F. Chandezon et al., IONIZATION AND FRAGMENTATION OF METALLIC CLUSTERS (NA-N) INDUCED BY ION IMPACT, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 98(1-4), 1995, pp. 482-487
Neutral sodium clusters (Na-n, n less than or equal to 800) have been
ionized in collisions with different ion beams (H+, O5+, Ar8+) at coll
ision energies between 1 and 19 keV per charge. From an analysis of th
e measured mass/charge spectrum critical sizes for multiply charged cl
usters are deduced and compared with those obtained by laser-ionizatio
n. The dominant ionization mechanism depends on the charge state of th
e projectile. For highly charged ions the multi-electron capture proce
ss leads to the formation of relatively ''cold'' multiply charged clus
ters; in the proton case multiple ionization is discussed in terms of
electronic excitation followed by electron evaporation on a sub-nanose
cond time scale.