Abstract View
Understanding the Physicochemical Evolution of Levitated Particles using Linear Quadrupole Electrodynamic Balance Coupled with Paper Spray Mass Spectrometry
RAVLEEN KAUR KOHLI, James F. Davies, University of California, Riverside
Abstract Number: 717
Working Group: Aerosol Standards
Abstract
Aerosols are an important component of earth’s atmosphere which influence cloud properties, climate, air quality and health. Due to aerosols’ wide composition range along with reactive environmental conditions, their chemical composition and hence properties are continuously evolving as a result of various physicochemical processes (like heterogeneous reactions, photochemical transformations, and evaporation) happening in/on the particles. Understanding the physicochemical evolution of these particles is crucial to predict their role and impacts in the atmosphere.
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 chemically evolving multi-component levitated aerosol particles. In terms of experimental setup, an array of micrometer sized droplets is levitated in LQ-EDB. The light scattering technique is employed to determine physical properties (like size and RI) using Mie resonance spectroscopy which is then followed by compositional measurements of individual particles using high resolution MS.
Measurements of the evaporation kinetics of two volatile n-ethylene glycols, triethylene glycol and tetraethylene glycol in their binary and ternary mixtures, were made in real-time under dry conditions to understand and relate the evolving size with chemical composition. These measurements were then extended to explore the influence of various humidity conditions on the evaporation kinetics. It is demonstrated that both size and composition evolution follow the expected trend with each other and also when compared against evaporation model predictions. Finally, our results demonstrate that the LQ-EDB-MS platform can accurately and precisely measure the time-dependent physical properties and compositional changes, yielding broad capabilities for studying chemical aging in suspended particles.