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1.
In the infrared spectra of molecules with more than one C-H bond the symmetric and antisymmetric stretching bonds often overlap,
causing uncertainty in the intensity analysis. For CH2Cl2 and CD2Cl2 in the vapour state, the two bands overlap to such an extent that Straley who takes it as one band attributes it to antisymmetric
stretching while Saekiet al assign it to the symmetric stretching. Following the method of analysis initiated in this laboratory, we have solved this
problem by ultimately obtaining intensities separately forA
1 andB
2 species. The band is mostly due to the symmetric stretching, 0.06 out of the total of 0.31 contributing toB
2. Thus, this gives a method of separating the intensities of bands which are highly overlapping.
Presented at the Symposium on Crystallography and Crystal Physics, Osmania University, Hyderabad held on 5–7, December 1977. 相似文献
2.
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
3.
4.
Expressions involving vibrational frequencies, Coriolis coupling constants and masses of the atoms of the molecule that are
invariant under symmetrical isotopic substitutions are derived for octahedral XY6 molecules following the method given by Jagannathan and others. These invariants are used to calculate the force constants,
compliance constants and mean amplitudes of vibration of 13 molecules of XY6-type. 相似文献
5.
Infrared intensity analysis of MXY2 type molecules has been attempted. The dipole momentμ of C=O is obtained to be different for different moleculesviz. for CH2O, 1.9052; for COCl2, 1.1517; for COF2, 0.6340; and for COBr2, 0.7687. Similarly in the case of CSF2 and CSCl2
μ
C=S it was found to be 0.2473 and 0.2983 respectively. This shows that the effect of the electro-negative halogen atoms is very
important.
Presented at the ‘National Symposium on Molecular Spectroscopy’, Annamalai University, Annamalainagar on 28 February 1976. 相似文献
6.
使用日本原子能研究开发机构里设置的高分解能粉末中子衍射装置, 在 15 K 和 294 K 温度下对 PbS 进行了中子衍射实验。在 15 K 和 294 K 温度里观察到了明显的振动形状的热漫散射。 所观察到的漫散射强度可由原子间热振动相关效应的影响来解释。在 294 K 下从原子间相关效应和德拜—劳厄因子的温度参数中获得了 PbS 相邻原子间的力常数。 相似文献
7.
The infrared and Raman spectra of Cd(15NH3)2Cl2 are reported and a comparison is made between the normal and 2H isotope substituted compounds. A further refinement of the Local Symmetry Force Constants was carried out. 相似文献
8.
使用日本原子能研究开发机构里设置的高分解能粉末中子衍射装置,在15 K和294 K温度下对Pb S进行了中子衍射实验.在15 K和294 K温度里观察到了明显的振动形状的热漫散射.所观察到的漫散射强度可由原子间热振动相关效应的影响来解释.在294 K下从原子间相关效应和德拜-劳厄因子的温度参数中获得了Pb S相邻原子间的力常数. 相似文献
9.
It is suggested that force fields calculated for polyatomic molecules may be presented in dimensionless coordinates, ξ (=R/Re, where R is internal coordinate and Re is the equilibrium value of corresponding bond distance or angle). Stretching force constants when presented in dimensionless coordinates show interesting trends. It is found that whereas the force constants in terms of internal coordinates, Fii vary widely for bonds with different atoms in the series Z-H (Z:C, Si, Ge), Y-H (Y:N, P, As, Sb, O, S), X-H (X:F, Cl, Br, I), X-C etc, the corresponding force constants in dimensionless coordinates, Φii are same within the limits of experimental errors. It is felt that such force constants may have better prospects of transferability between related molecules and may be helpful in making the normal coordinate analysis easier to some extent. 相似文献
10.
11.
12.
The infrared and Raman spectra of the cadmium diammindichloride complexes with 2H isotopic substitution, have been measured. A normal coordinate analysis for the isotopic compounds has been carried out based on a Local Symmetry Force Field (LSFF). The results sup port the experimental assignments. 相似文献
13.
A method is proposed for the determination of angle parameters for ONF, ONCl and ONBr, utilising the isotopic frequencies
of two isotopically substituted molecules. The force constants, Coriolis coupling constants, inertia defect, mean amplitudes
of vibration and rotational distortion constants were also calculated and compared with literature values. 相似文献
14.
