Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: POSTER: INTERNAL SYMPOSIUM Optical Spectrosopy

CPP 22.9: Poster

Wednesday, March 28, 2007, 16:00–18:30, Poster B

Femtosecond Resolved Transient Absorption Spectroscopy of Silicon Quantum Dots — •Volker Kuntermann^1,2, Carla Cimpean¹, Dietrich Haarer², and Carola Kryschi¹ — ¹Department for Physical Chemistry I, Friedrich-Alexander-Universität — ²Experimentalphysik/BIMF, Universität Bayreuth

We report about femtosecond resolved transient absorption spectroscopy of quantum dot semiconductor nanoparticles. The silicon nanoparticles with a diameter of 5 nm were synthesized by a gas phase process. The diameter is in the order of the exciton radius. The time resolved experiments are always in the limit of strong confinement. Performing stationary fluorescence spectroscopy we find two characteristic bands, which arise on the one hand from bulk excitons of the nanoparticles and on the other hand from surface states in the outer shell. The basis for all possible applications, e.g. photovoltaics, is a well defined and stable surface. With time resolved spectroscopic investigations we get insight in the surface quality and in the passivation of the quantum dots since the observed surface luminescence is highly sensitive to physisorbed compounds (e.g. different functionalisations).