Surface intervalley scattering on GaAs(110) studied with picosecond laser photoemission

Laser-based photoemission sources provide the unique opportunity to study dynamic electronic processes at surfaces and interfaces. Using angle-resolved, laser photoemission with < 1 ps time resolution, we have directly observed a new surface band at the X̄ point in the GaAs(110) surface Brillouin zone. The appearance of electron population in this valley occurs only as a result of scattering from the directly photoexcited valley at G{cyrillic}. The momentum resolution of our experiment has permitted us to isolate the dynamic electron population changes at both G{cyrillic} and X̄ and to deduce the scattering time between the two valleys. © 1989.