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1.
Munetaka Nakata Kunio Kohata Tsutomu Fukuyama Kozo Kuchitsu 《Journal of Molecular Spectroscopy》1980,83(1):105-117
The rz structure of phosgene has been determined by a joint analysis of the electron diffraction intensity and the rotational constants as follows: , , ∠z;ClCCl = 111.83 ± 0.11°, where uncertainties represent estimated limits of experimental error. The effective constants representing bond-stretching anharmonicity have been obtained from an analysis of the isotopic differences in the rz structure: , . The equilibrium bond distances have been estimated from the rz structure for the normal species and from the anharmonic constants to be , . 相似文献
2.
The microwave spectrum of the unstable thiocarbonyl thioketen, H2CCS, has been investigated in the region 26.5–40 GHz. All singly substituted species as well as D2CCS have been studied and the derived rotational constants yield the following structural parameters: , , , ∠s(HCH) = 120.3 ± 0.5°. The dipole moment is μ = 1.02 ± 0.01 D. Four low frequency vibrational modes have been observed and their assignments are discussed. 相似文献
3.
Munetaka Nakata Tsutomu Fukuyama Kozo Kuchitsu Harutoshi Takeo Chi Matsumura 《Journal of Molecular Spectroscopy》1980,83(1):118-129
The microwave spectra of eight isotopic species of COCl2 have been observed, and the following rotational constants have been obtained: An analysis of the rotational constants has resulted in the rs and rm structures. The equilibrium structure, re, has been estimated by combining the rm parameters derived according to Watson's method and the re bond distances estimated in our recent electron-diffraction and spectroscopic studies to be , , ∠eClCCl = 111.79 ± 0.24°. 相似文献
4.
The microwave and photoelectron spectra of isocyanato ethene CH2CHNCO have been studied. The microwave results indicate that the species is planar and possesses both a cis and a trans form. The appearance of dense and complicated vibrational satellite lines indicates that the molecule is quite flexible, a general property of molecules containing the isocyanate group. The rotational constants are: These constants are shown to be consistent with structures in which , ∠(CCN) = 122 ± 1° (for both conformers), and ∠(CNC) = 142.4 ± 0.5° (cis) and 138.4 ± 1.5° (trans). The dipole moments are μ(cis) = 2.120 ± 0.015 and μ(trans) = 2.207 ± 0.007 D. Several distinct peaks are observed in the photoelectron spectrum; however, the structure is not resolved into features belonging to the different isomers. The first ionization potential lies at 9.80 ± 0.1 eV. The spectrum has been assigned with the aid of theoretical calculations. 相似文献
5.
The microwave spectra of the two natural isotopic species of cis-1-chlorobutadiene-1,3, CH35ClCHCHCH2 and CH37ClCHCHCH2, together with all monosubstituted species with deuterium or 13C isotopes have been measured and assigned and the complete substitution structure has been determined. The spectral region investigated was between 18 and 40 GHz. The molecule was found to be planar and the following values were found for the principal parameters: r(CC)chlorovinyl = 1.327(6), , <(CCC)chlorovinyl = 126.5(3)° and <(CCC)vinyl = 123.0(7)°. The nuclear quadrupole coupling constants, χaa and χbb, for the parent molecule were calculated and further used to estimate the symmetry of the field gradient around the CCl bond. Force-field calculations were used to predict the centrifugal distortion constants and inertial defect of some isotopic species. Thermodynamic functions were calculated for cis- and trans-1-chlorobutadiene-1,3 and used to estimate the energy difference between them. 相似文献
6.
