Effect of Oxygen Upon the Photoelectric Thresholds of Metals

Abstract

When a small amount of oxygen is allowed to react with an active surface of certain metals such as thorium, uranium, calcium, barium and caesium the photoelectric threshold is shifted toward the longer wave-length. A similar reaction of oxygen with other metals such as titanium, zirconium, silver, iron, nickel, etc., shifts the threshold toward shorter wave-length, while oxygen produces no effect on gold. The photoelectric work functions for the oxygen treated surfaces of thorium, uranium and calcium obtained agree with the thermionic work functions of tungsten filaments containing oxides of these metals when activated. The experimental results indicate that the effects from these oxygen treated surfaces are due to the activity of the product of the interaction of oxygen with the metal and not due to a single atom layer of the metal on a base material.