Through synergizing the responsiveness of functional molecules to external excitations and the nanoscale modulation of light via surface plasmons on metal nanoparticles, hybrid molecule-nanoparticle systems can function as smart nanomaterials for a wide range of applications such as biochemical detection, drug delivery, and energy conversion. However, accomplishment of this synergy still relies on the improved understanding of molecule-nanoparticle interactions and capability of controlling functional molecules on metal nanoparticles. Herein, using photoswitchable azobenzene (AZO) as model molecules, we report our recent advances in designing, measuring and controlling single molecules or precise molecular assemblies on single metal nanoparticles. Specifically, we have extended the directed and self-assembly strategies that we learned from the studies of molecules on atomically flat Au thin films to Au nanoparticles. Advanced characterization tools that integrate scanning tunneling microscopy and plasmon-enhanced optical spectroscopy have been employed to measure the structures, dynamics, and functions of AZO as single molecules or precise molecular assemblies on single Au nanoparticles. The photoswitchable molecule-nanoparticle interactions and their effects on the optical properties of the hybrid molecule-nanoparticle systems are also investigated. The experimental data coincide with theoretical calculations. Our single-molecule and single-nanoparticle studies help eliminate the inevitable heterogeneity from ensemble measurements and provide a new insight into the structure-property relations of hybrid molecule-nanoparticle systems.

Rational design and control of functional molecules on single metal nanoparticles

249th National Meeting (2015)

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