Thermal conductance and wettability of xenon on resorcinol-formaldehyde aerogels - art. no. 011404

We have performed thermal conductivity and adsorption isotherm measurements to investigate the system formed by Xe adsorbed on resorcinol-formaldehyde (RF) aerogel. Below 80 K, the thermal conductivity of the Xe/RF-aerogel sy stem is essentially identical to that of the bare RF aerogel; however, abov e this temperature the thermal conductivity of the system increases signifi cantly above that of the bare aerogel. Adsorption isotherm measurements ind icate that Xe incompletely wets the RF aerogel below Xe's bulk triple point temperature. The thickness of the Xe film that forms on the RF aerogel dec reases with decreasing temperature. By 80 K the total amount of Xe present on the aerogel in equilibrium with the saturated vapor pressure is less tha n the amount needed to form about 1.5 atomic layers of Xe on the substrate. We attribute the observed changes in the thermal conductivity of the Xe/ae rogel system to changes in the wettability of the aerogel by the Xe film.