溴化苄及其阳离子红外光谱的理论研究

利用密度泛函理论（DFT）在B3LYP/6-311G++（d,p）水平上对溴化苄分子进行了结构优化和频率计算,得到了该分子的稳定构型和全部振动模式。计算得到的几何参数通过与苯分子的实验值相比,发现理论值与其相吻合;理论计算和实验测得的红外光谱数据的比较分析表明,理论计算与实验测量结果符合得较好,并对其振动模式进行了归属。最后,在B3LYP/6-311G++（d,p）水平上计算得到了溴化苄阳离子的红外光谱,并与溴化苄进行了比较,计算表明电离对振动偶极距产生了较大影响。     

溴化苄及其阳离子红外光谱的理论研究

利用密度泛函理论（DFT）在B3LYP/6-311G++（d,p）水平上对溴化苄分子进行了结构优化和频率计算,得到了该分子的稳定构型和全部振动模式。计算得到的几何参数通过与苯分子的实验值相比,发现理论值与其相吻合;理论计算和实验测得的红外光谱数据的比较分析表明,理论计算与实验测量结果符合得较好,并对其振动模式进行了归属。最后,在B3LYP/6-311G++（d,p）水平上计算得到了溴化苄阳离子的红外光谱,并与溴化苄进行了比较,计算表明电离对振动偶极距产生了较大影响。     

对氯氟苯S_0、S_1和D_0态的实验与理论研究（英文）

本文采用共振增强多光子电离和慢电子速度成像技术研究了对氯氟苯(p-ClFPh)在中性第一激发态和阳离子基态下的几何结构和振动频率.给出了对氯氟苯S_0态的红外光谱和S_1←S_0跃迁的吸收光谱.基于单色、双色共振增强双光子电离技术,得到了对氯氟苯的跃迁激发能是36302±4 cm~(-1).通过阈值电离测量,外推得到对氯氟苯的绝热电离能为72937±8 cm~(-1).此外,通过Franck-Condon模拟,确定了S_1和D_0态的主要振动模式,并分析了对氯氟苯分子S_0S_1和S_1D_0跃迁过程中的Duschinsky振动模式混合效应.     

人参皂甙Re结构与振动光谱的密度泛函理论研究

利用密度泛函理论方法(B3LYP/6-31G)对人参中的有效成分人参皂甙Re(Ginsenoside Re)的两种异构体20-(R)-Re和20-(S)-Re的平衡几何构型进行了优化,对其振动频率进行了计算, 二者的空间结构有明显的不同,振动光谱也有一定的区别。这些变化是因为20号手性碳4个取代基空间取向不同导致两种异构体的堆积方式不同,从而导致红外和拉曼光谱峰位以及峰形变化。根据理论上计算出来的红外强度与拉曼活性及相对应的频率,对实验得到的红外光谱和拉曼光谱进行了指认,发现计算值1 541, 1 456和1 424 cm-1等谱峰,可作为区分两种异构体的特征谱峰。计算的振动频率同拉曼光谱的实验结果较好吻合。这一结果表明,振动光谱可以用来对人参有效成分进行鉴定。     

对氯氟苯S0, S1和D0态的实验与理论研究

本文采用共振增强多光子电离和慢电子速度成像技术研究了对氯氟苯(p-ClFPh)在中性第一激发态和阳离子基态下的几何结构和振动频率. 给出了对氯氟苯S₀态的红外光谱和S₁←S₀跃迁的吸收光谱. 基于单色、双色共振增强双光子电离技术,得到了对氯氟苯的跃迁激发能是36302±4 cm^-1. 通过阈值电离测量,外推得到对氯氟苯的绝热电离能为72937±8 cm^-1. 此外,通过Franck-Condon模拟,确定了S₁和D₀态的主要振动模式,并分析了对氯氟苯分子S₀&S₁和S₁&D₀跃迁过程中的Duschinsky振动模式混合效应.     

电子与氢及其同位素分子碰撞的非解离性电离截面研究

在边界等离子体中, 氢及其同位素分子与高能电子碰撞可发生电离反应. 对于尚无可利用的氢及其同位素分子的电子碰撞非解离性电离反应截面, 基于莫尔斯函数、弗兰克-康登原理, 采用半经典的Gryzinski方法进行了计算. 得到反应截面随电子能量的变化情况以及振动能级对反应截面的影响. 计算结果表明分子的振动激发对电离反应有着显著影响.     

