Nuclear Spin-Lattice Relaxation in Liquid Nontransition Metals

We develop a broad interpretation for nuclear spin-lattice relaxation in liquid nontransition metals using our new data for Bi²⁰⁹ and previously reported data for Ga69,71, Rb85,87, Sb121,123, Na²³, and In¹¹⁵. Our work provides new insight into the relative importance of the various contributions to the NMR shift K and the nuclear spin-lattice relaxation rate R₁. The three potentially significant contributions to K are the hyperfine contact Kₛ, hyperfine orbital Kₒ, and core polarization Kcp. All other contributions to K are negligible. The sum of Kₒ and Kcp is small compared to Kₛ even in heavy elements. The first significant contribution to R₁ is the hyperfine contact rate R₁ₛ, expressed by the Korringa relation, with K(α), the correction factor for electron-electron interactions, having a reasonable value of about 0.75 for all metals in our study. The second and last non-negligible contribution to R₁ is the nuclear quadrupole rate R1q arising from the effect of ionic motion on the conduction electrons, whose magnitude decreases with an increase in temperature.