Oxirane: An Exotic Oxygenated Organic Compound on Titan?

After the discovery of CO, CO2, and more recently H2O in Titanʹs atmosphere, the chemistry of oxygenated organic compounds in this environment has been limited to theoretical studies only. Both kinetic and thermochemical models predict the formation of methanol and formaldehyde as the main O-organic products. Here we show that oxirane (also named ethylene oxide) is the main product in experiments designed to simulate the upper atmosphere of Titan; methanol and formaldehyde are not produced in detectable amounts. Oxirane has been previously detected in the interstellar medium and hot molecular cloud cores. The first opportunity to detect it in Titan will occur in 2005 January during the entry of the Huygens probe into the satelliteʹs atmosphere. Therefore, oxirane becomes a molecule of wide astrophysical interest.