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  • 1
    Electronic Resource
    Electronic Resource
    Theoretical analysis of molecular polarizabilities and polarizability derivatives in hydrocarbons (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 2424-2432 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Molecular polarizabilities and polarizability derivatives associated with CH and CC bond stretching have been calculated for CH4, C2H2, C2H4, C2H6, C3H6, C3H8, C4H8 (trans and gauche), C5H12 (all-trans) and C6H12. Self-consistent field calculations have been performed with several basis sets, principally the Dunning contractions of the Huzinaga bases with additional polarization functions. The polarizability derivative associated with a CH bond stretch varies significantly with the orientation and position of a bond within a molecule. Results are in agreement with parameters obtained from Raman trace scattering cross sections. A similar orientational dependence appears for the CC bond stretches of alkanes. There is a linear correlation between the molecular volume calculated with the proaim program and the molecular polarizability. Group polarizabilities (CH3 and CH2) are transferable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457001
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  • 2
    Electronic Resource
    Electronic Resource
    The harmonic force field of propane (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 3332-3340 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The quadratic vibrational force field of propane has been obtained by scaling calculated ab initio force fields to fit well determined vibrational frequencies from the Raman and infrared spectra of gaseous propane-h8, propane-d8, 1,1,1,2,3,3,3-propane-d7, and the two rotational isomers of 1,1,2,2,3,3,3-propane-d7. Two different ab initio force fields were investigated, one using Hartree–Fock theory (HF/6-31G*) and the other including electron correlation effects by means of second-order Møller–Plesset perturbation theory (MP2/6-31G*). The scaled MP2/6-31G* force field gives a significantly better fit of the experimental frequencies, especially for those involving contributions from the CC stretching coordinate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453027
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  • 3
    Electronic Resource
    Electronic Resource
    Harmonic force field and Raman trace scattering intensity parameters for cyclohexane (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 1509-1519 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Absolute Raman trace scattering cross sections have been measured for gaseous cyclohexane-h12, cyclohexane-d12, and the axial and equatorial isomers of cyclohexane-d11. A set of ∂α¯/∂Sj intensity parameters were determined from the experimental cross sections. The quadratic vibrational force field required for this analysis was obtained by scaling an ab initio force field to fit well determined vibrational frequencies. The unexpected intensity ratio observed for the CH stretching bands of the two conformers of d11 is explained by a difference in the ∂α¯/∂rCH value for the axial and equatorial CH bonds. The transferability of Raman intensity parameters is considered in light of recent results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453261
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  • 4
    Electronic Resource
    Electronic Resource
    Raman trace scattering intensity parameters for propane (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 3341-3346 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Absolute Raman trace scattering cross sections have been measured for gaseous propane-h8, propane-d8, 1,1,1,2,3,3,3-propane-d7, and the two rotational isomers of 1,1,2,2,3,3,3-propane-d7. A set of ∂α¯/∂Sj intensity parameters were determined from the experimental cross sections and compared with the ones obtained from quantum chemistry calculations. The anomalous intensity ratio observed for the CH stretching bands of the two conformers of CHD2CD2CD3 is explained by an unanticipated difference in the ∂α¯/∂rCH value for the two types of methyl CH bonds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453028
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  • 5
    Electronic Resource
    Electronic Resource
    Analysis of Raman trace scattering intensities in alkanes with the theory of atoms in molecules (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 9669-9677 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper, we report the detailed ab initio analysis of charge flow that occurs within a molecule during a molecular vibration, under conditions corresponding to a Raman experiment. Theoretical values for the molecular polarizability and polarizability derivatives are obtained in two ways for methane, ethane, and propane. Initially they are obtained from ab initio molecular orbital calculations employing coupled perturbed Hartree–Fock theory. Second, wave functions corresponding to the molecule in the presence and in the absence of an electric field, generated by the calculation, are analyzed according to the theory of atoms in molecules (AIM). The molecular polarizabilities are determined from the amount of charge transferred from one atom to another plus a contribution from reorganization of atomic charge within each atom, due to the presence of an electric field. Derivatives are obtained from the change in the molecular polarizability as the atoms are displaced from their equilibrium positions. It is apparent that a molecule behaves like a dielectric material, developing a depolarizing surface charge while atomic dipoles of interior atoms oppose the charge transfer. For nonspherical molecules, the polarizability derivatives for the symmetric CH stretching modes show considerable dependence on the orientation of the bonds with respect to the principal axes of the molecular polarizability, and hence, the carbon chain. The polarizability derivatives are characterized as arising from the atom-to-atom charge transfer or changes in the induced atomic dipoles. Previously observed dependence of the intensity on bond orientation is due, in large part, to charge transfer along a carbon chain. It is greatest for the terminal CH bonds lying in the plane of the carbon chain and increases regularly with chain length. The question of transferability of intensity parameters from one molecule to another, as is assumed in the bond polarizability model, is addressed in the light of this new information.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464345
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  • 6
    Electronic Resource
    Electronic Resource
    Vibrational analysis of CD3CD2CD3, CD3CHDCD3, and CHD2CD2CD3 in the 100–11 500 cm−1 spectral range (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 549-560 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Raman scattering (100 to 3000 cm−1) and infrared absorption spectra (500 to 11 500 cm−1) of CD3CD2CD3, CD3CHDCD3, and CHD2CD2CD3 are reported and analyzed. The major features of the overtone region can be explained on the basis of coupling between overtones of C–H stretching vibrations and CHD deformation vibrations. Fermi resonance coupling interactions become stronger with increasing overtone number up to ΔvCH=3. This coupling is analyzed for CD3CHDCD3. Implications for C–H stretching frequency and C–H bond length correlation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450601
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  • 7
    Electronic Resource
    Electronic Resource
    Intensity parameters for the Raman trace scattering of ethane (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 4290-4296 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Absolute Raman trace scattering cross sections have been measured for gaseous ethane-h6 and -d6 and the two rotational conformers of 1,1,2,2-ethane-d4. Sets of ∂α¯/∂Sj intensity parameters were determined for the C2H6/C2D6 pair and for the two CHD2CHD2 isomers; these sets were equal to within the experimental accuracy. The concept of an isotopically independent set of Raman intensity parameters for describing the Raman spectrum of various isotopic species of a molecule is found to be as valid as the concept of an isotopically independent harmonic force field for describing vibrational frequencies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451802
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  • 8
    Electronic Resource
    Electronic Resource
    Transport of metal complex chlorides through plastic film membrane (1977)
    [s.l.] : Nature Publishing Group
    Nature 268 (1977), S. 323-324 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Our all-glass diffusion apparatus consisted of two equal volume flanged cells with top openings for sampling. The 125-um polyurethane film (ether type) was sealed vertically between the two glass flanges with high vacuum Silicone or Kel-F grease and clamped. Platinum electrodes sealed in glass were ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/268323a0
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  • 9
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    Effect of Structure and Conformation on Raman Trace Scattering Intensities in Hydrocarbons (1998)
    American Chemical Society
    Details
    Publication Date: 1998-04-01
    Print ISSN: 1089-5639
    Electronic ISSN: 1520-5215
    Topics: Chemistry and Pharmacology , Physics
    Published by American Chemical Society
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  • 10
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    Analysis of Raman trace scattering intensities in alkanes with the theory of atoms in molecules (1993)
    American Institute of Physics
    Details
    Publication Date: 1993-06-15
    Print ISSN: 0021-9606
    Electronic ISSN: 1089-7690
    Topics: Chemistry and Pharmacology , Physics
    Published by American Institute of Physics
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