Re: [Ifeffit] Interpreting old XANES data with missing standards

Hi Don, I am sure you are aware but I would like to remind you that the sulfides that you are working with have serious potential for self absorption. Most spectra out there have different degrees of self absorption which can really mess up LCA type analysis. This is not a quick solution, but you might consider remeasuring the standards following a strict protocol of sample dilution, grinding and deposition on substrate to minimize any such artifacts. Best, Riti Sarangi Sent from my iPhone

On Jun 8, 2018, at 7:45 AM, Carlo Segre wrote:

You might also ask the beamline scientist at APS Sector 9, Tianpin Wu

carlo

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On Fri, 8 Jun 2018, Anatoly Frenkel wrote:

Don,

I am sure that Paul Northrup (northrup@bnl.gov) will help - he was the beamline scientist at X15B and is likely to have the standards you need.

Anatoly

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On Fri, Jun 8, 2018 at 9:54 AM, Don Baker wrote:

Hello All,

First let me apologize if the question below is inappropriate for this group, but I don't know of a better set of experts that I can ask.

So, here is some background:

I have some old S K-edge XANES data from NSLS X15B for S-bearing silicate glasses that was collected by a Ph.D. student who decided to leave for a good job rather than finishing their degree. During my current sabbatical year I have been looking at the data and reading papers on the topic. I think that I now understand, at least qualitatively, the changes in the spectra as a function of iron concentration in the glasses, but to perform quantitative modelling I need XANES spectra of MgS and CaS, which we did not think to collect all those years ago. I have searched for XANES spectra of MgS and CaS on the CARS XAFS Data Library and on the XAFS Database at IIT without success. I am unaware of other databases available.

Now for for my questions:

1. Does anyone know of a XANES database that contains MgS and CaS spectra? (Or did I miss it in the databases I searched?)

2. If I cannot find measured MgS and CaS spectra, what do you think about using calculated spectra (e.g., Zheng et al.,2012, NPJ Computational Materials, 12 -- which uses FEFF) for quantitative modelling?

And information, ideas, and suggestions that you may have will be appreciated.

Wishing you all the best from a spring morning in Montreal,

Don

-- Melting rocks today for a better tomorrow . . . Don R. Baker, Professor of Geochemistry, Earth and Planetary Sciences, McGill University

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-- 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@iit.edu http://phys.iit.edu/~segre segre@debian.org _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit Unsubscribe: http://millenia.cars.aps.anl.gov/mailman/options/ifeffit