Formation of MO Metal Atom Reactions with O2 and RO

In contrast with the diatomic halogens, reactions of metals with O2 and other oxidants frequently involve long-lived complexes. The MO2 or MOR lifetime may be close to a rotational period and the energy disposal may depend upon collision energy and the properties of the different metal atom. Chemiluminescence accompanies many of the metal atom oxidation reactions however, the branching fraction normally is small and the chemiluminescence aspect will not be emphasized here. Velocity distributions, from molecular-beam studies, and vibrational rotational distributions, from laser-induced fluorescence studies, are available and some of the results are summarized in Table 2.16. 

The Ba -h O2 reaction gives approximately symmetric forward-backward reactive scattering for Et = 2.2 kcal mole and must proceed via a long-lived complex (also see references mentioned in ref. 28b). Rough vibrational and rotational BaO distributions were obtained by laser fluorescence. Quantitative assignments of populations were thwarted by formation of high J levels, rotational perturbations in the upper state, and lack of detailed 

S) with 802 For CO2 the yields of CaOCX H ) and the spin allowed product, CaO( n), are comparable. For SO2, energetic constraints require the following products, which involve change of spin  

Disregarding the known complications associated with the variation of the chemiluminescence intensity with pressure, the Ba -h N2O reaction would seem the more straightforward from consideration of the number of potential surfaces. A careful molecular-beam study has demonstrated that this reaction = 98 kcal mole actually is direct, rather than proceeding via a complex, with BaO mainly being scattered in the backward hemisphere 

A molecular-beam study indicates that an osculating or long-lived intermediate is involved in the Sn + O2 reaction. Comparison of the translational energy disposal to statistical theories was impossible because of the participation of the three Sn low-energy atomic states. A Sn Og complex is the expected intermediate state. 

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