AVS 47th International Symposium
    Surface Science Tuesday Sessions
       Session SS3+MC-TuM

Paper SS3+MC-TuM7
Momentum Space Line Narrowing by Angle Resolved Auger-photoelectron Coincidence Spectroscopy

Tuesday, October 3, 2000, 10:20 am, Room 210

Session: Technique Innovations: Experiment, Theory and Simulation
Presenter: R.A. Bartynski, Rutgers University
Authors: A. Danese, Rutgers University
R.A. Bartynski, Rutgers University
R. Gotter, Lab. Nazionale TASC-INFM, Trieste, Italy
S. Iacobucci, CNR-IMAI Montelibretti, Italy
G. Stefani, U. di Roma III, Italy
Correspondent: Click to Email
We have measured the Ag N@sub 23@VV Auger electron diffraction pattern from the Ag(100) surface in coincidence with Ag 4p photoelectrons under high energy and angular resolution conditions. Measurements were performed using the ALOISA beamline at the ELETTRA synchrotron in Trieste. It is well known that the Auger and photoemission spectra associated with the shallow 4p (3p) core levels of the late 4d (3d) transition metals are unusually broad in energy owing to the rapid decay of the core hole. Furthermore, it has been shown for the Cu 3p and Ag 4p levels that this energy broadening can be eliminated in Auger-photoelectron coincidence (APEC) energy distribution curves. However, this lifetime broadening is expected to generate a concomitant momentum broadening and the resultant Auger diffraction pattern has only a very weak intensity modulation of ~15%. By performing an APEC measurement with high energy and angular resolution, this momentum broadening should be eliminated. In our APEC angular distribution curves, intensity modulations are enhanced to ~50%, consistent with a significant reduction of the momentum uncertainty of the outgoing Auger electrons. These results provide direct evidence that the photoexcitation/Auger decay of these levels is a coherent process. The implications of these results in the context of Auger electron diffraction will be discussed.@footnote 1@ @FootnoteText@ @footnote 1@ Supported by NSF grant NSF-DMR9801681 and NATO grant CRG97-0175.