Abstract

Two-dimensional electronic systems have been the subject of considerable interest for the last few decades. An interesting excited-state two-dimensional electronic system is that of the image-potential states on highly polarizable single-crystal surfaces. Bound states result from an electron confined between the projected band gap of the crystal and the potential of the image charge at the surface—to give a Rydberg series of states with binding energies E_n typically ≲0.8 eV below the vacuum level. Although image states have been extensively studied on various single-crystal metal surfaces in recent years, the scattering mechanism for image-state electrons has not been extensively investigated. Here, we present an angle-resolved two-photon photoemission (2PPE) investigation of the scattering of the n = 1 image-state electrons by ionized species, introduced through Na adsorption at a Cu(111) surface. The use of angle-resolved photoemission allows us to selectively study the electron dynamics as a function of a given, unique lateral velocity.

© 1995 Optical Society of America