| The chemical potential of a meniscus on an inclined, flat plate is a function of its temperature, curvature, film thickness, and height above a reference level. The meniscus thickness profile, which is related to the effective pressure in the liquid, was used as a probe for understanding, demonstrating, and evaluating the sensitivity of the meniscus to the non-equilibrium effects associated with evaporation/condensation mechanisms.;Profiles of draining liquid films (Alkanes) on an inclined, flat, Silicon plate immersed in a pool of liquid were measured as the meniscus formed and reached a steady state. The drainage rate in the ultra-thin film region was significantly different from that due to gravity and was found to depend strongly on temperature fluctuations.;The near-equilibrium thickness profiles of an extended meniscus in the contact line region (width ;The film thickness profile was found to change dramatically when the substrate was heated at the upper end. Consistent with theoretical models, the curvature increased very rapidly from a value of zero in the adsorbed film to a high value and then decreased rapidly till a thickness of about 1 micron. At a high power input, the meniscus was found to oscillate. These results demonstrate the capability of microcomputer enhanced video microscopy for determining and analyzing both the steady state and transient profiles of evaporating thin films. |
