Research data supporting 'Tracking Interfacial Single-molecule pH and Binding Dynamics via Vibrational Spectroscopy' DOI: DOI: 10.1126/sciadv.abg1790

Figure 1B: Time-averaged SERS spectra of the MPA monolayer collected from SPARK, Nanoparticle-on-mirror (NPoM), and Nanocube-on-mirror (NCoM) nanocavities with, respectively, using 20-μW, 500-μW, and 1.2-mW optical excitation at 633 nm (300 s integration time), together with simulated Raman spectrum for monodentate MPA using polarized DFT calculations.

Figure 2: (A) SPARK SERS time series showing single-molecule dynamics of MPA, with 50-ms integration time per spectrum. (B) Pure state experimental spectra (deprotonated, protonated, and monodentate) extracted from SERS time scan. (G) Time evolution of the extracted fractional weights for the three pure states, revealing dynamic switching behavior. DFT spectra are generated through files in the Supplementary Information of the publication.

Figure 3: (A) SPARK SERS time series showing single molecular dynamics of MPA salt, with 100-ms integration time. (B) Pure state spectra extracted from the SERS time scan. (G) Full time evolution of a single MPA molecule hopping between three coordination states: unbound, monodentate, and bidentate.

Figure 4: (C) Extracted effective single-molecule pH fluctuation showing deprotonation is increasingly favored in time (pKa =4.3). (D) Variation of equilibrium energies of the monodentate (blue) and bidentate (green) states versus the unbound state extracted from the transition kinetics of the MPA salt. (E) Distributions of dwell times in the unbound (UB), monodentate (MD), and bidentate (BD) states of an MPA salt picocavity before hopping to a neighbor state.