Atmospheric implication of the hydrogen bonding interaction in hydrated clusters of HONO and dimethylamine in the nighttime.

In this study, the stability of clusters formed by the trans- and cis-isomers of nitrous acid (HONO) with dimethylamine (DMA) and water has been characterized by density functional theory. The large red shifts of the OH-stretching transitions of both HONO isomers in the clusters indicate the formation of strong hydrogen bonds. At standard temperature and pressure, H2O (acceptor) binds to HONO (donor) with binding energies of -25.0 to -24.6 kJ mol-1, less stable than those of DMA (acceptor) with HONO (donor) (-50.5 to -45.3 kJ mol-1). Our findings indicate that hydration enhances proton transfer from HONO to DMA, and consequently increases the interaction strength (binding energies = -67.8 to -78.6 kJ mol-1). The topological and generalized Kohn-Sham energy decomposition confirms strong hydrogen bond interactions. The clustering of HONO with DMA in the atmosphere is negligible as compared to the important H2SO4-DMA clusters.