > > Beamline ODE > Société civile Synchrotron SOLEIL > L'Orme des Merisiers > Saint-Aubin - BP 48 > 91192 GIF-sur-YVETTE CEDEX > Tel: +33 (0)1 69 35 97 84 (office) > +33 (0)1 69 35 97 16 (beamline) > email: kong(a)synchrotron-soleil.fr > > > > > > > -------- Message d'origine-------- > De: ifeffit-bounces(a)millenia.cars.aps.anl.gov de la part de ifeffit-request(a)millenia.cars.aps.anl.gov > Date: jeu. 16/12/2010 19:00 > À: ifeffit(a)millenia.cars.aps.anl.gov > Objet : Ifeffit Digest, Vol 94, Issue 2 > > 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. Soft XAS Postdoc position at The University of Manchester > (Sven Schroeder) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 15 Dec 2010 20:35:41 +0000 > From: Sven Schroeder <S.Schroeder(a)manchester.ac.uk> > To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> > Subject: [Ifeffit] Soft XAS Postdoc position at The University of > Manchester > Message-ID: > <7457E57E2F521447AC5A411883C1CF71070D15(a)MBXP07.ds.man.ac.uk> > Content-Type: text/plain; charset="us-ascii" > > Dear colleagues > > I would be grateful if you could bring this post to the attention of suitable candidates. The post has been funded for 33 months and will be supervised jointly by myself and Rob Lindsay in the School of Materials. > > Best regards, > > Sven > > -- > > Research Associate > School of Chemical Engineering & Analytical Science / School of Materials > The University of Manchester > > High-Pressure Soft X-ray Synchrotron Spectroscopy of Adsorbed Large Organic Molecules for Corrosion Inhibition > > Closing date: 11/01/2011 > Reference: EPS/11323 > > http://www.manchester.ac.uk/aboutus/jobs/vacancies/research/vacancy/index.h… > > We are seeking to employ a Postdoctoral Research Associate within the School of Chemical Engineering and Analytical Science and the School of Materials on a full-time basis. > > A PhD in a relevant scientific discipline and several years of hands-on experience in experimental X-ray spectroscopy (XPS, NEXAFS, other surface techniques) are required. The project focuses on fundamental physicochemical studies of model surface systems to an industrially relevant project involving organic chemists, computational chemists and chemical engineers at the Mexican Petroleum Institute (IMP). As such it requires a candidate with the ability to work both on own initiative as well as a part of teams of varying size. Candidates should have an interest in working across the boundary between fundamental academic science and its practical application. Relevant peer-reviewed publications and experience in writing manuscripts for academic journal publications are essential. The post requires an ability to travel globally and regularly. Experience of using ab initio soft X-ray spectroscopy data analysis packages, including StoBe, FEFF, and CASTEP, or similar computational! > methods would be an advantage. > > -- > Dr Sven L.M. Schroeder (mailto:s.schroeder@manchester.ac.uk) > > Reader > School of Chemical Engineering and Analytical Science (CEAS) > The University of Manchester, Manchester M13 9PL, United Kingdom > > http://www.slmslab.info > > Also at: > School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom > > Tel +44 (161) 306 4502 > Fax +44 (161) 306 8867 > > Office: Room C57 (Jackson's Mill) > > DISCLAIMER > The views expressed within this message are those of the sender, not those of The University of Manchester or one of its units. While all emails and attachments are scanned for viruses before sending, we cannot accept any responsibility for viruses, so please scan all emails and attachments. This email is intended for the addressee only. If you are not the intended recipient, please notify the sender and delete this email immediately. > > END OF MESSAGE > > > > > > ------------------------------ > > _______________________________________________ > Ifeffit mailing list > Ifeffit(a)millenia.cars.aps.anl.gov > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > > > End of Ifeffit Digest, Vol 94, Issue 2 > ************************************** > > > _______________________________________________ > 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 Digest, Vol 94, Issue 2
by KONG Quingyu 17 Dec '10

