O(1D)和CD4反应的准经典轨线

在新的全域势能面上, 用准经典轨线方法细致地研究了O(¹D)+CD₄多通道化学反应的动力学．这个势能面是用交换不变多项式方法基于MRC+Q/aug-cc-pVTZ从头算点拟合得到的．通过计算得到了产物OD+CD₃、D+CD₂OD/CD₃O和D₂+DCOD/D₂CO的分支比、平动能分布以及角度分布,结果显示理论与实验吻合得较好, 从而说明了这个反应的同位素取代效应很小． 研究表明,O(¹D)+CD₄反应是经过陷入的抽取机理发生的： 最初主要通过D原子的抽取,并不是之前人们认为的直接C-D键的插入形成CD3OD中间物后再进而解离成各个产物通道．     

Photodissociation Dynamics of Methanol and Ethanol at 157 nm

利用氢原子里德堡时间飞行谱技术研究了超音速喷射分子束CH3OH和C2H5OH在157 nm的光解动力学,得到了氢原子产物的时间飞行谱．通过对谱图的拟合揭示出三个氢原子产物通道：OH上的氢原子脱落、CH3(C2H5)上的氢原子脱落和CH3O(C2H5O)的二次解离． 从得到的产物通道相对分支比可以知道CH3O的二次解离过程比C2H5O更明显．CH3OH解离的产物平均角分布各向异性参数β≈-0.3, 显示出跃迁偶极距接近垂直于C-O-H平面．C2H5OH解离的产物β≈-0.4,表明C2H5OH有更长的转动周期． 实验结果显示两个系统都经历了从3px到3s势能面的快速内转换, 然后在3s势能面上解离．CH3O+H产物平动能分布显示出CH3O的伞形振动激发或者CH3的摇摆振动激发,而C2H5O+H产物平动能分布没有振动态分辨．     

Br2+分子离子[1+1]双光子解离动力学

本文利用最近研制的低温离子阱-离子速度成像谱仪在冷离子束中研究了同位素质量分辨的⁷⁹Br₂⁺分子离子的[1+1]双光子激光解离动力学. 借助其1⁴Σ^-_u,3/2态为中间态使⁷⁹Br₂⁺共振吸收两个光子至4∽5 eV区域的高激发态并发生解离. 利用离子速度成像技术获得了光解产物⁷⁹Br⁺的二维速度分布和平动能释放谱. 通过平动能释放谱确定了不同解离能量处量子态分辨的解离产物通道分支比. 光碎片产物的角分布表明⁷⁹Br₂⁺分子离子的双光子解离是1⁴Σ^-_u,3/2态的ΔΩ=0平行跃迁至一个Ω=3/2高解离态发生的. 由于分子激发态中的强自旋-轨道耦合作用,高激发的四重态很可能参与到实验观测的光解过程.     

HOBr/DOBr态到态光解动力学的量子波包研究

本文基于高水平的多参考组态相互作用计算，报导了HOBr的最低三个单重态的三维势能面. 并且对该分子的光解离过程用实波包传播的方法进行了量子动力学研究，不仅计算结果得到了吸收光谱，而且还产生了光解产物的内态和角度分布. 结果与在紫外区域测得的HOBr的总吸收截面定量吻合，并很好的重现了实验上在266 nm处观察到的振动冷和转动热的光解OH/OD产物. 此外，预测了OH/OD的反冲各向异性参数接近平行跃迁的极限值，表明在266 nm处从基态(1¹A'')到2¹A''态的面内跃迁是一个快速的解离过程. 这与实验上从测量转动取向得出的结论一致. 然而，想要实现与实验上的定量一致，还需要考虑自旋和电子角动量的影响.     

