查询词典 electron pair

Next HOMO or HOMO-1 for the radical cations calculated by the ab initio 3-21+G^* method, and the atom-pair interaction energy determined by NMDO calculation, it is shown that when n is equal to or largey than 3 in the bridge chain (CH2)n for bicyclo diamine radical cations, the bridgehead nitrogen atoms form a weak N, N'-three-electron σ-bond through space.

通过比较这些阳离子几何构型，HOMO和NHOMO(即NextHOMO和HOMO-1)，和由MNDO计算确定的原子对作用能，表明当二氮双环游离基阳离子的桥链(CH2)n的n≥3时，桥头氮原子通过空间相互用用形成了一个弱的N，N'-三电子σ键。

The structural and photocatalytic properties of TiO〓 as well as surface acidity were greatly improved by sulfation. SO〓〓/TiO〓 solid superacid with Hammett constant Ho less than -12.14 was prepared by treating the TiO〓 with 1.0mol. L〓 sulfuric acid solution and then calcining at 450℃ for 3h. When compared to unmodified TiO〓, the SO〓〓/TiO〓 superacid catalyst exhibited higher anatase content, smaller crystal size, higher specific surface area, centralized pore size distribution, and the blue-shifted band edge of uv-vis adsorption spectra. Furthermore, the SO〓〓/TiO〓 superacid also showed excellent reaction activity and stability for CH〓Br photocatalytic decomposition even under the moist reaction conditions. The apparent quantum efficiency of SO〓〓/TiO〓 was 10 times of that of TiO〓 catalyst for the photocatalytic degradation of bromomethane. Therefore, the SO〓〓/TiO〓 superacid catalyst is promising for practical application in environmental remediation.It was found that both L and B acid sites exist on SO〓〓/TiO〓 photocatalyst while only L acid sites on TiO〓 photocatalyst. On the basis of experimental results, the synergistic model of superacidic centers was proposed for SO〓〓/TiO〓 photocatalyst to explain the photocatalytic behavior and the mechanism of superacidifing effects, assuming that the adjacent L and B acid sites induced by SO〓〓 comprise cooperatively the superacidic center on superacid photocatalyst. The group cooperation of the superacidic center could strengthen the surface acidity, increase surface acid sites and the adsorbtion of O〓, promote separation of photogenerated electron-hole pair, enhance the interfacial transfer of charges and reversibility of water adsorption. Consequently the excellent photocatalytic activity, reaction stability and resistibility to humidity of SO〓〓/TiO〓 superacid photocatalyst may attributed to the group cooperated effect of the superacidic center on the photocatalyst.

研究结果表明：SO〓〓与TiO〓表面的结合为螯合式双配位结构；TiO〓光催化剂表面经H〓SO〓浸渍处理后，提高了表面酸性，改善了催化剂结构和光催化性能，当H〓SO〓浸渍浓度为1.0mol.L〓、烧结温度为450℃时，可制得SO〓〓/TiO〓超强酸催化剂(H〓＜-12.14)，其结构和光催化活性得到明显改善，与TiO〓相比，SO〓〓/TiO〓光催化剂的锐钛矿含量高、晶粒小、BET比表面积大、孔径分布集中、光谱吸收边蓝移，具有优异的光催化氧化活性、稳定性及抗湿性能，光催化降解溴代甲烷的表观量子效率比TiO〓催化剂提高了一个数量级，是一种有实际应用前景的高效光催化剂；由此提出了SO〓〓/TiO〓超强酸催化剂表面集团协同作用的超强酸中心模型，认为在SO〓〓/TiO〓超强酸催化剂表面，由SO〓〓诱导的相邻L酸中心和B酸中心组成了集团协同作用的超强酸中心，其集团协同作用显著地增强了催化剂表面酸性、增大了表面酸量及O〓吸附量、促进了光生电子和空穴的分离及界面电荷转移，具有可逆吸附水的性能，是SO〓〓/TiO〓超强酸催化剂具有优异的光催化氧化活性、很好的活性稳定性及抗湿性能的重要原因。

The apparent quantum efficiency of SO〓〓/TiO〓 was 10 times of that of TiO〓 catalyst for the photocatalytic degradation of bromomethane. Therefore, the SO〓〓/TiO〓 superacid catalyst is promising for practical application in environmental remediation.It was found that both L and B acid sites exist on SO〓〓/TiO〓 photocatalyst while only L acid sites on TiO〓 photocatalyst. On the basis of experimental results, the synergistic model of superacidic centers was proposed for SO〓〓/TiO〓 photocatalyst to explain the photocatalytic behavior and the mechanism of superacidifing effects, assuming that the adjacent L and B acid sites induced by SO〓〓 comprise cooperatively the superacidic center on superacid photocatalyst. The group cooperation of the superacidic center could strengthen the surface acidity, increase surface acid sites and the adsorbtion of O〓, promote separation of photogenerated electron-hole pair, enhance the interfacial transfer of charges and reversibility of water adsorption. Consequently the excellent photocatalytic activity, reaction stability and resistibility to humidity of SO〓〓/TiO〓 superacid photocatalyst may attributed to the group cooperated effect of the superacidic center on the photocatalyst.

