Laboratory Studies of Some Thermal Reactions Involving NOy Species

An investigation of the mechanism of heterogeneous PAN decomposition was made. It was found that the reactions of the acetylperoxy radical were influenced slightly by the presence of surfaces. The temperature dependence of the sidechannel of the reaction between nitrate radicals and nitrogen dioxide, producing nitric oxide, nitrogen dioxide and molecular oxygen, was investigated. Monte Carlo simulation calculations of the photolysis of nitrogen dioxide were performed. Reaction products and in some cases also kinetic information were determined for several alkenes reacting with nitrate radicals. Structurally related, simple carbonyl compounds were among the more abundant products together with nitrooxy-substituted ketones and alcohols. A systematic investigation of reaction kinetics and product distributions from nitrate radical reaction with aliphatic esters, ethers and alcohols was made. The rate coefficients for ethers and alcohols were found to be substantially higher than expected from simple correlations, e.g. for alkanes. This is interpreted as an effect of the oxygen atom, weakening adjacent hydrogen-carbon bonds. The oxygen atom also has an additional influence, possibly via stabilisation of the transition complex. The nitrate radical is quite specific for abstraction of the weakest bonded hydrogen atom and reaction products can often be deduced from this information combined with common knowledge of atmospheric gas-phase reactions.