Particle Size-Dependent Onset of theTunneling Regime in Ideal Dimers of Gold Nanospheres

Jesil Jose, Ludmilla Schumacher, Mandana Jalali*, Georg Haberfehlner, Daniel Erni*, Jan Taro Svejda, Sebastian Schlücker*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We report on the nanoparticle-size-dependent onset of quantum tunneling of electrons across the subnanometer gaps in three different sizes (30, 50, and 80 nm) of highly uniform gold nanosphere (AuNS) dimers. For precision plasmonics, the gap distance is systematically controlled at the level of single C−C bonds via a series of alkanedithiol linkers (C2−C16). Parallax-corrected high-resolution transmission electron microscope (HRTEM) imaging and subsequent tomographic reconstruction are employed to resolve the nm to subnm interparticle gap distances in AuNS dimers. Single-particle scattering experiments on three different sizes of AuNS dimers reveal that for the larger dimers the onset of quantum tunneling regime occurs at larger gap distances: 0.96 ± 0.04 nm (C6) for 80 nm, 0.83 ± 0.03 nm (C5) for 50 nm, and 0.72 ± 0.02 nm (C4) for 30 nm
dimers. 2D nonlocal and quantum-corrected model (QCM) calculations
qualitatively explain the physical origin for this experimental observation:
the lower curvature of the larger particles leads to a higher tunneling current due to a larger effective conductivity volume in the gap. Our results have possible implications in scenarios where precise geometrical control over plasmonic properties is crucial such as in hybrid (molecule-metal) and/or quantum plasmonic devices. More importantly, this study constitutes the closest experimental results to the theory for a 3D sphere dimer system and offers a reference data set for comparison with theory/simulations.
Original languageEnglish
Pages (from-to)21377–21387
Number of pages11
JournalACS Nano
Issue number12
Publication statusPublished - 27 Dec 2022


  • dark-field spectroscopy
  • gold nanospheres
  • HRTEM tomography
  • ideal dimers
  • plasmonics
  • quantum tunneling

ASJC Scopus subject areas

  • General Materials Science
  • General Engineering
  • General Physics and Astronomy
  • General Materials Science

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)

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