Three body attachment rate

Table 1 Three-Body Attachment Rate Constants /cm for the Reaction e Room Temperature (From Refs. 10 and 11.)...

Three-body attaehment Rate coefficient Three-body attachment Rate coefficient... 

The work of Bleekrode and Nieuwpoort (3) suggests that at 1 torr in a stoichiometric C2H2/02 flame, tic2 1013 cm.-3 The observed rate of production of negative ions would thus necessitate a three-body rate constant for attachment of electrons to C2 of about 5 X 10-28 cm.6 molecule-2 sec.-1 This seems somewhat high but is not altogether impossible. 

Figure 3 The temperature dependence of the three-body rate constant of O2. (From Ref. 58.) The broken curve shows the temperature dependence of the rate constant calculated from Herzenberg s theory. The solid curve shows a calculated rate constant, which involves both the contributions from the broken curve and the rate constant due to electron attachment to van der Waals molecule (02)2-...

The three-body electron attachment can be a principal channel for electron losses when electron energies are not high enough for the dissociative attachment, and when pressure is elevated (usually more than 0.1 atm) and the third-order kinetic processes are preferable. In contrast to the dissociative attachment, the three-body process is exothermic and its rate coefficient does not depend strongly on electron temperature. Electrons are usually kinetically less effective as a third body B because of a low degree of ionization. 

Figure 2-10. Rate coeificients of electron attachment to different molecules in three-body collisions as a function of electron temperature molecular gas is assumed to be at room temperature.

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