We investigated the nucleation process at the molecular level. Controlled sticking of individual atoms onto mass selected clusters over a wide mass range has been carried out for the first time. We measured the absolute unimolecular nucleation cross sections of cationic sodium clusters Na_{n}^{+} in the range n=25-200 at several collision energies. The widely used hard sphere approximation clearly fails for small sizes: not only should vapor-to-liquid nucleation theories be modified, but also, through the microreversibility principle, cluster decay rate statistical models.
@article{arxiv.0711.1797,
title = {Experimental Determination of Nucleation Scaling Law for Small Charged Particles},
author = {Fabien Chirot and Pierre Labastie and Sébastien Zamith and Jean-Marc L'Hermite},
journal= {arXiv preprint arXiv:0711.1797},
year = {2007}
}