The nature of an absorbed layer is discussed in terms of quantum mechanics, and the factors governing the sign and magnitude of the electrical double-layer are determined. Although the ionization potentials of Ca, Sr and Ba are greater than the electronic work function of tungsten, a sparse distribution of these atoms on a tungsten surface behaves in a way quite similar to atoms of alkali metals whose ionization potentials are much smaller. This behavior can be understood only in terms of quantum mechanics.

• Received 10 December 1934

DOI:https://doi.org/10.1103/PhysRev.47.479