Cloud droplets coated with an organic layer have different optical properties and potential to cause rain than uncoated droplets. Atmospheric oxidation of the organic layer in polluted airmasses may decrease drizzle potential and cloud albedo. We have used neutron scattering to demonstrate that the oxidation of an organic surfactant film (oleic acid) on aqueous atmospheric aerosol by atmospheric ozone will hinder cloud droplet growth. Our experiments reveal that the organic film is not destroyed by oxidation but chemically altered to give a film containing about half the original organic material and with a higher surface tension. These results are also important for the study of the stability of organic films on Langmuir troughs towards oxygen and ozone.
MD King (Royal Holloway
University of London), AR Rennie (Uppsala University, Sweden), KC
Thompson (Birkbeck University of London), FN Fisher (Royal Holloway
University of London), CC Dong, RK Thomas (University of Oxford), AV
Research date: December 2007
MD King et al., J. Am. Chem. Soc. 126 (2004) 16710; New Scientist
184 (2004) 2478 p9