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

Re: [Ifeffit] How to use Artemis with feff85L
by Bruce Ravel 12 Jan '18

12 Jan '18

Jose, I am unclear what you are sad about. The version of Feff has little to do with the quality of the analysis. See our recent paper: https://doi.org/10.1107/S1600577517011651 It is true that feff8l would simplify and streamline the code, making it easier to write and maintain. That's a bit incentive /for/ /me/ to do that work. But I think you are overstating the impact on the analysis you and others do with Artemis. B On 01/12/2018 07:15 AM, José Carlos Conesa wrote: > OK Bruce, I understand. (Sigh) > > Good luck in your actual job. > > JC > > > El 12/01/2018 a las 12:35, Bruce Ravel escribió: >> >> Yes. But I am pretty busy these with my new beamline. >> >> "Beamline scientist" is my actual job. "Software guy" is a side >> project. So the software work gets done when it gets done. >> >> B >> >> >> >> On 01/12/2018 05:25 AM, José Carlos Conesa wrote: >>> Dear Bruce, >>> >>> Do you foresee that (in a not far future) Artemis may be adapted so >>> that it can use the results of feff8.5L? >>> >>> All the best, >>> >>> >>> El 12/09/2017 a las 19:11, Bruce Ravel escribió: >>>> >>>> Feff8L is not properly integrated into Artemis yet. Sorry. I have >>>> a new beamline these days. It's hard to find time to work on the >>>> software. >>>> >>>> This is on my to do list, but it's going to take a while. >>>> >>>> B >>>> >>>> >>>> On 09/12/2017 12:54 PM, José Carlos Conesa wrote: >>>>> Hi, >>>>> >>>>> I should like to use feff85L within Artemis (from Demeter 0.9.25), >>>>> just to check in my system whether selfconsistency has a role in >>>>> unifying E0 values (with feff 6, allowing different E0 for each >>>>> scatterer leads to E0 differences >10 eV, which seems too much to >>>>> me). I find that after loading the EXAFS data (from Athena) and a >>>>> model (a .cif file containing Cu, Ce and O atoms), if I click Run >>>>> Atoms and then Run Feff with feff6 as executable I get the usual >>>>> set of paths that allow me doing a fit of the data, but if I try to >>>>> use the feff85L.exe that comes with the Demeter software (by >>>>> changing the feff executable in the File/Edit preferences menu), >>>>> after clicking the Run Feff button (without including the SCF card) >>>>> a bit of computation happens and after finishing it the path list >>>>> is empty. >>>>> >>>>> ¿Any idea of the possible reason why I get no path list? >>>>> >>>>> Thanks in advance >>>>> >>>> >>>> >>> >> >> > -- Bruce Ravel ------------------------------------ bravel(a)bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 743, Room 114 Upton NY, 11973 Homepage: http://bruceravel.github.io/home/ Beamline: https://www.bnl.gov/ps/beamlines/beamline.php?r=6-BM Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/

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Re: [Ifeffit] How to use Artemis with feff85L
by Bruce Ravel 12 Jan '18

12 Jan '18

Yes. But I am pretty busy these with my new beamline. "Beamline scientist" is my actual job. "Software guy" is a side project. So the software work gets done when it gets done. B On 01/12/2018 05:25 AM, José Carlos Conesa wrote: > Dear Bruce, > > Do you foresee that (in a not far future) Artemis may be adapted so that > it can use the results of feff8.5L? > > All the best, > > > El 12/09/2017 a las 19:11, Bruce Ravel escribió: >> >> Feff8L is not properly integrated into Artemis yet. Sorry. I have a >> new beamline these days. It's hard to find time to work on the software. >> >> This is on my to do list, but it's going to take a while. >> >> B >> >> >> On 09/12/2017 12:54 PM, José Carlos Conesa wrote: >>> Hi, >>> >>> I should like to use feff85L within Artemis (from Demeter 0.9.25), >>> just to check in my system whether selfconsistency has a role in >>> unifying E0 values (with feff 6, allowing different E0 for each >>> scatterer leads to E0 differences >10 eV, which seems too much to >>> me). I find that after loading the EXAFS data (from Athena) and a >>> model (a .cif file containing Cu, Ce and O atoms), if I click Run >>> Atoms and then Run Feff with feff6 as executable I get the usual set >>> of paths that allow me doing a fit of the data, but if I try to use >>> the feff85L.exe that comes with the Demeter software (by changing the >>> feff executable in the File/Edit preferences menu), after clicking >>> the Run Feff button (without including the SCF card) a bit of >>> computation happens and after finishing it the path list is empty. >>> >>> ¿Any idea of the possible reason why I get no path list? >>> >>> Thanks in advance >>> >> >> > -- Bruce Ravel ------------------------------------ bravel(a)bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 743, Room 114 Upton NY, 11973 Homepage: http://bruceravel.github.io/home/ Beamline: https://www.bnl.gov/ps/beamlines/beamline.php?r=6-BM Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/

