Fig. 5
From: Plasmonic sensors based on graphene and graphene hybrid materials
Roles of graphene in graphene-based plasmonic materials. a Optical images of Cu and Cu/Ni foil with and without graphene coating taken before and after annealing in air (200 °C, 4 h). Reprinted with permission from [84]. Copyright 2011 American Chemical Society. b Raman spectra of R6G on graphene hybrid structure with 3 different concentrations (10− 10 M, 10− 12 M, and 10− 14 M) and Raman spectra of R6G on Au tips with 3 different concentrations. Reproduced with permission from [71] Copyright 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. c Graphene as a gap material enabling the thickness control with the sub-nanometer scale precision: comparison between the experimental (black) and computed (red) optical responses for samples excited by a 633 nm laser and a 785 nm laser. The left vertical axis represents the peak Raman intensity measured from a solution of brilliant cresyl blue molecules. The different layer number of graphene gap significantly changes the Raman enhancement of the whole hybrid system. Reprinted under the terms of the Creative Commons License from [94]. Copyright 2019 The Authors. Published by Springer Nature