Simultaneous measurements of electronic conduction and Raman response in molecular junctions

TL;DR

This study demonstrates that simultaneous measurements of conductance and Raman spectra in molecular junctions reveal correlated fluctuations, enabling multimodal sensing of single molecules and providing insights into their electronic and structural properties.

Contribution

The paper introduces a method for concurrent measurement of conductance and Raman spectra in single-molecule junctions, revealing correlated dynamics and enabling multimodal molecular sensing.

Findings

Conductance and Raman signals fluctuate in tandem, indicating correlated molecular behavior.

Simultaneous measurements do not alter the Raman enhancement, confirmed by simulations.

Multimodal sensing of individual molecules is feasible in mass-producible nanostructures.

Abstract

Electronic conduction through single molecules is affected by the molecular electronic structure as well as by other information that is extremely difficult to assess, such as bonding geometry and chemical environment. The lack of an independent diagnostic technique has long hampered single-molecule conductance studies. We report simultaneous measurement of the conductance and the Raman spectra of nanoscale junctions used for single-molecule electronic experiments. Blinking and spectral diffusion in the Raman response of both para-mercaptoaniline and a fluorinated oligophenylyne ethynylene correlate in time with changes in the electronic conductance. Finite difference time domain calculations confirm that these correlations do not result from the conductance modifying the Raman enhancement. Therefore, these observations strongly imply that multimodal sensing of individual molecules is possible in these mass-producible nanostructures.