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Density functional theory and ab initio calculations have been used to determine structures and stabilities of the protonated aromatics species AH^+ and AH2^2+ (A=pyrrole, furan). Possible mechanisms and relative energetics for protonation of pyrrole and furan by H3O^+ and AH^+ in the gas phase have been explored. Calculations show that the Cα-protonated species was the most stable structure for AH^+, and the protonated AH^+ might accommodate the second proton to yield AH2^2+ if the free proton was available. The gas-phase H3O^+ could protonate pyrrole and furan with significant exothermiCity and almost without barrier. The proton transfer from AH4^+ to pyrrole and furan has a barrier ranging from 33.5 to 39.3 kJ/mol in the gas phase. 相似文献
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基于第一性原理, 系统地研究了Ben (n=1~3)对B12团簇结构的调控. 结果表明: 团簇BeB12全局极小结构为Cs对称性准平面结构, 而Be2B12和Be3B12最稳定的结构均为笼状结构, 对称性分别为Cs和C2v. 随着Ben (n=1~3)原子数的增加, 团簇B12由准平面结构过渡到笼状结构, 且Be倾向内嵌在B12笼状结构表面的B7或B8单元环中, 通过离子和共价作用形成稳定Be&B7和Be&B8单元, 从而稳定笼状结构. 自然键轨道(NBO)分析表明, 团簇Cs BeB12, Cs Be2B12, C2v Be3B12内部存在电子转移情况, Be原子2s轨道上失去电子, Be—B键主要以离子作用为主, 同时也存在共价作用. 成键分析显示Cs Be2B12和C2v Be3B12的π键遵循球状芳香性2(n+1)2 (n=1)电子计数规则, 表明该团簇具有球状芳香性. 预测了三个结构的红外和拉曼光谱, 为以后的合成实验和数据表征提供了理论基础. 相似文献
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从球状泡群气泡动力学方程出发, 考虑泡群间次级声辐射的影响, 得到了声场中两泡群共同存在时气泡振动的动力学方程, 并以此为基础探讨声波驱动下双泡群振动系统的共振响应特征. 由于泡群间气泡间的相互作用, 系统存在低频共振和高频共振现象, 两不同共振频率的数值与泡群内气泡的本征频率相关. 泡群内气泡的本征频率又受到初始半径、泡群大小和泡群内气泡数量的影响. 气泡自由振动和驱动声波的耦合激起泡群内气泡的受迫振动, 气泡初始半径、气泡数密度和驱动声波频率等都会影响泡群内气泡的振动幅值和初相位.
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气泡群
共振
声响应
超声空化 相似文献
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采用甚高频等离子体增强化学气相沉积技术成功地制备了不同硅烷浓度和辉光功率条件下的微晶硅电池.电池的J-V测试结果表明:在实验的硅烷浓度和功率范围内,随硅烷浓度的降低和功率的加大,对应电池的开路电压逐渐变小;硅烷浓度的不同对电池的短路电流密 度有很大的影响,但功率的影响在实验研究的范围内不是很显著.对于微晶硅电池,N层最好 是非晶硅,这是因为一方面可以降低对电流的横向收集效应,另一方面也降低了电池的漏电概率,提高了电池的填充因子.
关键词:
微晶硅太阳电池
甚高频等离子体增强化学气相沉积 相似文献
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We consider an iterative scheme for finding a common element of the set of solutions of a pseudomonotone, Lipschitz-continuous
variational inequality problem and the set of common fixed points of N nonexpansive mappings. The proposed iterative method combines two well-known schemes: extragradient and approximate proximal
methods. We derive a necessary and sufficient condition for weak convergence of the sequences generated by the proposed scheme. 相似文献
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Convergence and certain control conditions for hybrid viscosity approximation methods 总被引:1,自引:0,他引:1
Very recently, Yao, Chen and Yao [20] proposed a hybrid viscosity approximation method, which combines the viscosity approximation method and the Mann iteration method. Under the convergence of one parameter sequence to zero, they derived a strong convergence theorem in a uniformly smooth Banach space. In this paper, under the convergence of no parameter sequence to zero, we prove the strong convergence of the sequence generated by their method to a fixed point of a nonexpansive mapping, which solves a variational inequality. An appropriate example such that all conditions of this result are satisfied and their condition βn→0 is not satisfied is provided. Furthermore, we also give a weak convergence theorem for their method involving a nonexpansive mapping in a Hilbert space. 相似文献