Anomalous behaviour of pentane adsorbed at the graphite/liquid interface

Calorimetry and neutron diffraction have been used to identify and characterise the formation of a solid monolayer of pentane adsorbed on graphite and coexisting with liquid pentane. The observed behaviour is quite different from other alkanes in that the monolayer does not melt above the melting temperature of the pure pentane but at a temperature very similar to that of the bulk material. The lower melting point of the bulk pentane in the pentane/graphite system, when it is present in a relatively small amount, allows the melting point of the solid monolayer to be clearly resolved.