低温相HI分子晶体振动光谱计算

低温相ＨＩ分子晶体振动光谱计算毛延哲曾维扬（兰州大学物理系兰州７３００００）ＣａｌｃｕｌａｔｉｏｎｏｆｔｈｅＶｉｂｒａｔｉｏｎａｌＳｐｅｃｔｒｏｓｃｏｐｙｏｆＣｒｙｓｔａｌｉｎｅＨｙｄｒｏｇｅｎＩｏｄｉｄｅＭａｏＹａｎｚｈｅ（Ｄｅｐｔ．ｏｆｆｕｎｄ...     

直角坐标系中的分子和分子晶体振动光谱分析

本文介绍在直角坐标系中用简单的弹性力常数模型分析振动光谱的方法,这种方法在处理孤立分子时与传统的 GF 矩阵法等效,而对于分子晶体振动的动力学计算具有一定的优越性。它利用统一的数学公式来描述晶体中分子内外的相互作用从而同时获得分子外部振动频率和内部模式在晶体场中分裂的信息。     

低温相H_2S晶体振动光谱计算

本文介绍了计算分子晶体基频振动的力常数模型并应用于Ｈ２Ｓ晶体低温相的拉曼，红外光谱分析。使用１１个可调参数（包括３个分子内部力常数和８个分子间作用力参数）计算得到６９个光学模式的振动频率及其对应的本征矢量。计算结果与实验值相符甚好。对已观测到的谱线作了全面指认。并给出了未观测到谱线的位置。计算表明，晶体中氢键为最重要的分子间相互作用。它使Ｈ２Ｓ分子Ｓ—Ｈ键力在晶体中减弱７％。     

α方石英振动光谱的计算

在价力场模型和已公布的α方石英喇曼光谱和红外光谱不完全的观测数据基础上，计算了α方石英振动光谱横模的全部基频和简正模式。基频的计算值和观测值符合较好。预言了至今尚未观测到的对称类Ａ２、Ｂ１各两个基频和Ｂ２的５个基频的位置。给出了α方石英的一组１０个力常数     

基态SiH~+分子离子光谱常数与振动能级研究

首先根据群论及原子分子反应静力学的相关知识,推导了SiH+分子离子基态X1Σ+的电子态和合理的离解极限。然后采用Gaussian 09程序包中优选出的QCISD(T)方法结合cc-pVQZ基组,对SiH+分子离子基态结构进行了优化计算。运用相同方法对SiH+分子离子基态进行了单点势能扫描,分别采用9参数Murrell-Sorbie函数及Murrell-Sorbie+c6函数进行了非线性最小二乘拟合,首次得到了SiH+分子离子基态的势能函数和相应的光谱常数ωe,ωexe,Be,αe。计算结果表明,利用9参数Murrell-Sorbie函数计算所得的光谱常数与实验光谱数据吻合得更好,相对误差分别为0.13%,3.07%,0.38%,5.25%以及0.52%,这些数据均说明9参数Murrell-Sorbie势能函数能更好地描述SiH+分子离子基态的性质,拟合所得势能曲线准确地再现了其离解能和平衡结构特征。通过求解双原子分子核运动的径向薛定谔方程,首次报道了SiH+分子离子基态在J=0时的振动能级、转动惯量和六个离心畸变常数。为实验上找到对应的跃迁提供了理论依据。     

用电离光谱技术测量钾分子激发态的振动常数

用染料激光激发钾蒸气，观察到了与钾分子电子态5^3Hu振动能级相关的电离谱，根据电离谱峰对应的激光波长值计算出了钾分子5^3Hu态的振动结构常数，在实验误差范围内与Magnier和Millie的理论计算结果一致。     

乙基苯的振动光谱和量化计算

用单色双光子共振电离方法研究了乙基苯的第一激发态的振动光谱. 从基态跃迁到第一激发态的带源位置出现在37586 cm^-1处.获得的第一激发态振动光谱超过了2000 cm^-1,并观察到了几个乙基取代基的扭转振动和与苯相似的正则振动. 同时,用含时密度泛函理论和单组态相互作用(CIS)方法计算了第一激发态的跃迁能量,用Hartree-Fock和CIS方法优化了基态和第一激发态分子结构,预测了振动频率. 基态和激发态结构的优化结果均显示为顺式结构,即乙基取代基的对称面垂直了苯基平面.     

Vibrational Behaviour of the CrO3- 4 Anion in Different Crystalline Environments

The powder-infrared spectra of different crystalline compounds containing the tetrahedral Cro^3- ₄, anion have been recorded and analyzed with the aid of the site symmetry rules. In some cases Raman data are also reported. The effect of the different crystalline environments is discussed in detail and comparisons with isostructural phases are also made. A definitive assignment for the internal vibrations of the CrO^3- ₄, ion is proposed and a new set of force constants has been calculated fron a modified valence force field.     

