[Ifeffit] SO2 for samples with non-planar geometry

Fri Apr 21 21:31:29 CDT 2023

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 at 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 at stonybrook.edu <mailto:anatoly.frenkel at stonybrook.edu>> wrote:
>>> 
>>> Capillary made or what?
>>> 
>>> Anatoly
>>> 
>>>> On Apr 21, 2023, at 9:52 PM, Joel Brugger <joel.brugger at monash.edu <mailto:joel.brugger at monash.edu>> wrote:
>>>> 
>>>>  Fluo, 0.5 wt% Cu.
>>>> 
>>>>> On 22 Apr 2023, at 11:41 am, Anatoly Frenkel <anatoly.frenkel at stonybrook.edu <mailto:anatoly.frenkel at 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 at monash.edu <mailto:joel.brugger at 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 <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 at monash.edu <mailto:Andrew.Mackintosh at monash.edu> 
>>>>>> Twitter: @JoelBrugger
>>>>>> 
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