Time-, wavelength-, and polarization-resolved measurements of OH (A 2Σ+ ) picosecond laser-induced fluorescence in atmospheric- pressure flames

Brockhinke, Andreas; Kreutner, W.; Rahmann, Ulrich; Kohse‐Höinghaus, Katharina; Settersten, Thomas B.; Linne, Mark

doi:10.1007/s003400050838

Cited by 20 publications

(12 citation statements)

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“…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]. However, diagnosis applications are based on extensive studies of the ultraviolet OH system [75][76][77][78][79]…”

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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Section: Mini-summary Of Oh Literature and Applicationsmentioning

confidence: 99%

Laser-Plasma Spectroscopy of Hydroxyl with Applications

et al. 2020

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“…The following example illustrates this strategy. If one detects the spectrally resolved ultraviolet laserinduced fluorescence (LIF) from OH in an atmospheric flame (lifetime of ;1 ns) 11 with a resolution on the picosecond time scale, 12 one would seek to make the time scale of the optical beating (much) longer than the fluorescence lifetime. If the spectral resolution of the detection system, e.g., a monochromator, 12 is much better than 1 GHz (0.03 cm À1 ), the distortion of the fluorescence decay trace due to the optical beating will be negligible, since the beating time scale will be longer than 1/(1 GHz) ¼ 1 ns, i.e., longer than the LIF signal itself.…”

Section: Means To Circumnavigate or Mitigate Interferencementioning

confidence: 99%

Optical Beating of Polychromatic Light and its Impact on Time-Resolved Spectroscopy. Part II: Strategies for Spectroscopic Sensing in the Presence of Optical Beating

2008

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Time-resolved spectroscopy can be compromised by optical beating, which is inherent to polychromatic light sources and signals. For incoherent light sources, the random interference can partially or completely mask the spectroscopic signature of interest if the time dynamics of the interference are similar to or faster than that of the signature. Part I of this review focused on the theory of this process with an emphasis on thermal light sources, and in this part, four methods to mitigate or circumnavigate the detrimental impact of interference on time-resolved spectroscopy are reviewed: use of light with a controlled, non-stochastic phase, use of narrow-bandwidth light, averaging, and pulse referencing.

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“…The v = 2 levels are predissociative and the radiative lifetime of N = 9 into which the excitation leads is shortened from ∼ 871 ns to approximately 30 ns [13]. With quenching lifetimes for A-state levels on the order of 1-2 ns [17][18][19] and rotational and vibrational energy transfer rates [18,20,21] high enough to allow some redistribution of the original excited-state population a substantial fraction of the excited molecules radiate from levels other than N = 9. So, while a prominent portion of the emission spectrum is given by transitions starting from N = 9 (P 1 (10), Q 1 (9) and R 1 (8)) for the (2,0), (2,1) and (2,2) bands, more rotational scrambling is observed for transitions that originate from v = 1 and v = 0 since the rotational quantum number is not preserved during vibrational energy transfer.…”

Section: R E S U L T Smentioning

confidence: 99%

Single-shot imaging of OH radicals and simultaneous OH radical/acetone imaging with a tunable Nd : YAG laser

Sick

Wermuth

2004

Appl Phys B

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Single shot imaging capability for OH radical distributions in various atmospheric pressure methane flames upon excitation with a tunable frequencyquadrupled Nd : YAG laser is demonstrated. The laser wavelength can be tuned with an intra-cavity etalon to produce laser-induced fluorescence (LIF) signals from OH via absorption in the OH AX (2,0) P 1 (10) line. Simultaneous single-shot imaging of the burnt and unburnt zones in laminar nonpremixed, premixed and turbulent flames is presented. The unburnt areas are visualized with LIF of acetone that is seeded to the methane fuel. Acetone levels are set to match signal intensities to that of the OH signals to allow imaging on a single intensified CCD camera.

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Time-, wavelength-, and polarization-resolved measurements of OH (A 2Σ+ ) picosecond laser-induced fluorescence in atmospheric- pressure flames

Cited by 20 publications

References 0 publications

Laser-Plasma Spectroscopy of Hydroxyl with Applications

Laser-Plasma Spectroscopy of Hydroxyl with Applications

Optical Beating of Polychromatic Light and its Impact on Time-Resolved Spectroscopy. Part II: Strategies for Spectroscopic Sensing in the Presence of Optical Beating

Single-shot imaging of OH radicals and simultaneous OH radical/acetone imaging with a tunable Nd : YAG laser

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