S(1D)+D2反应的立体动力学理论研究

在ab initio 势能面上利用非含时量子反应散射理论研究了S(1D)+D2反应在散射能为22.18 kJ·mol-1时的立体动力学. 计算的微分反应截面呈现弱反对称的前向后向散射, 这一结果与以前的准经典结果和实验结果相一致. 态分辨的极化依赖的微分反应截面和极化参数显示产物极化并非各向异性分布, 这意味着在反应过程中由于势能面上存在一个深势阱从而形成了长寿命的复合物.     

N(4S)+ NO(X2Π)→N2(X3Σg-)+O(3P) 反应的立体动力学研究

采用准经典轨线方法研究了在不同碰撞能下，碰撞反应N(4S)+NO(X2Π)→ N2(X3Σg- )+O(3P)在两个最低势能面3A 和 3A'上产物与反应物之间的矢量相关. 结果表明，对于不同的碰撞能，在两个势能面上反应产物的转动取向展示了不同的特征和趋势. 随着碰撞能的增加，发生在3A 势能面上的反应主要受外平面机理支配，而发生在 3A' 势能面上的反应倾向于受内平面机理支配. 这些差异来自于两个势能面的不同构型.     

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。     

Quasi-classical Trajectory Study of the Intramolecular Isotope Effect in the Reaction O（3p）＋H2/HD

Theoretical studies of the dynamics of the reactions O（3p）＋H2/HD（ν=0, j=0）→OH＋H have been performed with quasi-classical trajectory method （QCT） on an ab initio potential surface for the lowest triplet electronic state of H2O（aA＂）. The QCT-calculated integral cross sections are in good agreement with the earlier time-dependent quantum mechanics results. The state-resolved rotational distributions reveal that the product OH rotational distributions for O＋HD have a preference for populating highly internally excited states compared with the O＋H2 reaction. Distributions of differential cross sections show that directions of scattering are strongly dependent on the choice of quantum state. The polarization dependent generalized differential cross-sections and the distributions were calculated and a pronounced isotopic effect is revealed. The calculated results indicate that the product polarization is very sensitive to the mass factor.     

CH2(X 3B1)自由基与O2的反应

用时间分辨富里叶红外发射谱仪（ＴＲ－ＦＴＩＲＳ）研究了ＣＨ２（Ｘ＾３Ｂ１）自由基与Ｏ２反应的通道及产物的振动动态布居，基电子态自由基ＣＨ２（Ｘ＾３Ｂ１）由３５１ｎｍ紫外激光光解ＣＨ２ＣＯ生成，观测到振动发态反应产物ＣＯ（ｖ≤１０），ＣＯ２（ｖ３≤７）ＯＨ（Ｈ２Ｏ）和Ｈ２ＣＯ的红外发射，证实存在生成Ｈ２ＣＯ的通道，由光谱拟合得到不同时刻ＣＯ（ｖ）和ＣＯ２（ｖ３）的相对振动布居，发现ｖ＝４能级的布居数     

CH2＝CHCl与O(3P)反应的理论研究

用量子化学密度泛函理论和QCISD (Quadratic configuration interaction calculation)方法, 对O(³P)与CH₂CHCl的反应进行了理论研究. 在UB3LYP/6-311＋＋G(d,p), UB3LYP/6-31＋＋G(3df, 3pd)计算水平上, 优化了反应物、产物、中间体和过渡态的几何构型, 并在UQCISD(T)/6-311＋＋G(2df,2pd)水平上计算了单点能量. 为了确证过渡态的真实性, 在UB3LYP/6-311＋＋G(3df,3pd)水平上进行了内禀坐标(IRC)计算和频率分析, 并确定了反应机理. 研究结果表明, 反应主要产物为CH₂CHO和Cl.     

Theoretical study of the stereodynamics of the reactions O(D) + H2, D2 and HD

Calculations of the dynamics of the reactions O(¹D) + H₂ → OH + H, O(¹D) + HD → OH + D, O(¹D) + HD → OD + H and O(¹D) + D₂ → OD + D have been performed using the quasi-classical trajectory (QCT) method with symplectic integration. The theoretical calculations were carried out on the ground state 1A′ potential energy surfaces (PES) by Dobbyn and Knowles. The distributions of the dihedral angle P(_r), the angle between k and j′, P(θ_r), and the product vibrational state are presented. The results show that the intermediate geometrical structures and lifetimes of the reactive collisions play a vital role in these reactions.     

