Adsorption of 1,2,4-triazole on a silver electrode: surface-enhanced Raman spectroscopy and density functional theory studies

The pH-dependent surface-enhanced Raman scattering (SERS) of 1,2,4-triazole adsorbed on silver electrode and normal Raman (NR) spectra of this compound in the aqueous solutions were investigated. The observed bands in the NR and SERS spectra were assigned with the help of density functional theory calculations for model molecules in the neutral, anionic, and cationic forms and their complexes with silver. The Raman wavenumbers and intensities were computed at the optimized molecular geometry. Vibrational assignments of the SERS and NR spectra are provided by calculated potential energy distributions. The combination of experimental SERS results and density functional theory calculations provide an insight into the molecular structure of adlayers formed by 1,2,4-triazole on a silver surface at varying pH values and enable the determination of molecular orientation with respect to the surface. Copyright (c) 2012 John Wiley & Sons, Ltd.