Investigation Of Dynamic Stabilization Of Na Atom In An Intense Laser Pulse

In recent years,with the rapid development of laser technology,The interaction between light and matter is used as a means to explore the structure of microscopic substances and the laws of motion.Atoms and molecules in a strong laser field are ionized first.We know that in the weak field,the stronger the laser intensity,the greater the ionization rate of atoms or molecules.However,the theorists predict that ionization suppression of atoms(or molecules)may occur when the laser intensity continues to increase.In this paper,the alkali metal atoms are selected as the target atom and the initial wave function is used in different states,The laser field drives the target atoms and disassociates them,calculating the ionization probability and time-dependent population distributions of the valence electrons for different values of principal quantum number n and orbital quantum number.Research results show that,When the laser wavelength is between 200 and 600nm,the initial state of Na atom is in the 4s excited state,and the ionization chauracteristic of the evolution wave function which projected on the bound state is that as the intensity of the laser field increases,the ionization takes the first step,then decreases and then increases.By analyzing the population distributions of the valence electrons.When the ionization probability of Na atom decreases with the intensity of the laser field,the number of the electrons in the ground state or low excited state is large,while the number of high excited states is almost zero.This indicates that the electrons oscillate rapidly between the bound state and the continuous state with the strong laser field,that to say the atom has a stable area in the strong laser field.The specific content is as follows:The time-dependent Schrodinger equation of sodium atom in the intense laser field is solved by using the splitting operator technique of pseudospectrum.The bound state energy levels in the exact model are calculated.The results are in good agreement with the experimental results.So it is possible to calculate the ionization characteristics of sodium atoms in the intense laser field.Secondly,the initial wave function of Na atom excited state 3s,3p and 4s was selected respectively.The relationship between the power probability of the atom and the peak intensity of laser is calculated when the wavelength is 400nm.The study shows that all ionization probability increase as the laser intensity increases and then decreases.If the initial states of the Na atom is 3s or 3p,The stable window exists at a higher laser intensity,approximately 1.0 × 1016 W/cm2.However,if the initial state is in 4s,The stable window is in the lower laser field 2.6 x 1015 W/cm2.The current femtosecond laser can observe such a result.Finally,we selected the 4s as the initial state,and the laser wavelength was 200nm,300nm,400nm and 600nm respectively.and calculated the change of the atomic ionization probability with the laser intensity.