By Mark E. Limes
This thesis describes longitudinal nuclear rest measurements of sturdy 129Xe close to seventy seven ok with formerly not possible reproducibility, and demonstrates alterations in leisure, established upon the way the cast is condensed. those effects are at once acceptable to the iteration and garage of enormous amounts of hyperpolarized 129Xe for numerous functions, similar to lung magnetic resonance imaging (MRI). The thesis encompasses a refined theoretical method of those facts units, together with ameliorations to a well-established Raman-phonon scattering idea which can clarify the bigger scatter in and discrepancies with earlier work.
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Extra resources for 129 Xe Relaxation and Rabi Oscillations
4) × 10−8 per amagat. 2) Torrey admits this calculation is probably fortuitous, and if one considers the orderσ av(exp) , the theory leads of-magnitude discrepancy between σ av(Torrey) and to a two-orders-of-magnitude discrepancy in the theoretical T1 compared to the experimental T1 . Hunt and Carr use an experimental value for σav in Torrey’s theory (instead of Torrey’s theoretical σav ) and calculate a longitudinal relaxation time that is slightly greater than twice the experimental value for liquid xenon.
2. At temperatures below 20 K, it is suggested that a cross relaxation with 131 Xe limits the 129 Xe T1 to hundreds of hours at a magnetic field of 1 kG, which is considered due to the incompatibility of the spin-rotation theory in this temperature range. 2 K, there is a magnetic field dependence up to 1 kG. As the magnetic field decreases drastically (less than 15 G), the T1 of 129 Xe decreases and the polarization of the 131 Xe increases, indicative of spin-exchange from 129 Xe to 131 Xe and providing evidence that cross relaxation is a mechanism in effect at these low temperatures (although also at low fields).
Hunt and Carr use an experimental value for σav in Torrey’s theory (instead of Torrey’s theoretical σav ) and calculate a longitudinal relaxation time that is slightly greater than twice the experimental value for liquid xenon. Meanwhile, Yen and Norberg, at Washington University of St. Louis, observe a temperature-dependent chemical shift for solid 129 Xe presented in the first published work that contains solid xenon NMR data . Specifically, they report self-diffusion coefficients, resonance shifts, and transverse (spin-spin, T2 ) relaxation times for a range of pressures (saturated vapor pressures to 20 atm) and temperatures (4–227 K) for naturally abundant xenon in liquid and solid phases.
129 Xe Relaxation and Rabi Oscillations by Mark E. Limes