Three-body collisions as a particle formation mechanism in silver nanoparticle synthesis.
Silver nanoparticles were prepared in a tubular flow reactor using an evaporation-condensation technique. The size distribution of the particles was measured using standard aerosol instruments and electron microscopy. A comparison with results obtained by a discrete population balance model with molecule-by-molecule resolution suggest that the particles probably nucleate kinetically through a dimerization process instead of a thermodynamic pathway over a free energy barrier, as is typically described by classical nucleation theory. Furthermore, the kinetic rate of dimerization seems to be accompanied by a correction term, associated with the requirement of energy and momentum conservation in molecule-molecule collisions. This energy conservation requires the presence of three-body collisions at the very initial step of particle formation.
Lehtinen
Kari E J
KE
University of Helsinki, Department of Physical Sciences, PO Box 64, 00014 Helsinki, Finland. kari.lehtinen@helsinki.fi
Backman
Ulrika
U
Jokiniemi
Jorma K
JK
Kulmala
Markku
M