Influence of Non-Polar Amino Acids on the Phase Transitions of Atmospheric Aerosol Particles
Abstract
The fate of aerosol particles in the atmosphere depends in part on their composition, morphology, and phase transitions. Studies of aerosol phase transitions have focused on aerosol particles with organic compounds consisting of C, H, and O atoms, although a substantial fraction of organic compounds contain heteroatoms such as sulfur and nitrogen. In this study, non-polar amino acids were used to study the effect of organonitrogen compounds on the phase transitions of droplets using optical microscopy. The ternary internal mixtures used were composed of ammonium sulfate (AS), a non-polar amino acid, and either 2-methylglutaric acid (2MGA) or 1,2,6-hexanetriol (126HT) (model oxidized organic compounds). The morphology, phase transitions, and spatially resolved chemical composition were characterized using optical and Raman microscopies. A suppression of the separation relative humidity was observed when the concentration of amino acid was more than 50% of the organic compound by weight. For some systems, the amino acid crystallizes, while the oxidized organic compounds and ammonium sulfate undergo liquid-liquid phase separation, yielding a three-phase system. Trends in the efflorescence relative humidity depend on the solubility of the amino acid. These studies are important in understanding the impact of organic-organic interactions as well as organonitrogen compounds on the phase transitions of aerosol particles, which have consequences for heterogeneous chemistry and cloud droplet nucleation in the atmosphere.
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BibTeX
@misc{pitta2026influence,
title = {{Influence of Non-Polar Amino Acids on the Phase Transitions of Atmospheric Aerosol Particles}},
author = {Kiran Reddy Pitta and Kayla N. McCreary and Nahin Ferdousi-Rokib and Timothy M. Raymond and Dabrina D Dutcher and Akua A. Asa-Awuku and Miriam Arak Freedman},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15004101/v3},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15004101/v3},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Influence of Non-Polar Amino Acids on the Phase Transitions of Atmospheric Aerosol Particles
AU - Kiran Reddy Pitta
AU - Kayla N. McCreary
AU - Nahin Ferdousi-Rokib
AU - Timothy M. Raymond
AU - Dabrina D Dutcher
AU - Akua A. Asa-Awuku
AU - Miriam Arak Freedman
PY - 2026
DA - 2026/09/15
PB - ChemRxiv
DO - 10.26434/chemrxiv.15004101/v3
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15004101/v3
AB - The fate of aerosol particles in the atmosphere depends in part on their composition, morphology, and phase transitions. Studies of aerosol phase transitions have focused on aerosol particles with organic compounds consisting of C, H, and O atoms, although a substantial fraction of organic compounds contain heteroatoms such as sulfur and nitrogen. In this study, non-polar amino acids were used to study the effect of organonitrogen compounds on the phase transitions of droplets using optical microscopy. The ternary internal mixtures used were composed of ammonium sulfate (AS), a non-polar amino acid, and either 2-methylglutaric acid (2MGA) or 1,2,6-hexanetriol (126HT) (model oxidized organic compounds). The morphology, phase transitions, and spatially resolved chemical composition were characterized using optical and Raman microscopies. A suppression of the separation relative humidity was observed when the concentration of amino acid was more than 50% of the organic compound by weight. For some systems, the amino acid crystallizes, while the oxidized organic compounds and ammonium sulfate undergo liquid-liquid phase separation, yielding a three-phase system. Trends in the efflorescence relative humidity depend on the solubility of the amino acid. These studies are important in understanding the impact of organic-organic interactions as well as organonitrogen compounds on the phase transitions of aerosol particles, which have consequences for heterogeneous chemistry and cloud droplet nucleation in the atmosphere.
ER -