## 3 Results and Discussion  
### Xps  
#### 3.1.1 Dependence of XPS Spectra on Scratching Environments and Temperature  
Figure 1 shows the Fe 2\(p\) spectra at 25, 200, and 339 \({}^{\circ}\)C for real iron surfaces scratched in different environments. The XPS measurement was carried out after the PE measurement at 25, 200, and 339 \({}^{\circ}\)C for real iron surfaces scratched in the environments. Although we already reported the change of Fe 2\(p\) and Fe 3\(p\) spectra with the increasing temperature for the scratched samples [6], in the present study, according to References [15; 16; 17; 18; 19; 20], we reexamined in more detail the dependence of Fe 2\(p\) spectra on temperature and scratching environments. The intensities and binding energies of peaks--called Peaks I, II, and III--observed in the Fe 2\(p\) spectra are listed in Table 1. In Figure 1 and Table 1, it is seen that the Fe 2\(p\) spectrum at 25 \({}^{\circ}\)C for all environments had two small peaks (Peaks I and III) appearing at the binding energies of approximately 721 and 708 eV, respectively, and a main peak (Peak II) in theneighborhood of 712 eV. At 200 and 339 \({}^{\circ}\)C, while the small peaks almost disappeared, only the main peak with a similar shape, which increased in the intensity with temperature, was maintained at almost the same binding energy. We considered the assignment of these peaks. According to Reference [15], the binding energies of 706.75 eV (Fe 2\(p\)3/2) and 719.95 eV (Fe 2\(p\)1/2) are reported for the Fe metal, and those of 710.7 eV (Fe 2\(p\)3/2) and 724.3 eV (Fe 2\(p\)1/2) are reported for Fe\({}_{2}\)O\({}_{3}\). Additionally, [PERSON] and [PERSON] [16] reported both 706.8 eV and 719.8 eV for Fe\({}^{0}\), 709.8 eV, a satellite peak, and 722.8 eV for Fe\({}^{2+}\), and 711.2 eV, a satellite peak, and 724.3 eV for Fe\({}^{3+}\). According to [PERSON] and [PERSON] [17], the following binding energies (eV) were assigned for Fe 2\(p\)3/2 for iron metal and iron oxides: 706.9 (Fe metal), 709.5 (FeO), 708.3 (Fe\({}_{3}\)O\({}_{4}\)), 711.0 (\(\alpha\)-Fe\({}_{2}\)O\({}_{3}\) and \(\gamma\)-Fe\({}_{2}\)O\({}_{3}\)), and 711.9 (\(\alpha\)-FeCOOH). According to the above references, the two small peaks observed in the present Fe 2\(p\) spectra can be attributed to Fe 2\(p\)3/2 and Fe 2\(p\)1/2 for Fe metal, respectively, and the main peak at 712 eV seems to originate from mainly Fe 2\(p\)3/2 peak for FeOOH. Here, the fact that the small peaks for Fe metal appeared at the binding energies of approximately 1 eV higher than those reported in References [15; 16; 17] suggests that the chemical shift may be caused by the effect of scratching on the metal, while the observed binding energy of 712 eV was almost identical to the value for the Fe 2\(p\)3/2 of FeOOH [17], resulting in the assignment of FeOOH. The chemical shift seems to be small for FeOOH. In Figure 1, at 200 and 339 \({}^{\circ}\)C, satellite peaks assigned to Fe 2\(p\)3/2 of Fe\({}^{2+}\) and Fe\({}^{3+}\) [16] seem to be negligible. It was reported that satellite peaks for FeO and Fe\({}_{2}\)O\({}_{3}\) were absent for Fe\({}_{3}\)O\({}_{4}\)[18; 19]. [PERSON] et al. [20] reported Fe 2\(p\) spectra of Fe\(-\)O\(-\)N films formed by sputtering iron metal at different O\({}_{2}\) flow rates (\(f_{O2}\)) in an Ar\(-\)N\({}_{2}\)\(-\)O\({}_{2}\) gas mixture, and explained that the film structure with increasing O\({}_{2}\) flow rate changes from a mixed phase of metallic Fe and Fe\({}_{3}\)O\({}_{4}\) initially, to a mixed phase of FeO and \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\), and finally, to \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\). The shape of the Fe 2\(p\) spectrum at 25 \({}^{\circ}\)C obtained in our present experiment was very similar to that of the Fe 2\(p\) spectrum in the low-O\({}_{2}\) flow rate stage in the range of 705\(-\)725 eV as shown in Figure 3a in Reference [20], except for the shift in binding energy.