The Nuclear Spin and Magnetic Moment of Potassium (41)

Abstract

The spin of the ${\mathrm{K}}^{41}$ nucleus and the h.f.s. separation of the ${}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$ normal state have been measured by the method of zero moments. The high resolution necessary to separate the two isotopes was obtained by passing a beam of neutral potassium atoms through a weak inhomogeneous magnetic field 153 cm long. The total beam length was 201 cm. A new method of analysis of the zero moment peak of ${\mathrm{K}}^{41}$ in relation to that of ${\mathrm{K}}^{39}$ was used in the determination of the spin. The spin was found to be 3/2 and the h.f.s. separation to be 0.554±0.2 percent of that of ${\mathrm{K}}^{39}$. The same ratio applies to the magnetic moments, hence this ratio and the values for ${\mathrm{K}}^{39}$ given by Fox and Rabi yield $\left\{\Delta \nu \right({\mathrm{K}}^{41}),=0.00853\mathrm{}\pm 0.0001 {\mathrm{cm}}^{-1\mathrm{}}\}\left\{\mu \right({\mathrm{K}}^{41}),=0.22\mathrm{} \mathrm{nuclear}\mathrm{Bohr}\mathrm{magneton}.\mathrm{}\}$ From the peak intensities it is possible to give the abundance ratio ${\mathrm{K}}^{39}$/${\mathrm{K}}^{41}$ as 13.4±0.5.