VUV Photoionization Study Of Benzene/Oxygen And Butanol/Oxygen Flames

This dissertation is devoted to the VUV photonionization mass spectrometry study of benzene/oxygen and butanol/oxygen flames. The identification of most combustion intermediates observed in the benzene flame and four butanol flames are discussed. The flame structure and kinetic model of the benzene flame are also presented.In the first chapter, the development of the experimental and theoretical methods on combustion study, along with some basic concepts are briefly reviewed. The powerful combination of molecular beam mass spectrometry (MBMS) with photonionization by tunable vacuum ultraviolet (VUV) synchrotron offers significant improvements over previous facilities. These include superior signal-to-noise, soft ionization, and photon energies readily tunable for comprehensive flame species concentration measurements.In chapter 2, a detailed description on the flame endstation, the experimental procedures and the theoretical methods is presented. Especially, the structure and principles of both molecular beam and the reflectron time-of-flight (RTOF) mass spectrometer (MS) are described in detail.In chapter 3, the identification of most combustion intermediates observed in the benzene/oxygen flames are discussed. The isomers were identified in different ways. Whenever possible we compared observed photoionization efficiency curves with calculated and/or known ionization energies and known photoionization efficiency curves of pure substances. In addition, some other isomers were identified by comparing observed photoionization efficiency spectra with simulated photoionization efficiency curves based on Franck-Condon factor analysis. Some results are listed below:(1). Many unsaturated hydrocarbon radicals including C₃H₃, C₄H₃, C₄H₅, C₅H₃, and C₅H₅ were identified unambiguously for the first time. For C₄H₃, the stabilized CH₂CCCH isomer (i-C₄H₃) was presented in the flame; for C₄H₅, contributions from CH₂CHCCH₂ (i-C4H5) and some combination of the CH₃CCCH₂ and CH₂CHCCH isomers...