AVS 62nd International Symposium & Exhibition
    Atom Probe Tomography Focus Topic Monday Sessions
       Session AP+AS-MoA

Paper AP+AS-MoA4
Chemical Imaging of Atmospheric Aerosols using Atom Probe Tomography and Multi-Modal Characterization

Monday, October 19, 2015, 3:20 pm, Room 230A

Session: Current and New Research Fields for Applications of Atom Probe Tomography
Presenter: Jia Liu, Pacific Northwest National Laboratory
Authors: J. Liu, Pacific Northwest National Laboratory
M.I. Nandasiri, Pacific Northwest National Laboratory
L. Gordon, Pacific Northwest National Laboratory
G. Kulkarni, Pacific Northwest National Laboratory
V. Shutthanandan, Pacific Northwest National Laboratory
S.A. Thevuthasan, Qatar Environment and Energy Research Institute, Qatar
A. Devaraj, Pacific Northwest National Laboratory
Correspondent: Click to Email
Global climate is significantly dictated by small particulates in the atmosphere known as aerosols. These atmospheric aerosol particles when subjected to certain humidity and temperature conditions can induce heterogeneous ice nucleation, which is directly sensitive to aerosol surface structure and chemistry. These ice nuclei are the precursors to snow fall and precipitation. Often natural atmospheric aerosols are found to be coated with sulfates and organic molecules. Elucidating the mechanism responsible for ice nucleation on coated or bare atmospheric aerosols requires understanding the structure, composition and chemical state of coated and bare aerosols. At EMSL we are developing a multimodal approach for imaging bare and coated aerosols utilizing a combination of atom probe tomography (APT), imaging X-ray photoelectron spectroscopy (XPS), focused ion beam scanning electron microscopy (FIB-SEM) and transmission electron microscopy (TEM). Imaging XPS provides the composition and chemical state of organic or inorganic elements within the top 5nm of the surface of aerosol particles with a spatial resolution of ~3 µm. FIB-SEM aids in understanding the morphology and porosity of particles both on the surface and sub-surface. TEM provides the atomic scale structural information and laser assisted APT provides sub-nanoscale compositional mapping of aerosols. TEM and APT are sub-single particle analysis techniques and can complement the individual aerosol particle measurements provided by the single particle laser ablation time of flight mass spectrometry (SPLAT). All these techniques provide specific multiscale chemical and structural information about the aerosol particles from the macro- to the atomic-scale. Specific examples from multimodal chemical imaging of mineral dust aerosols coated with varying concentration of sulfuric acid or organics will be presented along with the direct insights gained through this approach for improving ice nucleation parameterizations.