AVS 46th International Symposium
    Surface Science Division Thursday Sessions
       Session SS3+AS+NS-ThM

Paper SS3+AS+NS-ThM2
Demonstration of Angle Resolved Auger-photoelectron Coincidence Spectroscopy from a Solid: First Results from the Cu(111) Surface

Thursday, October 28, 1999, 8:40 am, Room 604

Session: Novel Surface Probes & Technique Enhancement
Presenter: D.A. Arena, Rutgers University
Authors: D.A. Arena, Rutgers University
R.A. Bartynski, Rutgers University
D. Cvetko, Laboratorio Nazionale TASC-INFM, Italy
L. Floreano, Laboratorio Nazionale TASC-INFM, Italy
A. Morgante, Laboratorio Nazionale TASC-INFM, Italy
F. Tommasini, Laboratorio Nazionale TASC-INFM, Italy
A. Attili, Universita' di Roma, Italy
A. Ruocco, Universita' di Roma, Italy
G. Stefani, Universita' di Roma, Italy
L. Marassi, Universita' di Modena, Italy
P. Luches, Universita' di Modena, Italy
S. Iacobucci, CNR-IMAI, Montelibretti, Italy
Correspondent: Click to Email
We report the first successful angle-resolved Auger-photoelectron coincidence spectroscopy (AR-APECS) measurements from a solid. These measurements were made at the ALOISA beamline at the ELETTRA synchrotron radiation center in Trieste, Italy. This novel analysis chamber is equipped with seven hemispherical electron energy analyzers mounted on two independent rotatable frames; the arrangement allows for the efficient exploration of different kinematical conditions for the emitted pair of electrons. We measured the angular distribution of Cu L@sub3@VV Auger electrons from the Cu(111) surface in coincidence with Cu 2p@sub 3/2@ photoelectrons emitted at selected angles; these angles correspond to maxima and minima in the photoelectron diffraction (PED) pattern. When the 2p@sub 3/2@ core level is at a PED maximum, the Auger pattern is indistinguishable (within statistics) from the noncoincidence distribution. In contrast, if the 2p@sub 3/2@ photoelectrons are at a PED minimum, the coincidence Auger angular distribution shows additional structure as compared to the noncoincidence pattern. This observation may arise because the two coincidence conditions access different intermediate states. The effects of the lattice may be more pronounced in the Auger angular pattern collected in coincidence with photoelectrons on the PED maximum while the Auger angular distribution acquired in coincidence with the photoelectrons on the PED minimum may exhibit more "atomic-like" behavior. Alternatively, the difference may be a consequence of different probing depths on and off the PED maximum, and hence the sampling of different scattering sites. Experiments to discriminate between these possibilities are currently underway. This work is supported by NSF-DMR 98-01681 and NATO-CRG 97-0175.