Electron Transport Across Plasmonic Molecular Nanogaps Interrogated with Surface-Enhanced Raman Scattering

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Li Lin
  • Qiang Zhang
  • Xiyao Li
  • Meng Qiu
  • Xin Jiang
  • Wei Jin
  • Hongchen Gu
  • Jian Ye

Detail(s)

Original languageEnglish
Pages (from-to)6492-6503
Journal / PublicationACS Nano
Volume12
Issue number7
Online published20 Jun 2018
Publication statusPublished - 24 Jul 2018
Externally publishedYes

Abstract

Charge transport plays an important role in defining both far-field and near-field optical response of a plasmonic nanostructure with an ultrasmall built-in nanogap. As the gap size of a gold core-shell nanomatryoshka approaches the sub-nanometer length scale, charge transport may occur and strongly alter the near-field enhancement within the molecule-filled nanogap. In this work, we utilize ultrasensitive surface-enhanced Raman spectroscopy (SERS) to investigate the plasmonic near-field variation induced by the molecular junction conductance-assisted electron transport in gold nanomatryoshkas, termed gap-enhanced Raman tags (GERTs). The GERTs, with interior gaps from 0.7 to 2 nm, are prepared with a wet chemistry method. Our experimental and theoretical studies suggest that the electron transport through the molecular junction influences both far-field and near-field optical properties of the GERTs. In the far-field extinction response, the low-energy gap mode predicted by a classical electromagnetic model (CEM) is strongly quenched and hence unobservable in the experiment, which can be well explained by a quantum-corrected model (QCM). In the near-field SERS response, the optimal gap size for maximum Raman enhancement at the excitation wavelength of 785 nm (633 nm) is about 1.35 nm (1.8 nm). Similarly, these near-field results do not tally with the CEM calculations but agree well with the QCM results where the molecular junction conductance in the nanogap is fully considered. Our study may improve understanding of charge-transport phenomena in ultrasmall plasmonic molecular nanogaps and promote the further development of molecular electronics-based plasmonic nanodevices.

Research Area(s)

  • charge transfer, electron transport, gap-enhanced Raman tags, molecule junction conductance, quantum plasmonics

Citation Format(s)

Electron Transport Across Plasmonic Molecular Nanogaps Interrogated with Surface-Enhanced Raman Scattering. / Lin, Li; Zhang, Qiang; Li, Xiyao et al.

In: ACS Nano, Vol. 12, No. 7, 24.07.2018, p. 6492-6503.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review