化学反应散射共振态的实验检测与理论模拟

化学反应中的散射共振态（或称反应性共振）控制着化学反应的分支比、产物的态分布及空间分布等。反应性共振的实验检测分为间接法和直接法。从理论上,一是构造反应体系的势能面,从势能面过渡态的结构来研究散射共振态;二是计算态-态反应动力学,尤其是用寿命矩阵来研究散射共振态。本文介绍反应性散射共振态的实验检测及理论模拟方法,并对今后的发展动向作出展望。     

HO+CH4→H2O+CH3反应的偏分势能面与散射共振态理论研究

用ab initio方法构建了该体系的偏分势能面, 并用其研究了该体系中散射共振态的形成机理, 估算了第一共振态寿命.     

Na+I2→Na++I-2 反应中散射共振态的理论研究

化学反应中散射共振态是在特定的碰撞能下生成的中间态, 具有如定域性、光谱等束缚态的性质. 它与势能面强相互作用区的性质有密切关系, 但又与化学反应的过渡态不同. 由于散射共振态对化学反应的分支比、产物的能量分配和产物的角分布等有重要影响, 因此, 一直是理论和实验化学家的前沿研究课题[1]. 理论上, 对散射共振态生成机理的研究多集中在单势能面(电子基态)反应, 如H+H2, F+H2, I+HI(以及H的同位素D)等[2], 而对两态势能面反应散射共振态的研究则少见报道. Na+I2Na++I-2 离子对生成反应的微分截面已用激光-交叉分子束装置进行了实验研究[3]. 本文用量子反应散射和量子化学ab initio相结合的方法研究第一共振峰所对应的共振能、共振宽度、共振寿命、几何结构及电荷分布, 对共振类型作了指认, 分析了共振态的生成机理.     

Na+I_2——Na~++I_2~-反应中散射共振态的理论研究

化学反应中散射共振态是在特定的碰撞能下生成的中间态 ,具有如定域性、光谱等束缚态的性质 .它与势能面强相互作用区的性质有密切关系 ,但又与化学反应的过渡态不同 .由于散射共振态对化学反应的分支比、产物的能量分配和产物的角分布等有重要影响 ,因此 ,一直是理论和实验化学家的前沿研究课题 [1] .理论上 ,对散射共振态生成机理的研究多集中在单势能面 (电子基态 )反应 ,如H+ H2 ,F+ H2 ,I+ HI(以及 H的同位素 D)等 [2 ] ,而对两态势能面反应散射共振态的研究则少见报道 .Na+ I2 Na++ I- 2 离子对生成反应的微分截面已用激光 -交…     

I＋HI（y=0）→IH（y′=0）＋I体系散射共振态的理论研究

在QCISD(T)//MP2水平下，分别采用6-311 G基组和SDD基组对重-轻-重反应I HI(p=0)→IH(√=0) I中的H和I的偏分势能面进行了abinitio计算.指认出在0～0.58eV碰撞能范围内所产生的6个散射共振态为Feshbach共振，并与文献报道的量子散射理论计算与高分辨阈值光分离光谱实验结果进行了比较.     

I+HI(v=0)→IH(v′=0)+I体系散射共振态的理论研究

在 QCISD ( T) / / MP2水平下 ,分别采用 6-3 1 1 ++G* * 基组和 SDD基组对重 -轻 -重反应 I+HI(ν=0 )→ IH(ν′=0 ) +I中的 H和 I的偏分势能面进行了 ab initio计算 ,指认出在 0～ 0 .5 8e V碰撞能范围内所产生的 6个散射共振态为 Feshbach共振 ,并与文献报道的量子散射理论计算与高分辨阈值光分离光谱实验结果进行了比较 .     

CH4+O(3P)→CH3+OH反应的准经典轨线研究

用准经典轨线方法研究了O（3P）与CH4的反应，计算结果表明，CH4（υ＝0，j＝0）与O（3P）的反应在低及高的碰撞参数下都是直接反应，无短寿命的碰撞复合物生成，产物OH以向后散射为主，基本上处于振转基态.CH4（υ＝1，j＝1）与O（3P）的反应在低及高的碰撞参数下反应机理不一样。在低碰撞参数下是直接反应，无短寿命的碰撞复合物生成，产物OH以向后散射为主，主要处于振动基态，转动基本上是冷的，但比高碰撞参数下的热.在高的碰撞参数下则生成短寿命的碰撞复合物，产物OH以向前散射为主，表现出明显的周边动力学反应的特征，主要处于振动激发态（υ＝1），但转动仍然是较冷的。     

共线量子散射方法研究D+CID体系

用共线量子散射方法计算D+CID体系的反应几率和传能几率。发现存在很强的振荡现象。体系的碰撞中间态的寿命的计算结果为fs-ps数量级。当某一反应通道打开时,在能量阈值附近通常都伴随着一些长寿命的碰撞中间态。这一点该体系中表现很比较明显。     

超球坐标下共线三原子反应散射的一阶Magnus数值传播法计算

使用一阶Magnus数值传播积分法计算了超球坐标描述下的共线三原子反应散射问题。应用于共线H+H_2和F+H_2体系得到了较好的结果。     

化学反应中散射共振态的理论研究进展

简述了化学反应中散射共振态的发现及研究意义, 介绍了散射共振态的理论方法, 对散射共振态进行了分类并给出不同类型散射共振态的形成机理, 分析了研究现状并对发展趋势作了展望。     

