Tapping mode atomic force microscopy observation of self-affine fractal roughness in electrochemically roughened silver electrode surfaces

Abstract

We have investigated recrystallization of an electrochemically roughened silver electrode surface in Ar-saturated water, using cyclic voltammetry (CV), Auger electron spectroscopy (AES), and tapping mode atomic force microscopy (TMAFM). Comparison of CVs before and after 92 h relaxation in water indicates that surface flattening occurs at room temperature when the roughened Ag is in contact with water. An AES spectrum of the Ag surface before the relaxation shows that chlorine still remains on the surface, probably in the form of AgCl. We determined the roughness exponents (α) for the roughened Ag surfaces before and after the relaxation from the slopes of the linear regions observed in plots of log (the interface width) vs log (length scale) calculated from TMAFM data. At larger length scales than the average Ag nodule size, αs were 0.50±0.02 and 0.64±0.02 for the roughened surfaces before and after the relaxation, respectively. These results suggest that the scaling theory may be applicable to the recrystallization process at the submicron level.