AIMD calculation on electron ionization induced fragmentations of C5F10O and its discharge decomposition products

Recently, perfluoroketone C₅F₁₀O has been regarded as a promising alternative gas for SF₆, of which the global warming potential (GWP) is extremely high. C₅F₁₀O has a good insulation property and the GWP value is only 1, thus can be used as insulation medium in gas-insulated switchgears. In this study, the decomposition products of C₅F₁₀O under partial discharges are detected and qualitatively analysed by gas chromatography-mass spectrometry (GC-MS). The stable products like C₂F₆, C₃F₆, C₃F₈, C₄F₁₀ and CF₂O are formed. Meanwhile, to theoretically obtain the gas phase fragmentation pathways of C₅F₁₀O and its decomposition products upon 70eV electron ionization, a method of combined stochastic and ab initio molecular dynamics simulations are carried out. The calculation could be performed without preconceived fragmentation channels, which simulate standard electron ionization mass spectrometry (EI-MS) conditions. The significant peaks in the experimental mass spectrum of the molecules could be reproduced well, indicating that the simulation accurately predicts the decomposition channel after electron-impact ionization. Moreover, the fragmentation channels for C₅F₁₀O by 20 eV electron ionization, which is not standard in EI-MS but near the ionization threshold, are also calculated. We suggest that the quantum chemistry calculation method could provide an insight into fragmentation processes for different gases during discharges, which is still quite unclear for the novel SF6-alternative gases.