Fig. 2: Representative dark-field scattering phenomena of the individual Ag nanorods.

a Dark-field scattering spectra measured from five Ag nanorods showing the red-blue-red patterns. The two vertical bars indicate the bandpass colour filters. The plasmon peaks at ~500 nm arise from the longitudinal octupolar plasmon mode (N = 3). The plasmon peaks at ~650 nm arise from the longitudinal quadrupolar plasmon mode (N = 2). b Dark-field scattering images of the five Ag nanorods shown in a. The images were recorded in the absence of a colour filter (left column), with the 500-nm bandpass filter (middle column) and the 600-nm bandpass filter (right column) inserted in front of the colour camera. c Dark-field scattering spectra measured from five Ag nanorods showing the green-red-green patterns. The two vertical bars indicate the bandpass colour filters. The plasmon peaks at ~550 nm arise from the longitudinal hexadecapolar plasmon mode (N = 4). The plasmon peaks at ~700 nm arise from the longitudinal octupolar plasmon mode (N = 3). d Dark-field scattering images of the five Ag nanorods shown in (c). The images were measured in the absence of a colour filter (left column), with the 550-nm bandpass filter (middle column) and the 700-nm bandpass filter (right column) inserted in front of the colour camera. The Ag nanorod samples were deposited on cover glass for the optical measurements