The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here:

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Portrait of Joakim Pagels

Joakim Pagels

Senior Lecturer

Portrait of Joakim Pagels

Immersion freezing ability of freshly emitted soot with various physico-chemical characteristics


  • John Falk
  • Kimmo Korhonen
  • Vilhelm B. Malmborg
  • Louise Gren
  • Axel C. Eriksson
  • Panu Karjalainen
  • Lassi Markkula
  • Per Erik Bengtsson
  • Annele Virtanen
  • Birgitta Svenningsson
  • Joakim Pagels
  • Thomas B. Kristensen

Summary, in English

The immersion freezing ability of soot particles has in previous studies been reported in the range of low/insignificant to very high. The aims of this study were to: (i) perform detailed physico-chemical characterisation of freshly produced soot particles with very different properties, (ii) investigate the immersion freezing ability of the same particles, and (iii) investigate the potential links between physico-chemical particle properties and ice-activity. A miniCAST soot generator was used to produce eight different soot samples representing a wide range of physico-chemical properties. A continuous flow diffusion chamber was used to study each sample online in immersion mode over the temperature (T) range from −41 to −32C, at a supersaturation of about 10% with respect to liquid water. All samples exhibited low to no heterogeneous immersion freezing. The most active sample reached ice-activated fractions (AF) of 10−3 and 10−4 at temperatures of 1.7 and 1.9 K, respectively, above the homogeneous freezing temperature. The samples were characterized online with respect to a wide range of physico-chemical properties including effective particle density, optical properties, particle surface oxidation and soot maturity. We did observe indications of increasing immersion freezing ice-activity with increasing effective particle density and increasing particulate PAH fraction . Hence, those properties, or other properties co-varying with those, could potentially enhance the immersion freezing ice-activity of the studied soot particle types. However, we found no significant correlation between the physico-chemical properties and the observed ice-nucleating ability when the particle ensemble was extended to include previously published results including more ice-active biomass combustion soot particles. We conclude that it does not appear possible in general and in any straightforward way to link observed soot particle physico-chemical properties to the ice-nucleating ability using the online instrumentation included in this study. Furthermore, our observations support that freshly produced soot particles with a wide range of physico-chemical properties have low to insignificant immersion freezing ice-nucleating ability.


  • Nuclear physics
  • Centre for Environmental and Climate Science (CEC)
  • Ergonomics and Aerosol Technology
  • Combustion Physics
  • Metalund
  • NanoLund: Center for Nanoscience

Publishing year










Document type

Journal article




  • Meteorology and Atmospheric Sciences
  • Atom and Molecular Physics and Optics
  • Other Physics Topics


  • Aerosol
  • Black carbon
  • Brown carbon
  • Ice nucleation
  • Immersion freezing
  • MiniCAST
  • Soot
  • SPIN




  • ISSN: 2073-4433