Molecular motion in supercooled glycerol

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Abstract
Quasi-elastic Rayleigh scattering of 14·4 keV photons has been measured on supercooled liquid glycerol at -30°C and 0°C by employing the Mössbauer effect. Total scattered intensity, quasi-elastically scattered intensity I q and energy width of I q(k, ω) have been determined for k=0·6 to 4·2 Å-1. The molecular motion is modelled as: random-walk diffusional motions for the centre-of-mass translation and for the orientation of independent rigid molecules, plus fast-bounded translational jitter (vibration). The model parameters are evaluated. The temperature dependence of the translational diffusion constant corresponds to an activation energy of 12 kcal/mol. Comparison is made especially with N.M.R. results for rotational motion. The effect of orientational jitter (libration) is considered and its possible influence on nuclear magnetic relaxation is pointed out.