Abstract View
Single Particle Analysis to Study Heterogeneous Oxidative Aging of Aerosols
RAVLEEN KAUR KOHLI, James F. Davies, University of California, Riverside
Abstract Number: 344
Working Group: Aerosol Chemistry
Abstract
Aerosols are a major component of Earth’s atmosphere and affect the formation and optical properties of clouds, absorb and scatter solar radiation, provide surfaces on which chemistry can occur, and adversely impact air quality and human health. The composition of atmospheric aerosol particles comprises of a wide range of organic compounds. Due to aerosols’ incredible composition along with supporting conditions in the atmosphere, their properties and composition continuously transform as a result of various physical processes (evaporation/condensation) and chemical reactions (in/on particles).
A major area of focus in present day atmospheric research is to understand and predict how aerosol particles evolve in the atmosphere due to various heterogeneous oxidation processes, involving ozone (O3) and radicals such as OH· and NO3·. This has led to extensive explorations of their physical and chemical properties through the development of various single particle and ensemble measurement techniques. While these individual techniques have been developed to independently measure specific properties, there remains a need to allow a complete physicochemical characterization of an aerosol sample for developing the connection between its physical properties with evolving composition.
In this work we discuss the development of an experimental platform that couples a linear quadrupole electrodynamic balance (LQ-EDB) with paper spray mass spectrometry (PS-MS) to precisely measure the physicochemical properties of levitated aerosol particles. This technique allows us to simulate heterogeneous reactions happening in atmosphere, such as ozonolysis and OH-initiated oxidation, on single levitated particles and precisely measure their physical and optical properties as a function of their evolving composition with extent of reaction. Preliminary measurements on model aerosol samples demonstrate that the LQ-EDB-PS-MS technique is an effective tool for real-time qualitative and quantitative analysis of complex aerosol particles undergoing chemical transformations.