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Q: Fachverband Quantenoptik und Photonik

Q 55: Poster II

Q 55.36: Poster

Donnerstag, 11. März 2010, 16:00–19:00, Lichthof

Controlling single-molecule dipole-dipole coupling by optical confinement in a λ/2-microresonator (exchanged with Q 67.1) — •Raphael Gutbrod, Sebastian Bär, Frank Schleifenbaum, Sébastien Peter, Kirstin Elgass, and Alfred J. Meixner — Institute of Physical and Theoretical Chemistry, University of Tübingen

Fluorescence resonance energy transfer (FRET) is a well-known photophysical phenomenon where the excited-state energy from the initially excited donor molecule is transferred to an acceptor molecule via dipole-dipole coupling. The rate of energy transfer depends upon the extent of spectral overlap of the donor emission spectrum with the acceptor absorption spectrum, the quantum yield of the donor, the relative orientation of the donor and acceptor transition dipoles and the distance between donor and acceptor and hence is often used as a molecular ruler in fluorescence microscopy in life-sciences. We present a novel approach to precisely tune the FRET efficiency by the local mode of a subwavelength Fabry-Pérot type microresonator. According to Fermi's golden rule, the spontaneous emission rate depends on the mode density of the electromagnetic field and can be modified in the microresonator. Thus, the fluorescence of the chromophores involved in the FRET-process is varied over a broad range. We demonstrate that a microresonator disentangles coupled FRET systems by gradually varying the energy transfer from donor to acceptor. It is possible to tune the energy transfer rate of a given FRET-pair without chemical or physical manipulation of the dye system by simply varying the mirror separation of the microresonator.