原子分子是构成The free electron laser (FEL) at Hamburg (FLASH) (intensity, ~1012?1016 W/cm2; pulse duration, ~10?30 fs) in combination with a dedicated XUV-pump XUV-probe setup and our multi-particle detection system?the reaction microscope- will enable unique experiments on the XUV induced molecular fragmentations with femtosecond time resolution, a hitherto non-accessible regime of ultra-fast science. Here I start my talk with multiple ionization for atoms and expand toward time-resolved investigations of vibrational nuclear wave packets, dissociation-ionization, isomerization and elimination in small molecules. Present studies at FELs demonstrate the feasibility and the potential possibilities leading to remarkable breakthroughs for the study of atomic nonlinear absorption, molecular dynamics and chemical reactions in the XUV regime