Photoelectric Emission from Barium Oxide

Abstract

The photoelectric emission from barium oxide has been investigated by measuring the total photoelectric yield and the distributions in kinetic energy of the emitted electrons using an improved magnetic velocityanalyzer tube. The energy distribution measurements revealed four "fast peaks" which are interpreted as being associated with direct transitions from energy levels located approximately 1.0, 1.4, 2.0, and 2.6 eV below the vacuum level. Confirmation of these transitions was obtained from plots of the spectral distribution of the total photoelectric yield. A "slow peak" was observed in the energy distributions at about 0.5 eV which is attributed to exciton-induced photoelectric emission. Evidence is presented indicating that this is a true peak and not the truncated tail of a distribution which peaks at still lower energies. Possible identifications of the energy levels involved in the direct transitions and the energy loss mechanism involved in the exciton-induced transitions are discussed.