Abstract: Our ability to trap light into extreme nanoscale gaps between coinage metals using plasmonics has enabled routine vibrational measurements of molecular monolayers, even within active molecular electronics devices. I show how plasmonically-enhanced light-induced van-der-Waals forces pulls single adatoms from metal facets, to create ​‘picocavities’ which confine light to volumes smaller than a single atom. The thousand-fold stronger optical forces depend on both nearby molecules and local optical field. Coordination bonds with individual molecules can be tracked in real time or their fluctuating redox state observed. Such spectroscopy reveals a wealth of information, from how voltages twist conducting molecules, to how catalysis operates at individual adatoms. 

Bio: Jeremy J. Baumberg FRS, is the Harald Aspden Professor of Fundamental Physics at the University of Cambridge, directing a key UK NanoPhotonics Centre.