Time-dependent excitation in high and low frequency chlorine plasmas.

Time-resolved voltage, current, and optical emission from C1, C1+, C1(2)+ and small amounts of added Ar were studied in 0. 3 Torr chlorine discharges at 13.2MHz and 220kHz, above and below the ion transit frequency (ITF). Emissions, measured as a function of position, were deconvoluted to correct for the finite fluorescence lifetimes and extract the electron impact excitation rates. At 220kHz, emission falls to zero at the voltage zero point crossings due to electron energy relaxation and attachment. Emission and excitation in a sheath peak sharply about 70ns before electrode voltage reaches its positive maximum, and are stimulated by electron current. Emission then falls to zero and reaches a second maximum ~ 300ns after the electrode voltage reaches its negative peak.