## 3 Results and Discussion
### The PE Characteristics during Temperature Scan Against Scratching Environments
In the case of H\({}_{2}\)O, the H atom of H\({}_{2}\)O is attracted to the unshared electron pair of the O atom of Fe-OH, producing an electric dipole with its negatively charged end oriented outward, represented by Fe-OH-H\({}^{8+}-\)OH\({}^{8-}\). In the case of (CH\({}_{3}\))\({}_{2}\)CO, the H atom of Fe-OH is attracted to the unshared electron pair of the O atom of (CH\({}_{3}\))\({}_{2}\)CO, producing an electric dipole with its positively charged end oriented toward the outside, represented by Fe-O\({}^{8-}-\)H\({}^{8+}-\)O=C(CH\({}_{3}\))\({}_{2}\). Here, the symbol (-\(\cdot\)) denotes the hydrogen bond. Thus, these orientations of the electric charges contribute to the increase or reduction in \(\Delta\)E\({}_{\text{aUp1}}\), resulting in a significant influence on the PE intensity. Moreover, the decrease in \(\Delta\)E\({}_{\text{aUp2}}\) with the environments may be associated with a weak acid-base interaction between the molecule of the environments and the Fe-OH remaining on the surface even after the Down1 temperature scan. Here, we summarize the effect of the surface oxygen on the PE during the temperature scan. The air environment has the highest  
Figure 8: Plots of the activation energies of the PE quantum yields during the Up1 and Up2 temperature scans, \(\Delta\)E\({}_{\text{aUp1}}\) (**a**) and \(\Delta\)E\({}_{\text{aUp2}}\) (**b**), against the scratching environments. values of \(\Delta E_{\text{O1s}}\) and \(\Delta E_{\text{O2}}\)\({}^{-}\) (Table 4). This finding suggests that, since the surface oxygen species in the case of air at 25 \({}^{\circ}\)C is considerably strongly bound to the surface, the ability of the oxygen species to move with temperature is suppressed. Therefore, it can be said that the air environment acts to reduce the PE, producing the highest value of \(\Delta E_{\text{aUp1}}\)[5]. On the other hand, from Figures 4c and 7, it can be stated that the surface oxygen species for all environments plays a significant role in the increase in PE intensity. Figure 9 shows the relationship between the electron emission intensity at 339 \({}^{\circ}\)C during the Up1 and Up2 scans and the XPS O 1s intensity at 339 \({}^{\circ}\)C for all environments (Figure 4c). Although the data are widely scattered, it is confirmed that the increase in the surface oxygen favors the enhancement of electron emission intensity in both scans. We consider that the increase in the electron emission intensity in Figure 9 can be attributed to a large contribution of the O2\({}^{-}\) component of the O 1s spectrum at this temperature and the acid-base interaction between the environment molecule and Fe--OH. Here, we emphasize, again, that there are two types of action of the surface oxygen species on the PE during the temperature scan: one has the ability to strongly reduce the PE, and the other one is able to promote the PE with the aid of the interaction with molecules of the scratching environments. It is of interest to describe here, again, the relationship between \(N_{\text{Up1}}\) and \(\Delta E_{\text{aUp1}}\) and between \(N_{\text{Up2}}\) and \(\Delta E_{\text{aUp2}}\), which was reported in Reference [5]. In Figure 10, the values of \(N_{\text{Up1}}\) and \(N_{\text{Up2}}\) decreased with increasing \(\Delta E_{\text{aUp1}}\) and \(\Delta E_{\text{aUp2}}\), respectively. Clearly, this indicates that the total counts of electrons emitted from a scratched sample in the Up1 and Up2 temperature scans are closely associated with the activation energies (\(\Delta E_{\text{aUp1}}\) and \(\Delta E_{\text{aUp2}}\), respectively). Figure 10: Plots of the total count of PE electrons emitted during the Up1 and Up2 temperature scans against the activation energy for both scans, (**a**) \(N_{\text{Up1}}\) vs. \(\Delta E_{\text{aUp1}}\) and (**b**) \(N_{\text{Up2}}\) vs. \(\Delta E_{\text{aUp2}}\) for all scratching environments.