Figure 3

(a) Normalized transmittance spectrum of a submicron-thick BSA protein layer (black circles), which was measured before the experiments; the signal strength shows a transmittance of approximately 25%. The spectrum was plotted with the transmittance of the MM sample (red circles) to show the matching of the protein signal and MM resonance. Red line shows the Fano fit for the signal of the submicron-thick BSA. (b) Normalized transmittance spectra of an ultrathin layer of BSA molecules absorbed on the MM sample and a reference sapphire substrate. (c) Spectra of the organic molecules DTTCI and Rh6G measured in conditions similar to those used for the BSA sample. For details, see the text.