A236-09
Studying the Vibrational Signatures of Ice Templating Processes at Sea Spray Aerosols Interfaces via Ab Initio Molecular Dynamics

Wednesday, 16 December 2020: 09:19
Virtual
Laura McCaslin, Sandia National Laboratories, Combustion Research Facility, Livermore, CA, United States, Maria Vazquez de Vasquez, Ohio State University Main Campus, Chemistry & Biochemistry, Columbus, OH, United States, Kimberly A. Carter-Fenk, Ohio State University Main Campus, Chemistry & Biochemistry, Columbus, United States and Heather C Allen, Ohio State University Main Campus, Chemistry and Biochemistry, Columbus, OH, United States
Recorded Presentation
Abstract:
In colder regions, atmospheric ice nucleation has a profound impact on the radiative properties of clouds and their precipitation patterns. Atmospheric aerosol particles derived from sea spray (SSA) play an important role in ice nucleation processes over remote oceans of the Southern Hemisphere. (1) However, current global climate models do not correctly account for the effects of SSA ice nucleation. (2) While the favorable ice nucleation properties of alcohol monolayers have been understood for the past 30 years, recent evidence suggests that at cooler temperatures, long chain fatty acids originating in the sea surface microlayer are active in ice nucleation processes, though short chain fatty acids and polysaccharides may also have ice nucleation capabilities. (3, 4) These surprising results indicate that additional study on fatty acid monolayers of sea spray aerosols is necessary to understanding the physical mechanisms of ice nucleation. In this work, long chain alcohol and carboxylic acid monolayers on water surfaces are studied via Infrared Reflection-Absorption Spectroscopy at 21 °C and 0 °C to investigate spectral signals of the ice templating process. Two main features are observed in the OH stretching region of the spectra at ~3200 and ~3600 cm-1. In order to identify the underlying vibrational structure of these bands and their temperature dependence, the following cluster systems are studied: propanol + 6H2O and propionic acid + 10H2O using a polarizable continuum model (PCM) to simulate bulk water. Infrared (IR) spectra are computed from ab initio molecular dynamics (AIMD) calculations and the underlying vibrational structure of IR features is analyzed.

  1. S. M. Burrows, C. Hoose, U. Pöschl, M. G. Lawrence, Atmos. Chem. Phys. (2013), doi:10.5194/acp-13-245-2013.
  2. D. T. McCoy, D. L. Hartmann, M. D. Zelinka, P. Ceppi, D. P. Grosvenor, J. Geophys. Res. (2015), doi:10.1002/2015JD023603.
  3. C. S. Mccluskey et al., J. Atmos. Sci. (2018), doi:10.1175/JAS-D-17-0155.1.
  4. P. J. DeMott et al., Environ. Sci. Process. Impacts (2018), doi:10.1039/c8em00386f.
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