O atom kinetics in RF CCP oxygen plasma at increased pressures*

In this study, the 81 MHz symmetric CCP discharge in quartz tube at increased pressures (10 to 100 Torr) was used to study O$_{2}$ dissociation mechanism. The use of both spatially resolved and time-resolved actinometry technique on Kr in the modulated rf discharge allowed measuring atom loss frequency $\nu$$_{loss}$$^{O}$ and dissociation degree and thereby determining dissociation rate constant k$_{diss}$$^{O2}$. The O atom loss is connected with surface recombination at lower pressure and volume reactions at the higher pressure. The variation of plasma parameters allowed studying the O$_{2}$ dissociation and O atom loss mechanisms in a wide range of gas temperature from $\sim$ 500 K up to 1800 K. The possible mechanism of increasing k$_{diss}$$^{O2}$ at low E/N as well as the role of ozone generation in $\nu$$_{loss}$$^{O}$ is discussed in detail.