  High intensity XUV radiation from a free-electron (FEL) was used to create a
nanoplasma inside ammonia clusters with the intent of studying the resulting
electron-ion interactions and their interplay with plasma evolution. In a
plasma-like state, electrons with kinetic energy lower than the local
collective Coulomb potential of the positive ionic core are trapped in the
cluster and take part in secondary processes (e.g. electron-impact
excitation/ionization and electron-ion recombination) which lead to subsequent
excited and neutral molecular fragmentation. Using a time-delayed UV laser, the
dynamics of the excited atomic and molecular states are probed from -0.1 ps to
18 ps. We identify three different phases of molecular fragmentation that are
clearly distinguished by the effect of the probe laser on the ionic and
electronic yield. We propose a simple model to rationalize our data and further
identify two separate channels leading to the formation of excited hydrogen.