Vibrational Spectra and Radiation-Stimulated Change in the Structure of Crystalline Silica

A spectroscopic investigation of a radiation-stimulated change in the structure of a phase transition in a crystalline silica (alpha quartz) exposed to a set of fluences of fast neutrons has been carried out using optical methods (IR reflection spectroscopy, Raman scattering) and x-ray methods. The laws governing the change in the spectral characteristics of some bands as a result of structural transformation of the crystal on exposure to radiation and the change in the parameters of the stretching and deformation vibrations of bridge bonds have been established. It is assumed that irradiation of a crystal leads to two processes of destruction of the Si—O—Si bonds and their deformation, causing a change in the initial structure. The x-ray spectroscopy data for individual parameters were compared to the Raman spectrum for a heated quartz. A conclusion has been drawn concerning the correlation between corresponding dependences and the formation of a state similar to the high-temperature modification of quartz at a certain stage of irradiation with fast neutrons.     

Raman and Infrared Spectra of Crystals with the Cadmium Iodide Structure

Abstract

Raman and far infrared spectra (in the frequency range 20–360 cm^?1) have been recorded for polycrystalline samples of six crystals having the cadmium iodide layered structure. The four fundamental zone-center vibrational frequencies are assigned for CoBr₂, FeBr₂, MgBr₂, MnBr₂, CdI₂ and MgI₂. Values of the principal interlayer force constants are deduced from a simple linear chain dynamical model, and comparisons are made with recent results from spectroscopic studies of crystals with the related cadmium chloride structure.     

Vibrational Properties of Pertechnetyl Fluoride

Abstract

Pertechnetyl fluoride, TcO₃F, had been prepared some years ago¹, but its vibrational spectrum was only recently recorded and interpreted². The spectroscopic study reveals that, as expected, TcO₃F posseses C_3v symmetry, and the values found for the fundamental vibrations are in good agreement with those previously estimated by Müller et al.³ in a paper concerning with the vibrational behaviour of MO₃X^n? species, and some systematic relations among them (cf. also⁴).     

Implementing the Theory of Sum Frequency Generation Vibrational Spectroscopy: A Tutorial Review

Abstract

The interfacial regions between bulk media, although often comprising only a fraction of the material present, are frequently the site of reactions and phenomena that dominate the macroscopic properties of the entire system. Spectroscopic investigations of such interfaces are often hampered by the lack of surface specificity of most available techniques. Sum frequency generation vibrational spectroscopy (SFS) is a non‐linear optical technique which provides vibrational spectra of molecules solely at interfaces. The spectra may be analysed to provide the polar orientation, molecular conformation, and average tilt angle of the adsorbate to the surface normal. This article is aimed at newcomers to the field of SFS, and via a tutorial approach will present and develop the general sum frequency equations and then demonstrate how the fundamental theory elucidates the important experimental properties of SFS.     

Calculation of the Interatomic Force Constants of Pyrazole

In the frame of a more complete study on the tautomery of the pyrazolines-5-ones, the authors determined the normal vibration modes of pyrazole. They calculate the interatomic force constants by means of a “simplex” optimisation procedure (1).     

Calculation of the Normal Vibrations of Benzene in the First Singlet Electron-Excited State 1 B 2u

Using the CIS/6-311+G^** method, the normal vibrations of the benzene molecule in the first singlet electron-excited state ¹ B _2u have been calculated. The algorithm of calculation of the force field in dependent coordinates by the method of generalized inversion is described. A method of autoscaling in dependent natural coordinates is suggested. For six groups of natural coordinates scaling factors have been obtained, the use of which has led to agreement between the calculated and experimental frequencies of the vibrations of benzene. The frequencies of the B _1u -symmetry-type vibrations, for which there is no experimental assignment, have been calculated. The problem of selection of the force field in dependent coordinates is discussed.     

Ab initio Calculation of Normal Vibrations of Chlorobenzene in the First Singlet Electron-Excitebd State 1 B 2

An analysis of experimental assignments of the frequencies of normal vibrations of chlorobenzene in the first singlet electron-excited state ¹ B ₂ has been performed with the use of two quantum-mechanical prediction methods — the method of frequency shifts and the method of transfer of scaling factors. Based on the data of this analysis, a new assignment of a number of vibration frequencies has been made. Normal vibrations of the chlorobenzene molecule in the excited state have been calculated by the CIS method with a 6-311 + G ^** basic set. An algorithm of autoscaling in dependent natural coordinates has been proposed. The force field of chlorobenzene has been scaled in dependent natural coordinates. It is shown that the scaling factors of benzene in the electron state ¹ B _2u can be used for calculating the frequencies of normal vibrations of chlorobenzene in the first singlet excited state ¹ B ₂.     

Vibrational Spectra of the Closed Form of a Molecule of Indoline Spiroanthraceneoxazine

In an approximation of the generalized valence force field, the frequencies and forms of the normal vibrations of the free molecule of spiroanthraceneoxazine (SAO) are calculated. The vibrational spectra of SAO are measured: the IR absorption spectra in an NaCl disk and the Raman spectra in a KBr disk. The calculated and experimental data were correlated with the aid of a method of refined initial data. The results obtained agree with the calculated and experimental spectra of model and related compounds. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 576–571, September–October, 2005.