Nuclear magnetic shielding of noble gases in an anisotropic environment: 21Ne and 129Xe in a liquid crystal

The effect of long-range attractive van der Waals interactions on the nuclear magnetic shielding of a noble-gas atom in an anisotropic environment is discussed. In addition to the isotropic effect, there exists a term proportional to the anisotropy of the second shielding hyperpolarizability tensor and to the anisotropic part of the mean-square electric field. The developed formalism is applied to explain the medium-induced shieldings of 129Xe and 21Ne in the nematic liquid-crystal EBBA.