Adsorption and structuring phenomena at the solid/liquid interface

Evidence for the presence of structured solid-like layers at interfaces between a graphitised carbon surface and liquid alkanes, alkanols and their mixtures is reviewed. At temperatures close to the m.p. the longer chain compounds (n > 10) from solid-like regions several molecular layers thick which break down as the temperature is raised, reaching monolayer thickness 10-30 K above the m.p. For alkanes, further break-down of this monolayer structure occurs smoothly, but for alkanols a steeper transition is observed over a few degrees. A simple statistical theory gives a satisfactory account of the “melting” of thick layers, but a more detailed theory will be needed to describe the phase transitions in the monolayer region.