Molecular constraints on particle growth during new particle formation

Atmospheric new particle formation (NPF) produces large numbers of nanoparticles which can ultimately impact climate. A firm understanding of the identity and contribution of the inorganic and carbonaceous species to nanoparticle growth is required to assess the climatic importance of NPF. Here, we combine elemental and molecular nanoparticle composition measurements to better define the composition and contribution of carbonaceous matter to nanoparticle growth in a rural/coastal environment. We show that carbonaceous matter can account for more than half of the mass growth of nanoparticles and its composition is consistent with that expected for extremely low volatility organic compounds. An important novel finding is that the carbonaceous matter must contain a substantial amount of nitrogen, whose molecular identity is not fully understood. The results advance our quantitative understanding of the composition and contribution of carbonaceous matter to nanoparticle growth, which is essential to more accurately predict the climatic impacts of NPF.