Calculations of total electron impact ionization cross sections for fluoroketone and fluoronitrile

Potential substitutes for SF₆ such as fluoroketone (C₆F₁₂O and C₅F₁₀O) and fluoronitrile (C₄F₇N and C₃F₅N) gases have been widely studied. The electron impact ionization cross section (Q_ion) is the key parameter in the simulation of gas discharges. Moreover, the Q_ion can be used in the preliminary screening of large scale alternatives of SF₆. In this paper, the Q_ion of C₆F₁₂O, C₅F₁₀O, C₄F₇N and C₃F₅N are calculated via the BEB method. The orbital parameters are obtained by Moller-Plesset perturbation function with second order approximation (MP2), which is validated by comparing the theoretical and experimental Q_ion for CH₃CN, CF₃CN, C₂H₄O, C₃H₆O and C₄H₈O. The linear relationship between the maximum Q_ion and polarisability supports the validity of the BEB method with MP2 function, which suggests that the results of the calculated maximum Q_ion for C₅F₁₀O and C₄F₇N are reasonable by BEB method. Lastly, the correlation between the maximum Q_ion and E_r is discussed. The analysis shows that there is a correlation between the maximum Q_ion and E_r, and the correlation coefficient reaches 0.598. It is thought that Q_ion can be as a new predictor to estimate the dielectric strengths for SF₆ replacements.