Deliquescence and Efflorescence Processes of Aerosol Particles Studied by<i>in situ</i>FTIR and Raman Spectroscopy

Zhao, Lijun; Wang, Rui; Zhang, Kun; Zeng, Qingxuan; Zhang, Yunhong

doi:10.1088/1674-0068/21/01/1-11

Cited by 18 publications

(8 citation statements)

References 100 publications

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“…Deliquescence is the dissolution of the salt particle in the water vapor of the surrounding air, which occurs when the vapor pressure of the surrounding air equals or exceeds DRH. The salts absorb exponentially more water with further increasing humidity (Pilinis et al, 1989; Zhao et al, 2008; Mauer and Taylor, 2010). This mechanism is similar to the activation of cloud condensation nuclei, although DRH is slightly different for deposited particles (Gao et al, 2007).…”

Section: Processes Leading To Microscopic Leaf Wetnessmentioning

confidence: 99%

“Breath figures” on leaf surfaces—formation and effects of microscopic leaf wetness

2013

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“Microscopic leaf wetness” means minute amounts of persistent liquid water on leaf surfaces which are invisible to the naked eye. The water is mainly maintained by transpired water vapor condensing onto the leaf surface and to attached leaf surface particles. With an estimated average thickness of less than 1 μm, microscopic leaf wetness is about two orders of magnitude thinner than morning dewfall. The most important physical processes which reduce the saturation vapor pressure and promote condensation are cuticular absorption and the deliquescence of hygroscopic leaf surface particles. Deliquescent salts form highly concentrated solutions. Depending on the type and concentration of the dissolved ions, the physicochemical properties of microscopic leaf wetness can be considerably different from those of pure water. Microscopic leaf wetness can form continuous thin layers on hydrophobic leaf surfaces and in specific cases can act similar to surfactants, enabling a strong potential influence on the foliar exchange of ions. Microscopic leaf wetness can also enhance the dissolution, the emission, and the reaction of specific atmospheric trace gases e.g., ammonia, SO2, or ozone, leading to a strong potential role for microscopic leaf wetness in plant/atmosphere interaction. Due to its difficult detection, there is little knowledge about the occurrence and the properties of microscopic leaf wetness. However, based on the existing evidence and on physicochemical reasoning it can be hypothesized that microscopic leaf wetness occurs on almost any plant worldwide and often permanently, and that it significantly influences the exchange processes of the leaf surface with its neighboring compartments, i.e., the plant interior and the atmosphere. The omission of microscopic water in general leaf wetness concepts has caused far-reaching, misleading conclusions in the past.

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Section: Processes Leading To Microscopic Leaf Wetnessmentioning

confidence: 99%

“Breath figures” on leaf surfaces—formation and effects of microscopic leaf wetness

2013

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“…In this manner, solid aerosols were observed to become droplets as they took up water from the gas phase (deliquescence) or liquid particles became solid as they lost water (efflorescence). Other measurement techniques that have been used to investigate aerosol-phase changes include single particle levitation coupled with spectroscopy (Raman, Mie resonance, micro-FTIR) as well as different types of microscopy on a substrate (Liu et al, 2008;Zhao et al, 2008;Parsons et al, 2006;Bertram et al, 2011). Many microscopy techniques require depositing particles on a hydrophobic slide, which represents a possible surface for heterogeneous phase transition (Liu et al, 2008;Bertram et al, 2011).…”

Section: A Zawadowicz Et Al: Hygroscopic and Phase Separation Prmentioning

confidence: 99%

“…Many microscopy techniques require depositing particles on a hydrophobic slide, which represents a possible surface for heterogeneous phase transition (Liu et al, 2008;Bertram et al, 2011). Levitation techniques, such as electrodynamic balance, acoustic suspension and light pressure suspension coupled with spectroscopy are well suited for studying condensation and freezing events on single particles but not the properties of a multi-particle flow (Zhao et al, 2008;Parsons et al, 2006). The technique used in this study, FTIR coupled with a flow tube setup, can also access sizes smaller than 1 µm diameter and therefore can be used to study liquid-liquid phase separation and DRH/ERH properties in small particles relevant to the atmosphere.…”

