An ac heat-capacity study of C${\mathrm{F}}_4$ on graphite in the multilayer region is reported. The results indicate that C${\mathrm{F}}_4$ does not wet graphite between 18 and 80 K. Below 72 K, the thickness of the adsorbed film is limited to two layers. A bilayer-to-trilayer layering transition is observed near 72 K. The heat-capacity signal shows unusual behavior near $T_{\alpha \beta }$ which may be related to the surface transition in the C${\mathrm{F}}_4$ bulk clusters due to the presence of the graphite substrate.

• Received 28 February 1986

DOI:https://doi.org/10.1103/PhysRevB.34.2056