Chemical heterogeneities in atmospheric organic particles and their implications for aerosol-water interactions
Event details
| Date | 21.07.2011 |
| Hour | 10:15 |
| Speaker | Satoshi Takahama |
| Location | |
| Category | Conferences - Seminars |
Airborne particulate matter have been associated with excess mortality and play an important role in the radiative balance of the atmosphere.
The organic fraction of these particles or aerosols represent one of the largest uncertainties in our ability to quantify atmospheric burdens and climate feedbacks. Among our uncertainties regarding
these aerosols include particle shape and distribution of chemical compounds within individual particles which are implied in models used for prediction of radiative transfer volatility and mass
transfer. In this talk a combination of measurement and modeling techniques describing chemical heterogeneities and their implications for could-forming properties of organic aerosols are presented. The chemical structure of organic and carbonaceous particles collected in six field campaigns in the western hemisphere is probed by image analysis and pattern recognition techniques applied to single particles analyzed by Scanning Transmission X-Ray Microscopy with Near-Edge X-Ray Absorption Fine Structure Spectroscopy. A few observed types include black carbon particles covered by organic and other aqueous-phase components organic clumps found on dust particles particles enriched in carboxylic acids at the surface and inorganic cores encapsulated by organic shells. Quantified coating thicknesses are calculated to have a significant impact on the equilibrium water uptake properties of these particles. Dynamic uptake properties of water vapor onto particle surfaces coated with organic layers are additionally investigated through a series of molecular simulations which allow an atomistic examination of surface-vapor interactions and quantification of mass accommodation coefficients. These findings are placed in context of observed coating thicknesses and formation of cloud droplets from particles containing such coatings.
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Practical information
- General public
- Free
Contact
- Christina Treier