An in situ Raman investigation of organic species incorporated in Cu layers electrodeposited from PEG-containing acidic sulphate and cyanalkaline electrolytes

In situ surface Raman spectroscopy was used to detect organic species embedded in Cu electrodeposits obtained from cyanoalkaline and acidic sulphate solutions containing polyethylene glycol (PEG). These measurements rely on the release of the organic species at the surface of the electrode during controlled corrosion in pure acidic aqueous solutions and on the development of surface-enhancing morphological elements in the course of the anodic dissolution. After an induction period, well defined vibrational bands appear, assigned to vinyl and hydroxyl groups that can result from cleavage reactions of the PEG chain. This technique is shown to be robust and to exhibit negligible dependence on details of the corrosion process (either galvanostatic of potentiostatic) or of the environment (0.5 M H2SO4 or HCl).