Fig. 2

Antenna effect and plasmon characteristics of silver and gold TERS tips. a Incidence of p-polarised laser (k indicates the wave vector of the excitation laser) with electric field (E) parallel to the tip-axis at a metal or metal-coated tip causes the EM field intensity to be enhanced and confined at the tip-apex. Red colour represents a higher intensity of EM field. This image is calculated using COMSOL Multiphysics®. Tip radius: 15 nm. b Scattering of light from silver- and gold-coated silicon AFM tips. Figure (b) is reproduced by permission of IOP Publishing from reference [26]. Copyright 2013 IOP Publishing. All rights reserved