Abstract. Sea-salt aerosol (SSA) particles are ubiquitous in the marine boundary layer and over coastal areas. Therefore SSA have ability to directly indirectly affect Earth's radiation balance. The influence on climate is related their water uptake ice nucleation characteristics. In this study, optical microscopy coupled with Raman spectroscopy was used detect formation of a crystalline NaCl hydrate that could form under atmospheric conditions. NaCl(s) (~1 10 μm diameter) deliquesced at...

ConspectusThe interactions of aerosol particles with light and clouds are among the most uncertain aspects anthropogenic climate forcings. The effects on depend their optical properties, heterogeneous chemistry, water uptake behavior, ice nucleation activity. These properties in turn physics chemistry including composition, size, shape, internal structure (morphology), phase state. greatest numbers found at small, submicrometer sizes, can differ nanoscale compared measurements bulk...

The effects of aerosol particles on heterogeneous atmospheric chemistry and climate are determined in part by the internal arrangement compounds within particles. We have used cryo-transmission electron microscopy to investigate phase separation behavior model organic composed ammonium sulfate internally mixed with succinic or pimelic acid. found that no particle a diameter <170 nm for acid 270 is separated. Larger adopt separated, partially engulfed structure. therefore demonstrate...

pH is one of the most basic chemical properties aqueous solution, but its measurement in nanoscale aerosol particles presents many challenges. The growing interest atmospheric chemistry community because demonstrated effects on heterogeneous and human health, as well potential climate. authors have shown that phase transitions are sensitive to pH, focusing systems undergo liquid-liquid separation. Currently, calculated indirectly from knowledge species present gas phases through use...

Abstract. Amorphous (semi-)solid organic aerosol particles have the potential to serve as surfaces for heterogeneous ice nucleation in cirrus clouds. Raman spectroscopy and optical microscopy been used conjunction with a cold stage examine water uptake on individual amorphous at atmospherically relevant temperatures (200–273 K). Three compounds considered proxies atmospheric secondary (SOA) were this investigation: sucrose, citric acid glucose. Internally mixed consisting of each ammonium...

We have investigated the optical properties of internally mixed aerosol particles composed dicarboxylic acids and ammonium sulfate using cavity ring-down extinction spectroscopy at a wavelength 532 nm. The real refractive indices these nonabsorbing species were retrieved from concentration Mie scattering theory. obtain for pure that are consistent with literature values, where they exist, to within experimental error. For particles, however, our data deviates significantly volume-weighted...

Secondary organic aerosol makes up a significant fraction of the total mass, and growing body evidence indicates that reactions in atmospheric aqueous phase are important contributors to formation can help explain observations cannot be accounted for using traditional gas-phase chemistry. In particular, between small molecules have been proposed as source light absorbing compounds observed numerous locations. Past work has established α-dicarbonyls amines evaporating water droplets produces...

Atmospheric aerosol particles influence climate through their direct and indirect effects. These impacts depend in part on the morphology of particles, which is determined by composition. The effect pH was investigated using composed 3-methylglutaric acid ammonium sulfate manipulating starting bulk solution addition aqueous sodium hydroxide. Efflorescence, deliquescence, phase separation, mixing transitions were observed with optical microscopy. Due to changes its protonation states,...

The morphology of aerosol particles impacts their role in the climate system. In submicron size regime, that undergo liquid-liquid phase separation is dependent on size, where for some systems small are homogeneous and large phase-separated. We use cryogenic transmission electron microscopy to probe model organic systems. observe transition region (where both phase-separated morphologies seen) spans 121 nm at fastest drying rates with a midpoint diameter > 170 nm. By slowing rate over...

Physical properties of aerosol particles, such as liquid-liquid phase separation (LLPS), have the potential to impact climate system. Model systems been shown size-dependent LLPS in submicron regime; however, these are an extreme simplification ambient aerosol, which can include myriad organic compounds. We expand studies particles consisting ammonium sulfate and more complex mixtures from multiple compounds α-pinene secondary matter (SOM). All display a morphology, with small remaining...

The effects of aerosol particles on heterogeneous atmospheric chemistry and climate are determined in part by the internal arrangement compounds within particles. To characterize morphology internally mixed accumulation mode size regime, we have used cryo-transmission electron microscopy to investigate phase separation behavior dry, submicrometer composed ammonium sulfate with carboxylic acids (adipic, azelaic, citric, glutaric, malonic, pimelic, suberic, succinic acid). Determining dry is...

