Note on Volt-Dependent Poisoning Effects in Oxide-Cathode Valves

The high vacuum oxide-cathode valve may show cathode poisoning effects when its electrodes are bombarded by electrons of certain discrete energies. Hamaker, Bruining and Aten describe one such effect occurring at about 10 ev. The author confirms this result and describes two other effects occurring at 5.56 ev. and 15.9 ev. The energies of the three effects can be closely associated with the heats of formation of the chlorides, monoxides and sulphates of barium and strontium. It is concluded that the 5.56 ev. effect is due to bombardment dissociation of the monoxides of barium or strontium, the 10 ev. effect to the chlorides and the 15.9 ev. effect either to the sulphates or to a gaseous ionization phenomenon.