7-羟基香豆素红外光谱的密度泛函理论研究

红外光谱是化合物结构鉴定的重要信息来源,对天然有机药物的分子结构及其生物活性研究意义重大。而随着理论计算方法更加合理、计算精度不断提高,理论计算在红外光谱模拟、振动模式归属指认等方面优势更加明显,对红外光谱解析等实验研究具有重要参考价值。本研究利用密度泛函理论(density functional theory, DFT)/B3LYP方法,在6-311G(d,p)基组水平对7-羟基香豆素进行了几何结构优化和红外光谱计算,得到稳定结构及全部振动模式。计算结果显示7-羟基香豆素红外光谱吸收峰主要分布于波数3 700～3 500,3 150～3 000,1 750～1 400,1 400～1 000,1 000～50 cm-1几个区域。除波数3 700～3 500,3 150～3 000 cm-1范围内振动相对独立,分别归属为O—H伸缩振动和芳环C—H伸缩振动外,其他几个区域均较为复杂,谱峰不同程度由多个振动模式叠加而成。最后,根据振动模式理论及振动图像分析,对所有振动模式进行了详细指认。并通过线性回归方法,利用相关系数值r研究了7-羟基香豆素红外光谱主要吸收峰波数理论计算值和实验数据的相关性。结果表明,计算值和实验值基本吻合,相关系数值等于0.998 5,相关性较好;采用密度泛函理论在该基组水平对7-羟基香豆素红外光谱的理论计算较为可靠。     

亮氨酸与异亮氨酸的低频集体振动的太赫兹光谱研究

太赫兹(THz)波是指频率在0.1～10 THz频段的电磁波。太赫兹光谱技术不同于以往的检测手段,可以用于检测氨基酸同分异构体,反映物质的分子结构和构型,对食品安全和药品药性控制有着重要的意义。亮氨酸与异亮氨酸属于同系的同分异构体,它们具有近似的分子结构,但物理化学性质有很大的差别。生物大分子的太赫兹吸收与其分子间氢键和分子内氢键的振动和转动能级相关的偶极跃迁有关,可以利用分子偶极跃迁进行生物分子的指纹识别。采用太赫兹时域光谱(THz-TDS)和傅里叶红外光谱(FTIR),对亮氨酸和异亮氨酸进行了测量。在中红外波段亮氨酸与异亮氨酸的吸收光谱几乎完全重叠,而在太赫兹频波段可以观察到它们的光谱存在明显差异,因此太赫兹光谱能够作为快速准确鉴别这两种物质的方法。采用密度泛函理论(DFT)对亮氨酸和异亮氨酸的低频集体振动模式进行理论模拟,并对其太赫兹光谱进行研究和讨论。通过比较实验和理论结果,计算得到的峰位与实验结果可以互相印证。     

太赫兹时域光谱技术探测亮氨酸和异亮氨酸的低频集体吸收谱

氨基酸同分异构体的检测对食品安全和药品药性控制有重要意义。亮氨酸与异亮氨酸是同系的同分异构体,它们具有相似的化学结构,但物理化学性质有很大的差别。区分氨基酸同分异构体的常见的检测方法常用气相色谱、液相色谱、毛细管电泳、液质联用、色质联用等。但上述方法样品需要进行衍生化处理,很难快速、高效、无损的检测检测氨基酸的同分异构体。太赫兹(Terahertz,THz)波是指频率在0.1~10THz频段的电磁辐射,该技术可以反映物质的结构和构型。生物大分子的太赫兹吸收与其分子间氢键的振动和转动能级有关的偶极跃迁相关,可以利用分子偶极跃迁进行指纹识别。本文研究了太赫兹时域光谱技术在室温条件下的亮氨酸和异亮氨酸样品的光谱特征。结果表明亮氨酸和异亮氨酸样品在这个波段存在不同的光谱响应,可以用来探测分子的结构和振动情况从而区分结构差异小的同分异构体。本文还利用B3LYP杂化密度泛函的自洽场晶体轨道法对亮氨酸和异亮氨酸周期性结构进行了理论研究和光谱计算。通过比较实验和理论结果,并对获得的频谱进行了解析,计算得到的峰位与实验结果能够互相印证。     

