SERS and DFT investigation on the adsorption of 1,10-phenanthroline on transition metal surfaces

SERS spectra of 1,10-phenanthroline (phen) on iron smooth surface doped with silver nanoparticles have been recorded and compared with those previously obtained on Ag doped smooth silver, copper and nickel surfaces. In order to correctly assign the SERS spectra, DFT/B3LYP calculations of phen and different models of phen/metal surface complexes have been performed. The 6-311++G(d, p) basis set was used for phen, whereas a mixed basis 6-311++G(d, p)/LANL2DZ was utilized in the case of the phen/metal complexes. From the comparison between the experimental and computational data, it was evidenced that phen was chemisorbed through its N atoms to the Ag, Cu, Ni and Fe surfaces, whereas the deposited Ag colloidal nanoparticles only played the role of providing the electromagnetic enhancement (with a factor of more than 10(3)) necessary to detect a suitable SERS signal.