LOSS PROCESSES OF CF AND CF2 RADICALS IN THE AFTERGLOW OF HIGH-DENSITY CF4 PLASMAS

The decay time constants of CF and CF2 radical densities were measured in the afterglow of high-density CF4 plasmas by laser-induced fluores cence spectroscopy. As a result, it was found that the lifetime of CF radicals was shorter than the geometrical diffusion time determined by the chamber design. This indicates the presence of fast loss processe s of CF radicals in the gas phase. The lifetime of CF2 radicals was al ways longer than the geometrical diffusion time, and was almost linear ly dependent on the gas pressure. The diffusion coefficient and the su rface loss probability of CF2 were evaluated simultaneously from the p ressure dependence of the decay time constant.