共查询到20条相似文献,搜索用时 9 毫秒
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A. J. Barclay A. Mohandesi K. H. Michaelian A. R. W. McKellar 《Molecular physics》2018,116(23-24):3468-3474
ABSTRACTThe fundamental band for the OC-C2H2 dimer and two combination bands involving the intermolecular bending modes ν9 and ν8 in the carbon monoxide CO stretch region are re-examined. Spectra are obtained using a pulsed supersonic slit jet expansion probed with a mode-hop free tuneable infrared quantum cascade laser. Analogous bands for OC-C2D2 and the fundamental for OC–DCCH as an impurity are also observed and analysed. A much weaker band in the same spectral region is assigned to a new mixed trimer, CO-(C2H2)2. The trimer band is composed uniquely of a-type transitions, establishing that the CO monomer is nearly aligned with the a-inertial axis. The observed rotational constants agree well with ab initio calculations and a small inertial defect value indicates that the trimer is planar. The structure is a compromise between the T-shaped structure of free acetylene dimer and the linear geometry of free OC-C2H2. A similar band for the fully deuterated isotopologue CO-(C2D2)2 confirms our assignment. 相似文献
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《Journal of Molecular Spectroscopy》1986,118(1):132-144
The infrared spectrum of the b3Σ− → a3Π Ballik-Ramsay system has been observed for both 13C2 and 12C13C isotopic species using high-resolution Fourier transform spectroscopy. Twelve bands: 0 → 0, 1 → 0, 1 → 1, 2 → 0, 2 → 1, 3 → 1, 3 → 2, 4 → 2, 4 → 3, 5 → 2, 5 → 3, 6 → 3 of 13C2 and seven bands: 0 → 0, 1 → 0, 1 → 1, 2 → 0, 2 → 1, 3 → 1, 3 → 2 of 12C13C were identified in the spectral range 3500–12 000 cm−1. Perturbations in the b3Σ− (v = 0, 1, 2, 3) levels were reduced and accurate perturbation parameters derived from the analysis. A comparison with ab initio calculated spin-orbit coupling constants is presented. 相似文献
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D.A. Steiner T.R. Todd C.M. Clayton T.K. McCubbin S.R. Polo 《Journal of Molecular Spectroscopy》1977,64(3):438-451
The emission spectrum of 13C16O2 near 4.5 μm, the ν3 transition region, was measured in high resolution. The sequence 00v3 → 00(v3 ? 1) was measured to v3 = 9, 011v3 → 011(v3 ? 1) to v3 = 6, and 022v3 → 002(v3 ? 1) to v3 = 3. Several bands involving Fermi resonant Σ state were also observed. The data were analyzed and spectroscopic constants were determined for all bands identified. 相似文献
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Claudio Degli Esposti Luca Dore Luciano Fusina Filippo Tamassia 《Molecular physics》2013,111(7):896-902
The pure rotational spectrum of 13C2HD was recorded in the range 100–700 GHz. Lines belonging to the ground vibrational state were observed from J″ = 1 to J″ = 11. Several absorption lines were also detected in the bending states v4 = 1 (Π), v5 = 1 (Π), v4 = 2 (Σ+ and Δ), v5 = 2 (Σ+ and Δ), v4 = v5 = 1 (Σ?, Σ+ and Δ), v4 = 3 (Π and Φ) and v5 = 3 (Π and Φ). The transition frequencies measured in this work were fitted together with all the infrared lines available in the literature. The global fit allowed a very accurate determination of the vibrational, rotational and ?-type interaction parameters for the bending states of this molecule. 相似文献
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GIAO calculations of the 1H NMR chemical shifts for ethanol at the SCF and DFT levels of theory are presented. The importance of molecular geometry and basis set is discussed. Vibrational correction to the hydroxyl proton chemical shift is also considered in calculations for the monomer of ethanol. The final theoretical results for the monomer obtained at the optimized DFT/B3LYP/6-311G(d,p) geometry with the 6-311G++ (d,p) basis set for NMR are in very good agreement with gas phase experimental data. For the liquid phase ethanol the hydrogen bonding effects are taken into account by performing calculations on various clusters of ethanol. It is shown that inaccuracy due to molecular geometry and basis set in the monomer of ethanol is magnified significantly in calculations for its clusters. In this context the structure of liquid ethanol as predicted recently by quantum cluster equilibrium (QCE) theory is discussed. 相似文献
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《Journal of Physics and Chemistry of Solids》1987,48(9):813-818
Three crystalline modifications of 2-aminobenzoic acid (anthranilic acid) have been studied by 13C CP/MAS and 1H CRAMPS NMR. The peaks are assigned and discussed in relation to (a) the neutral or zwitterionic nature of the molecules, (b) the crystal structures, known for two of the polymorphs, (c) residual (N,C) dipolar splittings, (d) hydrogen bonding and (e) dynamic exchange. The value of applying both types of spectroscopy to such studies is stressed. 相似文献
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V.E. Zuev V.P. Lopasov L.N. Sinitsa A.M. Solodov 《Journal of Molecular Spectroscopy》1982,94(1):208-210
The acetylene absorption spectrum in the Nd-laser range 9240–9520 cm?1 has been recorded earlier (1), using a highly sensitive intracavity laser spectrometer. Two weak absorption perpendicular bands 2100011 ← 0000000 (ν0 = 9366.6 cm?1) and 1200°31 ← 0000°0° (ν0 = 9407.7 cm?1) were studied and spectroscopic constants were obtained. However, the structure of the Q branches of these bands with J < 7 was unresolved because the resolution of the spectrometer was not very high. 相似文献
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A few bands of the C1IIg -A1IIu system of 12C13C molecule have been photographed and five of them have been rotationally analyzed. Molecular constants for v = 0, 1 and 2 in the C1 IIg and in A1IIu states have been obtained using a nonlinear least-squares procedure in which all analyzed bands were fitted simultaneosly. 相似文献
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The complete structural analysis of 1-[(4-methoxyphenyl)-(3,4,5-trimethoxyphe- nyl)methyl]naphtalene 5a and 1-[(2,5-dimethoxyphenyl)-(3,4,5-trimethoxyphenyl) methyljnaphtalene 5b, prepared by alkylation of 1-[chloro-(3,4,5-trimethoxyphenyl) methyl]naphtalene without by-products such as benzofluorene 2, may be accurately determined by 1H, 13C NMR and 2D NMR analysis. 相似文献
13.
