Studies On Photoionization And Photodissociation Of Halides Containing Compounds

Photoionization and photodissociation are the two main product channels following the interaction of the molecules with laser. Study of photoionization and photodissociation can help us to obtain the information of the ionic states and excitedstates of the molecules and open a window to know the essence of chemical reaction. Mass Analyzed Threshold Ionization (MATI) Spectroscopy is a powerful technique for studies of molecular ions and offers a very high resolution. MATI has become one of the major methods for obtaining information about the ionic states of the molecules as well as radicals, complexes and clusters. The molecular photodissociationdynamics is a very important part of molecular reaction dynamics. The ion velocity map imaging technique is an ideal experimental method for investigating the photodissociation dynamics. It can simultaneously give the correlated quantities and rich dynamic information. In this dissertation, MATI and velocity map imaging techniques have been applied to study the ionic states and photodissociation dynamics of several molecules, respectively.This dissertation is composed of three parts:The first part is the investigation on two-color two-photon MATI spectra of methyl-indoles and one-color two-photon MATI spectra of iso-bromopropane. The accurate adiabatic ionization energies of 4-methylindole, 7-methylindole and iso-bromopropane are determined. The vibrations in the spectra have been assigned combining with our ab initio and density function theory calculations. The substitution effect on the excited energies and ionization potential values has been discussed.The second part is the study of ultraviolet photodissociation dynamics of 1, 2-dibromoethane, tert-butyl bromide and iso-butyl bromide using velocity map imaging method. We have measured the translational energy and the angular distributions of the fragments. The C-Br bond fission dynamics in the ultraviolet photodissociation has been analyzed. The effect of coupling between the potential energy surfaces on the product channels has been discussed.The third part is focused on the dissociative ionization and Coulomb explosion of ICl and CH3I induced by femtosecond laser using velocity map imaging. We have measured the velocity and angular distributions of the ionic products. The possibleproduct channels in the dissociative ionization and the alignment mechanism in the Coulomb explosion process have been discussed.