Electron-mediated vibration–electronic (V–E) energy transfer in optically pumped plasmas

Plönjes, Elke; Palm, Peter; Rich, John Martin; Adamovich, Igor V.; Urban, W.

doi:10.1016/s0301-0104(02)00387-7

Cited by 23 publications

(26 citation statements)

References 27 publications

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“…This assumption is a consequence of the long time-life of N( 4 S) atoms and of the relatively small energy threshold for the excitation of the N( 2 D) state. However, the possibility that the V-E energy transfer processes may also occur as a result of collisions of highly excited vibrational N 2 molecules with slow electrons, as is the case of energy transfer in CO laser pumped plasmas with the mechanism e( + ) + CO(X 1 , v) → e( ) + CO(A 1 , v ) [27], should be questioned. As noted in [27], this effect in CO may occur at ionization degrees as low as ∼10 −9 -10 −7 .…”

Section: Discussionmentioning

confidence: 99%

“…In particular, we have only made a single adjustment, related to the rate coefficients for V-T(N 2 -N) collisions, and have further included reactions (10), (13) and (14). A different possibility for the observed discrepancy may be related to the absence in the model of reactions of the type of (13) and (14) but with the presence of electrons instead of N( 4 S) atoms, as experimentally observed for CO in [27], such as e( + ) + N 2 (X, v) → e( ) + N 2 (A, B, a ).…”

Section: Reference Modelmentioning

confidence: 99%

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Self-consistent kinetic model of the short-lived afterglow in flowing nitrogen

Sá¹,

Guerra²,

Loureiro³

et al. 2003

J. Phys. D: Appl. Phys.

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A detailed kinetic model for the flowing nitrogen microwave discharge and post-discharge is developed with the aim of gaining a deeper understanding into the processes responsible for the formation of the short-lived afterglow of nitrogen and for the enhancement of the concentration of N 2 (A 3 + u ) metastable, measured at approximately the same position in Sadeghi et al J. Phys. D: Appl. Phys. 34 1779. The present work shows that the peaks observed in the afterglow, for the density of molecules in radiative N 2 (B 3 g ) and N + 2 (B 2 + u ) and metastable N 2 (A 3 + u ) states, can be explained as a result of a pumping-up phenomenon into the vibrational ladder produced by near-resonant V-V energy-exchange collisions, involving vibrationally excited molecules N 2 (X 1 + g , v) in levels as high as v ∼ 35. The present predictions are shown to be in good agreement with the measured concentrations for N 2 (A 3 + u ) metastables and N( 4 S) atoms, and with the emission intensities of 1 + and 1 − system bands of N 2 .

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Section: Discussionmentioning

confidence: 99%

Section: Reference Modelmentioning

confidence: 99%

Self-consistent kinetic model of the short-lived afterglow in flowing nitrogen

Sá¹,

Guerra²,

Loureiro³

et al. 2003

J. Phys. D: Appl. Phys.

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show abstract

“…and will not be discussed here. Nevertheless, it is worth noting that the recent experiments reported in [10,11] show beyond doubt that electron mediated V-E processes occur in CO, at ionization degrees as low as 10 −9 -10 −7 . For this reason we suggested in [6] and confirmed in [7] that resonant electron mediated vibration-electronic V-E energy transfers may contribute as well to the formation of electronically excited states in the nitrogen afterglow.…”

Section: Kinetic Modelmentioning

confidence: 95%

“…This originates a climbing in the vibrational ladder during the relaxation process in the afterglow [9]. The highly vibrationally excited dark states N 2 (X 1 Σ + g , v) formed in this way subsequently transfer their energy to electronically excited states through vibration-electronic (V-E) energy transfer processes that can be mediated by heavy-particles (such as N( 4 S) atoms) and/or electrons [8,10,11]. The key point is the formation of N 2 (A 3 Σ + u ) and N 2 (a 1 Σ − u ) locally in the afterglow, which are then involved in a series of reactions of formation of other species [7,8].…”

Section: Introductionmentioning

confidence: 99%

Nitrogen pink afterglow: the mystery continues

Guerra¹,

Sá

Loureiro³

2007

J. Phys.: Conf. Ser.

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This work extends our previous analysis of the nitrogen pink afterglow, by comparing our model predictions with the recently reported measurements of metastable N( 2 P ) atoms and N2(a 1 Πg) molecules. It is shown that both species reveal the presence of a characteristic maximum on their populations, occurring downstream from the discharge after an initial stage of decrease. Such behavior is a consequence of the V-V pumping-up mechanism taking place during the relaxation in the afterglow, which is followed by V-E transfers that create locally N2(A 3 Σ + u ) and N2(a 1 Σ − u ) metastables. The model predictions significantly overestimate the density of the N2(a 1 Πg) state, revealing a problem in the description of the singlet kinetics. As singlet N2(a 1 Σ − u ) metastables play a crucial role in nitrogen ionization, the new results imply that the ionization mechanisms in the afterglow may have to be reviewed.

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“…Nevertheless, these excited electronic states must be taken into account if radiative intensities from the first positive N 2 system [58] are expected to be evaluated accurately. Note that vibration-electronic transitions observed for CO molecules [59,60] may effectively increase the concentration of excited electronic levels in the present modeling. Unfortunately, data for VE jumps related to N 2 molecules are not available to our knowledge.…”

Section: Distance Behind the Shock (Cm) Vibrational Temperature T ( Xmentioning

confidence: 78%

Simple model for vibration-translation exchange at high temperatures: Effects of multiquantum transitions on the relaxation of aN2gas flow behind a shock

2011

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In this paper a simple model is proposed for computation of rate coefficients related to vibration-translation transitions based on the forced harmonic oscillator theory. This model, which is developed by considering a quadrature method, provides rate coefficients that are in very good agreement with those found in the literature for the high temperature regime (≳10,000 K). This model is implemented to study a one-dimensional nonequilibrium inviscid N(2) flow behind a plane shock by considering a state-to-state approach. While the effects of ionization and chemical reactions are neglected in our study, our results show that multiquantum transitions have a great influence on the relaxation of the macroscopic parameters of the gas flow behind the shock, especially on vibrational distributions of high levels. All vibrational states are influenced by multiquantum processes, but the effective number of transitions decreases inversely according to the vibrational quantum number. For the initial conditions considered in this study, excited electronic states are found to be weakly populated and can be neglected in modeling. Moreover, the computing time is considerably reduced with the model described in this paper compared to others found in the literature.

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Electron-mediated vibration–electronic (V–E) energy transfer in optically pumped plasmas

Cited by 23 publications

References 27 publications

Self-consistent kinetic model of the short-lived afterglow in flowing nitrogen

Self-consistent kinetic model of the short-lived afterglow in flowing nitrogen

Nitrogen pink afterglow: the mystery continues

Simple model for vibration-translation exchange at high temperatures: Effects of multiquantum transitions on the relaxation of aN2gas flow behind a shock

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