Luminescence from hydrogenfluorine flames, dilute in methane

✍ Scribed by C. Moore; M. Erickson; M. Kaufman

• Publisher: Elsevier Science
• Year: 1991
• Tongue: English
• Weight: 592 KB
• Volume: 87
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(91)90163-6

✦ Synopsis

Mechanisms producing luminescence from CH, C 2 , and CHF in CH4-F 2 flames are studied by the method of very dilute flames, whereby small amounts of CH,, (below 2%) are added to H2-F 2 flames. This technique allows the dependence of the emission intensities on the concentration of CH4 and carbon-containing radicals to be separated from its dependence on equivalence ratio and pressure, which determines flame temperature and the concentration of hydrogen and fluorine atoms. The most likely mechanism for C 2 emission is the reaction of two CH radicals, while CH emission (both A and B states) and CHF emission probably result from vibration-to-electronic (V-E) energy transfer from vibrationally excited HF. Experiments using CD 4 and O 2 are in agreement with the mechanism proposed for CH emission. The isotope experiments, as well as laser-induced fluorescence measurements on CH, indicate that the V-E energy transfer is by a single step, rather than by stepwise excitation up the vibrational ladder of CH(X). A diagnostics for the [F]/[F2] ratio in F2-H 2 or F2-hydrocarbon combustion is suggested. The mechanisms proposed for CH and C 2 luminescence are different from those generally discussed for the same emissions in oxygen-supported combustion.