UV Photodissociation Dynamics of Polyatomic Free Radicals Using High-n Rydberg Atom Time of Flight Spectroscopy

The ultraviolet (UV) photodissociation dynamics of several free radicals were studied using High-n Rydberg H-atom time-of-flight (HRTOF) spectroscopy, including the nitrogen contain aromatic radicals o-pyridyl and m-pyridyl, cyclohexyl which is a cyclic alkyl radical, and four isomers of the unsaturated C4H7 radical system. The four isomer studied where 1-methylallyl, 2-methylallyl, 2-buten-2-yl, and 2-methyl-1-propenyl radicals. The vacuum ultraviolet (VUV) photodissociation dynamics of methanol was also studied.;The first chapter discusses photodissociation dynamics as well as the experimental methodology. The HRTOF experimental technique used in this research is explained in detail.;The second chapter investigates the UV photodissociation of o-pyridyl radicals in the region of 224-246 nm. The H-atom product translational energy release indicates the production of cyanovinylacetylene + H. The H-atom product yield spectrum, product angular distribution and photodissociation mechanism were also obtained.;Chapter 3 investigates the UV photodissociation of m-pyridyl radicals in the region of 224-246 nm. The H-atom product translational energy release distribution indicates the production of cyanovinylacetylene + H. The H-atom product yield spectrum, product angular distribution and photodissociation mechanism were also obtained.;Chapter 4 investigates the UV photodissociation of cyclohexyl radicals in the region of 232-262 nm. The H-atom photofragment yield spectrum is in good agreement with previously reported UV absorption spectra. The production translation energy release distribution indicates a non-statistical photodissociation process to produce cyclohexene + H. The product angular distribution showed an anisotropic distribution. The photodissociation mechanism was obtained.;Chapter 5 investigates the UV photodissociation of the 1-methylallyl, 2-methylallyl, 2-buten-2-yl, and 2-methyl-1-propenyl radicals. The H-atom time-of-flight spectra of three of the four C4H7 radicals showed a bimodal feature indicating two photodissociation mechanisms while the 2-methyl-1-propenyl radical showed a single feature. All of the isomers showed a statistical H-atom product channel while 1-methylallyl, 2-methylallyl, and 2-buten-2-yl also showed a non-statistical photodissociation H-atom product channel. The H + C4H6 product translational energy distributions and the photodissociation mechanism were obtain for each of the radicals.;Chapter 6 discusses the VUV photodissociation of CH3OH and CH3OD at 121.6 nm. The H-atom product TOF spectrum of CH3 OH and D-atom spectrum have a bimodal distribution. The photodissociation mechanisms and branching ratios were obtained.;Chapter 7 will briefly discuss the results of a related system, 3-cyclohexenyl radical, and general conclusions.