Nuclear Magnetic Resonance and Relaxation in Iridium Metal: The Nuclear Magnetic Dipole Moments ofIr191andIr193

Abstract

The nuclear magnetic resonances of ${}_{}{}^{191}{}_{}{}^{}\mathrm{Ir}$ and ${}_{}{}^{193}{}_{}{}^{}\mathrm{Ir}$ have been detected by pulsed NMR techniques in iridium metal in the temperature range $T=1-4\mathrm{}$°K and in external magnetic fields between 50 and 60 kOe. The observed frequency-field ratios for these isotropes are $\frac{{\nu }^{\mathrm{}\left(191\right)\mathrm{}}}{H}=0.074127\mathrm{}\left(18\right)\mathrm{}$ kHz/Oe and $\frac{{\nu }^{\mathrm{}\left(193\right)\mathrm{}}}{H}=0.080725\mathrm{}\left(6\right)\mathrm{}$ kHz/Oe. By combining the measured spin-lattice relaxation times ${T_1}^{\mathrm{}\left(193\right)\mathrm{}}T=2.8\mathrm{}\pm 0.2$ sec °K with known values of the magnetic susceptibility and electronic specific heat, the Knight shift in iridium metal is estimated to be $K=+(1.3\mathrm{}\pm 0.4)\%$. Applying this shift to the experimental frequency-field ratios yields the nuclear magnetic dipole moments (uncorrected for diamagnetic shifts) ${\mu }^{\mathrm{}\left(191\right)\mathrm{}}=0.1440\mathrm{}\left(6\right)\mathrm{}{\mu }_N$ and ${\mu }^{\mathrm{}\left(193\right)\mathrm{}}=0.1568\mathrm{}\left(6\right)\mathrm{}{\mu }_N$.