A model for temperature-dependent collisional quenching of OHA2∑+

Paul, Phillip H.

doi:10.1016/0022-4073(94)90150-3

Cited by 138 publications

(49 citation statements)

References 42 publications

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“…N OH (t) can be considered as a constant during the laser pulse due to fast RET with rate constant about 3.5 Â 10 À9 s À1 or higher. 18,20 The same approximation has been used by others 5,8 and gives very good agreement with experiment. The spectrally and temporally integrated fluorescence can be written as…”

Section: -6supporting

confidence: 58%

“…while at low water contents the quenching of OH(A) by N 2 and O 2 (appearing in the discharge zone due to backdiffusion of air) plays an important role 18 OHðAÞ…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, the decay time corresponding to radiative depopulation of OH A 2 R þ to ground state is reported to be about 0.685 Â 10 À6 s. 17 Thus, the observed much shorter value is likely determined by the collisional quenching of OH with H 2 O, whereas the quenching by Ar is much weaker. Paul 18 postulated that quenching occurs via an ion-pair intermediate…”

Section: -4mentioning

confidence: 99%

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OH radicals distribution in an Ar-H2O atmospheric plasma jet

Nikiforov

Xiong

et al. 2013

Physics of Plasmas

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Recently, plasma jet systems found numerous applications in the field of biomedicine and treatment of temperature-sensitive materials. OH radicals are one of the main active species produced by these plasmas. Present study deals with the investigation of RF atmospheric pressure plasma jet in terms of OH radicals production by admixture of H 2 O into argon used as a feed gas. Generation of OH radicals is studied by laser-induced fluorescence spectroscopy. The excitation dynamics of OH radicals induced by the laser photons is studied by time-resolved spectroscopy. It is shown that vibrational and rotational energy transfer processes, which are sensitive to the surrounding species, can lead to the complication in the OH radicals diagnostics at high pressure and have to be considered during experiments. The axial and radial 2D maps of absolute densities of hydroxyl radicals at different water contents are obtained. The highest density of 1.15 Â 10 20 m À3 is measured in the plasma core for the case of 0.3% H 2 O. In the x-y-plane, the OH density steeply decreases within a range of 62 mm from its maximum value down to 10 18 m À3 . The effect of H 2 O addition on the generation of OH radicals is investigated and discussed. V C 2013 AIP Publishing LLC. [http://dx

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Section: -6supporting

confidence: 58%

“…while at low water contents the quenching of OH(A) by N 2 and O 2 (appearing in the discharge zone due to backdiffusion of air) plays an important role 18 OHðAÞ…”

Section: Resultsmentioning

confidence: 99%

Section: -4mentioning

confidence: 99%

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OH radicals distribution in an Ar-H2O atmospheric plasma jet

Nikiforov

Xiong

et al. 2013

Physics of Plasmas

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“…The decay time can be calculated from where k Q (T ) is the temperature dependent quenching rate [41] and τ rad the radiative lifetime of OH(A-X). The calculated decay times shown in figure 9 are calculated for the temperature measured using LIF (see figure 4).…”

Section: Time-resolved Collisional Quenchingmentioning

confidence: 99%

Time-resolved absolute OH density of a nanosecond pulsed discharge in atmospheric pressure He–H₂O: absolute calibration, collisional quenching and the importance of charged species in OH production

Verreycken

Sadeghi

Bruggeman

2014

Plasma Sources Sci. Technol.

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Link to publication Citation for published version (APA):Verreycken, T., Sadeghi, N., & Bruggeman, P. J. (2014). Time-resolved absolute OH density of a nanosecond pulsed discharge in atmospheric pressure He-H2O : absolute calibration, collisional quenching and the importance of charged species in OH production. Plasma Sources Science and Technology, 23(4), 45005-1/9. DOI: 10.1088/0963-0252/23/4/045005 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. AbstractThe time-resolved OH density in a nanosecond pulsed filamentary discharge in an atmospheric pressure He-H 2 O(0.05%) mixture is measured using laser induced fluorescence. The lifetime of the excited OH(A) state is found to be strongly time dependent during the plasma pulse, with the shortest decay time occurring at the moment the plasma is switched off. The measured LIF intensity is corrected for this time-resolved quenching and calibrated using Rayleigh scattering. Time-resolved electron density (n max e = (7.6 ± 0.8) × 10 21 m −3 ), He ( 3 S 1 ) metastable density (He max m = (1.6 ± 0.3) × 10 20 m −3 ), gas temperature (T max g = (350 ± 60) K) and optical emission are presented and used in the interpretation of the observed time dependence of the OH density. Based on these experimental data, it is shown that for the present discharge conditions, OH is mainly produced by charge transfer reactions to water followed by dissociative recombination of the water ion. In addition, two often encountered issues with the calibration of OH LIF are highlighted with an example.

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“…The slope of the curve allows one to determine a quenching coefficient which can be displayed in units of cm 3 s −1 with the ideal gas law using the measured gas temperature of T = 300 K. It is worth noting that quenching coefficients have usually a non-trivial temperature dependence [7] apart from this unit conversion. The natural lifetime is determined from the crossing point of the curve with the Y -axis.…”

Section: Natural Lifetimes and Quenching Coefficientsmentioning

confidence: 99%

Absolute calibration of atomic density measurements by laser-induced fluorescence spectroscopy with two-photon excitation

Niemi

Gathen

Döbele

2001

J. Phys. D: Appl. Phys.

277

350

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The two-photon resonances of atomic hydrogen (λ = 2 × 205.1 nm), atomic nitrogen (λ = 2 × 206.6 nm) and atomic oxygen (λ = 2 × 225.6 nm) are investigated together with two selected transitions in krypton (λ = 2 × 204.2 nm) and xenon (λ = 2 × 225.5 nm). The natural lifetimes of the excited states, quenching coefficients for the most important collisions partners, and the relevant ratios of the two-photon excitation cross sections are measured. These data can be applied to provide a calibration for two-photon laser-induced fluorescence measurements based on comparisons with spectrally neighbouring noble gas resonances.

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A model for temperature-dependent collisional quenching of OHA2∑+

Cited by 138 publications

References 42 publications

OH radicals distribution in an Ar-H2O atmospheric plasma jet

OH radicals distribution in an Ar-H2O atmospheric plasma jet

Time-resolved absolute OH density of a nanosecond pulsed discharge in atmospheric pressure He–H₂O: absolute calibration, collisional quenching and the importance of charged species in OH production

Absolute calibration of atomic density measurements by laser-induced fluorescence spectroscopy with two-photon excitation

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A model for temperature-dependent collisional quenching of OHA2∑+

Cited by 138 publications

References 42 publications

OH radicals distribution in an Ar-H2O atmospheric plasma jet

OH radicals distribution in an Ar-H2O atmospheric plasma jet

Time-resolved absolute OH density of a nanosecond pulsed discharge in atmospheric pressure He–H2O: absolute calibration, collisional quenching and the importance of charged species in OH production

Absolute calibration of atomic density measurements by laser-induced fluorescence spectroscopy with two-photon excitation

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Time-resolved absolute OH density of a nanosecond pulsed discharge in atmospheric pressure He–H₂O: absolute calibration, collisional quenching and the importance of charged species in OH production