Optical emission actinometry and spectral lineshapes in RF glow discharges.

We describe the use of emission lineshapes for determining the mechanisms of excited state formation and assessing the validity of an actinometer. In CF(4)/O(2)/Ar plasmas, both Ar and F are created with cold (360 plus or minus 70K) translational distributions over a range of [F] from 0.4 to 4.0 x 10(14) atoms cm(-3). This implies that both species are created by electron-impact excitation and that Ar emission lineshapes in the sheath show substantial broadening during the cathodic part of the RF cycle, which implies that other excitation mechanism such as dissociation, attachment, ion impact, and charge exchange are important and that actinometry is not valid under these conditions. But, time-averaged Cl and Ar emissions in the discharge center have identical linewidths, so that actinometry can be used to determine Cl atom concentrations.