Eleanor C. Browne
· Associate Professor • Institute Fellow, CIRESVerifiedUniversity of Colorado Boulder · Chemistry
Active 2005–2026
About
Eleanor C. Browne is an Associate Professor in the Department of Chemistry at the University of Colorado Boulder and an Institute Fellow at the CIRES (Cooperative Institute for Research in Environmental Sciences). Her research focuses on understanding the mechanisms of aerosol formation and growth, which are critical for constraining a planet’s energy budget and understanding atmospheric processes. She employs a combination of field measurements, laboratory experiments, modeling, and instrument/method development to investigate new particle formation and growth, particularly at the Department of Energy Atmospheric Radiation Measurement Southern Great Plains research station, with an emphasis on atmospheric chemistry in agricultural regions. Her work extends to planetary atmospheres, where she studies the composition and formation of organic aerosols in atmospheres similar to Saturn's moon Titan and Earth's Archean Eon, exploring how trace gases influence aerosol properties and their potential as biosignatures. Additionally, she researches organosilicon chemistry, focusing on the atmospheric oxidation of siloxanes and their environmental fate. A significant aspect of her work involves developing new instruments and methods for measuring atmospheric constituents, including reagent ions for mass spectrometry and data visualization techniques. Her contributions have been recognized with awards such as the American Society for Mass Spectrometry Research Award (2019), the Provost Faculty Achievement Award (2022), and the ACS Environmental Au Rising Star Award (2022).
Research topics
- Photochemistry
- Environmental chemistry
- Organic chemistry
- Chemistry
- Materials science
Selected publications
ACS Earth and Space Chemistry · 2026-02-23 · 1 citations
articleCorrespondingThe Earth’s atmosphere during the Archean eon (4.0–2.5 billion years ago) likely contained an intermittent organic haze. This haze, formed through photochemical reactions in the atmosphere, is mostly composed of molecular nitrogen (N2), carbon dioxide (CO2), and methane (CH4) and could have served as a protective layer shielding Earth’s surface from harmful ultraviolet (UV) radiation. However, the chemical composition of these organic haze particles remains poorly understood, due in part to the lack of knowledge of how trace atmospheric constituents, such as sulfur gases from volcanic activity, affect haze chemistry. Determining organic/inorganic S speciation from atmospheric chemistry is important for interpreting Earth’s geologic record. Here, we chemically characterized organic haze particles that form under Archean-relevant atmospheric conditions (0.1% CH4, 5 ppm of H2S) with either 0.5 or 0.1% CO2 in a N2 background by using hydrophilic interaction liquid chromatography coupled to electrospray ionization and high-resolution quadrupole time-of-flight mass spectrometry (HILIC/ESI-HR-QTOFMS). HILIC/ESI-HR-QTOFMS was able to achieve chromatographic resolution of isomers and provide accurate molecular formula determinations of organic haze particulate constituents. We show how the relative abundances of 121 compounds vary between these two CO2 concentrations. The observed molecules fall into 6 categories of elemental composition (i.e., CHN, CHS, CHNS, CHNO, CHOS, and CHNOS). Compounds composed of CHN, CHS, and CHNS formed preferentially under low-CO2 conditions and CHNOS molecules under high-CO2 conditions. Important biomolecules such as urea were detected, highlighting the fact that atmospheric photochemistry may have been an important source of complex organic molecules that could help the proliferation of early life.
UNC Libraries · 2026-02-20
articleOpen accessFine aerosols are critical in influencing planetary climate and surface conditions, and thus, understanding the sources and chemical composition of aerosols is vital for constraining the habitability potential of a planet. Molecular nitrogen (N2), methane (CH4), carbon dioxide (CO2), and sulfur gases (e.g., hydrogen sulfide (H2S) and sulfur dioxide (SO2)) are common components of planetary atmospheres that can undergo atmospheric photochemical reactions to produce both inorganic and organic aerosols. Recent studies have shown that organic aerosol production is closely tied to the presence of H2S, potentially through the formation of organosulfur compounds. However, molecular-level speciation of organosulfur compounds is lacking, thus limiting our understanding of what, if any, implications these compounds hold for the early beginnings of life or the planetary climate. Here, we chemically characterized 60 organosulfur compounds in aerosols produced during laboratory analog experiments using an irradiated mixture of 0.5% CO2 with 0.1% CH4 and 5 ppm of H2S in a N2 background by hydrophilic interaction liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (HILIC/ESI-HR-QTOFMS). Accurate mass and tandem mass spectrometry measurements provided information regarding sulfur functionality and the overall chemical structure. Sulfur was found in multiple oxidation states within functional groups such as sulfates, sulfonic acids, sulfites, sulfinic acids, and thiols. We found that five simple organosulfur species, including methyl sulfate, ethyl sulfate, methanesulfonic acid, ethanesulfonic acid, and isethionic acid, contributed 6.2–7.9% of the total aerosol mass. These results suggest that organosulfur could have played a significant role in the Archean sulfur cycle.