研究结果表明：SO〓〓与TiO〓表面的结合为螯合式双配位结构；TiO〓光催化剂表面经H〓SO〓浸渍处理后，提高了表面酸性，改善了催化剂结构和光催化性能，当H〓SO〓浸渍浓度为1.0mol.L〓、烧结温度为450℃时，可制得SO〓〓/TiO〓超强酸催化剂(H〓＜-12.14)，其结构和光催化活性得到明显改善，与TiO〓相比，SO〓〓/TiO〓光催化剂的锐钛矿含量高、晶粒小、BET比表面积大、孔径分布集中、光谱吸收边蓝移，具有优异的光催化氧化活性、稳定性及抗湿性能，光催化降解溴代甲烷的表观量子效率比TiO〓催化剂提高了一个数量级，是一种有实际应用前景的高效光催化剂；由此提出了SO〓〓/TiO〓超强酸催化剂表面集团协同作用的超强酸中心模型，认为在SO〓〓/TiO〓超强酸催化剂表面，由SO〓〓诱导的相邻L酸中心和B酸中心组成了集团协同作用的超强酸中心，其集团协同作用显著地增强了催化剂表面酸性、增大了表面酸量及O〓吸附量、促进了光生电子和空穴的分离及界面电荷转移，具有可逆吸附水的性能，是SO〓〓/TiO〓超强酸催化剂具有优异的光催化氧化活性、很好的活性稳定性及抗湿性能的重要原因。

Reaction mechenism between heteropoly acid and organic matter is generation of electron-hole pair and producing of three radical such as.

杂多酸与有机物反应的机理主要是电子-空穴对的产生和。

However, the photoactivity of normal TiO_2 nanoparticles do not suffice the requirement of the practical application because of its wide band gap and high combination ratio of electron-hole pair.

但是普通纳米TiO_2带隙较宽、光生电子-空穴对的复合几率高，使其活性还不能满足实际应用的需求。

At Hcy/Au electrode, there were electrocatalytic responses of DA and E with ΔEp 57.5mV and 63.5mV, respectively. The standard rate constants k〓 were calculated as 2.1×10〓 cm s〓 and 1.6×10〓 cm s〓 corresponding to DA and E. The electron transfer number n〓=1 was achieved, which revealed that the 2e transfer of DA and E is not completed by one step at the electrode. Because AA also displayed electrocatalytic behavior at Hcy/Au electrode, DA and E can be determined in presence of AA.At Hcy/Au electrode, a pair of very stable and well-defined redox waves of Mb were obtained.

在Hcy/Au电极上分别得到多巴胺、肾上腺素的一对可逆的氧化还原波，求出两者的电极反应速率常数分别为2.2×10〓cm s〓和1.6×10〓cm s〓，推导出在两者的电极反应过程中均存在一个自由基并且它的形成决定了整个电极反应的速度；由于抗坏血酸在此电极上也具有电催化响应，可以在抗坏血酸存在下对多巴胺和肾上腺素进行测定。

Neutralino dark matter is thus expected to pair-annihilate in very dense regions, producing high-energy particles such as pions and electron-positron pairs and high-energy photons.

因此，在非常致密的区域中性超对称粒子可以成对湮灭，产生高能的粒子，如介子，正负电子对还有高能的光子。

Based on a brief introduction of the important Radical Pair Mechanism of Chemically Induced Dynamic Electron Polarization, a series of CIDEP spectra originated from RPM, partially or entirely, were recorded and analyzed in this dissertation.

论文在对CIDEP中的一个重要机理——RPM机理的模型阐述的基础上，对多种具有RPM机理的体系进行了实验测量，并对实验谱图进行了分析，最后从理论上对RPM的极化强度进行了计算。

The charge distribution result shows that the carbon is easy to get electron, and the nitrogen with lone pair electrons in the amino group is the electrophilic reaction site.

电荷分布方面，三聚氰胺分子上的碳原子易得电子为亲核试剂进攻点，而胺基上的氮原子因含孤对电子是亲电反应中心。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。