基于UV-FAIMS的挥发性氯代苯检测方法

挥发性氯代苯是一类典型的环境有机污染物,离子迁移谱(IMS)是一种大气压下基于离子迁移率的快速现场检测技术。采用自制的真空紫外离子源-高场不对称波形离子迁移谱(UV-FAIMS),对空气中氯苯、对二氯苯、邻二氯苯、间二氯苯进行了检测。获取了不同分离电压条件下的CV-I谱图,并以此得到了四种物质的CV-DV指纹谱图。在指纹谱图支持下,设计了对二氯苯、邻二氯苯、间二氯苯三种同分异构体最优化分离检测参数,结果表明在800和1 000 V的分离电压下,通过特征峰的选取,在补偿电压(CV)为20.4 V(DV=800 V),3.2 V (DV=800 V)和11.9 V (DV=1 000 V)处三种物质的混合物可以得到有效的分离识别。研究了流速对谱图峰位置和峰形的影响,得到不同流速下灵敏度和识别精度关系,为优化流量的选取提供了依据。在特征识别前提下考察了DV=450 V条件下,CV=4.3 V的对二氯苯特征峰的UV-FAIMS检测限,结果高达0.05 mg·m-3。该研究为卤代苯等多同分异构体苯类环境污染物的快速高精度检测提供了一种方法参考。     

Variation of Dipole Moment Function of O-H Bond of t-Butanol with the Nature of Solvent and Its Temperature

The intermolecular influence on dipole moment function is evaluated for O-H bond of t-butanol in different nonpolar solvents at temperatures ranging from 10° to 60°C employing IR band intensities of fundamental and first overtone bands. Two sets of dipole moment derivatives have been calculated corresponding to – and +- combinations of the transition moment matrix elements R₁₀ and R₂₀, the values for ++ and -+ combinations are equal in magnitude to those for - and +- combinations, respectively and opposite in signs. In general the dipole moment derivatives increase on lowering the temperature as well as with increasing molecular interactions with the solvent molecules. Dipole moment plots with dimensionless coordinate ξ [=(r-r_e)/r_e, where r and r_e are internuclear distances during vibration and at equilibrium, respectively] are reported for various systems considered. It is found that for +- combination the dipole moment maximum shifts to higher internuclear distances when polarisation of the solute molecules is increased by lowering of temperature or increase in molecular interactions between solute and solvent molecules. A reverse trend is observed for – combination.- The OH band of t-butanol vapor has been measured.     

Dipole moment studies of the structure of 2,6-diaryl-4-piperidones

Several 2,6-diaryl-4-piperidones were prepared. The configuration and conformation of these piperidones are discussed from the measured values of dipole moments. The influence of substitution on the molecular interactions of these compounds are studied. The results are interpreted in relation to their structure conformation and the charge distribution in groups like N–H and CO. A correlation between the dipole moment values of these compounds with the IR spectral shift and intensities is also attempted.     

IR Spectra and dipole moment function of the H2S molecule in the gas and liquid phases

The IR spectra of H₂S molecules in the gas and liquid phases and in solutions of liquefied noble gases are experimentally studied over a wide range of frequencies, including the regions of second- and third-order transitions. Based on experimental data on the parameters of the effective dipole moment, the first, second, and third derivatives of the dipole moment of the H₂S molecule with respect to the normal coordinates are recovered. The values of the first derivatives with respect to the coordinates associated with the stretching vibration are abnormally small in comparison with the higher-order derivatives. The change in the dipole moment of the molecule H₂S under the influence of the intermolecular forces on gas-liquid transition is examined. The observed anomalously large (more than 200-fold) increase in the absolute intensity of the fundamental stretching vibration band ν_str cannot be accounted for by abnormally strong intermolecular interaction forces. The increase in the absolute intensity of the ν_str band is associated with abnormally small first derivatives of the dipole moment of the gas-phase molecule. The effect of the intermolecular forces on the dipole moment is compared to that for the H₂O molecule.     

