Optical Constants of a Titan Haze Analog from 0.4 to 3.5 μm Determined Using Vacuum Spectroscopy

Titan's thick atmosphere is primarily composed of nitrogen and methane. Complex chemistry happening in Titan's atmosphere produces optically thick organic hazes. These hazes play significant roles in Titan's atmosphere and on its surface, and their optical properties are crucial for understanding many processes happening on Titan. Due to the lack of such information, the optical constants of laboratory-prepared Titan haze analogs are essential inputs for atmospheric modeling and data analysis of remote-sensing observations of Titan. Here we perform laboratory simulations in a Titan-relevant environment, analyze the resulting Titan haze analogs using vacuum Fourier transform infrared spectroscopy, and calculate the optical constants from the measured transmittance and reflectance spectra. We provide a reliable set of optical constants of Titan haze analogs in the wavelength range from 0.4 to 3.5 μ m and will extend it to 28.5 μ m in the near future, which can be used for analyzing both existing and future observational data of Titan. This study establishes a feasible method to determine optical constants of haze analogs of (exo)planetary bodies.