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1.
在20种不同纯有机溶剂中,研究了5a-雄甾烷-3,17-二酮C3位和C17位羰基的红外光谱.将其羰基伸缩振动频率分别与经验溶剂参数如溶剂接受数AN、Brownstein的溶剂参数S和Schleyer线性自由能方程参数G值进行了相关分析.结果表明,C3位C=O在一元溶剂体系中出现2种谱带,而C17位C=O则出现3种谱带.羰基伸缩振动频率位移与AN值、G值具有较好的线性相关性,而在非醇溶剂中与S值线性相关较差.采用简单化合物丙酮分别对溶剂硝基苯、乙腈、二氯甲烷和氯仿的S值进行修正,并将复杂甾酮化合物5a-雄甾烷-3,17-二酮的羰基红外频率与S修正值进行线性分析,相关性良好.  相似文献   

2.
王小燕  何清  刘清 《光谱实验室》2011,(6):3163-3168
在20种不同纯有机溶剂中,研究了5α-雄甾烷-3,17-二酮C3位和C17位羰基的红外光谱。将其羰基伸缩振动频率分别与经验溶剂参数如溶剂接受数AN、Brownstein的溶剂参数S和Schleyer线性自由能方程参数G值进行了相关分析。结果表明,C3位C=O在一元溶剂体系中出现2种谱带,而C17位C=O则出现3种谱带。羰基伸缩振动频率位移与AN值、G值具有较好的线性相关性,而在非醇溶剂中与S值线性相关较差。采用简单化合物丙酮分别对溶剂硝基苯、乙腈、二氯甲烷和氯仿的S值进行修正,并将复杂甾酮化合物5α-雄甾烷-3,17-二酮的羰基红外频率与S修正值进行线性分析,相关性良好。  相似文献   

3.
苯与铂化学吸附作用及其溶剂效应的量子化学研究   总被引:1,自引:0,他引:1  
采用Gaussian98程序密度泛函方法全优化计算了考虑水溶剂效应下苯与铂化学吸附作用的位能曲线,得到的位能曲线呈单调下降,苯与铂的吸附是自发过程.计算得到无水和有水溶剂作用时的吸附作用能分别为-149.6535和-202.1635kJ/mol;有水溶剂作用时吸附作用能被降低,展示出明显的水溶剂效应.计算还发现,铂可在苯环上发生吸附转移,在无水和有水溶剂效应下,铂转移的活化能分别为61.2537和70.8356kJ/mol.  相似文献   

4.
测量了丙酮在16种溶剂中C=O键的伸缩振动拉曼光谱,并且在Gaussian03程序下采用自恰反应场方法(SCRF)对丙酮在各种溶剂中的拉曼光谱进行了理论计算.用三种溶剂模型的电子给体-受体模型、Kirkwood模型和自恰反应场模型对实验结果进行了分析比较,结果表明Gutmann提出的电子给体-受体模型与实验结果符合的最好,而自恰反应场理论结果要好于Kirkwood模型.通过对三种模型的机理进行分析,得出给体一受体模型在解释电负性比较强的分子键振动光谱比较好,自恰反应场模型不但考虑了介电常数ε,而且考虑了分子大小、构型等因素的影响,模型复杂,计算量比较大,但是因为考虑的因素比较多,所以与实验结果也符合的比较好,而Kirkwood模型的主要参数为ε,模型简单,计算简便,能大致反映频移的趋势,说明介电常数是影响频移的一个主要因素.  相似文献   

5.
苯硝化反应中电子转移反应重组能的计算   总被引:5,自引:0,他引:5       下载免费PDF全文
提出了重组能的量子化学算法 ,在用CISD/6 31G基组水平上 ,得到苯硝化反应中反应物及过渡态的结构 .并计算了各自交换电子转移反应以及交叉电子转移反应的重组能 ,同实验重组能进行了比较 .计算用了Gaus sian 94程序 .从重组能的角度分析了苯硝化反应 .结果表明 ,对于NO2 + +NO2 →NO2 +NO2 + 的自交换电子转移反应 ,重组能较大 ,结论为 :在芳烃硝化反应中 ,存在以NO2 + 为氧化剂的电子转移步骤的可能性很小 ,而从动力学的角度上 ,用NO+ 作反应的氧化剂更有可能 .  相似文献   

6.
对一类以双酚A为连接链,9,10-二甲氧基蒽为电子给体,带不同取代基的苯为电子受体的给体-受体体系的光致电子转移反应的重组能进行了理论计算研究,获得与实验值接近的结果,说明所用的理论计算方法具有可行性。  相似文献   

