Isotope shift of nuclear magnetic resonances in 129Xe and 131Xe caused by spin-exchange pumping by alkali metal atoms

The effect of isotope shifts of nuclear magnetic resonance (NMR) frequency in xenon isotopes 129Xe and 131Xe polarized by optically-oriented alkali metal atoms is not only of fundamental interest, but also of practical significance since it is the main factor limiting the accuracy of a whole class of prospective navigation and metrological devices. We have studied the parametric dependences of the isotope shift and have shown that this effect is largely due to incomplete averaging of a inhomogeneous local magnetic field by two xenon isotopes. A numerical model has been derived, which qualitatively describes the effect of isotope frequency shift and provides a good quantitative agreement with the experiment.