The reaction of OH with CO measured under atmospheric conditions

The reaction of OH with CO is the most important OH removal mechanism in the lower atmosphere. It has been studied extensively in N2 E1-5. Not many absolute determinations of the rate constant have been done under atmospheric conditions. A laser detection method for OH in the UV at 308 nm was used for the study of the kinetics of the reaction of OH with CO under environmental conditions (N2 and O2 at atmospheric pressure). The experimental setup consists of a long path absorption cell, a uv-cw laser as analytical light source for OH, a differential photodiode detection system and an excimer laser for pulsed production of OH radicals. A detection limit for OH of 10E7 cm-3 is obtained at 40 Mys rise time. Due to the experimental conditions interfering consecutive radical-radical reactions have definitely been excluded. (ITA)