共查询到20条相似文献,搜索用时 15 毫秒
1.
J. S. Singh 《Pramana》2008,70(3):479-486
Laser Raman (200–4000 cm−1) and IR (200–4000 cm−1) spectra of 5-aminouracil were recorded in the region 200–4000 cm−1. Assuming a planar geometry and Cs point group symmetry, it has been possible to assign all the 36 (25a′ + 11a″) normal modes of vibration for the first time. The two NH bonds of the NH2 group appear to be equivalent as the NH2 stretching frequencies satisfy the empirical relation proposed for the two equivalent NH bonds of the NH2 group. The two NH2 stretching frequencies are distinctly separated from the CH/NH ring stretching frequencies. A strong and sharp IR band at
3360 cm−1 could be identified as the anti-symmetric NH2 mode whereas the band at 3290 cm−1 with smaller density could be identified as the symmetric NH2 stretching mode. All other bands have also been assigned different fundamentals/overtones/combinations.
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2.
Ikhlas D. Darkhalil Joshua J. Klaassen Nick Nagels Wouter A. Herrebout Benjamin J. van der Veken Ranil M. Gurusinghe Michael J. Tubergen James R. Durig 《Journal of Raman spectroscopy : JRS》2014,45(5):392-406
Fourier transform microwave spectrum of cyclopentylamine, c–C5H9NH2 has been recorded, and seven transitions have been assigned for the most abundant conformer, and the rotational constants have been determined: A = 4909.46(5), B = 3599.01(4), and C = 2932.94(4). From the determined microwave rotational constants and ab initio MP2(full)/6‐311 + G(d,p) predicted structural values, adjusted r0 parameters are reported with distances (Å): rCα–Cβ = 1.529(3), rCβ–Cγ = 1.544(3), rCγ–Cγ = 1.550(3), rCα–N = 1.470(3), and angles (°) ∠CCN = 108.7(5), ∠CβCαCβ = 101.4(5), and τCβCαCβ′Cγ′ = 42.0(5). The infrared spectra (4000–220 cm−1) of the gas have been recorded. Additionally, the variable temperature (−60 to −100 °C) Raman spectra of the sample dissolved in liquefied xenon was recorded from (3800–50 cm−1). The four possible conformers have been identified, and their relative stabilities obtained with enthalpy difference relative to t‐Ax of 211 ± 21 cm−1 for t‐Eq ≥ 227 ± 22 cm−1 for g‐Eq ≥ 255 ± 25 cm−1 for g‐Ax. The percentage of the four conformers is estimated to be 53% for the t‐Ax, 11 ± 1% for t‐Eq, 20 ± 2% for g‐Ax and 16 ± 2% for g‐Eq at ambient temperature. The conformational stabilities have been predicted from ab initio calculations by utilizing several different basis sets up to aug‐cc‐pVTZ from both MP2(full) and density functional theory calculations by the B3LYP method. Vibrational assignments have been provided for the observed bands for all four conformers, which are predicted by MP2(full)/6‐31G(d) ab initio calculations to predict harmonic force constants, wavenumbers, infrared intensities, Raman activities, and depolarization ratios for all of the conformers. The results are discussed and compared to the corresponding properties of some related molecules. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
3.
The Raman spectrum of polycrystalline α-naphthylamine was recorded in the region 100–4000 cm−1. Polarisation measurements were made in CS2 and CHCl3 solutions. The infrared spectrum was recorded in nujol mull in the region 200–4000 cm−1. The resolution was better than 2 cm−1 and the accuracy of the measurements was within ± 2 cm−1 for all the spectra. Vibrational assignments have been proposed for the observed frequencies. Out of the 54 normal modes
of vibrations, 51 modes could be observed experimentally. 相似文献
4.
