New opportunities for the study of organic films applied on metals for corrosion protection by means of alternating current scanning electrochemical microscopy

► Alternating current scanning electrochemical microscopy is used to study corrosion inhibition. ► Approach curves show a transition from positive to negative feedback at a characteristic frequency. ► The value characteristic frequency is a measure of the protecting efficiency of inhibitor films. ► The new method is applied to the corrosion inhibition of copper by four model inhibitors.