17 Dec '10

Dear Colleague, Anyone who has an EXAFS spectrum of Tungsten(W), please send me a copy. Thanks a lot in advance. Qingyu Kong Beamline ODE Société civile Synchrotron SOLEIL L'Orme des Merisiers Saint-Aubin - BP 48 91192 GIF-sur-YVETTE CEDEX Tel: +33 (0)1 69 35 97 84 (office) +33 (0)1 69 35 97 16 (beamline) email: kong(a)synchrotron-soleil.fr -------- Message d'origine-------- De: ifeffit-bounces(a)millenia.cars.aps.anl.gov de la part de ifeffit-request(a)millenia.cars.aps.anl.gov Date: jeu. 16/12/2010 19:00 À: ifeffit(a)millenia.cars.aps.anl.gov Objet : Ifeffit Digest, Vol 94, Issue 2 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. Soft XAS Postdoc position at The University of Manchester (Sven Schroeder) ---------------------------------------------------------------------- Message: 1 Date: Wed, 15 Dec 2010 20:35:41 +0000 From: Sven Schroeder <S.Schroeder(a)manchester.ac.uk> To: XAFS Analysis using Ifeffit <ifeffit(a)millenia.cars.aps.anl.gov> Subject: [Ifeffit] Soft XAS Postdoc position at The University of Manchester Message-ID: <7457E57E2F521447AC5A411883C1CF71070D15(a)MBXP07.ds.man.ac.uk> Content-Type: text/plain; charset="us-ascii" Dear colleagues I would be grateful if you could bring this post to the attention of suitable candidates. The post has been funded for 33 months and will be supervised jointly by myself and Rob Lindsay in the School of Materials. Best regards, Sven -- Research Associate School of Chemical Engineering & Analytical Science / School of Materials The University of Manchester High-Pressure Soft X-ray Synchrotron Spectroscopy of Adsorbed Large Organic Molecules for Corrosion Inhibition Closing date: 11/01/2011 Reference: EPS/11323 http://www.manchester.ac.uk/aboutus/jobs/vacancies/research/vacancy/index.h… We are seeking to employ a Postdoctoral Research Associate within the School of Chemical Engineering and Analytical Science and the School of Materials on a full-time basis. A PhD in a relevant scientific discipline and several years of hands-on experience in experimental X-ray spectroscopy (XPS, NEXAFS, other surface techniques) are required. The project focuses on fundamental physicochemical studies of model surface systems to an industrially relevant project involving organic chemists, computational chemists and chemical engineers at the Mexican Petroleum Institute (IMP). As such it requires a candidate with the ability to work both on own initiative as well as a part of teams of varying size. Candidates should have an interest in working across the boundary between fundamental academic science and its practical application. Relevant peer-reviewed publications and experience in writing manuscripts for academic journal publications are essential. The post requires an ability to travel globally and regularly. Experience of using ab initio soft X-ray spectroscopy data analysis packages, including StoBe, FEFF, and CASTEP, or similar computational! methods would be an advantage. -- Dr Sven L.M. Schroeder (mailto:s.schroeder@manchester.ac.uk) Reader School of Chemical Engineering and Analytical Science (CEAS) The University of Manchester, Manchester M13 9PL, United Kingdom http://www.slmslab.info Also at: School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom Tel +44 (161) 306 4502 Fax +44 (161) 306 8867 Office: Room C57 (Jackson's Mill) DISCLAIMER The views expressed within this message are those of the sender, not those of The University of Manchester or one of its units. While all emails and attachments are scanned for viruses before sending, we cannot accept any responsibility for viruses, so please scan all emails and attachments. This email is intended for the addressee only. If you are not the intended recipient, please notify the sender and delete this email immediately. END OF MESSAGE ------------------------------ _______________________________________________ Ifeffit mailing list Ifeffit(a)millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit End of Ifeffit Digest, Vol 94, Issue 2 **************************************

