Results of an ac heat-capacity study of layering, melting, and layer-critical-point transitions of multilayer ${\mathrm{C}}_2$${\mathrm{D}}_4$ on graphite are reported. The layer critical temperature is found to decrease towards the bulk triple melting point with increasing film thickness. The wetting transition also appeared to be pinned at the triple point. The layer-critical-point transition of a film between one and two layers is found to be 2D Ising type.

• Received 23 May 1986

DOI:https://doi.org/10.1103/PhysRevLett.57.1456