OH detection and spectroscopy by DFWM in flames; comparison with CARS

Bervas, H.; Attal‐Trétout, Brigitte; Boiteux, S. Le; Taran, J. P.

doi:10.1088/0953-4075/25/5/010

Cited by 34 publications

(11 citation statements)

References 38 publications

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“…This allowed the linewidths and lineshapes of each transition involved to be studied independently and enabled the contributions from stray light and non-resonant four-wave mixing processes to be 70 modelled. OH radicals were also involved in several works where resonantly enhanced CARS was compared to DFWM [60,145] However, more recently, the interest in using CARS for intermediate and minor species detection has experienced a kind of renaissance. In particular the dual-pump CARS approach illustrated in figure 5.2b where the probe laser wavelength is tuned to an electronic transition of the species under investigation was employed to study nitric oxide [132,[156][157][158][159] and acetylene [160].…”

Section: Molecular Physics Applicationsmentioning

confidence: 99%

“…Attal-Tretout and co-workers who used a non-perturbative approach to treat pump saturation and atomic motion effects in the FPG which led to modification of the signal lineshapes [60,61]. Their analytical result however was found to work only for unsaturating probes and provided the pumps were not strongly saturating.…”

Section: Analysis Of Dfwm Signals: Practical Considerationsmentioning

confidence: 99%

Section: Molecular Physics Applicationsmentioning

confidence: 99%

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Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

131

112

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Laser-based methods have transformed combustion diagnostics in the past few decades. The high intensity, coherence, high spectral resolution and frequency tunability available from laser radiation has provided powerful tools for studying microscopic processes and macroscopic phenomena in combustion by linear and nonlinear optical processes. This review focuses on nonlinear optical techniques based on resonant four-wave mixing for non-intrusive measurements of minor species in combustion. The importance of minor species such as reaction intermediates is outlined together with the challenges they present for detection and measurement in the hostile environments of flames, technical combustors, and engines. The limitations of conventional optical methods for such measurements are described and the particular advantages of coherent methods using nonlinear optical techniques are discussed.The basic physics underlying four-wave wave mixing processes and theoretical models for signal calculation are then presented together with a discussion of how combustion parameters may be derived from analysis of signals generated in various four-wave mixing processes. The most important four-wave mixing processes, in this context, are then reviewed:Degenerate Four-Wave Mixing (DFWM), Coherent Anti-Stokes Raman Scattering (CARS), Laser Induced Grating Spectroscopy (LIGS) and Polarization Spectroscopy (PS). In each case the fundamental physics is outlined to explain the particular properties and diagnostic advantages of each technique. The application of the methods mentioned to molecular physics studies of combustion species is then reviewed along with their application in measurement of concentration, temperature and other combustion parameters. Related nonlinear techniques and recent extensions to the ultra-fast regime are briefly reviewed. Finally practical considerations relevant to multi-dimensional and multi-species measurements, as well as applications in technical combustion systems are discussed.Keywords: nonlinear optical spectroscopy, four-wave mixing, combustion diagnostics, minor species detection, laser-induced gratings, polarization spectroscopy IntroductionEnergy from renewable sources such as solar and wind power is the goal of much current research and technological development. Combustion, however, is and is likely to remain for the foreseeable future, the most important energy source for heat, electrical power and especially for transportation. In technical combustion systems the chemical energy of fossil fuels such as coal, crude oil and natural gas is converted into heat through oxidation with oxygen from air. However, fossil fuel resources are limited and alternatives like biofuels [1] or novel technologies such as fuel cells [2] are not yet able to meet the demand. Consequently, for a sustainable use of fossil fuels it is desirable to further improve the efficiency, maintainability and reliability of existing combustion devices. Achieving such improvements depends upon an improved understanding of t...

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Section: Molecular Physics Applicationsmentioning

confidence: 99%

Section: Analysis Of Dfwm Signals: Practical Considerationsmentioning

confidence: 99%

Section: Molecular Physics Applicationsmentioning

confidence: 99%

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Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Kiefer

Ewart

2011

Progress in Energy and Combustion Science

131

112

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“…2 DFWM can be independent of quenching rates, 19 but it loses sensitivity compared to ERE-CARS at increased pressure levels. 20 Similar to DFWM, PS can also be affected by collision rates. 12 Hence, ERE-CARS is a preferable technique at high pressure or when quenching is problematic.…”

mentioning

confidence: 99%

Perturbative theory and modeling of electronic-resonance-enhanced coherent anti-Stokes Raman scattering spectroscopy of nitric oxide

Kuehner

Naik

Kulatilaka

et al. 2008

The Journal of Chemical Physics

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for ERE-CARS NO spectra has been developed in the perturbative limit. Comparisons to experimental spectra are presented where either the probe laser was scanned with fixed Stokes frequency or the Stokes laser was scanned with fixed probe frequency. At atmospheric pressure and an NO concentration of 100 ppm, good agreement is found between theoretical and experimental spectral peak locations and relative intensities for both types of spectra.Factors relating to saturation in the experiments are discussed, including implications for the theoretical predictions.

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“…3,4 It has been shown that the technique is useful for atoms as well as for molecules like NO, 1 OH, 2 CH, 5 C 2 , 6 and NH 3 . 7 Like other coherent techniques as for example resonance enhanced coherent anti-Stokes Raman scattering ͑RECARS͒, 8 it combines high resolution with high sensitivity down to 10 9 particles per quantum state and cm 3 .…”

mentioning

confidence: 99%

Temperature determination of transient species by degenerate four wave mixing: Application of the independently determined power law of the transition dipole moment and geometric factors

Lehr

Motzkus

Pichler

et al. 1996

The Journal of Chemical Physics

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We investigated the dependence of the degenerate four wave mixing ͑DFWM͒ signal intensities on the electronic transition dipole moment of isolated lines in the A 1 ⌺ ϩ ←X 1 ⌺ ϩ transition band of NaH. We applied a new method to determine this dependence in transient species without previous knowledge of the sample temperature. By using different appropriate pairs of DFWM lines sharing common lower level, the relative population difference is eliminated. We found that this ratio is well described by a power law ( 1 / 2 ) x where i is the electronic one-photon transition dipole moment. As a result of saturation the exponent x depends on the total laser energy deposited in the medium. The observations are in good agreement with a modified two-level model, which includes the effects of polarization of the laser beams used in the experimental setup by introducing geometric factors. The exponent of the integrated signal intensities varies between 3 and 8 for high and low laser intensities with a rapid decrease to high intensities. This makes it possible to compare signal intensities at different DFWM laser intensities in order to obtain relative level populations, i.e., temperature, with high sensitivity.

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OH detection and spectroscopy by DFWM in flames; comparison with CARS

Cited by 34 publications

References 38 publications

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Laser diagnostics and minor species detection in combustion using resonant four-wave mixing

Perturbative theory and modeling of electronic-resonance-enhanced coherent anti-Stokes Raman scattering spectroscopy of nitric oxide

Temperature determination of transient species by degenerate four wave mixing: Application of the independently determined power law of the transition dipole moment and geometric factors

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