DYNAMICS OF GUANOSINE SELF-ASSEMBLED AGGREGATES IN THE HEXAGONAL COLUMNAR PHASE BY QUASI-ELASTIC NEUTRON-SCATTERING

Guanosine, one component of the nucleic acids, presents a simple model system to study the self-assembling process and the properties of col umnar liquid-crystalline phases. In a recent x-ray study we investigat ed the structure of the aggregates at medium concentrations and explor ed the phase-diagram as a function of salt concentration in the soluti on. A microscopic model has been presented describing the size and dis tribution of the rod-shaped aggregates consisting of stacked guanosine tetramers. Here we present a first study of the dynamics of guanosine in the two-dimensional hexagonal phase. Inelastic neutron scattering gives further evidence for the ''persistent-flexible-hard-rod'' model; displacements in the hexagonal plane are found to be extremely high. To a detection limit of 0.04 meV we find no evidence for propagating p honon modes. The quasielastic signal measured is attributed to relaxat ional motions that is extremely overdamped motions of the guanosine ro ds.