CORE EXCITATION IN ATOMIC AND MOLECULAR CLUSTERS

Core level excitation, ionization, and fragmentation of homogeneous an d heterogeneous atomic and molecular clusters is reported. Size and co mposition dependent properties of free clusters are derived. Total ele ctron yields and partial cation yields are used for detection of spect roscopic changes as a function of cluster size. Photoionization of var iable size and composition clusters is investigated by zero kinetic en ergy (ZEKE) photoelectron spectroscopy. Photoelectron-photoion-photoio n-coincidence (PEPIPICO) spectroscopy is applied for determination of size dependent fragmentation mechanisms of double charged clusters. Ar gon and nitrogen are investigated as model systems. The results are co mpared to corresponding investigations of the isolated gas phase speci es and the condensed phase.