Cl＋HD反应产物的极化与态分析

利用准经典轨线理论，在BW2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BW2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BW2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BW2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。     

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     

Cl+CH4反应的含时量子动力学研究

基于新的势能面,运用半刚性振动转子靶(SVRT)模型和含时波包法对Cl+CH4→HCl+CH3反应体系进行了计算,给出了反应过程中体系的振动、转动及空间立体效应对该反应的反应几率和反应阈能的影响,并计算了基态的总散射截面和热速率常数.     

使用态-态分辨的量子波包方法对Li+HF/DF反应的研究

使用基于反应物坐标的含时量子波包方法,在APW势能面上,计算了碰撞能在0～0.25 eV范围的Li+HF/DF(v=0,j=0,1)反应的积分和微分截面．同时也计算了初始态选择的反应速率常数．计算结果表明,Li+DF和Li+HF反应产物分布基本类似,只是前者产物转动激发态稍微多些．反应物的转动激发对于Li+DF反应影响很小．这两个反应的微分截面都是前向散射为主的,特别是在碰撞能较高时候．产物振转态分辨的积分截面和后向散射随碰撞能而呈现的振荡现象,可以用来指认Li+HF反应中的共振态．Li+HF的反应速率常数在100～300 K几乎不变,而Li+DF的反应速率常数则增长了10倍左右．Li+HF的反应几率和积分截面和以前报道的结果总体符合较好,差别应该是计算收敛性更好所致．     

O(3P)+CD4反应的含时波包动力学计算

基于Modified Jordan和Gilbert的势能面,运用SVRT(semirigid vibrating rotor target)模型和TDWP(Time-Dependent Wave Packet)方法,对O(3P)+CD4反应体系进行了含时量子动力学计算,给出了该体系的总反应几率,散射截面和热速率常数等结果.通过对j=0时, v=0,1的反应几率的计算,看出D-CD3的振动激发,极大地提高了反应几率,而反应阈能明显降低,说明反应分子的振动能对分子的碰撞反应有重要贡献. 而对于v=0时j=0,1,2,3的反应几率的计算,得出转动量子数j的增大,也会使反应几率有较大的提高,但反应阈能基本不变.     

O(3P)+CD4反应的含时波包动力学计算

基于Modified Jordan和Gilbert的势能面,运用SVRT(semirigid vibrating rotor target)模型和TDWP(Time-Dependent Wave Packet)方法,对O(3P)+CD4反应体系进行了含时量子动力学计算,给出了该体系的总反应几率,散射截面和热速率常数等结果.通过对j=0时, v=0,1的反应几率的计算,看出D-CD3的振动激发,极大地提高了反应几率,而反应阈能明显降低,说明反应分子的振动能对分子的碰撞反应有重要贡献. 而对于v=0时j=0,1,2,3的反应几率的计算,得出转动量子数j的增大,也会使反应几率有较大的提高,但反应阈能基本不变.     

F+H2化学反应中的Feshbach共振之研究

化学反应共振态研究是化学动力学研究的重要前沿课题,对于理解基元化学反应的机理有重要的意义.本文中介绍了最近在这一研究方向的重大进展.通过对F＋H2化学反应的全量子态分辨的分子束反应散射实验研究,观测到了F＋H2中反应中明显的反应共振现象.通过高精度的全量子散射动力学研究,发现这一共振现象是由两个Feshbach共振态所引起的,而且这两个Feshbach共振态之间在前向散射有明显的量子干涉效应.这项研究工作使得我们对这一重要基元反应中的化学反应共振态研究向前迈进了一大步。     

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.     

Cl+CHD3(v1=1)反应中的成对动态学:侦测激光波长的效应

用交叉分子束试验探讨氯原子与C?H 键激发的CHD3化学反应，并用(2+1)共振多光子电离及离子影像法来侦测CD3基态生成物．发现所得的影像对电离光子的波长极为敏感．这表明，与基态反应比较，C?H激发反应较易产生转动激发的CD3．实验结果也证明CD3D的转动与HCl的振动激发有相反的关联性．     

于串珠分子动力学的Cl+XCl→XCl+Cl(X=H，D，Mu)反应的速率系数和动力学同位素效应研究

本文用串珠分子动力学计算典型的重-轻-重反应Cl+XCl→XCl+Cl(X=H,D,Mu)的热速率系数和动力学同位素效应. 对于Cl+HCl反应,串珠分子动力学方法计算得到的结果与实验值之间的高度一致性为串珠分子动力学理论的准确性提供了有力的证据. 串珠分子动力学结果也与其他理论方法的计算结果相一致,包括正则变分过渡态理论和量子动力学方法. Cl+MuCl反应在过渡态附近存在势能双峰,留下了自由能阱,它来自于势能面峰值处反应系统的模式软化. 同时,如此明显的自由能阱表明存在反应共振. 对于Cl+DCl反应,与实验值相比,串珠分子动力学速率系数再次给出了非常准确的结果. 唯一的例外是在312.5 K的温度下,串珠分子动力学速率系数和其他理论方法计算得到的结果彼此接近,却略低于实验值,表明误差可能源于实验测量或本文使用的势能面不够精确.     

Luminescence of F + and F centers in YAlO3

In YAlO₃ crystals grown in vacuum or reduced by annealing at low oxygen pressure, the luminescence of F centers in the band at 420 nm, with τ=30 ms at 9 K, excited in the bands at 212 and 242 nm, as well as the luminescence of F ⁺ centers in the band at 355 nm, with τ=2.7 ns, excited in the main band at 220 nm and weaker bands at 190 and 288 nm, was detected. On the basis of the results obtained and data in the literature, the behavior of the emission of F ⁺ and F centers in oxides of the Al₂O₃-Y₂O₃ system is analyzed on the example of the compounds α-Al₂O₃, YAlO₃, and Y₃Al₅O₁₂. The role of antisite defects in the stabilization of F-like luminescence and absorption centers in multisublattice oxides is discussed.     

