Colloquium: Paul Mulvaney FAA FRSC
Location
Physics : 401
Date & Time
April 1, 2015, 3:30 pm – 4:30 pm
Description
TITLE: Gold Nanocrystals: Single Particle Catalysis, Energy Transfer and Superlattice Dynamics
ABSTRACT: In this talk I will provide an overview of some of our recent work on three aspects of the chemistry of gold nanocrystals. In the first part we study chemical reactions on single nanoparticles. We show how electron transfer can be observed spectroscopically and how even processes such as hydrogen adsorption can be detected. We show that the interaction of the metal nanocrystal with the support matrix is crucial in determining reactivity. We will illustrate a method called capillary force assembly for creating libraries of single catalyst particles. In the second system we study energy transfer from dye molecules to metal particles. We have used silica as a nanoscale spacer. We show that for small gold particles (15nm in size) the gold particle acts as a quencher at all separations. Full electrodynamic calculations agree well with experiment and show that quenching obeys a d-4 distance dependence. Finally, we will briefly describe NIPAM spacers as a temperature-tunable spacer. The use of polymer shells to control surface plasmon interactions is discussed and the possibility of light driven chemistry in plasmonic systems by local plasmonic heating. We demonstrate nanosecond based superlattice melting as a means to study the dynamics of colloidal crystal formation.
ABSTRACT: In this talk I will provide an overview of some of our recent work on three aspects of the chemistry of gold nanocrystals. In the first part we study chemical reactions on single nanoparticles. We show how electron transfer can be observed spectroscopically and how even processes such as hydrogen adsorption can be detected. We show that the interaction of the metal nanocrystal with the support matrix is crucial in determining reactivity. We will illustrate a method called capillary force assembly for creating libraries of single catalyst particles. In the second system we study energy transfer from dye molecules to metal particles. We have used silica as a nanoscale spacer. We show that for small gold particles (15nm in size) the gold particle acts as a quencher at all separations. Full electrodynamic calculations agree well with experiment and show that quenching obeys a d-4 distance dependence. Finally, we will briefly describe NIPAM spacers as a temperature-tunable spacer. The use of polymer shells to control surface plasmon interactions is discussed and the possibility of light driven chemistry in plasmonic systems by local plasmonic heating. We demonstrate nanosecond based superlattice melting as a means to study the dynamics of colloidal crystal formation.