Effects of Single Quantum Rotational Excitation on Reaction of F+D2 at Collision Energies between 44 and 164 cm-1

There is no general picture to describe the influences of reagent rotational excitation on the reaction, which proceeds via the tunnelling mechanism at collision energies far below the reaction barrier. Here we report a crossed beam study on the prototypical reaction of F+D\begin{document}$_2$\end{document}(\begin{document}$v$\end{document}=0, \begin{document}$j$\end{document}=0, 1)\begin{document}$\rightarrow$\end{document}DF(\begin{document}$v'$\end{document})+D at collision energies between 44 and 164 cm\begin{document}$^{-1}$\end{document} with the scheme of multichannel D-atom Rydberg tagging time-of-flight detection. Vibrational state resolved differential cross sections are obtained at \begin{document}$v'$\end{document}=2, 3, 4 levels. The effects of reagent rotational excitation were investigated at an equivalent amount of total energy by precise tuning of translational energies. Compared with translation, the rotation of D\begin{document}$_2$\end{document} is found to be more efficient to promote the title reaction. Profound differences introduced by rotation of D\begin{document}$_2$\end{document} are also observed on the angular distribution and quantum state distribution of DF products. We hope the present work could provide an example for understanding the effects of reagent rotational excitation on the chemical reaction at energies that are much lower than the reaction barrier.     

CH2(X 3B1)自由基与N2O反应的研究

The reaction dynamics of methylene radical CH2(X3B1) with N2O was investigated by Time-Resolved Fourier Transform Infrared Spectroscopy(TR-FTIRS). Pure CH2(X3B1) radicalwas produced via laser photolysis of ketene at 351 nm. Nascent viabrationally excited products CO, NO and HCN were observed. Some reaction pathways which may lead to these products were proposed and a possible reaction mechanism was outlined.     

尿素/H2O2溶液同时脱硫脱硝机理研究

在填料塔上对尿素/H₂O₂溶液同时脱硫脱硝进行了实验研究。结果表明,尿素溶液对SO₂具有很高的去除效率,但对NO_x的去除受到多种因素的影响。实验主要研究了H₂O₂浓度、吸收反应温度、溶液pH值等因素对脱硝效率的影响,并确定了最佳实验条件,在此条件下脱硫脱硝效率分别达到100%和52.6%。同时,采用化学分析法和气相色谱法对尿素溶液同时脱硫脱硝的反应产物进行分析,推导出尿素/H₂O₂溶液同时脱硫脱硝的反应机理和总化学反应方程式。该技术可用于对现有湿法脱硫技术的改造,使其同时具有脱硫脱硝功能。     

Catalytic decomposition of H2O2 on Co3O4 doped with MgO and V2O5

The effects of doping of Co₃O₄with MgO (0.4–6 mol%) and V₂O₅ (0.20–0.75 mol%) on its surface and catalytic properties were investigated using nitrogen adsorption at −196°C and decomposition of H₂O₂ at 30–50°C. Pure and doped samples were prepared by thermal decomposition in air at 500–900°C, of pure basic cobalt carbonate and basic carbonate treated with different proportions of magnesium nitrate and ammonium vanadate. The results revealed that, V₂O₅ doping followed by precalcination at 500–900°C did not much modify the specific surface area of the treated Co₃O₄ solid. Treatment of Co₃O₄ with MgO at 500–900°C resulted in a significant increase in the specific surface area of cobaltic oxide. The catalytic activity in H₂O₂ decomposition, of Co₃O₄ was found to suffer a considerable increase by treatment with MgO. The maximum increase in the catalytic reaction rate constant (k) measured at 40°C on Co₃O₄ due to doping with 3 mol% MgO attained 218, 590 and 275% for the catalysts precalcined at 500, 700 and 900°C, respectively. V₂O₅-doping of Co₃O₄ brought about a significant progressive decrease in its catalytic activity. The maximum decrease in the reaction rate constant measured at 40°C over the 0.75 mol% V₂O₅-doped Co₃O₄ solid attained 68 and 93% for the catalyst samples precalcined at 500 and 900°C, respectively. The doping process did not modify the activation energy of the catalyzed reaction but much modified the concentration of catalytically active constituents without changing their energetic nature. MgO-doping increased the concentration of CO³⁺–CO²⁺ ion pairs and created Mg²⁺–CO³⁺ ion pairs increasing thus the number of active constituents involved in the catalytic decomposition of H₂O₂. V₂O₅-doping exerted an opposite effect via decreasing the number of CO³⁺–CO²⁺ ion pairs besides the possible formation of cobalt vanadate.     

