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  • 11
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 93 (1989), S. 7535-7536 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 94 (1990), S. 8567-8573 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 967-978 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Rotationally resolved fluorescence excitation and resonance enhanced multiphoton ionization (MPI) spectra of the 610130 one-photon band of benzene at the onset of "channel three'' are reported. The fluorescence decay is monitored after rotationally selected excitation and a large variation of the nonradiative decay time (〈1 to 6.8 ns) is found for the different rotational states at the vibrational excess energy of 3287 cm−1 in S1. The rotational structure of the fluorescence excitation spectrum and the MPI spectrum measured with delayed laser pulses differ considerably. All observed lines of the MPI spectrum were assigned and the rotational line structure can only be understood with a model which incorporates interference between different decay channels. Due to this interference, particular rotational states decay fairly slowly and give rise to lines in the spectrum while states with neighboring rotational quantum numbers decay rapidly and are therefore not found in the spectrum. The previously reported drastic increase of the electronic, nonradiative decay of benzene in this region of excess energy, which led to the postulation of "channel three,'' cannot be confirmed. Instead, the optically excited rovibronic states are thought to be coupled to background states within S1 which are themselves broadened due to strong coupling to the highly excited S0 electronic state rather than due to an unknown ("channel three'') or isomerization process.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 95 (1991), S. 391-394 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The potential energy surface (PES) of the benzene⋅⋅⋅Ar complex was investigated ab initio using the second-order Moller–Plesset theory demonstrating the practical use of such calculations for these complexes. Among five structures studied, the highest symmetry C6v structure for the Ar appeared to be most stable (stabilization energy: 429 cm−1; distance of molecular centers: 3.526 A(ring)). The PES is much more isotropic than was found in previous papers using an empirical potential. The calculated intermolecular distance is in excellent agreement with recent high resolution measurements—also the dipole moment is in excellent agreement with known data.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 5893-5897 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The structure of the benzene dimer has aroused considerable interest due to recent experimental measurements and hence extensive theoretical calculation is topical. Nine structures of the benzene dimer were investigated using the second-order Møller–Plesset theory. The calculations were performed with smaller (MIDI-1+s+p) and larger (6-31+G*) basis sets. The T-shape structure was found to be the most stable but with a very shallow minimum; the wagging motion around the lowest hydrogen in the range of ±10° is practically nonhindered. These results together are consistent with the structure found experimentally. The final binding energy for the T structure (distance of molecular centers equal to 5.0 A) is −2.7±0.4 kcal/mol, which is more than the value derived from experiments. The calculated dipole moment is in excellent agreement with experiment.
    Type of Medium: Electronic Resource
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  • 16
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The C6v structure of benzene⋅⋅⋅X (X=He, Ne, Ar, Kr, Xe) complexes was investigated with second-order Møller–Plesset (MP2) theory; for the benzene⋅⋅⋅He the whole potential-energy surface (PES) was also studied. The stabilization energy of the benzene⋅⋅⋅He was also determined at the fourth-order Møller–Plesset (MP4) level; the respective MP4 stabilization energy is almost identical with MP2 stabilization energy which is due to the compensation of MP3 and MP4 contributions. The ab initio MP2 intermolecular distances agree nicely for all the complexes studied with the experimental value. While the stabilization energy of benzene⋅⋅⋅He and benzene⋅⋅⋅Ne (67 cm−1; 99 cm−1) is considerably smaller than that of benzene⋅⋅⋅Ar (429 cm−1), the intersystem distance differs less (3.32 A(ring), 3.50 A(ring), 3.53 A(ring)). The stabilization energies and intersystem distances for benzene⋅⋅⋅Kr and benzene⋅⋅⋅Xe are 485 and 601 cm−1 and 3.71 and 3.89 A(ring), respectively. The PES of benzene⋅⋅⋅He differs from that of benzene⋅⋅⋅Ar and can be characterized as more isotropic. The harmonic and anharmonic stretching frequencies were determined for all the complexes; anharmonicity plays a crucial role only for the benzene⋅⋅⋅He complex. Theoretical and experimental stretching frequencies for benzene⋅⋅⋅Ar and benzene⋅⋅⋅Kr agree very well.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 1914-1922 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We present a new ion spectroscopic technique by which it is possible to investigate larger molecular ions by scanning an entire electronic state and coincidentally measuring and, hence, fixing the mass of the fragment ion observed. The technique involves primary resonance excitation together with secondary absorption followed by dissociation as detection process, employing the absorption of two photons in the ion. This method accesses the nondissociating vibronic levels of an electronic state rather than just the narrow range of predissociating levels, as in one-photon dissociation spectroscopy. Spectra of CH3I+ and CD3I+ over a range of 7000 cm−1, beginning at the origin of the A˜ state, were recorded with progression bands up to n=21. These spectra allow for the first time an unambiguous assignment of the A˜←X˜ transition of CH3I+ and CD3I+. The exact positions of the electronic origin as well as of the origin of several progressions and new values for several vibrational constants of methyl iodide cations are reported. Some 300 bands in both ions were measured and assigned with this technique.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 1299-1306 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Isotopically mixed jets of benzene produced important new detailed structural results from the various possible isotopic benzene trimers in a supersonic jet. From different isotopic spectral shifts, a detailed and consistent model of the interaction between the three benzene molecules can be inferred. The splitting of the 0–0 transition of isotopically mixed trimers can be predicted from this model. This model is consistent with a "zig–zag'' structure for the trimer, not a cyclic structure. In contrast to the dimer spectra, van der Waals modes were observed. We also discovered an important, new exciton splitting in the van der Waals modes. This splitting demonstrates for the first time that the van der Waals modes are uncoupled from molecular vibrations. Furthermore, it is a sensitive indicator of the identity of the molecules so coupled. The spectra of higher benzene clusters (dimer to pentamer) have also been measured.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 2809-2811 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The potential energy surfaces of fluorobenzene...Ar and p-difluorobenzene...Ar were studied by ab initio calculations with inclusion of second-order Møller–Plesset correlation energy. The optimal structures of both complexes agree nicely with experimental data. The theoretical stabilization enthalpy for the second complex (294 cm−1) agrees well with the experimental data (190–242 cm−1). The fluorine substitution of the benzene molecule does not influence the characteristics of the respective complex. The dipole moment of both complexes was calculated; in both cases the electron transfer from fluorobenzene to Ar was found.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 6223-6226 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The potential energy surface of the benzene...N2 was investigated ab initio using second-order Møller–Plesset (MP2) theory. The calculations were performed with 6-31+G*/[5s4p2d] and 6-31+G*/[5s4p3d] basis sets. Among five structures studied the sandwich structure (N2 lies in the plane parallel to the benzene ring) appeared to be most stable. The calculated intermolecular distance (3.46 A(ring) after vibrational averaging) is in excellent agreement with recent high resolution measurements. Calculated stabilization energy (591 cm−1) and intermolecular vibrational frequencies (stretching, 57 cm−1; torsion, 73 cm−1) are compared with available experimental results.
    Type of Medium: Electronic Resource
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