Molecular Chirality and Cloud Activation Potentials of Dimeric α-Pinene Oxidation Products

Abstract

The surface activity of ten atmospherically relevant α-pinene-derived dimers having varying terminal functional groups and backbone stereochemistry is reported. We find ∼10% differences in surface activity between diastereomers of the same dimer, demonstrating that surface activity depends upon backbone stereochemistry. Octanol–water (K OW ) and octanol–ammonium sulfate partitioning coefficient (K OAS ) measurements of our standards align well with the surface activity measurements, with the more surface-active dimers exhibiting increased hydrophobicity. Our findings establish a link between molecular chirality and cloud activation potential of secondary organic aerosol particles. Given the diurnal variations in enantiomeric excess of biogenic emissions, possible contributions of such a link to biosphere:atmosphere feedbacks as well as aerosol particle viscosity and phase separation are discussed.

Absolute optical chiral analysis using cavity-enhanced polarimetry

“…Furthermore, the absolute optical chiral analysis approach and technique that we present in this work can enable in situ real-time observations of the role of chirality in the oxidation products of chiral BVOCs, which, in turn, contribute to the production of secondary organic aerosol particles ( 51 , 52 ). Therefore, our approach can allow for novel insights into not only the formation but also transformation processes of atmospheric aerosols and assist in determining their climate-relevant properties, as in the case of, e.g., establishing a link between molecular chirality and cloud activation potential of secondary organic aerosol particles ( 53 , 54 ).…”

Chiral monoterpenes reveal forest emission mechanisms and drought responses

“…This underlines that a new, enantiomerically specific approach to emission modelling, based on the enzyme-group model proposed here, would be more accurate and biologically founded than current approaches 36 , in particular with regards to a possible feedback between emission composition and particle production efficiency. Whereas monoterpene enantiomers exhibit no difference in physical properties, in oxidation rates by OH or O 3 , or in uptake rates to typical Amazon forest aerosol samples 8 , recent work has shown that dimeric photochemical product combinations do indeed have different hydrophobicities 37 . It should be noted that these conclusions are based on the assumption that the B2-TRF does represent the characteristic drought response of real-world tropical rainforests in the absence of atmospheric chemistry.…”

Emerging investigator series: surfactants, films, and coatings on atmospheric aerosol particles: a review

“…12,14,[402][403][404][405][406][407] In the case of dimeric a-pinene oxidation products, the surface propensity has been shown to depend on stereochemistry. 408 Ishizuka et al 409 present an interesting case study of how surfactants already present at the air-water interface affect the interfacial oligomerization of isoprene. They monitored the reaction of gas-phase isoprene with liquid microjets of aqueous solutions containing either the nonionic surfactant 1-octanol or a cationic quaternary ammonium surfactant.…”