MASS-SPECTROMETRIC STUDIES OF THE NEUTRAL AND IONIC PRODUCTS IN A CH4/O2 MICROWAVE-DISCHARGE PLASMA

An apparatus has been modified to sample the ionic and neutral species that emerge from microwave (MW) discharge in order to study the main products of CH4/O2 plasmas as a function of the partial oxygen pressure in a MW flow tube with 2.45 GHz, 10 W, and 2.2 Torr of total pressure. Mass spectrometry was used for the identification of the products. Studies have clearly shown the presence of various O-containing ionic species. They are classified as CnH2n+2OH+ (n = 1-9), CnH2n+2O2H+ (n = 1-6), CnH2nOH+ (n = 1-9), CnH2n10+ (n = 1-6), and so on, where n is the carbon number. The relative peak intensity profiles of these ionic products have been determined as a function Of 02 composition in the feed gas. It is apparent, from a comparison with the neutral species in this plasma, that the proton-transfer reaction plays a significant role in the ion chemistry of the CH4/02 plasma.