Enhancing effects of glycine on methanesulfonic acid-driven new particle formation: Mechanistic insights and implications for atmospheric pollution.

New particle formation (NPF) influences the concentration of marine aerosols, and amino acids are important components of marine particulate matter. Glycine (Gly), the simplest and one of the most abundant amino acids in the atmosphere, has an unclear mechanism regarding its involvement in driving the nucleation of methanesulfonic acid (MSA). This study employs the density functional theory at DLPNO-CCSD(T)/aug-cc-pVTZ//ωB97X-D/6-31++G(d,p) level and the Atmospheric Cluster Dynamics Code (ACDC) to investigate the nucleation processes of the (Gly)(MSA) (m = 0-4 and n = 0-4) system. The results reveal that glycine can establish a one-to-one proton transfer pattern with MSA. The carboxyl (-COOH) and amino (-NH) groups of Gly can form hydrogen bonds with MSA in two orientations, thereby enhancing clusters stability. In the context of MSA-driven NPF, Gly exhibits a similar enhancing potential to methylamine. Additionally, we further investigate the effects of ion-induced nucleation, demonstrating that positive ions (e.g., HO and NH) enhance nucleation more effectively than negative ions (e.g., NO, HSO and MSA), as they can form additional hydrogen bonds with dimer clusters. In particular, HO exerts a stronger stabilizing effect on Gly-rich clusters. These findings highlight the potential role of Gly in coastal and marine NPF events.