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 fluorescence 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 processes of CF radicals in the gas phase. The lifetime of CF2 radicals was always longer than the geometrical diffusion time, and was almost linearly dependent on the gas pressure. The diffusion coefficient and the surface loss probability of CF2 were evaluated simultaneously from the pressure dependence of the decay time constant.