The surface and cross-sectional morphology of the anodized samples were determined by using scanning electron microscopy (SEM) (Quanta FEG 250 FEI) at low vacuum and 30 kV accelerating voltage. The cross-section image was obtained by the cutting anodized foil through the middle to expose the edge of the anodized area and imaging this edge by using a sample holder at 90 ͦ tilt. Energy dispersive X-ray spectroscopy (EDS) at 30 kV which is coupled to the SEM was used to determine the elemental composition of the samples. X-ray photoelectron spectroscopy (XPS/ESCA; SSX-100 S-probe) which also gives information about the surface chemical component was performed with monochromatized Al Kα radiation, and the core level binding energies were normalized using the adventitious C 1s peak set at 284.8 eV. Time of flight secondary ion mass spectrometry (ToF -SIMS) which also provides surface chemical information was done. Positive and negative static SIMS spectra were recorded (ToF -SIMS 4, IONTOF GmbH) using a 25 keV Bi + ion beam bunched down to <0.8 ns.