Water Accommodation on Ice and Organic Surfaces: Insights from Environmental Molecular Beam Experiments

Abstract

Water uptake on aerosol and cloud particles in the atmosphere modifies their chemistry and microphysics with important implications for climate on Earth. Here, we apply an environmental molecular beam (EMB) method to characterize water accommodation on ice and organic surfaces. The adsorption of surface-active compounds including short-chain alcohols, nitric acid, and acetic acid significantly affects accommodation of D2O on ice. n-Hexanol and n-butanol adlayers reduce water uptake by facilitating rapid desorption and function as inefficient barriers for accommodation as well as desorption of water, while the effect of adsorbed methanol is small. Water accommodation is close to unity on nitric-acid- and acetic-acid-covered ice, and accommodation is significantly more efficient than that on the bare ice surface. Water uptake is inefficient on solid alcohols and acetic acid but strongly enhanced on liquid phases including a quasi-liquid layer on solid n-butanol. The EMB method provides unique information on accommodation and rapid kinetics on volatile surfaces, and these studies suggest that adsorbed organic and acidic compounds need to be taken into account when describing water at environmental interfaces.

Understanding water interactions with organic surfaces: environmental molecular beam and molecular dynamics studies of the water–butanol system

“…Water molecules that scatter from the surface are observed to leave with 10-40% of their incident kinetic energy, a result that agrees well with MD simulations and with earlier EMB studies of water interactions with organic surfaces. [16][17][18]36 Angular distributions of the scattered intensity and kinetic energy provide additional information about the water-surface interactions. The angular distributions for IS are broad for both liquid and solid n-butanol, while the results are consistent with a smoother surface near the melting point.…”

“…15 Likewise, environmental molecular beam (EMB) studies have provided an improved understanding of water interactions with more volatile organic phases. [16][17][18] Exploratory studies of alcohols, acetic acid and nopinone show limited water uptake on solid phases, but a strong enhancement on liquid phases. Intriguingly, water accommodation on n-butanol changes rapidly with temperature near the melting point, which indicates that the surface layer has unique properties that deviate substantially from the bulk.…”

A quasi‐liquid mediated continuum model of faceted ice dynamics

“…These observations suggest that control of bulk accommodation lies not at the interface between the QLL and vapor but at the ice‐like/quasi‐liquid interface. Indeed, a two‐stage kinetic scheme embodying these ideas has been demonstrated to successfully account for accommodation measurements across a wide range of temperatures [ Kong , ; Kong et al , ]. Bolstering this view is evidence that the development and propagation of steps is facet‐specific; i.e., they are processes that are sensitive to the symmetry of the underlying facet [ Libbrecht , , , ; Libbrecht and Rickerby , ]; this implies microscopic influence over those processes.…”

Deposition-mode ice nucleation reexamined at temperatures below 200 K

“…Chem. Phys., 15, 1621-1632, 2015 www.atmos-chem-phys.net/15/1621/2015/ Kong et al (2014) and present study used in this study, which are expected to have a well-ordered close packed structure. Similar MD simulations do not exist for HxOH and with the present experimental system it is impossible to distinguish the expected H 2 O binding energy with a HxOH monolayer from that of BuOH.…”