Ultrafast Photodissociation Dynamics Of Iodobenzene And Iodocyclohexane

The interactions between photons and matter are universal and sustained re-searches have been carried out to study how to use them for human's purpose.Af-ter absorbing photons,molecules become electronically excited and subsequently undergo many types of non-radiative deactivation processes,whose time scales in most cases are in picosecond or femtosecond.Femtosecond time-resolved mass spectroscopy has a time resolution in femtosecond and can be used to detect and trace the non-adiabatic dynamics of electronically excited molecules in real time.In this dissertation,as an important non-adiabatic dynamics,ultrafast photodis-sociation dynamics of iodobenzene and iodocyclohexane have been studied by femtosecond time-resolved mass spectroscopy.This dissertation mainly consists of the following parts.1.The deduction of the equations in lifetime fitting procedure.The deduction of the equations in lifetime fitting procedure has been pre-sented with detail and some phenomena in experiments have been explained with these equations.Also,the applications of fityk and gnuplot have been introduced in lifetime fitting procedure.2.The ultrafast photodissociation dynamics of iodobenzene in highly excited states upon photon excitation at 200 nm.With the aid of high-level,spin-orbit resolved ab initio calculations of one-dimensional potential energy curves,detailed photodissociation routes of iodobenzene upon photon excitation at 200 nm are discussed.Upon 200 nm excitation,7B2,7A1,7B1 and 8B2 states are possible doorway optical states.Iodobenzene molecules on 7B2 and 7B1 states decay to 7A1 and 8B2 states through internal conversion in 75 fs.7A1 and 8B2 states are excited with the high vibrational energy in the phenyl ring modes,and they decay through internal vibrational energy redistribution(IVR)before they dissociate,and the time for IVR is measured to be 540 fs.The rise time of 1.2 ps has been measured for the formation of I(2P3/2).3.The ultrafast photodissociation dynamics of iodocyclohexane within A-band and C-state.Iodocyclohexane was excited to the A-band by 266 nm excitation.The pho-todissociation dynamics within A-band is prompt,which involves conical intersection between 4A' and 4A".The time progression from the sub-sequent 4A" to the ground state iodine dissociation asymptotic region is around 180 fs.The photodissociation dynamics in the C-state has been studied by 200 nm excitation.The C-state has predissociative character with the predissociation time determined to be about 600 fs,which may have contributions from multiple vibrational modes.4.The commissioning and calibration of liquid microjet apparatus for photo-electron spectroscopy in liquid.The photoelectron spectroscopy in liquid based on liquid microjet has been presented with detail.The newly built liquid microjet apparatus has been debugged and calibrated and the applications and significance of this ap-paratus have also been reviewed and discussed.