Kinetics of oxygen species in an electrically driven singlet oxygen generator

Azyazov, Valeriy N.; Torbin, A. P.; Pershin, A. A.; Mikheyev, P. A.

doi:10.1016/j.chemphys.2015.09.007

Cited by 13 publications

(7 citation statements)

References 35 publications

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“…Non-thermal plasmas containing oxygen have been studied for many decades. They have numerous technological applications [1,2], such as plasma surface treatments and ozonizers [3][4][5], gas lasers [6][7][8][9][10][11], plasma assisted combustion [12][13][14][15], and (more recently) in biology and medicine [1,16,17]. Therefore, one might assume that all fundamental questions concerning oxygen plasmas have been resolved, and that the kinetic reaction scheme is well established, at least concerning the basic reactions that directly affect the state of the plasma [18][19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

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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“…Meanwhile, over the past few years, a great deal of effort has been devoted to experimental and theoretical studies of properties (including reactivity) of electronically excited molecules, since the parameters of molecules in the excited states are usually quite different from those in the ground states [15][16][17][18]. In this context, special interest was expressed in the electronically excited molecules of oxygen in the singlet a 1 Δ g and b g 1 S + states (excitation energy values T e are 0.98 and 1.64 eV, respectively [19]) owing to the importance of these states for atmospheric [20,21], combustion [22][23][24] and electric discharge [25][26][27] chemistry. Oxygen molecules in the singlet electronic states also participate in the physicochemical processes behind the strong shock waves in oxygen (air) [28,29] and in the active media of lasers [30].…”

Section: Introductionmentioning

confidence: 99%

Polarizability of electronically excited molecular oxygen: theory and experiment

Sharipov

Loukhovitski

Pelevkin

et al. 2019

J. Phys. B: At. Mol. Opt. Phys.

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Multireference ab initio calculations (by using the extended multiconfiguration quasi-degenerate second-order perturbation theory method XMCQDPT2) have been employed to determine the static polarizabilities for the ground triplet ( ) and two excited singlet (a1Δg and ) electronic states of molecular oxygen. The corrections to polarizabilities for the nuclear zero point motion are also reported. It was revealed that the excitation of an O2 molecule into the lowest singlet electronic states leads to a decrease in its polarizability: the polarizabilities of O2(a1Δg) and O2( ) are smaller (by factors of 0.967 and 0.962, respectively) than that of O2( ). The theoretical results for the state were quantitatively confirmed experimentally employing the diffraction at laser-induced gratings.

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“…This process has been observed in different oxygencontaining plasmas [19], [22], [23], [28], [29] and photolysis experiments [30]. In [8], [28], [31] the quenching of O 2 (a 1  g ) in a plasma afterglow was explained by reactions with vibrationally excited ozone molecules, which are produced by the initial stage in three-body recombination with O 2 [32]. In [3], [23], [33] the three-body recombination of O( 3 P) atoms with O 2 (a 1  g ) was invoked to explain the observed fast loss of O 2 (a 1  g ) at gas temperature T g < 700K.…”

Section: Introductionmentioning

confidence: 82%

“…It attracts attention due to their high chemical reactivity, due to high concentrations of active particles including oxygen atoms and electronically excited metastable molecules, notably singlet oxygen, O 2 (a 1  g ). These reactive species are essential in many technological plasma processes [1], [2], lasers [3]- [8] and combustion [9]- [13].…”

Section: Introductionmentioning

confidence: 99%

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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Kinetics of oxygen species in an electrically driven singlet oxygen generator

Cited by 13 publications

References 35 publications

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

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

Polarizability of electronically excited molecular oxygen: theory and experiment

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

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Kinetics of oxygen species in an electrically driven singlet oxygen generator

Cited by 13 publications

References 35 publications

Quenching of O2(b1Σg + ) by O(3P) atoms. Effect of gas temperature

Quenching of O2(b1Σg + ) by O(3P) atoms. Effect of gas temperature

Polarizability of electronically excited molecular oxygen: theory and experiment

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

Contact Info

Product

Resources

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

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

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