Adsorption of Thin Liquid Helium Films on Cs Measured via Photoelectron Tunneling

Abstract

The alkali metals Cs and Rb are the only surfaces which are not wetted by superfluid 4He below a certain temperature. In our experiments, using the photoelectron tunneling method, we can highly resolve the growth of the non-wetting thin-film state of 4He on a quench-condensed Cs surface. It turns out that far from coexistence there is little adsorption of helium. In contrast, close to coexistence a rapid growth up to two monolayers of helium is observed, but the surface is still non-wet under the usual convention.