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Kos D, Di Martino G, Boehmke A, de Nijs B, Berta D, Földes T, Sangtarash S, Rosta E, Sadeghi H, Baumberg JJ. Optical probes of molecules as nano-mechanical switches. Nat Commun 2020; 11:5905. [PMID: 33219231 PMCID: PMC7679449 DOI: 10.1038/s41467-020-19703-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 10/26/2020] [Indexed: 11/14/2022] Open
Abstract
Molecular electronics promises a new generation of ultralow-energy information technologies, based around functional molecular junctions. Here, we report optical probing that exploits a gold nanoparticle in a plasmonic nanocavity geometry used as one terminal of a well-defined molecular junction, deposited as a self-assembled molecular monolayer on flat gold. A conductive transparent cantilever electrically contacts individual nanoparticles while maintaining optical access to the molecular junction. Optical readout of molecular structure in the junction reveals ultralow-energy switching of ∼50 zJ, from a nano-electromechanical torsion spring at the single molecule level. Real-time Raman measurements show these electronic device characteristics are directly affected by this molecular torsion, which can be explained using a simple circuit model based on junction capacitances, confirmed by density functional theory calculations. This nanomechanical degree of freedom is normally invisible and ignored in electrical transport measurements but is vital to the design and exploitation of molecules as quantum-coherent electronic nanodevices. The development of molecular electronics at single molecule level calls for new tools beyond electrical characterisation. Kos et al. show an optical probe of molecular junctions in a plasmonic nanocavity geometry, which supports in situ interrogation of molecular configurations.
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Affiliation(s)
- Dean Kos
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Giuliana Di Martino
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
| | - Alexandra Boehmke
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Bart de Nijs
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Dénes Berta
- Department of Chemistry, King's College London, London, SE1 1DB, UK
| | - Tamás Földes
- Department of Chemistry, King's College London, London, SE1 1DB, UK
| | - Sara Sangtarash
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK
| | - Edina Rosta
- Department of Physics and Astronomy, University College London, London, WC1E 6BT, UK.
| | - Hatef Sadeghi
- School of Engineering, University of Warwick, Coventry, CV4 7AL, UK.
| | - Jeremy J Baumberg
- NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
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