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

Differences between fluorescence and transmission of the same sample
by Andrew Campos 05 May '10

05 May '10

Hi everyone, My lab mates are running in-situ H2 reduction of Cobalt/SiO2 catalysts using the Co K-edge and are obtaining differences between the fluorescence and transmission signals. The in-situ cell does have quite a bit of sample thickness (2-3 mm approx) and I was wondering if the fluorescence signal only has a penetration depth of a few micrometers. If this is the case that would explain it where the side that is further away from the heating element is more oxidized than the rest of the sample. Has anyone run into this problem before? We're using the basic furnace/cryostat unit (in-situ cell manufactured by the exafsco) and a 13 element fluorescence detector (germanium diode). I appreciate any insight into the issue, I have attached a fluorescence and transmission spectrum collected at the same time where the transmission and fluorescence are in the .prj file. Thanks so much! Andrew

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expected network outage to millenia.cars.aps.anl.gov
by Matt Newville 04 May '10

04 May '10

Hi Folks, The APS networking people will be doing some hardware work next week which means that millenia.cars.aps.anl.gov will be inaccessible to the outside world May 10,11,12, and 17. Because of this, xafs.org, the Ifeffit wiki, and this mailing list will all appear to be down on these days. --Matt

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S02 parameter
by Enzo Liotti 04 May '10

04 May '10

Hello, I'm trying to use EXAFS to study the intermetallics present in a complex Al alloy. The three main phases present in the alloy are Al3Ti, Al13Cr2 and Al13Fe4. The first is tetragonal and the other two are monoclinic. To create the theoretical model in Artemis I inserted in Atoms the crystallographic informations available in literature and I run it and FEFF. Since in the monoclinic structure the absorbing atom occupies more than one position I created as many FEFF calculations as the number of positions of the Absorbing atom changing every time the core atom in the Atoms page. My question now regards the S02 parameter (path amplitude), how do I model it when I've got more than one FEFF calculation for a single compound? and how do I do when I have more than one compound with more than one FEFF calculation each ones (for example if I have a mixture of two similar intermetallics like Al3Ti and Al11Ti5 )? Best regards Enzo

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fitting simultaneously two different K-edges
by María Elena Montero Cabrera 03 May '10

03 May '10

Dear friends, Sam Webb, Bruce Ravel or any other, I have XAFS measurements, performed at SSRL at room temperature, of three compounds. All compounds have multielemental character and I have K-edge XAFS of two elements in each compound. It is desirable to make IFEFFIT fitting of both edges simultaneously. In all cases random solution of competing elements is assumed, but there are ferroelectricity, superconductivity or magnetic behaviors that are desirable to be explained. In each case, XAFS would confirm or reject the random character of the solution. I am not such an expert for resolving by myself how to fit together two edges using Artemis software. I'll present each case in the following: 1. rutheno-cuprate (Ru1-xNbx)Sr2Eu1.4 Ce0.6Cu2O10+δ compounds series was studied in both Ru and Nb K-edges. Changes in interatomic distances that could be obtained by EXAFS would tell something about oxygen octahedra around Ru and Nb. 2. g-Fe1-xCrxO3 maghemite for x=0.25, 0.5 and 0.75 was investigated by XAFS in both Fe and Cr K-edges. Possible distortion of oxygen octahedra around both Fe(III) and Cr(III) cations would tell something about not confirmed ferroelectricity. 3. LaFeNiTiO3 has been confirmed to display magnetic behavior and was studied by its Fe and Ti K-edges. Interatomic distances that could be obtained by EXAFS are interesting for checking possible preferential occupation of sites by Fe or Ti atoms. Would any of you, please, suggest how to use Artemis or Sixpack for solving these problems? Sincerely yours -- María Elena Dra. María Elena Montero Cabrera Departamento de Medio Ambiente y Energía Centro de Investigación en Materiales Avanzados (CIMAV) Miguel de Cervantes 120, Compl. Ind. Chihuahua Chihuahua CP 31109, Chih. México Tel (614) 4391123

