title: Dynamic screening probed by core-resonant double photoemission from surfaces.
abstract: The universal response of a sudden created core hole, predicted to occur on an attosecond (10(-18)  s) time scale, lacks an experimental demonstration. With a two-dimensional coincidence spectrometer, we demonstrate an extensive energy sharing between the Ag 4p photoelectron and the N2,3VV Auger electron exceeding 10 eV. This energy width provides access to the time scale of the emission process. This is the fingerprint of the dynamic fluctuation process 4p(-1)⇌4d(-2)4f. The shakeup induced interband transitions from the Ag(100) surface are also identified by comparing the coincidence spectrum with the M4,5VV Auger transitions.
authors.affiliation: Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany.
authors.forename: Z
authors.initials: Z
authors.lastname: Wei
authors.affiliation: Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany.
authors.forename: F O
authors.initials: FO
authors.lastname: Schumann
authors.affiliation: Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany.
authors.forename: C H
authors.initials: CH
authors.lastname: Li
authors.affiliation: Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Behnke
authors.affiliation: Scuola Dottorale in Matematica e Fisica, Università Roma Tre, via della Vasca Navale 84, 00146 Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Di Filippo
authors.affiliation: CNISM and Dipartimento di Scienze, Università Roma Tre, via della Vasca Navale 84,00146 Rome, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Stefani
authors.affiliation: Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany and Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, 06099 Halle, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Kirschner