Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 28: Postersitzung (Elektronische Struktur, Grenzfläche fest-flüssig, Halbleiteroberflächen und -grenzflächen, Magnetismus und Symposium SYXM, Methodisches, Nanostrukturen, Oberflächenreaktionen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie)

O 28.75: Poster

Mittwoch, 10. März 2004, 16:00–19:00, Bereich C

Time-of-Flight Two-Photon Photoemission Spectromicroscopy of Noble metal cluster films with Femtosecond Laser Radiation. — •M. Cinchetti, A. Gloskovskii, D. A. Valdaitsev, S. A. Nepijko, and G. Schönhense — Johannes Gutenberg-Universität, Institut für Physik, 55099 Mainz, Deutschland

Time-of-Flight Two-Photon Photoemission Spectromicroscopy [1] was used to investigate the photoemission properties of some Nobel metal surfaces under femtosecond laser irradiation (photon energy 3.1 eV, pulse width < 200 fs, laser fluence 6.4 µJcm⁻²).In particular, we present the results of investigations of Cu surface inhomogeneities and Ag nanoparticle films deposited on a Si(111) substrate. The photoemission yield resulted to be enhanced in presence of surface inhomogeneities with dimensions in the nanometer range. The energy distribution curves obtained from regions characterized by a strongly enhanced photoemission yield are shown to have the same qualitative behaviour. They differ significantly from the energy distribution curves from the homogeneous and clean metal surfaces. The differences are explained in terms of (i) a reduction of surface potential barrier connected with the appearance of local fields between the nanoparticles and the substrate; (ii) the excitation of Localized Surface Plasmons in the nanoparticles and the consequent modification of the near field [2], that influences the photoemission. [1] M. Cinchetti, A. Oelsner, G. H. Fecher, H. J. Elmers, and G.Schönhense, Appl. Phys. Lett. 83, 1503 (2003). [2] V.M. Shalaev, C. Douketis, T. Haslett, T. Stuckless, and M. Moskovitis, Phys. Rev. B 53, 11193 (1996).