Decomposition of $m$-xylene by $N_2 (A^3\Sigma _u^+ )$ and thin film deposition

The study has carried out on the determination of the collisional quenching rate coefficient of $N_2 (A^3\Sigma _u^+ )$ by $m$-xylene (C$_{8}$H$_{10})$, which has the weakest bonding strength among the three isomers of xylene. In our first attempt, the collisional quenching rate coefficients of $N_2 (A^3\Sigma _u^+ )$ by xylene ($o$-xylene, $m$-xylene, and $p$-xylene) have not yet been reported to the best of the authors' knowledge. The diffusion coefficient $D_{m1 }$of $N_2 (A^3\Sigma _u^+ )$ in N$_{2}$/(1ppm) $m$-C$_{8}$H$_{10}$ mixtures and the collisional quenching rate coefficient $k$' of $N_2 (A^3\Sigma _u^+ )$by $m$- xylene is determined as 151.5$\pm$0.7 cm$^{2}$/s and (4.4$\pm$0.6)$\times$10$^{-9}$ cm$^{3}$/s, respectively. Surprisingly, it is found that any by-product of xylene is deposited on the cathode, through repeated experiments, and then the current-voltage curves consistently shift to the higher-$E$/$p_{0}$ region. For the purpose of clarifying the reason behind this behavior, we have confirmed that these changes in the current-voltage curves are caused by the thin-film deposition of a by-product of decomposed xylene on the cathode surface by Auger electron spectroscopy.