Heat Capacity of Krypton Physisorbed on Graphite

The results of an exhaustive high-precision heat-capacity study of the submonolayer regime of the krypton-graphite (Grafoil) adsorption system are presented. A phase diagram exhibiting a single two-phase coexistence region is proposed as an alternative to the previously proposed triple-point phase diagram. A quantitive correspondence between the locus of heat capacity anomalies in the Kr-graphite system and that for the ${\mathrm{N}}_2$-graphite system suggests the proposed phase diagram may apply to the ${\mathrm{N}}_2$ system as well.