Interrogation of Reactions and Processes on the Nanoscale via Single Nanoparticle Spectroscopy

 Interrogation of Reactions and Processes on the Nanoscale via Single Nanoparticle Spectroscopy

Abstract: 

The advent of ultra-sensitive detectors has enabled the development of techniques to allow the detection and interrogation of chemicals on the single molecule (and single particle) scale. These techniques are particularly applicable and useful for nanoparticle samples due to the size and shape polydispersity present in even the best chemically synthesised colloidal samples. We have recently been using single particle spectroscopy to investigate systems such as fluorescent CdSe nanocrystals as well as non-fluorescent gold nanocrystals. In this presentation, an overview of single particle spectroscopy techniques will be given. The optical properties of these classes of particles at the single crystal level will be discussed, including their size and shape dependence and the importance of passivation via ligation and shelling for CdSe. A method to routinely correlate the spectra of gold nanoparticles to the exact size and shape of the nanoparticles has been developed and will be described. This method has allowed direct comparison between theory (the discrete dipole approximation, DDA) and experiment.

These single particle investigations have been extended to include the detection of energy and electron transfer reactions on single particles. Some examples include energy transfer between single CdSe nanocrystals and a molecular dye, the growth of gold nanorods (detected in situ), Au catalysed electron transfer processes and the electrochemical charging of gold nanorods. These results will be presented and discussed.

 Speaker: Alison M. Funston

 Affiliation: NanoScience Laboratory, Bio21 Institute and School of Chemistry, The University of Melbourne, Australia

 Host: Isabel Abreu – Plant Genetic Engineering Laboratory