Fig. 5.
Absorption and scattering cross-sections of SPs in an NP ring. (A) Simulated absorption (magenta) and scattering (blue) spectra of the ring segment marked by the cyan rectangle in Fig. 1A. The experimental scattering spectrum (cyan) from Fig. 1A is also included for comparison. (B–D) Histograms of σABS obtained from 40 ring segments of the photothermal images for 785, 675, and 514 nm excitation, respectively. (E–G) Histograms of σSCA obtained from 24 ring segments of the scattering images measured with band pass filters of 800 ± 20, 700 ± 20, and 550 ± 20 nm, respectively. (H and I) Electromagnetic-field enhancements of the same NP ring segment at 785 and 514 nm, respectively.