Re: [Ifeffit] SO2 for samples with non-planar geometry

Didn't take the ln of the FLY by chance? ...after processing foil in transmission? just trying to think of anything else dead time of the FLY detector? (solid state assumed...DT correction applied?) -R. On 2023-04-21 7:31 p.m., Joel Brugger wrote:

Thanks Rob.,

Good thought, but definitively Cu++; we get the right energy shift and the right shape for XANES (linear Cu+ is very distinctive). We actually maintain nice oxidising conditions (4 bar of air applied to the capillary), and the spectra were stable over time (slew scan mode, with ~5 minutes per scan, and 10 scans collected).

Note that Cu+ is not stable in solution unless you give it a ligand such as chloride; reduction to Cu+ in our solution most likely would result in precipitation of Cu(0) via disproportionation. No evidence for this at all.

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On 22 Apr 2023, at 12:14 pm, Robert Gordon wrote:

Hi Joel,

How much edge shift are you seeing between your foil and the solution? Cu+2 is about 4.5 eV up from Cu metal...you seeing about that much?

Cu+2 can photoreduce...I know Cu+(aq) isn't stable, but maybe some complex is forming? Just a thought...CN=2 and I think linear Cu+

-R.

On 2023-04-21 6:58 p.m., Joel Brugger wrote:

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Capillary is silica glass :-)

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On 22 Apr 2023, at 11:57 am, Anatoly Frenkel wrote:

Capillary made or what?

Anatoly

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On Apr 21, 2023, at 9:52 PM, Joel Brugger wrote:

 Fluo, 0.5 wt% Cu.

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On 22 Apr 2023, at 11:41 am, Anatoly Frenkel wrote:

Fluorescence or transmission? What is the Cu concentration? Could be self absorption.

Anatoly

> On Apr 21, 2023, at 9:31 PM, Joel Brugger > wrote: > >  Dear list, > > We are trying to fit EXAFS from data collected on solutions > within a capillary. The capillary has OD 1mm, ID 0.8mm, and was > placed horizontally. The beam is 1x2 mm (VxH). > > Fitting the copper reference foil, we get the expected SO2 value > of ~0.7. > > However, the solution containing the Cu(II) aqua ion gives a > coordination of 2, instead of the expected 5-6. So our SO2 for > this solution is apparently ~0.25. > > I couldn’t find a discussion of the effect of geometry (in our > case cylindrical rather than planar) on SO2. Is it possible that > the low SO2 is a result of the odd geometry? > > Confused as ever, > > JOEL > > > *Joël Brugger* > Professor of Synchrotron Geosciences > > *Monash University* > School of Earth, Atmosphere and Environment > Room 257A, Level 2, 9 Rainforest Walk x-apple-data-detectors://2 > Clayton, Victoria 3800 x-apple-data-detectors://2 > Australia x-apple-data-detectors://2 > > T: +61 3 9905 4898 tel:+61%203%209902%209095 > E: Joel.Brugger@monash.edu mailto:Andrew.Mackintosh@monash.edu > Twitter: @JoelBrugger > > _______________________________________________ > 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 _______________________________________________ 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

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