James R. Durig Ikhlas D. Darkhalil Joshua J. Klaassen Wouter A. Herrebout Johan J. J. Dom Benjamin J. van der Veken 《Journal of Raman spectroscopy : JRS》2012,43(9):1329-1336
The Raman and infrared spectra (4000 to 50 cm–1) of the gas, liquid or solution, and solid have been recorded of n‐propylamine, CH3CH2CH2NH2. Variable temperature (−60 to −100 °C) studies of the Raman (1175 to 625 cm–1) and far infrared (600 to 10 cm–1) spectra dissolved in liquid xenon were carried out. From these data, the five possible conformers were identified and their relative stabilities obtained with enthalpy difference relative to trans–trans (Tt) for trans–gauche (Tg) of 79 ± 9 cm–1 (0.9 ± 0.1 kJ/mol); for Gg of 91 ± 26 cm–1 (1.08 ± 0.3 kJ/mol); for Gg′ of 135 ± 21 cm–1 (1.61 ± 0.2 kJ/mol); for Gt of 143 ± 11 cm–1 (1.71 ± 0.1 kJ/mol). The percentage of the five conformers is estimated to be 18% for the Tt, 24 ± 1% for Tg, 23 ± 3% for Gg, 18 ± 1% for Gg′ and 18 ± 1% for Gt at ambient temperature. The conformational stabilities have been predicted from ab initio calculations utilizing several different basis sets up to aug‐cc‐pVTZ from both second‐order Møller–Plesset (MP2, full) and density functional theory calculations by the Becke, three‐parameter, Lee–Yang–Parr method. Vibrational assignments were provided for the observed bands for all five conformers, which are supported by MP2(full)/6‐31G(d) ab initio calculations to predict harmonic force constants, wavenumbers, infrared intensities, Raman activities and depolarization ratios for both conformers. Estimated r0 structural parameters were obtained from adjusted MP2(full)/6‐311+G(d,p) calculations. The results are discussed and compared with the corresponding properties of some related molecules. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
5.
Gamil A. Guirgis Ikhlas D. Darkhalil Joshua J. Klaassen Arindam Ganguly Justin K. Wyatt James R. Durig 《Journal of Raman spectroscopy : JRS》2012,43(1):116-126
The Raman and infrared spectra (3500–50 cm−1) of the gas, liquid or solution, and solid were recorded of 2,2,3,3,3‐pentafluoropropylamine (CF3CF2CH2NH2) and the ND2 isotopomer. Variable temperature (−55 to − 100 °C) studies of the infrared spectra (3600–400 cm−1) of samples dissolved in liquid xenon have been carried out. From these data, two of the five possible conformers have been identified and their relative stabilities obtained. The enthalpy difference was determined between the more stable Tt conformer and the less stable Tg form to be 280 ± 14 cm−1 (3.35 ± 0.17 kJ/mol). The first indicator is the NCCC dihedral angle (G = gauche or T = trans), and the second one (g = gauche or t = trans) is the relative position of the lone pair of electrons on nitrogen with respect to the β‐carbon. The percentage of the Tg conformer at ambient temperature is estimated to be 34 ± 2%. The conformational stabilities have been predicted from ab initio calculations utilizing several different basis sets up to aug‐cc‐pVTZ for both MP2(full) and density functional theory calculations by the B3LYP method. Vibrational assignments have been provided for most of the observed bands for both isotopomers, supported by MP2(full)/6‐31G(d) ab initio calculations to predict the harmonic force fields, wavenumbers, infrared intensities, Raman activities, and depolarization ratios for both conformers. Estimated r0 structural parameters were obtained from adjusted MP2(full)/6‐311 + G(d,p) calculations. The results are discussed and compared with the corresponding properties of some related molecules. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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近几年, 国内有关塑化剂的食品安全事件频发, 迫切需求加强对于食品中塑化剂的检测研究工作。邻苯二甲酸二辛酯是塑化剂的一种。理论计算和实验测量了邻苯二甲酸二辛酯的拉曼光谱。利用密度泛函理论DFT(B3LYP)的三参数混合方法对其进行了空间结构优化;然后分别用(Hartree-Fock)HF/3-21G和DFT/3-21G两种算法计算了它的拉曼光谱和红外光谱, 给出了光谱强度图。实验测量了分析纯级邻苯二甲酸二辛酯的拉曼光谱, 并和理论计算结果进行了对比, 显示了很好的一致性,与此同时由于计算方法的不同, 从图中可以看出Gaussian计算的HF和DFT算法无论是峰的位置还是相对强度等都均存在差别。还给出了常用塑化剂邻苯二甲酸二辛酯的各个键长、键角等空间结构参数, 并对邻苯二甲酸二辛酯分子在400~3 500 cm-1区间的振动谱做了指认。报道了常用塑化剂邻苯二甲酸二辛酯的拉曼光谱研究工作。这些工作将有助于拉曼光谱技术在食品检测领域的研究和应用。 相似文献
8.
