Fig. 4: Molecular photo-induced spectral shifts in NPoMs.
From: Extensive photochemical restructuring of molecule-metal surfaces under room light
a DF scattering spectra of 2,2′-BPD in NPoM gap evolving over \(t\)=0-30 h under 0.1 W cm−2, colour gradient from dark blue (start) to light yellow (end) gives time progression. b Simulation of NPoM scattering using BEM model, for nanoparticle facet \(w\) increasing from 12 to 50 nm. c Spectral shift of coupled plasmon peak \(\Delta {\lambda }_{{{{{{\rm{c}}}}}}}\) versus time for seven different molecules: BPD, BPT, MBP, BDMT, BDT, BPDT in NPoMs, as well as for BPD with Pd-coated Au, and with Ni2+ pre-treatment. d, e Observed (d) maximum \(\Delta {\lambda }_{{{{{{\rm{c}}}}}}}\) and (e) rate \({\dot{\lambda }}_{{{{{{\rm{c}}}}}}}\), in increasing rank. f Experimental SERS spectra (solid) and DFT Raman simulations (dashed) of BPD SAM in NPoM before (brown) and after (black) 30 h illumination at 0.1 W cm−2. DFT uses one (brown dashed) or two (black dashed) thiol-Au terminations of BPD molecule. The grey dashed line marks the shifting bipyridine peak.
