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 (wave propagation). Helium II can escape from any non-closed container via creeping toward and eventually evaporating 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.
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.
Waves propagating across a Rollin film are governed by the same equation as gravity waves in shallow water, but rather than gravity, the restoring force is the Van der Waals force. These waves are known as third sound.
Famous quotes containing the words rollin and/or film:
“Biological possibility and desire are not the same as biological need. Women have childbearing equipment. For them to choose not to use the equipment is no more blocking what is instinctive than it is for a man who, muscles or no, chooses not to be a weightlifter.”
—Betty Rollin (b. 1936)
“This film is apparently meaningless, but if it has any meaning it is doubtless objectionable.”
—British Board Of Film Censors. Quoted in Halliwell’s Filmgoer’s Companion (1984)