Optics With Nano-Sized Structures Made From Semiconductors and (Noble) Metals

Abstract

We summarize some of our efforts in synthesizing and characterizing nanoscopic objects fabricated from semiconducting materials and noble metals. The optical properties of colloidal semiconductors (quantum dots) are analyzed, in particular, with respect to their spectral photoluminescence properties (bandgap engineering) and the characteristic emission blinking. The statistical evaluation of the on- and off-states seen in the time-dependent recordings of the photoluminescence emitted from a single nanoparticle confirmed the reported power-law probability distribution, however, with a superimposed decay of the on-state density (which is illumination intensity dependent). This results in a loss of fluorescence intensity upon extended illumination when these particles are used in biosensor assays. Next, a colloid particle-based template protocol for the fabrication of non-trivial Au nanostructures is described. The resulting nano-crescents can be varied in terms of their size and shape. It is demonstrated how their plasmonic resonance characteristics can thus be tuned with respect to the spectral position of their (multipole) absorbance peaks, and their polarization properties.