## 3 Results and Discussion
### Xps
#### 3.1.2 Plots of XPS Intensity of Core Spectra Against Scratching Environments
In a previous report [7], the percentages (%) for the two main oxygen components assigned to lattice O\({}^{2-}\) and lattice OH\({}^{-}\) were used, but in the present case, the XPS intensity obtained in the O 1s spectrum was distributed to the three components. In Table 3, the temperature dependence of the binding energies for the three components is summarized. The binding energies were almost independent of temperature and environments. The averages of the component binding energies for all environments were 530.7 eV (lattice O\({}^{2-}\)), 532.1 eV (lattice OH\({}^{-}\) and OH\({}^{\delta-}\)), and 533.5 eV (adsorbed H\({}_{2}\)O). The following results in Figure 5 are featured: (1) in the case of air, cyclohexane, water, ethanol, and acetone, i.e., except for benzene and methanol, the XPS intensity of the O\({}^{2-}\) component increased smoothly with increasing temperature. This suggests that the increase in XPS O\({}^{2-}\) intensity can be closely associated with the increase in the PE intensity with temperature during the Up1 scan (Figure 1 in Reference [6]); (2) interestingly, in the case of benzene and acetone, the temperature dependence of the XPS intensity of O\({}^{2-}\) closely resembled that of OH\({}^{-}\). This behavior may be associated with the fact that the glow curves of PE intensity during Up1 and Up2 temperature scans for both benzene and acetone took a considerably similar trend (Figure 1 in Reference [6]). Figure 6 shows the dependence of the XPS O\({}^{2-}\) intensity on the environments at the three temperatures. The value of intensity at 25 \({}^{\circ}\)C gradually increased as the environment shifted to the right, while that at 200 \({}^{\circ}\)C decreased for water, increased for methanol and ethanol, and then decreased for acetone. It is seen that the dependence of the XPS O\({}^{2-}\) intensity on the different environments is very similar--in particular, at 200 \({}^{\circ}\)C--to that of the XPS intensity of Fe 2\(p\), Fe 3\(p\), and O 1\(s\) demonstrated in Figure 4a-c, respectively, which exhibited a similar environment dependence. The XPS O\({}^{2-}\) intensity at 200 \({}^{\circ}\)C for the different environments increased in the following order: air (\(1.11\times 10^{4}\) counts) \(<\) water (\(1.50\times 10^{4}\)) \(<\) benzene (\(1.85\times 10^{4}\)) \(\approx\) cyclohexane (\(1.87\times 10^{4}\)) \(<\) acetone (\(1.92\times 10^{4}\)) \(<\) methanol (\(3.00\times 10^{4}\)) \(<\) ethanol (\(3.19\times 10^{4}\)). Interestingly, this order was nearly the same as that for the increase in magnitude of the swelling of the glow curve, called MSG, as shown in Figure 14 in Reference [5], which was air \(<\) water \(<\) benzene \(<\) cyclohexane \(<\) methanol \(<\) acetone \(<\) ethanol. The value of MSG was defined as the difference between the emission intensity at the selected seven temperatures in the observed glow curves and that on the straight line drawn between the intensities at 40 \({}^{\circ}\)C and 339 \({}^{\circ}\)C. The unit of MSG was represented by counts/s. The above findings strongly suggest that the formation of the peak appearing at around 200 \({}^{\circ}\)C in the PE glow curves can be associated with the growth of the component of O\({}^{2-}\), probably promoting the formation of iron oxide, including O\({}^{2-}\) ions in the overlayer. In Figure 6, it is seen that the value of XPS O\({}^{2-}\) intensity for air, cyclohexane, water, ethanol, and acetone increases with increasing temperature, while that for benzene and methanol remained at almost the same level at 200 and 339 \({}^{\circ}\)C.  
Figure 5: Temperature dependence of XPS intensity of three components of O\({}^{2-}\), OH\({}^{-}\), and H\({}_{2}\)O of the O 1\(s\) spectrum of scratched real iron surfaces on different environments: (1) air, (2) benzene, (3) cyclohexane, (4) water, (5) methanol, (6) ethanol, and (7) acetone. A typical example of the curve resolution of the O 1\(s\) spectrum for acetone is also shown.