Heterogeneous Nucleation Experiments Bridging the Scale from Molecular Ion Clusters to Nanoparticles
Paul M. Winkler,1
Gerhard Steiner,1
Aron Vrtala,1
Hanna Vehkamäki,2
Madis Noppel,3
Kari E. J. Lehtinen,4
Georg P. Reischl,1
Paul E. Wagner,1
Markku Kulmala2*
Generation, investigation, and manipulation of nanostructured materials are of fundamental and practical importance for several disciplines, including materials science and medicine. Recently, atmospheric new particle formation in the nanometer-size range has been found to be a global phenomenon. Still, its detailed mechanisms are mostly unknown, largely depending on the incapability to generate and measure nanoparticles in a controlled way. In our experiments, an organic vapor (n-propanol) condenses on molecular ions, as well as on charged and uncharged inorganic nanoparticles, via initial activation by heterogeneous nucleation. We found a smooth transition in activation behavior as a function of size and activation to occur well before the onset of homogeneous nucleation. Furthermore, nucleation enhancement for charged particles and a substantial negative sign preference were quantitatively detected.
1 Fakultät für Physik, Universität Wien, Boltzmanngasse 5, A-1090 Wien, Austria.
2 University of Helsinki, Department of Physical Sciences, Post Office Box 64, 00014 University of Helsinki, Finland.
3 Institute of Physics, University of Tartu, 18 Ülikooli Street, 50090 Tartu, Estonia.
4 Department of Physics, University of Kuopio and Finnish Meteorological Institute, Post Office Box 1627, 70211 Kuopio, Finland.
* To whom correspondence should be addressed. E-mail: markku.kulmala{at}helsinki.fi