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Some questions regarding running Larch code in Python
by Hanyu Zhang 09 Jan '18

09 Jan '18

Hello everyone, I'm trying to find radial distribution functions for materials with known concentrations of individual atoms by running Larch code through Python, but am having some difficulties with creating feffpaths: 1. I'm not quite understanding the feff.inp files stuff. Calling FeffRunner().run() with a input file that works with Atoms always throws the "rdinp not found exception". From what I'm understanding, feffrunner().run() calls the different modules to create a feffpath() group, but where are the rdinp, pot, xsph, etc codes/files? 2. Somewhat on the same line of thought, can someone give me an example of a valid feffNNNN.dat file to generate a feffpath() group? I went through feffdat.py and the parsing code in lines 88-102 (under __read()) looks like it only accepts very specific input formats. 3. What does "ipot" stand for in the "geom" variable? I understand that if I did pass in a valid file, I'd probably not have to know this, but I was just curious... Also, this might be a overly-general question, but is this the best way to approach the problem? The basic idea now is to get chi(k) values for a bunch of different paths/RDFs, and figure out which ones match experimental values the best. This is also the main reason I want to get past the Demeter GUI and Larch-specific interface: eventually I might throw the code on a supercomputer of some sort and have it crunch the numbers. The details still have to be worked out on my end, but I was wondering if there was a faster or better way to go about finding the RDF for compound materials with known concentrations of individual atoms. I've attached some of my Python code (with more specific versions of questions 1 and 2 inserted as comments) and the feff.inp file I've been testing with. (Simple file from http://cars9.uchicago.edu/~ newville/adb/search.html) I'm currently an undergrad exploring the field of XAFS, so sorry in advance if there is something obvious that I'm missing... Also, let me know if any clarifications are needed. Thank you for your time and sorry about the email being so long, Alice ---------- Hanyu (Alice) Zhang CWRU Class of 2018 | Engineering Physics major BS/MS program | Materials science *Minors:* Mathematics | Materials science *Honors societies:* National Society of Collegiate Scholars | Tau Beta Pi | Pi Mu Epsilon *Active Clubs:* Case Origami Circle | Case Rocket Team | CWRUbotix | Case Physics and Astronomy club | Math club

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data table for larch data group
by Bruce Ravel 22 Dec '17

22 Dec '17

Matt, If I read an ascii file with read_ascii() like so: a = read_ascii(file) The "a" group has a data attribute which contains the entire data table as a 2D array. It also has 1D arrays for each column from the data table. Those 1D arrays have attribute names taken from the column labels. If I do something to change the data table, is there a function that I can call that repopulates the 1D arrays with the columns of the altered data table? For example: a = read_ascii(file) a.data is, say, array<shape=(5,500)> a.data = a.data[:, (0 .. 10)] now a.data is, say, array<shape=(5,11)> a.repopulate_arrays() # <---- the thing i am looking for.... Now a.energy, a.i0, etc should be array<shape=(11,)> Hope that's clear. B -- Bruce Ravel ------------------------------------ bravel(a)bnl.gov National Institute of Standards and Technology Synchrotron Science Group at NSLS-II Building 743, Room 114 Upton NY, 11973 Homepage: http://bruceravel.github.io/home/ Beamline: https://www.bnl.gov/ps/beamlines/beamline.php?r=6-BM Software: https://github.com/bruceravel Demeter: http://bruceravel.github.io/demeter/