The J = 4 ← 3 and J = 3 ← 2 rotational transitions of 1-phosphapropyne, CH3CP, between 26.5 and 40 GHz have been studied by microwave spectroscopy. The spectrum shows the characteristic vibration-rotation satellite patterns associated with a C3v symmetric rotor. Apart from the most abundant isotope variant, the species 12CD312C31P, 12CD2H12C31P, 12CH2D12C31P, 13CH312C31P, 12CH313C31P, 13CD312C31P, and 12CD313C31P have also been studied. For 12CH312C31P the rotational constants B0 = 4991.339 ± 0.003 MHz, DJ = 0.823 ± 0.092 kHz, DJK = 66.59 ± 0.18 kHz have been determined. From these data the following structural parameters have been derived: , ∠s(HCC) = 110.30 ± 0.09°, , . The dipole moment has been determined as 1.499 ± 0.001 D by analysis of the Stark effect of the J = 3 ← 2, |K| = 1 line. The vibrational satellites (vs = 1, 2, and 3) have been studied and various vibration-rotation parameters derived. 相似文献
7.
A. Baldacci S. Ghersetti S.C. Hurlock K. Narahari Rao 《Journal of Molecular Spectroscopy》1976,59(1):116-125
The rotational structure of about 40 bands of 12C2HD observed in the region 6000?600 cm?1 has been measured and interpreted with the purpose of determining a comprehensive set of molecular constants for this isotopic variety of acetylene. Combining these data with the results for 12C2H2 and 12C2D2, a reevaluation of the equilibrium internuclear distances for the acetylene molecule has been made: and were obtained. This paper presents all the molecular constants derived in this study. 相似文献
8.
Cyanobutadiyne (cyanodiacetylene), HCCCCCN, is sufficiently stable at low pressures to permit its rotational spectrum to be studied by microwave spectroscopy. The spectrum consists of a series of R-branch transitions typical of a linear molecule. The transitions with J = 9 to 14 which lie between 26.5 and 40.0 GHz have been measured for the vibrational ground state. Transitions have also been detected in natural abundance for all possible singly substituted 13C and 15N isotopic species. Deuteriated cyanobutadiyne, DCCCCCN, has also been synthesized and its ground state spectrum recorded. These measurements have enabled a complete substitution structure to be derived for the first time for a polyacetylene: r8(HCa) = 1.0569 ± 0.001, r8(CaCb) = 1.2087 ± 0.001, r8(CbCc) = 1.3623 ± 0.003, r8(CcCd) = 1.2223 ± 0.004, r8(CdCe) = 1.3636 ± 0.003, . The spectroscopic parameters for the ground state are B0 = 1331.3313 ± 0.001 MHz and D0 = 0.0257 ± 0.002 KHz. The dipole moment, determined from the Stark effects of the J = 9 and 10 lines, is 4.33 ± 0.03 Debye. 相似文献
9.
A millimeter-wave spectrometer having a sensitivity of 4 × 10?10 cm?1 in the 2-mm region has been constructed for observation of extremely weak millimeter-wave spectra of gases. It has been used to measure J → J, K = 0 ← 3 transitions in PH3 and J → J, K = 0 ← 3 as well as K = ±1 ← ±4 transitions in PD3. The B0 and C0 spectral constants (in MHz) are: for PH3, B0 = 133 480.15 ± 0.12 and C0 = 117 488.85 ± 0.16; for PD3, B0 = 69 471.10 ± 0.03 and C0 = 58 974.37 ± 0.05. The effective ground-state values obtained for the bond angle and bond length are: for PH3, and ; for PD3, and . The corresponding zero-point-average values were calculated to be: for PH3, and ; for PD3, and . For both species, the equilibrium values are and . 相似文献
10.
Nigel D Sanders 《Journal of Molecular Spectroscopy》1981,86(1):27-42
The microwave spectrum of methylmalonaldehyde has been measured and the molecule shown to be in an intramolecularly hydrogen-bonded (chelate ring) form in the gas phase. The spectrum shows the effects of two large amplitude internal motions: the torsion of the methyl group about its symmetry axis and the tunneling of the hydrogen-bond hydrogen through a potential barrier to an equivalent position (combined with an appropriate CH3 rotation). The two motions are coupled through the torsion-inversion potential energy term of threefold symmetry in the torsional coordinate. A two vibration-plus-rotation model is developed and applied to explain the sizeable perturbations of the pure rotational transitions from a rigid rotor pattern in four ground-state sublevels. The observed torsion-inversion splittings in the nondegenerate level (2.8004 cm?1 for , 0.35920 cm?1 for and 0.92590 cm?1 for are quite well determined and, as expected, depend strongly upon appropriate isotopic substitutions. The experimentally derived parameters are discussed in terms of an effective inversion-torsion potential surface. The data are not in disagreement with a range of barrier values determined from comparison of ab initio full geometry-optimized and constrained C2v geometry-optimized molecular orbital calculations. Because of the expected isotope dependence of the effective surface and the large number of parameters involved, it is not clear whether more accurate fitting to the data is justified. 相似文献
11.
