Figure 1: Coupling LH2 to a gold nanoantennas in an ensemble measurement.

(a) Schematic presentation of a gold NR with an LH2 complex located in the antenna hot spot. (b) The absorption and emission spectra of LH2 in solution, and the extinction spectra of L=120, 160 and 200 nm NRs. The extinction spectra were measured with the polarization of the incident light parallel to the long antenna axis. (c) Schematic presentation of the NR array with increasing antenna length. The polarization of the excitation light is parallel to the NRs. (d) Extinction of the antennas at the excitation (λ=800 nm) and emission (λ=870 nm) wavelength as a function of antenna length. (e) Confocal fluorescence image of LH2 in PVA spin-coated over NRs with length increasing from L=110–220 nm. The intensity is normalized to the unenhanced emission coming from ~\n800 LH2s in our diffraction limited focus. Scale bar, 10 μm. (f) Average fluorescence enhancement. The maximal enhancement is reached for L=160 nm Au NRs. Inset: histogram of the enhancement for 54 Au NRs of L=110, 160 and 220 nm.