NUCLEAR MAGNETIC AND QUADRUPOLE-RESONANCE STUDY OF MOLECULAR-DYNAMICSIN A MODEL BILAYER COMPOUND C6H13NH3CL

Molecular dynamics in a model bilayer compound C6H13NH3Cl is Studied b y H-1 spin-lattice relaxation in the laboratory and in the dipolar sys tem as; well as by N-14 nuclear quadrupole resonance. In the low tempe rature monoclinic phase, the NMR data show the presence of a slow moti on which is presumably the 120 degrees reorientation of a C-NH3 group around the C-N bond. In the high temperature tetragonal phase, the nuc lear magnetic and quadrupole resonance data show the presence of two m otions in addition to the reorientation of the C-NH3 groups: a fast mo tion causing a strong temperature variation of the N-14 NQR frequencie s, and a slow motion dominating the proton spin-lattice relaxation in low external magnetic field and in the dipolar system. Various models of molecular dynamics in the high temperature tetragonal phase are exa mined in relation to the experimental data. (C) 1998 American Institut e of Physics.