甲胺分子的紫外光解离动力学实验研究

在280—287.5 nm区域内,通过实验测定共振增强多光子电离-时间飞行质谱、碎片离子的分质量激发谱以及光强指数等对甲胺分子的光解离通道进行了研究.实验结果证实甲胺分子在单光子能量范围内存在一个电子排斥态,主要的光解离过程为甲胺分子共振吸收1个光子到达该电子排斥态后解离成中性碎片,然后是中性碎片经多光子共振电离形成碎片离子和碎片离子的进一步解离.     

两种烷基碘化物分子C—I键解离的从头计算

分别采用多组态自洽场方法和二阶多组态准简并微扰论方法,计算了烷基碘化物分子CF₃I和C₂H₂F₃I沿C—I键的绝热势能曲线和垂直激发能. 结果发现,这两种分子的低激发态均为排斥态;基态的解离能分别为2.473eV和2.835eV,其中前者与实验结果符合较好. 关键词： 烷基碘化物分子 解离能 势能曲线     

The location of excess electrons on H2O/TiO2(110) surface and its role in the surface reactions

Excess electrons play a key role in many of the properties of Titanium dioxide (TiO₂). Understanding their behaviour is important for improving the performance of TiO₂ in energy-related applications. Here, we describe a DFT + U study of the locations of the unpaired electron (UPE) on rutile TiO₂(110) (R-TiO₂(110)) surface and H₂O/R-TiO₂(110) surface. Our results show that the subsurface are preferred with R-TiO₂(110) surface. In contrast to previous studies, we find that the UPE tends to migrate to the surface H₂O-Ti_5c (the five-coordinated titanium (Ti_5c) at surface with H₂O adsorption) with the increasing of H₂O coverage and UPE concentration. In addition, we have shown that the UPE plays an important role in the O-H bond dissociation and other important elementary reactions in photo-catalytic H₂O dissociation on R-TiO₂(110) such as H, OH and H₂ desorption. Specifically, it enhances the O-H bond dissociation, as well as H and H₂ desorption from bridging hydroxyl and Ti_5c-OH (the Ti_5c with OH adsorption), but hinders the OH and H desorption from Ti_5c. We believe our results afford a further understanding of the adsorbent dependent UPE migration, and the role of UPE in the surface reactions.     

外电场作用下BrCl分子的物理特性与光谱

采用HF （Hartree-Fock）方法,在6-31+G（d,p）基组水平上优化不同外电场（0~0.035 a.u.）下氯化溴分子的基态稳定构型,在此基础上计算氯化溴分子的分子结构、偶极矩、分子总能量、分子键长、分子电荷分布、分子能隙、红外光谱及解离势能面等.结果表明：随着Z轴（平行于Br-Cl连线）方向外电场的增加（0~0.035 a.u.）,分子总能量先小幅度增加后又降低,键长先减小后增大,分子偶极矩先减小后单调增加,原子电荷分布递增,分子能隙逐渐减小,分子红外光谱先蓝移后红移.通过对解离势能面的计算分析发现,强度为0.045 a.u.的外电场使得Br-Cl键断裂而降解,该结果对氯化溴进行电场降解提供参考依据.     

GaH(X1Σ+)自由基的光谱常数与分子常数研究

采用内收缩多参考组态相互作用(MRCI)方法和系列相关一致基aug-cc-pVnZ对GaH (X1Σ+)自由基的光谱性质进行了研究. 通过与实验结果的比较, 发现在aug-cc-pV5Z基组、且考虑相对论修正时得到的De, Re和ωe与实验结果较为一致. 在这一基组下对GaH(X1Σ+)自由基的势能曲线进行了计算、并将计算结果拟合成了Murrell-Sorbie函数, 由此得到的光谱常数(ωeχe, αe和 Be)也与实验结果较为相符. 以得到的解析势能函数为基础, 通过求解双原子分子核运动的径向Schrödinger方程, 找到了J = 0时该自由基存在的全部27个振动态. 针对每一振动态, 还计算了它的振动能级、经典转折点、转动惯量和离心畸变常数, 文中的大部分分子常数均属首次报导.     

