CO VUV-Visible Emissions During Laser Photolyis of Ketene in the Presence of Excess O-atoms
Abstract
The interactions of carbonaceous combustion species in rocket plumes with the atmosphere are thought to play an important role in the production of ultraviolet, visible, and infrared radiation signatures at high altitudes. A detailed understanding of the pertinent chemical reactions that produce the electronically excited species, and of the competing quenching reactions that remove the internal energy in radiation-less processes is needed to accurately calculate short wavelength plume spectral signatures and absolute radiances and their temporal/spatial evolution in the high atmosphere. To facilitate these efforts, we are currently carrying out laboratory investigations to elucidate the reaction mechanism(s) in the oxidation of CH, CH2, C2H, and C2O with O-atoms and O2. Sufficient exothermicity in CH, CH2, and C2H reactions (except C2H + O) is available to produce CO in one or more of the triplet states (a, a', and d). Even more reaction enthalpy is available in C2O reaction(s) to produce higher excited states of CO (e, A, I, and D). Other excited species such as CH(A(exp 2) Delta) in C2H plus O or O2, and OH(A(exp 2)Sigma+) in CH + O2 reactions are also possible. CO-uv chemiluminescence has previously been identified in C2H + O2 reaction and both CO-uv and CO-vuv in the C2O + O reaction. However, no information is available on the product branching ratios of the excited CO states responsible for the emission. Estimates of the branching ratio of CH(A(exp 2)Delta) formation in the reactions of C2H with O and O2 can be found in the literature. To our knowledge, triplet CO formation in CH and CH2 reactions has not yet been positively identified. Fast discharge-flow tube and pulsed-laser photolysis methods have been employed in this work to study the reaction kinetics and chemiluminescence in these and C2O reactions. The experimental approach and results of these studies will be presented.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 14, 2001
- Accession Number
- ADA410494
Entities
People
- Ghanshyam L Vaghjiani