A SERS investigation of the electrodeposition of Ag–Au alloys from free-cyanide solutions – part II

Some aspects of the in situ SERS behaviour of free cyanide containing Ag, Au and Ag–Au solutions during electrodeposition are reported in this paper. The basic spectroelectrochemical phenomenology has been treated in a companion paper [J. Electroanal. Chem. 563 (2004) 133] and discussed in relation to electrochemical (cyclic voltammetry and potentiostatic electrodeposition), structural (X-ray diffraction), morphological (scanning electron microscopy) and compositional (energy dispersive spectroscopy) results. In the present work we evaluated and discussed the Stark-tuning of the surface CN− stretching band. The non-linear Stark-tuning of the cyanide-stretching band was correlated to the covalent vs. ionic character of the cyanide–metal adsorption bond and to the pzc of the specific systems. In addition, we stressed the peculiarities of the highly negative potential range, in which remarkable changes in the spectral patterns occur and fluorescence sets in.