Experimental investigation of saturated degenerate four-wave mixing for quantitative concentration measurements

Reichardt, Thomas A.; Giancola, William C.; Shappert, Christopher M.; Lucht, Robert P.

doi:10.1364/ao.38.006951

Cited by 23 publications

(13 citation statements)

References 48 publications

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“…The asymmetric line shape of some of the detected IR-DFWM signals, like the one close to 2963.3 cm À1 is most likely due to mode-hopping during the scan of the multi-mode dye laser. It has been shown previously [22] that there are several advantages of using saturating laser energies for the DFWM signal. The collision dependence is less, the signal is less affected by absorption and laser power fluctuations and the pressure dependence is reduced.…”

Section: Measurements and Resultsmentioning

confidence: 99%

Non‐intrusive in situ detection of methyl chloride in hot gas flows using infrared degenerate four‐wave mixing

Sahlberg

Zhou

Aldén

et al. 2015

J Raman Spectroscopy

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We demonstrate the potential of infrared degenerate four-wave mixing (IR-DFWM) as a tool for non-intrusive in situ spatially resolved detection of CH 3 Cl in reactive hot gas flows especially feasible for applications to biomass combustion and gasification. IR-DFWM spectra of CH 3 Cl, by probing ro-vibrational transitions belonging to the fundamental stretching modes v 1 and v 4 , have been successfully recorded in gas flows diluted with nitrogen at atmospheric pressure and elevated temperatures up to 820 K. In order to identify the spectral lines of CH 3 Cl, the recorded IR-DFWM spectra are compared with simulations using molecular parameters extracted from the HITRAN database. The potential interference from water vapor is discussed from measurements of H 2 O spectrum at 820 K combined with simulations of H 2 O IR-DFWM spectrum based on the HITEMP database, and it was found that the Q Q 6 line of the v 1 band is relatively free from water interference at elevated temperatures. At atmospheric pressure, the detection limits for temperatures at 296, 550 and 820 K were estimated to be 2.1, 3.1 and 6.2 (×10 15 molecules/cm 3 ), respectively, by scanning the Q Q 6 line of the v 1 band. These results show the potential of interference free detection of CH 3 Cl with IR-DFWM in harsh environments like combustion.

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Section: Measurements and Resultsmentioning

confidence: 99%

Non‐intrusive in situ detection of methyl chloride in hot gas flows using infrared degenerate four‐wave mixing

Sahlberg

Zhou

Aldén

et al. 2015

J Raman Spectroscopy

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“…Absorption will reduce the intensity of the incoming pump and probe leading to reduced signal generation. The effects may be compensated partially by use of saturating laser power [48,81]. As a general rule it is advisable to use only optically thin media for quantitative measurements using DFWM.…”

Section: Theory Of Dfwmmentioning

confidence: 99%

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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“…1. Polarization spectroscopy (PS) line shapes and signal intensities were measured experimentally in well-characterized hydrogedair flames operated a wide range of equivalence ratios (Reichardt et al, 2000a). The PS apparatus is shown schematically in Fig.…”

Section: Theoretical and Experimental Investigation Of Polarization Smentioning

confidence: 99%

“…When the collisional linewidth is greater than the laser linewidth the resonant transition can respond to even the fastest fluctuations in the laser intensity, and the PS signal is enhanced by the multi-mode intensity spiking. I I~I I I , I , I~I I I , , , Our initial work in this area is discussed in detail in the proposal and in an article submitted to the Journal of Chemical Physics (Reichardt et al, 2000b).…”

Section: Multi-axial-mode Effects In Polarization Spectroscopymentioning

confidence: 99%

“…This study represents a major step forwards in terms of realistic modeling of DFWM as a diagnostic probe; so-called crossed polarization configurations are used commonly to reduce scattered light and to discriminate against thermal gratings. The theory of Williams et al (1994) applies in the perturbative regime but not in the saturation regime.…”

Section: Dni Calculation Of Polarization and Saturation Effects In Dfmentioning

confidence: 99%

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Final Report: Investigation of Saturated Degenerate Four-Wave Mixing Spectroscopy For Quantitative Concentration Measurements

Lucht¹

2001

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Principal Investigator: Robert P. Lucht (rlucht @ tamu.edu) Degenerate four-wave mixing (DFWM) and polarization spectroscopy (PS) are techniques that shows great promise for sensitive measurements of transient gas-phase species, and diagnostic applications of DFWM are being pursued actively at laboratories throughout the world. However, significant questions remain regarding strategies for quantitative concentration measurements using these techniques. The primary objective of this research program is to develop and test strategies for quantitative concentration measurements in flames and plasmas. Theoretically, we are investigating the physics of the PS and DFWM processes by direct numerical integration (DNI) of the time-dependent density matrix equations that describe the four-wave mixing interaction. Significantly fewer restrictive assumptions are required when the density matrix equations are solved using this DNI approach compared with the assumptions required to obtain analytical solutions. For example, the Zeeman structure of the resonance and effects such as Doppler broadening can be included, both the pump and probe beams can be saturating in the DNI calculations. As computer processing speeds have increased, we have incorporated more complicated physical models into our DNI codes.The incorporation of the Zeeman state structure of the laser-coupled energy levels has played a very significFnt role in our theoretical efforts over the last three years. For example, it has enabled us to develop theoretical models of the PS process. During the last three years of the grant we (1) developed a computer code for single-mode PS and investigated the effects of collisions and Doppler broadening , (2) investigated the effects of multi-axial-mode laser radiation on PS signal generation, (3) performed an extensive investigation of saturation effects in DFWM for different polarization configurations, (4) began a numerical study of picosecond PS. The incorporation of the Zeeman state structure in our DNI codes has given us a very powerful tool for the investigation of molecular spectroscopy, and much of our proposed future work is based upon this capability. Our diagnostic experiments are performed in wellcharacterized flames to assess the potential of the techniques for quantitative concentration measurements, and for meaningful comparison with our theoretical results.

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Experimental investigation of saturated degenerate four-wave mixing for quantitative concentration measurements

Cited by 23 publications

References 48 publications

Non‐intrusive in situ detection of methyl chloride in hot gas flows using infrared degenerate four‐wave mixing

Non‐intrusive in situ detection of methyl chloride in hot gas flows using infrared degenerate four‐wave mixing

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

Final Report: Investigation of Saturated Degenerate Four-Wave Mixing Spectroscopy For Quantitative Concentration Measurements

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