Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter. Our current focus is on detection and sensing/imaging with an emphasis on the development of integrated photonics. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.


Molecular fluorescence lifetime fluctuations: on the possible role of conformational effects

(full pdf)

Vallee RAL, Vancso GJ, van Hulst NF, Calbert JP, Cornil J, Bredas JL
vol 372 issue 1-2: p282-p287 APR 22 2003

The radiative lifetime of single 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine molecules, embedded in a polymer thin film, has been characterized. At room temperature the chemically identical molecules exhibit strong fluctuations in their fluorescence lifetime. The possible conformational origin of these fluctuations has been addressed by semi-empirical quantum-chemical calculations. Specifically, the impact of conformational effects induced by thermal motion o­n the transition energy and the value of the transition dipole moment has been studied. The results indicate that the strong fluctuations cannot be explained by pure thermally activated conformational changes. Since quenching mechanisms are not responsible for the observed fluctuations, we suggest that molecular segmental dynamics of the surrounding polymer play a key role in determining the lifetime fluctuations. (C) 2003 Elsevier Science B.V. All rights reserved.
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