External Photoelectric Emission of Barium Oxide

Abstract

The spectral distribution of photoelectric yield and its temperature dependency were measured on the barium oxide, in the form of a sprayed coaling on a nickel base. When sample was held at room temperature, the photoelectric emission showed an enhanced effect, that is, the photo-current from the irradiated sample increased with time. The photon energy giving the maximum enhanced effect lies at 2.3ev coincident with the peak of optical absorption by colour centers in barium oxide. This enhanced effect disappeared by warming the sample to 400°K. The results are discussed in terms of an energy level structure of barium oxide.