Kinetics of gas-phase tropospheric reactions of organic solvents and hydroxyl radical by laser photolysis laser-induced fluorescence

Abstract

Hydroxyl gas-phase reactions play a very important role in air pollution. For the majority of chemical compounds of the atmosphere, the reaction with OH radical s is an intermediate one, part of a long chain reaction. A laser photolysis-laser induced fluorescence technique has been sued to study OH reaction kinetics with dioxane. The apparatus consists of two synchronized pulsed laser systems, a six cross flow/steady gas reactor, a photomultiplier for LIF detection and control electronics. The first laser is used for the production of OH radicals by photolysis. The second laser provides a probe-beam which excites the OH radical electronically. Then, the relative population of OH radicals is monitored time-resolved by laser induced fluorescence. All experiments are performed under pseudo- first order kinetic conditions. The major advantages of this technique are: (1) Capability to measure OH reaction kinetics over an extended temperature range, with different reactants using the same apparatus. (2) Generation of a clean source of OH radicals. (3) Capability of atmospheric pressure measurements. (4) Micro-scale simulation of atmospheric reactions.