势垒高度对Cl+H2(D2)反应的影响

使用三维含时波包方法在两个势能面上研究了Cl+H2(D2)反应．所使用的两个势能面都是从CW(Capecchi和Wener)势能面得到的，第一个是CW势能面的基态面加自旋轨道耦合修正，第二个是CW势能面的基态面没有自旋轨道耦合修正．在这两个势能面上得到了碰撞能从0.1到1.4 eV的积分截面以及反应几率．对于Cl与D2反应，考虑自旋轨道耦合后由于势垒高度的增加反应截面向高能处有一个平移，但Cl与H2反应在低能处的反应活性反而增大了，原因是虽然自旋轨道耦合效应增加了势垒高度，同时减小了势垒宽度，隧道效应更加明显，而隧道效应在低能处起着比较重要的作用，所以反应活性比较大．当碰撞能大于0.7 eV时，没有考虑自旋轨道耦合时势垒高度较低，因而反应活性较大．     

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.     

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.     

State-to-state quantum dynamics of N(~2D)+HD(v=0,j=0) reaction

The N(~2D) + HD(v = 0, j = 0) reaction has been studied by a quantum time-dependent wave packet approach with a second-order split operator on the potential energy surface of Li et al.(Li Y, Yuan J, Chen M, Ma F and Sun M J. Comput.Chem. 34 1686). The rovibrationally resolved reaction probability, vibrationally integral cross section, and differential cross section of the NH + D and ND + H channel are investigated at the state-to-state level of theory. The experimental data of the thermal rate constant of two output channels is very scare, but the sum of the two output channels is in excellent agreement with the experimental data which was reported by Umemoto et al. It may imply that the thermal rate constants of the two output channels are accurate and reliable.     

氮分子{a'^1}\Sigma _g^ (v' = 0)和{a'^1}\Sigma _g^ + (v' = 1) + {b^1}\Pi _u(v' = 0) 广义振子强度的高能电子散射研究

利用快电子能量损失谱仪结合相对流量技术,在入射电子能量1500 eV和能量分辨70 meV的条件下,测量了氮分子{a''^1}\Sigma _g^ (v'' = 0)和{a''^1}\Sigma _g^ + (v'' = 1) + {b^1}\Pi _u(v'' = 0)激发态的广义振子强度。通过与已有的电子散射结果以及X射线散射结果对比发现,对于{a''^1}\Sigma _g^ (v'' = 0)和{a''^1}\Sigma _g^ + (v'' = 1) + {b^1}\Pi _u(v'' = 0),我们的结果与X射线散射结果在大动量转移出现差异,这表明对{a''^1}\Sigma _g^ (v'' = 0)和{a''^1}\Sigma _g^ (v'' = 1),即使入射电子能量1500 eV也没有达到一阶玻恩近似条件。在动量转移平方小于2 a.u.时, {a''^1}\Sigma _g^ + (v'' = 1) + {b^1}\Pi _u(v'' = 0)与X射线散射结果的符合表明,对{b^1}\Pi _u(v'' = 0),1500 eV入射电子能量已经达到一阶玻恩近似条件。     

D+CD4→CD3+D2反应的四维量子散射计算

运用约化维数量子动力学理论，利用含时波包法，对反应D+CD₄→CD_{3+D2进行了四维量子散射计算.将反应多原子CD4看作双原子D—CD 3，反应D+CD4→CD3+D2看作单原子-双原 子反应，把体系的反应简化为四维散射问题. 波函数的传播采用分裂算符法，为避免格点边界处含时波函数的边界反射，采用了光学吸收 势法，在格点边界处引入光学势，消除边界反射.根据CD4分子的C3v对称性， 选取了Jordan和Gilbert提出的半经验势能面.计算结果表明，反应概率随平动能的变化图像 ，呈现出显著的量子共振特性，这是很多提取反应的共同特征.而不同振动态下的反应概率 随平动能的变化表明，随振动量子数的增大，反应概率有明显提高，且反应阈能明显降低， 这说明反应分子的振动能对分子的碰撞反应有重要贡献.而对基态和第一振动激发态时散射 截面的计算，也证明了这一结论.同时，还分别通过计算量子数j，k，m对反应概率的影响， 对该反应的空间取向效应进行了研究，并与H+CH4→CH3+H2反应进行了比较. 关键词： 含时波包 量子散射 反应概率}     

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.     

Induced long-range dipole-field-enhanced antihydrogen formation in the p + Ps(n = 2) --> e(-) + H(n < or = 2) reaction

We report high-precision calculations that correctly include the rearrangement channels by solving the modified Faddeev equations for energies between the Ps(n = 2) and H(n = 3) thresholds, which involve six and eight open channels. We find that 99% of the antihydrogen is formed in H(n = 2). Just above the Ps(n = 2) threshold the S, P, and D partial waves contribute nearly 1400pi(a(2)0) near the maximum. We find evidence that the induced long-range dipole potential is responsible for such a large H formation cross section. The possibility of utilizing this resonance to synthesize low-energy H is discussed.     