Few aerosol particles in clouds nucleate the formation of ice. The surface sites available for nucleus formation, which can include defects and functional groups, determine part activity an particle toward ice formation. Although nucleation on has been widely studied, exploration specific at initial germ forms limited, but is important predicting microphysical properties clouds, impact climate. This Perspective focuses what currently known about aluminosilicate clay minerals, are commonly...

Cloud condensation nuclei (CCN) activation is sensitive to the size, composition, and morphology of aerosol particles <200 nm. By controlling particle internally mixed samples (i.e., homogeneous versus phase separated), we have probed effect on CCN activity using model organic systems, where ammonium sulfate was with either pimelic acid or succinic in a 50:50 mixture by weight. Surprisingly, for systems same composition but distinct morphology, observe noticeable impact activity....

The origins of the size dependent morphology organic aerosol are explored by probing poly(ethylene glycol)-400/ammonium sulfate mixtures using cryogenic-transmission electron microscopy. Surprisingly, we observe a dependence at some compositions, but not others. Our results suggest that occurs due to an activated process.

Water-soluble organic compounds (WSOCs) readily uptake water and form atmospheric droplets. Understanding the water-uptake ability of these WSOCs can improve our understanding their radiative effects thus current climate models. In this study, we measure subsaturated supersaturated droplet growth four WSOCs: levoglucosan, sucrose, raffinose, trehalose. Specifically, use three distinct nanoscale methods: cavity ring-down spectroscopy (CRDS), hygroscopic tandem differential mobility analysis...

Mineral dust is the second largest atmospheric emission by mass and one of least understood sources. The shape particles depends on their composition has implications for particle optical properties reactive surface area. are often approximated as spheroids to model properties. In this study, scanning electron microscopy (SEM) used measure aspect ratios calcite, quartz, NX-illite, kaolinite (KGa-1b KGa-2), montmorillonite (STx-1b SWy-2). addition traditional SEM images top particles,...

Aerosol particle morphology influences the effect of particles on climate. Recent studies have documented high acidity found in many ambient aerosol particles. The this phase transitions mixed organic/inorganic has not been addressed. To investigate effect, six organic compounds and ammonium sulfate were investigated individually with varying amounts sulfuric acid to determine role low pH separation, efflorescence, deliquescence transitions. All affected by addition acid. This was attributed...

We have explored the direct and indirect radiative effects on climate of organic particles likely to been present early Earth by measuring their hygroscopicity cloud nucleating ability. The analog aerosol were generated via ultraviolet photolysis an gas mixture, which was designed mimic possible atmospheric conditions before rise oxygen. An for present-day atmosphere Saturn's moon Titan tested comparison. exposed a range relative humidities (RHs). Water uptake onto observed occur over entire...

Mineral dust aerosol is one of the largest contributors to global ice nuclei, but physical and chemical processing during atmospheric transport can alter its nucleation activity. In particular, several recent studies have noted that sulfuric nitric acids inhibit heterogeneous in regime below liquid water saturation aluminosilicate clay minerals. We exposed kaolinite, KGa-1b KGa-2, montmorillonite, STx-1b SWy-2, aqueous acid determine changes are responsible for observed deactivation. To...

Aerosol morphology influences the interactions of particles with light, water uptake, and heterogeneous chemistry. Through these mechanisms, may be important to role aerosol on climate system. A factor that impacts is diverse complex mixture organic compounds make up in atmosphere. In this paper, we investigate effect sucrose liquid–liquid phase separation. As amount increased, oxygen carbon ratio (O:C) increases. We show particle changes as O:C increased separation causing take a textured...

Aerosols are present as complex organic-inorganic mixtures within our atmosphere, resulting in particles presenting phase separated morphology. Mixed aerosols can be predominantly found nascent sea spray (SSA). When these exposed to supersaturated conditions (&gt;100% RH), the water uptake ability of vary based on composition mixture. Previous studies have characterized systems through determination an average oxygen carbon (O/C) ratio where liquid-liquid separation (LLPS) reaches its limit....

The aerosol direct effect, which characterizes the interaction of radiation with particles, remains poorly understood. By determining composition, shape, and internal structure, we can predict optical properties. In this study, performed a feasibility study to determine if tapping-mode atomic force microscopy (TM-AFM) Raman be effectively used obtain information on structure. These techniques are advantageous because they operate under ambient pressure temperature. We worked model particles...