虚阴极时间相关行为的单荷电层分析

用格林函数法计算圆柱腔中单荷电层的空间电荷场,分析在圆柱腔漂移管中的虚阴极时间相关行为。求出在非相对论情形下极限电荷q_L的表达式,对不同电荷值、荷电层的位置与速度随时间变化关系进行数值计算分析。给出了虚阴极直观的物理图象。     

铜族金属与完整及氮掺杂石墨烯的相互作用

基于广义梯度密度泛函理论和周期平板模型,研究了铜族金属单原子和双原子簇与完整及氮掺杂石墨烯的结合情况.结果表明,氮掺杂后石墨烯的电子结构特性由半金属性变为金属性;铜族金属在完整及石墨型氮掺杂石墨烯上的吸附较弱,结合能约为0.5eV,而在吡啶型氮掺杂和吡咯型氮掺杂石墨烯上有较强的化学吸附,结合能一般大于1eV;吡咯型氮掺杂后的构型不稳定,金属原子及簇与包含该结构的石墨烯衬底作用时会使其向吡啶型氮掺杂转变,并最终得到基于吡啶型氮掺杂的稳定吸附构型.Mulliken电荷布居分析显示,吸附在吡啶型氮掺杂石墨烯上的金属单原子与金属双原子簇带电性质相反.态密度及轨道分析表明,Cu与吡啶型氮掺杂石墨烯空位处留有悬挂键的三个原子成键,而Au与其中两个C原子成键.     

Novel non-covalent interactions involved with the Al13M cluster (M = Li,Na, K,Cu, Ag,Au)

The complexes of Al₁₃M cluster (M = Li, Na, K, Cu, Ag, Au) and Lewis bases NH₃, H₂O, C₆H₆, and HLi have been predicted and characterised. The results showed that the cluster Al₁₃M forms the alkali-bonding or coinage metal-bonding interaction through M with these Lewis bases. These complexes exhibit some similarities and differences in the structures, properties, and nature with conventional molecules. The formation of these interactions has a negligible or small effect on the structures of Al₁₃M. This study combines the cluster Al₁₃M with non-covalent interactions, which is of great importance in supramolecular chemistry.     

Localized surface plasmon resonance enhanced blue light-emission of polyfluorene copolymer

Polyfluorene-based blue light-emitting devices suffer from the shortcomings of low stability, drastic loss of quantum yield and poor color purity. To find out the solution, we use silver nanoparticles for enhancement of photoluminescence of polyfluorene copolymer (PCFOz) through localized surface plasmon resonance (LSPR) coupling effect. The photoluminescence from PCFOz can be concentrated down to nanoscale, realizing a high spatial selectivity of the fluorescence enhancement process. PL emission of conjugated polymer is blueshifted about 8 nm from the peak emission of 433 nm for the neat PCFOz film to around 425 nm for the Ag/PCFOz composite film. The full width at half maximum of PCFOz is reduced from 88 to 60 nm. Absorbance spectra and time resolved photoluminescence measurements further demonstrate that both absorption intensity and recombination rate of PCFOz increase due to strong LSPR-excitons coupling. Optical properties of such plasmon-enhanced organic light emitters were also studied by temperature-dependent PL spectroscopy from 10 to 200 K. In comparison with bare PCFOz, the LSPR induced emission enhancement ratio significantly increases with increasing temperature. These results are believed to be important for the development of highly efficient blue organic light-emitting devices based on all-solution processing.     

Hydrogen bonding involved with superhalogen MX2NY: its influence on the structure and stability of the superhalogen

The hydrogen-bonded complexes formed of superhalogen MX₂NY (M?=?Li, Na; N?=?Be, Mg; X, Y?=?F, Cl, Br) and hydrogen fluoride have been investigated with quantum chemical calculations at the MP2/aug-cc-pVDZ and M06-2X/aug-cc-pVDZ levels of theory. It was shown that the M06-2X method presents similar results with the MP2 method. The strength of hydrogen bonding is related with the nature of metal and halogen atoms. The metal with greater electron-donating ability leads to a stronger hydrogen bond, whereas the halogen with bigger electron-withdrawing ability also results in the stronger hydrogen bond. The presence of hydrogen bond has a small effect on the structures of the superhalogen and contributes to the stability of the superhalogen.     

