Vibrational coupling in plasmonic molecules
Abstract
Plasmon hybridization theory, inspired by molecular orbital theory, has been extremely successful in describing the near-field coupling in clusters of plasmonic nanoparticles, also known as plasmonic molecules. However, the vibrational modes of plasmonic molecules have been virtually unexplored. By designing precisely configured plasmonic molecules of varying complexity and probing them at the individual plasmonic molecule level, intramolecular coupling of acoustic modes, mediated by the underlying substrate, is observed. The strength of this coupling can be manipulated through the configuration of the plasmonic molecules. Surprisingly, classical continuum elastic theory fails to account for the experimental trends, which are well described by a simple coupled oscillator picture that assumes the vibrational coupling is mediated by coherent phonons with low energies. These findings provide a route to the systematic optical control of the gigahertz response of metallic nanostructures, opening the door to new optomechanical device strategies.
Copyright and License
© 2017. Published under the PNAS license.
Acknowledgement
This work was supported by Robert A. Welch Foundation Grants C-1222 (to P.N.), C-1220 (to N.J.H.), and C-1664 (to S.L.). P.N., N.J.H., and S.L. were supported by Army Grant MURI W911NF-12-1-0407 and Air Force Grant MURI FA9550-15-1-0022. S.L. was supported by National Science Foundation Grant ECCS-1608917. D.C. and J.E.S. were supported by the Australian Research Council (ARC) grants scheme and the ARC Centre of Excellence in Exciton Science.
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Additional details
Identifiers
- ISSN
- 1091-6490
- PMCID
- PMC5676925
Related works
- Is supplemented by
- https://www.pnas.org/doi/suppl/10.1073/pnas.1712418114/suppl_file/pnas.1712418114.sapp.pdf (URL)
Funding
- Welch Foundation
- C-1222
- Welch Foundation
- C-1220
- Welch Foundation
- C-1664
- Welch Foundation
- C-1787
- United States Army Research Office
- W911NF-12-1-0407
- United States Air Force Office of Scientific Research
- FA9550-15-1-0022
- National Science Foundation
- ECCS-1608917
- Australian Research Council