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Surface Formation Pathway of Nitrogen- and Sulfur-Containing Organic Compounds on Ammonium Sulfate

Chen, Jie Ping ; Kisimbiri, George Wandera ; Gladich, Ivan ; Fauré, Nicolas ; Thomson, Erik S. ; Temperton, Robert LU ; Kanji, Zamin A. and Kong, Xiangrui (2025) In Journal of Physical Chemistry A 129(12). p.2922-2931
Abstract

The formation of nitrogen- and sulfur-containing organic compounds (N-Org and S-Org) is important for atmospheric secondary organic aerosol (SOA) production, thereby influencing air quality and global climate. However, the mechanisms underlying N-Org and S-Org formation on aerosol particle surfaces are poorly understood due to the limited availability of surface-sensitive analytical techniques. This study investigates the surface interactions of glyoxal (GL), a known SOA precursor, with ammonium sulfate (NH4)2SO4, under varying relative humidity (RH) conditions, using ambient-pressure X-ray photoelectron spectroscopy (APXPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and molecular... (More)

The formation of nitrogen- and sulfur-containing organic compounds (N-Org and S-Org) is important for atmospheric secondary organic aerosol (SOA) production, thereby influencing air quality and global climate. However, the mechanisms underlying N-Org and S-Org formation on aerosol particle surfaces are poorly understood due to the limited availability of surface-sensitive analytical techniques. This study investigates the surface interactions of glyoxal (GL), a known SOA precursor, with ammonium sulfate (NH4)2SO4, under varying relative humidity (RH) conditions, using ambient-pressure X-ray photoelectron spectroscopy (APXPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and molecular dynamics (MD) simulations. N-Org species, such as imines, a key intermediate in brown carbon (BrC) formation, are identified on the (NH4)2SO4 surface at low RH (≤13.3%). The formed S-Org species cannot be specified due to the difficulties in distinguishing S-Org from inorganic sulfate in the XPS spectra. Elemental ratios on (NH4)2SO4 surface across the entire probing depth show increased S/O and N/O ratios upon GL exposure, indicating the formation of N-Org and S-Org species. NEXAFS measurements further confirm the surface changes of (NH4)2SO4 associated with the adsorption of GL and water. These findings provide compelling evidence of surface-driven N-Org and S-Org formation pathways, demonstrating that heterogeneous reactions on (NH4)2SO4 particle surfaces could be an active source of atmospheric BrC and SOA.

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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry A
volume
129
issue
12
pages
10 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:105001419934
  • pmid:40080451
ISSN
1089-5639
DOI
10.1021/acs.jpca.5c00332
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2025 The Authors. Published by American Chemical Society.
id
a996e53c-e777-4d70-a551-18863440b41b
date added to LUP
2025-08-22 13:34:38
date last changed
2025-08-23 03:00:03
@article{a996e53c-e777-4d70-a551-18863440b41b,
  abstract     = {{<p>The formation of nitrogen- and sulfur-containing organic compounds (N-Org and S-Org) is important for atmospheric secondary organic aerosol (SOA) production, thereby influencing air quality and global climate. However, the mechanisms underlying N-Org and S-Org formation on aerosol particle surfaces are poorly understood due to the limited availability of surface-sensitive analytical techniques. This study investigates the surface interactions of glyoxal (GL), a known SOA precursor, with ammonium sulfate (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub>, under varying relative humidity (RH) conditions, using ambient-pressure X-ray photoelectron spectroscopy (APXPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and molecular dynamics (MD) simulations. N-Org species, such as imines, a key intermediate in brown carbon (BrC) formation, are identified on the (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> surface at low RH (≤13.3%). The formed S-Org species cannot be specified due to the difficulties in distinguishing S-Org from inorganic sulfate in the XPS spectra. Elemental ratios on (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> surface across the entire probing depth show increased S/O and N/O ratios upon GL exposure, indicating the formation of N-Org and S-Org species. NEXAFS measurements further confirm the surface changes of (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> associated with the adsorption of GL and water. These findings provide compelling evidence of surface-driven N-Org and S-Org formation pathways, demonstrating that heterogeneous reactions on (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> particle surfaces could be an active source of atmospheric BrC and SOA.</p>}},
  author       = {{Chen, Jie Ping and Kisimbiri, George Wandera and Gladich, Ivan and Fauré, Nicolas and Thomson, Erik S. and Temperton, Robert and Kanji, Zamin A. and Kong, Xiangrui}},
  issn         = {{1089-5639}},
  language     = {{eng}},
  month        = {{03}},
  number       = {{12}},
  pages        = {{2922--2931}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Journal of Physical Chemistry A}},
  title        = {{Surface Formation Pathway of Nitrogen- and Sulfur-Containing Organic Compounds on Ammonium Sulfate}},
  url          = {{http://dx.doi.org/10.1021/acs.jpca.5c00332}},
  doi          = {{10.1021/acs.jpca.5c00332}},
  volume       = {{129}},
  year         = {{2025}},
}