Rollin film

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Helium II will "creep" along surfaces in order to find its own level - after a short while, the levels in the two containers will equalize. The Rollin film also covers the interior of the larger container; if it were not sealed, the helium II would creep out and escape.

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). This "creeping" seemingly ignores gravity. It 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).

A short explanation for the phenomenon would be that in this state, the temperature of the Helium is so low that almost all Helium atoms are in the lowest (quantum mechanical) energy state. Since energy can only be lost in discrete steps, and atoms in the lowest state cannot lose any energy, gravity and friction have no effect on single atoms.

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