Superresolution optical fluctuation imaging (SOFI) aided nanomanipulation of quantum dots using AFM for novel artificial arrangements of chemically functionalized colloidal quantum dots and plasmonic structures

Abstract

For single photon experiments or research on novel hybrid structures consisting of several colloidal quantum dots (Qdots) and plasmonic nanoparticles both the precise localization and the optical behavior of the emitters need to be correlated. Therefore, the gap between the high spatial resolution topography information that provides detailed localization of single Qdots and the diffraction limited fluorescence image needs to be overcome. In this paper, we demonstrate the combination of atomic force microscopy (AFM) with wide-field fluorescence microscopy improved by superresolution optical fluctuation imaging (SOFI). With this approach the topography and the superresolution image can be overlaid with sub-diffraction precision. Consequently, we discriminate between single Qdots that are optically active and dark ones. Additionally, the optical time-dependent behavior of molecular emitters can be selectively investigated. This method is, furthermore, useful for an advanced manipulation and characterization toolbox of Qdots in general. In summary, our findings represent an easily adaptable, highly reproducible and comparatively cheap subdiffraction limit imaging method and they facilitate the efficient selection of bright Qdots in a standard lab environment for proof-of-principle nanostructures containing Qdots and for nanomanipulation experiments.