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Unreasonable Fits on one of my computers in Artemis (Mac)
by Stefan Mangold 02 May '10

02 May '10

Dear List, I have produced a fit with 2 structure, which went reasonable well. So I saved the Artemis file on the first maschine (a MacPro with 20 Gb Ram). Made with "Artemis 0.8.011 using darwin, perl 5.008009, Tk 804.028, and Ifeffit 1.2.10". Switched to a MacBookPro at home and copied the Artemis-file over (Same version Artemis 0.8.011 using darwin, perl 5.008009, Tk 804.028, and Ifeffit 1.2.10) and got a completely different result. Did I anything unreasonable by just copying the file over an think to proceed? Did I missed anything? Since the experiment is rather small (1.2 Mb) it should not be a memory issue? Thanks for any help or advice? Regards Stefan Mangold

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Re: [Ifeffit] SixPack PCA (Andrew)
by fred.mosselmans＠diamond.ac.uk 01 May '10

01 May '10

-----Original Message----- From: ifeffit-bounces(a)millenia.cars.aps.anl.gov [mailto:ifeffit-bounces@millenia.cars.aps.anl.gov] On Behalf Of ifeffit-request(a)millenia.cars.aps.anl.gov Sent: 30 April 2010 18:00 To: ifeffit(a)millenia.cars.aps.anl.gov Subject: Ifeffit Digest, Vol 86, Issue 15 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..." Hi I am even less of an expert but think Andrew has misread the Beauchemin paper as you want a low Spoil. They say <3 is good and more than 6 rotten. Cheers 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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SixPack PCA
by Andrew 29 Apr '10

29 Apr '10

Nagappan, I'm by no means a statistical expert. There are some rules of thumbs in the literature regarding what Spoil value to believe in or not. Some resources that you can look up: 1. Beauchemin, S.; Hesterberg, D.; Beauchemin, M., Soil Sci Soc Am J 2002, 66 (1), 83-91. (( in the above work they included standards which had SPOIL values greater than 6, so they would have rejected a standard with a value lower than 6)) 2. Malinowski, E. R., Factor Analysis in Chemistry. Wiley: New York, 2002; p 432. I might be wrong on this but when these programs use the formulas for calculating F-values and SPOIL values, they assume that all points are independent. One question that comes up sometimes is "How many independent points are there in a XANES spectrum?" In EXAFS many people use the Nyquist criterion. And what I'm getting at is you have to be cautious in using a rule of thumb for the XANES analysis. If there are other techniques you can use to help you identify what is in your sample try those as well. The manual on Athena also points out that the number of independent points collected in a XANES spectrum is difficult to determine. Without additional information: the quality of the data collected (the signal-to-noise), what edge you collected your spectra, are you fitting standards that you collected in the same set of runs as your samples, I think it's difficult for anyone to go into further depth. Please look up the above two references, this should at least give you a better idea. Hope this helps! Andrew Campos

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SixPack PCA
by Nagappan Ramaswamy 29 Apr '10

29 Apr '10

Hello, In the Target Transform step of PCA analysis using the SixPack program, I am trying to understand the significance of the parameter called SPOIL? Can this parameter can be used as a measure of merit of the target? If so, what range is acceptable. Also what does it mean if SPOIL value is zero? Thanks Nagappan

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SixPack PCA
by Nagappan Ramaswamy 29 Apr '10

29 Apr '10

Hello, In the Target Transform step of PCA analysis using the SixPack program, I am trying to understand the significance of the parameter called SPOIL? Can this parameter can be used as a measure of merit of the target? If so, what range is acceptable. Also what does it mean if SPOIL value is zero? Thanks Nagappan

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Deadline extended - North American Core Shell Spectroscopy Conference
by Carlo Segre 27 Apr '10

27 Apr '10

Hello All: Please share this announcement with anyone whom you feel might be interested. I am positive that I am not getting this out to the entire core shell spectroscopy community. Note hat the abstract deadline has been extended until May 15 for oral presentations. The Ed Stern Symposium will feature the following invited speakers: Dr. Mali Balasubramanian, Argonne National Laboratory Prof. Jerry Seidler, University of Washington Prof. Anatoly Frenkel, Yeshiva University Dr. Ken Kemner, Argonne National Laboratory Prof. John Rehr, University of Washington Prof. Michael Paesler, North Carolina State University other invited speakers will include Dr. Corwin Booth, Lawrence Berkeley National Laboratory Prof. James Penner-Hahn, University of Michigan and more to come... ---- Conference Announcement ---- 1st North American Core Shell Spectroscopy Conference to be held jointly with the 59th Denver X-ray Conference 2-6 August 2010 Ι Denver Marriott Tech Center Hotel, Denver, CO <https://resweb.passkey.com/Resweb.do?mode=welcome_ei_new&eventID=1454471> The first North American Core Shell Spectroscopy Conference will be held jointly with the 59th Denver X-Ray Conference, 2-6 August 2010. The conference will feature poster sessions as well as oral presentations and students, in particular are encouraged to participate with oral presentation submissions. All topics relating to core shell spectroscopy are welcome, including: · X-ray Absorption Spectroscopy · X-ray Fluorescence Spectroscopy / Fluorescence Mapping · Resonant Inelastic X-ray Scattering / X-ray Raman Scattering · X-ray Magnetic Circular Dichroism The conference will feature a special session and dinner in honor of Ed Stern. The list of invited speakers for this special session includes Dr. Mali Balasubramanian, Argonne National Laboratory Prof. Jerry Seidler, University of Washington Prof. Anatoly Frenkel, Yeshiva University Dr. Ken Kemner, Argonne National Laboratory Prof. John Rehr, University of Washington Prof. Michael Paesler, North Carolina State University Participants will be able to attend Denver X-Ray Conference Sessions being held in adjacent rooms. Details of the oral presentation sessions will be posted on the DXC web site <http://www.dxcicdd.com/default.htm> as they are available. Students are able to register for a reduced cost, are eligible for special student room rates <http://www.dxcicdd.com/10/details.htm#studentrooms>, and may apply for funding <http://www.dxcicdd.com/10/files/2010-DXC-Student-Travel-Grant-application.p…> to attend the conference. Abstract submissions for oral presentations will be open until May 15 and can be made on the Denver X-Ray Conference web site by selecting the "Submit Abstract for the Joint Meeting with the North American Core Shell Spectroscopy Conference" link on the left side of the page (the 8th button down) or directly at the abstract submission page <http://www.dxcicdd.com/cssc/cssc_abstract.asp>. For more information, visit http://www.dxcicdd.com or contact: Denise Flaherty, Conference Coordinator flaherty(a)icdd.com<mailto:flaherty@icdd.com> ICDD 12 Campus Boulevard Newtown Square, PA 19073 -- 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 ---------- Forwarded message ---------- Date: Thu, 15 Apr 2010 08:36:48 -0500 (CDT) From: Carlo Segre <segre(a)iit.edu> To: ingrid.pickering(a)usask.ca Subject: Invitation to speak at the North American Core Shell Spectroscopy Conference Dear Prof. Pickering: The first "North American Core Shell Spectroscopy" conference will take place this year concomitantly with the Denver X-ray conference August 2-6, 2010. We are organizing this conference to provide an opportunity for researchers in North America to gather and present their research in years when there is no International XAFS Conference. One of the major goals is to have a high degree of participation from students and postdoctoral scientists in both the oral and poster sessions. On behalf of the organizing committee, I would like to invite you to give a talk at one of our sessions. Since we are leaving the logistical organization of this conference to the ICDD Conference Staff, we can offer the same reduced registration fee that is provided to the Denver X-ray Conference invited speakers. The plans for the conference include a symposium in honor of Ed Stern on Tuesday, August 3, a poster session and a series of oral sessions running concurrently with the Denver X-ray Conference sessions. We hope that you can accept this invitation, and look forward to seeing you in Denver. Sincerely yours, Carlo Segre, for The Organizing committee. -- 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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