Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 6: Nanostrukturen I

O 6.4: Vortrag

Montag, 24. März 2003, 12:00–12:15, M\"UL/ELCH

Observation of Cu Surface Inhomogeneities by Multi-Photon Photoemission Spectro-Microscopy — •M. Cinchetti, A. Oelsner, G.H. Fecher, H.J. Elmers, and G. Schönhense — Institut für Physik, Johannes Gutenberg Universität, D-55099 Mainz, Germany

The spatially resolved energy distribution of electrons emitted from a polycrystalline copper surface has been studied by multi-photon photoemission. Electron emission was induced by femtosecond laser pulse excitation and detected by a photoemission electron microscope combined with a time-of-flight detector to allow spatially resolved energy analysis. The energy dispersion curves obtained from small spots with strongly enhanced electron emission yield (so called hot spots) turned out to be completely different from those measured for larger, homogeneous surface regions. The latter directly reflect two photon photoemission spectra from Cu as was previously observed in spatially averaging experiments. The hot spots are characterized by rather narrow energy distributions. The peak positions of these spectra do not depend on the photon energy as is expected for a true secondary process. This indicates clearly a different electron emission mechanism in the hot spots compared to homogeneous surfaces.