ROTATIONAL MOTION IN PLASTIC QUINUCLIDINE - RESULTS FROM QUASI-ELASTIC NEUTRON-SCATTERING

Results of incoherent quasielastic neutron scattering experiments on quinuclidine, C//7 H//1//3 N, in its plastic phase (room temperature) are presented. The observed quasielastic spectra are compared to several models for the rotational motion of the molecules. It is found that the data support a picture, where the molecules perform 90 degree -reorientations about crystallographic C//4 -axes with a residence time of (24. 8 plus or minus 2. 5). 10** minus **1 **2 s, and 120 degree -reorientations about the molecular C//3 -axis with a residence time of (9. 6 plus or minus 2. 0). 10** minus **1 **2 s.