Surface intervalley scattering on GaAs(110): Direct observation with picosecond laser photoemission

Angle-resolved laser photoemission investigations of the laser-excited GaAs(110) surface have revealed a previously unobserved valley of the C3 unoccupied surface band whose minimum is at X in the surface Brillouin zone. Electron population in this valley increases only as a result of scattering from the directly photoexcited valley at . With high momentum resolution, we have isolated the dynamic electron population changes at both and X and deduced the scattering time between the two valleys. © 1989 The American Physical Society.