Formation of Triplet CO in Atomic Oxygen Flames of Acetylene and Carbon Suboxide

Abstract

Chemiluminescence spectra have been recorded for low-pressure, highly dilute, fuel-lean atomic oxygen flames of C 2 H 2 and C 3 O 2 ; under typical flame conditions the total pressure was 0.83 Torr with 1.1 mTorr of O atoms, 0.44 mTorr of O 2 , 0.20 mTorr of fuel, and the balance Ar. Spectral coverage was complete from 183 to 1500 nm for C 2 H 2 , and from 183 to 885 nm for C 3 O 2 . Strong CO a f X Cameron band emission was found to be the dominant feature of the chemiluminescence signature from 190 to 260 nm for C 2 H 2 oxidation under these conditions, with distinct but relatively minor CO A f X fourth positive emission between 185 and 195 nm. There is strong emission from higher triplet states of CO throughout the visible and near-IR, with CO e f a, d f a, and a′ f a emission features observed. Nearly identical CO emission spectra were obtained for both C 2 H 2 and C 3 O 2 fuels, which indicates that for both fuels the source of electronically excited CO is the C 2 O + O reaction. Quantification of emission yields for the four triplet electronic states of CO observed here indicates that little or no CO(a) is formed directly, rather its population results from radiative emission from higher triplet states. Approximately 70% of the triplet CO formed directly from the C 2 O + O reaction is in the a′ state, which had not been previously identified in this system.

CH(A2Δ) Formation in Hydrocarbon Combustion: The Temperature Dependence of the Rate Constant of the Reaction C2H + O2 → CH(A2Δ) + CO2

“…Most of these species have long been identified spectroscopically, CH(A 2 ∆, B 2 Σ -), C 2 -(d 3 Π g ), CN(B 2 Σ + ), HCO(Ã 2 A′′, B 2 A′), CO(a′ 3 Σ, d 3 ∆, e 3 Σ), and CO 2 (Ã 1 B 2 ), [1][2][3][4][5][6][7] and from their non-Boltzmann concentrations one must conclude their source to be either chemical reaction or rovibronic-to-rovibronic (E, υ, j f E′, υ′, j′) energy transfer. 8 However, finding the reactions responsible for their production and determining the associated rate constants have proven to be difficult challenges.…”

CO prompt emission as a CO2 marker in comets and planetary atmospheres

“…results yet. In the work of Burke et al [1996], the most intense band is the a´-a 2-0 band, 194 at 1.08 µ, which ought to be a target for cometary and planetary dayglow observations. 195…”

“…The spectra were calibrated utilizing 234 the phototube sensitivity and the monochromator grating efficiency, both to set the 235 photon fluxes on a comparable scale with respect to the two spectral regions, and to carry 236 out an extension into the IR. Because the phototube is not sensitive in the IR region, 237 where much of the triplet emission is found, we can use the calibrated IR spectrum 238 [Burke et al, 1996] to extend the spectrum. In this manner, we can evaluate how much of 239 the light is missing from the UV and visible region.…”

In Situ Infrared Emission Spectroscopy for Quantitative Gas-Phase Measurement under High Temperature Reaction Conditions: An Analytical Method for Methane by Means of an Innovative Small-Volume Flowing Cell

“…23 In particular, the various devices for infrared emission gas-phase analysis differ in the design of the heater needed to heat the gas phase and also in the design of the system used for collecting radiation emitted from the sample. The energy source can be a heater/furnace, 8,24 a laser for photolysis reactions, 19,25,26 or a gas burner for the detection of flame products and reaction intermediates. 25,[27][28][29][30][31] It is interesting to note that the typical sample chambers are fairly large: the emitted energy may be collected from chambers with a beam path of 40-60 cm 15,[32][33][34] or with a large volume (.50 mL).…”

“…The energy source can be a heater/furnace, 8,24 a laser for photolysis reactions, 19,25,26 or a gas burner for the detection of flame products and reaction intermediates. 25,[27][28][29][30][31] It is interesting to note that the typical sample chambers are fairly large: the emitted energy may be collected from chambers with a beam path of 40-60 cm 15,[32][33][34] or with a large volume (.50 mL). 35 In some cases, additional mirrors have been used to collect more of the emitted light in order to help improve the signal-to-noise ratio (S/N) and the sensitivity of the system.…”