Collisional removal of O2 (c 1Σ−u, ν=9) by O2, N2, and He

Abstract

The collisional removal of O 2 molecules in selected vibrational levels of the c 1 ⌺ u Ϫ state is studied using a two-laser double-resonance technique. The output of the first laser excites the O 2 to ϭ9 or 10 of the c 1 ⌺ u Ϫ state, and the ultraviolet output of the second laser monitors specific rovibrational levels via resonance-enhanced ionization. The temporal evolution of the c 1 ⌺ u Ϫ state vibrational level is observed by scanning the time delay between the two pulsed lasers. Collisional removal rate constants for c 1 ⌺ u Ϫ , ϭ9 colliding with O 2 , N 2 , and He are ͑5.2Ϯ0.6͒ϫ10 Ϫ12 , ͑3.2Ϯ0.4͒ϫ10 Ϫ12 , and ͑7.5Ϯ0.9͒ϫ10 Ϫ12 cm 3 s Ϫ1 , respectively. As the rate constants for O 2 and N 2 are similar in magnitude, N 2 collisions dominate the removal rate in the earth's atmosphere. For ϭ10 colliding with O 2 , we find a removal rate constant that is 2-5 times that for ϭ9 and that single quantum collision cascade is an important pathway for removal.

Electronic kinetics of molecular nitrogen and molecular oxygen in high-latitude lower thermosphere and mesosphere

“…By the way, Copeland et al (1994) and Slanger et al (1984) have obtained lowest limits for the coefficients of v=8 and 10 (Pejacovic et al, 2007, Table 2). We have not found good agreement of the calculated coefficients for the c 1 − u state with experimental data by Copeland et al (1996) and Wouters et al (2002). But in any case both experimental and calculated values show some oscillations in the region of v ≥ 8.…”

“…It is seen that intramolecular processes dominate in the quenching of the c 1 − u (v ≥ 3), A 3 u (v ≥ 2), A 3 + u states. Since electron energy of the A 3 + u state of N 2 (∼6.2 eV) is much greater than the energies of highest vibrational levels of Herzberg states of O 2 (∼5.1 eV), so we believe that intramolecular electron energy transfer processes Copeland et al (1996) and Wouters et al (2002) (triangles at T =300 K, crosses at T =245 K). Dashed line and dash and three dotted line are the contributions of intramolecular and intermolecular electron energy transfer processes, respectively.…”

“…As for N 2 molecule we suggest to consider the rate of an intramolecular process independent on the kind of the colliders O 2 or N 2 . Actually experimental results by and Copeland et al (1996) shown in Figs. 1, 2, 4, 5 have indicated that the quenching rates on N 2 molecules are somewhat smaller, but the difference is not so important in our consideration of the kinetics of electronically excited O 2 .…”

“…dominate in the quenching of Herzberg states by molecular nitrogen. The sums of the contributions of intramolecular processes for the A 3 + u and c 1 − u states are compared with experimental data of Knutsen et al (1994) and Copeland et al (1996) 5, respectively. Better agreement of our results with experimental data could be received in the case of a normalising of calculated values by factors 0.6 for the A 3 + u state and 0.8 for the c 1 − u state.…”

Nightglow vibrational distributions in the A<sup>3</sup>Σ<sub>u</sub><sup>+</sup> and A'<sup>3</sup>Δ<sub>u</sub> states of O<sub>2</sub> derived from astronomical sky spectra

“…In particular, there has been considerable work carried out in recent years on determining the loss rate coefficients of the various O 2 electronic states as a function of vibrational level (Copeland et al, 1996;Hwang et al, 1998;Kalogerakis et al, 1999Kalogerakis et al, , 2002Knutsen et al, 1994;Slanger and Copeland, 2003). When combined with the atmospheric vibrational distributions, it will ultimately be possible to characterize the production rates of O 2 vibronic levels, leading to a detailed picture of recombination dynamics.…”