Controlling the double photoionization dynamics of Li atoms by optical pumping

Double photoionization (DPI) of lithium atoms in a magneto-optical trap by 85 eV and 91 eV photons from the Hamburg Free Electron Laser (FLASH) is investigated using cold target recoil ion momentum spectroscopy. For ejection of a 1s and the optically excited 2p electron we demonstrate that the DPI cross section significantly depends on the alignment of the 2p valence orbital. Thus, the dynamical electron-electron correlation can be manipulated giving insight into the DPI mechanisms close to threshold.