Edge Contact Angle, Capillary Condensation, and Meniscus Depinning

We study the phase equilibria of a fluid confined in an open capillary slit formed when wall finite length $H$ is brought distance $L$ away from second macroscopic surface. This system shows rich arising competition between two different types condensation, corner filling and meniscus depinning transitions depending on value aspect ratio $a=L/H$. For long capillaries, with $a<2/\ensuremath{\pi}$, condensation type I involving menisci which are pinned at top edges ends characterized by edge contact angle. intermediate $2/\ensuremath{\pi}<a<1$, angle may be or II, overspill into reservoir there no pinning. short $a>1$, always II. In all regimes, completely suppressed for sufficiently large angles. show that additional continuous transition condensed liquidlike phase, associated each as they round upper slit. Finite-size scaling predictions developed these boundaries connect fluctuation theories wetting transitions. test several our using fully microscopic density functional theory allows us to its suppression molecular level.