Equipment, AAP 2018-2
Project leader: Flavien GUENNEAU
The objective of this project is to update and bring new features to the xenon hyperpolarization device that was home-built by our team more than 15 years ago. The aim is not only to increase the performance, stability and reliability of the setup but also its versatility. The applications foreseen by the partners deal with the characterization of novel porous catalysts based on modified zeolites, chiral mesoporous materials or metal-organic frameworks (MOFs), and with the understanding of porosity in clay materials hosting various molecules.
The use of 129Xe NMR spectroscopy to study porous materials is now a well-established since the chemical shift of adsorbed xenon is highly influenced by several factors such as the size of the cavities, metal ions or particles, surface heterogeneity, structural defects or coadsorbed phases.
Sensitivity improvement by hyperpolarization of 129Xe via optical pumping extended the use of xenon NMR to materials with low surface area, long relaxation time or in very small quantity. Our lab has been developing its own setup since 2001. It has the capacity to work in closed-loop, enabling to recirculate the gases for accumulation purposes, especially when working at high Xe partial pressure or with enriched 129Xe.
The setup will be totally redesigned/updated in order to
1) increase the overall performance,
2) introduce some new capacities.
- A membrane pump will be used for gas circulation.
- Mass flow controllers will allow us to prepare more easily the three component gas mixtures.
- A solenoid valve controlled by the console of the spectrometer will act as a "stop-flow" that might be synchronized with the NMR pulse sequence.
- Larger and more powerful Helmoltz coils will be used to generate a stronger and more homogeneous polarization field.