Rate coefficient of CO2 splitting in recombining H2 and He plasmas with ultralow electron temperatures

Abstract

We investigated CO2 splitting in recombining H2 and He plasmas with ultralow electron temperatures between 0.1 and 0.4 eV. The conversion from CO2 to CO and O2 was observed in the ultralow-temperature plasmas. Since the rate coefficients of dissociation of CO2 via electronic excited states are negligible at the ultralow electron temperature, the present experimental result gives us corroborative evidence of the CO2 splitting via vibrational excited states. The rate coefficient of the CO2 splitting, which was evaluated from the temporal variation of the CO2 density, decreased clearly with the electron temperature. In addition, the rate coefficient observed in the ionizing H2 plasma with an electron temperature of 4 eV was one order of magnitude smaller than that observed in the recombining plasmas. It has been shown that the CO2 splitting via vibrational excited states has a larger rate coefficient than that via electronic excited states.