Quantitative measurements of the CH radical in sooting diffusion flames at atmospheric pressure

Understanding the ignition mechanism of high-pressure spray flames

“…12 for a fuel-rich ethylene-air premixed flat flame in which femtosecond two-beam phase matching was used to achieve single-shot images of spectra yielding temperature and relative concentrations of N 2 and O 2 in a sooting flame [284]. In situ measurements of OH [113,[285][286][287], CH [288], CH 2 O [289][290][291], and PAH [113,285,287,[291][292][293][294][295][296][297][298][299][300][301][302][303][304] distributions have been accomplished using laser-induced fluorescence (LIF) [113, 285-289, 291, 294-300, 302-304] or absorption spectroscopy [292][293][294]301]. Although characterization of the combustion environment is critically important for gaining insight into factors that influence soot evolution, a full review of available diagnostics for such supporting measurements is beyond the scope of the current review.…”

CH spectroscopic observables in He–CH4and N2–CH4atmospheric pressure dielectric barrier discharges

“…LIF measurements of CH density at atmospheric pressure have received a great deal of attention in combustion research. Almost all possible transitions involving the three electronic states A 2 , B 2 − and C 2 + have been employed to this end (see, for example, [6][7][8] and references therein). In spite of the difficulties due to the low emission yield of the excited states, particularly increased by the pre-dissociative character of B and C states, densities as low as 10 11 -10 12 cm −3 have been detected in atmospheric pressure flames [8], and even planar-LIF has been demonstrated in [9].…”

Influence of C2 and C3 compounds of natural gas on NO formation: an experimental study based on LIF/CRDS coupling

“…LIF measurements were performed by using a predissociated state of CH: the C 2 R + -X 2 P (0, 0) state near 315 nm, according to an excitation/detection scheme recently proposed in an atmospheric diffusion flame [13]. The use of a predissociated state leads to a weak fluorescence quantum yield A/(A + Q + P) but slightly dependent on quenching variations since the predissociation rate P is higher than the quenching rate Q at low pressure and higher than the spontaneous emission coefficient A.…”