Abstract
In the first chapter of this thesis, the photodissociation dynamics of benzene at 157, 193, and 248 nm have been investigated using photofragment translational spectroscopy (PTS) technique. The H atom, H2 molecule, CH3 elimination channels are the main research topics in the study. At 157 nm excitation, the experimental results show that H atom elimination comes from one dissociation channel, H2 molecule elimination comes from two distinctive dissociation channels, and CH3 elimination comes from one dissociation channel. The relative yields of these three channels is 1 : 0.07 : 0.2. From the photodissociation experimental results of benzene and its isotopomers(C6D6, 1,3,5-D3-C6H3D3, 1,4-D2-C6H4D2) show that the translational eneygy distribution of H/D elimination in various compounds are very close. In H2 elimination, there is much more different in the high energy part of the translational energy distribution which indicates that the two peaks in the translational energy come from two very different dissociation mechanisms. The relative yields of hydrogen atom(H/D) and hydrogen molecule(H2/HD/D2) elimination channels in benzene and its isotopomers were determined. It shows that the H atoms eliminate more than 2 times than the D atoms. From 1,3,5-D3C6H3D3，1,4-D2-C6H4D2 experimental results, the D2 elimination was detected. It identifies the hydrogen/deuterium atoms on the benzene ring have migration, and this migration(1,2-migration) can happen more than one time. Therefore, it shows some degree of the H/D scrambling on the benzene ring. At 193/248 nm study C6H6/C6D6 193 nm. At 193 nm, H atom elimination channel comes from one-photon absorption and H2 and CH3 elimination come from multiphoton absorption. At 248 nm, both H atom and H2 elimination come from multiphoton absorption. The second chapter is the dissociation lifetime measurements of benzene and some other organic molecule. At 193 nm excitation, the dissociation lifetimes of benzene and toluene are 8.9 and 3.3 μs respectively, while other molecules are about 3-4 μs. At 157 nm excitation, the dissociation lifetimes of benzene, benzene-d6, and toluene are 2.8, 3.4, 3.5 μs respectively. Besides the dissociation lifetime of cycloheptane is 12 μs, other molecules are about 2-3 μs. From the dissociation lifetimes of cyclopantane, cyclohexane, and cycloheptane, it shows an interesting trend that lifetimes become longer with the numbers in the ring of cycloalkanes increase.