Nitric oxide concentration measurements in atmospheric pressure flames using electronic-resonance-enhanced coherent anti-Stokes Raman scattering

Chai, Ning; Kulatilaka, Waruna D.; Naik, Sameer V.; Laurendeau, Normand M.; Lucht, Robert P.; Kuehner, Joel P.; Roy, Sukesh; Katta, Viswanath R.; Gord, James R.

doi:10.1007/s00340-007-2647-1

Cited by 31 publications

(14 citation statements)

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“…The coherence was probed with a electronically resonant UV laser pulse at 236 nm. In a follow-up study a third flame environment -a hydrogen/air counter-flow flame, was investigated in which spatially resolved NO concentrations were measured in good agreement with numerical simulations [158]. These studies used a narrowband Stokes laser necessitating scanning of the laser frequency to obtain the NO spectra.…”

Section: Concentration Measurements and Thermometry Applicationsmentioning

confidence: 90%

“…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]. This approach has some advantages compared to the one with three lasers in As mentioned above the NO molecule has been extensively studied in recent years.…”

Section: Electronic Enhancement Of Cars Allows Detection Of Minor Spementioning

confidence: 99%

“…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]. This approach has some advantages compared to the one with three lasers in [161] studied collisional effects on the molecular dynamics and made a comparison with a previous investigation on quenching of NO in the presence of CO 2 , O 2 and N 2 [162].…”

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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: Concentration Measurements and Thermometry Applicationsmentioning

confidence: 90%

Section: Electronic Enhancement Of Cars Allows Detection Of Minor Spementioning

confidence: 99%

mentioning

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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“…͑3͒ The coherent nature of the signal beam is particularly advantageous in sooting environments. 3,5 ͑4͒ ERE-CARS is insensitive to drastic changes in the quenching ͑electronic energy transfer͒ environment 2 and exhibits favorable scaling with pressure. 4,6 Although experimental results demonstrated insensitivity of the signal to the electronic quenching rate of NO, the need exists to develop a more comprehensive predictive capability for the performance of ERE-CARS under varying collisional conditions.…”

Section: Introductionmentioning

confidence: 99%

Effects of collisions on electronic-resonance-enhanced coherent anti-Stokes Raman scattering of nitric oxide

Patnaik

Roy

Gord

et al. 2009

The Journal of Chemical Physics

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A six-level model is developed and used to study the effects of collisional energy transfer and dephasing on electronic-resonance-enhanced coherent anti-Stokes Raman scattering ͑ERE-CARS͒ in nitric oxide. The model includes the three levels that are coherently coupled by the three applied lasers as well as three additional bath levels that enable inclusion of the effects of electronic quenching and rotational energy transfer. The density-matrix equations that describe the evolution of the relevant populations and coherences are presented. The parametric dependencies of the ERE-CARS signal on collisional energy transfer and dephasing processes are described in terms of both a steady-state analytical solution and the numerical solutions to the governing equations. In the weak-field limit, the ERE-CARS signal scales inversely with the square of the dephasing rates for the electronic and Raman coherences. In accord with published experimental observations ͓Roy et al., Appl. Phys. Lett. 89, 104105 ͑2006͔͒, the ERE-CARS signal is shown to be insensitive to the collisional quenching rate. Parametric dependencies on quenching, rotational energy transfer, and pure electronic dephasing are presented, demonstrating reduced collisional dependence for saturating laser fields.

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“…This technique is capable of obtaining a few orders of magnitude enhancement of the CARS signal as compared to traditional CARS with a nonresonant probe [3][4][5]. Also, since the ERE-CARS technique is inherently quenching independent [6,7], this technique has been employed very successfully using nanosecond lasers for measuring the concentration of minor species such as NO [2,6,[8][9][10][11][12], which is a tracer pollutant in combustion processes [13]. However, since the resonant probe in the ERE-CARS configuration interacts strongly with the molecules, the saturation limit of the probe intensity is lower than that in conventional CARS [14].…”

Section: Introductionmentioning

confidence: 99%

Ultrafast saturation of electronic-resonance-enhanced coherent anti-Stokes Raman scattering and comparison for pulse durations in the nanosecond to femtosecond regime

2016

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The saturation threshold of a probe pulse in an ultrafast electronic-resonance-enhanced (ERE) coherent antiStokes Raman spectroscopy (CARS) configuration is calculated. We demonstrate that while the underdamping condition is a sufficient condition for saturation of ERE-CARS with the long-pulse excitations, a transient gain must be achieved to saturate the ERE-CARS signal for the ultrafast probe regime. We identify that the area under the probe pulse can be used as a definitive parameter to determine the criterion for a saturation threshold for ultrafast ERE-CARS. From a simplified analytical solution and a detailed numerical calculation based on densitymatrix equations, the saturation threshold of ERE-CARS is compared for a wide range of probe-pulse durations from the 10-ns to the 10-fs regime. The theory explains both qualitatively and quantitatively the saturation thresholds of resonant transitions and also gives a predictive capability for other pulse duration regimes. The presented criterion for the saturation threshold will be useful in establishing the design parameters for ultrafast ERE-CARS.

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Nitric oxide concentration measurements in atmospheric pressure flames using electronic-resonance-enhanced coherent anti-Stokes Raman scattering

Cited by 31 publications

References 27 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

Effects of collisions on electronic-resonance-enhanced coherent anti-Stokes Raman scattering of nitric oxide

Ultrafast saturation of electronic-resonance-enhanced coherent anti-Stokes Raman scattering and comparison for pulse durations in the nanosecond to femtosecond regime

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