Figure 4: Suppressing the PSSE to retrieve the intrinsic relative intensity of the Raman speaks.

(a) SERS^raw spectra from Fig. 3a–e, corresponding to five nanorods of different aspect ratio before background subtraction, plotted here in a single graph for simpler comparison. (b) SERS^sub spectra obtained after subtracting the fitted SERS background Bg to the spectra in a. (c–e) Spectra obtained by normalizing each of the five SERS^sub spectra in b. In c a normalization by the corresponding elastic scattering spectrum of each nanorod (dotted lines in Fig. 3f) is used to obtain SERS^sub/S. (d) SERS^sub × PL_bulk/Bg, obtained by dividing each background-subtracted SERS spectrum by the corresponding fitted SERS background and then multiplying each spectrum by the PL_bulk signal in the bottom right panel in Fig. 2c. (e) SERS^sub/Bg ratio, obtained after normalization by the SERS background. For comparison, the normal Raman spectrum of MGITC on a gold (111) single-crystal surface is shown at the bottom (blue line) of b–e. All the spectra in c–e, have been further normalized by the corresponding SERS^sub peak at 683.8 nm (corresponding to 1,173.3 cm⁻¹ in Raman shift).