7.
测量了丙酮在16种溶剂中CO键的伸缩振动拉曼光谱,并且在Gaussian03程序下采用自恰反应场方法(SCRF)对丙酮在各种溶剂中的拉曼光谱进行了理论计算。用三种溶剂模型的电子给体-受体模型、Kirkwood模型和自恰反应场模型对实验结果进行了分析比较,结果表明Gutmann提出的电子给体-受体模型与实验结果符合的最好,而自恰反应场理论结果要好于Kirkwood模型。通过对三种模型的机理进行分析,得出给体-受体模型在解释电负性比较强的分子键振动光谱比较好,自恰反应场模型不但考虑了介电常数ε,而且考虑了分子大小、构型等因素的影响,模型复杂,计算量比较大,但是因为考虑的因素比较多,所以与实验结果也符合的比较好,而Kirkwood模型的主要参数为ε,模型简单,计算简便,能大致反映频移的趋势,说明介电常数是影响频移的一个主要因素。  相似文献   

8.
使用密度泛函理论B3LYP方法,对两种薁磺酰胺席夫碱衍生物的分子结构、红外光谱、电子吸收光谱及热力学性质进行计算研究,并基于Tomasi的极化统一场模型(PCM)讨论电子吸收光谱的溶剂效应. 结果表明,红外光谱计算值与实验值吻合,电子吸收光谱都是π-π*跃迁,溶剂及溶剂极性大小对最低能量吸收波长无影响. 酚羟基的引入增大席夫碱的共轭体系,有利于提高分子的生物活性. 298 K时,两种衍生物的 分别为5544.3, 5304.6 kJ•mol-1, 分别为20548.7, 20331.2 kJ•mol-1, 分别为857.5, 881.1 J•mol-1•K-1.  相似文献   

9.
段鹤  陈效双  孙立忠  周孝好  陆卫 《物理学报》2005,54(11):5293-5300
基于第一性原理全电子势线性缀加平面波方法(FPLAPW),计算了闪锌矿结构半导体材料ZnTe,CdTe的能带结构.结合闪锌矿对称化合物的有效质量近似理论,对第一性原理的计算结果进行拟合后,得到了ZnTe,CdTe在带隙附近的电子结构.此外还讨论了晶体场分裂能、自旋-轨道相互作用的分裂能和电子、空穴的有效质量及相应的Luttinger参数,结果与实验值相符合. 关键词: FLAPW 电子结构 有效质量  相似文献   

10.
实验测量了1.7v0-4.2v0(v0为玻尔速度,v0=2.19×108 cm/s)的C3+与He,Ne,Ar原子碰撞过程中单电子转移绝对截面.将实验结果与多体经典轨道蒙特卡罗模拟计算结果做了比较,发现测量结果与多体经典轨道蒙特卡罗模拟计算结果在趋势上相符.当入射离子速度在1.7v0-2.0v0时,因多体经典轨道蒙特卡罗方法计算时不能考虑多电子关联态俘获和极化效应的影响,实验值大于计算值.当入射离子速度在2.2v0-4.2v0时,由于被俘获电子对入射离子的不完全屏蔽,加上电子间的动态关联及有效电荷的影响,实验结果先与多体经典轨道蒙特卡罗计算结果符合很好,而后逐渐大于计算值.此外,还根据转移电离与单电子俘获的截面比简单分析了转移电离机制.  相似文献   

11.
In this paper, inner-sphere electron transfer reactions in a solvent are studied in the framework of multidimensional transition state theory. It is demonstrated that the preexponential factor essentially depends upon the interaction with the inner-sphere vibrational mode, increasing the rate of electron transfer as much as one order of magnitude. The prefactor is shown to be strongly dependent on the frequency of this vibration. At high frequencies the rate constant increases with the reorganization energy of this inner-sphere mode while at small frequencies, electron transfer is inhibited. Estimations of inner mode reorganization energies have been performed for system where it is necessary to account nonequilibrium solvent relaxation. Finally it is shown that the equilibrium approximation fails when the reaction is close to an activationless regime.  相似文献   

12.
In this paper, we investigate the electron transfer (ET) in donor-acceptor model. The Langevin equation with random forces is used. The oscillations of the primary states observed in experimental data have been shown with this approach. And other features on the dependence of the rate of ET on temperature, free energy, and reorganization energy have also been clearly shown.  相似文献   

13.
The gyrotron with an electrically insulated collector has been manufactured and tested. The 60% output efficiency is obtained for the Collector Potential Depression (CPD) operation regime. The results of the numerical simulation of the electron energy spectrum in the collector region of the second-harmonic technological 24 GHz gyrotron are presented. It is shown, that the minimal electron beam energy is about 20% of the initial value and that the gyrotron cavity should be expanded to achieve the highest output efficiency of the gyrotron with energy recovery. The highest experimental decelerating voltage is in good agreement with the calculation of the electron energy spectrum.  相似文献   

