Applied Physics

Glimpsing Tiny Live Wires

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Science  29 Feb 2008:
Vol. 319, Issue 5867, pp. 1162
DOI: 10.1126/science.319.5867.1162c

The realization of molecular electronics requires reproducible methods for creating devices in which conduction occurs through individual molecules. Current methods rely on the fabrication of many devices to prove statistically that a single-molecule junction has been realized, but knowledge of the specific chemical environment of the conducting molecules tends to be limited, complicating the interpretation of the data. Ward et al. present a method for simultaneous electron transport measurements and single-molecule sensing using surface-enhanced Raman spectroscopy (SERS) on nanometer-scale structures (nanogaps) bridged by individual molecules. The metal electrodes that are used as contacts to the molecules also function as plasmonic antennae, resulting in an enormously enhanced vibrational signal. In about 1 in 10 junctions, changes in conductance with time correlate closely with changes in the SERS signal, supporting a link between electron transport and single-molecule conformational changes. The relation between conductance and SERS spectra remains complex, but steadily improving theoretical analyses paired with such measurements should shed light on the fundamental mechanisms at play. — JFU

Nano Lett. 8, 10.1021/nl073346h (2008).

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