William M. Stigliani Victor W. Laurie L.H. Scharpen 《Journal of Molecular Spectroscopy》1976,62(1):85-89
The microwave spectra of the 18O and the α,α,α′,α′-tetradeuterated isotopic species of cyclobutanone have been investigated. Structural parameters determined are , , ∠ HαCHα = 109.2 ± 1° with the methylene group tilted toward the carbonyl group by 4.6 ± 0.8°. 相似文献
12.
Yoshiyuki Kawashima Harutoshi Takeo Chi Matsumura 《Journal of Molecular Spectroscopy》1979,78(3):493-505
Fluorohydroxy borane, BF(OH)2, has been identified in the hydrolysis of trifluoroborane by microwave spectroscopy. The rotational and centrifugal distortion constants have been determined for the normal and d2 species. From these constants the molecular structure has been determined. This molecule does not have C2 symmetry and the structural parameters are , , ∠FBO1 = 118.2°, and ∠FBO2 = 121.0°. The inertia defects establish the planarity of the molecule. The dipole moment of 1.818 ± 0.007 D has been obtained from the measurements of the Stark effects. 相似文献
13.
Yasuki Endo Shuji Saito Eizi Hirota Toshio Chikaraishi 《Journal of Molecular Spectroscopy》1979,77(2):222-234
Microwave spectra of SF2 in the first excited states of the three normal modes were observed and analyzed. A comparison of the observed inertia defects in the ν1 and ν3 states with those calculated by omitting the contributions of the Coriolis interaction between the two modes led to a vibrational frequency differences of 25.72 ± 0.33 cm?1, with ν1 being definitely higher. The inertia defect in the ground state and our measured values for the inertia defect in the ν2 state and for the difference were combined with the centrifugal distortion constants of Kirchhoff et al. [J. Mol. Spectrosc.48, 157–164 (1973)] to improve the harmonic force field. The interaction constant between the two SF stretching coordinates was determined precisely. The third-order and the cubic anharmonic potential constants were calculated from the observed vibration-rotation constants. The equilibrium structure was determined to be and θe(FSF) = 98.048 ± 0.013°. 相似文献
14.
G.C. Salzman Gerald G. Ohlsen J.C. Martin J.J. Jarmer T.R. Donoghue 《Nuclear Physics A》1974,222(3):512-524
Angular distributions of six polarization transfer coefficients ; of the four analyzing powers Ay(θ), Axx(θ), Ayy(θ), and Azz(θ); and of the polarization function Pý(θ), have been measured atEd = 10.00 MeV for the reaction 2H(d, n)3He. Measurements were made for neutron lab angles between 0° and 80° in 10° steps. Additionally the y-axis associated quantities were measured at θ1ab = 99°. Most of the measured coefficients are large at some angles and all show considerable variation with angle. 相似文献
15.
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
16.
