Core excitation in atomic and molecular clusters

Core level excitation, ionization, and fragmentation of homogeneous and heterogeneous atomic and molecular clusters is reported. Size and composition dependent properties of free clusters are derived. Total electron yields and partial cation yields are used for detection of spectroscopic changes as a function of cluster size. Photoionization of variable size and composition clusters is investigated by zero kinetic energy (ZEKE) photoelectron spectroscopy. Photoelectron-photoionphotoion- coincidence (PËPIPICO) spectroscopy is applied for determination of size dependent fragmentation mechanisms of doubly charged clusters. Argon and nitrogen are investigated as model systems. The results are compared to corresponding investigations of the isolated gas phase species and the condensed phase.