Fig. 1
From: Probing of sub-picometer vertical differential resolutions using cavity plasmons
Cavity plasmons in a NWOM setup. a Schematic of the NWOM system—a metal nanowire is separated from a metal mirror by a thin film whose thickness change can be precisely probed. b High-resolution TEM cross-sectional image of a single NWOM system: a crystalline AuNW with a pentagonal cross section situated on an ultrasmooth gold film separated by a 1.5-nm-thick Al2O3 spacer. Further, a 8-nm-thick Al2O3 layer is coated on the surface of the NWOM to make the shape of the nanowire clear. Scale bar, 30 nm. c Calculated scattering spectrum of a 45-nm-diameter AuNW on the gold film with 2-nm vacuum separation, showing two resonant peaks corresponding to a transverse dipole mode (T) and the lowest frequency cavity-plasmon mode (M). d, e The surface charges (d) and the electric field (e) distributions of the M mode
