Study of Thermal Mobility by Means of 1H NMR Magic-Angle Spinning Sideband Analysis

1H nuclear magnetic resonance (NMR) magic-angle spinning (MAS) sideband patterns of molecules adsorbed in zeolites or related materials both depend on the MAS frequency and the thermal mobility. By using a statistical NMR line shape theory a valuable information on the thermal motion can be derived from the MAS sidebands. The conclusions are compared with the results of longitudinal proton spin relaxation studies at different temperatures and Larmor frequencies. The measurements are performed on samples of ethylene glycol molecules adsorbed in zeolites of the NaX and sodalite type which were prepared under well-defined conditions in vacuum. It is shown that the comparison of the respective results is very suitable for a deeper understanding of the dynamics of the adsorbed molecules.