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Soft XAS Postdoc position at The University of Manchester
by Sven Schroeder 15 Dec '10

15 Dec '10

Dear colleagues I would be grateful if you could bring this post to the attention of suitable candidates. The post has been funded for 33 months and will be supervised jointly by myself and Rob Lindsay in the School of Materials. Best regards, Sven -- Research Associate School of Chemical Engineering & Analytical Science / School of Materials The University of Manchester High-Pressure Soft X-ray Synchrotron Spectroscopy of Adsorbed Large Organic Molecules for Corrosion Inhibition Closing date: 11/01/2011 Reference: EPS/11323 http://www.manchester.ac.uk/aboutus/jobs/vacancies/research/vacancy/index.h… We are seeking to employ a Postdoctoral Research Associate within the School of Chemical Engineering and Analytical Science and the School of Materials on a full-time basis. A PhD in a relevant scientific discipline and several years of hands-on experience in experimental X-ray spectroscopy (XPS, NEXAFS, other surface techniques) are required. The project focuses on fundamental physicochemical studies of model surface systems to an industrially relevant project involving organic chemists, computational chemists and chemical engineers at the Mexican Petroleum Institute (IMP). As such it requires a candidate with the ability to work both on own initiative as well as a part of teams of varying size. Candidates should have an interest in working across the boundary between fundamental academic science and its practical application. Relevant peer-reviewed publications and experience in writing manuscripts for academic journal publications are essential. The post requires an ability to travel globally and regularly. Experience of using ab initio soft X-ray spectroscopy data analysis packages, including StoBe, FEFF, and CASTEP, or similar computational methods would be an advantage. -- Dr Sven L.M. Schroeder (mailto:s.schroeder@manchester.ac.uk) Reader School of Chemical Engineering and Analytical Science (CEAS) The University of Manchester, Manchester M13 9PL, United Kingdom http://www.slmslab.info Also at: School of Chemistry, The University of Manchester, Manchester M13 9PL, United Kingdom Tel +44 (161) 306 4502 Fax +44 (161) 306 8867 Office: Room C57 (Jackson's Mill) DISCLAIMER The views expressed within this message are those of the sender, not those of The University of Manchester or one of its units. While all emails and attachments are scanned for viruses before sending, we cannot accept any responsibility for viruses, so please scan all emails and attachments. This email is intended for the addressee only. If you are not the intended recipient, please notify the sender and delete this email immediately. END OF MESSAGE

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On Macro Lytle File Group
by Alan Du 09 Dec '10

09 Dec '10

Hi IFEFFIT Users, I major in environmental science and my research is studying the adsorption of aqueous cadmium on TiO2 solid. I am new to EXAFS and currently trying to fit my Cd K-edge spectra with some Cd experimental standards. The Farrel Lytle Database have some Cd spectra which seems useful and I would like to extract them from their "raw" state. The macro is given in the FAQ/Data Handling section of IFEFFIT, but I am not sure of how to go about using the macro or any other macro. Ctrl 5 in Athena is all I know. Can anyone advise me on this? # macro lytle file group 4000 read_data ($1, group=$2, label='steps i0 i1 i2') set (dspace = 1.92017, stpdeg = $3) set (r2d = 57.29577951, hc = 12398.61) set $2.energy = hc / (2 * dspace) / sin($2.steps / (r2d * stpdeg)) set $2.xmut = -log($2.i1/$2.i0) set $2.xmuf = ($2.i2/$2.i0) pre_edge $2.energy, $2.xmut end macro Cheers, Alan -- Alan Jianhong DU Research Student Nanyang Technological University, Singapore School of Civil & Environmental Engineering Blk N1, N1-B4b-04, 50 Nanyang Avenue, Singapore 639798 Mobile: +65 9621 6991 Fax: +65 6861 5254

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iXAFS
by George Sterbinsky 29 Nov '10

