Condensation particle counting below 2 nm seed particle diameter and the transition from heterogeneous to homogeneous nucleation

Autor(en)

Paul Winkler, Aron Vrtala, Paul Wagner

Abstrakt

Particle detection by condensation particle counters (CPCs) is ultimately limited by the onset of homogeneous nucleation. At vapour supersaturations around the homogeneous nucleation limit the diameter of critical clusters is typically about 2 nm. It is widely assumed that only particles larger than critical clusters can be activated by vapour condensation and the general detection limit of CPCs is therefore currently accepted to be around 2 nm particle diameter. Using an expansion type CPC with n-propanol as working fluid we investigated the transition from heterogeneous to homogeneous nucleation, clearly showing that particles are activated much before the onset of homogeneous nucleation, even at particle diameters as small as 1.4 nm. For particle diameters below 2 nm we have usually found condensation particle counting to be influenced by the simultaneous presence of ions as generated in a bipolar diffusion charger. In this paper we illustrate how the presence of ions influences particle number concentration measurement and how ions can be removed in order to obtain accurate seed particle number concentrations for particle diameters down to 1 nm.

Organisation(en)

Aerosolphysik und Umweltphysik

Journal

Atmospheric Research

Band

90

Seiten

125-131

Anzahl der Seiten

7

ISSN

0169-8095

DOI

https://doi.org/10.1016/j.atmosres.2008.01.001

Publikationsdatum

2008

Peer-reviewed

Ja

ÖFOS 2012

103008 Experimentalphysik, 210006 Nanotechnologie

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/679bfd1c-3447-4359-9b78-afb0bc45753b