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1.
The infrared and Raman spectra of barium oxalate hemihydrate, BaC2O4 · 0.5H2O, were recorded and discussed on the basis of their structural peculiarities and in comparison with the spectra of the previously investigated calcium and strontium oxalates. 相似文献
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本文比较了可溶性与不可溶性聚苯胺的红外吸收光谱与 Raman 光谱,表明两种聚苯胺在结构上有明显差别。可溶性聚苯胺的主要红外特征峰频率向高频方向移动,吸收带变窄,肩峰清晰可辨。对应于醌基团振动的1595cm~(-1)谱线相对于苯基团振动的1499cm~(-1)谱线强度减弱,1300cm~(-1)谱峰消失。表明可溶性聚苯胺中醌结构单元的数量少,而且含有偶氮基团 N=N 伸缩振动的特征吸收峰1450cm~(-1)。比较两者的 Raman 光谱也给出了相同的结果。可溶性聚苯胺中相对于氧化单元中醌结构的特征峰1566cm~(-1)谱线比相对于还原单元中苯结构的特征峰1620cm~(-1)谱线强度弱得多,也表明可溶性聚苯胺比不可溶性聚苯胺含有较少的醌结构。根据聚苯胺导电机制的质子化模型,由红外与Raman 光谱中相应谱的相对强度的差别可以估计,可溶性聚苯胺具有氧化型与还原型交替结构,质子化程度较低,仅约15%,因此电导率显著下降。 相似文献
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Nancy Mancilla Maria C. D'Antonio Ana C. Gonzlez‐Bar Enrique J. Baran 《Journal of Raman spectroscopy : JRS》2009,40(12):2050-2052
The infrared and Raman spectra of anhydrous lead oxalate (PbC2O4) were recorded and discussed on the basis of its structural peculiarities. Some comparisons with other previously investigated metallic oxalates were made. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
6.
Their and Raman spectra of molybdenum trioxide—monohydrate are studied assuming an effective tetrahedral Mo-O coordination and
isolated water molecules, although the crystallographic coordination is six-fold with two long Mo-O distances. Based onCt symmetry, the group theoretical analysis has been carried out and a vibrational assignment is proposed. The nature of hydrogen
bonding and the librational modes of water molecules are discussed. The factor group splitting forv3, the asymmetric stretching mode of MoO4
= ion, is large indicating strong interchain coupling. 相似文献
7.
Felix Zrgiebel Jens Kunstmann Daijiro Nozaki Gianaurelio Cuniberti 《Journal of Raman spectroscopy : JRS》2012,43(9):1214-1220
The characterization of nanostructures with spectroscopic methods is a fundamental tool in nanoscience. For novel nanostructures, the interpretation of spectral features is a challenging task. To address this issue, we present the “Symmetry‐Filtered Molecular Dynamics (SFMD)” method to calculate Raman and infrared wavenumbers from molecular dynamics (MD) simulations, employing only the symmetry of the atomic structure. Explicit and expensive calculations of the electric polarizability or the dipole moment are not required. Therefore, our method can be easily used with any standard MD software. On the basis of the density functional tight‐binding method for the MD simulations, we apply our method to bulk silicon and small‐diameter hydrogen‐passivated silicon nanowires. For bulk silicon, we study the wavenumber shift of the Raman peak with temperature and obtain results that are in good agreement with experiments. We further show that thermal lattice expansion is a minor effect (22%) and that temperature‐driven anharmonic effects (78%) are the main contributions to that wavenumber shift. By analyzing the bond lengths of different silicon nanowires, we found that surface stress manifests as a 0.37% shortening of bonds only in the outermost silicon layer. We further analyzed the diameter‐dependent wavenumber shift of a Raman peak in silicon nanowires. We found that the main contribution to the wavenumber shift comes from the phonon confinement effect and surface stress leads to an additional shift of 9–22%. Our results indicate that our method is able to produce quantitative results that can be compared with experiments. We propose our method to be used for the understanding of Raman and infrared spectra of novel bulk and nanostructures. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
8.
