Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 41: Poster Session I (Semiconductor Substrates: Epitaxy and growth; Semiconductor Substrates: Adsorbtion; Semiconductor Substrates: Solid-liquid interfaces; Semiconductor Substrates: Clean surfaces; Oxides and insulators: Epitaxy and growth; Oxides and insulators: Adsorption; Oxides and insulators: Clean surfaces; Organic, polymeric and biomolecular films - also with adsorbates; Organic electronics and photovoltaics, Surface chemical reactions; Heterogeneous catalysis; Phase transitions; Particles and clusters; Surface dynamics; Surface or interface magnetism; Electron and spin dynamics; Spin-Orbit Interaction at Surfaces; Electronic structure; Nanotribology; Solid/liquid interfaces; Graphene; Others)
O 41.62: Poster
Dienstag, 23. März 2010, 18:30–21:00, Poster B1
Characterisation and setup of a noncollinear optical parametric amplifier and investigation of ultrafast dynamics of Na/Cu(111) — •Daniel Wegkamp1,3, Marcel Krenz1,3, Uwe Bovensiepen2,3, and Martin Wolf1,3 — 1Fritz Haber Institute of the MPG, Dept. of Physical Chemistry, Berlin, Germany — 2Universität Duisburg-Essen, Dept. of Physics, Duisburg, Germany — 3Freie Universität Berlin, Dept. of Physics, Berlin, Germany
To study ultrafast dynamics on a femtosecond timescale, laser pulses of comparable and shorter scale are used in this work in combination with 2-photon photoemission. Here, we report the principle, setup, and characterisation of a femtosecond light-source based on a noncollinear optical parametric amplifier (NOPA) and its application in studying the dynamics of Na/Cu(111) following [1]. Laser pulses with duration < 20 fs have been generated in the visible spectral range using a 300 kHz regenerative amplifier. In a single color scheme (hν=2.3 eV) the NOPA pulses are used to excite and photoemit hot electrons, which are detected with a time of flight (TOF) spectrometer. With time independent measurements the binding energy of the adsorbate-induced resonance at 2 eV is observed in agreement with [2]. As a function of pump-probe delay a time-dependent binding energy shift of the Na resonance with -2 meV/fs is observed. This shift is explained as a pump-induced movement of the sodium adsorbate away from the surface. All experiments were conducted at the Freie Universität Berlin.
[1] H. Petek et al., Science 288 (2000) 1402
[2] N. Fischer et al., Surf. Sci. 314 (1994) 89