Gas Concentration Measurement by Coherent Raman Anti-Stokes Scattering

Regnier, P.; Moya, Francisca; Taran, J. P.

doi:10.2514/3.49358

Cited by 94 publications

(6 citation statements)

References 21 publications

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“…Both spontaneous and coherent Raman scattering effects have been employed in spectroscopic systems applied to trace detection and identification of chemicals [1,2] and as a method to measure concentrations of various components in gases [3][4][5], liquids and solids [6,7]. In spontaneous Raman scattering, the signal is directly proportional to the number of molecules interacting with a single beam of input light.…”

Section: Introductionmentioning

confidence: 99%

Collinear FAST CARS for Chemical Mapping of Gases

et al. 2017

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Featured Application: remote spectroscopic mapping of gas emissions and leaks. Abstract:We examine the concentration dependence of the Coherent Anti-Stokes Raman Scattering (CARS) signal obtained for gas mixtures at various conditions using the Femtosecond Adaptive Spectroscopic Technique (FAST). We use the CARS signal of the Q-branch vibrational oscillation of molecular oxygen (1556 cm −1 ) to confirm the quadratic dependence of the coherent signal on the number of molecules in a test volume. In addition, we demonstrate multi-shot FAST CARS imaging of a gas flow in free space by raster-scanning the area of interest.

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Section: Introductionmentioning

confidence: 99%

Collinear FAST CARS for Chemical Mapping of Gases

et al. 2017

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“…The quantity l c is the interaction length of waves o 1 and o 2 depending on the focusing conditions and the dispersion of the medium. At reduced pressures, focusing of coaxial beams by lenses with a focal length of 10±100 cm provides local measurements with a transverse dimension of $ 0X1 mm and a length of $ 1À10 mm [106]. An additional limitation of the localization length is achieved by crossing beams o 1 , o 2 at small ($ 0X1 rad) specially chosen angles without violating condition (41) according to the BOXCARS, FOLDRD BOXCARS method [103,107].…”

Section: Four-wave Processesmentioning

confidence: 99%

Spectroscopy of small gas components of a nonequilibrium low-temperature plasma

Очкин

2021

Phys. Usp.

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The state of the art and prospects for the development of quantitative optical spectroscopy methods for analyzing the composition of small chemically active components of a nonequilibrium plasma are discussed. The capabilities of the methods are considered in combination with the conditions of applicability, both for fundamental research in the fields of plasma physics and chemistry, and for monitoring the technological processes in reactors for the benefit of the energy sector, micro-and nano-electronics, medicine, the creation of optical coatings, and generating active radicals and excited particles.

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“…This process is a two photon process that occurs simultaneously with the CARS process and reduces the population difference between the ground and the excited state. The rate of change of population difference (slump rate) for monochromatic beams can be approximated by:

\frac{1}{Δ N} \frac{\partial Δ N}{\partial t} = 2 {((), \frac{4 π c}{ℏ ω_{normalS}^{2}})}^{2} (\frac{\partial σ}{\partial Ω}) \frac{Γ_{R}}{4 {((), Δ ω)}^{2} + Γ_{normalR}^{2}} I_{normalp} I_{normalS} = τ_{normalΔN}^{- 1}

…”

Section: Stimulated Raman Pumpingmentioning

confidence: 99%

Saturation and Stark broadening effects in dual‐pump CARS of N₂, O₂, and H₂

Magnotti

Cutler

Herring

et al. 2012

J Raman Spectroscopy

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The dual-pump coherent anti-Stokes Raman spectroscopy (CARS) technique is frequently employed in the study of turbulent flames, but the applicability of this technique is limited by low signal-to-noise ratios at high temperatures. The signal-to-noise ratio can be increased by increasing the energy of the lasers. Unfortunately, there is a limit to the amount of energy that can be added before the signal is affected by high irradiance perturbation effects such as Stark broadening and stimulated Raman pumping (saturation). Such effects alter the spectral shape of the CARS signal and compromise the measurement accuracy. To explore these effects, dual-pump CARS spectra containing the N 2 and O 2 Q-branch manifolds and three S-branch H 2 rotational lines were acquired in H 2 -air flames while varying the irradiances of the different input beams. For fuel-lean flames at 1180 K and 1 atm., absolute mole fraction measurements are affected by Stark broadening when the total irradiance is above 250 GW/cm 2 , and by saturation when the product of the pump and Stokes irradiances is above 2 Â 10 3 GW 2 /cm 4 . The H 2 S-branch is more sensitive to Stark broadening, and small variations in the line amplitude are observed for total irradiance of 170 GW/cm 2 . Temperature measurements are not sensitive to Stark broadening, but they are affected by saturation when the pump-Stokes irradiances product is above 2 Â 10 4 GW 2 /cm 4 .

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Gas Concentration Measurement by Coherent Raman Anti-Stokes Scattering

Cited by 94 publications

References 21 publications

Collinear FAST CARS for Chemical Mapping of Gases

Collinear FAST CARS for Chemical Mapping of Gases

Spectroscopy of small gas components of a nonequilibrium low-temperature plasma

Saturation and Stark broadening effects in dual‐pump CARS of N₂, O₂, and H₂

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Gas Concentration Measurement by Coherent Raman Anti-Stokes Scattering

Cited by 94 publications

References 21 publications

Collinear FAST CARS for Chemical Mapping of Gases

Collinear FAST CARS for Chemical Mapping of Gases

Spectroscopy of small gas components of a nonequilibrium low-temperature plasma

Saturation and Stark broadening effects in dual‐pump CARS of N2, O2, and H2

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Saturation and Stark broadening effects in dual‐pump CARS of N₂, O₂, and H₂