Steady-State Nuclear Double-Resonance Detection of Electric Quadrupole Moment ofK40

Several resonances associated with the ${\mathrm{K}}^{40}$ pure electric quadrupole interaction in KCl${\mathrm{O}}_3$ have been detected which allow the determination of the ${\mathrm{K}}^{40}$-${\mathrm{K}}^{39}$ electric quadrupole moment ratio $\frac{Q_{40}}{Q_{39}}(1.244\mathrm{}\pm 0.002)$ and the asymmetry parameter $\eta (0.621\mathrm{}\pm 0.004)$. These resonances were detected with a new steady-state double-resonance technique which has excellent stability and high sensitivity.