Wetting studies of liquid 4He on various Cs surfaces

Cesium is a surface not wetted by liquid 4He below a certain temperature, Tw=2K. However, one observes that a thick helium film remains on the Cs substrate even if the surface is cooled below Tw from the wetted state. This leaves the question how the system will finally evolve from this metastable state to the thermodynamic equilibrium, represented by a microscopically thin film. We investigate the dynamic and static behaviour of dewetting 4He films on cesiated surfaces. Space and time resolved measurements of the thickness of the helium film are performed using a surface plasmon microscope. We have measured the work function of pure and oxidized Cs via photo current spectroscopy