Electron quantum yields from a barium photocathode illuminated with polarized light

Photoemission measurements with a barium photocathode and a nitrogen laser are reported. The cathode is prepared by evaporating barium onto a copper disc. Radiation from a nitrogen laser (337 nm, 10 ns) is polarized and strikes the cathode surface at variable angles. An electron quantum yield as high as 1×10^-3 is observed. The dependence of the quantum yield on the beam polarization and angle of incidence is investigated. The results indicate that higher quantum yields are achieved when the laser beam is incident at an angle of ~55° and is polarized perpendicular to the plane of incidence