Fig. 1.
Correlated SEM and Raman micrographs showing assemblies of Ag octahedral nanocrystals (A and B). Dimers and trimers coated with 4-AMT exhibited large SERS signals compared with a monomer (arrow). (C) SSEF values (λex = 633 and 785 nm) for different dimer assemblies: E-E (n = 10), F-F (n = 10), T-T (n = 4), and ncF-F (n = 10). (D and E) TEM images of nanocube and octahedra dimers show nanoscale interparticle gaps. (F) Aberration-corrected TEM image of the gap between two atomically smooth (100) facets of a nanocube dimer. A line profile of F shows the characteristic 0.29 nm spacing between Ag(100) atoms and a gap of 1.3 nm. (G) TEM gap data for two different nanocube dimers (a = 72 nm, n = 8 red circles; a = 122 nm, n = 10, blue squares) and octahedra dimers (a = 300, n = 3, green triangles). The average interparticle gap was 1.3–1.4 nm (black markers) with a SD of ∼0.1–0.2 nm.