A missing key property in atmospheric aerosol chemistry:  the laplace pressure
Fine aerosol particles are ubiquitous in the atmosphere and have important impacts on climate change and air quality. Organic compounds represent the largest mass fraction of fine particulate matter and their formation is believed to occur through the condensation of oxygenated volatile organic compounds. However, a fundamental physicochemical property of atmospheric aerosols – the Laplace pressure – has never been studied. This “missing” property is expected to have major implications for atmospheric chemistry and may explain the current gaps between ambient observations and modelling studies when evaluating the formation rates, ambient concentrations and the spatial distribution of atmospheric nanoparticles. Hence, my project aims at elucidating the key processes driven by the Laplace pressure in atmospheric aerosols and how they impact on the growth, evolution and physicochemical properties of submicron particles.  MAARvEL focuses on the smallest particles, where the Laplace pressure is expected to have the greatest impact. By exploiting recent instrumental developments and using state-of-the-art mass spectrometry techniques, MAARvEL will provide an unequalled understanding of the processes occurring within the particles. Innovative laboratory experiments will be performed to discover the central role of the Laplace pressure for; (i) condensed-phase reactions, (ii) photochemical processes, and (iii) physicochemical properties of submicron particles. A strong emphasis will be placed on quantifying the extent to which chemical processes govern the growth and evolution of atmospheric nanometre-sized particles.  By revealing how the Laplace pressure controls particle phase chemistry, MAARvEL will provide a major breakthrough to support more accurate predictions of the formation and evolution of atmospheric nanoparticles, thereby decreasing the uncertainties in assessing the magnitude of aerosol effects on climate.