Section: A Zawadowicz Et Al: Hygroscopic and Phase Separation Prmentioning

confidence: 99%

Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions

et al. 2015

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Abstract. Atmospheric aerosol particles are often partially or completely composed of inorganic salts, such as ammonium sulfate and sodium chloride, and therefore exhibit hygroscopic properties. Many inorganic salts have well-defined deliquescence and efflorescence points at which they take up and lose water, respectively. Field measurements have shown that atmospheric aerosols are not typically pure inorganic salt, instead, they often also contain organic species. There is ample evidence from laboratory studies that suggests that mixed particles exist in a phase-separated state, with an aqueous inorganic core and organic shell. Although phase separation has not been measured in situ, there is no reason it would not also take place in the atmosphere. Here, we investigate the deliquescence and efflorescence points, phase separation and ability to exchange gas-phase components of mixed organic and inorganic aerosol using a flow tube coupled with FTIR (Fourier transform infrared) spectroscopy. Ammonium sulfate aerosol mixed with organic polyols with different O : C ratios, including 1,4-butanediol, glycerol, 1,2,6-hexanetriol, 1,2-hexanediol, and 1,5-pentanediol have been investigated. Those constituents correspond to materials found in the atmosphere in great abundance and, therefore, particles prepared in this study should mimic atmospheric mixed-phase aerosol particles. Some results of this study tend to be in agreement with previous microscopy experiments, but others, such as phase separation properties of 1,2,6-hexanetriol, do not agree with previous work. Because the particles studied in this experiment are of a smaller size than those used in microscopy studies, the discrepancies found could be a size-related effect.

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“…75% for NaCl or NaClO 3 , 40% for NH 4 HSO 4 and 80% for (NH 4 ) 2 SO 4 ). The salts absorb exponentially more water with further increasing humidity (Pilinis et al ., ; Zhao et al ., ; Mauer & Taylor, ). This mechanism is similar to the activation of cloud condensation nuclei, although DRH is slightly different for deposited particles (Gao et al ., ), and plant transpiration provides an additional water vapour source (Burkhardt & Eiden, ).…”

Section: Introductionmentioning

confidence: 99%

Stomatal penetration by aqueous solutions – an update involving leaf surface particles

et al. 2012

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SummaryThe recent visualization of stomatal nanoparticle uptake ended a 40-yr-old paradigm. Assuming clean, hydrophobic leaf surfaces, the paradigm considered stomatal liquid water transport to be impossible as a result of water surface tension. However, real leaves are not clean, and deposited aerosols may change hydrophobicity and water surface tension.Droplets containing NaCl, NaClO 3 , (NH 4 ) 2 SO 4 , glyphosate, an organosilicone surfactant or various combinations thereof were evaporated on stomatous abaxial and astomatous adaxial surfaces of apple (Malus domestica) leaves. The effects on photosynthesis, necrosis and biomass were determined. Observed using an environmental scanning electron microscope, NaCl and NaClO 3 crystals on hydrophobic tomato (Solanum lycopersicum) cuticles underwent several humidity cycles, causing repeated deliquescence and efflorescence of the salts.All physiological parameters were more strongly affected by abaxial than adaxial treatments. Spatial expansion and dendritic crystallization of the salts occurred and cuticular hydrophobicity was decreased more rapidly by NaClO 3 than NaCl.The results confirmed the stomatal uptake of aqueous solutions. Humidity fluctuations promote the spatial expansion of salts into the stomata. The ion-specific effects point to the Hofmeister series: chaotropic ions reduce surface tension, probably contributing to the defoliant action of NaClO 3 , whereas the salt spray tolerance of coastal plants is probably linked to the kosmotropic nature of chloride ions.

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Deliquescence and Efflorescence Processes of Aerosol Particles Studied byin situFTIR and Raman Spectroscopy

Cited by 18 publications

References 100 publications

“Breath figures” on leaf surfaces—formation and effects of microscopic leaf wetness

“Breath figures” on leaf surfaces—formation and effects of microscopic leaf wetness

Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions

Stomatal penetration by aqueous solutions – an update involving leaf surface particles

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