Aging dynamics in a colloidal glass - art. no. 021510

The aging dynamics of colloidal suspensions of Laponite, a synthetic clay, is investigated using dynamic light scattering (DLS) and viscometry after a quench into the glassy phase. DLS allows to follow the diffusion of Laponi te particles and reveals that there are two modes of relaxation. The fast m ode corresponds to a rapid diffusion of particles within "cages" formed by the neighboring particles. The slow mode corresponds to escape from the cag es: its average relaxation time increases exponentially fast with the age o f the glass. In addition, the slow mode has a broad distribution of relaxat ion times, its distribution becoming larger as the system ages. Measuring t he concomitant increase of viscosity as the system ages, we can relate the slowing down of the particle dynamics to the viscosity.