Abstract
The rate constant for the reaction (1), Cl + HO2 → HCl + O2, was measured using molecular modulation spectrometry to investigate HO2 radical kinetics in the modulated photolysis of Cl2;H2O2 mixtures at 760 torr pressure. HO2 was monitored directly in absorption at 220 nm, and k1 was determined from computer simulations of the observed kinetic behavior of HO2, using a simple chemical model. The results gave where k4 is the rate constant for the reaction of Cl with H2. A consensus value of k4 gave k1 = 6.9 × 10−11 cm3/molecule sec, independent of temperature in the range of 274–338 K with an overall uncertainty of ±50%. The relative importance of reaction (1) for the conversion of Cl to HCl in the stratosphere is discussed briefly.