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

Re: [Ifeffit] Ifeffit Digest, Vol 80, Issue 7
by abhijeet gaur 10 Oct '09

10 Oct '09

Abhijeet, I took a quick peak at your project and I find it very confusing. In the most recent fit, you are fitting only from 3.5 to 4.4 -- the area under the *third* peak in the data. I don't really know how to comment on this project because you have set a large number of parameters to seemingly arbitrary values. From a numerical perspective, the reason for questions 1 and 2 is because you are attempting to fit only a narrow and of the data and you have set the majority of your parameters. That seems an unlikely strategy to me. I think the best thing you could do would be to fit *all* of your data rather than an arbitrary and small band of it. It would probably be fruitful for you to study carefully Shelly's example of analysis of SnO2 from her recent review chapter. See http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2008-July/003641.html and http://millenia.cars.aps.anl.gov/pipermail/ifeffit/2009-January/004012.html B -- 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 Hello Bruce sir, Thanks for your response. You must be talking about the 14th chapter of the book "Soil and Mineral analysis using XAS". I have that chapter with me. It is very explainatory one. with regards Abhijeet

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Mg K edge measurements
by Amitava D Roy 09 Oct '09

09 Oct '09

Our DCM beamline is capable of measuring magnesium K edge. Amitava Roy J. Bennett Johnston, Sr., Center for Advanced Microstructures and Devices Louisiana State University Baton Rouge, LA 70806 reroy(a)lsu.edu

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Fwd: Mg k-edge and Athena Questions
by Bruce Ravel 08 Oct '09

08 Oct '09

I am forwarding this message to the Ifeffit mailing list, which is the proper forum for Ifeffit software support. Please see http://cars9.uchicago.edu/iffwiki/BruceRavel/FormLetters/HelpRequest I have some comments, which I will post once this gets distributed by the mailing list. ---------- Forwarded Message ---------- Subject: Mg k-edge and Athena Questions Date: Wednesday 07 October 2009 From: fang.fang(a)yale.edu To: bravel(a)bnl.gov Dear Bruce, This is Fang from Yale University, Pfefferle and Haller's group. Besides our research on Co/Pt on your X23A2 and X18B, I am mainly involved in the Mg and B edge measurement. I heard from Paul that you also have anongoing project on Mg k-edge, and the updated Athena could import the raw data from X15B. However, after I installed the most recent version of Ifeffit and installed, they still don't recognize the data file. Could you show me how to import the data? Your help will be greatly appreciated. There is another question come with the seasonal shut down of X15B. Do you know any other active beamlines who are willing to put in the effort to scan Mg k-edge? Since NSLS asked us to put in a substitute beamline after we put in this year's proposal, we thought you might have a much better idea of which beamline to turn for this hard range around 1300eV. Many thanks again, Fang ------------------------------------------------------- -- 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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First shell resolution
by Eugenio Otal 08 Oct '09

08 Oct '09

Hi Bruce, thanks for the help, it was really useful. Regards, euG

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First shell resolution
by Eugenio Otal 08 Oct '09

08 Oct '09

Hello, I have a very noisy signal so I have a relative good signal until k =9. I am trying to fit the first shell and want to know if there are a limit for the subshells resolution if the signal is unavailable for k larger than 9. Regards, euG

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Br K-edge exafs spectrum of NaBr(s) or KBr(s)
by Gleb Pokrovski 08 Oct '09

08 Oct '09

Hello, I'm looking for a good exafs spectrum in transmission mode at Br K-edge of NaBr or KBr solids at ambient or low-temperature conditions. Any help will be referenced and acknowledged. Thanks in advance Gleb

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Tenure track position for chemist
by Scott Calvin 06 Oct '09

