Wetting near triple points

The quartz microbalance technique has been used to study the coverage of argon and methane films in the vicinity of the bulk triple point. In contrast to previous measurements, close to the triple point, the discontinuities in the coverage indicate first-order surface phase transitions. A thermodynamic model shows that argon forms a layered solid-liquid film in a range around the triple point, but is liquid both above and below this range. Methane films make a transition directly from solid to liquid. These observations are examples of the rich phase behavior near bulk triple points predicted by Pandit and Fisher [Phys Rev. Lett. 51, 772 (1983)].