Low temperatures and pressure dependence study of OH and CO reaction

OH radical and CO reaction is of crucial importance in the atmospheres of Mars and Earth. In this work, the reaction is studied under pseudo first-order conditions, monitoring the decay of OH by laser-induced fluorescence in the presence of a large excess of CO. We measured rate coeffs. for the reaction of OH with CO using laser photolysis/laser-induced fluorescence in 180K - 295K temp. under 100 to 200 torr. The pressure dependence study is ranging from 50 to 800 torr with Ar, He or N2 as bath gas. The biexponential decay of OH signal is obsd. and it is analyzed to derive information about the equil. const. for reaction: OH + CO ↔HOCO.