Magnetic resonance of He-3 and Xe-129 in aqueous solutions containing paramagnetic Mn2+ and Co2+ ions. A comparison with isoelectronic Li-7(+) and Cs-133(+) ions

The chemical shifts and relaxation times T-1 and T-2 of He-3 and Xe-129 nuc lei of noble gas atoms as well as those of Li-7 and Cs-133 nuclei of isoele ctronic Li+ and Cs+ ions have been measured in aqueous solutions, which con tain paramagnetic Mn2+ and Co2+ ions. The magnetic relaxation of all studie d nuclei in Co2+ solutions proceeds via an electronic spin relaxation of th ese ions. The relaxation in Mn2+ solutions is determined by the translation al diffusion of the solute particles. The closest approach distances for co llisions of paramagnetic ions with atoms of noble gases and alkali ions wer e estimated from relaxation data.