The one-dimensional CH3-quantumrotator in solid 4-methyl-pyridine studied by inelastic neutron scattering

Abstract
The phenomenon of tunneling through potential barriers, representing motions which are classically forbidden, has been studied for the case of rotational motion of a methyl group in solid 4‐methyl‐pyridine. A sixfold hindrance potential of 11±3 meV is inferred from a comparison of the directly observed transitions between the three lowest levels and theoretical calculations.