Untersuchungen über die magnetische Kernresonanz von Alkalikernen in wäßriger Lösung

Abstract

The NMR signals of the nuclei 2H, 6Li, 7Li, 23Na, 87Rb and 133Cs have been investigated in aqueous solutions. The ratios of the Larmor-frequencies of these alkali nuclei relative to 2H have been measured with high accuracy. Because the Larmor-frequencies depend on the concentration of the aqueous solutions, an extrapolatiton to vanishing concentration was made. From these ratios of Larmor-frequencies, a magnetic moment for the alkali nuclei has been derived and has been compared with the available nuclear magnetic moments from atomic beam or optical pumping experiments. The difference in the magnetic moments results from the shielding of the alkali nuclei by the water molecules around the ions. The shielding constants are: σ (Rb+) = — (2.0 ± 0.2) ·10-4 and σ (Cs+) = — (3.4 ± 0.1) · 10-4 relative to the free ion. The shift of the 133Cs NMR line as a function of the concentration of aqueous solutions of Cssalts is given in detail. The influence of the chlorides of some elements in the iron group and of some lanthanide elements on the position of the 133Cs NMR line is shown.