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

Plönjes, Elke; Palm, Peter; Chernukho, Andrey; Adamovich, Igor V.; Rich, John Martin

doi:10.1016/s0301-0104(00)00096-3

Cited by 73 publications

(26 citation statements)

References 35 publications

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“…These spectra, shown on the same scale, are used to infer CO vibrational level populations, as discussed in detail in Ref. [52]. CO fundamental emission spectra, taken at the same conditions, are used for translational-rotational temperature inference.…”

Section: Resultsmentioning

confidence: 99%

Electrically Excited, Supersonic Flow Carbon-Monoxide Laser with Air Species in Laser Mixture

Yurkovich

Eckert

Jans

et al. 2018

Journal of Propulsion and Power

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Performance parameters of an electric discharge excited, supersonic flow CO laser operated with significant amounts of air species in the laser mixture is studied experimentally and by kinetic modeling. The results demonstrate that adding nitrogen to the CO-He mixture increases the laser power significantly, by up to a factor of 3. Adding oxygen reduces CO vibrational excitation and results in a steep laser power reduction. Adding air to the laser mixture also produces higher output power, such that the positive effect of nitrogen outweighs the negative effect of oxygen. This result indicates that a chemical CO laser, not dependent on the electric discharge for excitation, may be capable of operating in a mixture of carbon vapor and air. Performance of a supersonic flow chemical laser excited by a reaction of carbon vapor and molecular oxygen is analyzed by kinetic modeling. Peak laser power is predicted at the C vapor mole fraction of 0.2%, when 15% of energy stored in CO vibrational energy mode (4.5% of the reaction enthalpy) is converted to laser power. At higher C vapor mole fractions, flow temperature rise caused by exothermic reactions and by CO vibrational relaxation results in rapid reduction of the predicted laser power.

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Section: Resultsmentioning

confidence: 99%

Electrically Excited, Supersonic Flow Carbon-Monoxide Laser with Air Species in Laser Mixture

Yurkovich

Eckert

Jans

et al. 2018

Journal of Propulsion and Power

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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%

“…The V-V processes then continue to populate higher vibrational levels of CO as well as vibrational levels of N 2 , which are not coupled to the laser radiation, [20][21][22] CO͑v…”

Section: Methodsmentioning

confidence: 99%

“…In steady-state conditions, when the average vibrational mode energy of the CO would correspond to several thousand degrees Kelvin, the temperature never rises above a few hundred degrees. [20][21][22] Thus a strong disequipartition of energy can be maintained in the cell, characterized by very high energy of the vibrational modes and a low translational/ rotational mode temperature. The population of vibrational states of CO in the cell is monitored by infrared emission spectroscopy.…”

Section: Methodsmentioning

confidence: 99%

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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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“…The reaction of Cl ( 2 P) atoms, produced by laser photolysis of chlorine, with CH 4 was monitored 28 by means of a multipass absorption cell coupled to the TR-FT spectrometer. Vibration-to-vibration energy transfer between CO molecules, 29 between SO 2 and SF 6 30 and other gases, 31 and rotational energy transfer in excited electronic states of CH by collisions with different rare gases and molecules 32 have been studied and analysed. Rovibronic state-to-state energy transfer has also been investigated in detail in an excited electronic state of NH 2 .…”

Section: Applications Of Fourier Transform Interferometersmentioning

confidence: 99%

3 Gas-phase molecular spectroscopy

Crozet

Ross

Vervloët

2002

Annu. Rep. Prog. Chem., Sect. C: Phys. Chem.

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

Cited by 73 publications

References 35 publications

Electrically Excited, Supersonic Flow Carbon-Monoxide Laser with Air Species in Laser Mixture

Electrically Excited, Supersonic Flow Carbon-Monoxide Laser with Air Species in Laser Mixture

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

3 Gas-phase molecular spectroscopy

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