SERS INVESTIGATION OF DISSOLUTION OF GOLD IN CYANIDE

Abstract: SERS provides an excellent in-situ method of observing in real-time the vibrational characteristics of surface species during electrochemically controlled gold dissolution in cyanide solution. The SERS technique allows rapid acquisition of spectra during voltammetric scans, allowing vi-brational characteristics of surface and solution species to be observed in real-time during electro-chemical events. Potential dependent SERS scans show a variation of vibrational frequency with potential, known as Stark-tuning. This phenomenon provides qualitative information regarding the nature of the chemical bonding and orientation of the surface species. A significant variation of Raman back-ground intensity is also seen during the acquisition of potentiodynamic SERS spectra. Elucidation of relationships between the Raman background and optical properties of the adsorbate-modified gold surface may facilitate the development of a novel surface-sensitive technique. Cyclic voltammetry in pH 11 buffered 0.01 mol dm-3 NaCN solutions show a solution cyanide species Stark-tuning linearly at 55 cm-1V-1 with νCN ranging from 2075 cm-1 at-1.4 V, to 2105 cm-1. Adsorption is evidenced at the onset of cyanidation,-0.8 V, by the appearance of low frequenc