Flow-drift technique for ion mobility and ion-molecule reaction rate constant measurements. II. Positive ion reactions of N+, O+, and H2+ with O2 and O+ with N2 from thermal to [inverted lazy s]2 eV

Abstract

The positive ion-molecule reactionsN++O2→ NO++O→ O2++N,N2++O2→ O2++N2,O++O2→ O2++O,O++N2→ NO++N,were measured in a newly constructed flow-drift tube apparatus. Reactions (a), (b), and (c) were measured from thermal energy to approximately 2 eV ion kinetic energy in the center of mass. Reaction (d) was measured from 0.3–3 eV ion kinetic energy. The data agree well with previous thermal values at low energies and agree well with beam data at the highest energy. In the case of all the reaction except (a), there is an initial decrease of the rate constant with increasing energy followed by an increase.

A self-consistent estimate of O<sup>+</sup> + N<sub>2</sub> − rate coefficient and total EUV solar flux with λ < 1050 Å using EISCAT observations

“…The rate coe cient proposed by St.-Maurice and Torr (1978) widely used in aeronomic calculations provides the lowest values for this rate coe cient in the ionospheric temperature range. On the other hand the temperature dependence given by McFarland et al (1973) is very steep. It was e ciently used in our calculations to mimic the increase of this reaction rate due to vibrationally excited N 2 at high solar activity (Mikhailov and FoÈ rster, 1997;Mikhailov and Foster, 1997;Mikhailov and Schlegel, 1998).…”

“…Their rate coe cient is somewhat higher compared to St.-Maurice and Torr (1978) and McFarland et al (1973) values for temperatures <1000 K, but it steeply increases for T > 1300 K due to N Ã 2 (v 2). Nevertheless, the temperature dependence for the reaction rate by McFarland et al (1973) is even steeper for such temperatures. Therefore, it is interesting to have an independent estimate for this rate coe cient using an aeronomic approach.…”

“…It takes into account transport process for O + ( 4 S) and photochemical processes only for O + ( 2 D), O + ( 2 P), O 2 X 2 P , N + , N 2 and NO + ions in the 120±520 km height range. Three O + + N 2 ± reaction rate temperature dependencies (McFarland et al, 1973;St.-Maurice and Torr, 1978;Hierl et al, 1997) overlapping the range of laboratory measurements for this rate coe cient were used in our analysis. A two-component model of the solar EUV from was used to calculate the photoionization rates in 35 wavelength intervals (100±1050 A Ê ).…”

“…The amount of vibrationally excited N 2 molecules is negligible at T v 300 K, therefore this rate coe cient does not take into account the e ects of vibrational excitation. Similar¯ow-drift tube measurements but with argon bu er gas were provided by McFarland et al (1973). Di erent rate constants obtained by these two groups are attributed to di erent bu er gases used in their measurements.…”

Some new features of electron density irregularities over SHAR during strong spread F

“…At the time of this¯ight, the F layer was moving downward with a velocity of 20 ms )1 , which corresponds to westward electric ®eld of about 0.8 mV/m. The recombination coe cient, m R , has been taken from McFarland et al, (1973) and m in has been computed using the expression m in » 2.4´10 )11 M )1/2 n n , where n n is the neutral density and M is the mean molecular weight of the neutrals and ions (Kelley, 1989). These neutral parameters have been taken from the mass spectrometer incoherent scatter (MSIS-86) model.…”