Intracavity laser absorption spectroscopy of sooting acetylene/air flames

Gol'dman, A. Ya.; Cheskis, Sergey

doi:10.1007/s00340-008-3084-5

Cited by 20 publications

(14 citation statements)

References 30 publications

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“…In the interstellar medium dicarbon molecules have been detected in diffuse and translucent clouds, in the circumstellar shell of carbon stars, and in comets as well and they play an important role in the formation of hydrogen-deficient carbon molecules and the formation of cyclic molecules. 1,2 The intense d 3 g − a 3 u electronic transitions are used widely to detect the molecule in combustion [3][4][5][6][7][8][9][10][11] and astronomy [Ref. 12 and references therein] studies to characterize and test chemical mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Shedding light on a dark state: The energetically lowest quintet state of C$_2$2

Bornhauser

Sych

Knopp

et al. 2011

The Journal of Chemical Physics

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In this work we present a deperturbation study of the $d\,^3\Pi _g, v=6$d3Πg,v=6 state of C$_{2}$2 by double-resonant four-wave mixing spectroscopy. Accurate line positions of perturbed transitions are unambiguously assigned by intermediate level labeling. In addition, extra lines are accessible by taking advantage of the sensitivity and high dynamic range of the technique. These weak spectral features originate from nearby-lying dark states that gain transition strength through the perturbation process. The deperturbation analysis of the complex spectral region in the (6,5) and (6,4) bands of the Swan system ($d^3\Pi _g-a\,^3\Pi _u$d3Πg−a3Πu) unveils the presence of the energetically lowest high-spin state of C$_{2}$2 in the vicinity of the $d\,^3\Pi _g, v=6$d3Πg,v=6 state. The term energy curves of the three spin components of the d state cross the five terms of the $1\;^5\Pi _g$15Πg state at rotational quantum numbers N ⩽ 11. The spectral complexity for transitions to the v = 6 level of $d\,^3\Pi _g$d3Πg state is further enhanced by an additional perturbation at N = 19 and 21 owing to the $b\, ^3\Sigma _g^-, v=19$b3Σg−,v=19 state. The spectroscopic characterization of both dark states is accessible by the measurement of 122 “window” levels. A global fit of the positions to a conventional Hamiltonian for a linear diatomic molecule yields accurate molecular constants for the quintet and triplet perturber states for the first time. In addition, parameters for the spin-orbit and L-uncoupling interaction between the electronic levels are determined. The detailed deperturbation study unravels major issues of the so-called high-pressure bands of C$_{2}$2. The anomalous nonthermal emission initially observed by Fowler in 1910 [Mon. Not. R. Astron. Soc. 70, 484 (1910)] and later observed in numerous experimental environments are rationalized by taking into account “gateway” states, i.e., rotational levels of the $d\,^3\Pi _g, v=6$d3Πg,v=6 state that exhibit significant $^5\Pi _g$5Πg character through which all population flows from one electronic state to the other.

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Section: Introductionmentioning

confidence: 99%

Shedding light on a dark state: The energetically lowest quintet state of C$_2$2

Bornhauser

Sych

Knopp

et al. 2011

The Journal of Chemical Physics

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“…In particular for the application of non-linear optical methods such as degenerate and two-color resonant four-wave mixing, the computation of the correct spectral intensities is critically dependent on the relative positions of unresolved components because a coherent addition of overlapping transitions is required [19]. Furthermore, accurate molecular constants of the carbon dimer are needed in situations, where spectral features consist of multiple unresolved components [8,11]. In fact, this study has been motivated partially by our recent experiments on radicals in a free-jet emerging from discharged hydrocarbon/argon mixtures.…”

Section: Introductionmentioning

confidence: 99%

“…The strong d 3 P g À a 3 P u electronic system has been used to detect this minor species in combustion processes by applying numerous experimental techniques such as laser-induced fluorescence (LIF) [1][2][3], chemiluminescence [1], degenerate four-wave mixing (DFWM) [4,5], cavity ring-down (CRD) [2,6,7] and intracavity laser absorption spectroscopy (ICL) [8]. In addition, a recent experiment reports on the application of polarization spectroscopy of C 2 to visualize soot formation [9] and LIF for soot volume fraction measurements [10].…”

Section: Introductionmentioning

confidence: 99%

Deperturbation study of the state of C2 by applying degenerate and two-color resonant four-wave mixing

Bornhauser

Knopp

Gerber

et al. 2010

Journal of Molecular Spectroscopy

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“…An additional advantage of FLICAS is that it is insensitive to broadband losses, making it possible to work directly in harsh environments with strong broadband absorption or light scattering due to soot or other aerosol particles [22,25,26].…”

Section: Introductionmentioning

confidence: 99%

A fiber laser intracavity absorption spectroscopy (FLICAS) sensor for simultaneous measurement of CO and CO2 concentrations and temperature

Fomin

Zavlev

Rahinov

et al. 2015

Sensors and Actuators B: Chemical

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Intracavity laser absorption spectroscopy of sooting acetylene/air flames

Cited by 20 publications

References 30 publications

Shedding light on a dark state: The energetically lowest quintet state of C$_2$2

Shedding light on a dark state: The energetically lowest quintet state of C$_2$2

Deperturbation study of the state of C2 by applying degenerate and two-color resonant four-wave mixing

A fiber laser intracavity absorption spectroscopy (FLICAS) sensor for simultaneous measurement of CO and CO2 concentrations and temperature

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