Mass-Mobility-Size for light ions/clusters
Atmospheric new particle formation adds large spatial and temporal variations to the number size distributions of atmospheric aerosol particles, which brings great complexity in evaluating their health and climatic impacts. It is therefore crucial to understand the formation of atmospheric new particles from gas phase and their subsequent growth at a fundamental level. This solution however is obscured by the over-simplified theory in describing the free-molecular mass-mobility-size relationship. The MaSMob-Lion project is proposed to refine the theoretical basis of the mass-mobility-size relationship to improve its accuracy and reliability in describing the initial particle formation from gas phase.  In MaSMob-Lion, the ER will focus on the carrier gas polarizability and conformation effects of <10 nm particles. These effects on mass-mobility relation will be probed experimentally with isomeric monomers and multimers in different carrier gases using the tandem mass-mobility setup and their linkage to particle size will be rationalised through the effective diameter approach with correction terms. Especially, the ER attempts to extend the parameterisations down to the sub-1 nm range for a consistent mass-mobility-size system capable of describing the gas-to-particle phase transition and the subsequent growth. These new knowledges will be used in formulating an easily implementable simple model to assist a quick conversion between mass, mobility and size.  Aerosol particles can be measured by their mass and mobility. But in addition, sub-3 nm particles can also be studied via a growth-based method in a supersaturated condensable vapour. The ER will also conduct alternative and complementary mass-mobility study through supersaturation. While aiming to obtain a holistic picture on the mass-mobility-size relationship that can be used to compare different measurement techniques, these additional data will also be used in model validation and refinement.