A first order two-dimensional melting transition : methane adsorbed on (0001) graphite

Abstract
The variation of long range order of a registered solid submonolayer of methane adsorbed on the graphite basal plane is measured at melting by neutron elastic scattering. The sudden loss of order indicates a first order melting transition and defines the two-dimensional triple point of the layer, namely 56 ± 0.4 K