Precise determination of the 2s(1/2)-2p(1/2) splitting in very heavy lithiumlike ions utilizing dielectronic recombination

The 2s(1/2)-2p(1/2) energy splittings DeltaE(L) of the lithiumlike ions 19779Au76+, 20882Pb79+, and 23892U89+ have been measured at the Experimental Storage Ring, utilizing low energy dielectronic recombination. The resonance energies in total 41 different 1s(2) 2p(1/2)nl(j(')) (n > or =20) autoionizing Rydberg states populated in the dielectronic capture process have been determined. The 2s(1/2)-->2p(1/2) excitation energies have been obtained by extrapolation of these resonance energies to the associated series limits n--> infinity. The combined analysis of the experimental data for all three ions yields DeltaE(L)=216.134(96) eV for Au76+, 230.650(81) eV for Pb79+, and 280.516(99) eV for U89+.     

用类O原子波函数对H+9团簇的体心立方结构与能量的研究

在单中心球模型近似下,选用类O原子解析函数,用变分法计算了H+9团簇体心立方结构与能量。结果表明当中心氢原子核到顶角氢原子核之间的距离R=1.97a0时,体系能量有一极小值E=-4.376h0(a0=0.529177×10-10m,h0=27.2eV)。这表明H+9团簇的体心立方结构是稳定的结构,H+9团簇是存在的。     

Pr3+:Y2SiO5中的反斯托克斯荧光谱及其对基态Stark分裂能级的确定

掺杂在晶体Y2 SiO5(YSO)中的Pr3 ,运用脉冲激光激发 3H4 → 1 D2 跃迁 ,粒子通过非辐射能量转移从能级 1 D2 转移到能级 3P0 ,测得了对应于 3P0 → 3H4 跃迁的反斯托克斯荧光光谱 ,由此可确定 3H4 的Stark分裂能级以及 3P0 能级的能量高度。与运用激光激发 3H4 → 1 D2 跃迁 ,通过观察 1 D2 → 3H4 斯托克斯荧光光谱确定3H4 的Stark分裂能级方法相比 ,该过程避免了不同晶点位置中 (Crystallographicsite)Pr3 的 1 D2 能级间的能量转移影响 ,从而具有较高的确定性。同时 ,我们观察了反斯托克斯荧光的时间特性     

O(1D)+N2O→NO+NO反应的理论研究

应用三体模型及扩展的LEPS势能面(PES),对初始条件为(Ecol=55 kJ/mol,v=0,j=0)的O(1D)+N2O→NO+NO反应体系进行了准经典轨线(QCT)计算.根据计算结果对体系的势能面及反应机理进行详细的分析和讨论,较全面地研究了此反应体系的动力学特征.     

Observation of a new DsJ meson in B+-->D0D0K+ decays

We report the observation of a new DsJ meson produced in B+-->D0DsJ-->D0D0K+. This state has a mass of M=2708+/-9(-10)(+11) MeV/c2, a width Gamma=108+/-23(-31)(+36) MeV/c2 and a 1- spin-parity. The statistical significance of this observation is 8.4 sigma. The results are based on an analysis of 449 x 10(6) BB events collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider.     

Search for D0-&Dmacr;( 0) mixing

We have studied the "wrong-sign" process D0-->K+pi(-) to search for D0-&Dmacr;( 0) mixing. The data come from 9.0 fb(-1) of e(+)e(-) collisions at sqrt[s] approximately 10 GeV recorded with the CLEO II. V detector. We measure the relative rate of the wrong-sign process D0-->K+pi(-) to the Cabibbo-favored process &Dmacr;( 0)-->K+pi(-) to be R = (0.332(+0.063)(-0.065)+/-0.040)%. We study D0-->K+pi(-) as a function of decay time to distinguish direct doubly Cabibbo-suppressed decay from D0-&Dmacr;( 0) mixing. The amplitudes that describe D0-&Dmacr;( 0) mixing, x(') and y('), are consistent with zero. At the 95% C.L. and without assumptions concerning charge-parity ( CP) violating parameters, we find (1/2)x('2)<0.041% and -5.8%相似文献   

Measurements of the branching fractions for psi(3770)-->D(0)D[over ](0), D+D-, DD[over ], and the resonance parameters of psi(3770) and psi(2S)

We measure the branching fractions for psi(3770)-->D(0)D[over ](0), D+D-, DD[over ], and non-DD[over ] to be (46.7+/-4.7+/-2.3)%, (36.9+/-3.7+/-2.8)%, (83.6+/-7.3+/-4.2)%, and (16.4+/-7.3+/-4.2)%, respectively. The resonance parameters of psi(3770) and psi(2S) are measured to be M_(psi(3770))=3772.2+/-0.7+/-0.3 MeV, Gamma_(psi(3770))(tot)=26.9+/-2.4+/-0.3 MeV, and Gamma_(psi(3770))(ee)=251+/-26+/-11 eV; M_(psi(2S))=3685.5+/-0.0+/-0.3 MeV, Gamma_(psi(2S))(tot)=331+/-58+/-2 keV, and Gamma_(psi(2S))(ee)=2.330+/-0.036+/-0.110 keV. We also measure the light hadron R value to be R(uds)=2.262+/-0.054+/-0.109 in the energy region from 3.660 to 3.872 GeV.     