The infrared and Raman spectra of the cadmiumdiammindibromide with 2H - isotopic substitution, have been measured. In order to examine the transferabilities of the skeletal and -NH3, ligand force constants, a normal coordinate analysis was carried out based on a Local Symmetry Force Field (LSFF). The results support the experimental assignments. 相似文献
15.
We present here an approach for determining the Hamiltonian of polyatomic molecules that allows one to successfully solve the problem of potential energy surface (PES) determination via construction and diagonalization of a Hamiltonian matrix of large dimension. In the suggested approach, the Hamiltonian is very simple and can be used both for any “normal” polyatomic molecule and for any isotopic species of a molecule. Molecules with two to four equivalent X-Y bonds are considered, and for illustration of the efficiency of the suggested approach, numerical calculations are made for the three-atomic (hydrogen sulfide) and four-atomic (formaldehyde) molecules. 相似文献
16.
The force constants of XeO3F2 have been evaluated using the general valence force field. The mean square amplitudes of vibration, the generalised mean
square amplitudes and shrinkage constants, Coriolis coupling coefficients and centrifugal distortion constants have also been
calculated for the first time using the vibrational frequencies and the structural parameters. The thermodynamic properties
have been computed for the ideal gaseous state at 1 atmospheric pressure for 11 temperatures from 100° to 1000°K using a rigid
rotor harmonic oscillator approximation. 相似文献
17.
M. G. Krishna Pillai K. Ramaswamy S. G. Gnanadesikan 《Czechoslovak Journal of Physics》1966,16(2):150-156
A normal co-ordinate analysis of silylacetylene and silylacetylene-d
3 has been carried out following Wilson'sF-G matrix method. The potential energy constants obtained therefrom have been used to evaluate rotational distortion constants and mean square amplitudes of vibration for these molecules. Thermodynamic functions, such as heat content, free energy, entropy heat capacity for the ideal gaseous state at one atmosphere pressure and with the usual rigid rotor harmonic oscillator approximation, have also been calculated for 12 temperatures from 100°K to 1000°K. 相似文献
18.
The third-order elastic constants of single crystal GaSb are determined using ultrasonic pulse interferometer at 10 MHz. The
constants at 300°K, in units of 1011 N.m.−2, are Cl11 = ™ 4 ·75 ± 0·06 C144 = + 0·50 ± 0·25 C113 = ™ 3 ·08 ± 0·02 C166 = ™ 2·16 ± 0·13 C123 = ™ 0 ·44 ± 0·29 C456 = ™ 0·25 ± 0·15 These constants are used to evaluate the three anharmonic first and second neighbour force constants based
on modified Keating’s model. The constants are (in units of 1011 N.m−2)γ=− 2·406;δ=0·407;ε=−0·222. 相似文献
19.
Studies on dissociation energies of diatomic molecules using vibrational spectroscopic constants 总被引:4,自引:1,他引:3
New analytical expression and numerical approach are suggested to calculate dissociation energies De of diatomic molecular states using an extreme value method (EVM). Studies on some electronic states of OH, BH, N2, Br2, ClF and CO molecules show that the accuracy of the EVM dissociation energies depends on the number of correct vibrational constants used in the calculations. The convergence qualities of De are suggested to be an alternative physical criterion to measure the qualities of the various sets of vibrational constants from different literature for the same diatomic state. 相似文献
20.
A pulsed fast Fourier transform N.M.R. spectrometer is used to investigate the temperature dependence of the 13C chemical shifts in the nematic liquid crystal solutions of the following halides: 13CH3I, 13CH3Br, 13CH3Cl. The H-C-H bond angles are accurately measured in this investigation from proton magnetic resonance studies. The signs of the coupling constants D 13CH , D HH, J 13CH and the ordering parameter have been assigned to be all positive. The 13C magnetic shielding anisotropy is found to become more positive with the increasing electronegativity of the halogen substituents. The values of the anisotropies are: Δσ = σ ∥ - σ ⊥ = - 101 ± 15 p.p.m. (13CH3I), - 10 ± 5 p.p.m. (13CH3Br), 22 ± 5 p.p.m. (13CH3Cl). Results for Δσ obtained from the slope of σn versus S 33 agree with those obtained from the nematic-isotropic phase subtraction method. 相似文献