TRIPLE POINT DEWETTING TRANSITIONS OF HELIUM MIXTURES ON CESIUM

The adsorption of He-3-He-4 mixtures on a cesium substrate has been me asured near bulk liquid phase separation. A first order wetting transi tion is found on the bulk three phase coexistence line at T-w. congrue nt to 0.53 K. The He-3 rich liquid phase wets the surface below T-w, a nd layered films of He-4 rich Liquid under a He-3 rich layer wet the s ubstrate above T-w. The surface phase transition line associated with this wetting transition is found to extend to both sides of the bulk c oexistence line. On the 4He rich side it becomes a line of triple poin t induced dewetting transitions.