*2.4. Surface Analysis*

The surface of the samples, prepared as described above, were analyzed in the presence and absence of 1.0 g L−<sup>1</sup> of GA. After the immersion, the samples were removed and rinsed with deionized water and dried. The surface analysis was carried out by means of different techniques such as a scanning electron microscopy combined with an energy dispersive spectroscopy, grazing incidence X-ray diffraction (GIXRD), and an X-ray photoelectron spectroscopy (XPS). The SEM measurements were carried out by using a JEOL scanning electron microscope. The GIXRD analysis was carried out to further determine the composition of the corrosion products film. Grazing incident X-ray diffraction (GIXRD) with an incident angle of 3◦ was applied to study samples phase composition. A Panalytical Empyrean X-ray diffractometer in the parallel beam geometry (Goebel mirror in the incident beam optics and parallel plate collimator in the secondary beam optics) with Co lamp (Kα = 1.7902 Å) was used to perform measurements. The samples were scanned with a 0.02◦ step in the range of 20◦– 70◦ at room temperature. The XPS analysis was carried out in a PHI 5000 VersaProbe II spectrometer with an Al Kα monochromatic X-ray beam. The X-ray source was operated at 25 W and 15 kV beam voltages. Dual-beam charge compensation with 7 eV Ar<sup>+</sup> ions and 1 eV electrons was used to maintain a constant sample surface potential regardless of the sample conductivity. The pass energy of the hemispherical analyzer for the iron (Fe 2p) spectra was fixed at 23.5 eV and for other elements at 46.95 eV. The spectra were charge corrected to the mainline of the carbonC1s spectrum set to 284.8 eV.
