Non Equilibrium Vibrational Population and Dissociation Rates of Oxygen in Electrical Discharges: The Role of Atoms and of the Recombination Process

The influence of oxygen atoms on the population densities of vibrational levels of molecular oxygen has been studied for discharge conditions in which the atoms come 1) from electronic transitions to Herzberg and Schumann systems 2) from the pure vibrational mechanism (PVM) discussed in Chem. Phys. 30 (1978) 95. In the first case the atoms deactivate the first vibrational levels of O 2 , thus reducing the vibrational temperature and the propagation of the introduced vibrational quanta by V — V exchanges. Under these conditions PVM disappears. An assisted recombination dissociation mechanism, however, holds in these conditions, due to the recombination process which induces a strong disequilibrium on the levels near to the dissociation continuum. These levels can redissociate by collisions with heavy particles. The results of pure vibrational mechanism in the presence of atoms are very similar to those discussed in our previous work. The production of oxygen atoms self adjusts to small values due to the increased importance of V — T deactivation by oxygen atoms.