Research On The Dynamics Of Double-atom Molecules In The Strong Laser Field

Femtosecond science, based on the femtosecond laser, makes the research of molecular reaction dynamics to a new and higher level. The theory of quantum time-dependent wave packet that has been developed supplies a reason method for the research of the ionization-dissociation dynamics of the molecules. This method is based on BO approximation and the theory of interaction between molecule and laser field. It usually has the following steps: firstly, calculating the initio wave packet according the potential curve; secondly, translating the initio wave packet to the final time using the method of spliting-operator; and lastly, calculating the interesting objectives according to the last wave packet. Using this method, the paper mainly includes the following two works:1. The first chapter has calculated the photoelectron spectra of NO molecule in the process of 2+1'ionization by the pump-probe pulses. In the time-dependent wave-packet dynamics calculation, using the four-state model (the ground state of the NO molecule: X2Π, the two excited states of the NO molecule: A2Σ+ and B2Π, and the ground electronic state of the NO ion: X1Σ+) and the gauss function of the coupling between A2Σ+ and B2Π, it is showed in the figures that the change of the peaks of the photoelectron energy spectra as the change of the intensity of pump pulse. And the calculated result demonstrate the experimental results and hypothesis that the weak coupling between A2Σ+ and B2Πstates of NO plays a key role on the peak centered at 0.37 eV of the photoelectron spectra in the 2+1'channel. Then considering the time evolution of the population of A2Σ+ and B2Πwith the pump intensities, the coupling between A2Σ+ and B2Πis validated to exist.2. According the known potential curves of the ground state and excited state of CsI molecule, similar to the NaI, the second chapter has calculated the influence of the Stark pulse at different delay time to the two different dissociation channels of CsI. When the excited wave packet transmits to the diabatic coupling area, the delay time 720 fs, the modulation of the Stark pulse has the maximum effect on the two different channels. Using the LZ formula, the first order DSE gives a rational explanation to the calculated results. It has a guiding meaning that the Stark pulse is similar to the catalyst in the chemical reaction.In the finality, the problems requiring further studies are discussed...