Picosecond field-assisted photoemission from yttrium microstructures

We report the in situ formation of nearly periodic microstructures of different grain size by a 266-nm, 10-psec, 10-Hz laser beam with different energies. Photoelectric emission from these surfaces exhibits enhancement of photoelectric quantum efficiency caused by the changes in the work function and optical absorption. Because of the microstructures, the surface field is also enhanced over the applied field, leading to field-assisted photoemission. For the voltages applied in these experiments, the electron yield increases nearly linearly with the applied field, owing to the Schottky effect. A least-squares fit of the data to the theoretical expression for emission under the Schottky effect yields surface field enhancements of 8--15 over the applied field. copyright 1991 Optical Society of America