Plasmon-Mediated Energy Transfer and Super-Resolution Imaging in the Near Field of Nanostructured Materials
January 17th, 2018 DORIAN BOUCHET Institut Langevin ESPCI Paris-CNRS

The decay rate of a fluorescent emitter is not an intrinsic emission property but it can be either enhanced or reduced, depending on the local environment of the emitter. For instance, optical antennas can be designed to enhance the rate of spontaneous emission, in order to obtain bright nanosources emitting photons at a high rate. In biology, several applications including sensing and imaging techniques are based on the determination of decay rate variations induced by the environment. In this context, we performed experimental measurements and data modelling to study the decay rate and the energy transfer rate for fluorescent emitters in nanostructured environments. Firstly, we showed that simple plasmonic nanostructures can be used to achieve micrometrerange energy transfer between fluorescent emitters. We notably investigated plasmon-mediated energy transfer between ensembles of fluorescent emitters located in the near field of a silver mirror. We also coupled a single quantum dot and a fluorescent nanobead to a silver nanowire and we studied evidences of the energy transfer between the two emitters, separated by several micrometres. We notably demonstrated a correlated blinking of the two emitters through the study of the correlation function of their fluorescence intensity.

Secondly, we introduced a stochastic technique inspired by photo-activated localisation microscopy in order to probe the sub-wavelength spatial variations of the decay rate induced by nanostructured environments. As a proof-of-principle experiment, we applied the technique to photo-activated molecules located in the near field of a silver nanowire. As a result, we obtained a decay-rate map showing a typical localisation precision of the order of 10 nm. We then used the Fisher information to estimate lower bounds on the standard errors on position and decay rate estimates, thus providing guidelines in order to perform fluorescence lifetime mapping with optimal precision.

Seminar, January 17, 2018, 12:00. ICFO’s Seminar Room.

Hosted by Prof. Niek van Hulst