Abstract

An electron in front of a metal surface experiences the long-range image force. In the Coulomb-like potential an infinite series of bound hydrogenic states with binding energies E_n ≃ −0.85 eV/n² can exist for many low-index surfaces. These image potential states have been observed by inverse photoelectron spectroscopy and two-photon photoelectron spectroscopy (2PPE) [1]. Their decay is governed by the creation of electron-hole pairs in the metal. Experimental values for the lifetime of the states deduced previously range from ~ 5 fs for the n= 1 state of Fe(110) to ~ 180 fs for the n = 2 state of Ag(100) [1–3].

© 1996 Optical Society of America