Open AccessLifetime of fluorescent dye molecules in dense aqueous suspensions of polystyrene nanoparticles
Author(s) -
Giuseppe Scalia,
Frank Scheffold
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.029342
Subject(s) - quantum yield , polystyrene , fluorescence , materials science , aqueous solution , alexa fluor , nanoparticle , particle (ecology) , sodium dodecyl sulfate , chemical engineering , particle size , photochemistry , dispersion (optics) , molecule , analytical chemistry (journal) , chemistry , nanotechnology , chromatography , optics , organic chemistry , composite material , polymer , physics , oceanography , engineering , geology
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.