Investigation of collision cross sections and mobilities for several clustered ions in O₂ at atmospheric pressure

A study of transport coefficients such as mobility and diffusion coefficient has been carried out in low pressure gases for collecting the fundamental data of discharge plasmas. Recently, the fundamental data are required for investigating atmospheric pressure plasmas. Therefore, we have investigated the clustered ion mobility and ion−molecule reactions in O₂ at high pressures including atmospheric pressure [1]. In this study, collision cross sections were investigated by calculations using mobilities for several clustered ions obtained by simulation results of ion drift using rate coefficients and ion mobility at atmospheric pressure in O₂ with a little amount of H₂O [2]. The collision cross sections for clustered ions as O₄⁻, O₂⁻·(H₂O), O₂⁻·(H₂O)₂ and O₂⁻·(H₂O)₃ were calculated by Mason−Schamp’s formula. As the results, mobility 2.31 cm²/V·s of O₂⁻‧(H₂O) is smaller than 2.40 cm²/V·s of O₄⁻, although the mass of O₂⁻‧(H₂O) is smaller than that of O₄⁻. The calculated results of the collision cross sections for O₄⁻ and O₂⁻·(H₂O) are 97.2 × 10⁻¹⁶ and 105 × 10⁻¹⁶ cm², respectively. The results suggest that the clustered ion mobilities depend on not mass but collision cross sections.