Development of a UHV-compatible Low-energy Electron Gun using the Photoelectric Effect

We developed a low-energy (  100 eV) electron gun that uses the photoelectric eŠect, and demonstrated its capability for the study of electronic excitation processes at the surfaces of solids. A LaB 6 (100) single crystal was used as a photocathode and a laser diode ( E photon ＝ 2.62 eV) was used as a light source. The electron gun was compatible with ultra-high vacuum (UHV) con-ditions due to its low outgassing. An energy width of 0.11 eV was obtained without an energy selector, and the maximum current was 38 nA. The energy width of the emitted electrons and the work function of the photocathode were estimated from the relation between the photoelectron energy distribution and the cathode temperature. Using the electron gun, we successfully observed the electron-stimulated desorption of metastable Ne atoms from a solid Ne