Mass-spectrometric study of ionic species present during the oxidation of CO and the decomposition of CO2 in a rf discharge

A mass spectrometric investigation has been performed of the ionic species present during the oxidation of CO and the decomposition of CO2 in a rf discharge. The relative ion current for each species is found to depend upon the discharge power and the gas pressure. A feature of particular interest is the observation that C+ is one of the dominant ions present. An analysis of the mechanisms for the formation of this species suggests that it is formed by the reaction CO+ + CO → C+ + CO2 which occurs in the sheath separating the plasma and the sampling orifice.