[Ifeffit] S XANES question

[Matthew Marcus]

Yup, that's what mine looks like, if done with TEY to avoid overabsorption.  For calibration, I use FY and take the peak position as
the calibration.  Yours also looks tolerably like the apatite spectrum in the cited paper (copied here:
file:///C:/Users/admin/Downloads/02e7e526633b903125000000%20(1).pdf), figure 1.  It does not look like their
gypsum spectrum.
	mam

On 11/26/2014 2:30 PM, Matt Newville wrote:
> Hi Matthew, Lyle,
>
> I'm still learning S XANES, but when we've measured gypsum, it looks very comparable to the spectra from ID21:
> http://www.esrf.eu/UsersAndScience/Experiments/Imaging/ID21/php/gypsum
>
> We often use the spectra from there as references (or when asking: Is this "standard" what we think it is?)
>
> --Matt
>
>
>
> On Wed, Nov 26, 2014 at 4:23 PM, Matthew Marcus <mamarcus at lbl.gov <mailto:mamarcus at lbl.gov>> wrote:
>
>     The gypsum spectrum looks nothing like any spectrum of gypsum or other sulfate I've ever seen.  I'm deeply suspicious.
>              mam
>
>     On 11/26/2014 1:36 PM, Lyle Gordon wrote:
>
>         Matthew,
>
>         Paris et al in 2001 reported higher S K-edge white line energies for SO4 in Apatite, 2 eV above Gypsum.
>
>         THE VALENCE AND SPECIATION OF SULFUR IN GLASSES
>         BY X-RAY ABSORPTION SPECTROSCOPY
>         The Canadian Mineralogist
>         Vol. 39, pp. 331-339 (2001)
>
>         -Lyle
>
>         On Wed, Nov 26, 2014 at 12:39 PM, Matthew Marcus <mamarcus at lbl.gov <mailto:mamarcus at lbl.gov> <mailto:mamarcus at lbl.gov <mailto:mamarcus at lbl.gov>>> wrote:
>
>              A user on ALS 10.3.2 is taking S K-edge XANES and consistently finding a strong peak at 2484eV (calibration: gypsum white line = 2482.75eV).
>              There's a shoulder at the nominal position of the sulfate peak.  Now, peaks below sulfate I can understand, but since there's no such
>              thing as heptavalent sulfur, what could give a peak *above* the sulfate white line?  Anybody ever seen that?  Yes, we checked calibration.
>                       mam
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