title: Enhancement and quenching of single-molecule fluorescence.
abstract: We present an experimental and theoretical study of the fluorescence rate of a single molecule as a function of its distance to a laser-irradiated gold nanoparticle. The local field enhancement leads to an increased excitation rate whereas nonradiative energy transfer to the particle leads to a decrease of the quantum yield (quenching). Because of these competing effects, previous experiments showed either fluorescence enhancement or fluorescence quenching. By varying the distance between molecule and particle we show the first experimental measurement demonstrating the continuous transition from fluorescence enhancement to fluorescence quenching. This transition cannot be explained by treating the particle as a polarizable sphere in the dipole approximation.
authors.affiliation: The Institute of Optics and Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627, USA.
authors.forename: Pascal
authors.initials: P
authors.lastname: Anger
authors.forename: Palash
authors.initials: P
authors.lastname: Bharadwaj
authors.forename: Lukas
authors.initials: L
authors.lastname: Novotny