Reaction of Hydroxyl Radicals with Two-and Three-Ring Polycyclic Aromatic Hydrocarbons: Determination of Hydrogen Abstraction and Hydrozyl Addition Rates under Combustion and Post-

University Of Dayton, Dayton OH

Investigators

Abstract

This is a study of the kinetics and mechanism of the gas-phase reaction of hydroxyl (OH) radicals with two-and three-ring polycyclic automatic aromatic hydrocarons (PAHs); this matter is of fundamental concern in both combustion and atmospheric chemistry. Experimental data are collected over extended temperature (300-1200oK) and pressure (50-750 torr) ranges. A pulsed laser photolysis/laser-induced fluorescence (PLP/LIF) technique refined for the study of semivolatile compounds is used for the kinetic and mechanistic measurements. Experiments include measurements of the effects of pressure on observed reaction rates and kinetic isotope effects. Experiments are complemented with a theoretical study of addition and obstruction reactions using ab initio quantum chemical methods. Transition-state theory (TST) is used to obtain rate constraints and branching rations, and Rice-Ramperger-Kassel-Marcus (RRKM) theory to estimate lifetimes of intermediates.