An Ab initio Theoretical Study on the Nonadiabatic Coupling for Na＋I2 Collision System

The ionic and neutral state potential energy surfaces (PESs) of Na I2 collision system have been calculated on QCISD(T) level by using ab initio method.The location and depth of the potential well,the collision radius and their fine structures have been analyzed at the equilibrium geometry of I2 molecule.The electronic transfer probabilities are also calculated in terms of Landau-Zener model.The lifetime of scattering resonance state is evaluated by the uncertainty principle.All the results have been compared with those obtained according to the Aten-Lanting-Los PES and Feng‘s PES.     

Velocity map imaging of ion-molecule reactive scattering: the Ar(+)+ N(2) charge transfer reaction

We present a velocity map imaging spectrometer for the study of crossed-beam reactive collisions between ions and neutrals at (sub-)electronvolt collision energies. The charge transfer reaction of Ar(+) with N(2) is studied at 0.6, 0.8 and 2.5 eV relative collision energies. Energy and angular distributions are measured for the reaction product N. The differential cross section, as analyzed with a Monte Carlo reconstruction algorithm, shows significant large angle scattering for lower collision energies in qualitative agreement with previous experiments. Significant vibrational excitation of N(+)(2) is also observed. This theoretically still unexplained feature indicates the presence of a low energy scattering resonance.     

I+HI'(v)→IH(v')+I'反应几率振荡行为的量子散射理论研究

本文基于振动绝热性分析, 用量子散射理论研究I+HI'(v)→IH(v')+I'反应几率的振荡行为, 其中双原子间相互作用势的振动本征态是Morse振子的严格解。在计算反应几率时采用分布高斯基(Distributed Gaussian Basis Sets; DGBS)展于方法, 既保持了反应几率的解析表达式, 又有效地简化了计算。计算结果明显地揭示了反应几率在低碰能区域的振荡行为。对反应机理也作了探讨。     

Theoretical study on the partial potential energy surface and formation mechanism of the reactive resonance state of HO + CH4 → H2O + CH3 system

In the course of an extensive investigation aimed at understanding the detailed mechanism of a prototypical polyatomic reaction, several remarkable observations were uncovered. To interpret these findings, we surmise the existence of a reactive resonance in this polyatomic reaction. The concerned system is HO + CH₄ → H₂O + CH₃, of which the partial potential energy surface is constructed by the coupling between vibrational models and reactive coordinates. Then we explain the formation mechanism of the reactive resonance state by the partial potential energy surface. Finally, we estimated the lifetime of the resonance state, and it is about 45fs. The study of the reactive resonance in a polyatomic reaction is more than just an extension from a typical atom + diatom reaction. As shown here, it holds great promise to disentangle the elusive intramolecular vibrational dynamics of the transient collision complex in the critical transition‐state region. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

A time-dependent wave-packet quantum scattering study of the reaction H2+(v = 0-2,4,6;j = 1) + He--> HeH+ + H

The quantum scattering dynamics calculation was carried out for the titled reaction in the collision energy range of 0.0-2.4 eV with reactant H(2) (+) in the rotational state j = 1 and vibrational states v = 0-2, 4, and 6. The present time-dependent wave-packet calculation takes into account the Coriolis coupling (CC) and uses the accurate ab initio potential-energy surface of Palmieri et al. [Mol. Phys. 98, 1835 (2000)]. The importance of including the CC quantum scattering calculation has been revealed by the comparison between the CC calculation and the previous coupled state (CS) calculation. The CC total cross sections for the v = 2, 4, and 6 states show collision energy-dependent behaviors different from those based on the CS calculation. Furthermore, the collision energy dependence of the total cross sections obtained in the present CC calculation only exhibits minor oscillations, indicating that the chance is slim for reactive resonances in total cross sections to survive through the partial-wave averaging. The magnitude and profile of the CC total cross sections for v = 0-2 in the collision energy range of 0.0-2.5 eV are found to be consistent with experimental cross sections obtained recently by Tang et al. [J. Chem. Phys. 122, 164301 (2005)] after taking into account the experimental uncertainties.     

Nonadiabatic reactant-product decoupling calculation for the F(2P(1/2)) + H2 reaction

In this paper we present a theoretical study using time-dependent nonadiabatic reactant-product decoupling method for the state-to-state reactive scattering calculation of F((2)P(1/2))+H(2) (nu=j=0) reaction on the Alexander-Stark-Werner potential energy surface. In this nonadiabatic state-to-state calculation, the full wave function is partitioned into reactant component and a sum of all product components. The reactant and product components of the wave function are solved independently. For the excited state reaction, the state-to-state reaction probabilities for J=0.5 are calculated. Comparing the state-to-state reaction probabilities, it is found that the vibrational population of the HF product is dominated by vibrational levels nu=2 and 3. The rotation specific reaction probabilities of HF product in j=1 and 2 are larger than those in other rotational levels. As the rotation quantum number j increases, the positions of the peak in the rotational reaction probability of HF product in nu=3 shift to higher collision energy.