Production of CF2 radicals in a gas-discharge plasma through the electron-impact dissociation of CF4 molecules

The kinetics of the production and loss of CF2 radicals in a tetrafluorinem ethane plasma in a de discharge is studied. The absolute CF2 concentration is measured by a differential-absorption technique in the UV band of CF2 on the (1)A(1)(000) --> B-1(1)(060) and (1)A(1)(000) --> B-1(1)(030) transiti ons, and the electric field on the axis of the positive column of the disch arge is measured by a two-probe technique. All measurements are carried out in the pressure range from 0.2 to 1 torr at discharge currents from 5 to 4 0 mA. Based on the experimental data, the rate constant of electron-impact dissociation of CF4 molecules leading to the formation of CF2 radicals is d etermined as a function of the reduced electric field. The cross section fo r the process in question is inferred from a comparison of the published da ta on the dissociation cross sections for CF4 molecules with the results ob tained in this study.