In situ neutron powder-diffraction was used to probe the Ne content and diffusion kinetics in C60 by monitoring the C60 lattice parameter versus time following step changes in applied Ne pressure. In the face-centered-cubic phase where the C60 molecules were freely rotating, diffusion was slower for higher Ne pressure. In the primitive cubic phase where the C60 molecules were orientationally ordered, the diffusion rate was slower and was essentially independent of pressure. These observations could be understood in terms of three unequal competing effects: (1) Increasing the external Ne pressure increased the driving force for diffusion; (2) compression of the C60 lattice slows diffusion with increasing pressure; and, the major one, (3) C60 molecular dynamics enables and enhances diffusion by a thermally activated so-called paddle-wheel effect. The activation energy for such Ne intercalated C60 reorientational hopping or rotation (1500K or 13kJ/mole) was less than that in pure C60 (2600K or 22kJ/mol), suggesting that the Ne atoms acted as "roller bearings."Ne Intercalated C60: Diffusion Kinetics. Morosin, B., Hu, Z., Jorgensen, J.D., Short, S., Schirber, J.E., Kwei, G.H.: Physical Review B, 1999, 59[9], 6051-7