Simulation of dissociation of triplet states of organofluorine molecules in plasma.

Motivated by the search of new environmentally friendly organofluorine molecules for use in plasma technologies, we simulate dissociation of organofluorine molecules in low energy triplet states created by electron impact in plasma. We use the Ab Initio Multiple Cloning (AIMC) method [1], in which an ensemble of Ehrenfest trajectories describes the nuclear motion of the electronically excited molecule. Quantemol Electron Collisions (QEC) code [2], that interfaces with the UKRmol+ suite of molecular R-matrix codes [3] is used to determine the initial triplet states created by electron impact in plasma. Although AIMC has originally been developed for treating the dynamics of singlet states involved in photochemistry, it can still be used for the dynamics of low energy triplet states produced by electron impact. Our simulations yield branching ratios for various dissociation channels which produce neutral free radicals. The branching ratios are important for understanding chemical composition of plasma, but very difficult to measure experimentally. The calculations appear to yield very simple rules which can be used to predict dissociation channels even without calculations. It appears that the single bonds adjacent to double bonds in organofluorine molecules in low triplet state break more efficiently than other bonds.

[1] D. Makhov et al., Chem. Phys. 493 200 (2017).

[2] B. Cooper et al., Atoms 7 97 (2019).

[3] Z. Masin et al., Comput. Phys. Commun 249 107092 (2020).