Fig. 3: The comparison between tandem in situ SEIRA (blue) and SER (green) spectra.

The spectra on a the same polycrystalline Au film and c two fresh OD-Cu films in CO saturated 0.1 M KHCO3 (pH 8.9) and 0.05 M K2CO3 (pH 10.6), respectively. The intensity of SEIRAS is scaled up in order to be plotted on the same scale as SERS. The dashed lines indicate the difference in peak frequencies between SEIRA and SER spectra under the same potential. The CO peak frequencies in SEIRA (blue) and SER (green) spectra on b Au film and d OD-Cu film as a function of electrode potential. The Stark tuning rates are determined by dashed lines and labeled in the figure.