Electrical and SERS detection of disulfide-mediated dimerization in single-molecule benzene-1,4-dithiol junctions

Abstract

We applied a combination of mechanically controllable break junction (MCBJ) and <i>in situ</i> surface enhanced Raman spectroscopy (SERS) methods to investigate the long-standing single-molecule conductance discrepancy of prototypical benzene-1,4-dithiol (<b>BDT</b>) junctions. Single-molecule conductance characterization, together with configuration analysis of the molecular junction, suggested that disulfide-mediated dimerization of <b>BDT</b> contributed to the low conductance feature, which was further verified by the detection of S-S bond formation through <i>in situ</i> SERS characterization. Control experiments demonstrated that the disulfide-mediated dimerization could be tuned <i>via</i> the chemical inhibitor. Our findings suggest that a combined electrical and SERS method is capable of probing chemical reactions at the single-molecule level.