 The monomers are evaporated from the clusters with low thermal energies and they retain the center of mass velocity of the cluster and hence do not move out of the beam before colliding with the surface.When used to treat a surface, an ANAB beam has nearly the same total energy and velocity of the original GCIB beam but the smoothing effect on the surface is much different as the dispersed impacts of the individual fast atoms is more gentle than that of the clusters.With ANAB there is even less subsurface damage than with GCIB.