Single-shot hyperspectral coherent Raman planar imaging in the range 0–4200 cm−1

Bohlin, Alexis; Kliewer, Christopher J.

doi:10.1063/1.4900477

Cited by 31 publications

(18 citation statements)

References 37 publications

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“…The present work additionally provides a quantitative assessment of single-shot species measurements (O 2 /N 2 ) in flames using femtosecond CARS. Previous work [17,35,48,49,34] has provided demonstration of species detection in low-temperature gas cells and furnaces with well-defined mixtures, or qualitative species imaging [50,51]. This study extends the technique to quantitative concentration monitoring in flame environments with simultaneous temperature measurement.…”

Section: Introductionmentioning

confidence: 87%

Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames

Kearney

2015

Combustion and Flame

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a b s t r a c tA hybrid fs/ps pure-rotational coherent anti-Stokes Raman scattering (CARS) scheme is systematically evaluated over a wide range of flame conditions in the product gases of two canonical flat-flame burners. Near-transform-limited, broadband femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is later probed using a high-energy, frequency-narrow picosecond beam generated by the second-harmonic bandwidth compression scheme that has recently been demonstrated for rotational CARS generation in H 2 /air flat flames. The measured spectra are free of collision effects and nonresonant background and can be obtained on a single-shot basis at 1 kHz. The technique is evaluated for temperature/oxygen measurements in near-adiabatic H 2 /air flames stabilized on the Hencken burner for equivalence ratios of u = 0.20-1.20. Thermometry is demonstrated in hydrocarbon/air products for u = 0.75-3.14 in premixed C 2 H 4 /air flat flames on the McKenna burner. Reliable spectral fitting is demonstrated for both shot-averaged and single-laser-shot data using a simple phenomenological model. Measurement accuracy is benchmarked by comparison to adiabatic-equilibrium calculations for the H 2 /air flames, and by comparison with nanosecond CARS measurements for the C 2 H 4 /air flames. Quantitative accuracy comparable to nanosecond rotational CARS measurements is observed, while the observed precision in both the temperature and oxygen data is extraordinarily high, exceeding nanosecond CARS, and on par with the best published thermometric precision by femtosecond vibrational CARS in flames, and rotational femtosecond CARS at low temperature. Threshold levels of signal-to-noise ratio to achieve 1-2% precision in temperature and O 2 /N 2 ratio are identified. The results show that pure-rotational fs/ps CARS is a robust and quantitative tool when applied across a wide range of flame conditions spanning lean H 2 /air combustion to fuel-rich sooting hydrocarbon flames.

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Section: Introductionmentioning

confidence: 87%

Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames

Kearney

2015

Combustion and Flame

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“…CARS techniques allow concentration and temperature measurements in harsh environments and at high temperature during the combustion process [16,17]. Moreover, one-dimensional [18,19], as well as two-dimensional [20] single-shot thermometry and mapping of reactants and products in gas flows can be performed by different experimental approaches. CARS signal is generated from the probe pulse scattering off the molecular vibration, coherently prepared by the pump (ωpump) and Stokes (ωStokes) pulses, which are resonant with the Raman frequency of the molecule (∆ωRaman).…”

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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“…The most common nonlinear vibrational spectroscopic approaches for detection of fuel molecules include coherent anti-Stokes Raman scattering (CARS) [142], infrared polarization spectroscopy (IRPS) [143,144] and degenerate four-wave mixing (IR-DFWM) [145,146], as well as laser-induced gratings (LIGs) [35,147,148]. The recent advances in the development of these techniques towards high-bandwidth measurements and multi-species detection will facilitate the characterization of multi-component fuels [149][150][151][152].…”

Section: Discussionmentioning

confidence: 99%

Recent Advances in the Characterization of Gaseous and Liquid Fuels by Vibrational Spectroscopy

Kiefer

2015

Energies

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Most commercial gaseous and liquid fuels are mixtures of multiple chemical compounds. In recent years, these mixtures became even more complicated when the suppliers started to admix biofuels into the petrochemical basic fuels. As the properties of such mixtures can vary with composition, there is a need for reliable analytical technologies in order to ensure stable operation of devices such as internal combustion engines and gas turbines. Vibrational spectroscopic methods have proved their suitability for fuel characterization. Moreover, they have the potential to overcome existing limitations of established technologies, because they are fast and accurate, and they do not require sampling; hence they can be deployed as inline sensors. This article reviews the recent advances of vibrational spectroscopy in terms of infrared absorption (IR) and Raman spectroscopy in the context of fuel characterization. The focus of the paper lies on gaseous and liquid fuels, which are dominant in the transportation sector and in the distributed generation of power. On top of an introduction to the physical principles and review of the literature, the techniques are critically discussed and compared with each other.

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Single-shot hyperspectral coherent Raman planar imaging in the range 0–4200 cm−1

Cited by 31 publications

References 37 publications

Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames

Hybrid fs/ps rotational CARS temperature and oxygen measurements in the product gases of canonical flat flames

Collinear FAST CARS for Chemical Mapping of Gases

Recent Advances in the Characterization of Gaseous and Liquid Fuels by Vibrational Spectroscopy

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