Discussion on the dissociation of fast HD^＋2 ions traversing thin foils

the discussion is on the following experimental results:The energy distribution of the H^ and D^ fragments resulting from the dissociation of HD^ 2 molecular ions at energy 1.4977 MeV has been measured using the Coulomb explosion techoique,The spectra were used to determing the binding energy of HD^ 2 and its structure,There existed differenoes between the spectral structures for proton and for deuteron.     

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.     

Cl+HD反应产物的极化与态分布

利用准经典轨线理论 ,在BW 2和G3两个势能面上 ,研究了Cl +HD反应的动力学 .计算结果表明 ,产物的转动取向对势能面及反应体系的质量因子非常敏感 .在BW 2势能面上 ,计算的两个产物的转动取向强于在G3势能面上计算的结果 ,而无论是在BW 2势能面上还是在G3势能面上 ,DCl产物的取向都强于HCl产物的取向 .计算结果还表明 ,在不同的势能面上反应物的转动激发对反应的影响有着显著的不同 .在BW 2势能面上 ,反应物的初始转动激发有利于Cl+HD反应的进行 ;而在G3势能面上 ,反应物的初始转动激发消弱了反应的反应性     

Quantum stereodynamics study for the reaction F + HD

This paper studies the quantum stereodynamics of the F + HD(υ = 0, j = 0) → HD + F/HF + D reaction at the collision energies of 0.52 and 0.87~kcal/mol. The quantum scattering calculations, based on Stark-Werner potential energy surfaces, show that the differential cross sections for the HF(υ' = 2) + D and DF(υ' = 3) + H channels are consistent with the recent theoretical results. Furthermore, the product rotational angular momentum orientation and alignment have been determined for some selected rovibrational states of the HF + D and DF + H channels.     

Measurement of the resonant d(mu)t molecular formation rate in solid HD

Measurements of muon-catalyzed dt fusion ( d(mu)t-->4He + n + mu(-)) in solid HD have been performed. The theory describing the energy dependent resonant molecular formation rate for the reaction (mu)t + HD-->[(d(mu)t)pee](*) is compared to experimental results in a pure solid HD target. Constraints on the rates are inferred through the use of a Monte Carlo model developed specifically for the experiment. From the time-of-flight analysis of fusion events in 16 and 37 microg x cm(-2) targets, an average formation rate consistent with 0.897+/-(0.046)(stat)+/-(0.166)(syst) times the theoretical prediction was obtained.     

反应物的振动对碰撞反应(He, HD+)积分截面的影响

采用准经典轨线方法[1,2]计算了碰撞能范围为0.6～1.2电子伏时反应He+HD+ (v=1,j=0,1,2,3)→HeH++D和He+HD+ (v=1,j=0,1,2,3)→HeD++H的积分截面.通过跟有效的实验结果对比,发现计算结果略低于实验值,这可能是由于在计算中没有考虑量子效应而导致的.通过准经典轨线的计算结果与Tiwari等人的CS理论计算结果对比发现结果是基本相符合的,尤其是在几个碰撞能下几乎完全吻合.另外通过对比总结分析了V16以及V112势能面在不同的碰撞能以及不同的振转态下与CS理论计算的结果符合情况是的差异.同时重点分析了反应物的振转态对于反应的生成物以及积分截面的影响.     

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.     

采用量子波包方法和准经典轨线方法研究S(~3P)+HD反应

利用量子波包方法和准经典轨线方法在一个新的3A′′势能面上研究了S(3P)+HD→SD+H和SH+D反应的动力学性质.计算得到了两个反应通道在碰撞能为0.8—2.2 eV范围内的J=0反应几率、积分反应截面、内同位素因子和产物转动取向因子.这些结果揭示了S(3P)+HD反应非常明显的内同位素效应.通过对势能面和反应轨线的分析,我们发现了SD+H反应通道一个新的反应机制.S(3P)+HD反应的内同位素效应可以利用新发现的反应机制和反应的质量组合来进行解释.     

Observation of predicted resonance structure in the H+D2 --> HD(v(') = 0, j(') = 7) + D reaction at a collision energy of 0.94 eV

We present experimental verification of predicted resonance structure in the energy dependence of the H+D2 reaction. Specifically we predict and observe a broad resonance in the H+D2-->HD(v(') = 0,j(') = 7)+D reaction at a collision energy of 0. 94 eV. This resonance structure is roughly Gaussian with a full width at half maximum of 0.1 eV. These results represent the first experimentally observed resonance structure in the fundamental H+H2 reaction system.     

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.     

Hydrogen atoms in impurity-helium solids

Electron spin resonance (ESR) is employed to study atomic impurities (H and D) stabilized in impurity-helium (Im-He) solids at 1.35-1.5 K. The kinetics of the low temperature tunneling exchange reactions (D+H2-->H+HD, D+HD-->H+D2) are investigated in Im-He samples containing several different mixtures of hydrogen and deuterium impurities. The ESR line structures help determine the local environment of atoms trapped in Im-He solids. High concentrations of atomic hydrogen stored in Im-He solids may ultimately find applications in energy storage, matrix-isolation spectroscopy, and studies of different quantum statistical effects.     

