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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Chemistry of materials 6 (1994), S. 239-248 
    ISSN: 1520-5002
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 7251-7252 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 7001-7006 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Attachment energies of low energy electrons to Fe(CO)5 and to η4 complexes of 1,3-butadiene, 1,3-cyclohexadiene, cyclooctatetraene, and cyclobutadiene with Fe(CO3) have been determined by electron transmission spectroscopy. The spectrum of Fe(CO)5 is similar to that of Cr(CO)6, showing an anion resonance near threshold assigned to predominantly Fe3d orbitals and two resonances between 1 and 3 eV assigned to predominantly COπ* orbitals.The diene complexes show threshold features similar to Fe(CO)5, COπ* resonances around 2 eV, and one or more diene π* resonances. The resonances from the lowest π* orbitals of butadiene, cyclohexadiene, and cyclooctatetraene are little different in the free dienes and the complexes, but higher π* orbitals are substantially destabilized in the complexes, consistent with qualitative symmetry arguments. In the cyclobutadiene complex the π@B|3 orbital of cyclobutadiene is strongly destabilized by interaction with the Fe3d, giving a resonant feature at 1.2 eV. Dissociative attachment of electrons by the iron tricarbonyl complexes has been observed mass spectrometrically. The phenomenon is observed for electrons of energy less than 2 eV and results primarily in the loss of CO. For the cyclobutadiene complex, however, the attachment of 0 eV electrons results in a complex chemical process leading to the ejection of C2.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 4066-4069 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ab initio coupled Hartree–Fock perturbation theory (CHFPT) calculations on PF3, PF+4 , PF5, PF−6 , and PO3−4 using large polarized Gaussian bases satisfactorily reproduce observed 31P NMR chemical shifts. In PF3 the 31P NMR shielding constant σ increases as the P–F bond distance or the F–P–F angle is decreased. The 31P chemical shift δ of PF+4 is predicted to be ∼−15 ppm (vs 85% H3PO4). Although the average values of the isotropic NMR shieldings are overestimated by the calculations (e.g., σPav calc. 372.5 ppm vs expt. 259±20 ppm in PF3) the anisotropy in σP is well reproduced (calc. 244.7 ppm vs expt. 228±2 ppm). The ∼200 ppm smaller 31P NMR shielding of PF3 compared to PF5 arises partly from a diamagnetic contribution lower by ∼100 ppm and partly from the more negative paramagnetic contribution arising from mixing of the 8a1 P lone pair MO with unoccupied orbitals of e symmetry in PF3.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 4824-4824 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 5571-5576 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Valence orbital momentum distributions, ρ(q), are obtained for s-triazine, C3H3N3, from (e,2e) spectroscopy and split valence SCFMO calculations. The separation energy spectrum simulated using the calculated ρ(q) and ionization energies from Green's function calculations is in good agreement with experiment from 9–20 eV, but at higher energy the simulated spectrum has higher intensity than experiment, indicating that the Green's function calculation underestimates the complexity of the inner valence region. The calculated momentum distributions have their maxima at higher values than observed experimentally for the outermost valence orbitals, but the difference in momentum distributions between the antisymmetric 4e' N2p lone pair orbital of s-triazine and the N2p lone pair orbital of ammonia is reproduced well by the calculations. Similarly, calculated and experimental differences of Fourier transformed ρ(q) for the 4e' and 3a'1 N2p lone pair orbitals of triazine are in agreement and can be interpreted using plots of 4e' and 3a1 orbital averages and differences from the SCFMO calculations. The Fourier transformed momentum distribution of the 4e' orbital clearly shows the presence of both nearest-neighbor C and second-nearest-neighbor N interactions.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 1994-2001 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The distribution of electron momentum density has been measured for the outermost occupied orbitals of the vinyl halides and ethylene using the (e,2e) technique. In contrast to the ionization potentials for these π orbitals which decrease monotonically from vinyl fluoride to vinyl iodide, the values of the momenta where the distributions are a maximum, pmax, increase from the fluoride through the bromide and then shift back to a lower value for the iodide. This observation can be analyzed in terms of B(r), the Fourier transform of the observed momentum distribution, and ΔB(r), the difference between B(r) functions. The shape of ΔB(r) for the fluoride, chloride, and bromide in comparison to ethylene reflects the effect of the carbon–halogen antibonding interaction in these vinyl halides. On the other hand, in vinyl iodide the antibonding interaction is compensated for by the diffuse iodine 5p character of the molecular orbital. The relation of these observations to chemical properties of the vinyl halides is discussed along with differences between experiment and calculations at low momentum.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 25-33 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Relative momentum densities have been measured for the outermost occupied π orbitals of acetylene, propyne, 2-butyne, and perfluoro-2-butyne using the (e, 2e) technique with an improved multiple detector spectrometer. The results, when compared with suitably averaged quantum mechanical calculations, show systematic differences between the molecules which can be interpreted in terms of wave function averages and differences using the ΔB(r) functions. A striking feature of the data is the significant momentum density at zero momentum for all of the molecules, in contrast to the calculations that all show zero momentum density. Ground state molecular distortions are discussed as a possible cause of the effect.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 9466-9471 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The absolute cross sections for dissociative electron attachment to the molecules S2F10, S2OF10, and S2O2F10 were measured in an electron transmission experiment. The corresponding negative-ion fragments were identified in a separate mass spectrometric measurement. For S2F10, the attachment of thermal electrons (energy less than 0.1 eV) appears to result primarily in the formation of F− and SF5− with possibly a small fraction of SF4− and SF6−. The ions F− and SF5− are also produced from two attachment resonances at electron energies of about 4.5 and 9.5 eV. Both S2OF10 and S2O2F10 have unusually large dissociative attachment cross sections (on the order of 10−12 cm2) at energies near 0.1 eV. Electron attachment to S2OF10 yields primarily SOF5−, while S2O2F10 yields both SF5− and SOF5− with possible minor fractions of F− and SOF3−. Self-consistent-field calculations have been carried out on the neutral molecules and the corresponding anions to aid in the description of the observed dissociative attachment.
    Type of Medium: Electronic Resource
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