Surface-enhanced Raman scattering of π-conjugated “push–pull” molecules: Part I. p-Nitroaniline adsorbed on silver nanoparticles

Surface enhanced Raman scattering (SERS) of p-nitroaniline is first obtained in silver hydrosol activated by coadsorption of chloride anions. The intensities of the SERS bands are interpreted in terms of charge-transfer enhancement mechanism, by considering the adsorbate in a quinonoid electronic structure. The SERS enhancement factor has been estimated by measuring the amount of ligand really adsorbed onto the silver nanoparticles and will be compared with those of non-linear properties.