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1.
Neutron diffraction studies of the isotopes of chloroform CD35Cl3 and CD37Cl3 in liquid phase were carried out at 20°C and a wavelength of 0·7 Å. The data were corrected for background, absorption, multiple scattering and inelastic effects. The coherent distinct differential cross section was separated into intramolecular and intermolecular contributions. The latter, together with intermolecular contributions from neutron scattering data on chloroform of natural isotopic chlorine composition and from X-ray data, was employed to determine four expansion coefficients of the molecular pair correlation function. 相似文献
2.
Lovas F. J. Belov S. P. Tretyakov M. Y. Stahl W. Suenram R. D. 《Journal of Molecular Spectroscopy》1995,170(2)
The rotational spectrum of (CH3OH)2 has been observed in the region 4-22 GHz with pulsed-beam Fabry-Perot cavity Fourier-transform microwave spectrometers at NIST and at the University of Kiel. Each a-type R(J), Ka = 0 transition is split into 15 states by tunneling motions for (CH3OH)2, (13CH3OH)2, (CH3OD)2, (CD3OH)2, and (CD3OH)2. The preliminary analysis of the methyl internal rotation presented here was guided by the previously developed multidimensional tunneling theory which predicts 16 tunneling components for each R(J) transition from 25 distinct tunneling motions. Several isotopically mixed dimers of methanol have also been measured, namely 13CH3OH, CH3OD, CD3OH, and CD3OD bound to 12CH3OH. Since the hydrogen bond interchange motion (which converts a donor into an acceptor) would produce a new and less favorable conformation from an energy viewpoint, it does not occur and only 10 tunneling components are observed for these mixed dimers. The structure of the complex is similar to that of water dimer with a hydrogen bond distance of 2.035 Å and a tilt of the acceptor methanol of 84° from the O-H-O axis. The effective barrier to internal rotation for the donor methyl group of (CH3OH)2 is ν3 = 183.0 cm−1 and is one-half of the value for the methanol monomer (370 cm−1), while the barrier to internal rotation of the acceptor methyl group is 120 cm−1. 相似文献
3.
Although the vibrational spectra and force constants of CH3CN and CD3CN have been thoroughly studied, partially deuterated methyl cyanide has received much less attention. The infrared spectrum of CD2HCN has only recently been reported1 and that of CH2DCN has not yet appeared. Normal coordinate analysis for neither partially deuterated species has appeared. We report here harmonic frequencies and potential energy distributions for both partially deuterated methyl cyanide species, CH2DCN and CD2HCN, based on force fields and structural parameters from CH3CN and CD3CN. The calculated frequencies for CD2HCN are compared with the observed infrared frequencies. The vibrational interaction of the relatively high CN stretching frequency and the CD stretching frequencies is also discussed. 相似文献
4.
The transitions J = 1 ← 0, K = 0; J = 2 ← 1, K = 0; and J = 2 ← 1, K = 1 of CH3I and CD3I were measured using a Stark-modulated microwave spectrometer. Iodine quadrupole coupling strengths were analyzed to determine variations with deuterium substitution on the methyl group and variations with centrifugal distortion. Quadrupole coupling strengths were described by the expression . Explicit expressions are given for a, b, and c for a symmetric top in terms of molecular parameters. For CH3I eQq0 = ?1934.11 ± 0.02 MHz and for CD3I eQq0 = ?1928.95 ± 0.04 MHz. Rotational constants obtained are B(CH3I) = 7501.274 ± 0.002 MHz and B(CD3I) = 6040.298 ± 0.007 MHz. The observed fractional change in halogen quadrupole coupling of 0.0027 is related to previous results for methyl chloride and methyl bromide. 相似文献
5.
Neutron-diffraction studies on liquid acetonitrile CD3C15N at 20°C were carried out at neutron wavelengths of 0·5 Å and 0·7 Å. The data were corrected for background, absorption, multiple scattering and inelastic effects (Placzek correction) and then were normalized to absolute differential cross section by comparison with vanadium standard. The absolute coherent distinct differential cross section was separated into intermolecular and intramolecular contributions. From the latter the molecular structure in the liquid was determined. 相似文献
6.
