Quantum yield measurements of photocathodes illuminated by pulsed ultraviolet laser radiation

The electron quantum yields from polycrystalline lanthanum hexaboride and barium irradiated by near ultraviolet laser excitation have been determined. These measurements show that the quantum yields from these materials are dependent on the processing and previous history of the photocathode material. For lanthanum hexaboride, a yield of 7*10/sup -6/ with 337 nm irradiation has been achieved. For barium, a yield of 1*10/sup -6/ has been measured with excitation at 308 nm. These results are discussed and future plans are outlined.<>