Ionization of surface-state electrons by microwave fields: Quantum treatment

Abstract
We calculated quantum mechanically the response of surface-state electrons to an applied microwave field. By solving an effective Schrödinger equation which takes into account both bound-bound and bound-continuum transitions to all orders, we show that the ionization proceeds via direct coupling to the continuum. This contrasts with the classical description, where ionization occurs as the result of a diffusive energy gain.