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Analytical Chemistry Seminar – Prof. Alexei Tivanski, University of Iowa
October 15, 2020 @ 12:05 pm - 1:05 pm
Prof. Alexei Tivanski
University of Iowa
Analytical Chemistry, Seminar
ANALYTICAL CHEMISTRY SEMINAR “RECENT ADVANCES IN SINGLE PARTICLE ATOMIC FORCE MICROSCOPY”
Depending on the source, relative humidity and temperature, aerosols can have different compositional, morphological, and viscoelastic properties. Currently, large uncertainties remain over our ability to accurately predict the overall aerosol effect on the climate and environment. One reason originates from significant particle-to-particle variability of the aerosol’s properties and the inherent size limitations present in current experimental techniques towards studies of submicrometer-sized particles. Studies that determine these properties at a single particle level with nanometer-level spatial resolution can provide important information on the behavior of aerosols over a broad range of applications including atmospheric and materials science. Herein, we present several atomic force microscopy (AFM) based methodologies developed and validated on a series of model aerosol systems that permit direct quantification of the 3D morphology, water uptake growth factor, physical phase state, viscoelastic properties and surface tension of aerosol particles on a single particle basis as a function of relative humidity. We establish quantitative framework using AFM force spectroscopy towards differentiation of the physical phase states of individual particles and quantification of the surface tension of individual deliquesced droplets without prior knowledge of their chemical identity. Furthermore, we introduce the ability to semi-quantitatively assess the phase states of individual substrate deposited particles based on a relatively fast height imaging, irrespective of the microscopy technique used, which can then subsequently be further validated by more quantitative AFM force spectroscopy. The methods are general and can be applied to a wide range of nano- and micro-dimensional materials where the quantification of the physical phase state and viscoelastic properties under various environmental conditions (e.g. variable relative humidity, temperature) is required.
FOR MORE INFORMATION, CONTACT: LIV WEST AT OBWEST@WISC.EDU