Switching plasmonic nanogaps between classical and quantum regimes with supramolecular interactions

Area of Science:

• Extreme nanophotonics
• Quantum plasmonics
• Supramolecular chemistry

Background:

• Nanogap plasmons offer field enhancements up to 1000x, enabling single-molecule and single-atom studies.
• Modulating quantum plasmonics is challenging due to the lack of effective sub-nanometer gap actuators.

Purpose of the Study:

• To demonstrate supramolecular systems for reversible control of plasmonic nanogaps.
• To investigate the transition between classical and quantum tunneling regimes in plasmonic nanogaps.

Main Methods:

• Utilizing oligoamide supramolecular systems as reversible spacers between gold nanoparticles and a mirror.
• Analyzing plasmon shifts near the quantum tunneling limit using classical and quantum-corrected models.
• Investigating the role of plasmonic hot electron tunneling in modulating quantum plasmons.

Main Results:

• Supramolecular systems successfully switched gap plasmons between classical and quantum tunneling regimes.
• Observed plasmon shifts near the quantum tunneling limit, consistent with theoretical models.
• Demonstrated that plasmonic hot electron tunneling causes a blue shift in quantum plasmons.

Conclusions:

• Oligoamide supramolecular systems provide a novel method for actuating sub-nanometer gaps in plasmonic devices.
• The findings offer a promising prototype for optically tunable quantum plasmonic devices.
• This work advances the understanding and control of quantum phenomena in nanophotonics.