Graphene Enhanced Raman Scattering effect of RhB adsorbed on graphene oxide thin films by spectral mapping deconvolution

Graphene Enhanced Raman Scattering (GERS) of adsorbed organic molecules on graphene oxide (GO) substrates is associated to a chemical enhancing mechanism. Several works reported relative intensity variations of Raman signatures of organic molecules depending on the GO thickness or the degree of reduction. In this work, we get further insight in GERS effect through spectra deconvolution of Raman mappings of Rhodamine B (RhB) adsorbed on GO. Aqueous/ethanol solution of synthetized GO was deposited on hydrophilic Si/SiO₂ substrates by spin coating. Simultaneous noncontact AFM and Raman mapping studies were performed in areas around 20 μm². AFM shows uniform GO films with 5 nm thickness and 1.27 nm roughness. By means of spectra Raman deconvolution we got maps of intensity, width and central position of G and D bands of GO. RhB molecules were adsorbed by immersion in an aqueous solution. In the GO-RhB sample, AFM shows no presence of adsorbed molecules, however Raman mapping allows to discriminate areas with different amount of RhB fluorescence suppression and Raman enhancing. We identify several RhB Raman bands overlapping with the GO ones. We performed a detailed spectral deconvolution and maps of intensity, width and central position shift of different Raman bands are reported.