Fig. 3: Plasmon dispersion.
From: Real-space imaging of acoustic plasmons in large-area graphene grown by chemical vapor deposition
a AGP dispersion obtained from the interference fringes in near-field at the sample with t = 21 nm (circles), and the analytically calculated dispersion for EF = –0.46 eV: the exact solutions for AGP (red solid), GSP (red dashed; for thick alumina layer), and the imaginary part of the reflection coefficient (color map). b Top row: distribution of the near-field contrast \(\left| {\eta (x,y)} \right|\) over the same graphene edge obtained at different excitation frequencies. Bottom row: corresponding \(\left| \eta \right|\) profiles across the graphene edge, measured along the dashed line (average value for ten-pixel-wide lines). c Spectral dependency of the calculated De (solid) and the measured \(\left| \eta \right|\) above the sample shown in (b) (circles; averaged over the area far from the edge).
