Energy transfer in the OH A<sup>2</sup>Σ<sup>+</sup>state: The role of polarization and of multi-quantum energy transfer

Brockhinke, Andreas; Lenhard, U.; Bülter, Andreas; Kohse‐Höinghaus, Katharina

doi:10.1039/b415637d

Cited by 10 publications

(8 citation statements)

References 42 publications

(72 reference statements)

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“…However, vibrational levels with v ≥ 3 (and higher rotational levels in v = 2) in the OH A-state are strongly influenced by pre-dissociation, which probably defines an upper limit of the states which are populated by the reactions. In rotational energy transfer, small steps are favored [6,34]. In either case, it takes more than just a few collisions to equilibrate such a huge imbalance.…”

Section: Oh * Chemiluminescencementioning

confidence: 96%

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Measurement and simulation of rotationally-resolved chemiluminescence spectra in flames

et al. 2012

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In recent years, there has been renewed interest in chemiluminescence, since it has been shown that these emissions can be used to determine flame parameters such as stoichiometry and heat release under some conditions. Even though the origin of these emissions has been known for a long time, little attention has been paid to the detailed analysis of the spectral structure.In this contribution, we present rotationally-resolved spectra of all important chemiluminescent emissions OH A-X, CH B-X, CH A-X, and C 2 d-a in CH 4 /air flames. A numerical model based on the LASKINν 2 code has been developed that allows, for the first time, to accurately predict the shape of the measured spectra for all of these transitions. Reabsorption of chemiluminescence within the emitting flame is shown to be a major factor, affecting both intensity and structure of OH * spectra. Even in lab-scale flames, it might change the intensity of individual lines by a factor of 5. The shape of chemiluminescence spectra depends on several processes including initial state distribution and rotational and vibrational energy transfer (which, in turn, depend on the collisional environment and the temperature). It is shown that chemical reactions form OH * in highly excited states and that the number of collisions is not sufficient to equilibrate the initial distribution. Therefore, high apparent temperatures are necessary to describe the shape of the measured spectra. In contrast, CH * is formed with less excess energy and the spectral shape is very close to thermal. The rotational structure of C * 2 is close to thermal equilibrium as well. Vibrational temperatures are, however, signif-A. Brockhinke ( ) · J. Krüger · M. Heusing · M. Letzgus icantly higher than the flame temperature. Implications and perspectives for flame measurements are discussed.

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Section: Oh * Chemiluminescencementioning

confidence: 96%

“…The role of collisional energy transfer in LIF has been studied extensively for several molecules and radicals relevant for combustion, including OH [4,6], CH [14], and C 2 [7]. We have developed a computer program, LASKINν 2 [40] that has proven to be capable of predicting the resulting fluorescence spectra with high reliability.…”

Section: Laskinν 2 Modelingmentioning

confidence: 99%

Measurement and simulation of rotationally-resolved chemiluminescence spectra in flames

et al. 2012

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“…Spectroscopic data for OH analysis are typically derived from Fourier transform spectroscopy [28,29] or by detailed studies of rotational spectra [30]. Fundamental data of OH molecular transitions are communicated in selected references [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]. Interrogations of ground-state or ground-level populations employ laser-induced fluorescence [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68] with practical applications to combustion diagnosis [69][70][71][72][73][74].…”

Section: Mini-summary Of Oh Literature and Applicationsmentioning

confidence: 99%

Laser-Plasma Spectroscopy of Hydroxyl with Applications

et al. 2020

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This article discusses laser-induced laboratory-air plasma measurements and analysis of hydroxyl (OH) ultraviolet spectra. The computations of the OH spectra utilize line strength data that were developed previously and that are now communicated for the first time. The line strengths have been utilized extensively in interpretation of recorded molecular emission spectra and have been well-tested in laser-induced fluorescence applications for the purpose of temperature inferences from recorded data. Moreover, new experiments with Q-switched laser pulses illustrate occurrence of molecular recombination spectra for time delays of the order of several dozen of microseconds after plasma initiation. The OH signals occur due to the natural humidity in laboratory air. Centrifugal stretching of the Franck-Condon factors and r-centroids are included in the process of determining the line strengths that are communicated as a Supplementary File. Laser spectroscopy applications of detailed OH computations include laser-induced plasma and combustion analyses, to name but two applications. This work also includes literature references that address various diagnosis applications.

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“…Spectroscopic data for OH analysis are typically derived from Fourier transform spectroscopy [20,21] or by detailed studies of rotational spectra [22]. Fundamental data of OH molecular transitions are communicated in selected References [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Interrogations of ground-state or ground-level populations employ laser-induced fluorescence with practical applications to combustion diagnosis [64][65][66][67][68][69][70][71].…”

Section: Mini Summary Of Oh Literaturementioning

confidence: 99%

Laser-Plasma Spectroscopy of Hydroxyl with Applications

Parigger¹,

Helstern²,

Jordan³

et al. 2020

Preprint

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This article discusses laser-induced laboratory-air plasma measurements and analysis of hydroxyl (OH) ultraviolet spectra. New experiments with Q-switched laser pulses illustrate occurrence of molecular recombination spectra for time delays of the order of several dozen of microseconds after plasma initiation. The computation of the emission spectra utilizes line strength data that are communicated as a supplementary file. Applications of detailed OH computations include laser-induced plasma and combustion analyses, to name but two applications.

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Energy transfer in the OH A²Σ⁺state: The role of polarization and of multi-quantum energy transfer

Cited by 10 publications

References 42 publications

Measurement and simulation of rotationally-resolved chemiluminescence spectra in flames

Measurement and simulation of rotationally-resolved chemiluminescence spectra in flames

Laser-Plasma Spectroscopy of Hydroxyl with Applications

Laser-Plasma Spectroscopy of Hydroxyl with Applications

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Energy transfer in the OH A2Σ+state: The role of polarization and of multi-quantum energy transfer

Cited by 10 publications

References 42 publications

Measurement and simulation of rotationally-resolved chemiluminescence spectra in flames

Measurement and simulation of rotationally-resolved chemiluminescence spectra in flames

Laser-Plasma Spectroscopy of Hydroxyl with Applications

Laser-Plasma Spectroscopy of Hydroxyl with Applications

Contact Info

Product

Resources

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Energy transfer in the OH A²Σ⁺state: The role of polarization and of multi-quantum energy transfer