Precision measurements of the nuclear magnetic dipole moments of6Li,7Li,23Na,39K and41K

Using the atomic beam magnetic resonance method and using the technique of separated oscillatory fields in combination with the triple resonance method the ratiosg _I /g _J of the stable alkali isotopes Li, Na and K in the²S_1/2-ground state have been measured at magnetic fields of about 3 kOe. Frequency shifts analogous to the Bloch-Siegert-shift, expected from theory, were observed and eliminated by extrapolation to vanishing rf-field strength. The results, uncorrected for atomic diamagnetism, are:⁶Li:g _I /g _J =?0.22356978(10)·10^{?3 7}Li:g _I /g _J =?0.59042719(10)·10^{?3 23}Na:g _I /g _J =?0.40184406(40)·10^{?3 39}K:g _I /g _J =?0.07088613 (6)·10^{?3 41}K:g _I /g _J =?0.03890837 (4)·10^?3 Furthermore, the hyperfine structure splitting constants in the² S _1/2-ground states have been determined. Using the most precise absoluteg _J -values available so far one can calculate absolute values for the uncorrectedg _I - factors. The results are:Δν/MHz ?g _I·10^{3 6}Li: 228.2052590(30) 0.4476540 (3)⁷Li: 803.5040866(10) 1.1822130 (6)²³Na: 1771.6261288(10) 0.8046108 (8)³⁹K: 461.7197202(14) 0.14193489(12)⁴¹K: 254.0138720(20) 0.07790600 (8) By comparing the absoluteg _I - factors with measurements received by the NMR-method, the chemical shifts of the NMR-frequencies caused by the hydrate surrounding of the alkali ions in the NMR-probe are determined.