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;nu(ring), are related to the differences between the equilibrium structures of the adsorbate in its ground (S(-)) and CT-excited states (S.(2-)).
Castro
J L
JL
Department of Physical Chemistry, University of Málaga, E-29071 Málaga, Spain.
Arenas
J F
JF
López-Ramírez
M R
MR
Otero
J C
JC
D000327:Adsorption; D004579:Electron Transport; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D012459:Salicylates / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*
D012459:Salicylates; D012834:Silver