Prewetting Transitions in a Near-Critical Metallic Vapor

Velocity of sound measurements at 10 MHz in near-critical liquid and vapor mercury up to supercritical temperatures and pressures of 1900 K and 1800 bars, respectively, demonstrate the existence of a wetting transition on the walls of molybdenum and niobium cells at TW1250K, together with an associated first-order prewetting line in the dense mercury vapor that terminates at a prewetting critical point (Tc,pre,pc,pre)(1860K,0ex0ex1830bars) lying above the bulk mercury critical point at (Tc,pc)0ex0ex=0ex0ex(1764K,0ex0ex1670bars).