[astro-ph.EP] Photochemical hazes play an important role in shaping the spectra and radiative balance of N2-dominated planetary atmospheres.
We present newly acquired FTIR and retrieved optical constants (N=n+ik) of laboratory-generated haze analogs from N2/CH4 and N2/CH4/CO gas mixtures under plasma discharge conditions.
The retrievals use particle densities newly measured for the CH4-series and previously published particle densities for the CO-series. The experiments systematically explored CH4 concentrations from 0.5% to 10% and CO concentrations from 0% to 5% with fixed 5% CH4. Using measured particle densities together with the Beer-Lambert law and subtractive Kramers-Kronig (SKK) relation, we derived optical constants over the 350-25000 cm-1 (0.4-28.6 μm) spectral range, with the 0.4-25 μm results presented in the main text.
The infrared spectra reveal prominent absorption features associated with hydrocarbon-, nitrogen-, and oxygen-bearing functional groups. Increasing CH4 abundance enhances aliphatic hydrocarbon features and corresponds to decreasing particle density, whereas increasing CO abundance promotes oxygen incorporation, broader mid-infrared absorptions, and higher particle density.
The derived k spectra exhibit strong absorptions near ~3 μm, ~4.6 μm, and ~6-10 μm, while the real refractive index n generally ranges from ~1.2 to 1.7. The controlled CH4– and CO-series establish composition-dependent variations in haze optical properties.
A benchmark comparison among Titan-, Pluto-, and Triton-like haze analogs then uses these experimentally identified trends to interpret the optical differences among N2-dominated planetary haze compositions. The density and optical constants provide laboratory constraints for atmospheric radiative transfer models and for interpreting planetary and exoplanetary spectra from spacecraft and telescopes.
Zhengbo Yang, Chao He, Haixin Li, Sai Wang, Xiao’ou Luo, Yu Liu, Sarah M. Hörst
Comments: 20 pages, 6 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2609.22982 [astro-ph.EP] (or arXiv:2609.22982v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2609.22982
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From: Zhengbo Yang
[v1] Sat, 19 Sep 2026 12:28:53 UTC (1,617 KB)
https://arxiv.org/abs/2609.22982
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