Berlin 2005 – wissenschaftliches Programm
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O: Oberflächenphysik
O 12: Nanostrukturen I
O 12.1: Vortrag
Freitag, 4. März 2005, 15:45–16:00, TU EB202
PEEM as a tool for the investigation of optical near fields — •M. Cinchetti1, A. Gloskovskii1, S. Nepijko1, G. Schönhense1, M. Kreiter2, H. Rochholz2, D. Bayer3, C. Wiemann3, M. Bauer3, and M. Aeschlimann3 — 1Institut für Physik, Johannes Gutenberg-Universität Mainz — 2MPI für Polymerforschung Mainz — 3Institut für Physik, Universität Kaiserslautern
Photoemission electron microscopy (PEEM) was used to image the electrons photoemitted from specially tailored Ag nanoparticles (crescents, dots, rods) deposited alternatively on a Si substrate with its native oxide (SiOx) or on an ITO substrate. Photoemission was induced by illumination with a Hg UV-lamp (photon energy cutoff ℏωUV=5.8 eV, wavelength λUV≥ 220 nm) and with a Ti:Sa femtosecond laser (ℏωl=3.0 eV , λl=400 nm), respectively. Upon illumination at energies above the Ag plasmon frequency the photoemission from the nanoparticles appears rather homogeneous. In contrast, at lower photon energies a strongly spatially localized photoemission signal is recorded. For 400 nm laser radiation the electron emission results from two-photon photoemission as was previously demonstrated by PEEM spectromicroscopy [1]. The results are interpreted as a signature of the local electrical field thus providing a tool to map the optical near field with the resolution of emission electron microscopy.
[1] M. Cinchetti et al. , Appl. Phys. Lett. 83 (2003) 1503 and J. El. Spectr. Rel. Phen. 137-140 (2004) 249.