  The condensation of zinc oxide nano clusters produced in gas phase has been
evidenced in the ablation of a ZnO solid target by a pulsed ArF laser. We
compare the spatio-temporal evolution of the shape of ZnO ablated plasma plume,
both in vacuum and in controlled gas environments (Helium and/or Oxygen) from
monitoring with CCD camera and from spectroscopic studies. The expansion of the
plasma plume and the growth of the nanoclusters depend strongly upon the
collisions between the ablated particles and surrounding gas molecules, as well
as on the chemical reactions in the case of oxygen. The spectra of the observed
plasma emittion are mainly due to atomic transitions in the neutral Zn. We have
also observed the photoluminescence of the nanoclusters suspended in the gas
and their decomposition in the beam of ArF laser.
