Scanning tunneling microscopy of copper corrosion in aqueous perchloric acid

Copper has been imaged with scanning tunneling microscopy (STM) during immersion in aqueous HCIO4 solutions of different concentrations. STM images were recorded continuously to follow the dynamic processes of the surface. The images indicate that the surface changes become more pronounced with increasing acid concentration. The surface change is predominantly due to copper dissolution. The local corrosion rate estimated from the STM images has been compared with those obtained from SEM micrographs and found to be in satisfactory agreement.