近几年,国内有关塑化剂的食品安全事件频发,迫切需求加强对于食品中塑化剂的检测研究工作。邻苯二甲酸二辛酯是塑化剂的一种。理论计算和实验测量了邻苯二甲酸二辛酯的拉曼光谱。利用密度泛函理论DFT(B3LYP)的三参数混合方法对其进行了空间结构优化;然后分别用(Hartree-Fock)HF/3-21G和DFT/3-21G两种算法计算了它的拉曼光谱和红外光谱,给出了光谱强度图。实验测量了分析纯级邻苯二甲酸二辛酯的拉曼光谱,并和理论计算结果进行了对比,显示了很好的一致性,与此同时由于计算方法的不同,从图中可以看出Gaussian计算的HF和DFT算法无论是峰的位置还是相对强度等都均存在差别。还给出了常用塑化剂邻苯二甲酸二辛酯的各个键长、键角等空间结构参数,并对邻苯二甲酸二辛酯分子在400~3 500 cm-1区间的振动谱做了指认。报道了常用塑化剂邻苯二甲酸二辛酯的拉曼光谱研究工作。这些工作将有助于拉曼光谱技术在食品检测领域的研究和应用。 相似文献
9.
D. P. Chiang C. H. Peng J. K. Mei I. M. Jiang S. C. Lin Y. C. Chen H. T. Liu Y. F. Chen W. S. Tse 《Journal of Raman spectroscopy : JRS》2008,39(3):344-348
Raman studies of crystalline iron perchlorate hexahydrate (Fe(ClO4)2·6H2O) in the region of lattice and anion internal modes were carried out in the temperature range 80–385 K. The temperature‐dependent Raman results are consistent with those from previous works, showing that two phase transitions occur around 336 and 245 K. The transition at 336 K may be considered as an order–disorder transformation, while the one at 245 K is associated with the configurational disorder of the tetrahedron of the perchlorate ions. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
10.
Gadolinium manganese sulfide solid solutions are investigated by infrared and Raman spectroscopy. Longitudinal optical–transverse optical splitting of the manganese–sulfur bond vibration is observed in the vibrational spectra. The Raman spectra contain modes that are prohibited in the crystal structure of the alpha phase of manganese sulfide, which are associated with activation of the phonons from both the Brillouin zone center and its X and L points. The concentration dependence of transverse optical and longitudinal optical modes’ frequencies is calculated within the frame of the modified random-element-isodisplacement model, being in good agreement with the experimental results. Both theory and experiment show that the solid solution under study exhibits a “one-mode” behavior. 相似文献
11.
采用太赫兹时域光谱和拉曼光谱法对L-苏氨酸多晶粉末进行测试研究,获得了样品在0.2—2.8 THz(6.7—93.2 cm-1)波段的特征吸收和10—4000 cm-1波段的拉曼散射谱;分别在6.7—93.2 cm-1和400—4000 cm-1两个波段进行了吸收光谱与拉曼散射光谱的对比,根据晶胞分子所属的空间群,对隶属于分子的极性和非极性振动模式(A, B1,
关键词:
太赫兹光谱
拉曼散射
氨基酸 相似文献
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利用傅里叶红外光谱和共聚焦显微拉曼光谱技术,比较分析了大蒜主要功能活性成分前体蒜氨酸和甲基蒜氨酸粉末纯品的红外和拉曼谱。在3 200~2 800 cm-1和1 700~200 cm-1波段检测到显著的红外和拉曼吸收峰,其中蒜氨酸在3 080,1 617,1 582,1 496,1 418,1 342,1 301,919 cm-1处有8个较强的红外吸收峰,以及在3 088,1 636,1 404,1 290,1 051,790,745,693,588 cm-1处有9个较强的拉曼振动峰,可作为蒜氨酸的特征峰;甲基蒜氨酸在1 644,1 481,1 395,1 370,1 233,1 068,1 004,892 cm-1处有8个较强的红外吸收峰,以及在1 644,1 310,1 073,1 011,998,893,846,702,676 cm-1处有9个较强的拉曼振动峰,可作为甲基蒜氨酸的特征峰。蒜氨酸和同系物甲基蒜氨酸的红外及拉曼光谱具有明显差异,红外及拉曼光谱技术为蒜氨酸及其同系物的快速、 简便的分析提供了方法。 相似文献
14.