CS2 分子 1 B2(1 Σ+u )态预解离动力学研究

研究了CS2 分子1B2 (1Σ+u )预离解态线形势垒下的g振动能级光解动力学,包括预解离寿命、产物振转布居、平动振动转动能量分配和解离通道分支比.在实验过程中,一束可调谐激光激发超声射流冷却的CS2 分子到1B2 (1Σ+u )电子态,光解产物CS用另一束可调谐激光通过激光诱导荧光(LIF)方法检测.通过拟合光解碎片激发谱的谱峰轮廓,获得了源于不同跃迁初始态的1B2 (1Σ+u )态g振动能级的预解离寿命.通过分析CS的LIF光谱,则获得了不同光解波长下CS碎片的v=0~8振动态布居、v=1、4 ~8振动态的转动布居、能量分配以及两个预解离通道CS(X1Σ+ ) +S(3PJ)和CS(X1Σ+ ) +S(1D2 )的分支比.实验还考察了初始态弯曲振动量子数v2″、振动角动量量子数l对解离动力学的影响.发现v2″的影响不大,而l的影响却是明显的.较大的l(=K)对应于较短的寿命和较小的通道分支比S(3PJ) /S(1D2 ),即大的l(=K)有利于预解离的发生,同时更有利于产生S(1D2 ).     

不同初始振动态下D2O在B带的态-态光解动力学

利用高精度的非绝热从头算势能面,采用量子实波包方法研究了D₂O在3个不同初始振动态(0,1,0)、(1,0,0)和(0,0,1)下光激发到~B态解离过程的态-态量子动力学．结果表明,由于初始振动波函数的形状不同,从不同振动态产生的吸收光谱、产物分布和产物分支比具有不同的动力学特性．弯曲振动态(010)的吸收谱呈现出两波瓣的形状且中间具有较浅的极小值,其基态产物OD( ~X)在高能量区域会出现轻微的振动态反转现象．所有初始振动态得到的激发态产物OD(_?)的振-转态分布都随能量的变化出现强烈的震荡,这是由于受到了激发态势能面上长寿命共振态的影响．反对称伸缩振动态(0,0,1)在高能量区域具有较大的产物分支比OD(_?)/OD( ~X),表明绝热通道在某些情形下是主要的解离通道．     

Theoretical Studies of O(1D)+HD (v=0, j=0, 1, 2, 3)→OD(H)+H(D) Reaction

利用准经典轨线计算方法在DK势能面上对O+HD进行了计算,获得了产物的反应截面和分支比OD/OH. 计算结果表明,当碰撞能由4.6 kJ/mol增加到46.0 kJ/mol时,产物的反应截面随着碰撞能的增加明显减小;产物的平均分支比随着转动量子数的增加逐渐减小.     

CS分子在207 nm的光解动力学研究：S(1D2)+CO(X1Σ+)产物通道

利用直流时间切片离子成像技术对OCS分子在紫外波段207 nm的光解产物S(¹D₂)进行了偏振实验研究. 通过在两种不同的共振增强多光子电离中间态，¹F₃和¹P₁, 以及四种不同的泵浦-探测激光偏振几何构型下探测了光碎片S(¹D₂)的角动量极化特性. 使用分子坐标系极化模型和实验室坐标系各向异性模型提取和分析出对应产物CO(X¹Σ⁺)的角分布.观测到的总平动能释放谱表明解离过程存在三种解离通道，分别对应于低、中、高平动能解离通道. 低、中平动能通道的来源与光解波长在较长波长下得到的双峰分布来源一致. 高平动能通道是一种新的解离通道，它来自于单重排斥态A(2¹A'')的直接解离.     

HNCO在201 nm的离子成像光解动力学:CO(X1Σ+)与NH(a1Δ)

本文通过时间切片离子速度成像技术在201 nm附近研究了HNCO分子在S₁电子激发态的光解动力学. CO产物通过共振增强多光子电离的方法进行了选态探测,获得了CO产物的振动基态和激发态切片影像. 从CO的影像得到了解离产物的能量分布和空间角分布,确定了NH(a¹Δ)产物的振转态分布信息. 研究发现¹NH的振动分支比(v=1/v=0)随CO(v=0)转动能的增大先增大后下降,展现了¹NH与CO之间特殊的态态相关性. 大约一半的可资用能分配给解离产物的平动自由度. 负的各向异性参数表明HNCO的光解是个快速的直接解离过程.     