E. C. C. Vasconcellos A. Scalabrin F. R. Petersen K. M. Evenson 《International Journal of Infrared and Millimeter Waves》1981,2(3):533-539
Twenty-four new submillimeter laser lines in fully deuterated methyl alcohol (CD3OD) in the wavelength range from 52 to 328 m have been obtained in a Fabry-Perot FIR resonator by optically pumping the methanol with a cw CO2 laser. We have made accurate wavelength measurements and have determined the relative polarization of most of the known CD3OD laser lines. The frequencies of 13 of the strongest lines were also measured.Contribution of the U.S. Government, not subject to copyright. 相似文献
7.
Samples of CH3CH2D, CH3CHD2, CD3CH2D, and CD3CHD2 have been prepared, and their infrared spectra recorded. Analysis of type B or type C “perpendicular” bands has enabled the rotational parameter () to be determined for all four species. These have been combined with existing infrared, Raman, and microwave data for CH3CH3, CD3CD3, and CH3CD3 species, to determine the ground state (r0) and ground state average (rz) structures within narrow limits. Zero point energy effects on the average structure are determined to be a CH bond shortening of 0.0015(3) Å and an HCC angle opening of 0.010(5)° on deuteration. These effects enable the equilibrium structure of ethane to be estimated. The rz(CC) bond length is determined to be 1.5351(2) Å, which is significantly longer than previous estimates involving electron diffraction data. 相似文献
8.
E.C.C. Vasconcellos C. DiRocco B. Chuzles J. Knier J. Schwalbe D. Sutton M. Jackson 《Applied physics. B, Lasers and optics》2003,77(1):97-99
Hydrazine (N2H4) and the deuterated isotopes of difluoromethane (CD2F2) and methanol (CH3OD and CD3OH) have been reinvestigated as sources of far-infrared (FIR) laser emissions using an optically pumped molecular laser system designed for wavelengths below 150 microns. With this system, seven FIR laser emissions from optically pumped N2H4, CH3OD and CD3OH were discovered with wavelengths ranging from 54.0 to 185.0 m. In addition, the polarizations of eight previously observed laser emissions from optically pumped N2H4, CH3OD and CD2F2 were measured for the first time. All laser emissions are reported with their operating pressures, relative polarizations and wavelengths, measured to ±0.5 m. The effectiveness of this particular system in generating short-wavelength laser emissions has been further demonstrated by the improvement in output power observed from nine known FIR laser emissions. PACS 07.57.Hm; 42.55.Lt 相似文献
9.
The J = 0 ← 1 transitions in CH379Br (I), CH381Br (II), CD379Br (III), and CD381Br (IV) were measured using a Stark-cell spectrometer constructed from C-band waveguide. High-resolution spectra yielded precise values for the bromine quadrupole coupling strength. Values obtained were eqQ(I) = ?577.08 ± 0.15 MHz, eqQ(II) = ?482.18 ± 0.15 MHz, eqQ(III) = ?575.66 ± 0.15 MHz, and eqQ(IV) = ?480.89 ± 0.15 MHz. The observed center frequencies for the J = 0 ← 1 transitions are ν0(I) = 19136.35 ± 0.03 MHz, ν0(II) = 19063.62 ± 0.03 MHz, ν0(III) = 15429.23 ± 0.03 MHz, and ν0(IV) = 15362.41 ± 0.03 MHz. A 0.26 ± 0.02% decrease in bromine quadrupole coupling is observed when the methyl group is fully deuterated. This is in agreement with, and supports interpretations given for, previous results on methyl chloride. 相似文献
10.
J. Demaison J. Burie J.M. Denis B.P. Van Eijck 《Journal of Molecular Spectroscopy》1984,107(2):250-260
The ground state millimeter-wave spectra of CH3NCH2 and CD3NCD2 have been measured. The rotational constants, centrifugal distortion constants, and barrier hindering internal rotation of the methyl group have been determined for both species. For the parent species Iα and ?(i,a) were also obtained, and for the perdeuteriated species the quadrupole coupling constants of 14N were determined. 相似文献
11.
