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  • 1985-1989  (5)
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Material
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Collisions of excited alkali atoms with O2. I. Intermultiplet transfer (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 2084-2089 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The cross sections for the Rb(7S→5D), Rb(5D→7S), and Na(4D→5S) collisional transfers induced by O2 have been measured in absolute values as a function of the collision energy using a crossed beam apparatus. The experimental data have been compared with the predictions given by a multiple curve-crossing model where the symmetries of the states formed by the colliding alkali-metal atom–O2 system as well as the molecular orientation are considered. Good agreement is observed between experimental and calculated cross sections. This tends to show that in spite of its approximations, a multiple curve-crossing model would be useful to obtain fairly accurate informations about collisional processes involving alkali atoms with as much as 4 eV electronic excitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453183
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Near-resonant electronic-to-rotational energy transfer in Rb(7S→5D)–H2, D2 collisions at thermal energy (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 1451-1458 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The intermultiplet transfer Rb (7S→5D) induced by H2, D2, and He has been studied as a function of collision velocity using a crossed beam apparatus for which the initial rotational distribution of the molecular perturber was determined. A calibration using the blackbody induced redistribution of the excited states populations in the Rb beam allowed the absolute value of the cross section to be obtained. A situation where a near resonance exists (perturber H2) is compared with situations where near resonances do not occur (perturbers D2 and He). For low collision velocities (VR≤4000 m/s), the near-resonant process Rb(7S)+H2( j=1)→Rb(5D)+H2( j=3) has a much larger cross section than competing nonresonant processes (rotationally elastic or inelastic). Its cross section decreases with the relative velocity as ∼1/V2R. This behavior is compared with the predictions of two theoretical models (the impulse approximation model, which leads to a quantitative comparison with the measured velocity dependence, and the long range forces model). Above 4000 m/s the behavior of H2 closely resembles that of D2 and He where no near resonances exist. This suggests that for high velocities, the intermultiplet transfer is due to nonresonant processes only.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450489
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Collisions of excited alkali atoms with O2. III. Visualization of the collision path (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 6866-6872 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Inelastic scattering of electronically excited Na atoms by ground state O2 molecules was studied theoretically using a multiple-curve-crossing model. The movement of the collisional system within the potential grid describing the Na–O2 and Na+– O−2 pairs was visualized for two initial electronic states of Na (5S and 4D) at collision energies ranging between 0.2 and 1.0 eV. Visualization of the collision path was used to better understand prominent features of the redistribution of energy by collision within the system. Knowledge of the collision path for inelastic scattering also helped in discussing a competing reactive channel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457355
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Intermultiplet transfers of excited sodium atoms induced by nitrogen molecules (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 251-256 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The predictions of a multiple curve crossing model (MCC) were compared to experimental observations of various intermultiplet transfers in thermal energy Na/N2 collisions. This includes comparisons to the energy dependence and the absolute value of the Na(4D→5S) cross section that was measured in the experimental section of the present work using a crossed beam apparatus. This also includes comparisons with beam data available in the literature. These last experimental results are not always directly comparable to the calculated cross sections. Deconvolution or simulation procedures are then needed. The general agreement between the MCC calculations and the experimental results is good. In many cases it is much better than a factor 2. The cases or disagreement were discussed carefully, and each of them can be attributable to uncertainties in the experiment or in the procedures of deconvolutions and simulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455518
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Collisions of excited alkali atoms with O2. II. Reactive scattering (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 2398-2404 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Inelastic and reactive channels in excited Na atom/ O2 molecule collisions have been included into a single model based on multiple crossings between curves of the Na(n,l)–O2, Na+–O−2 (X 2Πg), and Na+–O−2 (A 2Πu) systems. Additionally, estimation is provided of the excited ion pair surface Na+–O−2 (A2Πu) in collinear geometry. This paper is essentially concerned with the reaction of Na(4D) giving NaO as product, a reaction where experimental results are available, but where no reaction mechanism has been proposed so far. When the reaction proceeds via the excited ion pair Na+ –O−2 (A 2Πu) , the calculations indicate that the cross section has a threshold collision energy and that impact parameters smaller than 1 A(ring) are involved. These features are consistent with the experimental data. This suggests that the excited ion pair Na+–O−2 (A2 Πu) is a likely intermediate in the reaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454023
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    Paper (German National Licenses)
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