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looking for β-Mo2C standard
by woschangqiang＠126.com 13 Dec '17

13 Dec '17

Hello, dear everyone. I am analysing some data about Mo K edge, but lack of standards. I searched many websites and mailing list, and only found the data from Carlo Segre. I am still need the data of β-Mo2C. Can anyone help sent me a data copy, if you have β-Mo2C. Thank you very much. Best regards, Qiang CHANG UCAS

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Units for density in Athena's Booth self-absorption correction?
by John Christopher Lin 11 Dec '17

11 Dec '17

Dear XAFS community, I am trying to use the Booth algorithm to correct for self-absorption in Athena, and one of the input fields is for the density of the material. What units should be used for the density in that field? (I could not find the answer in Section 9.9 of the Athena documentation on self-absorption approximations.) Many thanks, John

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how to import this kind of XAFS data
by woschangqiang＠126.com 11 Dec '17

11 Dec '17

Dear Bruce Ravel, Matt Newville and Carlo Segre, I am sorry to reply late. Thanks very much for your time and detailed explanations. Qiang CHANG Unversity of Chinese Academy of Sciences

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Re: [Ifeffit] Ifeffit Digest, Vol 178, Issue 9
by Christopher Thomas Chantler 10 Dec '17

10 Dec '17

Dear all The two best tests of any self-absorption correction are 1. that the resulting curve looks like an absorption curve, and the slope is consistent with one above the edge and 2. the pixels in a two-dimensional detector are consistent with such a pixel-dependent correction without excessive fitting parameters. That is, the pixel geometry is corrected for. It is not trivial to do this with a single channel, pixel or spectrum. Chris -------------------------------------------------------------------------------------- Christopher Chantler, Professor, FAIP, Fellow American Physical Society Editor-in-Chief, Radiation Physics and Chemistry Chair, International IUCr Commission on XAFS CIT, CCN President, International Radiation Physics Society School of Physics, University of Melbourne Parkville Victoria 3010 Australia +61-3-83445437 FAX +61-3-93474783 chantler(a)unimelb.edu.au<https://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdA…> chantler(a)me.com<https://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdA…> http://optics.ph.unimelb.edu.au/~chantler/xrayopt/xrayopt.html<https://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdA…> http://optics.ph.unimelb.edu.au/~chantler/home.html<https://owa.unimelb.edu.au/owa/redir.aspx?C=c7BoS0kVVkC1_S95-9x9l5cBu6YTjdA…> ________________________________ From: Ifeffit <ifeffit-bounces(a)millenia.cars.aps.anl.gov> on behalf of ifeffit-request(a)millenia.cars.aps.anl.gov <ifeffit-request(a)millenia.cars.aps.anl.gov> Sent: Monday, 11 December 2017 5:00:01 AM To: ifeffit(a)millenia.cars.aps.anl.gov Subject: Ifeffit Digest, Vol 178, Issue 9 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. Units for density in Athena's Booth self-absorption correction? (John Christopher Lin) 2. Re: Units for density in Athena's Booth self-absorption correction? (Matt Newville) ---------------------------------------------------------------------- Message: 1 Date: Sun, 10 Dec 2017 02:30:05 +0000 From: John Christopher Lin <jlin9(a)stanford.edu> To: "ifeffit(a)millenia.cars.aps.anl.gov" <ifeffit(a)millenia.cars.aps.anl.gov> Subject: [Ifeffit] Units for density in Athena's Booth self-absorption correction? Message-ID: <MWHPR02MB3358E7D14D4E058A9F44C79F8F360(a)MWHPR02MB3358.namprd02.prod.outlook.com> Content-Type: text/plain; charset="iso-8859-1" Dear XAFS community, I am trying to use the Booth algorithm to correct for self-absorption in Athena, and one of the input fields is for the density of the material. What units should be used for the density in that field? (I could not find the answer in Section 9.9 of the Athena documentation on self-absorption approximations.) Many thanks, John