The effect of benzo‐annelation on intermolecular hydrogen bond and proton transfer of 2‐methyl‐3‐hydroxy‐4(1H)‐quinolone in methanol: A TD‐DFT study
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Yanliang Zhao Meishan Wang Panwang Zhou Chuanlu Yang Xiaoguang Ma Zhe Tang Dongshuai Bao 《Journal of Physical Organic Chemistry》2018,31(5)
Excited‐state intermolecular or intramolecular proton transfer (ESIPT) reaction has important potential applications in biological probes. In this paper, the effect of benzo‐annelation on intermolecular hydrogen bond and proton transfer reaction of the 2‐methyl‐3‐hydroxy‐4(1H)‐quinolone (MQ) dye in methanol solvent is investigated by the density functional theory and time‐dependent density functional theory approaches. Both the primary structure parameters and infrared vibrational spectra analysis of MQ and its benzo‐analogue 2‐methyl‐3‐hydroxy‐4(1H)‐benzo‐quinolone (MBQ) show that the intermolecular hydrogen bond O1―H2?O3 significantly strengthens in the excited state, whereas another intermolecular hydrogen bond O3―H4?O5 weakens slightly. Simulated electron absorption and fluorescence spectra are agreement with the experimental data. The noncovalent interaction analysis displays that the intermolecular hydrogen bonds of MQ are obviously stronger than that of MBQ. Additionally, the energy profile analysis via the proton transfer reaction pathway illustrates that the ESIPT reaction of MBQ is relatively harder than that of MQ. Therefore, the effect of benzo‐annelation of the MQ dye weakens the intermolecular hydrogen bond and relatively inhibits the proton transfer reaction. 相似文献
12.
Continuous wave and pulsed 1H N.M.R. data have been obtained for solid H3GaN(CH3)3 over the temperature range 63–300 K. A theoretical expression for the relaxation behaviour of a methyl group in a trimethylamine moeity undergoing various motions has been obtained to aid analysis of the data. We find the activation energy to rotation of the -GaH3 group to be 3·6 ± 0·3 kJ/mole (0·86 ± 0·07 kcal/mole), and to a different motion in the molecule to be 21 ± 2 kJ/mole (5·0 ± 0·5 kcal/mole). In the continuous wave spectra effects due to motion of the -CH3 groups and the whole -NMe3 moeity may be distinguished. 相似文献
13.
This work gives an extensive critique of studies on methyl bromide and all its isotopic varieties with special stress on their rotational, vibrational, and rovibrational spectra. The rotational constants of more than 40 vibrational states of CH3Br and 20 of CD3Br, as well as of the ground states of all varieties, were critically examined and corrected where needed. An almost complete set of harmonic and anharmonic constants for CH3Br was derived. From the set of rotation-vibration interaction constants, new accurate equilibrium constants Ae and Be have been evaluated for CH379Br, CH381Br, CD379Br, CD381Br, from which the following equilibrium structure is obtained: re(C---H) = 1.0823 Å; re(C---Br) = 1.9340 Å; α(HCH) = 111.157°. 相似文献
14.
The Raman and infrared spectra of (CH3)2Cd and (CH3)2Zn have been reexamined and are reported along with previously unreported vibrational data for (CD3)2Cd and (CD3)3Zn. The spectra have been analyzed using the double group , which has led to some changes in assignments made previously. Comparison is also made with a recent study of (CH3)2Hg and (CD3)2Hg. Fine structure was observed for two of the vibrations of the E1d symmetry species, arising from internal rotation of the methyl groups. This structure has been analyzed using a recently developed theory for molecules of the freely rotating dimethylacetylene type. Problems which arise in the application of this theory have been pointed out, and it is suggested that some additional consideration of the theory may be necessary. 相似文献
15.
J. Dupre-Maquaire J. Dupre C. Meyer J. G. Lahaye A. Fayt 《International Journal of Infrared and Millimeter Waves》1986,7(8):1213-1239
Infrared spectra of theV
2 andV
5 bands of CD3Cl have been recorded with a resolution of about 0.015 cm–1 and assigned. Moreover Stark patterns of the trideuterated methyl chloride for two CO2 laser lines with saturated Lamb dips have been analysed. Many new strong coincidences showing hyperfine structure are observed and assigned. 相似文献
16.
Rampur S. Viswanath Philip J. Miller Charles A. Cody 《Journal of Physics and Chemistry of Solids》1979,40(3):223-229
IR transmission, near-normal IR reflection and polarized Raman spectra of single crystals of selenious acid (H2SeO3) have been obtained at temperatures between 77°K and 335°K. The observed bands in the O-H stretching region have been assigned to two types of O-H….O bonds in the crystal structure. The spectral results appear to rule out correlation field splittings, intramolecular coupling, or Fermi resonance as explanations for the observed splitting. A proposed model based on intermolecular coupling of O-H….O vibrations to explain the splitting of the O-H stretching region is given. 相似文献
17.
