Photoionization of 1s Electron and Corresponding Shake-Up Process in Ground and Excited Lithium Atoms

The cross sections of the 1s electron photoionization and corresponding shake-up processes for Li atoms in the ground state 1s²2s and excited states 1s²2p, 1s²3s, 1s²3p and 1s²3d are calculated usin the multi-configuration Dirac--Fock method. The latest experimental photoelectron spectrum at h\ν=100eV Cubaynes D et al. Phys. Rev. Lett. 99(2007)213004 has been reproduced by the present theoretical investigation excellently. The relative intensity of the shake-up satellites shows that the effects of correlation and relaxation become more important for the higher excited states of the lithium atom, which are explained very well by the spatial overlap of the initial and final state wavefunctions. In addition, strong dependence of the cross section on the atomic orbitals of the valence electrons are found, especially near the threshold.