[Ifeffit] Solid AuCl EXAFS fitting – big N

[Sin Yuen Chang]

Dear Dr. Pokrovski,

Thank you very much. Your data is very useful.

And what a coincidence, I just found your paper a few days ago!

Best wishes,
Sin-Yuen

From: ifeffit-bounces at millenia.cars.aps.anl.gov [mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf Of Gleb Pokrovski
Sent: 30 June 2014 08:18
To: XAFS Analysis using Ifeffit
Subject: Re: [Ifeffit] Solid AuCl EXAFS fitting – big N

Dear Sin-Yuen,

Your Au(I)Cl seems to be significantly oxidized to HAu(III)Cl4.
It can be judged by the pronounced pre-edge feature at ~11921 eV.

I added a few (likely good) spectra of Au(III) and Au(I) chloride reference compounds
to your athena file (attached), together with the  paper in which they were published.

My AuCl(s) looks much less oxidized than yours, but still might be somewhat altered;
the best Au(I)Cl2 reference, to my opinion, is the aqueous AuCl2(-) complex which is stable
in acidic Cl solutions at elevated temperatures (included in the file).
Please feel free to use these spectra by referring to the paper attached.

best regards

Gleb




Dr. Gleb S. Pokrovski

Directeur de Recherche CNRS

Associate Editor of Economic Geology

Associate Editor of Geochimica et Cosmochimica Acta

Geosciences Environnement Toulouse (ex-LMTG)

GET - UMR 5563 of CNRS, University of Toulouse III

14 avenue  Edouard Belin , F- 31400 TOULOUSE, France

e-mail: gleb.pokrovski at get.obs-mip.fr<mailto:gleb.pokrovski at get.obs-mip.fr>; glebounet at gmail.com<mailto:glebounet at gmail.com>

phone: 33-5-61-33-26-18 , fax: 33-5-61-33-25-60
On 27/06/2014 20:11, Sin Yuen Chang wrote:

Many thanks for the response, Bruce.



For something as tricky as Au(1+) chloride, I think it is unwise to

blindly trust data that you found in some disreputable corner of the

internet.  It really seems like the kind of thing you need to measure

for yourself if you want confidence in what you have.



Exactly what I am working on!



Best regards,

Sin-Yuen



-----Original Message-----

From: ifeffit-bounces at millenia.cars.aps.anl.gov<mailto:ifeffit-bounces at millenia.cars.aps.anl.gov> [mailto:ifeffit-bounces at millenia.cars.aps.anl.gov] On Behalf Of Bruce Ravel

Sent: 27 June 2014 16:40

To: XAFS Analysis using Ifeffit

Subject: Re: [Ifeffit] Solid AuCl EXAFS fitting – big N



On 06/27/2014 01:14 AM, Sin Yuen Chang wrote:

Given how many times AuCl XANES has been published before, has anyone

else perhaps run into this problem? Has anyone perhaps measured solid

AuCl under exclusion of moisture and air, or several times as a

function of time to assess beam damage?





I was under the impression that *everyone* runs into that problem.  As you say Au(1+) chloride is quite unstable.  Given that the white line in the data that you took from my LCF fitting example is so close in size to that of Au(3+) chloride, I would guess that the sample was no pure Au(1+) by the time we measured it.



For something as tricky as Au(1+) chloride, I think it is unwise to blindly trust data that you found in some disreputable corner of the internet.  It really seems like the kind of thing you need to measure for yourself if you want confidence in what you have.



B



--

  Bruce Ravel  ------------------------------------ bravel at bnl.gov<mailto:bravel at bnl.gov>



  National Institute of Standards and Technology

  Synchrotron Science Group at NSLS --- Beamlines U7A, X24A, X23A2

  Building 535A

  Upton NY, 11973



  Homepage:    http://xafs.org/BruceRavel

  Software:    https://github.com/bruceravel

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