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O: Fachverband Oberflächenphysik

O 46: Plasmonics and Nanooptics I

O 46.5: Vortrag

Mittwoch, 2. April 2014, 11:30–11:45, TRE Phy

Resonance enhanced local thermionic emission — •Felix Becker, Dominik Differt, Matthias Hensen, Christian Strüber, and Walter Pfeiffer — Molecular and Surface Physics, Department of Physics, Bielefeld University, 33615 Bielefeld, Germany

In the interaction of intense laser pulses with nanostructures or optical antennas the electron emission is commonly discussed in the context of multi-photon processes and strong field phenomena. However, resonant excitation and the related field enhancement also significantly increase the locally absorbed energy density leading to a transient local heating of the electron gas. Thermionic emission dominates the electron yield for sufficiently strong excitation. This has been demonstrated recently for nanoantenna induced currents in metal-insulator-metal junctions and for photonic resonances in nanotextured amorphous silicon layers. Based on electron-electron and electron-phonon scattering rates transient electron energy distributions after short pulse excitation and the related thermionic emission over an internal tunnel barrier and for electron emission into the continuum are simulated. Variation of both scattering rates determines the ratio between sequential multiphoton photoemission and thermionic emission following the Richardson-Dushman equation. Despite the incoherent character of thermionic emission it can be exploited as a probe for this energy concentration process.