10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Anatomy of Single Airborne Aerosol Particle Using Laser-trapped Submicron Position-resolved Temporal Raman Spectra
Aimable Kalume, Chuji Wang, Joshua Santarpia, YONG-LE PAN, U.S. Army Research Laboratory, Adelphi, MD
Abstract Number: 210 Working Group: Instrumentation
Abstract The study of various molecules located in different positions within a micro-sized particle in its natural phase is essential to a deeper understanding the functions of these molecules, such as the reaction of DNA, RNA, and protein molecules within a cell in buffer solution or different molecules within an airborne aerosol particle freely suspended in the atmosphere as they respond to various environments. Here, we present a new method that can measure the time-resolved Raman spectra from multiple sections across a laser-trapped single airborne particle to capture these crucial functions. Submicron resolved (up to 200 nm × 200 nm) temporal Raman spectra from different positions in a laser trapped particle can be obtained. Droplets in super micron size composed of diethyl phthalate (DEPh), glycerol, or their mixture have been used to test the new method. The results directly demonstrated the micro-cavity enhanced effects within a droplet, also the morphology, dynamics of phase-separation and evaporation of the mixed droplet. By inspecting the physical structure of the mixed droplet, we learned that the two liquids quickly separated and formed a core-shell-like morphology, in which the glycerol was mostly concentrated in the core, and the DEPh dominated around the outer layer of the droplet, as the mixed liquid was aerosolized. We also found that DEPh emerged to the surface and evaporated more quickly, then the glycerol evaporated slowly, but both chemicals in their mixed droplet evaporated much faster than that in their own pure droplet forms. This method should supply a powerful tool for monitoring various chemical reactions and understanding molecular functions at different locations within a single cell, spore, or particle in life and atmospheric science.