Low-lying states of F2 +

Calculated potential energy curves for the 13 lowest electronic states of F₂ ⁺ are presented. Nine of the potential curves are found to possess substantial binding energies, while two others also display shallow, stable minima. The ordering, binding energies, relative equilibrium separations and vibrational frequencies of these curves should be of utility in helping to assign the large number of observed vibration-rotation lines in the electronic emission spectrum of F₂ ⁺. The calculated curves are in reasonable agreement with the available data on the two experimentally observed states.     

Resonance-mediated chemical reaction: F+HD-->HF+D

Conclusive evidence is presented for the existence of a reactive resonance in the F+HD reaction. In a molecular beam experiment, the resonance appears in the integral cross section as a distinct steplike feature, while in the differential cross section it is manifested as sharply varying forward-backward peaks in the product distribution. A detailed analysis of the quantum dynamics establishes that a reactive resonance localized in the transition-state region is responsible for these remarkable observations. At collision energies below 1 kcal/mol, the reaction proceeds almost exclusively through resonant tunneling with very little contribution from the more conventional direct mechanism.     

F L V a + a and F L F color centers in lithium fluoride crystals

Using optical spectroscopy and X-ray diffraction analysis, the nature of defects in γ-irradiated lithium fluoride crystals is found, mechanisms of their formation are proposed, and the absorption bands at 385 (F _L F centers) and 506 nm (F _L V _a ⁺ centers) are interpreted.     

The F+ center in reactor-irradiated aluminum oxide

A point-ion calculation has been performed for the F⁺ center in α-Al₂O₃ (one electron in an O^2? vacancy). Optical transitions are predicted at 2·26, 3·39 and 5·15 eV. Contact hyperfine interactions with the two nearest pairs of Al³⁺ ions are calculated to be 151 and 39 G. Single crystals of α-Al₂O₃ were reactor-irradiated up to doses of 10²⁰ fast neutrons per cm², and studied by electron spin resonance (ESR). A broad ESR spectrum with 13 resolved components at g=2·0029±0·0005 was interpreted as the interaction of an unpaired electron with two pairs of Al³⁺ nuclei with hyperfine constants of 49·2 and 13·5 G. These values are in the same ratio as the values calculated for the F⁺ center, to which this ESR spectrum is attributed. The discrepancy of a factor of three is typical of point-ion calculations. The optical absorption spectrum for heavily-irradiated samples is not available for comparison with calculated transition energies.     

Photoconductivity of strontium oxide containing F+ centres

Photoconductivity has been measured from the F⁺ absorption band in electron and proton irradiated SrO. The measurements were made over the spectral range from 2 to 4 eV and over the temperature range from 65 to 180 K. The photocurrent excited in the F⁺ band appears to be carried by electrons and has a thermal activation energy of about 0.10 eV.     

Vector correlations in the F + HD reaction

A theoretical study of the orientation of product rotational angular momenta for two chemical reaction channels: F + HD(ν _r = 0, j _r = 0) → HF(ν, j) + D and F + HD(ν _r = 0, j _r = 0) → DF(ν, j) + H at a E _coll = 78.54 meV collision energy was performed. Angular momentum orientation was described on the basis of irreducible tensor operators (state multipoles) expressed through anisotropy transfer coefficients, which contained quantum-mechanical scattering T matrices determined on the basis of exact solutions to quantum scattering equations obtained using the hyperquantization algorithm. The possibility of the existence of substantial orientation of the angular momentum of reaction products j in the direction perpendicular to the scattering plane was demonstrated. The dependences of differential reaction cross sections and state multi-poles on the ν and j quantum numbers were calculated and analyzed. A experimental scheme based on the multiphoton ionization method was suggested. The scheme can be used to detect predicted reaction product angular momentum orientation.     

Ion bombardment-induced charge state effects CaO single crystals: F+ and F centers

The effects of heavy-and light-ion bombardment on defect formation in CaO have been investigated by UV-absorption spectroscopy and volume measurements. While 500 keV Ar or Ca implantation produces only F⁺ centers, 240 keVH produces both F⁺ and F centers at a F⁺ to F ratio of 5.6 to 1. On the other hand, when an argon implanted sample is subsequently bombarded with hydrogen, about 30% of the F⁺ centers anneal during 1 ×10¹⁴ H/cm²; at higher H fluences, new F⁺ and F centers are produced. An effect of energy partition between ionization and nuclear/atomic collision processes for the incident ions on the charge state of the resulting defect is thus clearly demonstrated.

The formation and annealing of these defects are accompanied by volume changes in the ion implanted surface layer which can be monitored in sltu with a cantilever beam technique. The measurements show volume expansion of the order of 1.5% following 10¹⁶ 500 keV Ar implantation; subsequent implantation of 10¹⁸ 240 keV H compacts the previously expanded material by 25 %. These results are in qualitative agreement with the optical data and seem to indicate that volume changes are associated with the formation and annealing of F⁺ centers.     

F3+和Ne4+离子的光电离截面的理论计算

利用R矩阵方法计算了F³⁺和Ne⁴⁺离子的基态2s²2p²(³P)和激发态2s²2p² (¹D,¹S),2s2p³ (⁵S^o)的分波光电离截面、总光电离截面,分析辨认出了这些离子在自光电离过 关键词： 3+离子和Ne⁴⁺离子')" href="#">F³⁺离子和Ne⁴⁺离子 光电离 自电离共振 R矩阵')" href="#">R矩阵