Observation of a near-threshold D(0)D[over](0)pi(0) enhancement in B-->D(0)D[over](0)pi(0)Kappa decay

We report the first observation of a near-threshold enhancement in the D(0)D[over](0)pi(0) system from B-->D(0)D[over](0)pi(0)Kappa decays using a 414 fb(-1) data sample collected at the Upsilon(4S) resonance. The enhancement peaks at a mass M=3875.2+/-0.7(+0.3)/(-1.6) +/-0.8 MeV/c2 and the branching fraction for events in the peak is B(B-->D(0)D[over](0)pi(0)Kappa)=(1.22+/-0.31(+0.23)/(-0.30))x10(-4). The data were collected with the Belle detector at the KEKB energy-asymmetric e+ e- collider.     

State-to-state dynamics for O(1D)+D2-->OD+D: evidence for a collinear abstraction mechanism

The O(1D)+D2-->OD+D reaction at two different collisional energies, 2.0 and 3.2 kcal/mol, is investigated by using the H(D) Rydberg "tagging" time-of-flight technique. Experimental results in this study indicate that the OD product is clearly more backward scattered relative to the O(1D) beam direction at the collisional energy of 3.2 kcal/mol. The extra backward scattered OD products are mostly in the highly vibrationally excited states (upsilon = 4,5,6), which is typical of a collinear abstraction mechanism. The experimental results in this work also provide a good testing bed for quantitative theoretical investigations of this benchmark system.     

Structural effects on water formation from coadsorbed H + O on Rh(100)

The effect of adsorbate coverage, adsorption sequence and temperature on the structure, composition and reactivity of coadsorbed layers, produced by dissociative adsorption of O₂ and H₂ at 200 K on a Rh(100) surface, has been studied by combined TPD, XPS and LEED measurements. The emphasis is on the impact of the structure and composition of the mixed O + H layers on the synthesis of hydroxyl and water as a result of the O + H surface reaction. The difference in the O 1s binding energies of adsorbed O (529.9 eV) and OH species (530.8 eV) was used as a fingerprint to monitor the formation of the OH species. The H₂O TPD spectra show substantial variations of the desorption temperature range and the amount of water evolved with coadsorbate coverage and structure: from 270 to 350 K and from 0 to 0.08 ML, respectively. It has been found that dense O + H adlayers, where the O coverage is in the range 0.25-0.4 ML, favor the formation of stable OH species. The maximum amount of stable hydroxyl OH species ( 0.16 ML) can be produced by heating of these dense adlayers to 260 K. This results in reordering of the adspecies to form a new O + OH − (2 × 6) structure, where hydroxyls react readily to evolve 0.08 ML of water in a sharp desorption peak at 280 K. The effect of the adlayer density and restructuring on the production of OH and H₂O is discussed.     

D+CD4→CD3+D2反应的量子含时动力学研究

运用半刚体振动转子靶(semirigid vibrating rotor target)模型,利用含时波包法(TDWP method),对反应D+CD4→CD3+D2进行了量子含时动力学研究与计算.反应几率随平动能的变化图象,呈现出显著的量子共振特性.并通过对v=0时,j=0,1,2的反应几率以及j=0时,v=0,1的反应几率的计算,对该反应的空间效应进行了研究与分析.     

Search for rare and forbidden eta(') decays

We have searched for rare and forbidden decays of the eta(') meson in hadronic events at the CLEO II detector. The search is conducted on 4.80 fb(-1) of e(+)e(-) collisions at 10.6 GeV center-of-mass energy at the Cornell Electron Storage Ring. We find no signals, and set 90% confidence level upper limits of their branching fractions: B(eta(')-->e(+)e(-)eta)<2.4x10(-3), B(eta(')-->e(+)e(-)pi(0))<1. 4x10(-3), B(eta(')-->e(+)e(-)gamma)<0.9x10(-3), and B(eta(')-->e&mgr;)<4.7x10(-4). We also fit the matrix element of the eta(')-->pi(+)pi(-)eta Dalitz plot with the parametrization |M|(2) = A|1+alphay|(2), where y is a linear function of the kinetic energy of the eta, and find Re (alpha) = -0.021+/-0.025.