Undergraduate Honors Theses

Thesis Defended

Spring 2011

Document Type

Thesis

First Advisor

false

Abstract

Titan, the moon of Saturn, has an atmosphere composed of methane (CH4), nitrogen (N2), and a thick, orange haze that obscures its surface. Titan haze aerosol analogs were generated by electric spark in a laboratory setting and the chemical and optical roperties of the analogs were studied through infrared spectroscopy and UV-Vis spectroscopy. Haze aerosol analogs were generated from initial gas mixture concentrations of 10% CH4 in N2, 2% CH4 in N2, and 0.4% CH4 in N2 for studying the chemical properties, while haze aerosol analogs were generated from initial gas mixture concentrations of 10% CH4 in N2 and 2% CH4 in N2 for studying the optical properties. The infrared spectroscopy data showed that overall chemical mass, specifically aliphatic hydrocarbon mass, increased with increasing initial CH4 gas concentrations, as did the polycyclic aromatic hydrocarbon concentration. These results directly support previous chemical composition data of aerosol analogs (Trainer et al., 2004). The UV-Vis data were used to calculate a relative imaginary refractive index k value, which revealed that haze aerosol analogs generated at lower initial CH4 concentrations absorbed more in the shorter wavelengths of the visible range, while haze aerosol analogs generated at higher initial CH4 concentrations absorbed more evenly over all visible wavelengths. This data did not closely support previous laboratory data regarding k values (Khare et al., 1984), which might be due to variations in pressure parameters of the experimental set-up. These results can be used to formulate a historical hypothesis of the chemical and optical properties of Titan’s haze aerosols and predict how the haze will behave chemically and optically in the future as atmospheric CH4 concentration decreases over time.

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