Investigation Of The Wavepacket Motion Of Three-level Landder NaI Molecules In Intense Femtosecond Field

Photoelectric and dissociation of molecules in the strong field,has been more and more widely attention. Mainly because of the emergence of the femtosecond and attosecond and their ultra-fast super features. With the development of strong field technology, the dynamic properties of the molecule and the time evolution of the system are studied by using the intense laser pulse field, They may be realized and they are concerned by people. We studied the effect of laser parameters on the photoelectron spectra, wave packet motion and state populations of the threee-level ladder NaI molecules driven by intense femtosecond pump-probe pulses were investigated via employing the time-dependent wave packet approach in order to explore the condition and methods that wave packet motion and state populations transfer. The main contents are as follows:(1) We theoretically investigate the effect of delay time, laser wavelength and intensity on the photoelectron spectra and the wavepacket propagation of NaI molecule in the intense femtosecond pump-probe laser field via employing time-dependent wave packet approach. The photoelectron spectrum reflects the dynamic information of the wave packet. The nonadiabatic effects make the wave packet to split into two parts, wave packet of ground state arriving at outward turning point was the potential energy surface movement rebound back propagation, then returned to the crossing region happening again divided.Visible, increase with delay time, NaI molecular nonadiabatic effect is becoming more and more obvious. Delay time affects peak position and peak height. Pump wavelength affects the spectra profiles. Probe wavelength affects only peak position. The intensity affects only the peak height.(2) We theoretically investigate that delay time dependence of wave packet motion and photoelectron spectra and states populations of the three-level ladder NaI molecule is investigated by pump-probe pulses via time-dependent wave packet approach. Wave packet moves periodically with roundtrip time 1000 fs. The wave packet splits into two parts in the crossing region firstly at delay time 200 fs, the wave packet splitting affects state populations. We study the effects of delay time, pulse width,wavelength and intensity on the state populations in the next section. The results show that the excitation probability increases and dissociation probability decreases with increasing pulse width. The excitationprobability approaches the maximum with the resonance pump wavelength 318 nm. The dissociation probability decreases with increasing pump wavelength. As the pump intensity increases, the excitation probability increase while the dissociation probability does not change. The probe wavelength and probe intensity do not affect the state populations. The wave packet motion and selective distribution of state populations can be achieved by adjusting laser parameters.The results can provide some important basis for realizing the optical control and quantum manipulation of molecule experimentally.And provide some references for further studying the dynamics properties of atoms or molecules similar to NaI molecule.