Ronald D Brown Peter D Godfrey Burkhard Kleibömer 《Journal of Molecular Spectroscopy》1985,114(2):257-273
An extensive study of the microwave spectrum of cyanamide has been undertaken, the analysis being based in part on semirigidbender calculations by the methods of Bunker and Szalay. Inversion lines of NH2CN, branches and a number of vibrational satellites of the J = 2?1 transition were observed. A two-vibrational-state Hamiltonian was used to fit simultaneously the 0+ and 0? microwave data and yielded rotational constants X, Y, Z, DJ, DJK, d1, HJK as well as the inversion splitting and the μyz-connecting matrix element. Vibrational satellite data of seven isotopic species and infrared frequencies of NH2CN were included in the semirigid bender calculations: The NCN spine is nonlinear by ca. 5° in the equilibrium structure of the molecule. Also, ; <HNH/2 = 60.39° ? 0.1134?2; (? is the inversion angle in rad); fixed. The inclusion of the NC bond flexing was necessary in order to reproduce the observed vibrational satellite patterns of NH2CN, NHDCN, and ND2CN. The barrier to inversion of the amino group is 510 ± 6 cm?1 with minima at ±45.0 ±0.2°. The inversion dipole moment is 0.91 ± 0.02 Debye. 相似文献
17.
The band structure of the dimerised trans-polyacetylene-chain (, , , is calculated with the (parameter-free, non-self-consistent) linear-combination-of-atomic-orbitals method using the Gáspár-Kohn-Sham (GKS) potential for the exchange and correlation. The calculated dimerisation gap of 1.6 eV agrees closely with experiment and also with other GKS calculations when the degree of dimerisation is taken into account. The calculated density of states agrees closely with the X-ray photoemission spectrum of Brundle. 相似文献
18.
G Cazzoli 《Journal of Molecular Spectroscopy》1974,53(1):37-44
A method based on the least-squares fitting of the observed vibrational frequencies, centrifugal distortion constants, mean-square amplitudes, and vibration-rotation interaction constants with respect to the harmonic force constants has been employed to determine the harmonic force field of NCl3 and PCl3. The results are compared with those obtained by other authors. An improved structure of PCl3 has also been determined by analysis of the microwave spectrum of the P37Cl3 and P35Cl237Cl isotopic species. Two structures have been obtained with the following values of the parameters 相似文献
19.
The results of a vibrational and rotational analysis of the banded transition in are presented. Only three of the six vibrational modes are active in the spectrum with , , and . The spin forbidden transition gains intensity primarily by a mixing of the and states. This is confirmed by a rotational analysis of the 000 band of both isotopes. The rotational analysis shows that the coupling in the state is near Hund's case b and that the spin constants are nearly 10 times greater than those observed for CH2O. A calculation shows that this difference is due to the greater spin orbit coupling of S in CH2S and to the smaller energy differences between the , , , and the states. The r0 structure calculated from the rotational constants is , , βHCH = 119.6°, and α (out of plane) = 16.0°. A simultaneous fit of the vibrational levels in ν′4 of CH2S and CD2S to a double minimum potential function yielded a barrier to molecular inversion of 13 cm?1 and an equilibrium out-of-plane angle of 15°. 相似文献
20.
The microwave spectra of the isotopic species K13CN and KC15N have been investigated by molecular beam electric resonance spectroscopy, using the seeded beam technique. For both isotopic species about 20 rotational transitions originating in the ground vibrational state were observed in the frequency range 9–38 GHz. The observed transitions were fitted to an asymmetric rotor model to determine the three rotational, as well as the five quartic and three sextic centrifugal distortion constants. The hyperfine spectrum of KCN has been unravelled with the help of microwave-microwave double-resonance techniques. One hundred and forty hyperfine transitions in 11 rotational transitions have been assigned. The hyperfine structures of K13CN and KC15N were also studied. For all three isotopic species the quadrupole coupling constants and some spin-rotation coupling constants could be deduced. The rotational constants of the 13C and 15N isotopically substituted species of potassium cyanide, combined with those of the normal isotopic species (determined more accurately in this work), allowed an accurate and unambiguous evaluation of the structure, which was confirmed to be T shaped. Both the effective structure of the ground vibrational state and the substitution structure were evaluated. The results for the effective structural parameters are , , and . The values obtained for the principal hyperfine coupling constant eQqz(N), the angle between the CN axis and zN, and the bond length rCN indicate that in gaseous potassium cyanide the CN group can be considered as an almost unperturbed CN? ion. 相似文献