The Effect of Applied Potential on Plasmon Resonance Bands of Nanoscopic Silver Particles Adsorbed on Transparent Electrodes

The plasmon resonance spectra of nanoscopic silver particles adsorbed on transparent semiconductor electrodes in contact with eight aqueous electrolytes (KCl, KBr, KI, NaCl, NaBr, NaI, NaClO4, and KPF6) have been examined. In all electrolytes, the plasmon resonance bands are red-shifted and decreased in intensity as the applied potential is made more positive. The degree of the potential-induced spectral changes depends on the electrolyte type and concentration. The change in plasmon absorption band is largest for the higher concentration. At constant concentration, the potential-induced spectral changes are largest in the presence of I-, Cl- and Br- anions and smallest in the presence of PF6 -and ClO4 -anions. The largest effects for particles in contact with I-, Cl-and Br- anions may arise from more severe reduction in electron mean free lifetime and/or the formation of a metal-adsorbate complex which is highly absorbing in the spectral region of the plasmon resonance band.