In situ spectroscopic ellipsometry during electrochemical treatment of zinc in alkaline carbonate electrolyte

► Thickness determination from ellipsometry without optical model ► ZnO thickness increases linearly with potential in the “pseudo-passive” regime. ► Density of interfacial layer in constant during potential increase ► Potentiostatic treatment shows an aging of the interfacial layer to yield ZnO. ► Absorption spectrum of the oxide is modified by metal transport.