Triple-point wetting of argon and methane on gold

We have performed high sensitivity quartz microbalance measurements of argon and methane adsorbed on gold. On smooth and flat gold electrodes we have found that both of these systems undergo the common triple-point wetting. Vice versa, on some heterogeneous gold electrodes the temperature scans of argon along the solid-vapor coexistence line show pronounced hysteresis loops between cooling and heating, while those of methane were, within the experimental resolution, reproducible.