Ultraviolet photochemistry of cyanoacetylene: Application to Titan

Cyanoacetylene is believed to have had a central role in the formation of the pyrimidines essential for RNA synthesis leading to the origin of life on Earth. Cyanoacetylene has also been detected on Titan, Saturn's largest moon, and the only moon in the solar system that possesses a dense atmosphere. It is generally accepted that photochemistry plays a major role in the formation of the complex organic molecules and aerosols found in Titan's atmosphere. Because of its long wavelength absorption and low dissociation threshold it is expected that cyanoacetylene is an important part of these photochemical processes. Since cyanoacetylene would also have been subject to ultraviolet light in the atmosphere of early Earth, an investigation of cyanoacetylene photochemistry on Titan might lead to a better understanding of both the photochemical reactions occurring on primitive earth and the processes of chemical evolution as they occur in planetary atmospheres. The effects of irradiation wavelength, mixing with Titan's atmospheric gases, reducing the temperature and lowering cyanoacetylene partial pressures on product formation and polymer composition have been determined with the ultimate goal of understanding the chemical transformations taking place in Titan's atmosphere.