An Archean atmosphere rich in sulfur biomolecules
Proceedings of the National Academy of Sciences · 2025-12-01 · 2 citations
articleOpen accessSenior authorCorrespondingThe abiotic production of sulfur-containing biomolecules under mild and globally relevant conditions has been an elusive endeavor in prebiotic chemistry experiments. As a result, a disconnect has emerged between understanding the origins of life and the later stages of biological evolution; the former potentially occurred independent of sulfur while the latter is universally dependent on it. Here, we demonstrate that planetary organic haze chemistry produces a suite of sulfur biomolecules including cysteine, coenzyme M, taurine, and potentially methionine and homocysteine. These compounds may form high in the atmosphere and subsequently deposit to early surface environments in sufficient amounts to support a budding global biosphere. Our findings thus challenge long-standing assumptions that sulfur biomolecules such as cysteine must have been biological "inventions."
Environmental Science Atmospheres · 2025-01-01 · 1 citations
articleOpen accessSenior authorCorrespondingDecamethylcyclopentasiloxane is emitted in populated areas and oxidized to form the siloxanol. Small amounts of the siloxanol partition to the particle phase via adsorption onto ammonium sulfate seeds and via absorption into dioctyl sebacate seeds.
Astrobiology · 2025-06-01 · 3 citations
articleAtmospheric organic hazes are widespread across various planetary bodies and have significant effects on both the surface and atmosphere. In this study, we investigate the optical and hygroscopic properties of organic hazes formed through photochemical processes. The hazes were generated from the irradiation of mixtures that contained molecular nitrogen (N 2 ), methane (CH 4 ), hydrogen sulfide (H 2 S), and varying amounts of carbon dioxide (CO 2 ) to mimic early Earth-like conditions. In the absence of CO 2 , the photochemical haze absorbed radiation at 405 nm. In contrast, the incorporation of CO 2 into the precursor gas mixtures resulted in hazes with reduced absorption at 405 nm. This decrease in absorption was due to the formation of non-absorbing inorganic salts and/or a change in organic composition; however, the exact composition is not fully known. Further, we observed that these hazes exhibited varying tendencies to uptake water, with non-CO 2 hazes showing no water uptake, while CO 2 hazes could absorb water and increase in size. Consequently, under humid conditions, the increased size of the haze enhanced its ability to scatter light and would thus promote cooling of a planetary atmosphere. Both the change in refractive indices and the increased hygroscopicity would contribute to greater cooling effects with higher CO 2 levels. In addition, the ability of the haze to uptake water would facilitate the particles acting as cloud condensation nuclei, potentially leading to the wet deposition of nutrients to a planet’s surface that could help facilitate the emergence of life.
ACS Environmental Au · 2025-06-05
articleOpen accessSenior authorCorresponding. MCCP diel behavior is partially explained by gas-particle partitioning with implications for MCCP transport and lifetimes.
Medium-Chain Chlorinated Paraffins Measurements, SGP GIF, May 2023
OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 2025-01-01
datasetOpen accessSenior authorThis dataset contains measurements of medium-chain chlorinated paraffins (MCCPs) at 5-minute time resolution. The 6 most abundant ones are reported as well as the sum of all MCCPs measured. MCCPs were measured using a nitrate chemical ionization mass spectrometer at the ARM Southern Great Plains Guest Instrumentation Facility. Reported concentrations represent lower limit concentrations.
