Anomalously large spectral shifts near the quantum tunnelling limit in plasmonic rulers with subatomic resolution

Charlie Readman, Bart De Nijs, Istvan Szabo, Angela Demetriadou, Ryan Greenhalgh, Colm Durkan, Edina Rosta, Oren A. Scherman, Jeremy J. Baumberg

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)
176 Downloads (Pure)

Abstract

The resonance wavelength of a coupled plasmonic system is extremely sensitive to the distance between its metallic surfaces, resulting in “plasmon rulers”. We explore this behavior in the subnanometer regime using self-assembled monolayers of bisphthalocyanine molecules in a nanoparticle-on-mirror (NPoM) construct. These allow unprecedented subangstrom control over spacer thickness via choice of metal center, in a gap-size regime at the quantum-mechanical limit of plasmonic enhancement. A dramatic shift in the coupled plasmon resonance is observed as the gap size is varied from 0.39 to 0.41 nm. Existing theoretical models are unable to account for the observed spectral tuning, which requires inclusion of the quantum-classical interface, emphasizing the need for new treatments of light at the subnanoscale
Original languageEnglish
Pages (from-to)2051-2058
Number of pages8
JournalNano Letters
Volume19
Issue number3
Early online date6 Feb 2019
DOIs
Publication statusPublished - 13 Mar 2019

Keywords

  • DFT
  • Nanocavities
  • SERS
  • nanoassembly
  • phthalocyanines
  • quantum plasmonics

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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