Calorimetric investigation of the monolayers formed at solid-liquid interface

Heat capacity measurements have been made to investigate the formation of t wo solid monolayers each of n-pentane, n-heptane and n-dodecane adsorbed on graphite, one at submonolayer coverages and the other coexisting with the liquid. At submonolayer coverages the monolayers are found to melt respecti vely at 99.8, 151.6, and 217.3 K, well below the bulk melting points. The m onolayers coexisting with the liquid melted at 205.6 for heptane and at 287 .8 K for dodecane, whereas no evidence was obtained for pentane on the form ation of such solid monolayer above the bulk melting point. The order persi sting in the liquid near the interface depends upon the length of the molec ules. The dodecane monolayers showed another transitions below the melting points both at submonolayer and multilayer coverages.