Vibrational and electronic excitation of nitric oxide in optical pumping experiments

Saupe, Stephan; Adamovich, Igor V.; Grassi, Michael J.; Rich, John Martin; Bergman, R. C.

doi:10.1016/0301-0104(93)87006-9

Cited by 38 publications

(16 citation statements)

References 16 publications

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“…This originates a climbing in the vibrational ladder as the e-V collisions cease to be effective [28,168]. The V-V up-pumping in the vibrational relaxation of anharmonic oscillators also exists for other diatomic molecules, such as CO(X 1 Σ + ) [169,170] and NO(X 2 Π r ) [171]. Figure 20 shows the VDFs of N 2 (X 1 Σ + g , v) molecules calculated at different afterglow times between 0 and 1 s, clearly illustrating the V-V pumping of the high v levels.…”

Section: Vibrational Kineticsmentioning

confidence: 95%

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Kinetic modeling of low-pressure nitrogen discharges and post-discharges

Guerra¹,

Sá

Loureiro³

2004

Eur. Phys. J. Appl. Phys.

223

251

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The kinetic modeling of low-pressure (p ∼ 1−10 torr) stationary nitrogen discharges and the corresponding afterglows is reviewed. It is shown that a good description of the overall behavior of nitrogen plasmas requires a deep understanding of the coupling between different kinetics. The central role is played by ground-state vibrationally excited molecules, N2(X 1 Σ + g , v), which have a strong influence on the shape of the electron energy distribution function, on the creation and destruction of electronically excited states, on the gas heating, dissociation and on afterglow emissions. N2(X 1 Σ + g , v) molecules are actually the hinge ensuring a strong link between the various kinetics. The noticeable task done by electronically excited metastable molecules, in particular N2(A 3 Σ + u) and N2(a 1 Σ − u), is also pointed out. Besides contributing to the same phenomena as vibrationally excited molecules, these electronic metastable states play also a categorical role in ionization. Furthermore, vibrationally excited molecules in high v levels are in the origin of the peaks observed in the flowing afterglow for the concentrations of several species, such as N2(A 3 Σ + g), N2(B 3 Πg), N + 2 (B 2 Σ + u) and electrons, which occur downstream from the discharge after a dark zone as a consequence of the V-V up-pumping mechanism.

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Section: Vibrational Kineticsmentioning

confidence: 95%

“…The experimental data is from [151] with the correction factor of 5 pointed out in [173]. [171,176]. However, these V-E processes are far from generating consensus.…”

Section: Chemical Kineticsmentioning

confidence: 99%

Kinetic modeling of low-pressure nitrogen discharges and post-discharges

Guerra¹,

Sá

Loureiro³

2004

Eur. Phys. J. Appl. Phys.

223

251

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“…(1) among the high vibrational quantum levels (v-w, v,w>>l) are of particular importance, since molecules on the high vibrational levels can also participate in nonequilibrium chemical reactions, as well as produce electronic excitation and ionization. In particular, the vibration-to-electronic (V-E) processes, in which energy is transferred from highly vibrationally excited levels of the ground electronic state to a low-lying excited electronic state, with subsequent ultraviolet and visible band radiation, have and NO [9,10]. Ionization in collisions of two vibrationally excited CO molecules pooling their energies together has been studied in [ 11,121.…”

Section: Introductionmentioning

confidence: 99%

Time-resolved Fourier-transform infrared spectroscopy of optically pumped carbon monoxide

