Abstract
Since the pioneering work of Purcell, it has been demonstrated in many different situations that the spontaneous emission rate of a single emitter (e.g., atom, molecule, quantum dot) depends on the environment. The advent of near-field optics techniques has made possible the detection and spectroscopy of single molecules in complex environments, with a lateral resolution below 100 nm. Near-field optics also stimulated the use of sharp metallic tips or nanoparticles to modify the lifetime and to enhance (or quench) the fluorescence of single molecules. The role of such nanoantennas is twofold: an enhancement of the exciting local intensity, and a modification of the radiative emission rate, both in amplitude (Purcell effect) and angular dependence. A drawback when using metallic objects is the presence of absorption, which creates additional non-radiative channels. In the case of small nanoparticles, we have studied recently the trade-off between radiative and non-radiative processes using a dipole-dipole model [1]. This study has shown that the non-radiative decay rate follows a R-6 dependence at short range, where R is the distance between the emitter and the center of the nanoparticle, whereas the distance dependence of the radiative decay rate is more subtle. It is chiefly dominated by a R-3 dependence, a R-6 dependence being visible at plasmon resonance. This distance dependence might be used to control fluorescence lifetimes and fluorescence signals emitted by single molecules. Nevertheless, substantial influence of the nanoparticle on the emitter dynamics is obtained at distances on the order of a few nanometers. This can be a severe limitation, e.g., when the molecule is embedded in a substrate or in a biological medium.
© 2007 IEEE
PDF ArticleMore Like This
L. S. Froufe-Pérez and R. Carminati
WB4 Photonic Metamaterials: From Random to Periodic (META) 2007
Cédric Vandenbem, Luis S. Froufe-Pérez, and Rémi Carminati
QTuA6 Quantum Electronics and Laser Science Conference (CLEO:FS) 2008
L. S. Froufe-Pérez, J. J. Sáenz, and R. Carminati
QTuK2 Quantum Electronics and Laser Science Conference (CLEO:FS) 2007