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how to import this kind of XAFS data
by woschangqiang＠126.com 08 Dec '17

08 Dec '17

Hello, dear everyone. I downloaded a XAFS data about mettalic Ru from the website of ixs.iit.edu. There are 4 groups of information in the data, and each ranges between ~67800 with ~63000 in energy. So how to import the data to Athena, and how this kind of data was produced? Does anyone come across this situation? Thanks for your time and help in advance. Q. CHANG Unversity of Chinese of Academy of Sciences

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Hello
by Neama Imam 08 Dec '17

08 Dec '17

Dear Sir I am new user of Demeter, i would like to find he exact steps of Athena and Artemis. Best Regards Neama Imam : Post Doc. Position - XAFS beamline - Elettra-Sincrotrone Trieste S.C.p.A. Strada Statale 14, Km 163.5 Basovizza (Trieste), 34149 Trieste-Italia ( neama.imam(a)elettra.eu) and Lecturer : Atomic Energy Authority Nuclear Research Center Exp. Nuclear Phys. Dept. Solid State and Nanotechnology Lab. Cairo, Abou-Zabaal, Inshas , Egypt P.O. : 13759 Fax: 00-202-44520612 imam.eaea(a)gmail.com, nama_emam2018(a)yahoo.com

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Re: [Ifeffit] Demeter 0.9.26 launch faillure
by Kirill Lomachenko 06 Dec '17

06 Dec '17

Dear Kathy and Robert, great, it works! Thanks a lot Kirill

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Demeter 0.9.26 launch faillure
by Kirill Lomachenko 06 Dec '17

06 Dec '17

Dear Bruce, I have trouble running the Demeter 0.9.26_pre2 (64bit). When I start Artemis after installation of Demeter, it closes after showing nothing but the usual temple picture. Logfile is attached. The problem is analogous on both Win7 SP1 and Win8.1 and repeats also for Athena and Hephaestus. Could you please tell whether there is something I can do to fix it? Versions 0.9.25 and 0.9.24 start without problems. I know that 0.9.26 is a preview version, but I was installing it only to get the possibility to actually use the user-supplied value of epsilon_k for fitting multiple dataset. If it is difficult to make the version 0.9.26 available soon, maybe in 0.9.25 there is a possibility to set R-factor as a figure of merit for fitting rather than chi^2? That might also help. Thank you All the best, Kirill Lomachenko -- Dr. Kirill A. Lomachenko Scientist at BM23/ID24 beamlines European Synchrotron Radiation Facility (ESRF) 71 avenue des Martyrs CS 40220 38043 Grenoble Cedex 9, France Tel: +33 438 88 19 14 www.esrf.eu

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Vanadium pre-edge peak fitting
by Will Bennett 06 Dec '17

06 Dec '17

Hi everyone, I've recently collected some V K-edge XANES spectra and am in the process of analysing the data. The pre-edge region has been shown to be quite useful for exploring the oxidation state and coordination geometry of vanadium in various samples. This approach requires the pre-edge peak area and centroid of unknowns to be compared with those of a suite of standards, with these parameters typically determined by fitting a peak (or peaks) to the pre-edge feature. The attached paper by Chaurand et al shows an example of how this is often done, but it raised a question in my mind that I wanted to clarify before proceeding to analyse my data in this way... Is it necessary to justify a particular selection of peak fitting parameters based on physical attributes? For example, Chaurand et al fits multiple pseudo-voigt peaks to the V pre-edge feature, with the Lorentzian contribution to this pseudo-voigt function constrained to be the same as the core-hole lifetime width at the V K-edge (i.e. 0.8 eV). The Gaussian contribution is allowed to vary, but the Lorentzian to Gaussian intensity ratio is set at 1:1. After justifying these parameters, the authors go on to say that *"It should be noted that width and height of the modeled pseudo-Voigt functions have little physical significance, being a convolution of two functions with significantly different width."* If this is the case, does it really matter what specific peak fitting parameters are used? If the goal is to simply obtain an accurate peak area and centroid of the pre-edge feature, wouldn't an empirical peak fitting approach provide comparable data? I'm not against fitting a series of pseudo-voigt functions constrained in a similar way, to my data, but I'd like to have a good justification for doing so. I'm quite new to the world of peak fitting in the context of XAS data analysis, so I'm looking forward to hearing the views of the mailing list. Thanks in advance. Will

