Number 209 (Story #3), January 8, 1995 by Phillip F. Schewe and Ben Stein HELIUM DOES NOT FLOW WELL ON CESIUM . Above a temperature of 2 K, thin films of helium-4 on a cesium surface can become thick films in a process called wetting. Below 2 K, however, the cesium only allows thin films (only a few atomic layers at most) of He-4 to form, and this, according to James Rutledge of the University of California at Irvine, is not enough for the helium to flow as a superfluid (Physics World, December 1994). In a recent experiment researchers at the University of Exeter in Britain have measured the flow of helium across cesium to be a factor of 10**9 less than the flow of helium across glass. Furthermore, at a temperature of 0.12 K, there was an average of less than 4 x 10**-6 monolayers of helium on the Cs surface. This property may make cesium a good coating for surfaces where the presence of superfluid helium is undesirable. (P. Stefanyi et al., Physical Review Letters, 1 August 1994.)