CS2分子^1B2（^1∑u^＋）态预解离动力学研究

研究了CS2分子^1B2(^1∑u^+)预离解态线形势垒下的g振动能级光解动力学，包括预解离寿命、产物振转布居、平动-振动-转动能量分配和解离通道分支比．在实验过程中，一束可调谐激光激发超声射流冷却的CS2分子到^1B2(^1∑u^+)电子态，光解产物CS用另一束可调谐激光通过激光诱导荧光(LIF)方法检测．通过拟合光解碎片激发谱的谱峰轮廓，获得了源于不同跃迁初始态的^1B2(^1∑u^+)态g振动能级的预解离寿命．通过分析CS的LIF光谱，则获得了不同光解波长下CS碎片的v=0—8振动态布居、v=1、4—8振动态的转动布居、能量分配以及两个预解离通道CS(X^1∑^+)+S(^3PJ)和CS(X^1∑^+)+S(^1D2)的分支比．实验还考察了初始态弯曲振动量子数v2″、振动角动量量子数l对解离动力学的影响．发现v2″的影响不大，而l的影响却是明显的．较大的l(=K)对应于较短的寿命和较小的通道分支比S(^3PJ)／S(^1D2)，即大的l(=K)有利于预解离的发生，同时更有利于产生S(^1D2)．     

Relative transition probabilities in the A-X system of OD

As in a previous study on the OH molecule, branching ratios for emission from v′ = 0, 1 and 2 of the A²Σ⁺ state of OD have been measured using frequency-doubled, tunable dye laser excitation. The six independent ratios so obtained are used to assess calculations incorporating an electronic transition moment varying linearly with internuclear distance, a form judged superior from the OH work. Calculations of the rotational dependence of the transition probabilities in OD, and comments on some recent OH investigations are included.     

Dynamics of reaction of O with H2 and its isotopic variants in different rotational excited states

Scalar properties and vector correlations of the reactions O+H₂ →OH+H, O+HD→OH+D, O+DH→OD+H, and O+D₂ →OD+D at collision energies of 25 and 34.6 kcal/mole have been studied via quasi-classical-trajectory (QCT) method based on a BMS1 potential energy surface (PES). Generalized polarization-dependent differential cross section and the distributions of the dihedral angle at the collision energy of 34.6 kacl/mole are presented. The calculated results indicate that both reagent rotational angular momentum and the mass factor have a significant influence on the scalar properties and vector correlations of the title reactions.     

HXD中XH拉伸振动的振动跃迁偶极矩方向的理论研究

本文利用局域模研究了“重轻”体系简单分子XH伸缩振动的实验振动光谱. 键偶极方法进一步为实验光谱分析提供了帮助(假设XH伸缩振动的跃迁偶极矩沿着XH键方向排列). 通过局域模和多维简正模对HOD，HND^-，HCD，HSD，HPD^-和HSiD的XH伸缩振动的理论计算， XH伸缩振动的局部1D图片可以用于分析跃迁偶极矩倾斜角度. 在HOD分子中，OH伸缩振动的跃迁偶极矩远离OH键并且向远离OD键的方向倾斜；在HSD，HND^-，HPD^-，HCD和HSiD分子中的XH伸缩振动远离OH键，但朝向OD键，表明键偶极近似法不能很好地适用于“重轻体系”分子，重原子X可以影响跃迁偶极矩方向. 利用分子中原子理论分析了偶极矩的变化.     

