Fig. 2.

Molecular influence on hot charge carrier transport. a Chemical structures of six different molecular tunnelling junctions (MTJ: I-VI) used in the hot-electron reduction experiments, sorted by expected tunnelling mechanism. b SERS time scans from individual NPoM geometries (normalised), with MTJs I-VI, changing the expected electron transport mechanism from coherent tunnelling to hopping (0.1 s integration time taken over 70 s, raw spectra available in Supplementary Fig. 3). c Calculated coherent electron transmission spectra for I-IV. d, Experimentally observed vibrational frequency fluctuations in time for each MTJ. e Histograms for each MTJ depicting the occurrence of peaks at each vibrational frequency, grey indicating the unperturbed states, with V and VI compared to theory (below) where dark grey is exp., red depicts the normalised Raman cross-section calculated for the 2 + state (ground state for VI), purple: 1 + (ground state for V) and blue: neutral