Xenon-129 NMR of silver-exchanged X- and Y-type zeolites

Applications of highly spin-polarized xenon in NMR

“…Xenon adsorbed in NaY with small platinum particles in the pores shows a much larger interaction [35] due to the Knight shift on the metal surface in agreement with the large shifts of small molecules on metal surfaces studied by Stichter and co-workers [36]. The only other zeolite point in figure 1.1 is the anomalous silver-Y zeolite system (AgY) that is the only system showing magnetic shielding greater than the pure gas [37].…”

Characterization of Zeolites — Infrared and Nuclear Magnetic Resonance Spectroscopy and X-Ray Diffraction

“…According to Gedeon et al [402], xenon atoms adsorbed on dehydrated zeolites Cu Yare characterized by chemical shift curves which are displaced to lower 129Xe NMR shift values running almost parallel to each other and to the NaY curve. To date, only dehydrated silver-and copperexchanged zeolites X and Y [391,[403][404][405][406][407] have shown negative or, at least, lower 129Xe NMR shift values than those of xenon atoms adsorbed on zeolites NaX or NaY. In Cu Y zeolites this negative 129Xe NMR shift is due to a specific interaction of xenon atoms with the copper ions via a 3dlO-5do electron donation mechanism from Cu+ to Xe [391,402,406].…”

Optical pumping and xenon NMR

“…Torrey [44] showed that Hunt and Carr's relaxation data were consistent with the spin-rotation interaction where the nuclear spin couples to the angular momentum of the short-lived molecular complex, allowing the xenon to relax much faster than would be expected if dipoledipole interactions were the domir_ant relaxation mechanism. Later work by Shizgal [45], using a 12) potential, improved on the work by Adrian and obtained a 129Xe relaxation time within 40% of the experimental result. The spinrotation interaction is also important in rubidium spin relaxation in optical pumping studies [28] and in the relaxation of spherical top molecules such as CF4 and SFs [46] ., (although in the spherical tops the relaxation is due to an intramolecular coupling).…”

“…The diamagnetic term has been calculated for isolated atoms [8,9] and for xenon, it is about 5600 ppm to lower frequency relative to the bare nucleus. In xenon itself [12]! Calculations of the paramagnetic shifts are more difficult, especially those involving molecular bonds where two-centered (or more) interactions must be "…”