Properties of Aerosol Components: laboratory studies and predictions

  • Supervisors: Prof. Gordon McFiggans
    Dr David Topping
    Dr James Allan
    Prof. Carl Percival , Prof. Hugh Coe (UoM, SEAES)
  • External Supervisors:

  • Contact:

    Gordon McFiggans g.mcfiggans@manchester.ac.uk

  • CASE Partner: No

Application deadline: 3 February 2017

Introduction:

Atmospheric aerosol particles may significantly impact on both on human health and global climate; both areas of substantial current interest. The effects will largely be determined by their physico-chemical properties. For example, the intrinsic ability of an aerosol particle to act as a cloud droplet depends entirely on its affinity for water and on its surface tension. Within the Centre for Atmospheric Sciences, we have been developing a range of analytical techniques to probe the properties of the likely components of the atmospheric aerosol. There may be many hundreds or thousands of organic compounds within an aerosol population. These will be mixed with the major inorganic components, the resulting composition largely determining their atmospheric impacts. We have the capability to measure the vapour pressure, viscosity, surface tension, surface pressure and water activity of pure components, their aqueous solutions and mixtures. Most recently we have developed the capability to directly measure the amount of semi-volatile material in both gaseous and particulate phases. By linking measurements of the properties of these materials to their measured phase partitioning, it is possible to test numerical descriptions of processes used in atmospheric models

Project Summary:

This PhD will involve unravelling the properties of multicomponent mixtures determined by the properties of the individual components or individual particles. These can include i) measurement of the evaporation of the coatings of individual particles containing black carbon, ii) measurement of the vapour pressures of pure components and their mixtures (see http://www.cas.manchester.ac.uk/resactivities/atmosphericchemistry/KEMS/index.html) or iii) the partitioning of semi-volatile components between gases and particles using a new calibration capability for our state-of-the-science chemical ionisation mass spectroscopy (CIMS) instrument with novel “FIGAERO” particle inlet. In conjunction with making these measurements, the successful applicant will examine, evaluate and use a range of interpretive tools to predict the behaviour and impacts of atmospheric aerosol. Some of these can be found on our UManSysProp property prediction website (http://umansysprop.seaes.manchester.ac.uk/).

References:

1. Booth et al., Design and construction of a simple Knudsen Effusion Mass Spectrometer (KEMS) system for vapour pressure measurements of low volatility organics, Atmos. Meas. Tech., 2, 355-361, 2009.

2. O’Meara et al., An assessment of vapour pressure estimation methods, Physical Chemistry Chemical Physics, doi:10.1039/c4cp00857j, 2014.

3. Topping and McFiggans, Tight coupling of particle size, number and composition in atmospheric cloud droplet activation, Atmos. Chem. Phys., 12, 3253-3260, doi:10.5194/acp-12-3253-2012, 2012.

4. Topping et al., Cloud droplet number enhanced by co-condensation of organic vapours, Nature Geoscience, 6, 443-446, doi:10.1038/ngeo1809, 2013.

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