Photoemission with picosecond lasers: fast electron dynamics at the GaAs [110] surface

Subpicosecond pulses of 10.7-eV radiation from a tunable laser-based source are used to carry out photoemission investigations of the electronic dynamics on the laser-excited surface of GaAs [110]. Angle-resolved studies have revealed a rapid surface intervalley scattering process that transfers electrons between the directly excited, surface Brillouin zone center to a previously unobserved valley within the bandgap at the surface zone edge. The scattering time has been determined to be 0.4+or-0.1 ps. A model that describes the scattering dynamics is presented.>