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Register a new userElectron swarm parameters in C$_2$H$_2$, C$_2$H$_4$ and C$_2$H$_6$: measurements and kinetic calculations
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N R Pinh~ao
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This work presents swarm parameters of electrons (the bulk drift velocity, the bulk longitudinal component of the diffusion tensor, and the effective ionization frequency) in C$_2$H$_n$, with $n =$ 2, 4 and 6, measured in a scanning drift tube apparatus under time-of-flight conditions over a wide range of the reduced electric field, 1 Td $leq,E/N,leq$ 1790 Td (1 Td = $10^{-21}$ Vm$^2$). The effective steady-state Townsend ionization coefficient is also derived from the experimental data. A kinetic simulation of the experimental drift cell allows estimating the uncertainties introduced in the data acquisition procedure and provides a correction factor to each of the measured swarm parameters. These parameters are compared to results of previous experimental studies, as well as to results of various kinetic swarm calculations: solutions of the electron Boltzmann equation under different approximations (multiterm and density gradient expansions) and Monte Carlo simulations. The experimental data are consistent with most of the swarm parameters obtained in earlier studies. In the case of C$_2$H$_2$, the swarm calculations show that the thermally excited vibrational population should not be neglected, in particular, in the fitting of cross sections to swarm results.
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We calculated reaction rate constants including atom tunneling of the reaction of dihydrogen with the hydroxy radical down to a temperature of 50 K. Instanton theory and canonical variational theory with microcanonical optimized multidimensional tunneling (CVT/$mu$OMT) were applied using a fitted potential energy surface [J. Chem. Phys. 138, 154301 (2013)]. All possible protium/deuterium isotopologues were considered. Atom tunneling increases at about 250 K (200 K for deuterium transfer). Even at 50 K the rate constants of all isotopologues remain in the interval $ 4 cdot 10^{-20}$ to $4 cdot 10^{-17}$ cm$^3$ s$^{-1}$ , demonstrating that even deuterat
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