title: Time-resolved investigation of coherently controlled electric currents at a metal surface.
abstract: Studies of current dynamics in solids have been hindered by insufficiently brief trigger signals and electronic detection speeds. By combining a coherent control scheme with photoelectron spectroscopy, we generated and detected lateral electron currents at a metal surface on a femtosecond time scale with a contact-free experimental setup. We used coherent optical excitation at the light frequencies omega(a) and omega(a)/2 to induce the current, whose direction was controlled by the relative phase between the phase-locked laser excitation pulses. Time- and angle-resolved photoelectron spectroscopy afforded a direct image of the momentum distribution of the excited electrons as a function of time. For the first (n = 1) image-potential state of Cu(100), we found a decay time of 10 femtoseconds, attributable to electron scattering with steps and surface defects.
authors.affiliation: Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität, Renthof 5, D-35032 Marburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Güdde
authors.forename: M
authors.initials: M
authors.lastname: Rohleder
authors.forename: T
authors.initials: T
authors.lastname: Meier
authors.forename: S W
authors.initials: SW
authors.lastname: Koch
authors.forename: U
authors.initials: U
authors.lastname: Höfer