
36 Materials Processing by Cluster Ion Beams
are difcult to transport over long distances through simple
drift and acceleration tubes because divergence of the beams
is large compared with the situation of single- atom ion beams
at the same potentials. At the time it was also not clear that
the gas cluster ions would be strongly affected by collisions
with residual gas atoms, which cause the ions to lose energy
by fragmentation. These effects were observed and understood
over time and, after a decade, have become clearly explained
by experiments in recent investigations [41].
Researchers were especially interested in determining
whether GCIB ...