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Lifetime of fluorescent dye molecules in dense aqueous suspensions of polystyrene nanoparticles

  • Scalia, Giuseppe Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
  • Scheffold, Frank Department of Physics and Fribourg Center for Nanomaterials, University of Fribourg, Switzerland
    16.11.2015
Published in:
  • Optics Express. - 2015, vol. 23, no. 23, p. 29342
English We study the lifetime of two common fluorescent dye molecules from the Alexa Fluor NHS Ester family dissolved in water in an opaque aqueous dispersion of dielectric polystyrene nanoparticles. We investigate the role of the dispersion composition by varying the particle concentration and adding SDS (sodium dodecyl sulfate) surfactant molecules. The observed strong changes in lifetime of Alexa 430 can be attributed to the relative contribution of radiative and non-radiative decay channels while the lifetime of the Alexa 488 dye depends only weakly on the sample composition. For Alexa 430, a dye with a rather low quantum yield in aqueous solution, the addition of polystyrene nanoparticles leads to a significant enhancement in quantum yield and an associated increase of the fluorescent lifetime by up to 55 %. We speculate that the increased quantum yield can be attributed to the hydrophobic effect on the structure of water in the boundary layer around the polystyrene particles in suspension. Adding SDS acts as a quencher. Over a range of particle concentrations the particle induced increase of the lifetime can be completely compensated by adding SDS.
Faculty
Faculté des sciences et de médecine
Department
Département de Physique
Language
  • English
Classification
Physics
License
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Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/304647
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