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.


On 22 Apr 2023, at 12:14 pm, Robert Gordon <ragordon@alumni.sfu.ca> 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:
Capillary is silica glass :-)

On 22 Apr 2023, at 11:57 am, Anatoly Frenkel <anatoly.frenkel@stonybrook.edu> wrote:

Capillary made or what?

Anatoly

On Apr 21, 2023, at 9:52 PM, Joel Brugger <joel.brugger@monash.edu> wrote:

 Fluo, 0.5 wt% Cu.

On 22 Apr 2023, at 11:41 am, Anatoly Frenkel <anatoly.frenkel@stonybrook.edu> wrote:

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

Anatoly

On Apr 21, 2023, at 9:31 PM, Joel Brugger <joel.brugger@monash.edu> 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
Clayton, Victoria 3800
Australia

T: +61 3 9905 4898
E: Joel.Brugger@monash.edu 
Twitter: @JoelBrugger

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