Recombination of HCO+ and DCO+ ions with electrons

Role of the direct mechanism in dissociative recombination of HCO+and HOC+

“…Dissociative recombination of this ion has been studied extensively both experimentally and theoretically. The experimental studies [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] agree on a relatively large rate of 2 × 10 −7 cm 3 s −1 at room temperature. Recent measurements [21] of the cross section of DR of H 13 CO + found that the cross section at low collision energies falls off like E −1 and is followed by a structured high-energy peak centered around 10 eV.…”

The chemistry of protonated species in the martian ionosphere

“…3 from Korolov et al (2009) shows the various measurements and calculations in the low temperature range that had been reported in the literature up to the year 2009; it illustrates the problems associated with choosing the DR coefficient at low to thermal temperatures. The addition of studies of the last five years has apparently not alleviated the uncertainties involved.…”

“…At higher energies, the temperature dependence of the DR reaction is not as steep, and the branching ratio for channel (RC1c) becomes more important. The DR coefficient for HCO + at thermal energies has been measured by many researchers, and the results are generally in the range ð1 À 3Þ Â 10 À7 cm 3 s À1 , although there is a wide variation in the measured temperature dependence (e.g., Leu et al, 1973;Ganguli et al, 1988;Amano 1990;Gougousi et al 1997;Rowe et al, 1992;Smith and Spanȇl, 1993;Le Padellec et al, 1997;Laubé et al, 1998;Poterya et al, 2005;Korolov et al, 2009).…”

“…For low temperatures (T e 6300 K) we have adopted the temperature dependence ðT e Þ À1:25 (e.g., Korolov et al, 2009), while for temperatures between 300 and 4000 K, we have adopted a temperature dependence of ðT e Þ À1 .…”

“…The acronyms FALP (Flowing Afterglow/Langmuir Probe), and AISA (Advanced Integrated Stationary Afterglow) denote the experimental procedure. Reprinted from Korolov et al (2009), with kind permission of Elsevier. coefficient was 1:12 Â 10 À7 cm 3 s À1 at 120 K. The DR coefficients were slightly larger, $2 Â 10 À7 cm 3 s À1 for vibrational levels (v ¼ 1 À 3).…”