运用约化维数量子动力学理论,利用含时波包法,对反应D+CD4→CD3+D2进行了四维量子散射计算.将反应多原子CD4看作双原子D—CD 3,反应D+CD4→CD3+D2看作单原子-双原 子反应,把体系的反应简化为四维散射问题. 波函数的传播采用分裂算符法,为避免格点边界处含时波函数的边界反射,采用了光学吸收 势法,在格点边界处引入光学势,消除边界反射.根据CD4分子的C3v对称性, 选取了Jordan和Gilbert提出的半经验势能面.计算结果表明,反应概率随平动能的变化图像 ,呈现出显著的量子共振特性,这是很多提取反应的共同特征.而不同振动态下的反应概率 随平动能的变化表明,随振动量子数的增大,反应概率有明显提高,且反应阈能明显降低, 这说明反应分子的振动能对分子的碰撞反应有重要贡献.而对基态和第一振动激发态时散射 截面的计算,也证明了这一结论.同时,还分别通过计算量子数j,k,m对反应概率的影响, 对该反应的空间取向效应进行了研究,并与H+CH4→CH3+H2 sub>反应进行了比较.
关键词:
含时波包
量子散射
反应概率 相似文献
18.
Neutron scattering experiments have been performed on liquid difluoromethane (CH2F2, R32) resulting in the first experimental determination of the total structure factor and total pair distribution function of difluoromethane. Analysis of the measurements has led to the liquidstate intramolecular structure of this fluid. The structure has been compared with that obtained for some other halogenated methanes. A comparison with results obtained for trifluoromethane (CHF3, R23) suggests that there is less long-range order in liquid-state difluoromethane than trifluoromethane. Subtraction of the intramolecular structure leads to an intermolecular structure factor and an intermolecular pair distribution function, both of which are crucially important for assessing the reliability of models of the pair potentials used in computer simulations. 相似文献
19.
《Journal of Molecular Spectroscopy》1987,122(1):1-8
Microwave spectra of methylsilylsulfide and its three isotopically substituted species were measured and their b-type transitions were assigned. The spectra of all the species exhibit doublet structures due to the internal rotation of the methyl group. Using the internal axis method, the potential barriers were determined from the observed A- and E-component frequencies to be 1081.0 ± 3.3, 1073.9 ± 2.0, 1065.1 ± 11.4, and 1076.0 ± 1.9 cal/mol for the normal, CH3SSiD3, CD3SSiH3, and 13CH3SSiH3 species, respectively. The analysis also yielded 3°49′ as the tilt angle of the methyl top. From the rotational constants obtained, a plausible structure was estimated. The molecular electric dipole moments were determined from the second-order Stark effect of some A-component transitions with low- J quantum numbers for the normal and SiD3 species. A comparison of the obtained parameters was made with analogous molecules. 相似文献
20.
Microwave spectra of dimethyl ether, dimethyl sulfide, and dimethyl silane in the torsionally excited states have been measured. The methyl internal rotations of these molecules were analyzed from the observed multiplets and from the reported multiplets of transitions. The method developed for ethyl silane in the previous paper was extended to equivalent two top molecules. For equivalent two top molecules, apparent barriers of methyl internal rotations obtained from the experiments were corrected by the kinetic and potential cross terms. They are V3=2645.8±10.0, 2632.4 ± 42.9, 2146.0 ± 13.8, 1651.5 ± 10.1, 1648.0 ± 13.7, and 1649.9 ± 11.8 cal/mol for (CH3)2O, (CD3)2O, (CH3)2S, (CH3)2SiH2, (CH3)2SiD2, and (CH3)2SiHD, respectively. The potential cross terms, V12(1−cos3α1)(1−cos3α2) terms are negligible for the three molecules, while V′12sin3α1sin3α2 terms are also very close to zero except those for (CH3)2O and (CD3)2O which are small but not negligible (V′12=−124.4,−158.0 cal/mol). The investigations were extended to those of non-equivalent two top species and the corrected barriers of the methyl tops, V3, are obtained to be 2615.6 ± 8.6 and 2155.0 ± 15.2 cal/mol for CH3OCD3 and CH3SCD3. The corrected barrier, V3(CD3) of CH3OCD3, is obtained to be 2634.4 ± 7.1 cal/mol, while that of CH3SCD3 cannot be solved due to the lack of the data available. 相似文献