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O: Oberflächenphysik

O 14: Poster session I (Adsorption, Epitaxy and growth, Phase transitions, Surface reactions, Organic films, Electronic structure, Methods) (sponsored by Omicron Nanotechnology GmbH)

O 14.75: Poster

Montag, 27. März 2006, 18:00–21:00, P2

Investigation of polymer structures with a 2-photon photoelectron emission microscope (2P-PEEM) — •Christoph Senft, Jens Schütte, Lilienkamp Gerhard, and Daum Winfried — Institut für Physik und Physikalische Technologien, TU Clausthal, Leibnizstrasse 4, D-38678 Clausthal-Zellerfeld

Our photoelectron emission microscope (PEEM) has been combined with a femtosecond Ti:sapphire laser system for surface imaging using 2-photon photoemission (2PPE). A home-built frequency conversion system provides 100 fs pulses at the second, third and fourth harmonic wavelength of the laser. Energy-filtered images of the surface are obtained with an electrostatic double-90^∘ energy filter. Recently, *hot spots* have been reported in a 2P-PEEM study of silver particles on silicon and assigned to plasmon excitations in the particles [1]. We have observed similarily enhanced 2P-PEEM intensities from polystyrene particles on platinum. A marked increase of 2PPE intensity at small wavelengths of excitation can be explained by HOMO-LUMO transitions in the polymer particles. We did not find indications for Mie-resonances in the particle-surface system. We will also discuss the behavior of dielectrics in a PEEM such as energy shifts and charging under femtosecond laser illumination.

[1]: O. Schmidt et al., Appl. Phys. B74 (2002) 223