Combination Effect of Cation Vacancies and O2 Adsorption on Ferromagnetism of Na0.5Bi0.5TiO3(100) Surface: ab initio Study

The combination effect of cation vacancies and O₂ adsorption on ferromagnetism of Na_0.5Bi_0.5TiO₃(100) surface is studied by using density functional theory.An ideal Na_0.5Bi_0.5TiO₃(100) surface is non-magnetic and the cation vacancy could induce the magnetism.By comparing the formation energies for Na, Bi and Ti vacancy, the Na vacancy is more stable than the others.Therefore, we focus on the configuration and electric structure for the system of O₂ molecule adsorption on the Na_0.5Bi_0.5TiO₃(100) surface with a Na vacancy.Among the five physisorption configurations we considered, the most likely adsorption position is Na vacancy.The O₂ adsorption enhances the magnetism of the system.The contribution of spin polarization is mainly from the O 2p orbitals.The characteristics of exchange coupling are also calculated, which show that the ferromagnetic coupling is favorable.Compared with the previous calculation results, our calculations could explain the room-temperature ferromagnetism of Na_0.5Bi_0.5TiO₃ nanocrytalline powders more reasonably, because of taking into account adsorbed oxygen and cation vacancies.Moreover, our results also show that adsorption of O₂ molecule as well as introduction of cation vacancies may be a promising approach to improve multiferroic materials.     

Enhanced Water Oxidation Activity on Ni,Co-Doped Fe2O3 (0001) Surface

Fe based oxides are considered as a promising catalyst for the oxygen evolution reaction (OER) due to their low cost and high stability. Here, based on density functional theory calculations, the electrocatalytic behaviors of pure and metal (Ni, Co) doped Fe-terminated Fe₂O₃(0001) are investigated. The potential-limiting step for OER is determined as the formation of O^* by dehydrogenating surface hydroxyl and it is suggested that the doping enhances the catalytic activity of Fe₂O₃(0001) by reducing the free energy change of rate limiting step on doped Ni or Co atom. Especially, the calculated over-potential of Co-doped Fe₂O₃ (0001) surface is about 0.63 eV on Co site, which is comparable with the theoretical over-potential of 0.56 eV for RuO₂.     

3-硝基邻苯二甲酸锆的制备﹑热分解机理及非等温反应动力学

用3-硝基邻苯二甲酸、氢氧化钠和硝酸氧锆为原料, 制备了3-硝基邻苯二甲酸锆, 采用元素分析、X射线荧光衍射和FT-IR对其结构进行了表征. 用TG-DTG以及变温固相原位反应池/傅里叶变换红外光谱(RSFT-IR)联用技术研究了3-硝基邻苯二甲酸锆的热分解机理, 对主分解反应的DTG峰进行了数学处理, 计算得到了动力学参数和动力学方程. 结果表明, 3-硝基邻苯二甲酸锆的分解反应总共有4个阶段, 其中主分解反应发生在第2阶段, 主分解反应的表观活化能Ea与指前因子A分别为158.84 kJ·mol-1和10^9.85 s-1, 主分解阶段的反应机理服从一级Mample法则, 主分解反应的动力学方程为dα/dt=10^9.85(1-α)e^-1.91×10⁴/T.     

Effect of diabatic correlation on the reactions of O(2 3P, 2 1D) with N2 O and CO2

Although correlation diagrams based upon the application of spin and angular momentum conservation have been shown to be a useful device in interpreting the chemistry of electronically excited atoms, experimental observations suggest that a more complete understanding of such chemical processes requires some insight into the electronic structure of the collision complex. In the absence of such information, it is possible to consider the role of diabatic correlations on the energetics of elementary processes with a view toward analyzing the behavior of the reactants along the reaction coordinate. Here, the aeronomically interesting reactions of ground state and electronically excited oxygen atoms with N₂ O and CO₂ are analyzed and the effects of low-lying molecular excited states on the reactivity of these molecules assessed.     

