HI Samuel,
You might be interested to look at experiments Paul Magyar did with N2O on alumina, which he showed establishes site-specific and ‘clumped’ isotope equilibrium on laboratory time scales at temperatures on the order of 100 C. I suspect the most complete description of this work is in his PhD thesis, which can be found through the Caltech library web site:

https://thesis.library.caltech.edu/10212/

I think these experiments are summarized as well in the following paper:

Measurement of rare isotopologues of nitrous oxide by high‐resolution multi‐collector mass spectrometry
PM Magyar, VJ Orphan, JM Eiler
Rapid Communications in Mass Spectrometry 30 (17), 1923-1940

good luck!

John

On Jun 8, 2020, at 6:31 AM, Samuel Bodé <[log in to unmask]> wrote:

Dear Coleagues,
 
Years ago we diluted highly 15N labelled N2O with ‘natural’ N2O to make it measurable with our IRMS. We realised that of course the mixed N2O was not at stochastic equilibrium and could thus not trust the δ15N reported by the instrument but should compute it from the raw 45/44R and 46/44R data assuming ‘normal’ 18O and 17O. We however also observed that samples left for a couple of days tended to move toward that equilibrium. At the time, I thought that measuring the N exchange rate in N2O (which I expect to be different for the alfa and beta position) would be a nice little experiment to do in my spare time. However more than 10 years later, I still did not find that spare time. 
Now for a new labelling experiment where we are particularly interested in the preferential formation 15N15NO I wonder again how quickly the N of N2O can exchange.
Did some of you determine (or has rational to have an idea of) the exchange rate of N between N2O molecules?
Thank you for sharing your thoughts. 
 
Sincerely yours,
 
 
Samuel
 
 
 
Dr. Samuel Bodé
Lab Manager ISOFYS
T +32 9 264 58 64
 
ISOTOPE BIOSCIENCE LABORATORY (ISOFYS)
Department of Green Chemistry and Technology
Ghent University
 
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