Reactive scattering of highly vibrationally excited oxygen molecules: Ozone formation?

Abstract

A new mechanism for the production of highly vibrationally excited OH in the mesosphere: An ab initio study of the reactions of O 2 ( A Σ u + 3 and A ′ Δ u 3 ) + H High level ab initio molecular orbital theory study of the structure, vibrational spectrum, stability, and low-lying excited states of HOONO A theoretical simulation of the 1s→2π excitation and deexcitation spectra of the NO molecule A new ab initio potential energy surface based on an internally contracted multireference configuration-interaction wave function is constructed for the O 2 (X 3 ⌺ g Ϫ ,)ϩO 2 (X 3 ⌺ g Ϫ ,ϭ0) →O 3 (X 1 A 1 )ϩO( 3 P) reaction with Ͼ20. The vibrational state-to-state reaction probabilities are calculated with a time independent reactive scattering method. The state selected reactive rate constants calculated with 2D reduced dimensionality theory are very small, suggesting that the reaction of ozone formation is not significant in the O 2 (X 3 ⌺ g Ϫ ,)ϩO 2 (X 3 ⌺ g Ϫ ,ϭ0) collision.

Nascent Vibrational Energy Distributions of O2(X3Σg−, v = 6−13) Generated in the Photolysis of O3 at 266 nm

“…Our results show that the monotonic decrease of vibrational populations with the vibrational quantum numbers over V ) 6-13. The results of the present study show a similar distributions measured by the kinetic analysis by Park and Slanger 15 and are in contrast to those obtained by measurements of the kinetic energies of the photofragment O( 3 P) by Geiser et al 16 (9) where k V M is the rate coefficient for vibrational relaxation of a level V by collisions with nonreactive relaxation partner M (M ) CF 4 or O 2 ) and k V diff is the first-order rate coefficient for diffusion loss of a level V. There have been reports that the vibrational relaxation of O 2 (6 e V e 15) by CF 4 and O 2 proceeds with single-quantum relaxation. 2,3,15,20,21,23,[33][34][35] The reported rate coefficients for relaxation of O 2 (X 3 Σ g -, V ) 11-21) by collisions with O 3 decrease from 5.5 × 10 -12 cm 3 molecule -1 s -1 for V ) 21 to 9 × 10 -14 cm 3 molecule -1 s -1 for V ) 11, 34 and the rate coefficients for V < 11 are expected to be smaller than those for V ) 11.…”

Reactivity and electronic states of O4 along minimum energy paths

“…Measurements of the total depletion rate of O 2 (v) show a sharp increase above vϭ25 which has not been fully explained either theoretically [10][11][12][13][14][15][16] or experimentally, 4,8 and recent spectroscopic studies 17 suggest the relevance of nonadiabatic processes in the system. Theoretical studies have concentrated on the importance of the ozone formation reaction ͑1͒ as a possible channel for O 2 (v) depletion, 11,13,15 enhancement of vibrational relaxation due to the saddle point region, 14 multiquantum vibrational relaxation, 16 and collision-induced dissociation processes.…”

Are Vibrationally Excited Molecules a Clue for the “O3 Deficit Problem” and “HOx Dilemma” in the Middle Atmosphere?

“…Unfortunately, experiment has failed to provide direct evidence showing that O 3 is formed, 39,40 with the caveat extending also to the available dynamics studies. [41][42][43][44][45][46][47][48][49] It should be noted that these theoretical dynamics studies employed either our own single-valued global potential energy surface 50 obtained from the DMBE (double many-body expansion 51-53 ) method for ground triplet O 4 or reduced-dimensionality single-valued ab initio surfaces, 41,47 and hence the relevance of nonadiabatic processes in explaining the above experimental results remains an open question. 22,49 However, dynamics studies 4,11 have shown that odd oxygen can be formed if the O x mechanism is reformulated to involve two vibrationally excited molecules, although this second-order process can occur only if two such species have a chance of colliding with each other.…”