Homogeneous and heterogeneous clustering in the accretion regime
Laboratoire Aimé Cotton, C.N.R.S. UPR 3321, bâtiment 505, Université Paris-Sud, 91405 Orsay Cedex, France
Corresponding author: a email@example.com
Revised: 23 September 2006
Published online: 24 May 2007
Condensation of nano-droplets in a supersaturating vapor decomposes in two steps: the formation of a nucleation center, also called critical nuclei or nucleation seed, and the growth sequence, by accretion of further atoms on the nucleation center. These two steps have been investigated separately through the clustering of homogeneous particles Nan and heterogeneous particles NanX in a helium buffer gas (X = (Na2O)2 or (NaOH)2). The growth sequence is analyzed with preformed molecules X injected in a supersaturating sodium vapor and driving production of NanX clusters. Cluster distribution mean sizes are controlled by sodium concentration and by the condensation cell effective length. The signal intensities observed for homogeneous and heterogeneous clusters are proportional to the homogeneous and heterogeneous nucleation center numbers respectively. We can measure the efficiency for the homogeneous nucleation center production versus sodium concentration. This process is the onset of the condensation phase transition.
PACS: 36.40.-c – Atomic and molecular clusters / 36.40.Jn – Reactivity of clusters / 36.40.Sx – Diffusion and dynamics of clusters
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2007