Density functional theory study of formaldehyde adsorption and decomposition on Co-doped defective CeO_2(110) surface

Formaldehyde as an air pollutant to adverse health effects for humanity has been getting attention. The adsorption and dissociation of formaldehyde(HCHO) on the Co_xCe_(1-x_O_(2-δ)(110) surface were investigated by the density functional theory(DFT) calculations. We calculated the oxygen vacancy formation energy as the function of its site around dopant Co in detail. The results showed that Co doping was accompanied by compensating oxygen hole spontaneous formation.The adsorption configurations and bindings of HCHO at different locations on the Co_xCe_(1-x)O_2(110) were presented.Four possible pathways of oxidation of formaldehyde on the catalytic surface were explored. The results suggested that formaldehyde dissociation at different adsorption sites on the doped CeO_2(110) — first forming dioxymethylene(CH_2O_2)intermediate, and then decomposing into H_2O, H_2, CO_2, and CO molecules. It was found that the presence of cobalt and oxygen vacancy significantly prompted the surface activity of CeO_2.     

Entropic destruction of heavy quarkonium in a rotating hot and dense medium from holography

Previous studies have indicated that the peak of the quarkonium entropy at the deconfinement transition can be related to the entropic force, which would induce the dissociation of heavy quarkonium. In this study, we investigated the entropic force in a rotating hot and dense medium using AdS/CFT correspondence. It was found that the inclusion of angular velocity increases the entropic force, thus enhancing quarkonium dissociation, while chemical potential has the same effect. The results imply that the quarkonium dissociates easier in rotating medium compared with the static case.     

烃类化合物碳氢键解离焓的密度泛函理论研究

通过比较10种密度泛函方法对烃类化合物碳氢键解离焓的计算精度, 发现新型密度泛函BMK方法具有最高的计算精度. 利用该方法计算了包含饱和链烃,、不饱和链烃、脂环烃和芳香烃在内的172个烃类化合物的碳氢键解离焓,计算均方根误差仅为7.95 kJ•mol^－1, 线性拟合常数为0.985. 通过自然键轨道法分析发现, 烃类物质的碳氢键解离焓与母体的碳氢键杂化轨道成分p%, 自由基奇电子轨道杂化成分p%及自由基的自旋密度三个参数之间存在较好的定量关系. 此外, 饱和链烷烃及不饱和链烃的碳氢键解离焓与碳氢键键长之间也存在较好的线性关系.     

3，5－二溴－4－氨基苯基荧光酮的离解及与钼显色反应的研究

用分光光度法研究了２，３，７－三羟基－９－（３，５－二溴－４－氨基）苯基荧光酮的离解平衡和离解常数；以其为显色剂，进行了钼（ＶＩ）的分光光度法研究，在０．２～０．８ｍｏｌ·Ｌ－１ＨＣｌ溶液中，ＣＴＭＡＢ存在下，显色剂与Ｍｏ（ＶＩ）生成灵敏的红色三元配合物，ε５３０＝１．５６×１０５Ｌ·ｍｏｌ－１·ｃｍ－１，用于测定钢中的钼，结果满意．     

Pressure dissociation of dense hydrogen

The self-consistent fluid variational model （SFVM） has been used to describe the pressure dissociation of dense hydrogen at high temperatures. This paper focuses on a mixture of hydrogen atoms and molecules and is devoted to the study of the phenomenon of pressure dissociation at finite temperatures. The equation of state and dissociation degree have been calculated from the free energy functions in the range of temperature 2000-10,000K and density 0.02-1.0g/cm^3, which can be compared with other approaches and experiments. The pressure dissociation is found to occur in higher density range, while temperature dissociation is a more gradual effect.