29 Nov '10

Hi, I am wondering what is the best way to uninstall iXAFS version 2.1.1 for Leopard before installing the new version. Is it sufficient to just drag iXAFS.app to the trash or is there a better way to make sure everything gets removed? Thank you, George

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Re: [Ifeffit] Distortion of transmission spectra due to particle size
by Scott Calvin 26 Nov '10

26 Nov '10

Let me try again. First of all, perhaps you missed that after my first post, I acknowledged that my statement in the first post was mistaken? In fact, I later said: > So there's nothing wrong with the arguments in Lu and Stern, > Scarrow, etc.--it's the notion I had that we use multiple layers of > tape to improve uniformity that's mistaken. The Lu and Stern paper, which I now agree with, comes up with an equation I have attached as a png file. That equation is derived for spheres of diameter D in a monolayer. It does, incidentally, include a typo; the part inside the ln should start with mu_2^2/mu_1^2. But that's just typographical, and doesn't affect their subsequent argument. Lu and Stern then make the following claim: > Finally, the attenuation in N layers is given by (I/I0)^N, where I > is the transmitted intensity through one layer. Chi_eff for N layers > is then the same as for a single layer since N will cancel in the > final result. That's the statement I initially thought was incorrect, and thought was equivalent to a non-random stacking of layers. Since I'm now convinced that the statement is correct, I don't want to get bogged down in a discussion of why I still find it a bit puzzling. Other than my first post, no one else in this thread has yet challenged the Lu and Stern statement, and some, such as Matthew Marcus, have supported it. The statement can be rephrased to say that, for a given particle diameter D, the ratio of chi_eff to chi_real is independent of the number of layers; that is, the distortion due to nonuniformity is not reduced by adding additional identical layers. I found this conclusion so startling that at first I rejected it. Several others in this thread indicated that they too tended to think that additional identical layers would reduce distortions in the spectrum due to nonuniformity. I then tested this principle that emerges from the Lu and Stern paper in two other situations, and found that it holds in those as well. Here are the details: The first case I'll examine is a Gaussian distribution of standard deviation sigma and average width x_o, with a distribution narrow enough so that we can ignore the negative-thickness tail. Grant Bunker has investigated this case, for example on page 88 of his new textbook. The derivation is straightforward, and he finds that (mu x)_eff = mu x_o - (mu sigma)^2/2 Your simulation beautifully demonstrates that when I use N layers of this type, we can expect that the new mean thickness x_new = N x_o, and sigma_new = sqrt(N) sigma. This gives: (mu x)_new_eff = mu N x_o - [mu sqrt(N) sigma]^2/2 = N [mu x_o - (mu sigma)^2/2] = N (mu x)_eff Thus the new spectrum is exactly the same shape as the old spectrum-- just scaled up by a factor of N. Therefore, after normalization, the spectrum of the multi-layer sample will be exactly the same as for the single layer. (Note that this analysis does not include the effect of signal to noise, harmonics, etc.). Thus the distortion due to nonuniformity is independent of the number of identical layers used. My next thought was to see if this was a peculiarity of normally distributed samples and monolayers of spheres. After all, extremely nonuniform samples will tend to approach a Gaussian thickness distribution as more layers are randomly stacked up--perhaps they asymptotically approach the distortion present in the Gaussian case? So I investigated pinholes. This time I did the calculation all the way from scratch, just to make sure I understood all the assumptions. Take a sample that has a fraction p of pinholes, with the remaining 1- p of the sample being of uniform thickness x. In that case, I = p I_o + (1-p) I_o exp(-mu x) mu_eff = ln (I/I_o) = ln [p + (1-p) exp(-mu x)] Now take two layers of that type, with the pinholes randomly distributed. A fraction p^2 will still be pinhole, a fraction 2p(1-p) will have thickness x, and a fraction (1-p)^2 will have thickness x^2. So now I/I_o = p^2 + 2p(1-p) exp(-mu x) + (1-p)^2 exp(-2 mu x) mu_eff = ln[p^2 + 2p(1-p) exp(-mu x) + (1-p)^2 exp(-2 mu x)] = ln[p+(1- p)exp(-mu x)]^2 = 2ln[p + (1-p) exp(-mu x)] And that is exactly twice the mu_eff of the single layer--i.e., after normalization it will be identical. Any distortions caused by pinholes will be identical, despite the fraction of sample having pinholes all the way through dropping from p to p^2. Some in our community already realized that, but I didn't. In fact, I'd go so far as to say I was shocked by the result. Judging by some of the advice that is routinely given about sample preparation, I suspect that this may come