Exploring properties of few molecules in tightly-confined plasmonic nanocavities

This project aims to study the influence of magnetic fields, thermal gradients, and infra-red light on the optical properties of molecules in the sub-nm plasmon gaps between metallic components that trap light. Underneath a 60-100nm diameter Au nanoparticle on mirror, the 100 molecules in a self-assembled monolayer experience a highly confined optical field. Their complex refractive index controls the optical modes seen in dark field scattering, as well as the signatures seen in surface-enhanced Raman spectroscopy (SERS).

In this project you will explore some of the control parameters that can modify the refractive index of these molecules, in order to tune the optical modes rapidly, and potentially to deliver low energy optical switching. At the same time, this should develop fundamental understandings of light-matter coupling on the nanoscale in ambient environments in many aspects are unknown. The first control parameter will be the magnetic field applied to the system. The second area to develop is the effect of thermal gradients across single molecule layers. A third area to explore is the use of tuneable infrared lasers (5-11um wavelength) on the molecules inside the NPoM. These all have implications for using molecular plasmonics in low energy IT devices as well as fundamental science.