Multiply charged cluster ion crossed-beam apparatus: Multi-ionization of clusters by ion impact

An experimental setup is described, which is used to multi-ionize neutral c lusters and to study their stability and the importance of different decay processes. Clusters are ionized in collisions with slow multiply charged io ns (projectile charge z ranging from 1 to 30, kinetic energies ranging from 1 to 20 keV/charge). Both ion and cluster beamlines, as well as the charac teristics of the analysis and detection systems, are described. Collisions with highly charged ions such as Ar8+ or Xe30+ turn out to be efficient too ls in preparing clusters in high charge states without increasing significa ntly their internal temperature. Measurements performed in coincidence with the number of electrons stabilized by the projectile ion after the collisi on allowed us to control the charge and the excitation energy of the ionize d system. The efficiency of the method is demonstrated for sodium clusters and C-60 molecules. (C) 1999 American Institute of Physics. [S0034-6748(99) 04708-5].