Second virial coefficient of 129Xe chemical shielding in mixtures of Xe with spherical top molecules CH4, CF4, and SiF4

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Abstract
129Xe chemical shifts in mixtures of Xe with CH4, CF4, and SiF4 as a function of temperature and density have been obtained by pulsed Fourier transform NMR spectroscopy. The low densities of gases used and the previously determined 129Xe shifts in pure xenon enable the determination of the chemical shielding contribution which is linear in density for Xe–CH4, Xe–CF4, and Xe–SiF4 molecular pairs, with a high degree of precision. An approximate reduced second virial coefficient of chemical shielding for 129Xe in Xe interacting with other molecules can be defined, which leads to superposition of Xe–Xe and Xe–Kr curves over a large part of the reduced temperature range for which data is available. Estimates of well depths for Xe–Ar, Xe–CH4, Xe–CF4, Xe–SiF4, and Xe–HCl have been obtained by this method.