O2(b1Σg+) Quenching by O2, CO2, H2O, and N2 at Temperatures of 300–800 K

Загидуллин, М. В.; Khvatov, N A; Medvedkov, Ya. A.; Tolstov, G. I.; Mebel, Alexander M.; Azyazov, Valeriy N.

doi:10.1021/acs.jpca.7b07885

Cited by 13 publications

(2 citation statements)

References 36 publications

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“…It should be noted that the shock tube experiment of Borell et al [65] overestimates the rate constant at room temperature. Therefore, in this work, we used data from Zagidullin et al [66]. However, despite the increased gas temperatures observed in our experiments at higher pressures and currents, the rate of this is insignificant compared to the rates of surface loss of O 2 (b 1 Σ g + ).…”

Section: Reaction Schemementioning

confidence: 90%

Quenching of O₂(b¹Σ_g ⁺ ) by O(³P) atoms. Effect of gas temperature

Booth

Chatterjee

Guaitella

et al. 2022

Plasma Sources Sci. Technol.

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We present a detailed study of the density and kinetics of O2(b1Σg+) in steady-state and partially modulated DC positive column discharges in pure O2 for gas pressures of 0.3-10 Torr and 10-40 mA current. The time-resolved density of O2(b1Σg+) was determined by absolutely-calibrated optical emission spectroscopy (OES) of the A-band emission at 762 nm. Additionally, the O2(b1Σg+) density was determined by VUV absorption spectroscopy using the Fourier –Transform spectrometer at the DESIRS beamline at Synchrotron Soleil, allowing the absolute calibration of OES to be confirmed. The O(3P) atoms were detected by time-resolved sub-Doppler cavity ringdown spectroscopy (CRDS) using the O(3P2) -> O(1D2) transition at 630 nm. The CRDS measurements were synchronized to the discharge modulation allowing the O(3P) dynamics to be observed. As a function of gas pressure the O2(b1Σg+) density passes through a maximum at about 2 Torr. Below this maximum, the O2(b1Σg+) density increases with discharge current, whereas above this maximum it decreases with current. The gas temperature increases with pressure and current, from 300 to 800 K. These observations can only be explained by the existence of fast quenching process of O2(b1Σg+) by O(3P), with a rate that increases strongly with gas temperature, i.e. with a significant energy barrier. The data are interpreted using a 1D self-consistent model of the O2 discharge. The best fit of this model to all experimental data (including the O2(b1Σg+) average density as a function of pressure and current, the radial profiles, and the temporal response to current modulation) is achieved using a rate constant of kQ=10^-10∙exp(-3700/T) cm3/s.

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Section: Reaction Schemementioning

confidence: 90%

Quenching of O₂(b¹Σ_g ⁺ ) by O(³P) atoms. Effect of gas temperature

Booth

Chatterjee

Guaitella

et al. 2022

Plasma Sources Sci. Technol.

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“…This reaction is the reverse of the O 2 (b 1 Σ g + ) production process (R2) and its rate constant was obtained from [50] using the calculated thermodynamic equilibrium constant combined with the measured rate of the forward reaction (R2). In addition, the reaction (R4) was taken into account with the temperature dependence k (R4) (T ) = (7.4 ± 0.8) × 10 −17 T 0.5 exp((−1105.7 ± 53.3)/T) cm 3 s −1 (see table 2) in accordance with recent data of [51].…”

Section: Modelmentioning

confidence: 61%

Fast quenching of metastable O₂(a ¹Δ_g) and O₂(b ¹Σ_g ⁺) molecules by O(³P) atoms at high temperature

Volynets¹,

Lopaev²,

Рахимова³

et al. 2020

Plasma Sources Sci. Technol.

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Oxygen molecules in the lowest metastable state, O 2 (a 1  g ), play an important role in oxygen plasmas due to their high reactivity and significant concentrations. The accumulation of high densities of O 2 (a 1  g ) occurs due to its low quenching rate. This paper demonstrates the existence, at high gas temperatures (700-1700K), of fast quenching of O 2 (a 1  g ) by O( 3 P) atoms, a process that has not been considered in previous models. Experiments were carried out at oxygen pressures of 10-100Torr in an 81MHz CCP discharge in a quartz tube with external electrodes. This setup provides high absorbed power density, leading to both high gas temperatures and significant O( 3 P) densities. We observe that the O 2 (a 1  g ) density is significantly limited at high gas temperatures by rapid quenching by atomic oxygen . The results were interpreted using a self-consistent 1D discharge model. The observations can only be explained by the inclusion of a rapid quenching, with an activation energy in the range of 0.54-0.69eV. The rate constant was determined over a wide range of discharge conditions (P = 20-100 Torr and T g = 800-1700 K), giving values between 3•10 -11 ×exp(-8000/T) cm 3 /s to 1.5•10 -11 ×exp(-6300/T) cm 3 /s. A possible mechanism for this process is discussed. Measurements of the density of metastable O 2 (b 1  g + ) molecules also indicated the existence of quenching by atomic oxygen, with a somewhat lower activation energy of ~0.32 eV. The variations of the measured [O 2 (b 1  g + )]/N molefraction could be fitted by the model using a rate constant -210 -11 exp(-3700/T) cm 3 /s for this process. These quenching processes of metastable O 2 (a 1  g ) and O 2 (b 1  g + ) molecules by oxygen atoms are important for oxygen plasmas and could have a significant impact on the kinetics of oxygen-containing mixtures at higher gas temperatures, for example in plasma-assisted combustion or in high-pressure plasma processing reactors.

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