Studies of the adsorption of a corrosion inhibitor onto mild steel using surface second-harmonic generation

Second-harmonic generation at surfaces has been demonstrated to be capable of following, in situ, the adsorption of a model corrosion inhibitor, oleic imidazoline (OI), [1-(2-aminoethyl)-2(heptadec-8-enyl)-2-imidazoline], onto a mild steel surface with submonolayer sensitivity. Comparative studies have been made with a short hydrocarbon tail OI variant together with orientation measurements. These indicate that the imidazoline group acts as a strong chemical anchor lying flat on the surface. The hydrocarbon tail in OI acts as a hydrophobic barrier inhibiting corrosion. Preliminary measurements on OI have also been performed in white oil where it is not possible to make confirming electrochemical measurements.