Collisional relaxation of singlet O2 in neat gas investigated by laser-induced grating technique

Hemmerling, B.; Kozlov,

doi:10.1016/s0301-0104(03)00226-x

Cited by 26 publications

(46 citation statements)

References 44 publications

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“…It was found that despite variations of the LIG signal profile and strength with pressure growth, the derived value of R practically does not depend on pressure in the range under investigation. This fact can be confirmed by speculations, similar to those presented by Hemmerling and Kozlov,50 assuming that the instantaneous energy exchange is the main reason of the thermal contribution. Thus, all the derived values can be described by the fitted exponential curve R D 1.29 š 0.04 exp 1.94 š 0.08 x , shown by the solid line in Fig.…”

Section: Calibration Measurementssupporting

confidence: 75%

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Local fuel concentration measurements for mixture formation diagnostics using diffraction by laser‐induced gratings in comparison to spontaneous Raman scattering

Kiefer¹,

Kozlov

Seeger³

et al. 2008

J Raman Spectroscopy

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The potential of the laser-induced gratings (LIGs) technique for the determination of fuel concentrations is investigated in comparison to the well-established spontaneous Raman scattering (SRS) technique. At pulse-repetitive excitation, the temporal shape of the LIG signals, containing non-resonant electrostrictive and resonant thermal contributions, as well as the Raman spectra were recorded in single-shot and accumulation modes. The measurements were performed in a laboratory system: in mixtures of propane as a fuel with nitrogen and air under stationary conditions in order to provide calibration data and to investigate the single-shot precision of measurements; and in the course of pulsed injection of gaseous propane into air at elevated pressures and temperatures. In the latter case, parameters of the experiment such as temperature, amount of injected gas and pressure were adjusted to be close to conditions of practical interest existing in real engines with direct injection (DI). The temporal variation of local propane concentration was tracked after the start of the injection pulse. Various approaches to the fast evaluation of the temporal shape of the measured LIG signals were tested, and their applicability in different ranges of propane concentrations, as well as single-shot measurement precision, were investigated. The results of employing the LIG technique were compared to those provided by the evaluation of the ratio of the integrated line intensities in the recorded SRS spectra.

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Section: Calibration Measurementssupporting

confidence: 75%

“…50, one can also show that the ratios of the thermal and electrostrictive contributions in nitrogen and air differ by only about 3%. Hence, to derive C 3 H 8 concentrations in propane/air mixtures during the injection experiments, the same calibration curve as that obtained for propane/nitrogen mixtures can be employed.…”

Section: Calibration Measurementsmentioning

confidence: 89%

Local fuel concentration measurements for mixture formation diagnostics using diffraction by laser‐induced gratings in comparison to spontaneous Raman scattering

Kiefer¹,

Kozlov

Seeger³

et al. 2008

J Raman Spectroscopy

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“…This was first demonstrated for gas phase studies by Hemmerling and co-workers [193,194] and the work of this group has been reviewed some years ago [195]. The detailed analysis of the internal relaxation channels in even the relatively simple case of a diatomic molecule such as O 2 proved to be a complex matter as outlined above [186]. Binary mixtures of O 2 and CO 2 have been studied by Hubschmid [196].…”

Section: Molecular Physics Applicationsmentioning

confidence: 95%

“…state following instantaneous excitation [186]. They considered a significant number of quenching mechanisms and channels in a complex analysis involving ~24 non-orthogonal variables related by non-trivial expressions.…”

Section: Analysis Of Ligs Signals Practical Considerationsmentioning

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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“…Typical transition strengths of the observed lines are of the order of ³10 24 cm 2 cm 1 /molecule. 23 In other studies, 24,25 LIGs formed as a result of the collisional relaxation of oxygen molecules excited via dipole-forbidden rovibronic transitions of the b 1  C g v 0 D 0 X 3  g v 00 D 0 band have been employed for recording absorption spectra of these transitions and measuring the line profiles at high resolution. The weak transitions, exhibiting line strengths of ³10 25 cm 2 cm 1 /molecule, 23 could be detected in a broad range of number densities between 0.2 and 160 Amagat.…”

Section: Introductionmentioning

confidence: 99%

Detection of vibrational overtone excitation in methane by laser‐induced grating spectroscopy

Kozlov

Radi

2008

J Raman Spectroscopy

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Laser-induced grating spectroscopy is applied to measure weak overtone and combination bands of methane between 11 170 and 11 980 cm −1 at pressures ranging from 0.2 to 4 bar and ambient temperature. The background-free method yields rotationally resolved spectra of transitions exhibiting cross-sections as low as ≈10 −26 cm 2 /molecule. The technique is suitable for clarifying the near-infrared spectra of planetary objects and to provide data for the development and verification of new models describing the complex energy structure of highly vibrationally excited molecules.

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Collisional relaxation of singlet O2 in neat gas investigated by laser-induced grating technique

Cited by 26 publications

References 44 publications

Local fuel concentration measurements for mixture formation diagnostics using diffraction by laser‐induced gratings in comparison to spontaneous Raman scattering

Local fuel concentration measurements for mixture formation diagnostics using diffraction by laser‐induced gratings in comparison to spontaneous Raman scattering

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

Detection of vibrational overtone excitation in methane by laser‐induced grating spectroscopy

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