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Tenure track position in condensed matter physics
by Robert Meulenberg 01 Dec '17

01 Dec '17

Hello all, I hope I'm not overstepping any bounds here, but I know that this mailing list is populated with both experimentalists and theorists, so I figured the email could be of interest. The University of Maine is looking to hire a theoretical/computational condensed matter physicist for a tenure track Assistant Professor position. I have attached the ad and the link to the position can be found here: https://umaine.hiretouch.com/job-details?jobID=44990&job=assistant-professo… Please feel free to circulate as you see fit. Regards, Rob Meulenberg Robert W. Meulenberg Associate Professor of Physics Laboratory for Surface Science and Technology Department of Physics and Astronomy University of Maine Orono, ME 04469 phone: 207-581-2245 email: robert.meulenberg(a)maine.edu

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Introduction to Synchrotron Radiation Course Online for Spring 2018
by Carlo Segre 29 Nov '17

29 Nov '17

Hello All: Illinois Tech's PHYS 570 (Introduction to Synchrotron Radiation) Course will be offered in the Spring semester of 2018 starting January 8, 2018. This is a graduate level course suitable for students in all science and engineering disciplines interested in learning more about synchrotron radiation production, instrumentation and experimental techniques. This is a for credit course which has both a live and online section. Lectures will be presented live on Tuesdays and Thursdays and will be posted for the online section within 12 hours through Illinois Institute of Technology's Blackboard system. A short description of the course is below. If you have an interest in this course, please contact me (Carlo Segre <segre(a)iit.edu>) for more details. PHYS 570 - Introduction to Synchrotron Radiation Term: Spring 2018, January 8, 2018 – May 5, 2018 Time: Tuesday & Thursday 13:50-15:05 Location: Live & Internet Instructor: Carlo U. Segre Description: This is a graduate course which introduces students to the production, manipulation and use of synchrotron radiation in research. The course will include visits to, and possibly hands-on experience with, beamlines at the Advanced Photon Source (APS) at Argonne National Laboratory but is not specific to the APS. Students will be expected to give presentations and write a General User Proposal to the APS as their final projects. Graduate students in any science or engineering program are welcome to register as are undergraduates with senior standing and permission of instructor. It is particularly recommended for students wishing to make use of synchrotron radiation in their research. The class meets Tuesdays and Thursdays 17:00-18:15 and the lectures are available online as an Internet section for students not on the IIT campus or outside the United States. Textbook: Elements of Modern X-Ray Physics, 2nd ed., Jen Als-Nielsen and Des McMorrow, (John Wiley & Sons, Ltd. 2011). Topics Covered: • X-rays and their interaction with matter • Sources of x-rays • Refraction and reflection from interfaces • Kinematical Diffraction • Diffraction by perfect crystals • Photoelectric absorption • Resonant scattering • Small angle scattering • Other topics as appropriate Course Organization: The grade will be based equally on homework assignments, student presentations and a draft General User Proposal to the Advanced Photon Source. There will be at least one field trip to the Advanced Photon Source for experiment demonstrations. -- Carlo U. Segre -- Duchossois Leadership Professor of Physics Interim Chair, Department of Chemistry Director, Center for Synchrotron Radiation Research and Instrumentation Illinois Institute of Technology Voice: 312.567.3498 Fax: 312.567.3494 segre(a)iit.edu http://phys.iit.edu/~segre segre(a)debian.org

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Athena: Data cannot be imported by using plugin PFBL12C
by 平岡　裕治 16 Nov '17

