Nanoparticle generation: the concept of a stagnation size region for condensation growth.

We demonstrate that the critical size cluster concept, commonly used in a nucleation theory, should be given some further attention. It has been implied that the supercritical cluster (size larger than critical) can grow via condensation. However, as we show, there is a size range, where the arrival of a vapor molecule onto a cluster surface leads to such a heating of the supercritical cluster that, due to possible evaporation, makes it unstable and, therefore, disables its condensation growth. The described phenomenon leads to substantial accumulation of certain size clusters in the system, which is clearly evident from our experimental investigation. The found suppression of the nucleus growth within the certain size range (exceeding critical) has fundamental implications for many systems where the generation of nanoparticles occur at high temperatures.