Figure 2: Modelling of plasmonic dimers with subnanometre gap.
From: Quantum mechanical effects in plasmonic structures with subnanometre gaps
(a–f) Comparison of the optical properties of a metallic dimer simulated with (a,b) local Drude model, (c,d) TDDFT calculation and (e,f) the QCM. The dimer consists of two Na spheres with radii of 2.17 nm. (a,c,e) The colour plots of the extinction spectra σext as a function of gap distances. (b,d,f) The simulated near-field enhancements as a function of gap distances. The relevant plasmon modes are labelled: bonding dimer plasmon (BDP), bonding quadrupolar plasmon (BQP), charge transfer plasmon (CTP) and higher-order charge transfer plasmon (CTP’). (a–f) Images are reproduced from ref. 64. Copyright 2014 Nature Publishing Group. (g–j) Simulations of nonlocal effects for a metallic bowtie dimer. The dimer consists of two Au wires with cross-sections comprising equilateral triangles (side length: 45 nm, gap distance: 1 nm, tip radius of curvature: 1 nm). (g) Extinction cross-section spectra σext and (h) the near-field enhancement <γ> calculated from the local classical model (red dashed lines) and the NLHD model (blue solid lines). (i,j) Near-field distribution around the gap region of the Au bow-tie dimer calculated from (i) the local classical model and (j) the NLHD model. The colour scales in i,j represent the enhancement of the electric near-field. (g–j) Figures adapted with permission from ref. 86.
