Thin superconducting films with stoichiometric YBa2Cu3O7 composition a
nd low density of micro-particles have been deposited in situ by pulse
Nd: YAG laser (lambda = 1064 nm). The MgO(100) substrates were placed
behind a screen forming a shadow for ablated molecular fluxes. An ela
stic scattering model of the species ablated by background oxygen mole
cules has been carried out. Composition variation in the shadow region
is explained in terms of spatial separation of transverse Y, Ba and C
u fluxes.