PHASE-SEPARATION, DENSITY FLUCTUATION, AND CRITICAL-DYNAMICS OF N2 IN AEROGEL

Light scattering was used to study N2 confined in aerogel. We find evidence of liquid-vapor phase separation that terminates at a critical point. Whereas the width of the coexistence curves is substantially reduced relative to bulk N2, the shape of the coexistence curve is similar to that found for the bulk. Photon correlation spectroscopy shows that the density fluctuations decay algebraically in time, a result consistent with the random-field Ising model.