Vibrational excitation in H2 and D2 electric discharges

Shirley, John A.; Hall, R. J.

doi:10.1063/1.435213

Cited by 26 publications

(16 citation statements)

References 17 publications

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“…CARS spectroscopy has become a well-established method. Many experiments are described on establishing of the gas, rotational and vibrational temperatures of H2 molecules in discharge plasmas (Dedic et al, 2017;Lempert & Adamovich, 2014;Shirley & Hall, 1977;Yatom et al, 2013) including concentration measurement (Jensen et al, 2019;Kearney et al, 2013;Ran et al, 2019;Regnier et al, 1974) by utilizing CARS method. CARS has similarly been employed in part to accomplish for preparing the oriented and aligned H2 and HD molecules using stimulated Raman pumping (Bartlett et al, 2008;Choi et al, 2019;Folick et al, 2011;Lim et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

Raman Excitation of Hydrogen Molecules to v = 1 State

Candan

2021

Iğdır Üniversitesi Fen Bilimleri Enstitüsü Dergisi

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Coherent anti-Stokes Raman scattering (CARS) can reveal a molecule’s vibrational spectrum to a great extent. Instantaneous interaction of Stokes and pump beams stemming from powerful pulsed lasers excites a molecule’s vibrational modes in CARS. In this technique, combining two visible laser beams could create spectra resonances relating to vibrational transitions. In this work, Raman excitation of Hydrogen molecules to v = 1 state is achieved by CARS spectroscopy. CARS measurements are successfully carried out for H2 S-branch and Q-branch transitions using our laser system. This measurement proves the feasibility of CARS experiment which could be employed to excite molecules to a specific rovibrational state. Moreover, experiments conducted for CARS signal with respect to various gas pressures differing between 200 and 600 torr for S-branch transition of H2 molecule.

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Section: Discussionmentioning

confidence: 99%

Raman Excitation of Hydrogen Molecules to v = 1 State

Candan

2021

Iğdır Üniversitesi Fen Bilimleri Enstitüsü Dergisi

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“…CARS is probably the most used method for obtaining information on vibrational and rotational temperatures of H 2 and D 2 plasmas under different conditions including DC discharges [10,11], multipole magnetic [12] and RF plasmas [13,14]. In this paper, we report a sample of results recently obtained by our group under RF inductive plasma conditions [13,14] as well as the theoretical model used for rationalizing the results.…”

Section: Coherent Anti-stokes Raman Spectroscopymentioning

confidence: 96%

From cold to fusion plasmas: spectroscopy, molecular dynamics and kinetic considerations

Capitelli¹,

Celiberto²,

Colonna³

et al. 2010

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

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Abstract. Non-equilibrium effects in hydrogen plasmas have been investigated in different systems, ranging from RF plasmas to corona discharges. Existing measurements of vibrational and rotational temperatures, obtained by different spectroscopical techniques are reported, rationalized by results calculated by kinetic models. Input data of these models are discussed with particular attention on the dependence of relevant cross sections on the vibrational quantum number. Moreover the influence of vibrational excitation of the H 2 molecules in affecting the translational distribution of atoms in ground and excited levels is shown. Finally a collisional radiative model for atomic hydrogen levels, based on the coupling of the Boltzmann equation for EEDF and the excited state kinetics, is presented, emphasizing the limits of quasi-stationary approximation. In this last case, large deviations of the EEDF and atomic level distributions from the equilibrium are observed.

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“…( ) is obtained from the calibration with gases presented above. It enables to deduce the partial pressure of the neutral species measured by the MS using equation (3). Nevertheless, concerning the measurements of positive ions by the MS, the transmittance to use is ( ) (see next section).…”

Section: Calibration For Neutralsmentioning

confidence: 99%

N₂–H₂ capacitively coupled radio-frequency discharges at low pressure. Part I. Experimental results: effect of the H₂ amount on electrons, positive ions and ammonia formation

Chatain

Jiménez-Redondo

Vettier

et al. 2020

Plasma Sources Sci. Technol.

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The mixing of N2 with H2 leads to very different plasmas from pure N2 and H2 plasma discharges. Numerous issues are therefore raised involving the processes leading to ammonia (NH3) formation. The aim of this work is to better characterize capacitively-coupled radiofrequency plasma discharges in N2 with few percents of H2 (up to 5%), at low pressure (0.3 to 1 mbar) and low coupled power (3 to 13 W). Both experimental measurements and numerical simulations are performed. For clarity, we separated the results in two complementary parts. The actual one (first part), presents the details on the experimental measurements, while the second focuses on the simulation, a hybrid model combining a 2D fluid module and a 0D kinetic module. Electron density is measured by a resonant cavity method. It varies from 0.4 to 5.10 9 cm-3 , corresponding to ionization degrees from 2.10-8 to 4.10-7. Ammonia density is quantified by combining IR absorption and mass spectrometry. It increases linearly with the amount of H2 (up to 3.10 13 cm-3 at 5% H2). On the contrary, it is constant with pressure, which suggests the dominance of surface processes on the formation of ammonia. Positive ions are measured by mass spectrometry. Nitrogen-bearing ions are hydrogenated by the injection of H2, N2H + being the major ion as soon as the amount of H2 is > 1%. The increase of pressure leads to an increase of secondary ions formed by ion/radicalneutral collisions (ex: N2H + , NH4 + , H3 +), while an increase of the coupled power favors ions formed by direct ionization (ex: N2 + , NH3 + , H2 +).

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Vibrational excitation in H2 and D2 electric discharges

Cited by 26 publications

References 17 publications

Raman Excitation of Hydrogen Molecules to v = 1 State

Raman Excitation of Hydrogen Molecules to v = 1 State

From cold to fusion plasmas: spectroscopy, molecular dynamics and kinetic considerations

N₂–H₂ capacitively coupled radio-frequency discharges at low pressure. Part I. Experimental results: effect of the H₂ amount on electrons, positive ions and ammonia formation

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Vibrational excitation in H2 and D2 electric discharges

Cited by 26 publications

References 17 publications

Raman Excitation of Hydrogen Molecules to v = 1 State

Raman Excitation of Hydrogen Molecules to v = 1 State

From cold to fusion plasmas: spectroscopy, molecular dynamics and kinetic considerations

N2–H2 capacitively coupled radio-frequency discharges at low pressure. Part I. Experimental results: effect of the H2 amount on electrons, positive ions and ammonia formation

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N₂–H₂ capacitively coupled radio-frequency discharges at low pressure. Part I. Experimental results: effect of the H₂ amount on electrons, positive ions and ammonia formation