Charge transfer reactions of ground O+(4S) and excited O+(2D) state ions with neutral molecules

Abstract

Total charge transfer cross sections have been measured for the reactions of 0.6 to 3.0 keV O+(4S) and O+(2D) ions with Ar, H2, N2, O2, CO, NO, and CO2. Time-of-flight techniques have been used to measure the fast neutral O products from charge transfer reactions in which reactant O+ ion beams have been produced by controlled electron impact ionization of oxygen. Reactions have been examined as a function of the electron energy used to produce the reactant ions and reaction cross sections determined for ground O+(4S) and excited O+(2D) state ions. The cross sections for charge transfer reactions involving the excited O+(2D) ions are significantly larger than the corresponding reactions of ground state ions in each of the above systems with the exception of CO2 where the revserse situation occurs due to small energy defects and favorable vibrational overlaps for reactions of O+(4S) ions.

Electron capture and loss by kilo-electron-volt oxygen atoms in collisions with He,H2,N2, andLindsay1, Yu2, McDonald3 et al. 2004Phys. Rev. A181140View full textAdd to dashboardCite

“…Perhaps chief among these is the potential influence of any excited O atoms that may be present in the projectile beam on the measurements. The effect of internal energy on O-atom electron-capture and -loss cross sections does not appear to have been studied previously, but it is well known that metastable oxygen ions often have significantly different electron-transfer cross sections from ground-state oxygen ions [10], and it is reasonable to suppose that the capture and loss cross sections studied here may depend upon the internal energy of the O atoms.…”

“…The energy defects for the reaction channels through which the atoms are produced are also extremely important, as it has been shown repeatedly that charge transfer is most likely to occur via reaction channels with small energy defects, and that channels with significant energy defects are often suppressed quite dramatically [10][11][12]; this effect is energy dependent and decreases as the kinetic energy increases. It is also worth noting that the influence of these various factors has only been established qualitatively, e.g., by Lindsay and Latimer [19].…”

“…It is also worth noting that the influence of these various factors has only been established qualitatively, e.g., by Lindsay and Latimer [19]. Here, CO 2 is utilized as the charge-transfer gas because reaction of either O + ͑ 4 S͒ ground-state or O + ͑ 2 D , 2 P͒ metastable ions, which are produced by the ion source in comparable numbers [11,20], is likely to result in the formation of O͑ 3 P͒ ground-state atoms due to the availability of near- resonant reaction channels with small energy defects [10,21]. Undoubtedly, some O͑ 1 D͒ and O͑ 1 S͒ metastable atoms will also be produced, but because the energy defects involved are greater than for formation of O͑ 3 P͒ atoms they will be formed in smaller numbers.…”

“…Significant fluxes of energetic oxygen ions and neutral atoms have been observed during geomagnetic storms [7], and the effect of these particle fluxes on the atmosphere is dependent on the magnitude of the various cross sections for collision with atmospheric neutral species and on the angular distribution of the scattered particles [8]. Cross sections for charge transfer of O + ions are already available [2,[9][10][11][12][13][14] and, together with the present measurements, repre-sent a comprehensive set of oxygen charge-changing data for use by atmospheric modelers.…”

Absolute Total Single–Electron–Capture Cross Sections of O2+ with N2 Gas

“…The absolute total cross section for single-electron-capture is then evaluated using the following In general, for these types of experiments, the absolute total cross section for electron capture may be determined in two ways; first, those experiments in which the cross sections are determined by measuring the fast neutral products, and utilized by us, Lindsay et al [3], and Moran et al [4]; and second, those experiments in which the slow ion products are measured, and implemented by, Flesch et al [25], and Li et al [26]. In fact, these two types of measurements lead to the same result.…”