Time-resolved Fourier transform emission spectroscopy of CF3Br and CF3CFHCF3 in a pulsed electrical discharge

Abstract

The environmentally important decomposition of halogenated species CF3Br and CF3CHFCF3 in helium discharge plasma was investigated by time-resolved high-resolution Fourier transform infrared emission spectroscopy. Contrary to classical pyrolysis, a deeper fragmentation of precursors up to atoms and lower molecular species was observed. Excited molecular products CF, CF2 and CF4 achieved the maximal concentration in the afterglow. The high concentration of all these species is in agreement with a kinetic model based on radical chemistry. The non-detectable concentration of CF3 can be connected to its high reactivity and the formation of more stable products, CF4 and CF2, by addition or release of a fluorine atom, respectively. Other products included HF, HBr, CO and cyano compounds that were produced by secondary reactions with traces of water vapor, atmospheric oxygen and nitrogen present in original industrial samples as impurities.