漫遊式過渡態對燃燒、化學推進及大氣化學反應之影響( I )

Abstract

近年來，漫遊式過渡態(roaming type transition states)被發現具有高度影響化學反應機 制及反應速度，本計劃將利用高階層量子化學計算詳細尋找此類过渡態對燃燒、火箭推進 及大氣化學反應之影響，諸如CH3OH, C2H5OH, C6H6 及C6H5CH3 之熱分解、CH3ONO2 及 (CH3)2NNO2 連鎖反應之起始機制、N2O4 之水分解、ClCl(O)O 在同溫層之生成和CH2OO 及CH3CHOO 直接轉換成HCOOH 及CH3COOH 之新機制等，在a-Si:H 薄膜生成機制之化 學反應機制方面，將繼續與布力汗博士合作研究。

Since the discovery of a roaming type transition state (RTS) in the photodissociation of CH2O, RTS’s have been found to exist in many decomposition reactions. Their existence allows us to account for formation of products which were believed to be kinetically inaccessible. For example, in the conventional potential energy surface of CH3NO2, the production of CH3O + NO could not be accounted for by its much higher transition state for CH3NO2 → CH3ONO → CH3O + NO than the production of CH3 + NO2. However, the discovery of a low-lying RTS CH3…NO2 → CH3O + NO allows us to explain the infrared multiphoton dissociation result of Y. T. Lee reported almost a quarter century ago. In this new funding period, various fundamentally important processes related to combustion, chemical propulsion and atmosphere chemistry will be investigated with a focus on the effects of roaming transition states on their kinetics and mechanisms of reactions. For example, the unimolecular decomposition reactions of CH3OH, C2H5OH, C6H6 and C6H5CH3, hydrolysis of N2O4, ClCl(O)O formation in the stratosphere, CH2OO and CH3CHOO isomerization to HCOOH and CH3COOH, and the chain-initiation mechanisms of CH3ONO2 and (CH3)2NNO2, among others.