The reaction of OH with C2H2 at atmospheric conditions investigated by cw-uv-laser-longpath-absorption of OH.

A sensitive CW-UV-laser absorption method at 308 nm has been used to investigate the pressure dependence of the kinetics of OH reactions with C2H2. OH radicals are generated by excimer laser photolysis of H2O at 193 nm or of H2O3 at 248 nm. Using an absorption light path of 151 m and accumulation 50 decay curves, OH concentrations in the range from 10 E10 down to 10 E7 cm E-3 can be detected in the presence of N2 at 10-1000 mbar. (ITA)