T+OD体系的同位素交换反应动力学

基于DTO(Χ¹ A₁)分子的多体展式分析势能函数,用准经典的Monte Carlo轨迹法研究了T+OD(0,0)体系的分子反应动力学过程. 结果表明,在碰撞能较低(小于121.34 kJ ·mol^-1)时,可以生成长寿命DTO(Χ¹ A₁)络合物,并且该络合反应是有阈能反应,这与用多体项展式理论计算的DTO分子势能曲线结果一致. 随碰撞能增加,逐渐出现置换产物DT和OT,最终分子被完全碰散成D,T和O原子,而且反应T+OD(0,0)→OT+D,T+OD(0,0)→DT+O和T+OD(0,0)→D+T+O也是有阈能反应. 由于D和T原子的同位素效应,T+OD(0,0)与D+OT(0,0)体系的碰撞反应特征存在非一致性. 关键词： DTO 分子反应动力学 轨线 反应截面     

Accurate wavenumbers of the AΣ → XΠ (0, 0) and (1, 0) bands of OH and OD

The important A²Σ → X²Π (0, 0) absorption band of OH has been remeasured from spectra obtained by flash photolysis of H₂O₂ vapor. Accurate wavenumber measurements using thorium standards show that the previous rotational line measurements are about 0.1 cm^-1 too large. Measurements are also given for the (1, 0) band of OH and the (0, 0) and (1, 0) bands of OD.     

The characteristics of O＋HD （v = 0, j = 0） reaction dynamics

The analytical potential energy function of HDO is constructed at first using the many-body expansion method.The reaction dynamics of O+HD(v = 0,j = 0) in five product channels are all studied by quasi-classical trajectory(QCT) method.The results show that the long-lived complex compound HDO is the dominant product at low collision energy.With increasing collision energy,O+HD → OH+D and O+HD → OD+H exchange reactions will occur with remarkable characteristics,such as near threshold energies,different reaction probabilities,and different reaction cross sections,implying the isotopic effect between H and D.With further increasing collision energy(e.g.,up to 502.08 kJ/mol),O+HD → O+H+D will occur and induce the complete dissociation into single O,H,and D atoms.     

Theoretical study of stereodynamics for the reaction O(3P) +D2 (v=0, j=0) to OD+D and isotope effect

Quasi-classical trajectory (QCT) calculations have been performed to study the product polarization behaviours in the reaction O(³P) + D₂ (v= 0, j= 0)→OD + D. By running trajectories on the ³A′ and ³A″ potential energy surfaces (PESs), vector correlations such as the distributions of the polarization-dependent differential cross sections (PDDCSs), the angular distributions of P(θ_r) and P(ø_r) are presented. Isotope effect is discussed in this work by a comprehensive comparison with the reaction O(³P) + H₂ (v= 0, j= 0) → H + H. Common characteristics as well as differences are discussed in product alignment and orientation for the two reactions. The isotope mass effect differs on the two potential energy surfaces: the isotope mass effect has stronger influence on P(θ_r) and PDDCSs of the ³A′ PES while the opposite on P(ø_r) of the ³A″ potential energy surface.     

Difference frequency laser spectroscopy of OH and OD: Simultaneous fit of the infrared and microwave lines

The fundamental vibration rotation bands of OH and OD have been observed with an estimated accuracy of 0.001 cm^?1. Simultaneous fits of the infrared and microwave data are performed to improve the molecular constants in the v = 0 and v = 1 states. The correlated parameters γ_v and A_D are determined by combining the data for OH and OD. Some discussion is presented on the correlated molecular parameters.     

Dynamics of the reaction of O with H2 and its isotopic variants in different rotational excited states

Scalar properties and vector correlations of the reactions of O+H 2 →OH+H, O+HD→OH+D, O+DH→OD+H, and O+D 2 →OD+D at collision energies of 25 and 34.6 kcal/mole have been studied via the quasi-classical-trajectory (QCT) method based on a BMS1 potential energy surface (PES). The generalized polarization-dependent differential cross section and the distributions of the dihedral angle at the collision energy of 34.6 kacl/mole are presented. The calculated results indicate that both the reagent rotational angular momentum and the mass factor have a significant influence on the scalar properties and vector correlations of the title reactions.