High Xenon Density Optical Pumping

The signal intensity levels off at a xenon pressure of about 200 kPa. However, this is true only if the overall pressure is still balanced by helium to about 700 kPa. 

If only pure xenon is used (not depicted) the signal intensity levels off at about 500 kPa. The situation is again different when the xenon pressure is reduced after the optical pumping procedure to about ambient pressure in order to be added to 

The in situ monitoring of high temperature reactions by hpl29Xe magnetic resonance is still in its infancy. Although the previous work on gas phase dynamics in porous media has shown the feasibility of dynamic microscopy and M RI and the first in situ combustion NMR spectra have been collected, much more development remains to be done. To date, hpl29Xe NMR and MRI are currently the only techniques available to study gas dynamics in porous and opaque systems. 

Abragam 1961, The Principles of Nuclear Magnetism, Clarendon Press, Oxford. 

Barrie, J. Klinowski 1992, Prog. Nud. Magn. Reson. Spectrosc. 24, 91-108. 

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Fig. 5.3.8 Photograph of the detection region of the NMR probe with radiofrequency coil. A methane—air mixture was ignited above the zeolite pellets. The mixture also contained xenon for NMR detection. Hp-129Xe NMR spectra with 30% xenon (from high-density xenon optical pumping) in 70% methane is depicted. (1) The spectrum in the absence of combustion and (2) the spectrum during combustion. Adapted from Ref. [2],...

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