Figure 3: Subnanometre gaps formed in metallic structures.
From: Quantum mechanical effects in plasmonic structures with subnanometre gaps
(a) Schematic illustration of the plasmonic dimer formed by pushing two AFM cantilevers in tip-to-tip configuration. Reproduced from ref. 67. Copyright 2012 Nature Publishing Group. (b) High-resolution TEM images of Ag nanosphere dimer formed by pushing two Ag nanoparticles together using focused electron beam. The diameter of each Ag nanoparticle is 9 nm. Top panel: overview of the dimer. Scale bar is 5 nm. Bottom panel: Zoomed-in view of the Ag dimer showing the gap distance d≈3.5 Å. Scale bar is 2 nm. Reprinted with permission from ref. 68. Copyright 2013 American Chemical Society. (c) TEM image of Au nanodisk dimer form by two-step electron beam lithography. The diameter of each nanodisk is 90 nm. Top panel: overview of the dimer. Scale bar is 50 nm. Bottom panel: zoomed-in view of the Au dimer showing the gap distance d≈2.0 Å. Scale bar is 2 nm. Reproduced from ref. 70. Copyright 2014 Nature Publishing Group. (d) High-resolution TEM image of the Ag dimer formed by linking molecules, with zoomed-in TEM image showing the subnanometre gap distance. Image reproduced from ref. 97. Copyright 2014 AAAS. (e) Schematic of particle-on-film geometry, with the nanoscale gap defined by a thin self-assembled monolayer layer. Image reproduced from ref. 32. Copyright 2012 AAAS.
