Electron- and Photon-Induced Fragmentation Dynamics in Simple Atoms and Molecules

Advanced imaging techniques such as COLTRIMS, coupled with high-resolution electron- and new X-ray photon sources, have triggered a new class of kinematically complete experiments that probe the details of electron- and nuclear dynamics in simple atoms and small molecules. The interpretation of these experiments presents a formidable challenge for contemporary theory, often involving fully differential cross section and excited-state reaction dynamics calculations that require precise, non-perturbative quantum mechanical methodology. I will illustrate this topic with several examples in which state-of-the-art {\em ab initio} theory can shed light on experiments which probe electron and/or nuclear fragmentation dynamics in simple systems. The examples will include sequential and non-sequential two-photon double ionization of helium, diffraction effects in high-energy photo-double ionization of H$_2$, core-hole localization in molecular nitrogen, inner-valence shell fragmentation of carbon monoxide and electron-induced three-body breakup of water.