Year: 2026
Type: preprint
Abstract: New particle formation is widely observed in organic-rich atmospheric environments where sulfuric acid and basic vapors appear scarce, yet what initiates nucleation and what role trace inorganic acid–base species play remain unclear. Guided by laboratory experiments and field observations, we resolve this ambiguity with a bottom-up framework bridging molecular energetics and nucleation kinetics, tracking nucleation from molecular origin to measurable formation rates. We uncover a hidden pathway in which a multifunctional oxygenated organic molecule (OOM) hydrogen-bonds simultaneously to sulfuric acid and ammonia, inducing proton transfer and stabilizing a charge-separated HSO 4 - –NH 4 + ion pair. This ion pair forms a localized electrostatic scaffold that recruits additional OOMs into a charge-assisted hydrogen-bond network, yielding stable embryonic clusters. Remarkably, a single ion pair unlocks this mechanism, indicating that even trace inorganic species can be indispensable nucleation triggers. Operating across diverse biogenic and anthropogenic OOM systems, ion-pair-scaffolded nucleation may be ubiquitous in the atmosphere.
Source: ChemRxiv
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
Funder: Max-Planck-Gesellschaft
OpenAlex ID: W7213330150