Angle-resolved photoelectron spectroscopy coupled with the polarized continuum of synchrotron radiation has been used to identify unambiguously a large enhancement in the photoexcitation from A(100) due to the surface photoeffect. This large enhancement in the cross section occurs only when the excitation field has a component perpendicular to the surface and is due to the dielectric response in the surface region, i.e., to the spatially varying electromagnetic field at the metal surface. An absolute determination of the differential photoionization cross section for excitation of Fermi-energy electrons shows quantitative agreement with Feibelman's self-consistent calculation. A simple picture of the surface photoeffect will be presented.

• Received 22 December 1980

DOI:https://doi.org/10.1103/PhysRevB.24.628