LAUSR

Monte Carlo simulation was used to study the translational relaxation of energetic O− ions produced by dissociative electron attachment to O2 molecules in oxygen plasmas in a strong electric field. Initial O− ions have rather high energies and are more reactive than the ions reaching equilibrium with the electric field. Therefore, there is a noticeable probability that the energetic O− ions participate in endothermic reactions prior to energy relaxation of these ions. The probabilities of charge exchange, electron detachment and ion impact vibrational excitation of O2 molecules were calculated versus the reduced electric field. It was shown that up to 6% of energetic O− ions produced in oxygen by dissociative electron attachment to O2 molecules are rapidly transformed to ions due to charge exchange collisions. The probability of electron detachment from energetic O− ions and the probability of vibrational excitation were smaller that the probability of charge exchange. Estimates showed that the increase in the effective rates of the ion–molecule reactions due to high reactivity of energetic O− ions can be important in oxygen plasmas for reduced electric fields of 50–100 Td.