We have systematically studied the adsorption of thiocyanate (SCN-) on gold-core palladium-shell nano-particles (Au@Pd NPs) with different Pd shell thicknesses by surface-enhanced Raman scattering (SERS). When the Pd shell thickness is increased from one to ten atomic layers, the v(C-N) stretching frequency increases 6 cm(-1) for S-bound SCN- and 10 cm(-1) for N-bound SCN-. It infers that the v(C-N) stretching frequency is quite sensitive to electronic properties of the NP surface, but even more so when bonding to Pd occurs through the N atom (at negative potentials) than when it occurs through the S atom (at positive potentials). Data for a second probe, p-aminothiophenol (PATP), was compared to that of SCN-; however, PATP was found to be less sensitive than SCN- to the surface electronic properties of Au@Pd NPs. (C) 2011 Elsevier B.V. All rights reserved. ; NSFC [20620130427]; MOST [2007DFC 40440]; National Basic Research Program of China [2009CB930703, 2007CB815303]