矿物流场冲击与极性吸附作用产物的红外光谱研究

 在马赫数M≥3冲击作用下和偶极矩大于或等于2.0极性分子的表面吸附作用条件下,对比了7种重要矿物微粒的红外吸收光谱特征及其变化,分析了7种矿物微粒的力学-结构效应以及表面基团的转化过程。     

Force and torque on a sphere with electric dipole moment moving in a dielectric fluid in the presence of a uniform magnetic field

The torque exerted by a magnetic field on a sphere with permanent electric dipole moment moving steadily in a dielectric fluid is calculated to lowest order in the dipole moment. Hence the force exerted on a steadily rotating sphere with electric dipole moment is found by Onsager symmetry. The modification from the vacuum values of torque and force depends only on the slip parameter and the static dielectric constant of the fluid. It is suggested that for a macroscopic ferro electric sphere the calculated effects could be measured experimentally without great difficulty.     

Influence of molecular structure of squaraine dyes on their aggregation in aqueous solutions

The influence of the molecular structure of several squaraine dyes on their aggregation in aqueous solutions and its spectral manifestation were studied. The results are analyzed using quantum-chemical modeling. It is shown that a transverse dipole moment in squaraine molecules contributes to aggregation with an antiparallel orientation of the molecules whereas a longitudinal dipole moment leads to formation of J-type aggregation with a longitudinal orientation of the molecules. In some instances both aggregate types are present in the solution over a wide concentration range.     

Density Functional Theory Analysis of Ground State and Evaluation of Transition Probability Parameters for Carbon Mono-Fluoride Molecule

Journal of Applied Spectroscopy - In view of astrophysical application, the ground state molecular parameters such as bond length, dipole moment, rotational constant, harmonic frequency, IR...     

Band intensities in the IR spectra of metal carbonyl complexes,Ni and Co tetracarbonyls

The IR band intensities of Ni and Co tetracarbonyls were measured and the dipole moment derivatives of the compounds were calculated. The effective charges on C and O atoms were estimated using the procedure suggested in a previous paper.     

Theoretical interpretation of the vibrational spectrum of bicyclo[1.1.0]butane in terms of an ab initio anharmonic model

The anharmonic vibrational IR and Raman spectra of the bicyclo[1.1.0]butane molecule have been calculated in the range of up to 4000 cm^?1 using a numerical and analytical realization of the van Vleck second-order operator perturbation theory. Cubic and quartic force constants in normal coordinates, as well as cubic surfaces of the dipole moment and polarizability, have been found by numerical differentiation of the corresponding first and second derivatives calculated by the MP2/cc-pVTZ quantum-mechanical method. In order to increase the prediction accuracy of vibrational transitions, corresponding harmonic frequencies have been obtained by the CCSD(T)/cc-pVTZ high-precision quantum mechanical method. The anharmonic intensities of the IR and Raman spectra have been calculated using canonical transformations of the operators of the dipole moment and polarizability expanded into a Taylor series around the equilibrium configuration. The assignment of experimental vibrational bands in the IR and Raman spectra has been analyzed. It has been shown that the anharmonic calculation based on the above-described procedure of combining more exact harmonic frequencies with the anharmonic force field obtained with a more economical method makes possible the reliable interpretation of the majority of spectral bands, including Fermi and Darling-Dennison resonances.     

ZnO在辐射场中的光激发特性研究

采用密度泛函理论的BPV86方法, 在6-311G++(d, p)基组水平上优化了不同外电场(0～0.080 a.u.)下氧化锌分子的基态稳定构型, 在此基础上利用同样的方法计算了氧化锌分子的分子结构、偶极矩、总能量、能隙以及红外光谱和紫外-可见吸收光谱强度。结果表明, 在外电场的作用下, 分子结构变化明显, 与电场呈现强烈的依赖关系。随着正向外加电场的增加, ZnO分子键长一直在增大, 电偶极距也是一直增大, 分子总能量不断减小, 分子能隙不断减小, 红外光谱吸收峰出现红移现象。随着外电场的加强, 分子紫外可见吸收光谱振子强度先增大后减小再增大再减小反复变化, 其波峰则出现蓝移现象。