Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 58: Poster Session III (Solid/liquid interfaces; Metals; Semiconductors; Oxides and insulators)
O 58.24: Poster
Mittwoch, 28. März 2012, 18:15–21:45, Poster B
Plasmonic light emission boosted by the charging of a molecule — Alexander Kabakchiev1, Theresa Lutz1, •Christian Dette1, Christoph Große1, Klaus Kuhnke1, Uta Schlickum1, and Klaus Kern1,2 — 1Max-Planck-Institut für Festkörperforschung, D-70569 Stuttgart, Germany — 2Institut de Physique de la Matière Condensée, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
The efficiency of light generation in a scanning tunneling microscope (STM) can depend on the accumulated charge on an individual organic molecule. We employ STM in ultra-high vacuum at liquid helium temperature to study tunnel-current-induced luminescence on the single molecule level. fac-Ir(ppy)3 molecules deposited on a C60 double layer on Au(111) are investigated by spatially resolved differential conductance spectroscopy and luminescence spectroscopy. We observe that individual Ir(ppy)3 molecules are surrounded by an extended area in which the light emission is boosted by up to two orders of magnitude above the emission on the C60 layer. This area increases with the applied bias voltage. Optical spectroscopy reveals that the luminescence is not intrinsic to Ir(ppy)3 but is due to locally excited tip-induced plasmons. Differential conductance maps exhibit a strong ring-like feature which coincides with the margins of the area of enhanced luminescence. We demonstrate that the efficiency of plasmon generation can thus be controlled by a reversible electric-field-induced elementary charge transfer.