Nuclear Magnetic Resonance ofXe129in Natural Xenon

Nuclear magnetic resonance studies of natural xenon have been continued using fluid samples with improved purity. The ${\mathrm{Xe}}^{129}$ spin-lattice relaxation time in the gas was found to be inversely proportional to the density: $\frac{1}{T_1}=(5.0\mathrm{}\pm 0.5)\times {10}^{-6\mathrm{}} \rho$, where $T_1$ is in sec and $\rho$ in amagats. For the liquid in equilibrium with its vapor, the relaxation time throughout the temperature range 0° to -72°C is 1000±200 sec. In both the gas and the liquid the paramagnetic shift in the resonant value of the local field $H$ at the nucleus, relative to its value for the isolated atom in the same external field, is directly proportional to the density and the external field: $\Delta H=+(4.22\mathrm{}\pm 0.05)\times {10}^{-7\mathrm{}} \rho H_0$, where $\Delta H$ and $H_0$ are in G and $\rho$ is in amagats. The above $T_1$ and $\Delta H$ data agree well with a relationship derived by Torrey involving an analysis of the fluctuating magnetic field at a nucleus due to the rotation of a diatomic configuration. The derivation is based on Ramsey's theory of the chemical shift and the spin-rotational coupling which exist when two atoms are sufficiently close to interact.