O + CnH2n Products Detected via IR Emission. 1. O + C2H4
AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
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Collisions between oxygen atoms and ethene have been investigated by using infrared emission detection of the chemiluminescent product species. A prototypical alkene, ethene nonetheless exhibits numerous reaction pathways in reactions with O atoms. Oxygen atoms were formed via photolysis of SO2 in the presence of C2H4, and the resultant IR emissions in the 900-3000cm-1 spectral region were detected by using a time-resolved, step-scan Fourier transform spectrometer. A Welsh cell mirror arrangement was used to maximize the collection efficiency of the product IR emissions. Vibrationally excited products such as CO, CO2, HCO, and H2CO have been identified, with CO and CO2 being the dominant IR emitters. The time-evolving CO and CO2 spectra have been characterized with respect to the SO2 and C2H4 partial pressures and laser fluence. The rate constants for vibrational relaxation of CO2 high-nu population by CnH2n n 2-4 are in the mid 10exp -12 cu cm sexp -1 range SO2 is a very inefficient relaxer. A chemical kinetics code has been used to model the chemistry and identify the operative reaction mechanisms, including the effects of secondary chemistry.
- Organic Chemistry
- Infrared Detection and Detectors