as a surprise to many others as well. Hopefully that establishes what my understanding currently is. Beyond that, we seem to be miscommunicating on some questions of terminology: On Nov 24, 2010, at 12:04 PM, Matt Newville wrote: > Scott, > > You said: >> the distortion from nonuniformity is as bad for four strips >> stacked as for the single strip. > > As I showed earlier, a four layer sample is more uniform than a one > layer sample, whether the total thickness is preserved or the > thickness per layer is preserved. > >> For 1% pinholes: >> # N_layers | % Pinholes | Ave Thickness | Thickness Std Dev | >> # 1 | 1.0 | 0.990 | 0.099 | >> # 5 | 1.0 | 4.950 | 0.225 | >> # 25 | 1.0 | 24.750 | 0.500 | > > Yes, the sample with 25 layers has a more uniform thickness. > >> As before, the standard deviation increases as square root of N. >> Using a >> cumulant expansion (admittedly slightly funky for such a broad >> distribution) necessarily yields the same result as the Gaussian >> distribution: the shape of the measured spectrum is independent of >> the >> number of layers used! And as it turns out, an exact calculation >> (i.e. not >> using a cumulant expansion) also yields the same result of >> independence. > > OK... The shape is the same, but the relative widths change. > > 24.75 +/- 0.50 is a more uniform distribution than 0.99 +/- .099. > Perhaps this is what is confusing you? The thicker sample is more uniform (in the sense of fractional uniformity), but the distortion in the normalized mu(E) due to the nonuniformity is identical. That is exactly what is surprising, and what I initially did not believe. Now I am firmly convinced that it is true. > >> So Lu and Stern got it right. But the idea that we can mitigate >> pinholes by >> adding more layers is wrong. > > Adding more layers does make a sample of more uniform thickness. > Perhaps "mitigate pinholes" means something different to you? By "mitigate pinholes" I mean that we can obtain a normalized energy spectrum that is closer to the mu(E) we are trying to measure. But we can't do that by adding more identically distributed layers if the thick and thin spots are randomly stacked--we end up with exactly the same normalized mu(E). (As usual, this analysis neglects signal to noise, harmonics, and the like.) I used a lot of words there to try to be precise. But basically, stacking two layers of tape with the hope that pinholes will tend to be cancelled out will not work. > > In your original message (in which you set out to "track down" a piece > of "incorrect lore") you said that Lu and Stern assumed that layers > were stacked "so that thick spots are always over thick and thin spots > over thin". They did not assume that. Given that initial > misunderstanding, and the fact that you haven't shown any calculations > or simulations, it's a bit hard for me to fathom what you think Lu and > Stern "got right" or wrong. They got everything right. I was trying to save a different piece of lore that I think is even more widely disseminated--that stacking thin layers of tape reduces the amount of distortion due to nonuniformity as compared to one thin layer of tape. I thought I had shown calculations (the Gaussian case), and Jeremy has shown simulations which confirm the result for the pinhole case. > The main point of their work is that it is better to use more > layers to get to a given thickness. You seem to have some objection > to this, but I cannot figure out what you're trying to say. I agree that your statement is a true one which is also consistent with their paper, but would respectfully differ as to what the main point of the paper is. The abstract reads: > Powdered samples samples are commonly used to measure the extended X- > ray absorption fine structure (EXAFS) and near-edge structure. It is > shown that sizes of particles typically employed produce significant > reduction in the EXAFS amplitude for concentrated samples. The > distortion is calculated and found to be in good agreement with > measurements on FeSi2 samples. To obtain accurate EXAFS amplitudes > on powdered samples it is necessary to use particles significantly > smaller than 400 mesh when the atom of interest is concentrated. The use of increasing number of layers as the particles are sieved more finely is done to provide a controlled experiment in which differences in signal to noise and thickness effects are not a factor. Suggesting that it is better to use more layers to get a given thickness is an indirect way of getting at the real issue, which is particle size. For a given particle size, multiple layers provide no help whatsoever with nonuniformity-related distortions, but merely allow for the desired signal to noise. Lu and Stern provide the correct emphasis in their paper. It is only some of the subsequent XAFS practitioners, including myself until about 24 hours ago, who placed the stress on the multiple layers per se as addressing the uniformity issue. --Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory

