The work functions of copper, silver and aluminium

The work functions of surfaces of copper, silver and aluminium, produced by the deposition of thin films of the metal from the vapour on to previously well-aged tungsten surfaces, have been found to be: 4·61 ± 0·04, 4·35 ± 0·05 and 4·25 ± 0·05 eV respectively. These values are based on measurements of the contact difference of potential, between these metals and tungsten, which have been made by the retarding potential method. The conditions which have to be satisfied if reliable results are to be obtained with this method are discussed and the construction of an efficient low-velocity electron gun is described.