The infrared and laser Raman spectra of 2, 3 dichloro aniline and 2, 6 dichloro aniline have been recorded. The vibrational
spectra have been analysed assumingC
s andC
2v
point groups for 2, 3 dichloro aniline and 2, 6 dichloro aniline respectively. Assignments for fundamental vibrations, combination
and overtone frequencies and internal modes of vibration of amino group have been proposed. 相似文献
9.
Gamil A. Guirgis Sarah Xiaohua Zhou James R. Durig 《Journal of Raman spectroscopy : JRS》2010,41(3):303-309
The Raman (3200‐30 cm−1) and/or infrared spectra (3500 to 400 cm−1) of gaseous, liquid and solid dimethylsilylisocyanate, (CH3)2 Si(H)NCO, have been recorded. The MP2(full) calculations, employing a variety of basis sets with and without diffusion functions, have been used to predict the structural parameters, conformational stability, vibrational fundamental wavenumbers, Raman activities, depolarization values and infrared intensities to support the vibrational assignment. The low wavenumber Raman spectrum of the gas with a significant number of Q‐branches for the SiNC(O) bend is consistent with an essentially linear SiNCO moiety. The ab initio calculations supported this conclusion as all possible orientations of the NCO moiety lead to nearly the same energy. This result is at variance with the conclusion from the electron diffraction study that the heavy atom skeleton was bent with an angle of 152(5)° with one stable cis conformer. It is believed that this reported angle difference from 180° is due to the shrinkage effect. The SiH distance of 1.486 Å has been obtained from the isolated SiH stretching wavenumber. From the adjustment of the ab initio MP2(full)/6‐311+G(d,p) predicted structural parameters, a proposed structure is reported, which is expected to give rotational constants within a few megahertz of the actual ones. These experimental and theoretical results are compared with the corresponding quantities of similar molecules. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
10.
The 3‐methoxy‐4‐hydroxybenzoic acid or vanillic acid (VA) is a naturally occurring molecule important in winemaking. The spectral fingerprints of VA observed in the infrared and Raman spectra are assigned to fundamental vibrational wavenumbers supported by quantum chemical computations. The surface‐enhanced Raman scattering (SERS) of the VA has been obtained in silver colloidal solutions making possible analytical applications for detection of VA at picomole concentrations. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Seng Khoon Teh Wei Zheng Khek Yu Ho Ming Teh Khay Guan Yeoh Zhiwei Huang 《Journal of Raman spectroscopy : JRS》2009,40(8):908-914
Raman spectroscopy is a molecular vibrational spectroscopic technique that is capable of optically probing the biomolecular changes associated with neoplastic transformation. The purpose of this study was to apply near‐infrared (NIR) Raman spectroscopy for differentiating dysplasia from normal gastric mucosa tissue. A total of 65 gastric mucosa tissues (44 normal and 21 dysplasia) were obtained from 35 patients who underwent endoscopy investigation or gastrectomy operation for this study. A rapid NIR Raman system was utilized for tissue Raman spectroscopic measurements at 785‐nm laser excitation. High‐quality Raman spectra in the range of 800–1800 cm−1 can be acquired from gastric mucosa tissue within 5 s. Raman spectra showed significant differences between normal and dysplastic tissue, particularly in the spectral ranges of 850–1150, 1200–1500 and 1600–1750 cm−1, which contained signals related to proteins, nucleic acids and lipids. The diagnostic decision algorithm based on the combination of Raman peak intensity ratios of I875/I1450 and I1208/I1655 and the logistic regression analysis yielded a diagnostic sensitivity of 90.5% and specificity of 90.9% for identification of gastric dysplasia tissue. This work demonstrates that NIR Raman spectroscopy in conjunction with intensity ratio algorithms has the potential for the noninvasive diagnosis and detection of precancer in the stomach at the molecular level. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Taejin Kim Rajeev S. Assary Larry A. Curtiss Christopher L. Marshall Peter C. Stair 《Journal of Raman spectroscopy : JRS》2011,42(12):2069-2076
In this work, the Raman spectra of furan, furfuryl alcohol (FA), furfural, hydroxymethylfurfural (HMF), and levulinic acid were obtained in the 500 to 4000 cm−1 spectral region at room temperature. Vibrational wavenumbers were calculated for these compounds with the B3LYP method using the 6‐31 + G(2df,p) basis set. The experimentally determined CC and C C wavenumbers for furan and furan derivatives were in good agreement with the calculated wavenumbers without scaling factor, while the calculated CO and C H wavenumbers at ∼1660 and 3000 cm−1, respectively, showed larger deviations from the measured ones. The Raman spectra for furan and furan derivatives showed intense CC bands, whereas the levulinic acid spectrum showed intense C H vibrations with broad doublet CO bands. We also found that an empirical method based on the chemical structure similarities is able to predict the HMF Raman spectrum from the combined furfural and FA spectra. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
14.
