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

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Accurate Measurements of Aerosol Hygroscopic Growth Over a Wide Range in Relative Humidity. / Rovelli, Grazia; Miles, Rachael E H; Reid, Jonathan P.; Clegg, Simon L.

In: Journal of Physical Chemistry A, Vol. 120, No. 25, 30.06.2016, p. 4376-4388.

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Rovelli, Grazia ; Miles, Rachael E H ; Reid, Jonathan P. ; Clegg, Simon L. / Accurate Measurements of Aerosol Hygroscopic Growth Over a Wide Range in Relative Humidity. In: Journal of Physical Chemistry A. 2016 ; Vol. 120, No. 25. pp. 4376-4388.

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@article{6169dd6d641b465ea1072b41efd9ddf4,
title = "Accurate Measurements of Aerosol Hygroscopic Growth Over a Wide Range in Relative Humidity",
abstract = "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 vapour 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 timescales 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 timedependent data are consistent with large values of the mass accommodation (or evaporation) coefficient (>0.1).",
author = "Grazia Rovelli and Miles, {Rachael E H} and Reid, {Jonathan P.} and Clegg, {Simon L.}",
year = "2016",
month = "6",
day = "30",
doi = "10.1021/acs.jpca.6b04194",
language = "English",
volume = "120",
pages = "4376--4388",
journal = "Journal of Physical Chemistry A",
issn = "1089-5639",
publisher = "American Chemical Society",
number = "25",

}

RIS - suitable for import to EndNote

TY - JOUR

T1 - Accurate Measurements of Aerosol Hygroscopic Growth Over a Wide Range in Relative Humidity

AU - Rovelli, Grazia

AU - Miles, Rachael E H

AU - Reid, Jonathan P.

AU - Clegg, Simon L.

PY - 2016/6/30

Y1 - 2016/6/30

N2 - 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 vapour 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 timescales 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 timedependent data are consistent with large values of the mass accommodation (or evaporation) coefficient (>0.1).

AB - 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 vapour 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 timescales 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 timedependent data are consistent with large values of the mass accommodation (or evaporation) coefficient (>0.1).

UR - http://www.scopus.com/inward/record.url?scp=84976907522&partnerID=8YFLogxK

U2 - 10.1021/acs.jpca.6b04194

DO - 10.1021/acs.jpca.6b04194

M3 - Article

VL - 120

SP - 4376

EP - 4388

JO - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

IS - 25

ER -