Abstract
Total quantum-mechanical scattering cross sections of LiF on Ar, Kr, and N2 were measured as a function of collisional velocity in the thermal energy range, to about 1%–2% accuracy, through the use of circular beam geometry and a McLeod gauge to measure target gas density. Good absolute agreement with the Schiff–Landau–Lifshitz elastic scattering theory and the calculated 1/r6 long-range potential was obtained at only the lowest experimental velocities. At higher velocities the cross section is larger than predicted by this theory. No glory undulations were detected. Forces arising from the higher-order multipoles are insufficient to explain the results, but molecular protrusion correlates with the ordering of the deviations observed.