## 3 Results and Discussion
### Xps
#### 3.1.1 Dependence of XPS Spectra on Scratching Environments and Temperature
In Reference [20], at higher O\({}_{2}\) flow rates, a mixed phase of FeO and \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\) with a satellite peak at 718.9 eV, and \(\alpha\)-Fe\({}_{2}\)O\({}_{3}\) with a satellite peak at 719.2 eV were observed, respectively. Therefore, this suggests that the structure of the scratched surface at 25 \({}^{\circ}\)C may be composed predominantly of a mixed phase of metallic Fe and Fe\({}_{3}\)O\({}_{4}\). Furthermore, [PERSON] et al. [21] demonstrated a graphic representation of the oxides growth on iron surfaces as a function of oxygen exposures in Figure 5 in Reference [21], and they showed that the oxide films formed at low O\({}_{2}\) exposure consist of predominantly FeO\({}_{\rm x}\) and a thin film of FeOOH due to ambient background contamination on the top, while, at higher exposure, a trilayer oxide of FeO, Fe\({}_{3}\)O\({}_{4}\), and FeOOH is formed. In our present experiment, from the increase in intensity of the O 1s peak appearing at approximately 530.8 eV in the O 1s spectrum with an increase in temperature, which is shown in Figure 3, as well as the increase in the XPS O 1s intensity, which represents the total number of electrons counted in the O 1s spectrum, with temperature, which is shown in Figure 4c, it is clear that the surface oxygen content increased with the increasing temperatures. Upon making the increase in O\({}_{2}\) exposures in Reference [21] correspond to the increase of the surface oxygen amount with temperature in the present experiment, it is reasonable that the Fe 2\(p\) spectra at 200 and 339 \({}^{\circ}\)C shown in Figure 1 can be attributed to a mixed trilayer of FeO, Fe\({}_{3}\)O\({}_{4}\), and FeOOH. We show later that XPS intensities of not only Fe 2\(p\) and Fe 3\(p\), but also that of O 1s, increase with increasing temperature. We think that this occurred as a result of desorption of adsorbed water, the transport of oxygen species embedded in the inside to the surface, and the growth of the iron oxide species. Furthermore, we describe the contribution of the growth of non-stoichiometric oxide species, Fe\({}_{\rm x}\)O, to the TAPE. Here, it is interesting to note that Fe\({}_{3}\)O\({}_{4}\) (magnetic) contains both Fe\({}^{3+}\) and Fe\({}^{2+}\) at octahedral sites, and conduction can occur via the transfer of electrons from Fe\({}^{2+}\) to Fe\({}^{3+}\)[22]. It is thought that the transfer of electrons in Fe\({}_{3}\)O\({}_{4}\) may be associated with the transport of electrons across the overlayer in the PE. Figure 2 shows Fe 3\(p\) spectra at 25, 200, and 339 \({}^{\circ}\)C for real iron surfaces scratched in environments. In the Fe 3\(p\) spectrum at 25 \({}^{\circ}\)C, the shoulder peak assigned to Fe metal appeared at around 52.5 eV and was more evident than that in the Fe 2\(p\) spectra. This peak was gradually attenuated with temperature  
and disappeared at 339 \({}^{\circ}\)C. It is interesting that the Fe 3\(p\) spectra can be more strongly affected by the environment than the deeper core Fe 2\(p\) spectra shown in Figure 1.  
Figure 1: Temperature dependence of Fe 2\(p\) spectra of real iron surfaces scratched in different environments: (1) air, (2) benzene, (3) cyclohexane, (4) water, (5) methanol, (6) ethanol, and (7) acetone.