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Re: [Ifeffit] Distortion of transmission spectra due to particle size
by Scott Calvin 24 Nov '10

24 Nov '10

Matt, Your second simulation confirms what I said: > The standard deviation in thickness from point to point in a stack > of N tapes generally increases as the square root of N (typical > statistical behavior). Now follow that through, using, for example, Grant Bunker's formula for the distortion caused by a Gaussian distribution: (mu x)eff = mu x_o - (mu sigma)^2/2 where sigma is the standard deviation of the thickness. So if sigma goes as square root of N, and x_o goes as N, the fractional attenuation of the measured absorption stays constant, and the shape of the measured spectrum stays constant. There is thus no reduction in the distortion of the spectrum by measuring additional layers. Your pinholes simulation, on the other hand, is not the scenario I was describing. I agree it is better to have more thin layers rather than fewer thick layers. My question was whether it is better to have many thin layers compared to fewer thin layers. For the "brush sample on tape" method of sample preparation, this is more like the question we face when we prepare a sample. Our choice is not to spread a given amount of sample over more tapes, because we're already spreading as thin as we can. Our choice is whether to use more tapes of the same thickness. We don't have to rerun your simulation to see the effect of using tapes of the same thickness. All that happens is that the average thickness and the standard deviation gets multiplied by the number of layers. So now the results are: For 10% pinholes, the results are: # N_layers | % Pinholes | Ave Thickness | Thickness Std Dev | # 1 | 10.0 | 0.900 | 0.300 | # 5 | 10.0 | 4.500 | 0.675 | # 25 | 10.0 | 22.500 | 1.500 | For 5% pinholes: # N_layers | % Pinholes | Ave Thickness | Thickness Std Dev | # 1 | 5.0 | 0.950 | 0.218 | # 5 | 5.0 | 4.750 | 0.485 | # 25 | 5.0 | 23.750 | 1.100 | For 1% pinholes: # N_layers | % Pinholes | Ave Thickness | Thickness Std Dev | # 1 | 1.0 | 0.990 | 0.099 | # 5 | 1.0 | 4.950 | 0.225 | # 25 | 1.0 | 24.750 | 0.500 | As before, the standard deviation increases as square root of N. Using a cumulant expansion (admittedly slightly funky for such a broad distribution) necessarily yields the same result as the Gaussian distribution: the shape of the measured spectrum is independent of the number of layers used! And as it turns out, an exact calculation (i.e. not using a cumulant expansion) also yields the same result of independence. So Lu and Stern got it right. But the idea that we can mitigate pinholes by adding more layers is wrong. --Scott Calvin Faculty at Sarah Lawrence College Currently on sabbatical at Stanford Synchrotron Radiation Laboratory On Nov 24, 2010, at 6:05 AM, Matt Newville wrote: > Scott, > >> OK, I've got it straight now. The answer is yes, the distortion from >> nonuniformity is as bad for four strips stacked as for the single >> strip. > > I don't think that's correct. > >> This is surprising to me, but the mathematics is fairly clear. >> Stacking >> multiple layers of tape rather than using one thin layer improves >> the signal >> to noise ratio, but does nothing for uniformity. So there's nothing >> wrong >> with the arguments in Lu and Stern, Scarrow, etc.