Reaction of CF3radicals on fused silica between 320 and 530 K

摘要

The reaction between CF3radicals and silicon oxide (fused silica) surface was studied in a VLPFgr; flow reactor (sim;0.1ndash;3 mTorr) as functions of surface temperature (320ndash;530 K) and CF3concentration. The CF3radicals were generated from CF3I by CO2laser photolysis, and the subsequent gashyphen;phase reaction products were followed by mass spectroscopy. The surface reaction was found to yield CO, HF, CO2, COF2, and SiF4. It was found that H2O residing on the silicon oxide surface was largely responsible for the oxygenhyphen; and hydrogenhyphen;containing products, and that little etching of the SiO2itself occurred under these conditions. The rates for the irreversible surface loss of CF3, and for the formation of CO were both first order with respect to lsqb;CF3rsqb;. These were found to be temperature dependent withEabartil;4.7 and 7.5 kcal/mol, respectively. The CF3surface loss rate indicates that the sticking coefficient for this radical on quartz is between 0.0014ndash;0.017 for the temperature range of this study.