Cavity ring-down absorption spectroscopy was used to measure k(HCO + O2) = (5.9 ± 0.5) × 10-12, k(HCO + NO) = (1.9 ± 0.2) × 10-11, and k(HCO + Cl2) = (7.6 ± 0.7) × 10-12 cm3 molecule-1 s-1 in 4-10 Torr of N2 diluent at 295 K. FTIR/smog-chamber techniques were used to measure the following rate constant ratios in 15-750 Torr of N2 diluent at 295K: k(HCO + O2)/k(HCO + Cl2) = 0.85 ± 0.02, k(HCO + NO)/k(HCO + Cl2) = 2.80 ± 0.10, and k(HCO + NO2)/k(HCO + Cl2) = 8.45 ± 0.38. Consistent results were obtained from the two different techniques. In 15-700 Torr of N2 diluent at 295 K the reaction of HCO with Cl2 proceeds via a single channel giving HC(O)Cl + Cl, reaction of HCO with NO gives CO in a yield indistinguishable from 100%, and reaction of HCO with NO2 gives a 70% yield of CO and a 30% yield of CO2. Ab initio calculations show that the reaction of HCO radicals with Cl2 proceeds via the formation of the HC(O)Cl2 complex, which decomposes, rapidly to HC(O)Cl and a Cl atom.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry