Low-energy electron attachment and detachment in vibrationally excited oxygen

Abstract

Three-body electron attachment to O2 molecules and electron detachment from ions have been theoretically studied in vibrationally excited oxygen and O2-containing mixtures. Assuming that electron attachment and detachment proceed via the formation of vibrationally excited temporary ions, the rates of these processes were determined on the basis of the statistical approach for the vibrational transfer and relaxation in collisions between ions and O2 molecules. The calculated attachment and detachment rate constants turned out to agree well with available measurements in unexcited oxygen. This method was extended to calculate attachment and detachment rates in vibrationally excited oxygen. It was shown that the effect of vibrational excitation on electron detachment is profound, whereas attachment of low-energy electrons to vibrationally excited O2 is inefficient. The calculated vibrational distribution of stable ions turned out to be non-equilibrium in an excited gas and the effective vibrational temperature of the ions was much lower than the vibrational temperature of molecules. An analytical method was suggested to determine this distribution and the effective vibrational temperature. The calculated rate constants were used to simulate the formation and decay of an electron-beam-generated plasma in N2 : O2 mixtures at elevated vibrational temperatures. The calculations showed that vibrational excitation of molecules leads to orders of magnitude increase in the plasma density and in the plasma lifetime, in agreement with available observations.

Carbon monoxide dissociative attachment and resonant dissociation by electron-impact

“…Since dissociation is an important process in plasma kinetics, as it leads to the depopulation of the vibrational levels, in the present letter we wish to extend our previous work to dissociative electron attachment (DEA) and to resonant electron impact-dissociation (EID) of CO, taking place through the temporary formation of the resonance ( ) Π − CO X 2 . DEA is known to be a relevant process that produces stable negative ions of oxygen [9]. The reactions considered here, respectively for DEA and EID processes, are the following:…”

Chemical composition of plasma of dielectric barrier discharge at atmospheric pressure with a liquid electrode

“…5 and 6. As for the plasma discharge in О 2 [48], the main process of formation is the three body reaction (72), but the process of destruction is reaction (51) for the interaction of О 3 with radicals OH, rather than reaction (20). The frequency of О 3 termination in the last reaction is weakly dependent on the concentration of Н 2 О due to the weak depen dence of the concentration of OH on the Н 2 О content (Fig.…”

“…The rate con stants of attachment processes increase by orders of magnitude with the effective vibrational temperature [20]. The calculation of the distributions of О 2 and Н 2 О molecules over vibrational levels, performed in the same manner as in [18], showed that the effective vibrational temperature did not exceed 330 K, since the electron impact excitation frequency was much lower than the V-T exchange frequency.…”

The electric field inside an air bubble on hydrodynamic luminescence

“…Adherence is not significant in this case-the case of high vibrational temperatures-as is it completely compensated by the reverse process [10,11].…”