Controlling Vibrational Population Distribution Of Molecule By Ultrafast Laser Pulse

Light-matter interaction(LMI)is a very important and meaningful topic in the optical research.Controlling population transfer and distribution is basic and key research for LMI.The vibrational population distribution can be controlled by changing the laser parameters,exciting a superposition of different vibrational states,and achieving the preparation of the desired quantum state,which is beneficial to the vibrational spectroscopy,collision dynamics,energy redistribution and chemical reaction.The time-dependent Schr?dinger equation is computed to obtain the wave function using the time-quantum wave packet method in the paper.Controlling the vibrational population distribution in target state is mainly discussed by adjusting the pulse width,time delay,intensity and envelope of the pulses in the paper.In addition,the population transfer and influence of multiphoton ionization are studied,the population of multiphoton ionization is 0 within the range of 5×1012 W/cm2.The population transfer among the electronic states is theoretically investigated by the process of adiabatic passage by light induced potentials(APLIP).The variations of wave packet with time and coordinate are shown.Quantum control of the vibrational population distribution in the target state can be achieved by changing the pulse width,time delay,intensity and envelope of the pulses.The calculations show corresponding vibrational population distribution.The different vibrational population distribution is explained by the wave packet theory.With the increased pulse width,the bandwidth gets smaller,the motion of wave packet on the potential surface is changed,and the less vibrational states are excited.With the increased time delay and intensity,the coupling of the pulses between electronic states gets stronger,the distribution of wave packet on the light induced potentials are changed,and more vibrational states are populated.The effective area under peak intensity is changed by the envelopes,and evolution of wave packet on the potential surface is modified to control the vibrational population distribution.The preparation of the desired quantum state is achieved by controlling vibrational population distribution.