The ability to routinely confine light to nanoscale volumes around molecules using plasmonic nanocavities opens up a wide landscape to explore optomechanical coupling. In this talk I will explore the capabilities and vision.

We have exploited a nanoparticle-on-mirror configuration to create thousands of identical nanocavities.[1] Embedding self-assembled monolayers of molecules in these nanocavities allows exploration of how they vibrationally couple (including at THz frequencies),[2,3] how they can be optomechanically-pumped,[4,5] how they can create new modes,[6] and how they can transport heat. We also explore the vibrational coupling of molecules with radical electrons, to access a new generation of qubits which can operate at room temperature.[7]

We also show applications ranging from photocatalysis to sensing. These have been enabled by a new discovery that we can completely clean out and reinsert molecules in nanogaps repeatedly, producing ideal SERS substrates which can be operated in flow with electrochemical control.[8] Monolayers of water on the gold nanogap facets can be tracked, allowing their orientation and hydrogen-bonding to be studied in situ, and sensitising for ultralow gas/vapour detection.

[1] JJ Baumberg et al, Nature Materials 18, 668 (2019); DOI: 10.1038/s41563-019-0290-y
[2] NS Muller et al, Nano Letters (2022); DOI: 10.1021/acs.nanolett.2c02806
[3] A Boehmke et al, Nature Comm (2024); DOI: 10.1038/s41467-024-50823-x
[4] L Jakob et al, Nature Comm 14, 3291 (2023); DOI 10.1038/s41467-023-38124-1
[5] L Jakob et al, ACS Nano (2025); DOI: 10.1021/acsnano.4c16535
[6] R Arul et al, PRL (2023); DOI: 10.1103/PhysRevLett.131.126902
[7] Y Bar-David et al, ACS Nano 19, 7650 (2025); DOI: 10.1021/acsnano.4c09661
[8] S Sibug-Torres et al, Nature Comm. (2024); DOI: 10.1038/s41467-024-46097-y