The influence of laser pulse on the photoabsorption spectra of Li atom in strong external field

Using the time-dependent perturbation theory and the calculation formula of the single-and double-pulse absorption spectra of the atom in strong external fields, we calculate the single-and double-pulse absorption spectra of Li atom in strong magnetic field for different pulse widths. The results show that a pulse of some width can reduce the contribution of the short period closed orbits and eliminate the contribution of the long period orbits. Compared with the single-pulse absorption spectra, we found that for some phase differences, the double-pulse laser absorption spectra are strengthened; while for others, they are reduced. Therefore, we can use the pulse laser to control the oscillation of the absorption spectra and obtain the optimization object.