The electrical conductivity of thin metallic films II— caesium and potassium on pyrex glass surfaces

An account of an investigation of the electrical conductivity of thin films of rubidium deposited in high vacua on very clean glass surfaces has been previously published. It will be referred to in what follows as Part I. The method has now been used in a similar investigation using caesium and potassium. The vigorous heat treatment of the surface and vacuum technique described in Part I has again been found necessary in order to attain reproducible results, and the effects on contaminated surfaces are similar. It will be seen that the resistivities of the stable films are consistent with the theory given in Part I; moreover, the greater stability of the caesium films has supplied a test of the theory down to thicknesses of only a few A. The decay phenomena associated with the unstable films show a marked gradation through these three alkali metals, the stability of a given film increasing in the order potassium—rubidium—caesium.