ACS Earth and Space Chemistry · 2025-02-19 · 5 citations
articleCorrespondingFine aerosols are critical in influencing planetary climate and surface conditions, and thus, understanding the sources and chemical composition of aerosols is vital for constraining the habitability potential of a planet. Molecular nitrogen (N2), methane (CH4), carbon dioxide (CO2), and sulfur gases (e.g., hydrogen sulfide (H2S) and sulfur dioxide (SO2)) are common components of planetary atmospheres that can undergo atmospheric photochemical reactions to produce both inorganic and organic aerosols. Recent studies have shown that organic aerosol production is closely tied to the presence of H2S, potentially through the formation of organosulfur compounds. However, molecular-level speciation of organosulfur compounds is lacking, thus limiting our understanding of what, if any, implications these compounds hold for the early beginnings of life or the planetary climate. Here, we chemically characterized 60 organosulfur compounds in aerosols produced during laboratory analog experiments using an irradiated mixture of 0.5% CO2 with 0.1% CH4 and 5 ppm of H2S in a N2 background by hydrophilic interaction liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (HILIC/ESI-HR-QTOFMS). Accurate mass and tandem mass spectrometry measurements provided information regarding sulfur functionality and the overall chemical structure. Sulfur was found in multiple oxidation states within functional groups such as sulfates, sulfonic acids, sulfites, sulfinic acids, and thiols. We found that five simple organosulfur species, including methyl sulfate, ethyl sulfate, methanesulfonic acid, ethanesulfonic acid, and isethionic acid, contributed 6.2–7.9% of the total aerosol mass. These results suggest that organosulfur could have played a significant role in the Archean sulfur cycle.
Chemical Characterization of Organosulfur Compounds in Aerosols from Archean-Analog Photochemistry: Insights from Liquid Chromatography and High-Resolution Tandem Mass Spectrometry
Open MIND · 2025-01-01
articleFine aerosols are critical in influencing planetary climate and surface conditions, and thus, understanding the sources and chemical composition of aerosols is vital for constraining the habitability potential of a planet. Molecular nitrogen (N2), methane (CH4), carbon dioxide (CO2), and sulfur gases (e.g., hydrogen sulfide (H2S) and sulfur dioxide (SO2)) are common components of planetary atmospheres that can undergo atmospheric photochemical reactions to produce both inorganic and organic aerosols. Recent studies have shown that organic aerosol production is closely tied to the presence of H2S, potentially through the formation of organosulfur compounds. However, molecular-level speciation of organosulfur compounds is lacking, thus limiting our understanding of what, if any, implications these compounds hold for the early beginnings of life or the planetary climate. Here, we chemically characterized 60 organosulfur compounds in aerosols produced during laboratory analog experiments using an irradiated mixture of 0.5% CO2 with 0.1% CH4 and 5 ppm of H2S in a N2 background by hydrophilic interaction liquid chromatography coupled to electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (HILIC/ESI-HR-QTOFMS). Accurate mass and tandem mass spectrometry measurements provided information regarding sulfur functionality and the overall chemical structure. Sulfur was found in multiple oxidation states within functional groups such as sulfates, sulfonic acids, sulfites, sulfinic acids, and thiols. We found that five simple organosulfur species, including methyl sulfate, ethyl sulfate, methanesulfonic acid, ethanesulfonic acid, and isethionic acid, contributed 6.2–7.9% of the total aerosol mass. These results suggest that organosulfur could have played a significant role in the Archean sulfur cycle.
NO, NO2. NOx measurements; SGP GIF; April 2022
OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 2024-01-01
articleOpen access1st authorCorrespondingThis file contains measurements of nitric oxide (NO), nitrogen dioxide (NO2), and nitrogen oxides (NOx = NO + NO1). Measurements were made using a Teledyne NO-NOx Analyzer Model T200UP. Zeros were conducted daily and calibrations were completed at the end of the campaign. The instrument was located at the Atmospheric Radiation Measurement Southern Great Plains Guest Instrumentation Facility and measured from April 9, 2022 to May 6, 2022. The file is in ICARTT format.
Recent grants
Constraining the Degradation Pathways of Siloxanes in the Atmosphere
NSF · $341k · 2018–2022
NSF · $217k · 2021–2025
Frequent coauthors
- 98 shared
R. C. Cohen
University of California, Berkeley
- 69 shared
K.‐E. Min
State Key Laboratory For Conservation and Utilization of Subtropical Agro-Bioresources
- 44 shared
P. J. Wooldridge
University of California, Berkeley
- 43 shared
Sally E. Pusede
University of Virginia
- 42 shared
A. H. Goldstein
- 40 shared
B. W. LaFranchi
- 36 shared
Margaret A. Tolbert
University of Colorado Boulder
- 36 shared
W. H. Brune
Pennsylvania State University
Education
- 2012
Ph.D.
University of California, Berkeley
- 2015
Other
Massachusetts Institute of Technology
Awards & honors
- American Society for Mass Spectrometry Research Award (2019)
- Provost Faculty Achievement Award (2022)
- ACS Environmental Au Rising Star Award (2022)
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