14.
Results of a quantum-chemical study of the effect of relative orientation of chromophores and solvent on energy transfer in bichromophore systems are presented. The results of theoretical calculations and the experimental data were found to be inconsistent with the prediction of the Förster theory relative to the effect of the orientation factor on the efficiency of energy transfer. It is shown that the effect of solvent on energy transfer is similar to the effect of a connecting bridge in bichromophore molecules. An interpretation of theoretical and experimental results is presented.  相似文献   

15.
The ability of the multichannel stochastic model to adequately describe the basic features of the kinetics of thermal electron transfer is demonstrated. It is shown that the solution-controlled regime can be realized in the normal Marcus region, whereas it is almost completely suppressed in the inverted region by the reorganization of high-frequency vibrational modes. The continuous transition between the two regions in the neighborhood of the activationless is quantitatively described. It is found that the dynamic properties of the solvent manifest themselves not only in the dependence of the electron transfer rate on the medium relaxation time τ L , but also in the free energy gap law, shifting the position of the maximum effective rate constant to higher reaction exergonicities. This shift depends on the longitudinal relaxation time of the medium. In slow solvents, the maximum rate constant of electron transfer can exceed 1/τ L by several orders of magnitude.  相似文献   

16.
束小建  陈基忠 《光学学报》1991,11(5):25-432
本文采用基于单粒子理论的CAGFEL程序,对中国科学院上海光学精密机械研究所(简称上海光机所)喇曼自由电子激光器的近期实验结果进行了数值模拟,计算表明,当电子能量E_e=0.5MeV,能散度△γ/γ=6%和发射度ξ=0.06(π)rad·cm时,器件的峰值功率高达24MW,对应的辐射增长率为120dB/m,效率为6.1%。  相似文献   

17.
In this paper, the electron transfer reactions in the microwave field are studied. A classical theory is developed for a mix of reagents and polar frequency-dispersive and lossy solvent filling vessels excited by microwaves. These reactors are described by a system of non-linear partial self-consistent differential equations for non-stationary microwave field, heat and liquid dynamics, and chemical molecular kinetics. A particular solution of this system is considered for the isothermic electron-transfer reactions in the microwave field varying its frequency with the calculation of the normalised Marcus rate coefficient. It is found that for the small normalised reaction free energy, the chemical reactions are supported by microwaves in a wide frequency band with an increased value of the exponent in the Marcus rate coefficient. At higher values of this energy, these reactions are driven only by conventional microwave heating. The restrictions for the given theory are reviewed, and further experimental and semi-classical and quantum-mechanical studies are found essential for practical applications of these findings.  相似文献   

18.
Spectroscopic and electrochemical properties of two fullerene(C60)-phenothiazine(PH) linked compounds with different spacer chain length have been compared in benzonitrile (polar solvent) and in benzene (non-polar solvent). Transient absorption and fluorescence spectra indicated that photoinduced intramolecular electron transfer occurred in benzonitrile, but not in benzene. The results are due to solvent effect on energy levels of the photogenerated biradical. The driving forces for the electron transfer were determined by measuring the redox potentials of the C60 and PH moieties. Thermodynamic parameters for the electron transfer processes were evaluated and compared. In benzonitrile, the lifetime of the photo-generated biradical was very long, in spite of being around the top region in Marcus theory. The decay rate of the biradicals was retarded in the presence of magnetic fields. The decay rate constant decreased quickly with increasing the magnetic field and became constant above about 0.2 T. The magnetic field effects verified that the triplet biradical was generated by the intramolecular electron transfer from PH to the triplet excited state of C60. The long lifetime is most probably ascribed to the spin multiplicities of the biradical.  相似文献   

19.
The intramolecular electron transfer on several 1,3‐dinitrobenzene radical anions with different substituents on position 5 was studied by electron paramagnetic resonance and optical spectroscopies in MeCN. The radical anions are all charge‐localized mixed valence species, as is common for meta‐substituted dinitrobenzenes. Rate constants for the electron transfer reaction were obtained by the Marcus–Hush analysis of the intervalence optical bands assuming quartic‐augmented energy surfaces and solvent‐controlled dynamics. These calculated rate constants match quite well the experimental ones obtained by simulation of the electron paramagnetic resonance spectra, which rules out bridge‐reduced states as intermediates in the reaction path and confirms the superexchange mechanism. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

20.
Non-equilibrium energy transfer between electron and lattice sub-systems due to short-pulse heating is formulated and the closed form solution for electron and lattice site temperatures is presented. The electron kinetic theory approach is incorporated to formulate non-equilibrium energy transfer in the electron and lattice sub-systems. The method of Lie point symmetries is used in the exact solution of governing energy equation. In the analysis, the volumetric heat source, representing the laser heating pulse, and surface heat source, corresponding to short thermal contact of the surface, are incorporated and the analytical solutions for each heating source are presented. Electron temperature distribution obtained from the closed form solution is compared with its counterpart predicted from the numerical simulation. It is found that the results obtained from the closed form agree well with electron temperature predictions obtained from numerical simulation.  相似文献   

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