10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Dynamics of Liquid-Liquid Phase-Separation Using Spatial-Resolved Raman Spectroscopy of a Laser-Trapped Mixed Organic-Organic Aerosol Droplet
AIMABLE KALUME, Chuji Wang, Joshua Santarpia, Patricio Piedra, Yong-Le Pan, U.S. Army Research Laboratory
Abstract Number: 218 Working Group: Aerosol Chemistry
Abstract Aerosols play key role in different areas including atmospheric processes, combustion, drug designing, household sprays, etc. Building upon our recent studies of characterizing a single-particle by laser-trapping Raman spectroscopy, a multicomponent organic-organic microdroplet from a mixture of diethyl phthalate (DEPh) and glycerol (1:1 initial volume ratio) suspended in air was investigated. Initial position-resolved examination of the droplet shows a gradient concentration at different positions within the droplet, suggesting phase separation. An extensive Raman spectroscopy measurement combining spatial and temporal resolutions, revealed the phase separation and the evaporation dynamics from the droplet. The DEPh–glycerol droplet presents a typical core-shell morphology, with a glycerol-rich core and DEPh highly concentrated within the outer layer. The reported approach provides a direct experimental observation of the morphological structure and the chemical microcomposition of a multicomponent microdroplet suspended in the ambient air. This technique opens new doors in probing surface enhanced phenomena, such as potential chemical reactions taking place at the interface of aerosols with the chemicals in the surrounding microenvironment.