Supplementary Information Strong coupling of localized plasmons and molecular excitons in nanostructured silver films N. I. Cade, T. Ritman-Meer, and D. Richards AFM analysis: A Veeco Explorer atomic force microscope (AFM) was used to characterize each film. Figure S1: AFM scans of regions of different nominal Ag film thickness. Each image is 1.3 1.3 m with a height scale of 6 nm. S1 SERS enhancement: Figure S2: Raman spectra from R6G on Ag films for a range of nominal thicknesses, exciting at A) 514nm and B) 647 nm. All spectra are uncorrected. Dashed lines give the spectra from R6G on glass. S2