Spectroscopic Characterization of Iridescent Chromium Films Obtained by Pulsating Electrodeposition

The structures and constituents of both electrodeposited pink and light-green chromium films from oxalic acid with spuare pulsating current superposed direct current are characterized by means of XPS, UV and IR diffuse reflection spectroscopies. The XPS analysis shows that these chromium films consist of three layers, i.e., interracial layer (Cr₂O₃, Cr and Ni), intermediate layer (Cr₂O₃, also containing some water) ang surface layer (Cr(Ⅵ), Cr(Ⅲ)). The color and properties of the films are mainly determined by the intermediate layer. The presence of hydrate water and free-water modifies the ligand field of central ion Cr(Ⅲ), so that the absorption bands of iridescent chromium films are influenced.