Nonwetting of Cesium by Neon near Its Critical Point

We report quartz crystal microbalance measurements of the adsorption of neon on surfaces of cesium and rubidium at temperatures up to the critical point of neon. In the case of Ne/Rb there is little adsorption until the temperature approaches 0.97 of $T_c$, where a wetting transition occurs. In the case of Ne/Cs no adsorption is seen all the way to ${T=T}_c$. Instead our data suggest the presence of a vapor film adjacent to the Cs surface when the sample cell is filled with liquid. This may indicate a crossover from wetting to drying.