| Figure: Spontaneous excitation of plasmonic resonant modes and
vertical cavity resonant modes in Ag nanocavity via CL spectroscopy
analysis. (a-e) CL spectra of nanocavities with 80, 150, 250,430,
and 550 nm heights, respectively. The numbers on the right side of
the figures indicate the diameters of the cavities in nm. The
spectra were obtained when the electron beam was incident near the
centers of the cavities. The plasmonic modes are classified and
indicated with blue dotted lines and characters, respectively.
Spectra are offset vertically for clarity. (f) Typical monochromatic
CL image at a resonant wavelength of 698 nm for a cavity with a 490
nm diameter. (g-i) Typical monochromatic CL images at resonant
wavelengths of 681, 528, and 501nmfor a cavity with a 765nmdiameter,
respectively. The red dashed circles show the boundaries of the
cavities. Scale bars are 500 nm. (j-m) Calculated intensity patterns
of the out-of-plane electric components for the plasmonic modes (0,
1), (1, 1), (2, 1), and (0, 2), respectively. (n, o) Dispersions of
plasmonic modes (0, 1) and (1, 1) in the nanocavities. The gray and
black lines respectively represent the dispersions of light in
vacuum and SPPs on an infinite Ag film.
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