Electron detachment from O⁻₂ions in oxygen: the effect of vibrational excitation and the effect of electric field

Abstract

Electron detachment from O − 2 ions has been theoretically studied in oxygen (i) when the gas is vibrationally excited and (ii) when the ions are heated in a strong external electric field. Assuming that electron detachment proceeds via the formation of vibrationally excited temporary O − 2 ions, the detachment rate was determined on the basis of the statistical approach for the vibrational transfer and relaxation in collisions between O − 2 ions and O 2 molecules. The approach used in our previous work to study electron detachment in vibrationally excited oxygen was amended to take into account the conservation of total angular momentum in O − 2 -O 2 collisions. The calculated detachment rates agree well with available measurements in oxygen under equilibrium conditions. The method was used to calculate detachment rates under strongly non-equilibrium conditions in which the vibrational temperature of molecules or ion translational temperature is elevated. The obtained results were compared with available measurements in drift tubes.

Guided ionization waves: The physics of repeatability

“…Figure 23 compares the detachment rate constant from simulations and experimental measurements in oxygen gas at T ¼ 300 K. There is a good agreement between the simulation, 202 semi-empirical calculation, 203 and experiment. 204 However, the difference between the calculations and the measurements (curve 4) is very large, up to two orders of magnitude.…”

“…So, the seed electrons could be produced by detachment. The formation of O 2 À is described by the attachment pathways 201,202…”

“…. The detachment rate constant as a function of reduced electric field in oxygen at T ¼ 300 K. Curve 1 represents the results of numerical simulations, curve 2 corresponds to a semi-empirical calculation, and curves 3 and 4 show the results of experimental measurements 202. Reproduced with permission from N. Aleksandrov and E. Anokhin, J. Phys.…”

Corrigendum: Experimentally derived rate coefficients for electron ionization, attachment and detachment as well as ion conversion in pure O2 and N2–O2 mixtures (2018 J. Phys. D: Appl. Phys. 51 355201)

“…The measurement in different gas mixtures in figure 8b shows that the rate is smallest for pure oxygen, and increases with increasing nitrogen content. The reference values from Moruzzi [54] [8,53,55,56,57,17]. The measurement of Frommhold [53] was referenced in fig.…”

Numerical simulation of back discharge: Influence of pinhole geometry on the regime transitions

“…[17]. The detachment process [26,27], as well as photoionization [26,28], are simulated by assuming an initial background of electrons of n e ¼ 10 10 cm À3 at the pinhole region to ensure the possible propagation of a positive streamer.…”