Date/Time
Date(s) - 02/12/2003
2:00 pm - 3:00 pm

Title: Photochemistry in the Atmosphere of Titan: Formation of Titan Haze

Speaker: Dr. James Ferris

Institute: Rensselaer Polytechnic Institute
Department of Chemistry

Location: ABB 102

Description:

Titan, the largest moon of Saturn, has a dense atmosphere (1.5 bar)and an atmosphere consisting of about 98 % nitrogen and 1.5 % methane. The atmosphere has a dark haze layer that is believed to be due to the presence of organics formed by the action of energy on Titans atmosphere. The formation of haze is an on going model of the formation of complex structures from one of the simplest organic compounds, methane. Solar UV light is believed to be the principal energy source driving the conversion of methane to the haze layer in Titan^s atmosphere. Another energy source, electrons from the magnetosphere of Saturn, dissociates molecular nitrogen to nitrogen atoms that, in turn, react with methyl radicals to form HCN. Light in the 100-155 nm wavelength region converts methane to acetylene, ethylene and cyanoacetylene. Photolysis of acetylene, ethylene and cyanoacetylene generates a polymer, which is an analog of Titan^s haze. The optical properties of the haze analog have been measured and compared with those measured for a polymer prepared in discharge reactions and those calculated for Titan^s haze. The haze has been analyzed and the C/N ratio derived by the analysis was compared with that determined for haze analogs prepared by electric discharges. The rates and products of the photolysis are being measured. These results will facilitate the understanding of the data returned from the Huygens probe of the Cassini mission to Saturn when the probe passes through the atmosphere of Titan in January of 2005.