Deuteron and carbon magnetic resonance studies of supercooled liquid and glassy salol

The glass-former salol was studied using carbon and deuteron NMR. For the C-13 measurements protonated samples were used. For the deuteron experiments salol was selectively deuterated at the phenyl ring. The measurement of the spin-lattice relaxation times provides clear evidence for an anisotropic reorientation of the molecules in the supercooled liquid. Close to the glass transition a bimodal longitudinal magnetization recovery is observed which indicates the presence of relatively slow intramolecular degrees of freedom. From deuteron solid echo spectra this process is identified as a uniaxial large amplitude motion of the phenyl group which exhibits a broad distribution of correlation times. (C) 2000 American Institute of Physics. [S0021-9606(00)51213-6].