全维高精度势能面上F+CH_(3)OH反应的产物振动态分布

Product Vibrational State Distributions of F+CH_(3)OH Reaction on Full-Dimensional Accurate Potential Energy Surface

甲醇与氟原子之间的抽氢反应可以生成HF和CH_(3)O、CH_(2)OH自由基等产物.该反应在环境化学、燃烧化学、辐射化学和星际化学中都非常重要.基于之前构建的全维高精度势能面,本文采用准经典轨线方法研究了该典型反应的动力学.特别是使用正则模式分析方法确定了多原子产物CH_(3)O和CH_(2)OH的振动态分布.研究发现,当反应物处于振转基态时,CH_(3)O和CH_(2)OH主要分布在基态.当反应物CH_(3)OH的OH伸缩模式激发为第一激发态时,产物CH_(2)OH的OH伸缩模式、扭转模式、H_(2)CO面外弯曲模式及其组合会被有效激发.在两条通道中,可用能量大部分都流入HF的振动能和产物的平动能,而自山基产物CH_(3)O或CH_(2)OH只得到非常少的能量,与实验结果一致,这也表明了自山基的旁观者性质.

The hydrogen abstraction reaction of methanol with fluorine atoms can produce HF and CH_(3)O or CH_(2)OH radicals,which are important in the environment,combustion,radiation,and interstellar chemistry.In this work,the dynamics of this typical reaction is investigated by the quasi-classical trajectory method based on a recently developed globally accurate full-dimensional potential energy surface.Particularly,the vibrational state distributions of the polyatomic products CH_(3)O and CH_(2)OH are determined by using the normal mode analysis method.It is found that CH_(3)O and CH_(2)OH are dominantly populated in the ground state when the reactants are at the ground ro-vibrational state.The OH stretching mode,torsional mode,H_(2)CO out-of-plane bending mode and their combination bands in the CH_(2)OH product can be effectively excited once the OH stretching mode of the reactant CH_(3)OH is excited to the first vibrationally excited state.Most of the available energy flows into the HF vibrational energy and the translational energy in both channels,while the radical products,CH_(3)O or CH_(2)OH,receive a small amount of energy,consistent with experiment,which is an indication of its spectator nature.