Title: Size-dependent depositional loss of inorganic, organic, and mixed composition particles to Teflon chamber walls under various environmental and chemical conditions
DOI: 10.1080/02786826.2023.2298219
Publication Year: 2024
Author list: Adrianne Nakagawa, Kelvin H. Bates, and Tran B. Nguyen
Journal Short Name: Aerosol Sci. Technol.
Publisher: Taylor and Francis

Abstract

Corrections for first-order particle losses to Teflon chamber walls are important sources of uncertainty in experimental studies of particle formation and aging. Particle size distributions and environmental factors significantly influence wall loss corrections; thus, it is important to characterize size-dependent particle loss profiles under myriad experimental conditions that may alter deposition rates. This work investigated size-dependent loss coefficients of inorganic (ammonium sulfate, AS), organic (sorbitol, C6H14O6), and mixed composition (ASþsorbitol, 1:1 by mole) particles to a Teflon chamber under varying chamber temperature (20 – 40 C), relative humidity (RH, <10 – 80%), illumination (dark vs. 100% chamber lights), particle water (crystalline vs. deliquesced vs. metastable), and chamber usage history conditions (clean chamber vs. following chemical experiments). It was found that temperature and lights had negligible to minor effects on loss rates for all particles, while RH, particle water, and chamber usage history each had major effects under all tested conditions. Particle wall loss rates were higher under humid than dry conditions, and higher for deliquesced particles than for dry particles at similar RH. Chemical conditions that introduced acidic species to chamber walls the day prior to a wall loss experiment were responsible for uncertainties of up to 50% in wall loss rate profiles, despite recommended chamber flushing regimens. These data suggest that sensitive OA formation or aging experiments may consider obtaining same-day wall loss profiles from the target experiment. Otherwise, size-dependent corrections for particle wall loss should consider particle composition, particle water, RH, wall usage history, and possibly illumination conditions.

Additional Notes