Anisotropic intermolecular potential from nuclear spin-lattice relaxation in hexafluoride gases

The data on fluorine spin-lattice relaxation times per unit densityT _jσ in pure SF₆ and UF₆ gases can be analyzed to obtain information on the anisotropic part of the intermolecular potential in these systems. A new and more performant potential, Morse-Morse-Spline-van der Waals potential (J. Chem. Phys.94, 1034 (1991)) was used for the isotropic part of the intermolecular interaction. The analysis was made using the Bloom-Oppenheim theory, assuming, that the correlation time of the spin-rotation interaction can be approximated by the average lifetime of a molecule in a givenJ state. We have obtained the strengths of the repulsive and attractive terms in the anisotropic potential. From the strength of the attractive term, the hexadecapole moment of SF6 and UF6 were also obtained, being in good agreement with the values reported earlier, based on other potentials and techniques.