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Main Authors: Husić, Adis, Yu, Xinting, Blase, Ryan C., Patrick, Edward L., Austin, Eric, Whittington, Alan G.
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2604.20057
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author Husić, Adis
Yu, Xinting
Blase, Ryan C.
Patrick, Edward L.
Austin, Eric
Whittington, Alan G.
author_facet Husić, Adis
Yu, Xinting
Blase, Ryan C.
Patrick, Edward L.
Austin, Eric
Whittington, Alan G.
contents The Cassini-Huygens mission detected large negative ions in Titan's ionosphere at pressures as low as $10^{-6}$ torr. These ions ultimately polymerize to form Titan's complex organic haze particles, which are observed throughout the atmosphere and potentially on the surface. Laboratory analogs of these hazes, known as tholins, have been used to study Titan's aerosols; however, most are produced at much higher pressures. The influence of formation pressures on key physical properties -- such as particle size, density, surface energy, and mechanical strength -- remains poorly constrained. These properties govern the haze's aggregation efficiency, radiative behavior, and surface-atmosphere interactions, shaping Titan's climate and surface. To investigate the effects of formation pressure, we generate tholins using a newly developed cold plasma discharge system. A 95% nitrogen and 5% methane gas mixture is exposed to plasma at two pressures, 1 torr and 0.125 torr. For both samples, we measure the production rate, particle size, morphology, density, surface free energy, Young's modulus, and nanoindentation hardness. While particle size, morphology, surface energy, and Young's modulus are similar across both pressures, tholins produced at lower pressure exhibited a threefold lower production rate, but a higher density and nanoindentation hardness. These variations likely reflect pressure-dependent changes in chemical structure, porosity, and mechanical strength. Because Titan's hazes form at much lower pressures than investigated here, actual haze particles are potentially even denser and mechanically stronger than our analogs, with implications for aerosol aggregation, aeolian and fluvial transport, and surface modification on Titan.
format Preprint
id arxiv_https___arxiv_org_abs_2604_20057
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Feeling the Pressure: Effects of Formation Pressure on the Physical Properties of Titan Haze Analogs
Husić, Adis
Yu, Xinting
Blase, Ryan C.
Patrick, Edward L.
Austin, Eric
Whittington, Alan G.
Earth and Planetary Astrophysics
The Cassini-Huygens mission detected large negative ions in Titan's ionosphere at pressures as low as $10^{-6}$ torr. These ions ultimately polymerize to form Titan's complex organic haze particles, which are observed throughout the atmosphere and potentially on the surface. Laboratory analogs of these hazes, known as tholins, have been used to study Titan's aerosols; however, most are produced at much higher pressures. The influence of formation pressures on key physical properties -- such as particle size, density, surface energy, and mechanical strength -- remains poorly constrained. These properties govern the haze's aggregation efficiency, radiative behavior, and surface-atmosphere interactions, shaping Titan's climate and surface. To investigate the effects of formation pressure, we generate tholins using a newly developed cold plasma discharge system. A 95% nitrogen and 5% methane gas mixture is exposed to plasma at two pressures, 1 torr and 0.125 torr. For both samples, we measure the production rate, particle size, morphology, density, surface free energy, Young's modulus, and nanoindentation hardness. While particle size, morphology, surface energy, and Young's modulus are similar across both pressures, tholins produced at lower pressure exhibited a threefold lower production rate, but a higher density and nanoindentation hardness. These variations likely reflect pressure-dependent changes in chemical structure, porosity, and mechanical strength. Because Titan's hazes form at much lower pressures than investigated here, actual haze particles are potentially even denser and mechanically stronger than our analogs, with implications for aerosol aggregation, aeolian and fluvial transport, and surface modification on Titan.
title Feeling the Pressure: Effects of Formation Pressure on the Physical Properties of Titan Haze Analogs
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2604.20057