Optical probes of molecules as nano-mechanical switches.


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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.

Description
Keywords
3403 Macromolecular and Materials Chemistry, 34 Chemical Sciences, 40 Engineering, 51 Physical Sciences, 4018 Nanotechnology, Bioengineering, Nanotechnology, 7 Affordable and Clean Energy
Journal Title
Nat Commun
Conference Name
Journal ISSN
2041-1723
2041-1723
Volume Title
11
Publisher
Springer Science and Business Media LLC
Rights
All rights reserved
Sponsorship
EPSRC (1648373)
EPSRC (1648373)
Engineering and Physical Sciences Research Council (EP/G060649/1)
Engineering and Physical Sciences Research Council (EP/L027151/1)
Engineering and Physical Sciences Research Council (EP/G037221/1)
European Commission Horizon 2020 (H2020) Future and Emerging Technologies (FET) (829067)
Engineering and Physical Sciences Research Council (EP/L015978/1)
Engineering and Physical Sciences Research Council (EP/P029426/1)
Isaac Newton Trust (18.08(K))
Leverhulme Trust (ECF-2018-021)
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