我们采用传统的助熔剂合成方法制备单斜RbInS2、CsInS2晶体并对它们的红外光谱和拉曼光谱进行研究。与RbInS2相比,CsInS2的红外吸收峰和拉曼吸收峰向长波方向移动。红外光谱和拉曼光谱均表明单斜RbInS2、CsInS2具有很好的红外透过性能。 相似文献
15.
I. V. Bodnar 《Journal of Applied Spectroscopy》1998,65(3):466-468
Raman spectra in (┴, ┴) and (║, ║) polarizations are investigated on crystals of CuGaS2, AgGaS2 compounds and CuxAgl−xGaS2 solid solutions. The frequencies of longitudinal and transverse optical phonons are determined, their concentration dependences
are constructed, and the behavior of the vibrational modes in CuxAgl−xGaS2 solid solutions is established.
Belarusian State University of Information Science and Radioelectronics, 6P, Brovka St., 220069, Minsk, Belarus. Translated
from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 3, pp. 447–449, May–June. 1998. 相似文献
16.
The Fourier‐transform infrared (FT‐IR) (4000–50 cm−1) and Raman spectra (3500–100 cm−1) of 1,4,5‐triazanaphthalene in polycrystalline state were measured. Comparison between the spectra by two techniques, a series of density functional theory (DFT) calculations and the spectral behaviour upon deuteration were used for the assignment of the vibrational spectra of the title compound. The calculated vibrational wavenumbers by the B3LYP density functionals are generally consistent with the observed spectra. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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利用激光显微拉曼光谱仪采集了三种苯并咪唑类农药(多菌灵、噻菌灵和苯菌灵)的拉曼光谱。应用密度泛函理论(DFT)中的B3LYP杂化泛函和6-31G(d, p)基组对三种苯并咪唑类农药分子进行结构优化和拉曼光谱振动频率计算。结果表明,理论计算得到的振动频率值与实验测得值吻合较好。对三种苯并咪唑类农药分子在200~3 500 cm-1范围内的振动模式进行归属,找到了苯并咪唑类分子的3个特征峰,分别位于1 015, 1 265 cm-1和1 595 cm-1附近;对比分析三种农药拉曼光谱的差异性,找到三种农药分子各自不同的特征峰。研究结果可为苯并咪唑类农药的拉曼光谱分析提供理论依据,将促进食品和农产品中苯并咪唑类农药残留的快速检测研究。 相似文献
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G. A. Crowder 《光谱学快报》2013,46(7):713-717
Abstract The liquid-state Raman spectrum was obtained for chloromethyl thiocyanate. The previously unobserved C-S-C bending band was observed at 188 cm?1. The Raman spectrum supports the conclusion that only the CS conformer is present. 相似文献
20.
研究伪麻黄碱的拉曼光谱和吸附在纳米银基底上的表面增强拉曼光谱(SERS),利用密度泛函理论B3LYP/6-311G++(d, p)方法对伪麻黄碱分子进行了计算,得到了分子构型信息和理论拉曼光谱,用Gaussview软件对分子振动模式进行了全面的归属,在伪麻黄碱的表面增强拉曼光谱中,采用了自组装方法获得了团簇银纳米表面增强基底,实现了很好的增强效应.实验结果表明:伪麻黄碱的拉曼光谱计算结果和实验结果基本一致,理论计算为伪麻黄碱分子振动峰位的归属提供了重要的依据,伪麻黄碱分子与银纳米表面化学吸附,苯环垂直于纳米基底表面,研究结果为伪麻黄碱的拉曼光谱检验分析提供了理论依据,也为苯丙胺类毒品的光谱分析研究提供了参考. 相似文献