The Study Of Wave Packet Dynamics Of Diatomic Molecules In Femtosecond Laser Field

The purpose of studying the mechanism of chemical reactions is to control the reaction process to get what is valuable for us. In the last two decades, femtosecond laser technics have obtained great development, and have been applied successfully to the study of molecular reaction dynamics and got lots of useful informations. On the other hand, theoretical studies also get great progresses. At present, there are many methods that are capable to deal with different systems. There are Molecular Mechanism method, Quantum Mechanism method, and Quantum Mechanism/Molecular Mechanism method. We study the time-depended quantum wave packet method in this thesis. Time-depended quantum wave packet method has became a major method of studying molecular reaction dynamics. The method starts with quantum machenics, then solve Schrodinger equations by using numerical methods, and finally get the whole picture of molecular motion on the potential surface.We studied photoionization and photodissociation dynamics of diatom molecule in femtosecond laser field, and calculated the photoionization and photodissociation dynamics of I2- ion, base on the pump-probe experimental results of I2- ion. We calculated the wave packet oscillation motion properties, and obtained the photoelectron spectrums within a long time range. Our energy peaks in the photoelectron spectrum are in good agreement with the experimental results, which prove that our method is reliable. We observed an oscillation character of the photoelectron spectrum that it oscillates with the delay time. By studying the photoelectron populations on different laser intensities, we found the nonlinear relationship between laser intensity and photoelectron population. By studying the electronic state populations under different laser intensities, we got the relationship between laser intensities and populations. As the intensity of laser increases, the Rabi oscillation was observed.The method we studied the I2- ion photoionization and the results we got provide a better understanding of the reaction dynamics process, and our results are valuable for small molecular photoionization and photodissociation experiments.