CRITICAL-DYNAMICS IN THE PRESENCE OF A SILICA-GEL

Dynamic and static light scattering results are reported for isobutyric acid and water in a 4 wt. % silica network with a crossover length of 300 angstrom. In the one-phase region, well away from the critical point, the decay rate for order parameter fluctuations is unaffected by the network. Near the critical point, the order-parameter correlation function is well fitted by the sum of an exponential with decay rate GAMMA-1 and a term of the form exp[ln(tau/t0)/ln(GAMMA-2t0)]3, with GAMMA-2 congruent-to GAMMA-1. When the system reaches conditions where the correlation length of the pure system is approximately 100 angstrom, it spontaneously orders.