Associative-detachment reactions

Viggiano A A and Paulson J F 1983 Temperature dependence of associative detachment reactions J. Chem. Phys. 79 2241-5... 

For the case of high temperatures found in the vicinity of hot stars, or in cloud regions under the influence of a shock wave, or in ionized nebulae, several authors have suggested (c.f. Jura, 1975, Dalgamo and McCray 1973) a gas phase formation scheme which could be a significant source for molecular hydrogen, Hj. The associative detachment reaction... 

The low effective value for the direct dissociative attachment process was later shown to be due, in part, to the regeneration of electrons via the associative detachment reaction,... 

Several exothermic associative detachment reactions do not occur at measurable rates (k < 10 12 cc./sec.), an example being... 

Associative detachment reactions are important in controlling the electron concentration in the earth s mesosphere [75]. Reactions in which more than one neutral product are formed also occur and are sometimes referred to as reactive detachment [76]. 

The above considerations are applicable to associative-detachment reactions in which no steric considerations apply. In certain reactions in which bonds must be broken while new bonds are formed, activation energies might be expected. In very exothermic reactions, e.g.. 

F. C. Fehsenfeld, E. E. Ferguson, and A. L. Schmeltekopf, Thermal-energy associative-detachment reactions of negative ions, /. Chem. Phys. 45, 1844-1845 (1966). 

Associative detachment reactions are unique to negative ions. The energy profiles for such reactions involve one or more curve-crossings between one or more of the attractive potential curves of the reactants and the potential curve for the product AB. AB is formed by the rapid autodetachment of an electron from (AB)- at short interaction distances. Exothermic associative detachment for atomic reagents is inevitably fast. Inhibiting factors can arise for molecular systems. 

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