Detection of atomic oxygen in flames by absorption spectroscopy

Cheskis, Sergey; Kovalenko, Sergey A.

doi:10.1007/bf01082398

Cited by 15 publications

(4 citation statements)

References 14 publications

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“…This can be accomplished, for instance, by recording the fully rotationally resolved structure of the band (i.e. by recording the emission intensity of the individual rotational lines of the band) and by fitting the intensities of the rotational lines to a "rotational Boltzmann factor" (Boltzmann plot [3,9,16]) from which one can obtain T R . As an alternative to recording fully rotationally resolved spectra, one can record the unresolved envelope of vibrational band with high statistical accuracy and then obtain T R from a "best-fit" of the envelope of the measured spectrum to a calculated band envelope, again with the rotational temperature as the only free parameter.…”

Section: Rotational Temperature Measurementsmentioning

confidence: 99%

Rotational and Vibrational Temperature Measurements in a High‐Pressure Cylindrical Dielectric Barrier Discharge (C‐DBD)

Masoud

Martus

Figus

et al. 2005

Contrib. Plasma Phys.

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The rotational (TR) and vibrational (Tv) temperatures of N2 molecules were measured in a high-pressure cylindrical dielectric barrier discharge (C-DBD) source in Ne with trace amounts (0.02 %) of N2 and dry air excited by radio-frequency (rf) power. Both TR and Tv of the N2 molecules in the C 3 Πu state were determined from an emission spectroscopic analysis the 2 nd positive system (C 3 Πu −→ B 3 Πg). Gas temperatures were inferred from the measured rotational temperatures. As a function of pressure, the rotational temperature is essentially constant at about 360 K in the range from 200 Torr to 600 Torr (at 30 W rf power) and increases slightly with increasing rf power at constant pressure. As one would expect, vibrational temperature measurements revealed significantly higher temperatures. The vibrational temperature decreases with pressure from 3030 K at 200 Torr to 2270 K at 600 Torr (at 30 W rf power). As a function of rf power, the vibrational temperature increases from 2520 K at 20 W to 2940 K at 60 W (at 400 Torr). Both TR and Tv also show a dependence on the excitation frequency at the two frequencies that we studied, 400 kHz and 13.56 MHz. Adding trace amounts of air instead of N2 to the Ne in the discharge resulted in higher TR and Tv values and in a different pressure dependence of the rotational and vibrational temperatures.

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Section: Rotational Temperature Measurementsmentioning

confidence: 99%

Rotational and Vibrational Temperature Measurements in a High‐Pressure Cylindrical Dielectric Barrier Discharge (C‐DBD)

Masoud

Martus

Figus

et al. 2005

Contrib. Plasma Phys.

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“…The conversion of relative fluorescence signals to absolute mole fraction is mostly performed through indirect approaches. Only Cheskis and Kovalenko [2] succeeded to quantify the O density in atmospheric H2/air flames by using the very sensitive Intra Cavity Laser Spectroscopy absorption technique applied on O-atom forbidden transitions at 630 and 636 nm.…”

Section: Introductionmentioning

confidence: 99%

Direct quantification of O-atom in low-pressure methane flames by using two-photon LIF

Lamoureux

Desgroux

2021

Proceedings of the Combustion Institute

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Quantification of the O-atom concentration is particularly important for testing the detailed kinetic mechanisms in flames. In this work, relative concentrations of O-atoms are measured by using the two-photon Laser-Induced Fluorescence method (TPLIF). The direct calibration for determining the absolute O-atom mole fraction is achieved by comparing alternately the integrated TPLIF signals from the atomic oxygen and from a known quantity of a noble gas (Xe). Both species have close spectral features with a two-photon absorption around 225 nm, while the fluorescence signals are collected around 844 and 834 nm for O-atom and Xe, respectively.Application of this method previously adopted in plasma environments is demonstrated here for the first time in low-pressure hydrocarbon flames. One major achievement in this work is that the O and Xe fluorescence signals are measured in the flame, thus allowing to properly correcting for the quenching rate of both species in this high temperature environment. Due to the fast quenching rates of O-atom and of Xe in the N2 diluted flames, a specific flame diluted in Ar was stabilized at 2.8 kPa for the calibration procedure. From Stern-Volmer plots obtained in a large pressure range of flames, the quenching rate determination could be extended to nitrogen-diluted flames. Then, the O-atom profiles were measured in absolute mole fraction in three lowpressure (5.3 kPa) premixed flames of CH4/O2/N2 with equivalence ratios equal to 0.8, 1.0 and 1.25. The experimental profiles O-atom mole fraction profiles are compared to the simulated ones. Their gradient locations and the absolute mole fractions at 25 mm are found in good agreement. However, the simulated profiles do not capture the experimental continuous decrease of O in the burnt gases.

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“…Since the laser beam in ICLAS has relatively low spectral width, low angular divergence, and high brightness, the use of an echelle spectrograph operating in high diffraction order with a narrow entrance slit allowing very high resolution is possible. ICLAS was realized with different types of lasers, 11,12 including dye lasers, 30–34 Ti:sapphire lasers, 35 and fiber lasers 36 …”

Section: Iclas Basicsmentioning

confidence: 99%

Intracavity Laser Absorption Spectroscopy for flame diagnostics

Rahinov

Gol'dman

Cheskis

2007

Israel Journal of Chemistry

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Intracavity Laser Absorption Spectroscopy (ICLAS) is one of the most sensitive techniques in absorption spectroscopy. Application of this technique to combustion diagnostics offers many important advantages. Since ICLAS is an absorption‐based method, it is not limited by the quenching and predissociation effects that compromise the sensitivity of Laser Induced Fluorescence (LIF), one of the most sensitive and widespread techniques applied in combustion diagnostics. For that reason, radicals that are subject to strong collisional quenching or predissociation, such as 1CH2 and HCO, can be measured by ICLAS with sensitivity much greater than that of LIF. For the same reason, ICLAS also possesses better sensitivity for NH and HNO. The present paper overviews the ICLAS measurements performed during the last decade in our laboratory and also presents recent results: first‐time detection of the HSO radical in flames by ICLAS and application of Fiber Laser Intracavity Absorption Spectroscopy (FLICAS) based on Er‐doped fiber laser for in‐situ detection of ammonia and hydrogen cyanide in a low‐pressure methane/air flame doped with a small amount of ammonia. Avenues for future research are discussed.

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Detection of atomic oxygen in flames by absorption spectroscopy

Cited by 15 publications

References 14 publications

Rotational and Vibrational Temperature Measurements in a High‐Pressure Cylindrical Dielectric Barrier Discharge (C‐DBD)

Rotational and Vibrational Temperature Measurements in a High‐Pressure Cylindrical Dielectric Barrier Discharge (C‐DBD)

Direct quantification of O-atom in low-pressure methane flames by using two-photon LIF

Intracavity Laser Absorption Spectroscopy for flame diagnostics

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