乙烯在FeO(100)面吸附的理论研究

运用密度泛函理论中的广义梯度近似的PW91方法结合周期性平板模型,探讨了乙烯分子在FeO(100)面上不同吸附位的平行吸附行为.结果表明,乙烯在hollow位上吸附最稳定,与底物的两个Fc原子形成双σ键,吸附能为86.8 kJ/mol.吸附前后的态密度、电荷布居、轨道成分和振动频率的分析结果表明,在吸附过程中,乙烯的π电子向底物转移,同时Fe将3d轨道的电子反馈给乙烯的反键π轨道,乙烯C的杂化方式由印sp2部分转化为sp3.     

水分子在立方ZrO2（110）面吸附与解离的密度泛函理论研究

采用密度泛函理论巾的广义梯度近似(GGA)的PW91方法结合周期性平板模型,研究了H2O,OH和O在立方ZrO2(110)面上不同吸附位的吸附.结果表明,在bridge位H2O以垂直底物甲面氢原子向上模式吸附在立方ZrO2(110)而时发牛解离形成表面羟基,吸附能为150.5 kJ/mo1.而在top位H2O以垂直底物平面氢原子向下模式吸附为物理吸附,吸附能为14.8 kJ/mo1.OH和O在立方ZrO2(110)面的最佳吸附位是top位,其吸附能分别为241.5和209.1 kJ/mo1.同时分析了Mulliken布居、态密度和伸缩振动频率.     

一种高阻抗,低束流虚阴极器件的研制

基于虚阴极微波发生器的原理,设计一种特殊的高阻抗、低束流Vircator的实验装置,并结合理论研究对该实验系统的各种参量进行了数值计算与分析,实验测试结果与理论设计计算吻合,在3cm频段获得的输出功率≥20MW。     

Preparation and Application of Magnetically Recoverable Cationic Exchanger Support on Monodisperse Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> Nanoparticles

A magnetically recoverable cationic exchanger has been effectively prepared through immobilized chloroacetic acid (CA) onto the Fe₃O₄ nanoparticles. The magnetic nanoparticles (MNPs) were synthesized by a coprecipitation method in an aqueous system. The MNPs were modified with sodium silicate and chloroacetic acid (CA), thus endowed these nanoparticles with strong magnetism and good dispersion. The physicochemical properties of the cationic exchange materials were characterized with Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). The magnetic properties of the cationic exchange materials were analyzed by a vibrating sample magnetometer (VSM). The content of ions was measured by atomic absorption spectrophotometric method. The prepared cationic exchange nanoparticles display an excellent magnetic property with a saturation magnetization value of 26.58 emu/g and the prepared exchanger possess considerable thermal stability, which indicating a great potential application in heavy metal ion wastewater treatment. In this experiment, the exchange capacity of lead ion was 3.4 mmol g^–1, And the maximum lead removal rate is up to 73.85%.     

苯在Ag(100)表面吸附的周期性密度泛函理论研究

 采用量子化学中的密度泛函理论结合平板周期模型方法,研究了苯在Ag(100)面上的吸附方式和相对稳定性. 通过对不同吸附位置的吸附能和几何构型参数的比较发现,苯在Ag(100)表面的吸附属于较强的化学作用,穴位吸附的稳定性优于桥位,顶位吸附最不稳定. 吸附的苯分子的平衡构型发生扭曲, C-C键有较大程度的伸长; C-H键的键长基本不变,但是偏离苯环平面,并背离Ag(100)表面. 在吸附过程中,电子由苯向表面银原子转移. 本文给出了详细的轨道示意图和电荷布居分析,并且与相关的实验和理论研究结果进行了比较.