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  • 1
    Electronic Resource
    Electronic Resource
    Chemiluminescent reactions of electronically excited alkaline earth atoms. II. Energy dependence in Ba*+O2→BaO*+O (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 4913-4920 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The reaction of Ba(6s 6p1P1) with O2 has been investigated in a crossed beam experiment as a function of the collision energy. The electronically excited product BaO is not statistically populated and the difference from statistics increases with the collision energy. Such a result is markedly in contrast with what was observed in the reactions of Ba(6s21S0) and Ba(6s5d1D2) with O2 where the existence of a long-lived complex results in a statistical distribution of internal energy of the BaO product. The present result is interpreted as due to the collisional system following a different channel involving excited electronic states of the intermediate, BaO2 above the ionization limit, instead of the strongly bound states of barium peroxide which are involved in reactions of less excited Ba states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460576
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  • 2
    Electronic Resource
    Electronic Resource
    Chemiluminescent reactions of electronically excited alkaline-earth atoms. I. Energy dependence in Ba(6s6p1P1)+CO2→BaO(A,A')+CO (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 7050-7054 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The visible chemiluminescence from the reaction between a barium atom excited in the 6s6p1P1 resonance state and a CO2 molecule has been studied as a function of the collision energy. The emission originates from a BaO molecule excited in the A 1∑+ and A' 1Π levels. The population ratio of the electronic A and A' states appears to be statistical. The internal energy of the electronically excited BaO product is also statistically distributed at low collision energy (0.12 eV) and starts to deviate from statistics when the collision energy is increased, the mean internal energy of BaO remaining almost constant. The cross sections for chemiluminescence are of the order of a few A(ring)2 and depend only weakly of the collision energy. The reaction of Ba (1P) with CO2 to form BaO (A or A') is interpreted as a direct reaction without a barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456232
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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Energy dependence of the inelastic process Ba(6s6p1P1)+Ar,He→Ba(6s6p3P1,2)+Ar,He (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 5354-5355 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The cross section of the inelastic transfer from Ba(6s6p 1P1) to Ba(6s6p 3P1,2) induced by collision with argon or helium is measured as a function of the collision energy. The existence of a 0.15 eV energy barrier in the formation of Ba(6s6p 3P1) is observed and allows to explain why Ba(6s6p 3P2) was the only product formed in a previous cell experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459657
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  • 5
    Electronic Resource
    Electronic Resource
    Reaction of barium atoms with N2O clusters (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 3081-3085 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The chemiluminescence of the reaction of barium atoms and N2O molecules is observed in a crossed molecular beam experiment. The conditions of the molecular N2O beam are varied so that this beam contains no, or many large, N2O clusters. No additional chemiluminescence occurs when the cluster concentration is increased. The large difference in electronic structure between monomers and polymers, which has been shown by Echt et al. by measurement of electron attachment, suggests that a different reaction channel yielding BaO solvated in a N2O cluster is responsible for this absence of chemiluminescence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453951
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  • 6
    Electronic Resource
    Electronic Resource
    The dynamics of electronic to vibrational, rotational, and translational energy transfer in collision of Ba(1P1) with diatomic molecules (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 4094-4103 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Doppler measurements taken over a range of probe-laser angles in a crossed-beam experiment were used, in conjunction with forward convolution analysis, to obtain flux–velocity contour maps for Ba(3P2) produced in a collision of Ba(1P1) with H2, N2, O2, and NO. The contour maps suggest a general model for the dynamics of this process in which large impact parameter collisions result in a near-resonant transfer of initial electronic energy into final vibrational energy, while close collisions produce sideways scattering and effectively couple electronic energy to translation. The molecular collision partners fall into two categories: for one group, comprising O2 and NO, the existence of a well-defined molecular anion with favorable Franck–Condon factors linking excited vibrational levels to the ground vibrational state of the neutral results in greatly enhanced coupling for the near-resonant process. Molecules for which there exist no stable anions, such as N2 and H2, represent a second category. The electronically inelastic collision for this group is instead dominated by the nonresonant process yielding the ground vibrational state and large translational energy release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.463914
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Collision energy dependence of the chemiluminescent reaction: Ba+N2O→BaO+N2 (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 1945-1949 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The chemiluminescence spectrum of the reaction Ba+N2O→BaO+N2 has been studied using a crossed beam apparatus as a function of the collision energy over the range 0.1–0.6 eV. The relative importance of its red wing increases as the collision energy is raised. Moreover, the cross section associated to chemiluminescence at a wavelength λ of the range 450–700 nm goes through a maximum as the collision energy is varied, the position of which depends significantly on the value of λ. The importance of this effect cast some doubt about works, where the energy dependence of the "total'' chemiluminescence is measured using a detector which does not have a constant response over the wide range of the chemiluminescence. The analysis of the present results reveals that increasing the collision energy results in lowering the average vibrational excitation present in the emitting states A 1Σ+ and A' 1Π of the product BaO.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455092
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  • 9
    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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  • 10
    Electronic Resource
    Electronic Resource
    Reaction between Ba and N2O in large Arn clusters (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 99 (1993), S. 8705-8712 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The collision between a Ba atom and an Arn cluster carrying N2O molecules has been investigated under crossed molecular beam conditions. The argon cluster acts as a solvent for the Ba+N2O reaction, which is monitored through its chemiluminescent channel forming electronically excited BaO. The effects of cluster size and the number of N2O molecules per cluster have been investigated systematically as have the effects of extra molecules present upon the cluster (CH4). It has been shown that (i) the BaO reaction product either stays solvated in the cluster or is lost from the cluster; (ii) the reaction probability between Ba and N2O is approximately unity for the clusters considered here; (iii) the chemiluminescence quantum yield decreases as the number of N2O molecules per cluster is increased. The effect of a thermal bath (the argon cluster) on the dynamics of the well studied gas phase reaction Ba+N2O is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.465594
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