Physics in Nanogaps

Understanding light-matter interactions within plasmonic nanogaps

Self-assembled nanoparticle structures enable the creation of versatile nanoscale plasmonic gaps with different species “sandwiched” in them. These nanogaps serve as a playground for looking at a variety of exotic light-matter interactions using techniques like surface-enhanced Raman and dark field spectroscopy. High plasmonic enhancement and low numbers of molecules in the gaps help us gain fundamental understanding in directions such as collective dye photoluminescence, spin state control in radical molecules, single-molecule spectroscopy of protein and viral species and light-driven metal adatom (“picocavity”) dynamics.

Nanoparticle-on-mirror plasmonic nanogap containing a single dye molecule. Adapted from [3].
Above: Light-driven Au adatom (picocavity) in plasmonic nanogap and resulting SERS modulation (above). Adapted from [1].
Right: The relative adatom-molecule trajectory reconstructed from picocavity SERS spectra in real time. Adapted from [4].

[1] Lin et al, Optical suppression of energy barriers in single molecule-metal binding, Science Advances, 2022, 8, 25

[2] Elliot et al, Fingerprinting the hidden facets of plasmonic nanocavities, ACS Photonics,  2022, 9, 8, 2643–2651

[3] Chikkarady et al, Single-molecule strong coupling at room temperature in plasmonic nanocavities, Nature, 2016, 535, 127–130

[4] Griffiths et al, Resolving sub-angstrom ambient motion through reconstruction from vibrational spectra, Nature Comm., 2021, 12, 6759

People working on the topic: Lille Borresen, Jonathan Bar David, Taras Mykytiuk, Paul Kerner, Martin Stecher, Riccardo Nori