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

Ti data problem
by Siliang Chang 08 Aug '16

08 Aug '16

Dear all, I am new to XAFS data analysis. Im currently working on the XAFS data of atomic layer deposited mixed oxide thin film: SnTiOx. I have both Sn and Ti K edge data, and was able to fit Sn edge using a model of (Sn,Ti)O2 solid solution. However, Ti data really confuses me (please see attached file). With Rbkg set to 1, there is a doublet in 1-2 Å region in every data, this is something I have never seen in the literature. Im wondering if this is normal? Does this mean I should set a larger Rbkg value, say, around 1.5? Ive tried to fit the abovementioned Ti data using several models: anatase, rutile, (Sn,Ti)O2 solid solution, perovskite (N is fixed at 6 for all of those), so far no success. I would really appreciate if you can comment on my data processing, any suggestions are welcomed, as Im new to this, Im not sure if Im doing it the right way. Thank you very much. Best regards, Siliang Chang

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Converting PDF files to CIF files for usage in Artemis
by Ed Han 08 Aug '16

08 Aug '16

Dear All, In the upcoming fall, my research group plans on performing XAS studies observing the Hf L3-edge for various Hf-Al intermetallic samples. In preparation for the experiments, I am looking for CIF files of the various Hf-Al intermetallic systems, including HfAl3, HfAl2, Hf4Al3, etc. Upon scavenging through a multitude of crystallographic databases, I was not able to find any CIF files of Hf-Al intermetallics. However, I have acquired powder diffraction files (PDF) for said intermetallics. Seeing as how PDFs cannot be used in Artemis for EXAFS data analysis (to my knowledge), is there a way to convert PDFs into CIFs? I have attached one of the PDF files to demonstrate what information it contains. I would really appreciate your help! Regards, Edmund Han

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Amorphous
by Carlos Triana Estupinan 08 Aug '16

08 Aug '16

Dear Bruce I want to know if it is possible to obtain a 3D structure (.cif file) of an amorphous material from the EXAFS fitting carried out from artemis. I mean, there is a way to extract a .cif file with the structural data obtained from the refined spectra. Also, in amorphous materials there must be a distribution of interatomic bond distances and coordination, and so, how can I address such a structural distribitions. Regards.

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Multi-electron peak in Yb
by Matthew Marcus 05 Aug '16

05 Aug '16

Does anyone know of data on multi-electron peaks at the Yb L3 edge? One of the users here was just running Yb and finds on every spectrum a bump at the same energy. It's not a Bragg glitch from the sample or an I0 glitch or any other obvious artifact. It reminds me of the two little bumps at Ce. If someone has analyzed and parameterized this peak as a fraction of edge jump, then it would be possible to subtract it off. The attached papers show exmples for almost every lanthanide *execpt* Yb. For those doing Ce, I've written a program which does the correction, essentially as presented in the attached Gomilsek paper. Like Ce, Yb hs 2 valence states (other than 0), but the user is sure that his sample is all 3+. mam

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Re: [Ifeffit] Questions about fitting of EXAFS
by Scott Calvin 05 Aug '16

05 Aug '16

Just to clarify: the shape of the FT may certainly change when you change kmax. But if the data and the model change in the same way, then the fit is insensitive to the choice of kmax, in the sense that the fitted parameters remain stable to within their reported uncertainties. —Scott Calvin Sarah Lawrence College On Aug 4, 2016, at 2:50 PM, Fuxiang Zhang <zhangfx(a)umich.edu<mailto:zhangfx@umich.edu>> wrote: The Kmax effect on the shape of magnitude of FTs of one of my samples may come from the low signal/noise ratio.

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Questions about fitting of EXAFS
by Fuxiang Zhang 04 Aug '16

04 Aug '16

Hi, Everyone, I have several detailed questions about EXAFS processing and fitting 1. Are there any physical meaning for DeltaE0 in the paths, why it should be less than 10eV 2. The cutting range of Kmax (FT transform parameters) has great effect on FTs of EXAFS, how do I know to use the best value of Kmax; 3. How to make refinement equation for multi-scattering paths? Such as in NiFe alloys (simple fcc structure), the path [Ni-FM-3m] Fe1.1 Ni1.4 Fe1.1., I use 0.67*Efe+0.33*Eni for DeltaE0, and 0.67*ssFe1+0.33*ssNi4 for sigma2, is that right? Many thanks Fuxiang Zhang

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Applicable scope of delr=alpha*reff
by woschangqiang 03 Aug '16

03 Aug '16

Hi, everyone. delr=alpha*reff is very powerful in the fit of cubic system. And I want to know whether this function can be used in other crystal system. Thank for your patient answer.

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Reference spectra for brookite, anatase, rutile, Amorphous TiO2 at Ti K-edge
by Samy Ould-Chikh 03 Aug '16

03 Aug '16

Dear, I received some data at Ti K-edge to analyse. The spectra corresponds to samples which are different mixture of titania allotropes. I started to do standard EXAFS fitting, but it doesn't seem relevant in this case. Probably, an attempt to do linear combination fitting with brookite, anatase, rutile, and amorphous titania references will be more useful. Unfortunately, the set of data I was given do not include those standards. Is there anyone who have the spectra corresponding to those titania compounds and willing to share with us the raw data ? If yes, would you mind to provide also the citation I should you use to acknowledge those standards ? Many thanks for your kind help. Best Regards, Samy Ould-Chikh KAUST Catalysis Center Bldg.3,Level 4, #4231 4700 King Abdullah University of Science & Technology Thuwal 23955-6900 Kingdom of Saudi Arabia Tel: +966 12 8084486 E-mail: samy.ouldchikh(a)kaust.edu.sa Website: http://kcc.kaust.edu.sa/Pages/Home.aspx ________________________________ This message and its contents including attachments are intended solely for the original recipient. If you are not the intended recipient or have received this message in error, please notify me immediately and delete this message from your computer system. Any unauthorized use or distribution is prohibited. Please consider the environment before printing this email.

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2016 Introduction to Synchrotron Radiation Course
by Carlo Segre 01 Aug '16

01 Aug '16

This fall semester I will be offering an introductory graduate level course entitled Introduction to Synchrotron Radiation at Illinois Tech. This course has been offered on a regular basis over the past 5 years and it is avilable as an online course through IIT/Online. Through a special arrangement with the Dean of the College of Science, online students can take this course as non-degree students at a 67% tuition discount. We have had students from Italy and Brazil in past sessions of this course. Registering for this course as a non-degree student requires a simple application which can be completed online and will be approved in only a few days. The course description is below. Please share this with interested parties and direct any questions to Carlo Segre <segre(a)iit.edu> Course 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 Mondays and Wednesdays 17:00-18:15 and the lectures are available online as an Internet section for students not on the IIT campus or even in 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. For more information please contact Carlo Segre <segre(a)iit.edu> -- 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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Tenure-track academic position advert
by Robert Dryfe 01 Aug '16

01 Aug '16

Dear Sir/Madam, I would be grateful if you could circulate the details of an academic vacancy for an expert in the application of X-ray synchrotron techniques to chemical systems. Details can be found here (please note the application deadline is soon): https://www.jobs.manchester.ac.uk/displayjob.aspx?jobid=11764 Informal inquiries are welcome. regards, Robert Dryfe (School of Chemistry, University of Manchester, UK)

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