Proton transfer chains in cold plasmas of H2with small amounts of N2. The prevalence of NH4+

Carrasco, Esther; Tanarro, Isabel; Herrero, Vı́ctor J.; Cernicharo, J.

doi:10.1039/c2cp43438e

Cited by 24 publications

(41 citation statements)

References 51 publications

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“…A similar extensive study of H 2 -N 2 plasmas as in the present work was carried out by Carrasco et al 3,27,28 in a DC hollow cathode discharge with comparable plasma conditions. Carrasco et al presented experimental and modeling results for densities of ionic, electron, radical and gas species.…”

Section: Introductionmentioning

confidence: 71%

Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

Sode

Jacob

Schwarz-Selinger

et al. 2015

Journal of Applied Physics

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A comprehensive experimental investigation of absolute ion and neutral species densities in an inductively coupled H 2 -N 2 -Ar plasma was carried out. Additionally, the radical and ion densities were calculated using a zero-dimensional rate equation model. The H 2 -N 2 -Ar plasma was studied at a pressure of 1.5 Pa and an rf power of 200 W. The N 2 partial pressure fraction was varied between f N 2 = 0 % and 56 % by a simultaneous reduction of the H 2 partial pressure fraction. The Ar partial pressure fraction was held constant at about 1 %. NH 3 was found to be produced almost exclusively on the surfaces of the chamber wall. NH 3 contributes up to 12 % to the background gas.To calculate the radical densities with the rate equation model it is necessary to know the corresponding wall loss times t wrad of the radicals. t wrad was determined by the temporal decay of radical densities in the afterglow with ionization threshold mass spectrometry during pulsed operation and based on these experimental data the absolute densities of the radical species were calculated and compared to measurement results.Ion densities were determined using a plasma monitor (mass and energy resolved mass spectrometer). H + 3 is the dominant ion in the range of 0.0 ≤ f N 2 < 3.4 %. For 3.4 < f N 2 < 40 % NH + 3 and NH + 4 are the most abundant ions and agree with each other within the experimental uncertainty. For f N 2 = 56 % N 2 H + is the dominant ion while NH + 3 and NH + 4 have only a slightly lower density. Ion species with densities in the range between 0.5 and 10 % of n i,tot are H + 2 , ArH + , and NH + 2 . Ion species with densities less than 0.5 % of n i,tot are H + , Ar + , N + , and NH + . Our model describes the measured ion densities of the H 2 -N 2 -Ar plasma reasonably well. The ion chemistry, i.e., the production and loss processes of the ions and radicals, are discussed in detail. The main features, i.e., the qualitative abundance of the ion species and the ion density dependence on the N 2 partial pressure fraction, are well reproduced by the model.

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Section: Introductionmentioning

confidence: 71%

Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

Sode

Jacob

Schwarz-Selinger

et al. 2015

Journal of Applied Physics

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“…Similar models applied to H 2 +D 2 , H 2 +N 2 and H 2 +Ar discharges can be found in refs. [37][38][39][40]. The model accounts for the main physico-chemical processes: electron impact dissociation and ionization, ion-molecule and ion-ion reactions, neutralization at the wall and heterogeneous chemistry.…”

Section: Modelmentioning

confidence: 99%

“…In the steady state, a small fraction of these hot atoms survives and can be detected either in the line profiles of Balmer emission lines of H atoms [81] or indirectly in the energy resolved mass spectra of H + and O + ions [81][82][83]. However, previous works carried out on this reactor for different gas mixtures at comparable pressures [33,34,[36][37][38][39] have shown that the assumption of a Maxwellian distribution is not a bad approximation for the global kinetics, and we have adopted it here for lack of better information on the actual eedf. The limitations of this approximation should be taken into account in the interpretation of the results.…”

Section: Modelmentioning

confidence: 99%

“…In agreement with these studies, the flux of atoms (O and H) and radicals (OH) to the surface wall dominate the heterogeneous chemistry including both adsorption and recombination via Eley-Rideal (ER) reactions. The γ ER selected for H 2 is 3.5×10 −3 (taken from reference [39]) and a value of 2.4×10 −2 is estimated for O 2 , above the value considered for N 2 in [39]. This assumption is based on results from [86], where higher wall recombination coefficients are obtained from O radicals than from N radicals on stainless steel.…”

Section: Modelmentioning

confidence: 99%

“…Dissociative adsorption of O 2 at the walls, which has been experimentally studied by molecular beams and modelled on clean Fe surfaces [87,88], has been tested with model simulations and has very small influence on the present H 2 / O 2 plasmas. In previous works [37][38][39], adsorptions of neutral molecules were considered negligible as compared with those of atoms and radicals. Literature calculations suggest that the adsorption of water on surface iron atoms can take place without a barrier [89,90].…”

Section: Modelmentioning

confidence: 99%

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Chemistry in glow discharges of H₂/O₂mixtures: diagnostics and modelling

Jiménez-Redondo¹,

Carrasco²,

Herrero³

et al. 2015

Plasma Sources Sci. Technol.

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The chemistry of low pressure H 2 + O 2 discharges with different mixture ratios has been studied in a hollow cathode DC reactor. Neutral and positive ion distributions have been measured by mass spectrometry, and Langmuir probes have been used to provide charge densities and electron temperatures. A simple zero order kinetic model including neutral species and positive and negative ions, which takes into account gas-phase and heterogeneous chemistry, has been used to reproduce the global composition of the plasmas over the whole range of mixtures experimentally studied, and allows for the identification of the main physicochemical mechanisms that may explain the experimental results. To our knowledge, no combined experimental and modelling studies of the heavy species kinetics of low pressure H 2 + O 2 plasmas including ions has been reported before.As expected, apart from the precursors, H 2 O is detected in considerable amounts. The model also predicts appreciable concentrations of H and O atoms and the OH radical. The relevance of the metastable species O( 1 D) and O 2 (a 1 Δ g ) is analysed. Concerning the charged species, positive ion distributions are dominated by H 3 O + for a wide range of intermediate mixtures, while H 3 + and O 2 + are the major ions for the higher and lower H 2 /O 2 ratios, respectively. The mixed ions OH + , H 2 O + and HO 2 + are also observed in small amounts. Negative ions are shown to have a limited relevance in the global chemistry; their main contribution is the reduction of the electron density available for electron impact processes.

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Proton transfer chains in cold plasmas of H₂with small amounts of N₂. The prevalence of NH₄⁺

Abstract: The ion-molecule chemistry of the astronomically relevant H

Cited by 24 publications

References 51 publications

Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

Chemistry in glow discharges of H₂/O₂mixtures: diagnostics and modelling

Nitrogen–carbon-induced spinodal structure in plasma nitrocarburized 38CrMoAl with hollow cathode discharging

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Proton transfer chains in cold plasmas of H2with small amounts of N2. The prevalence of NH4+

Abstract: The ion-molecule chemistry of the astronomically relevant H

Cited by 24 publications

References 51 publications

Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

Measurement and modeling of neutral, radical, and ion densities in H2-N2-Ar plasmas

Chemistry in glow discharges of H2/O2mixtures: diagnostics and modelling

Nitrogen–carbon-induced spinodal structure in plasma nitrocarburized 38CrMoAl with hollow cathode discharging

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Product

Resources

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Proton transfer chains in cold plasmas of H₂with small amounts of N₂. The prevalence of NH₄⁺

Chemistry in glow discharges of H₂/O₂mixtures: diagnostics and modelling