Detecting photoinduced electron transfer processes in the SERS spectrum of salicylate anion adsorbed on silver nanoparticles

The surface‐enhanced Raman scattering (SERS) of salicylic acid (S) adsorbed on a silver sol in H 2 O and D 2 O has been investigated. At pH 5 or greater, the adsorbed species is the salicylate anion (2‐hydroxybenzoate anion) (S − ), which links to the metal nanoparticle (Ag n ) through the carboxylate group (S − –Ag n ). We demonstrate that the selective enhancement of the bands is due mainly to a resonant electron or charge transfer process (ET or CT) from the metallic nanoparticle to the adsorbate, yielding the transient formation of the respective radical dianion (S· 2− –Ag n + ). It is found that the enhanced bands, and especially mode 8a;ν ring , are related to the differences between the equilibrium structures of the adsorbate in its ground (S − ) and CT‐excited states (S· 2− ). © 2006 Wiley Periodicals, Inc. Biopolymers 82: 379–383, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com