Boyi Zhou 《Molecular physics》2017,115(19):2442-2450
Quantum close-coupling computations of the rotational quenching of H2 and its isotopologues due to He impact are performed using a highly accurate potential energy surface. State-to-state cross sections are obtained in a wide range of collision energies between 10?5 cm?1 and 104 cm?1, and the theoretical rate coefficients are reported for temperatures ranging from 10?4 K to 3000 K. Compared with previous studies, the well depth of the potential adopted in this study is larger, leading to stronger resonance effects in the cross sections of He-HD. The accurate potential was employed to investigate the isotope effects of H2 in detail. The cross-section resonances shift towards lower collision energies and become stronger with increasing reduced mass. The calculated cross sections and rate coefficients of H2 and its isotopic variants in collisions with He are provided to study the energy transfer in these systems. 相似文献
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报道了一种热转印色带用黄染料的1H、13C NMR , 应用1H NMR、13C NMR、定量碳谱、DEPT、1H-1H COSY、HMQC、HMBC等确定了其在氘代氯仿中的分子结构, 并对全部谱峰进行了归属, 探索了黄染料在氘代氯仿中的结构对13C、1H NMR谱图化学位移及谱峰裂分的影响. 相似文献
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雪胆素C是一个雪胆素甲在碱性条件下,乙酰基转移产生的同分异构体. 文中报道了应用13C NMR-DEPT、1H-1H COSY, NOESY, 13C-1H COSY等多种NMR技术,对雪胆素C的NMR碳氢化学位移完全指定. 相似文献
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S. Ertl F. Seibel L. Eichinger F. H. Frimmel A. Kettrup 《Isotopes in environmental and health studies》2013,49(3):245-253
Abstract Isotope ratios of technically and biologically produced halogenated hydrocarbons (HHC) are presented. Compared to the parent compounds, there is a significant enrichment of deuterium depending on the manner of production, whereas the carbon isotope ratio was only slightly influenced. Furthermore, there is nearly no alteration of the carbon isotope ratio due to biological degradation, so that the carbon fingerprint of the parent compounds is maintained in the metabolites. In contrast to this, the hydrogen isotope ratio of the metabolites reflects the ratio of the surrounding water. These results show that the isotopic fingerprint is a useful tool to distinguish between age, different charges of chemical dumping, and in addition to that, whether there is a contamination with technical products or residual metabolites. 相似文献
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Soubias O Réat V Saurel O Milon A 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2002,158(1-2):143-148
High resolution 2D NMR MAS spectra of liposomes, in particular 1H-13C chemical shifts correlations have been obtained on fluid lipid bilayers made of pure phospholipids for several years. We have investigated herein the possibility to obtain high resolution 2D MAS spectra of cholesterol embedded in membranes, i.e. on a rigid molecule whose dynamics is characterized mainly by axial diffusion without internal segmental mobility. The efficiency of various pulse sequences for heteronuclear HETCOR has been compared in terms of resolution, sensitivity and selectivity, using either cross polarization or INEPT for coherence transfer, and with or without MREV-8 homonuclear decoupling during t1. At moderately high spinning speed (9 kHz), a similar resolution is obtained in all cases (0.2 ppm for 1H(3,4), 0.15 ppm for 13C(3,4) cholesterol resonances), while sensitivity increases in the order: INEPT < CP(x4) < CP + MREV. At reduced spinning speed (5 kHz), the homonuclear dipolar coupling between the two geminal protons attached to C(4) gives rise to spinning sidebands from which one can estimate a H-H dipolar coupling of 10 kHz which is in good agreement with the known dynamics of cholesterol in membranes. 相似文献