Аннотация:There are number of methods to detect formation of nanoclusters produced by ns-laser ablation, during the expansion of vapor: optical time of flight (TOF), photoluminescence, Rayleigh scattering, etc. For typical conditions of expansion into the vacuum, formation of nanoclusters is completed at the moment of quenching (when the collisions are terminated) which occur after a few microsecond(s) . During the expansion of vapor into the background gas, the condensation process is terminated due to mixing of vapor with background gas. The characteristic mixing time can be estimate from the characteristic increment of the Rayleigh-Taylor instability; this time is around a few microsecond(s) for typical pressures of background gas. Fast formation of overcritical clusters is confirmed by TOF experiments.