A Cross-laboratory Comparison Study of Titan Haze Analogs: Surface Energy II
5 affiliations
- 1University of Texas at San Antonio
- 2Johns Hopkins University
- 3NASA Ames Research Center
- 4University of Northern Iowa
- 5University of California Santa Cruz
Abstract
The organic haze particles on Titan play important roles in atmospheric cloud formation and aerosol–lake interactions. These processes are strongly influenced by the surface energy of the haze particles, which controls cohesion and wetting behavior. This study presents a comparative analysis of 32 laboratory-produced haze analog samples (“tholins”) synthesized across three laboratories. Using contact angle measurements, we determine the total surface energy and its dispersive and polar components for all samples, systematically evaluating the effects of substrate choice, air exposure, initial N ₂ /CH ₄ gas mixture, and experimental setup. We find that tholin samples exhibit minimal substrate dependence, whereas exposure to ambient air substantially modifies the surface chemistry, altering the balance between dispersive and polar components. Thus, future Titan-relevant surface property measurements may use any substrate but must keep samples pristine. Surface energies vary weakly across methane concentrations, from 1% to 10% CH ₄ in N ₂ , indicating that Titan’s hazes formed at different altitudes should exhibit broadly similar cohesiveness. In contrast, experimental conditions such as gas exposure time and energy source produce the dominant differences in surface energy, driven largely by variations in polar components. Despite these differences, tholin samples exhibit high dispersive components, implying that Titan’s hazes should act as efficient cloud condensation nuclei for hydrocarbon clouds and should generally sink into Titan’s lakes. Given observed ethane ice clouds, we conclude that cold plasma tholins may be better physical analogs for Titan’s hazes than samples produced with far-UV irradiation, though intrinsic surface energies of UV tholins remain uncertain due to film thickness limitations.
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BibTeX
@article{austin2026crosslaboratory,
title = {{A Cross-laboratory Comparison Study of Titan Haze Analogs: Surface Energy II}},
author = {Eric C. Austin and Xinting 馨婷 Yu 余 and Chao He and Cara Pesciotta and Ella Sciamma-O’Brien and Joshua A. Sebree and Jose Raul Montes-Bojorquez and Adis Husić and Erik White and Christopher R. Bond and Sarah M. Hörst and Farid Salama and Patricia McGuiggan},
journal = {The Planetary Science Journal},
year = {2026},
month = oct,
doi = {10.3847/psj/aea60b},
url = {https://iopscience.iop.org/article/10.3847/PSJ/aea60b},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - A Cross-laboratory Comparison Study of Titan Haze Analogs: Surface Energy II
AU - Eric C. Austin
AU - Xinting 馨婷 Yu 余
AU - Chao He
AU - Cara Pesciotta
AU - Ella Sciamma-O’Brien
AU - Joshua A. Sebree
AU - Jose Raul Montes-Bojorquez
AU - Adis Husić
AU - Erik White
AU - Christopher R. Bond
AU - Sarah M. Hörst
AU - Farid Salama
AU - Patricia McGuiggan
PY - 2026
DA - 2026/10/01
JO - The Planetary Science Journal
DO - 10.3847/psj/aea60b
UR - https://iopscience.iop.org/article/10.3847/PSJ/aea60b
AB - The organic haze particles on Titan play important roles in atmospheric cloud formation and aerosol–lake interactions. These processes are strongly influenced by the surface energy of the haze particles, which controls cohesion and wetting behavior. This study presents a comparative analysis of 32 laboratory-produced haze analog samples (“tholins”) synthesized across three laboratories. Using contact angle measurements, we determine the total surface energy and its dispersive and polar components for all samples, systematically evaluating the effects of substrate choice, air exposure, initial N ₂ /CH ₄ gas mixture, and experimental setup. We find that tholin samples exhibit minimal substrate dependence, whereas exposure to ambient air substantially modifies the surface chemistry, altering the balance between dispersive and polar components. Thus, future Titan-relevant surface property measurements may use any substrate but must keep samples pristine. Surface energies vary weakly across methane concentrations, from 1% to 10% CH ₄ in N ₂ , indicating that Titan’s hazes formed at different altitudes should exhibit broadly similar cohesiveness. In contrast, experimental conditions such as gas exposure time and energy source produce the dominant differences in surface energy, driven largely by variations in polar components. Despite these differences, tholin samples exhibit high dispersive components, implying that Titan’s hazes should act as efficient cloud condensation nuclei for hydrocarbon clouds and should generally sink into Titan’s lakes. Given observed ethane ice clouds, we conclude that cold plasma tholins may be better physical analogs for Titan’s hazes than samples produced with far-UV irradiation, though intrinsic surface energies of UV tholins remain uncertain due to film thickness limitations.
SN - 2632-3338
ER -