Gap Nanoantennas toward Molecular Plasmonic Devices

Figure 10

(a) Fluorescence image of perylene fluorescent molecules spin-coated on a substrate with dimer and monomer nanoantennas. (b) Fluorescence intensity trajectory measured at the position is indicated with circle numbered 1 in (a). Red and green trajectories indicate signals with orthogonal in-plane polarizations, while the black line indicates the total intensity. The intensity trajectory at position (1) shows a clear multilevel intensity blinking and bleaching reminiscent of molecular fluorescence. (c) Zoom in to the first 20 s where the four intensity levels are indicated with dashed blue lines. (d) The intensity trajectory measured at position number 2 in (a) displays similar blinking. (e) The fluorescence spectrum is recorded in the initial 7.5 s of the trajectory at position 2, with the spectra measured between 𝑡=30 and 𝑡=60 s subtracted. The resulting spectrum is a typical emission spectrum of our perylene molecule. (f) Fluorescence lifetime is measured at position 2. Dashed lines in the lifetime graph indicate exponential fits with lifetimes of 𝜏₁=0.4 ns and 𝜏₂=5 ns, respectively.