16 Nov '17

Dear all, I tried to import a data of multi-element detector at SPring-8 by using plugin PFBL12C to Athena, but it was not successful. if the number of rows in the file is about 2000[success.dat], it can be successfully imported. But for the data over about 4000 rows[fail.dat], it seems that several data at first of both converted energy and intensity are substituted by 0. column6.png shows intensity of ch6 vs energy_attained and I0.png shows intensity of I0 vs energy_attained. you can see this behavior. As a result, intensity cannot divide by I0, and data cannot be imported. if someone knows approach to solve this, could you teach me. Best regards, Yuji Hiraoka

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current-amp recommendation
by Matthew Marcus 14 Nov '17

14 Nov '17

I've gotten involved with a project in which stabilization of the position of a monochromatic, soft X-ray beam is needed. The offending frequencies seem to be vibration frequencies like 57 and 116Hz. We have in mind to use a thin Au film with a gap in the middle, measuring the drain current from the films, much as people normally use the jaws of slits. Now, I'd like to find a couple of current amplifiers which are small enough so that they can be connected with very short cables to the BNC connectors on the air-side of this detector, and which would have decent frequency response and low noise with inputs of the order of 0.1-1nA. Although this topic is outside the realm of XAFS analysis with IFEFFIT, I figure that people on this group might have some good experience. mam

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Re: [Ifeffit] Consult a few questions about XAS data analysis
by fred.mosselmans＠diamond.ac.uk 14 Nov '17

14 Nov '17

Hi Jun, Two points so Bruce doesn't get two upset. If you included the Athena project you used for the lcf and maybe an excel file of the results you got, then someone could Check what you did, as it is there is almost no way to offer an opinion on that. Bruce gave a course at Dimaond several years ago now, but most of what he shows is relatively as true as it was the day he said it. The videos can be found here. http://www.diamond.ac.uk/Beamlines/Spectroscopy/Techniques/XAS.html The VLC media player works well with them. Regards Fred J.F.W. Mosselmans Principal Beamline Scientist I18 Diamond Light Source Ltd Diamond House Harwell Campus Didcot OX11 0DE P + 44 1235 778568 M + 44 7785510211 E fred.mosselmans(a)diamond.ac.uk orcid.org/0000-0001-6473-2743 [cid:image002.png@01D27563.28EDA240] -- This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail. Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message. Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom

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Consult a few questions about XAS data analysis
by Jun Ge 14 Nov '17

14 Nov '17

Hi Bruce I'm a learner for XAS data analysis because of the need of scientific research. I have been to SLAC in San Francisco three times last year and collected some XAS data of samples and models in Beamline 7-3. This summer, I began to learn how to analyze these XAS data. My professor used to use WinXAS to analyze data. But this time he asked me to learn Athena. He thinks use two different softwares can double check the result. After the data pro-processing, including background remove and data normalization, etc., I save each spectrum in the form .txt. However, *in the same energy range and same file of sample and models, the result of LCF performed by WinXAS and Athena was totally different!* I try to solve this problem for a long time but no progress was made. So I turn to you and Ressler (the author of WinXAS) for help. I guess may be the algorithm is different between your Athena with WinXAS, but I'm not sure. With great experience in XAS data analysis, I think it's easy for you to solve this problem, isn't it? By the way,* I don't know how to fit the Coordination Number in another software called Artemis* in the software package of Demeter. I was told by Artemis that the coordination number can only be a number not alphabet. So I have no idea how to do this (yeah, I'm really a noob orz). And I don't know how to set the parameter more correctly to run a excellent Feff fit. So could you please help me? Finally,* I want to learn XAS data analysis systematically. So could you please recommend me some references like books or papers?* Anyway, thanks a lot for your help and your precious time! Sincerely, Jun Ge

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Re: [Ifeffit] Hephaestus: Absorption Data Source
by fred.mosselmans＠diamond.ac.uk 14 Nov '17

14 Nov '17

Hi Apologies for turning this into a social network, but Robert scanning Krause and Oliver, reminded me of when several decades ago, as a PhD student I typed all the K and L shell values from that paper into a table for Norman Binsted to use in his latest version of Excurve , probably Excurv88. Regards Fred -- This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail. Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message. Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom

