The study of fundamental breakup processes in nature is important and paves the way for further investigation of the role of correlation in few- and multiphoton multiple ionization processes in atoms and molecules. The investigation of multiphoton double ionization processes by first principles is a relatively new research field stimulated by current progress in laser technology, and it is becoming increasingly clear that multi-electron effects play a decisive role.
The aim of our project is to pursue t hese investigations in the direction of more complex processes involving quasi-resonant excitation of autoionizing states (AIS) and/or doubly excited states. We will here focus on the processes of two-photon double ionization (TPDI) of Li and He. Prelimin ary studies of direct TPDI of He in initial excited states and Li reveal that this process is extremely rich in physics but difficult to calculate due to the presence of quasi-resonant excitation of AIS. Joining our expertise in TPDI and high performance numerical computations, our project is to tackle the problem of direct TPDI of asymmetric configurations for two- and three-active electron systems submitted to strong and short (fs) VUV fields.