“…S2 Supporting Information), with four methyl instead of two ethyl groups. Comparing the Raman bands observed for this sample and those reported in the literature for Nile Blue, only a partial correspondence is found with the FT-Raman spectrum of the historical reference sample discussed in [8] , while a more complete similarity is detected with the modern sample examined in [45] . In this scenario, interesting results were provided by SERS analysis: the main peaks in the spectrum ( Fig.…”