MOF derived Co3O4/N-doped carbon nanotubes hybrids as efficient catalysts for sensitive detection of H2O2 and glucose

Developing enzyme-free sensors with high sensitivity and selectivity for H2O2 and glucose is highly desirable for biological science.Especially,it is attractive to exploit noble-metal-free nanomaterials with large surface area and good conductivity as highly active and selective catalysts for molecular detection in enzyme-free sensors.Herein,we successfully fabricate hollow frameworks of Co3O4/N-doped carbon nanotubes(Co3O4/NCNTs)hybrids by the pyrolysis of metal-organic frameworks followed by calcination in the air.The as-prepared novel hollow Co3O4/NCNTs hybrids exhibit excellent electrochemical performance for H2O2 reduction in neutral solutions and glucose oxidation in alkaline solutions.As sensor electrode,the Co3O4/NCNTs show excellent non-enzymatic sensing ability towards H2O2 response with a sensitivity of 87.40μA(mmol/L)^-1 cm^-2,a linear range of 5.00μmol/L-11.00 mmol/L,and a detection limitation of 1μmol/L in H2O2 detection,and a good glucose detection performance with 5μmol/L.These excellent electrochemical performances endow the hollow Co3O4/NCNTs as promising alternative to enzymes in the biological applications.     

TPR studies on steam reforming of 2-propanol on Rh/Al2O3, Ru/Al2O3 and Pd/Al2O3

Reaction pathways for steam reforming of 2-propanol (isopropyl alcohol, IPA) on Rh/Al₂O₃, Ru/Al₂O₃ and Pd/Al₂O₃ have been studied by temperature-programmed reactions (TPRs) of IPA and acetone in the presence of steam. The results of TPRs suggest that that of IPA on Rh/Al₂O₃ and Ru/Al₂O₃ proceeds via acetone, while the steam reforming of IPA on Pd/Al₂O₃ takes place via propene from acetone. This revised version was published online in August 2006 with corrections to the Cover Date.     

CIONO2与O(3P)的反应机理

采用密度泛函方法Ｂ３ＬＹＰ／６－３１Ｇ＾＊研究了反应Ｏ（＾３Ｐ）＋ＣｌＯＮＯ２→ＣｌＯ＋ＮＯ３反应Ｏ（＾３Ｐ）＋ＣｌＯＮＯ２→Ｏ２＋ＣｌＯＮＯ的反应机。该结果与大部分实验者的推论是一致的,对于后一反应,其两种反应途径的活化势垒较为相近,表明两种反应途径均是可能的。     

Dynamics of reactions of O(3P) atoms with CS,CS2 and OCS

The reactions of CS(X ¹Σ⁺), CS₂(X ¹Σ⁺_g) and OCS(X ¹Σ⁺) with O(³P) were studied at 298 K by means of a CO laser resonance absorption technique. The CO(ν) population distribution produced from the reaction O(³P) + CS(X ¹Σ⁺) studied in a quartz flash photolysis tube (λ>/ 200 nm) is similar to distributions observed previously for ν> 7. For ν < 7 an energetically colder vibrational population was observed which is attributed to the reaction of O(³P) atoms with undissociated CS₂(X ¹Σ⁺_g). Subsequent experiments carried out in a Pyrex flash photolysis tube (λ>/ 300 nm) in which the O(³P) + CS₂(X ¹Σ⁺_g) reaction is the only one which can occur confirmed that the colder population observed is attributable to this process. The branching ratio for the reaction channel O(³P) + CS₂(X ¹Σ⁺_g) → CO(X ¹Σ⁺) + S₂(³Σ^?_g) has been measured. We find that 1.4 ± 0.2% of the O + CS₂ reaction proceeds through this channel, and that the rate constant for this reaction channel is, k = 3.5 (±0.5) × 10¹⁰ cm³/mole s. Isotope labeled experiments using ¹⁸O atoms show that the O(³P) + OCS(X ¹Σ⁺) reaction takes place by a direct stripping mechanism, wherein CO(ν) is produced exclusively from the parent OCS molecule. The CO(ν) formed in this reaction carries about 9% of the total available energy.     

Kinetics of O(1D) interactions with the atmospheric gases N2, N2O,H2O,H2, CO2, and O3

Rate coefficients for collisional removal of O(¹D) by six atmospheric gases have been measured by monitoring the appearance of O(³P) following photolytic production of O(¹D). The measured values, k_M±2σ, in units of 10^?11 cm^?3 molecule ^?1 s^?1 are k_O3 = 22.8±2.3, k_N2 = 2.52 ± 0.25, k_CO2 = 10.4 ± 1.0,k_H2O 195± 2.0, k_N2O = 11.7 ± 1.2, and k_H2, = 11.8±1.2.