06 Oct '09

Hi all, Since presumably a lot of people on this list know early-career chemists with an interest in a position where teaching is valued and they can also collaborate closely with a XAFS expert (that's me, I guess), I thought I'd pass along information on our opening: > Sarah Lawrence College, a coeducational liberal arts college > dedicated to individualized education, invites applications from > broadly trained chemists for a tenure-track position beginning > August 1, 2010. The successful candidate will teach general > chemistry, other undergraduate chemistry courses of interest to > liberal arts students, and upper-level courses including physical > chemistry. An interest in environmental science is desirable. A > commitment to working closely with students on an individual basis > is essential. Candidates should have a Ph.D. in Chemistry or expect > to receive one by August 1, 2010. > > Application materials must include: cover letter, CV, statement of > teaching philosophy and research interests, graduate transcript, > descriptions of two courses suitable for liberal arts students, and > three letters of recommendation (at least one of which must address > the candidate's ability to teach general chemistry). Deadline for > applications is November 16, 2009. To apply for the position please > go to: > > https://slc.simplehire.com/applicants/jsp/shared/frameset/Frameset.jsp?time… > For information on Sarah Lawrence College, our curriculum, teaching > methods, and philosophy of education, please see our Web site at: http://www.slc.edu > . > SLC is an Equal Opportunity Employer committed to achieving a > racially and culturally diverse community. --Scott Calvin Sarah Lawrence College

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Re: [Ifeffit] Ifeffit Digest, Vol 80, Issue 1
by Hashem Stietiya 02 Oct '09

02 Oct '09

Thank you Dr. Segre, So I should not be skeptical if my fitting results return a high Debye Waller value for my first shell as compared with the second shell. I appreciate your help. Hashem Stietiya On Fri, Oct 2, 2009 at 12:00 PM, <ifeffit-request(a)millenia.cars.aps.anl.gov>wrote: > Send Ifeffit mailing list submissions to > ifeffit(a)millenia.cars.aps.anl.gov > > To subscribe or unsubscribe via the World Wide Web, visit > http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit > or, via email, send a message with subject or body 'help' to > ifeffit-request(a)millenia.cars.aps.anl.gov > > You can reach the person managing the list at > ifeffit-owner(a)millenia.cars.aps.anl.gov > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Ifeffit digest..." > > > Today's Topics: > > 1. Debye Waller for first shell and second shell (Hashem Stietiya) > 2. Re: Debye Waller for first shell and second shell (Carlo Segre) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 2 Oct 2009 11:04:45 -0500 > From: Hashem Stietiya <mstiet2(a)tigers.lsu.edu> > Subject: [Ifeffit] Debye Waller for first shell and second shell > To: ifeffit(a)millenia.cars.aps.anl.gov > Message-ID: > <c7b8f940910020904ged84c20t305a742484dd1f4b(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Dear All, > > Does the Debye Waller value for the first shell have to be smaller than > that > of the second shell? can you have a situation where the Debye Waller value > for the Zn-O first shell is 0.011 and for the Zn-Fe second shell is 0.003? > so if there is thermal or static disorder in the first coordination > shell,that must be the case for the second coordination shell? > > Best Regards, > > Hashem Stietiya > Louisiana State University >

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Debye Waller for first shell and second shell
by Hashem Stietiya 02 Oct '09

02 Oct '09

Dear All, Does the Debye Waller value for the first shell have to be smaller than that of the second shell? can you have a situation where the Debye Waller value for the Zn-O first shell is 0.011 and for the Zn-Fe second shell is 0.003? so if there is thermal or static disorder in the first coordination shell,that must be the case for the second coordination shell? Best Regards, Hashem Stietiya Louisiana State University

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Cementite EXAFS
by Andrew 25 Sep '09

25 Sep '09

Bhoopesh, I would trust the XAFS.org spectrum more than mine, I'm sure that the APS has a better resolution etc. I'm aware that there are other forms of reduced iron carbide, but I did nothing special except for following the Li et al. paper. I then tried to see if the spectrum was similar to both the one on Dr. Newville's database as well as the Iglesia and coworkers' papers, and they were. I know this data is a bit glitchy... and I was pretty much only interested in the XANES. If the person that Dr. Newville is referring to made the Fe3C from the iron melt it would have been a white powder, so they likely did a similar procedure as reducing the Fe2O3 std. to a sufficient temperature (at 1 atm). I have also heard from a former Exxon researcher that when they wanted to make cementite they simply CO reduced Fe2O3 to a sufficient temperature as well. I'm forwarding this directly to your e-mail as well. Hope this helps, if not (try and comparing it with the one on the XAFS.org, I remember when I checked it was similar). Andrew Campos

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