HD^＋核间距及基态势能曲线的排列通道量子力学计算

依据排列通道量子力学（ＡＣＱＭ）的基本原理，对分子离子ＨＤ＾＋的核间距和基态势能曲线以及离解能Ｄｅ做了量论计算，得到了ＨＤ＾＋的核间距为２．０７２５ａｏ，并求得ＨＤ＾＋按两种方式离解时的势能曲线，认为多数ＨＤ＾＋应按Ｈ＾＋＋Ｄ的方式离解。通过比较计算，文章认为ＨＤ＾＋比Ｈ２＾＋更容易激发和离解，也更不稳定。同时文章对用ＡＣＱＭ解决非对称的同位素微团簇的一般方法做了简明阐述。     

分子高次谐波产生过程中同位素效应的理论研究

本文通过求解非玻恩-奥本海默近似条件下的一维含时薛定谔方程比较研究了H2+和HD+分子离子体系高次谐波谱的特征.数值计算结果表明,对于H2+体系干涉最小值对激光强度和分子初始振动态都很敏感,与此不同,HD+体系的干涉最小值的变化只依赖于初始振动态的选取.此外,借助于时频分布和电离几率,计算结果得到了合理的解释.     

分子高次谐波产生过程中同位素效应的理论研究简

本文通过求解非玻恩-奥本海默近似条件下的一维含时薛定谔方程比较研究了H+2和HD+分子离子体系高次谐波谱的特征.数值计算结果表明,对于H+2体系干涉最小值对激光强度和分子初始振动态都很敏感,与此不同,HD+分子离子体系的干涉最小值的变化只依赖于初始振动态的选取.此外,借助于时频分布和电离几率,计算结果得到了合理的解释.     

Molecular beam study of the apparent activation barrier associated with adsorption and desorption of hydrogen on copper

Molecular beam techniques are employed to study the adsorption and desorption of H₂ on the (100), (110), and stepped (310) crystal faces of copper. Each crystal is exposed simultaneously to a supersonic molecular beam of H₂ (energy variable from 1.6 to 10.7 kcal/mole) and a highly dissociated beam of deuterium. The majority of the H₂ molecules are scattered from the surface (i.e., are not adsorbed), while a portion of the remaining molecules adsorb dissociatively and react catalytically with adsorbed deuterium atoms to form HD molecules. These HD molecules desorb, and their angular distribution is measured by a rotatable mass spectrometer. For all three crystal faces, the distributions of desorbed HD deviate significantly from diffuse emission and are in excellent agreement with the results of our previous permeation study. From the dependence of the HD signal on the energy and incident angle of the H₂ beam, it appears that there are substantial energy barriers to adsorption, with these barriers depending on crystallographic orientation and acting essentially perpendicular to the surfaces. Both the energy dependence of the dissociative adsorption probability and the shapes of the HD angular distributions are nearly identical for the stepped (310) and (100) surfaces, thereby suggesting that ledge sites are not the principal regions responsible for adsorption of hydrogen on copper. The estimated adsorption probabilities versus energy are “S” shaped curves which appear to level off at values considerably less than unity. A comparison of our results with a very simple model with a single energy barrier to adsorption is qualitatively but not quantitatively satisfactory. An interpretation which includes a distribution of energy barriers is suggested.     

HD2+通过超薄碳膜的"尾流"效应

快分子离子穿过固体时会产生库仑爆炸(Coulomb Explosion),尾流效应是库仑爆炸中的一个显著特性.HD2 的爆炸能谱在实测中发现了一些引人注目的特性:1)H 的尾流效应特别显著;2)H 的能谱结构非常类似HeH 中H 的能谱;3)尾流效应在D 的能谱中体现得很弱.这些特性对分析了解HD2 的结构和物理化学性质有很大的帮助.本文依照“尾流”效应(Wake Effect)的等离子体模型,将爆炸中两个D 产物的尾流场近似认为一个He 的尾流场,模拟计算了1.4977 MeV HD2在100 nm碳膜中分解后0°方向的能谱形式.给出了相同条件下的实验结果,得到了非常接近的结果,并将两者作了比较和分析.文中同时给出了D 的实验能谱,对D 的尾流效应相对较弱作了分析,指出对不同产物分辨的差异、产物的非直线运动等是造成D 尾流效应弱的原因.     

Time-dependent quantum dynamics study for reaction of D+CH4→CH3+HD

The semirigid vibrating rotor target (SVRT) model has been applied to the study of the reaction of D+CH_4→CH_3+HD using a time-dependent wave packet method. The energy dependence of the calculated reaction probability shows oscillatory structures similar to those observed in the abstraction reaction of H+H_2, H+CH_4 etc. We have also studied the influence of rotational and vibrational excitation of the reacting molecule (CH_4) on reaction probability. The excitation of the H－CH_3 stretching vibration gives significant enhancement of reaction probability, which rises significantly with the enhancement of rotational quantum number j. Finally, we have compared the cross section and the rate constant of the D+CH_4 system with that of the H+CH_4 system.     

基于紫外激光光解离的慢速、干净的氟原子束源

在开展氟原子为反应物的低碰撞能散射实验时,慢速且干净的氟原子束非常关键. 本文介绍了一种简单但十分有效的基于紫外激光光解离的氟原子束源,该原子束的特性在F+HD反应散射实验的高分辨飞行时间谱中得到检验. 该束源为氟原子参与的低碰撞能研究奠定了重要基础.     

Charge transfer and elastic scattering in very slow H(+)+D(1s) half collisions

Charge transfer and elastic scattering probabilities were measured for half collisions between very slow protons and atomic deuterium. Collision energies down to a few meV, lower by more than an order of magnitude and with better energy resolution than previous measurements, were studied using the dissociation of the HD+ electronic ground state. The collision energy is determined a posteriori from the measured momentum vector of the dissociating charged fragments. The experimental results are in good agreement with our coupled channel calculations.