Exploring the complexity of aerosol particle properties and processes using single particle techniques

Krieger, Ulrich K.; Marcolli, Claudia; Reid, Jonathan P.

doi:10.1039/c2cs35082c

Cited by 338 publications

(465 citation statements)

References 241 publications

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“…As a robust methodology for the levitation of single particles which carry electric charge, the electrodynamic balance (EDB) technique has been applied in atmosphere science for several decades (see reviews by Davis, 1997;Krieger et al, 2012). On the base of such a strategy, numerous studies have been carried out on aerosol particles and droplets, including but not limited to contact ion pairs formation (e.g.…”

Section: H-j Tong Et Al: a New Electrodynamic Balance (Edb) Designmentioning

confidence: 99%

A new electrodynamic balance (EDB) design for low-temperature studies: application to immersion freezing of pollen extract bioaerosols

et al. 2015

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Abstract. In this paper we describe a newly designed cold electrodynamic balance (CEDB) system, built to study the evaporation kinetics and freezing properties of supercooled water droplets. The temperature of the CEDB chamber at the location of the levitated water droplet can be controlled in the range −40 to +40 • C, which is achieved using a combination of liquid nitrogen cooling and heating by positive temperature coefficient heaters. The measurement of liquid droplet radius is obtained by analysing the Mie elastic light scattering from a 532 nm laser. The Mie scattering signal was also used to characterise and distinguish droplet freezing events; liquid droplets produce a regular fringe pattern, whilst the pattern from frozen particles is irregular. The evaporation rate of singly levitated water droplets was calculated from time-resolved measurements of the radii of evaporating droplets and a clear trend of the evaporation rate on temperature was measured. The statistical freezing probabilities of aqueous pollen extracts (pollen washing water) are obtained in the temperature range −4.5 to −40 • C. It was found that that pollen washing water from water birch (Betula fontinalis occidentalis) pollen can act as ice nuclei in the immersion freezing mode at temperatures as warm as −22.45 (±0.65) • C. Furthermore it was found that the protein-rich component of the washing water was significantly more iceactive than the non-proteinaceous component.

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Section: H-j Tong Et Al: a New Electrodynamic Balance (Edb) Designmentioning

confidence: 99%

A new electrodynamic balance (EDB) design for low-temperature studies: application to immersion freezing of pollen extract bioaerosols

et al. 2015

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“…Studies on single particles, confined within optical or electrodynamic traps, now provide precise measurements of aerosol refractive indices and phases, hygroscopic growth, evaporation of semi-volatile components, and other properties of importance for their atmospheric behaviour. [2][3][4][5][6] These trapping-based techniques are most applicable to single particles with radii greater than 1 μm, but the smaller accumulation mode particles are of greater significance for atmospheric processes. 4 In a recent publication, we demonstrated that absolute extinction cross sections for single submicron radius spherical aerosol particles can be measured with high precision by combining optical confinement and levitation of a particle with cavity ring-down spectroscopy (CRDS).…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4][5][6] These trapping-based techniques are most applicable to single particles with radii greater than 1 μm, but the smaller accumulation mode particles are of greater significance for atmospheric processes. 4 In a recent publication, we demonstrated that absolute extinction cross sections for single submicron radius spherical aerosol particles can be measured with high precision by combining optical confinement and levitation of a particle with cavity ring-down spectroscopy (CRDS). 7 The change in ring-down time (RDT) when a particle is moved from well below the optical axis (z) of the ring-down cavity (RDT = 0) to the height of the centre axis of the Gaussian TEM00 cavity mode (RDT = ) is given by:…”

Section: Introductionmentioning

confidence: 99%

Deviations from Plane-Wave Mie Scattering and Precise Retrieval of Refractive Index for a Single Spherical Particle in an Optical Cavity

et al. 2014

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. (0)117 9287672 e-mail: a.orr-ewing@bristol.ac.uk AbstractThe extinction cross sections of individual, optically confined aerosol particles with radii of a micron or less can, in principle, be measured using cavity ring-down spectroscopy (CRDS). However, when the particle radius is comparable in magnitude to the wavelength of light stored in a high-finesse cavity, the phenomenological cross-section retrieved from a CRDS experiment depends on the location of the particle in the intra-cavity standing wave and differs from the Mie scattering cross section for plane-wave irradiation. Using an evaporating 1,2,6-hexanetriol particle of initial radius ~1.75 m confined within the 4.5-m diameter core of a Bessel beam, we demonstrate that the scatter in the retrieved extinction efficiency of a single particle is determined by its lateral motion, which spans a few wavelengths of the intra-cavity standing wave used for CRDS measurements. Fits of experimental measurements to Mie calculations, modified to account for the intra-cavity standing wave, allow precise retrieval of the refractive index of 1,2,6-hexanetriol particles (with relative humidity, RH < 10%) of 1.47824  0.00072.

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“…23−25 To address the challenges in quantifying hygroscopicity for aerosols of complex composition, refinements in laboratory and field instrumentation, and improved frameworks for representing hygroscopicity, are required. 26,27 Hygroscopic growth measurements must be made up to water activities close to the dilute limit, ideally as high as 0.999. Such high water activities (a w ) are required for measurements to be directly relevant to CCN activation 28 and to place tighter constraints on the equilibrium solution compositions required to underpin the development of predictive models.…”

Section: Introductionmentioning

confidence: 99%

Accurate Measurements of Aerosol Hygroscopic Growth over a Wide Range in Relative Humidity

et al. 2016

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Using a comparative evaporation kinetics approach, we describe a new and accurate method for determining the equilibrium hygroscopic growth of aerosol droplets. The time-evolving size of an aqueous droplet, as it evaporates to a steady size and composition that is in equilibrium with the gas phase relative humidity, is used to determine the time-dependent mass flux of water, yielding information on the vapor pressure of water above the droplet surface at every instant in time. Accurate characterization of the gas phase relative humidity is provided from a control measurement of the evaporation profile of a droplet of know equilibrium properties, either a pure water droplet or a sodium chloride droplet. In combination, and by comparison with simulations that account for both the heat and mass transport governing the droplet evaporation kinetics, these measurements allow accurate retrieval of the equilibrium properties of the solution droplet (i.e., the variations with water activity in the mass fraction of solute, diameter growth factor, osmotic coefficient or number of water molecules per solute molecule). Hygroscopicity measurements can be made over a wide range in water activity (from >0.99 to, in principle, <0.05) on time scales of <10 s for droplets containing involatile or volatile solutes. The approach is benchmarked for binary and ternary inorganic solution aerosols with typical uncertainties in water activity of <±0.2% at water activities >0.9 and ∼±1% below 80% RH, and maximum uncertainties in diameter growth factor of ±0.7%. For all of the inorganic systems examined, the time-dependent data are consistent with large values of the mass accommodation (or evaporation) coefficient (>0.1).

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Exploring the complexity of aerosol particle properties and processes using single particle techniques

Cited by 338 publications

References 241 publications

A new electrodynamic balance (EDB) design for low-temperature studies: application to immersion freezing of pollen extract bioaerosols

A new electrodynamic balance (EDB) design for low-temperature studies: application to immersion freezing of pollen extract bioaerosols

Deviations from Plane-Wave Mie Scattering and Precise Retrieval of Refractive Index for a Single Spherical Particle in an Optical Cavity

Accurate Measurements of Aerosol Hygroscopic Growth over a Wide Range in Relative Humidity

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