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Hephaestus: Absorption Data Source
by Daniel Przyrembel 13 Nov '17

13 Nov '17

Dear All This might be a stupid question, but I have not been able to track this down myself: What is the data source of the "core-hole lifetimes" (i.e. the energy widths "gamma(ch)" in eV) of the "Absorption edges" in the "Absorption" panel of Hephaestus? As far as I could see these lifetimes/widths are not given in the 'Elam database'. Other XAS data tools based on the Elam database (like e.g. 'XrayDB') claim to be using values from 'O. Keski-Rahkonen and M. O. Krause, Atomic Data and Nuclear Data Tables 14, pp139-146 (1974) (http://dx.doi.org/10.1016/S0092-640X(74)80020-3)' for this. Because that reference does not give tabulated values but rough data plots only, it is difficult to compare those with the values in Hephaestus. If someone knows the respective data source used in Hephaestus, the answer/information is deeply appreciated! Best regards Daniel

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E0 in Co3O4
by Jesús Eduardo Vega Castillo 30 Oct '17

30 Oct '17

Dear list, I enclose an Athena project with a XAFS spectrum of Co3O4 with a metallic Co reference. Athena by default has chosen E0 at the absolute maximun of the derivative curve (at 7727.8eV) which in my opinion is too high because it is at the white line zone. I believe that E0 should be the previous maximun in the derivative at around 7722eV, which would be at the rising edge. Am I wrong? I would appreciate some help with the criterion to determine the right value. Yours, Jesús

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Re: [Ifeffit] iron carbide fitting with Artemis
by fred.mosselmans＠diamond.ac.uk 28 Oct '17

28 Oct '17

Dear Yunyun, I don't think Mike has written anything particularly incorrect , but he didn't point out why this approach is necessary. I believe there are two things you should definitely be aware of. An EXAFS dataset has a very limited amount of information. Approximately deltak.deltaR no of variables can be fitted To any spectrum as an absolute maximum and preferably quite a lot fewer than this (where deltak and deltaR are your fitted data range in k and R space respectively. Because of this if say you know you have N C atoms at ca G angstroms around your central atom. It is best not to use a variable for fit the degeneracy for that path but set it at the number you know is correct. And secondly because an EXAFS spectrum is effectively a collection of Sine waves there is a limited resolution, i.e. you cannot resolve paths of the same atom type that are less then Pi/2k(max) A apart, where k(max) is the maximum range of your dataset in k space, and Pi is Pi. Hence to separate two paths of the same atom that are 0.1 A apart you need about 15k worth of data. Regards Fred -- This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail. Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message. Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom

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iron carbide fitting with Artemis
by Yunyun Zhou 28 Oct '17

28 Oct '17

Hello All, I am having trouble fitting my sample with both Fe5C2 and Fe3O4 as standards. Hopefully somebody could help me out and I really appreciate it. My iron sample was mainly iron carbide in the core and iron oxide on the shell. Fe5C2 has a monoclinic structure and generated complicated FEFF paths. Many of the paths have similar distances. I have found some paper reported their results as follows, which apparently combined several paths together and assume they have similar path length. My first question is does someone know how they did it? It seems that combing similar paths makes fitting much easier, but I am not sure whether this is a correct way to do the fitting. My second question is regarding fitting with the two combined models of Fe5C2 and Fe3O4. I haven't fit with two models before. Is it just like what I did in the attached Artemis file? Shall there be any restrictions between the two models and do I have to fix some of the parameters? Thank you very much in advance for your help! Best, Yunyun Zhou Fe5C2 FEff paths: [image: Inline image 1] Literature reported results: [image: Inline image 2]

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monoclinic elemental selenium data
by George Sterbinsky 26 Oct '17

26 Oct '17

Hello, I am trying to help someone locate XAFS data collected from the red allotrope (monoclinic) of elemental selenium. Does anyone have a data set they are willing to share? Thank you, George

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