Relaxation effects in electronically excited CH and C2 in low pressure hydrocarbon flames

1967 ◽  
Vol 45 (22) ◽  
pp. 2853-2855
Author(s):  
Rodney L. LeRoy
Keyword(s):  
Low Pressure ◽  
Hydrocarbon Flames ◽  
Relaxation Effects ◽  
Electronically Excited

Energy distribution in electronically excited CH and C2 in low pressure hydrocarbon flames

1967 ◽  
Vol 45 (20) ◽  
pp. 2441-2449 ◽  
Author(s):  
Gaspar Ndaalio ◽  
Jacques M. Deckers
Keyword(s):  
Energy Distribution ◽  
Cross Section ◽  
Vibrational Energy ◽  
Low Pressure ◽  
Rotational Energy ◽  
Gas Mixture ◽  
Hydrocarbon Flames ◽  
Quantum Numbers ◽  
Electronically Excited ◽  
Vibrational Energy Distribution

A study has been made of the rotational energy distribution of electronically excited CH and of the vibrational energy distribution of electronically excited C2 radicals in low pressure (0.2 to 35 Torr) hydrocarbon flames. The rotational energy of the CH radical in the A2Δ (ν = 0) state has been found to be statistically distributed in the levels with quantum numbers 14 to 21. This distribution can be described by a temperature which has, however, no thermodynamic significance. In the methane–oxygen flame this temperature has been found to be independent of both the composition of the gas mixture and the pressure, whereas in the ethylene–oxygen system it varies with these parameters. Hydrogen–methane–oxygen flames behave as ethylene flames. Inert diluents such as nitrogen and carbon dioxide do not affect the temperature at very low pressures. This indicates that the energy distribution is not perturbed measurably by collisions before emission takes place. In order to explain these observations we have to accept that at least two reactions produce CH* in ethylene flames.The cross section for energy transfer out of the high rotational levels of CH(A2Δ) to flame gases is found to be smaller than 0.6 Å2 and that for transfer to CO2 is about 2 Å2.A statistical distribution also has been observed in the vibrational energy distribution of electronically excited C2. The corresponding temperature is about 6 500 °K and is independent of the composition of the gas mixture and of the fuel. It decreases very slowly with increasing pressure above 3 Torr. Inert diluents added to the gas mixture do not alter this temperature.The cross section for de-excitation of C2(A3πg) is found to be smaller than 2.5 Å2.

Temperature measurement in fuel-rich non-sooting low-pressure hydrocarbon flames

2000 ◽  
Vol 70 (3) ◽  
pp. 435-445 ◽  
Author(s):  
A.T. Hartlieb ◽  
B. Atakan ◽  
K. Kohse-Höinghaus
Keyword(s):  
Temperature Measurement ◽  
Low Pressure ◽  
Hydrocarbon Flames

Photolysis of 2,5- and 2,4-Dimethylpyrrole Vapors at Room Temperature

1972 ◽  
Vol 50 (11) ◽  
pp. 1678-1689 ◽  
Author(s):  
E. Chung Wu ◽  
Julian Heicklen
Keyword(s):  
Excited State ◽  
Free Radical ◽  
Room Temperature ◽  
Low Pressure ◽  
Incident Radiation ◽  
Ring Cleavage ◽  
Incident Wavelength ◽  
First Order ◽  
Electronically Excited State ◽  
Electronically Excited

Both 2,5- and 2,4-dimethylpyrrole vapors at pressures from 0.05 to 0.70 Torr were irradiated at 2139 and 2288 Å at room temperature. The products were H2, CH4, C2H6, and polymer. No ring cleavage products were found. Φ{H2} and Φ{CH4} were remarkably insensitive to which pyrrole was used, its pressure,Ia, or the wavelength of the incident radiation. They were ~0.10–0.15 and ~0.01–0.02, respectively. Φ{C2H6} was comparable to Φ{CH4} and was also invariant to which substrate was used or the incident wavelength. However Φ{C2H6} did increase at low pressure or as Ia was reduced.The effect of scavengers showed that the products were produced mainly from free radical precursors. The main primary steps are:[Formula: see text]where DMP* is an electronically excited state of the dimethylpyrrole and Fa and Fb are radical fragments. Experiments with quenching gases showed that DMP* could be quenched, but that this reaction was less important than the first-order steps below 1 Torr.

Fullerene ions and their relation to PAH and soot in low-pressure hydrocarbon flames

1992 ◽  
Vol 96 (7) ◽  
pp. 841-857 ◽  
Author(s):  
Th. Baum ◽  
S. Löffler ◽  
Ph. Löffler ◽  
P. Weilmünster ◽  
K.-H. Homann
Keyword(s):  
Low Pressure ◽  
Hydrocarbon Flames

Time-resolved CH (A^2Δ and B^2∑^−) laser-induced fluorescence in low pressure hydrocarbon flames

1988 ◽  
Vol 27 (17) ◽  
pp. 3679 ◽  
Author(s):  
Karen J. Rensberger ◽  
Mark J. Dyer ◽  
Richard A. Copeland
Keyword(s):  
Low Pressure ◽  
Laser Induced Fluorescence ◽  
Time Resolved ◽  
Hydrocarbon Flames

A comprehensive experimental study of low-pressure premixed C3-oxygenated hydrocarbon flames with tunable synchrotron photoionization

2008 ◽  
Vol 152 (3) ◽  
pp. 336-359 ◽  
Author(s):  
Yuyang Li ◽  
Lixia Wei ◽  
Zhenyu Tian ◽  
Bin Yang ◽  
Jing Wang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Low Pressure ◽  
Hydrocarbon Flames
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