Electron dynamics at semiconductor surfaces and interfaces

The application of femtosecond laser photoemission to the study of electron dynamics at semiconductor surfaces and interfaces is described. Fundamental processes such as electron-electron and electron-phonon scattering, diffusion and recombination are discussed. The dynamical evolution of photoexcited electrons on the As/Ge(111) surface is studied with broadly tunable harmonics. Extension of high harmonic generation to produce photon energies approaching 80 eV have resulted in the first atomic core level photoemission spectra from a tunable femtosecond source. Possible applications of harmonics to studies of surface photochemistry are discussed.