EXPERIMENTAL-OBSERVATION OF PREWETTING IN A BINARY-LIQUID MIXTURE

We present experimental evidence for the existence of a prewetting tra nsition for the binary liquid mixture of cyclohexane and methanol. For certain compositions in the mixed region of the phase diagram, a firs t-order thin to thick film transition can be observed. The observed tr ansition exhibits a large hysteresis. It is shown that the prewetting line approaches the coexistence curve tangentially. Also, the prewetti ng critical point displays 2-D Ising-like criticality. These findings are compared to recent experiments on other systems, in which prewetti ng was also observed.