Aerosol optical tweezers are used to probe the oxidative ageing by ozone of single, mixed component particles consisting of sodium chloride and either oleic or maleic acid. Changes in the particle composition and properties including size and refractive index are probed using cavity enhanced Raman spectroscopy (CERS). All the particles decreased in size following oxidation due to the formation and subsequent evaporation of volatile products, with those containing oleic acid also being found to become inhomogeneous in composition1. In addition, changes in the particle refractive index and hygroscopicity were also inferred.