--it's the notion >> I had >> that we use multiple layers of tape to improve uniformity that's >> mistaken. > > Stacking multiple layers does improve sample uniformity. > > Below is a simple simulation of a sample of unity thickness with > randomly placed pinholes. First this makes a sample that is 1 layer > of N cells, with each cell either having thickness of 1 or 0. Then it > makes a sample of the same size and total thickness, but made of 5 > independent layers, with each layer having the same fraction of > randomly placed pinholes, so that total thickness for each cell could > be 1, 0.8, 0.6, 0.4, 0.2, or 0. Then it makes a sample with 25 > layers. > > The simulation below is in python. I do hope the code is > straightforward enough so that anyone interested can follow. The way > in which pinholes are randomly selected by the code may not be > obvious, so I'll say hear that the "numpy.random.shuffle" function is > like shuffling a deck of cards, and works on its array argument > in-place. > > For 10% pinholes, the results are: > # N_layers | % Pinholes | Ave Thickness | Thickness Std Dev | > # 1 | 10.0 | 0.900 | 0.300 | > # 5 | 10.0 | 0.900 | 0.135 | > # 25 | 10.0 | 0.900 | 0.060 | > > For 5% pinholes: > # N_layers | % Pinholes | Ave Thickness | Thickness Std Dev | > # 1 | 5.0 | 0.950 | 0.218 | > # 5 | 5.0 | 0.950 | 0.097 | > # 25 | 5.0 | 0.950 | 0.044 | > > For 1% pinholes: > # N_layers | % Pinholes | Ave Thickness | Thickness Std Dev | > # 1 | 1.0 | 0.990 | 0.099 | > # 5 | 1.0 | 0.990 | 0.045 | > # 25 | 1.0 | 0.990 | 0.020 | > > Multiple layers of smaller particles gives a more uniform thickness > than fewer layers of larger particles. The standard deviation of the > thickness goes as 1/sqrt(N_layers). In addition, one can see that 5 > layers of 5% pinholes is about as uniform 1 layer with 1% pinholes. > Does any of this seem surprising or incorrect to you? > > Now let's try your case of 1 layer of thickness 0.4 with 4 layers of > thickness 0.4, with 1% pinholes. In the code below, the simulation > would look like > # one layer of thickness=0.4 > sample = 0.4 * make_layer(ncells, ph_frac) > print format % (1, 100*ph_frac, sample.mean(), sample.std()) > > # four layers of thickness=0.4 > layer1 = 0.4 * make_layer(ncells, ph_frac) > layer2 = 0.4 * make_layer(ncells, ph_frac) > layer3 = 0.4 * make_layer(ncells, ph_frac) > layer4 = 0.4 * make_layer(ncells, ph_frac) > sample = layer1 + layer2 + layer3 + layer4 > print format % (4, 100*ph_frac, sample.mean(), sample.std()) > > and the results are: > # N_layers | % Pinholes | Ave Thickness | Thickness Std Dev | > # 1 | 1.0 | 0.396 | 0.040 | > # 4 | 1.0 | 1.584 | 0.080 | > > The sample with 4 layers had its average thickness increase by a > factor of 4, while the standard deviation of that thickness only > doubled. The sample is twice as uniform. > > OK, that's a simple model and of thickness only. Lu and Stern did a > more complete analysis and made actual measurements of the effect of > thickness on XAFS amplitudes. They *showed* that many thin layers is > better than fewer thick layers. > > Perhaps I am not understanding the points you're trying to make, but I > think I am not the only one confused by what you are saying. > > --Matt >

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