Surface localisation of laser photoelectron emission using Cu2O and Ag film structures

A laser electron source localised on a photocathode surface was developed on the basis of Ag and Cu₂O thin films sequentially deposited by magnetron sputtering on a glass substrate. Photoemission of electrons under the action of the fourth (263 nm) harmonic of a femtosecond fibre laser was initiated from the surface of an Ag film deposited on the substrate surface. Photoelectron source localisation on the photocathode surface was provided by sputtering the Cu₂O copper oxide film on its surface, which significantly (about 50 times) reduced the photoemission efficiency, and by subsequent removal of the copper oxide layer in the photoemission spot with a diameter of ~15 μm by means of focused secondharmonic radiation of a femtosecond fibre laser. In conducting research on the photocathode surface, a grid of photoemission spots was formed, which greatly facilitated the laser beam alignment with the photoemission spot. A decrease in the noises of ultrafast transmission electron microscope, associated with spatial fluctuations of the laser beam initiating pulsed photoelectron emission from the microscope photocathode when using a localised electron source on the basis of a structure of thin Cu₂O and Ag films, was experimentally demonstrated.