ANISOTROPIC INTERMOLECULAR POTENTIAL FROM NUCLEAR-SPIN-LATTICE RELAXATION IN HEXAFLUORIDE GASES

The data on fluorine spin-lattice relaxation times per unit density T- 1/rho in pure SF6 and UF6 gases can be analyzed to obtain information on the anisotropic part of the intermolecular potential in these syste ms. A new and more performant potential, Morse-Morse-Spline-van der Wa als potential (J. Chem. Phys. 94, 1034 (1991)) was used for the isotro pic part of the intermolecular interaction. The analysis was made usin g the Bloom-Oppenheim theory, assuming that the correlation time of th e spin-rotation interaction can be approximated by the average lifetim e of a molecule in a given J 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 an d UF6 were also obtained, being in good agreement with the values repo rted earlier, based on other potentials and techniques.