Plönjes

Palm

Chernukho

et al. 1999

30th Plasmadynamic and Lasers Conference

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The paper discusses measurements of vibration-to-vibration (V-V) energy transfer rates for CO-CO using time-resolved step-scan Fourier transform infrared spectroscopy of optically pumped carbon monoxide. In the experiments, time evolution of all vibrational states of carbon monoxide excited by a CO laser and populated by V-V processes (up to v-40) is monitored simultaneously for the first time. The V-V rates are inferred from these data using a kinetic model that incorporates spatial power distribution of the focused laser beam, transport processes, and multi-quantum V-V processes. Although the model predictions agree well with the timedependent step-scan relaxation data, there is variance between the model predictions and the uppumping data, however. Comparison of calculations using two different sets of V-V rates with experimental spectra showed that the use of the semi-empirical V-V rates of DeLeon and Rich provides better agreement with experiment. It is also shown that the multi-quantum V-V rates among high vibrational quantum numbers, calculated by Cacciatore and Billing, are substantially overpredicted. The results provide some new insight into nonequilibrium vibrational kinetics, ' and also demonstrate the capabilities of the step-scan Fourier transform spectroscopy for timeresolved studies of molecular energy transfer processes and validation of theoretical rate models.

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“…The present use of the CO laser to excite high-pressure gas mixtures is a further development of a technique with a considerable literature. [14][15][16][17][18][19][20][21][22] The low vibrational states of CO, vр10, are populated by direct resonance absorption of CO pump laser radiation in combination with the rapid redistribution of population by vibration-vibration (V-V) exchange processes, 23 CO͑v ͒ϩCO͑ w ͒→CO͑ vϪ1 ͒ϩCO͑ wϩ1 ͒. ͑2͒…”

Section: Methodsmentioning

confidence: 99%

Radio frequency energy coupling to high-pressure optically pumped nonequilibrium plasmas

Plönjes

Palm

Lee

et al. 2001

Journal of Applied Physics

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This article presents an experimental demonstration of a high-pressure unconditionally stable nonequilibrium molecular plasma sustained by a combination of a continuous wave CO laser and a sub-breakdown radio frequency ͑rf͒ electric field. The plasma is sustained in a CO/N 2 mixture containing trace amounts of NO or O 2 at pressures of Pϭ0.4-1.2 atm. The initial ionization of the gases is produced by an associative ionization mechanism in collisions of two CO molecules excited to high vibrational levels by resonance absorption of the CO laser radiation with subsequent vibration-vibration (V-V) pumping. Further vibrational excitation of both CO and N 2 is produced by free electrons heated by the applied rf field, which in turn produces additional ionization of these species by the associative ionization mechanism. In the present experiments, the reduced electric field, E/N, is sufficiently low to preclude field-induced electron impact ionization. Unconditional stability of the resultant cold molecular plasma is enabled by the negative feedback between gas heating and the associative ionization rate. Trace amounts of nitric oxide or oxygen added to the baseline CO/N 2 gas mixture considerably reduce the electron-ion dissociative recombination rate and thereby significantly increase the initial electron density. This allows triggering of the rf power coupling to the vibrational energy modes of the gas mixture. Vibrational level populations of CO and N 2 are monitored by infrared emission spectroscopy and spontaneous Raman spectroscopy. The experiments demonstrate that the use of a sub-breakdown rf field in addition to the CO laser allows an increase of the plasma volume by about an order of magnitude. Also, CO infrared emission spectra show that with the rf voltage turned on the number of vibrationally excited CO molecules along the line of sight increase by a factor of 3-7. Finally, spontaneous Raman spectra of N 2 show that with the rf voltage the vibrational temperature of nitrogen increases by up to 30%. This novel energy efficient approach allows sustaining large-volume high-pressure molecular plasmas without the use of a high-power CO laser. This opens a possibility of using the present technique for high-yield plasma chemical synthesis and plasma material processing.

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Vibrational and electronic excitation of nitric oxide in optical pumping experiments

Cited by 38 publications

References 16 publications

Kinetic modeling of low-pressure nitrogen discharges and post-discharges

Kinetic modeling of low-pressure nitrogen discharges and post-discharges

Time-resolved Fourier-transform infrared spectroscopy of optically pumped carbon monoxide

Radio frequency energy coupling to high-pressure optically pumped nonequilibrium plasmas

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