## 4 Results Characterization
### XPS Characterization  
To further study the changes in the elements (Cu 2p, F 1s, C 1s, O 1s, and N 1s) and materials on the surface of copper samples, an energy spectrum scanning test was performed with XPS. The best spatial resolution of XPS is better than 20 \(\upmu\)m, and the imaging spatial resolution is better than 3 \(\upmu\)m. The track of the element being tested was selected according to internationally accepted test rules. After using the XPS Peak software to perform a Shirley-type fitting deduction on the energy spectrum background [22], the Gaussian algorithm was used for peak fitting, and the chemical state of the element was determined by using the National Institute of Standards and Technology (NIST) XPS database and previous studies as references [23; 24; 25]. Figure 7a presents the photoelectron spectroscopy curve of the 2p orbital of Cu element on the surface of a copper sample. After the peak photo-matching of the secondary photoelectron emission peak of the copper element, the five peaks with electron binding energies of 932.7, 934.6, 944.8, 952.5, and 952.7 eV were Cu\({}_{2}\)O 2p\({}_{3/2}\), CuO 2p\({}_{3/2}\), CuO 2p\({}_{3/2}\), Cu\({}_{2}\)O 2p\({}_{1/2}\), and CuO 2p\({}_{1/2}\), respectively. The secondary photoelectron emission peak at 954.90 eV in Figure 7a exceeds the photoelectron binding energy generated by the transition of the Cu element level. Therefore, this peak should be the photoelectron emission peak of the other elements. The change in CuO and Cu\({}_{2}\)O content in Figure 7a corresponds to the change in the color of the copper surface. The copper energy spectrum scanning results indicate that the surface of the copper sample mainly contains CuO and Cu\({}_{2}\)O produced via oxidation of the copper surface. Copper and pure C\({}_{5}\)F\({}_{10}\)O and C\({}_{5}\)F\({}_{10}\)O/N\({}_{2}\) gas mixtures react at high temperatures to form CuF\({}_{2}\) (Figure 7b). Some Cu also reacts with the C\({}_{5}\)F\({}_{10}\)O/N\({}_{2}\) gas to form compounds that contain Cu, C, and N (Figure 7e). The surface copper detection results recorded at 120 \({}^{\circ}\)C are consistent with the control group, thereby indicating that copper shows good compatibility with the C\({}_{5}\)F\({}_{10}\)O/air gas mixture at 120 \({}^{\circ}\)C (the XPS test results are consistent with the FESEM results). Some Cu participates in the reaction as the experimental temperature increases. Figure 7: _Cont._  
Figure 7b presents the photoelectron spectroscopy of the 1s orbital of the F element on the surface of the copper sample. No F element was detected in the control group. In the pure C\({}_{5}\)F\({}_{10}\)O experimental group, some C\({}_{5}\)F\({}_{10}\)O was decomposed on the copper surface at a high temperature, and CuF\({}_{2}\) and C-F bonds were detected at binding energies of 684.7 eV and 688.8 eV. The detected CuF\({}_{2}\) is a product of the reaction of C\({}_{5}\)F\({}_{10}\)O molecules with CuO on the copper surface. CuF\({}_{2}\) and C-F bonds were detected in the C\({}_{5}\)F\({}_{10}\)O/N\({}_{2}\) experiment group, thereby suggesting that the C\({}_{5}\)F\({}_{10}\)O/N\({}_{2}\) gas mixture reacted with copper at an elevated temperature and that the relative content of CuF\({}_{2}\) and C-F bonds increased along with the experiment temperature. By contrast, the C\({}_{5}\)F\({}_{10}\)O/air gas mixture experiment group tended to decrease the relative content of CuF\({}_{2}\) and C-F bonds as the experiment temperature increased. CuF\({}_{2}\) was not detected at 220 \({}^{\circ}\)C, and the fluorine element on the copper surface was mainly present as a C-F bond. In the experiment group, the fluorine element mainly existed in the form of a C-F bond, a small amount of fluorine existed in the form of CuF\({}_{2}\), and the C-F bond did not show much difference across each experimental group.