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  • 1
    Electronic Resource
    Electronic Resource
    Statistical modeling of capture, association, and exit-channel dynamics in the CH3+/CH3CN system (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 1944-1956 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The ion–molecule reaction CH3++CH3CN is known to have an association channel leading to CH3CNCH3+ in competition with the exothermic binary channels H2CN++C2H4 and C2H5++HCN. This reaction has been modeled using a master equation treatment incorporating weak collisions. The parameters required for the Rice–Ramsberger–Kassel–Marcus (RRKM) treatment have been found from an ab initio investigation of the CH3+/CH3CN energy surface. A means of including capture rate coefficients in the RRKM approach is developed, in which only the hindered dipole rotation is coupled with the reaction coordinate at large separations. Existing experimental data from ion cyclotron resonance (ICR) spectroscopy and a selected ion flow tube are fitted by the model in the pressure range 10−7–0.3 Torr. The low pressure experimental results are accounted for by weak collisions of the complex with the bath gas (when M=He, 〈ΔEdown(approximately-greater-than) and 〈ΔRdown(approximately-greater-than)∼100 cm−1) corresponding to a collision efficiency β=0.05 for M=He and 0.14 for M=CH3CN. Unimolecular rate coefficients for the (CH3CNCH3+)* complex are calculated for all product channels at a range of temperatures from 300 to 600 K. The rate coefficient for radiative stabilization was found to be 225 s−1 at the conditions of the ICR experiment. The average lifetime of the complex was calculated to vary between 29 μs at 600 K to 0.47 ms at 300 K and the termolecular association rates from 3.4×10−24–9.8×10−23 cm6 s−1 (M=He) and from 6.7×10−23–2.2×10−21 cm6 s−1 (M=CH3CN) over the temperature range 600–300 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464228
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  • 2
    Electronic Resource
    Electronic Resource
    Interaction potentials and mobility calculations for the HeO+ system (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 5419-5424 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Valence bond, SCF, and MP4SDQ calculations are reported for three low lying states of the HeO+ molecular ion; 4Σ(4S), 2Π(2D), and 2Π(2P). Together with the two-temperature theory of ion transport, these interaction potentials have been used to calculate the drift velocity and reduced mobility of O+ in helium as a function of the electric field to gas number density ratio. The calculated HeO+(4Σ) interaction potentials adequately describe the mobility of ground state O+ in helium, however, the O+(2D) mobility calculated using the 2Π(2D) interaction potential does not match the experimental mobility measurements for the metastable O+* ion which have been reported as the O+(2D) state. An interaction potential is reported for HeO+[2Π(2P)] which will reproduce the experimental mobility of O+*.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453661
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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