Claudia C. Wagner Selene Calvo María H. Torre Enrique J. Baran 《Journal of Raman spectroscopy : JRS》2007,38(4):373-376
The infrared and Raman spectra of 5‐chloro‐7‐iodo‐8‐hydroxyquinoline (clioquinol, CQ) and that of its Cu(II) complex of stoichiometry [Cu(CQ)2] were recorded and briefly discussed. Some comparisons were made with related complexes. The interest of the investigated systems in relation to Alzheimer's disease is briefly commented. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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Polaprezinc, the Zn(II) complex of the dipeptide carnosine (β‐alanyl histidine) presents an interesting biological and pharmacological activity, specially as an anti‐ulcer agent. The infrared and Raman spectra of this compound were recorded and briefly discussed. Some comparisons were made with related complexes and with free carnosine. The results confirm the coordination environment of the Zn(II) cation, constituted by the terminal amino N‐atom, the deprotonated amide N‐atom and one carboxylate oxygen of one dipeptide molecule and the N‐atom of the imidazole moiety of a second carnosine molecule. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
16.
The laser Raman spectrum of tere-phthalaldehyde powder has been recorded on a Jobin Yvonhg 2S spectrophotometer with a~100 mW Argon-Ion laser. The infrared spectrum of the solid substance has been recorded on a Perkin-Elmer
621 spectrophotometer in the region 300–4000 cm-1 using KBr and nujol mull techniques. The observed frequencies have been assigned in terms of the fundamentals, overtones
and combinations assumingD
2h point-group symmetry. 相似文献
17.
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
18.
Raman and infrared intensity analysis of CHCl3 is attempted to determine the bond polarisability derivatives and bond dipole moments and their derivatives respectively,
on lines expained in our earlier papers. 相似文献
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Volodymyr Dzhagan Nikolai Mel'nik Olexandra Rayevska Galyna Grozdyuk Viktor Strelchuk Olga Plyashechnik Stepan Kuchmii Mykhailo Valakh 《固体物理学:研究快报》2011,5(7):250-252
Resonant Raman scattering spectra of ultrasmall (<2 nm) magic‐size nanocrystals (NCs) are reported. The spectra of CdS and CdSx Se1‐x NCs, resonantly excited with 325 nm and 442 nm laser lines, correspondingly, reveal broad features in the range of bulk optical phonons. The relatively large width, ~50 cm‐1, and downward shift, ~20 cm‐1, of the Raman bands with respect to the longitudinal optical phonon in bulk crystals and large NCs are discussed based on the breaking of the translational symmetry and bond distortion in these ultrasmall NCs. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
20.
The powder Fourier‐transform (FT) infrared (IR) and Raman spectra of the recently characterized NH4Ag3(PO3F)2 were recorded and are discussed with a site‐symmetry analysis based on its known structural data. Some comparisons are made with the solution spectra of the PO3F2− anion and with those of crystalline Ag2PO3F. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献