Abstract

Angle resolved two-photon photoemission (TPPE) spectroscopy has shown that the energies and effective masses of image potential electrons outside metal surfaces are very sensitive to the morphology and electronic structure of atomically thin adlayers [1]. On a bare metal surface, an excess electron is bound by a Coulomb potential arising from the polarization it induces in the metal surface. As layers of a dielectric material are grown on the surface, the image state binding energies change because the Coulombic interaction is modified by dielectric effects and the electronic structure of the adlayer slab. The effective mass for motion parallel to the surface is influenced by the band structure of the metal and the adlayer potential. Here we show that femtosecond angle-resolved TPPE allows us to study in detail the factors which control the dynamics of electrons at interfaces over the transition from 2-D to 3-D behavior.

© 1996 Optical Society of America