Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A Rollin film, named after Bernard V. Rollin, is a 30 nm-thick liquid film of helium in the helium II state. It exhibits a "creeping" effect in response to surfaces extending past the film''s level (propagation). Helium II can escape from any non-closed surface via creeping toward and eventual evaporation from capillaries of 10 7 to 10 8 meters or greater. Rollin films are involved in the fountain effect where superfluid helium leaks out of a container in a fountain-like manner. They have high thermal conductivity. If not for its evaporation in the presence of heat, a Rollin film would have a very low index of refraction and would be nearly transparent (helium I has an index of refraction of 1.026). The ability of superfluid liquids to cross obstacles that lie at a higher level is often referred to as the Onnes-Effect, named after Heike Kamerlingh Onnes.The Onnes-Effect is enabled by the capillary forces dominating the gravity- and viscous forces.
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