Collisional relaxation of O2($X^3\Sigma _g^ -$X3Σg−, υ = 1) and O2(a1Δg, υ = 1) by atmospherically relevant species

Abstract

Laboratory measurements are reported of the rate coefficient for collisional removal of O(2)(X(3)Σ(g)(-), υ = 1) by O((3)P), and the rate coefficients for removal of O(2)(a(1)Δ(g), υ = 1) by O(2), CO(2), and O((3)P). A two-laser method is employed, in which the pulsed output of the first laser at 285 nm photolyzes ozone to produce oxygen atoms and O(2)(a(1)Δ(g), υ = 1), and the output of the second laser detects O(2)(a(1)Δ(g), υ = 1) via resonance-enhanced multiphoton ionization. The kinetics of O(2)(X(3)Σ(g)(-), υ = 1) + O((3)P) relaxation is inferred from the temporal evolution of O(2)(a(1)Δ(g), υ = 1), an approach enabled by the rapid collision-induced equilibration of the O(2)(X(3)Σ(g)(-), υ = 1) and O(2)(a(1)Δ(g), υ = 1) populations in the system. The measured O(2)(X(3)Σ(g)(-), υ = 1) + O((3)P) rate coefficient is (2.9 ± 0.6) × 10(-12) cm(3) s(-1) at 295 K and (3.4 ± 0.6) × 10(-12) cm(3) s(-1) at 240 K. These values are consistent with the previously reported result of (3.2 ± 1.0) × 10(-12) cm(3) s(-1), which was obtained at 315 K using a different experimental approach [K. S. Kalogerakis, R. A. Copeland, and T. G. Slanger, J. Chem. Phys. 123, 194303 (2005)]. For removal of O(2)(a(1)Δ(g), υ = 1) by O((3)P), the upper limits for the rate coefficient are 4 × 10(-13) cm(3) s(-1) at 295 K and 6 × 10(-13) cm(3) s(-1) at 240 K. The rate coefficient for removal of O(2)(a(1)Δ(g), υ = 1) by O(2) is (5.6 ± 0.6) × 10(-11) cm(3) s(-1) at 295 K and (5.9 ± 0.5) × 10(-11) cm(3) s(-1) at 240 K. The O(2)(a(1)Δ(g), υ = 1) + CO(2) rate coefficient is (1.5 ± 0.2) × 10(-14) cm(3) s(-1) at 295 K and (1.2 ± 0.1) × 10(-14) cm(3) s(-1) at 240 K. The implications of the measured rate coefficients for modeling of atmospheric emissions are discussed.

Investigation of oxygen vibrational relaxation by quasi-classical trajectory method

“…Relaxation times, calculated by Eq. (11) using the data from [14,23] are nearly twice larger than the present results, however this range of temperatures is not of interest for hypersonic simulations. Present relaxation time, obtain by Eq.…”

“…The experimental measurements by [23,14] suggest twice lower rates of vibrational deactivation, however this disagreement is applied only to room temperature that is not the focus of the present study. The results of [12] are clearly lower than the other data sets.…”

“…All papers can be divided into two categories depending on the reported temperature range. The first category presents data at atmospheric conditions [14,23]. Relaxation of molecular oxygen is observed through ozone photolysis by laser radiation.…”

Singlet Molecular Oxygen Formation by O-Atom Recombination on Fused-Quartz Surfaces

“…The relaxation of vibrationally hot O 2 a 1 Δ g in an environment that contains both O atoms and vibrationally hot (up to υ 20) ground-state O 2 is very complex [30]. There is rapid dynamic equilibration between the υ 1 levels of O 2 a 1 Δ g and ground-state O 2 , thought to be driven by very efficient electronic-to-electronic energy exchange between a 1 Δ g and ground-state oxygen molecules [30]. In our test environment, we expect O atoms to be the dominant vibrationtranslation (V-T) collision partner relaxing the υ 1 populations to υ 0 in both O 2 species.…”

Kinetics of oxygen species in an electrically driven singlet oxygen generator

“…as phase processes involving the reactive oxygen species O 2 (a 1 ∆), O( 3 P) and O 3 have been studied extensively due to their importance in the terrestrial atmosphere [1][2][3][4][5][6], oxygencontaining plasmas [7][8][9][10], the oxygen-iodine laser [11][12][13][14] and combustion [15][16]. There has been a long standing interest in the possibility of developing a discharge driven oxygen iodine laser (DOIL), where O 2 (a 1 ∆) is produced via electric discharge [7][8][9][10][11][12][13].…”