Theoretical Study On The Reaction Of Halogenated Alkoxy With Xo(X=N, O)

It is estimated that the free radical involving Chlorine and bromine species will not only damage the ozone layer in the atmosphere but also trigger the greenhouse effect. Because of the atmosphere chlorine and bromine halogenated alkane and free radicals will occur photodissociation chlorine and bromine reaction to release the radicals. As to its ultra-short life and the high activity, it is very hard to confirm the mechanism, microstructure and the evolution of it only through the experimental results. So the research of the small molecule free radical gas phase reaction mechanism using the method of theoretical calculation is very important for the protection of the atmosphere.In this thesis, the mechanism of the reactions of XO(X=N, O) in atmosphere has been studied with the MP2/6-31+G(d, p) level by using software of GAUSSIAN03 and POLYRATE9.7. At first, it optimized and analysised geometries of reactants, products, complexes and its stable point. With the same level, transition states have been set as the starting point and calculated the minimum energy path through the intrinsic reaction coordinate(IRC). Further confir- mation of the single-point energies are completed under the MC-QCISD high-level. Sure of the reaction main channel , and completed TST, CVT and CVT/SCT rate constant calculation work of the main channel.Through the optimized geometric structure, stable things simple harmonic oscillator frequency and theexperiment value the matching, inosculation is very good, proved model establishment and the rationality of selecting the basis set .Reaction barrier and the reaction enthalpy of equilibrium geometries have been obtained though calculation, based on the reaction of all feasible channel ande base data analysis ,it is sure that the hydrogen abstraction reaction channel silicon-based reaction channel, and the rest as minor reaction channel. In the 200-1500K temperature interval, the two system extract hydrogen reaction channels TST, CVT and CVT / SCT rate constants are obtained, the theoretical calculation result and the experimental value ratio is 1.01 , which verifies the reliability of the theoretical calculation, and gives the rate constant and the change of the temperature relations, for experimental are not the rate constant temperature range of provides theoretical predictions . In addition, when NO and O₂ attack discussed halogenated silane oxygen free radicals, NO reacts more easily than react O₂.