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

Renaud A.L. Vallée*, G. J. Vancso, N. F. van Hulst, J. P. Calbert, J. Cornil, J. L. Brédas

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)282-287
Number of pages6
JournalChemical Physics Letters
Issue number1-2
StatePublished - Apr 22 2003
Externally publishedYes

Bibliographical note

Funding Information:
R.A.L. Vallée is grateful to the Council for Chemical Sciences of the Netherlands Organization for Scientific Research (NWO-CW) for supporting this research. The work in Arizona is supported by the National Science Foundation (CHE-0078819), the Petroleum Research Fund, and the IBM Shared University Research Program. The work in Mons is supported by the Belgian Federal Government ‘InterUniversity Attraction Pole in Supramolecular Chemistry and Catalysis (PAI 4/11)’, and the Belgian National Fund for Scientific Research (FNRS-FRFC). J.C. is an FNRS research associate; J.P.C. acknowledges a grant from the Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture (FRIA).

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


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