SSA particles have been historically regarded as being mainly composed of sea salt, i.e. 4–6 Climate-relevant physicochemical properties of aerosols, including CCN/IN activity and optical properties, depend on particle size and chemical composition, which, in turn, are controlled by chemical and physical interactions that occur at the interface between the particle and gas phase, a region that is notoriously difficult to access experimentally.

1–3 SSA particles influence the earth's climate by absorption and scattering of solar radiation and through their propensity to act as cloud condensation nuclei (CCN) and ice nuclei (IN). Introduction Oceans cover 71% of the earth's surface, and the flux of sea spray aerosol (SSA) is the largest source of aerosol particles in the atmosphere. It also provides insights into the development of model systems for SSA that may more accurately represent the organic layer at the surface. This study provides new insights into the bulk and surface composition of SSA particles and represents a step forward in our understanding of this globally abundant aerosol. Changes in peak frequencies and relative intensities in the C–H stretching region are seen for some particles after the addition of bacteria, phytoplankton, and growth medium to the seawater. The presence of methylene contributions in the SFG spectra indicated disordered alkyl chains, in contrast to what one might expect for a surfactant layer on a sea salt particle. This finding suggests that organic material present in supermicrometer particles primarily resides at the interface. particles without a solid inclusion), and also the interfaces of mixed-phase particles, there was a strong SFG response in the aliphatic C–H stretching region for both sub- and supermicrometer particles. However, for external surfaces of homogeneous SSA particles ( i.e. In particular, submicrometer particles exhibited a larger amount of organic matter compared to supermicrometer particles. The relative intensities of these features showed a strong dependence on particle size.

Raman spectra of single particles have bands in the 980 to 1030 cm −1 region associated with the symmetric stretch of the sulfate anion, the 2800 to 3000 cm −1 region associated with carbon–hydrogen stretches, and from 3200–3700 cm −1 associated with the oxygen–hydrogen stretches of water. 0.15 to 10 μm is measured using Raman microspectroscopy, while the interfacial composition of collections of size-resolved particles is probed by sum frequency generation ( SFG). The composition of individual SSA particles ranging in size from ca. In this study, nascent SSA particles were produced using breaking waves, resulting in compositions and sizes representative of the open ocean. SSA is comprised of a mixture of inorganic and organic components in varying proportions that change as a function of particle size and seawater composition. SSA plays a major role in influencing climate however the overall impacts remain poorly understood due to the overall chemical complexity.

Sea spray aerosol (SSA) represents one of the largest aerosol components in our atmosphere.

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