Addressing the out-of-equilibrium dynamics of nano-objects with plasmon-enhanced spectroscopy

Materials out of thermodynamic equilibrium are at the heart of many established and emerging technologies, from lasers to plasmon-driven hot electron photochemistry. At the nanoscale, the characterization of out-of-equilibrium dynamics is crucial, but often remains challenging because it requires combining ultrafast and highly sensitive detection techniques.

In this seminar, we introduce two new spectroscopy approaches to out-of-equilibrium nanomaterials both leveraging plasmonic nanocavities to enhance light-matter interaction. We present their theoretical foundations and recent results from our experimental collaborators. First, we discuss the characterization of energy redistribution in the ground state of molecules using surface-enhanced infrared and Raman spectroscopies in plasmonic nanogap cavities. Second, we show that the photoluminescence emitted by metallic nanostructures under femtosecond laser pumping gives access to the ultrafast dynamics of their hot carriers. Taken together, these approaches open new routes to a better understanding of out-of-equilibrium phenomena in nanophotonics.