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CPP: Chemische Physik und Polymerphysik

CPP 2: Single Molecule Spectroscopy

CPP 2.4: Talk

Tuesday, April 3, 2001, 16:45–17:05, 110

Orientation dependent lifetimes of single fluorophores in planar multilayered systems — •Maximilian Kreiter, Michael Prummer, Bert Hecht, and Urs P. Wild — Physical Chemistry Laboratory, ETH-Zentrum, Universitätsstrasse 22, CH-8092 Zürich, Schweiz

It is well established that the emission characteristics of an excited fluorophore is strongly influenced by a nearby interface between two dielectrics[1]. We use a scanning confocal microscope with annular illumination to access the three-dimensional orientation of single dye molecules in a polymer matrix directly[2]. Simultaneously, the fluorescence lifetime of the molecule is measured. An increase in lifetime of the molecules oriented perpendicular to the interface compared to parallel orientation is observed. The results are interpreted by modelling the chromophore as an oscillating dipole in stratified dielectric media. The correspondence between theory and experiment is good when radiationless transition processes are included in the analysis. This leads to the conclusion that such orientation effects are one main contribution to the variations in the fluorescence lifetime of molecules near interfaces.

[1] W. Lukosz, Phys. Rev. B, 22, 3030 (1980)

[2] B. Sick, B. Hecht, L. Novotny, Phys. Rev. Lett., 85, 4482 (2000)