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Astron. Astrophys. 357, 793-800 (2000)

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Carbonic acid production in H2O:CO2 ices

UV photolysis vs. proton bombardment

P.A. Gerakines 1, M.H. Moore 1 and R.L. Hudson 2

1 Code 691, Astrochemistry Branch, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
2 Department of Chemistry, Eckerd College, St. Petersburg, FL 33733, USA

Received 7 October 1999 / Accepted 6 March 2000


We have the unique ability to perform ultraviolet photolysis ([FORMULA] eV [FORMULA]) and ion irradiation (0.8 MeV [FORMULA]) in the same experimental set-up, with ices created under identical conditions. We present experiments that show the formation of carbonic acid ([FORMULA]) from [FORMULA]:[FORMULA] ice mixtures exposed to either UV photons or high-energy protons. CO and CO3 were also formed in these experiments. Results show that while [FORMULA] is readily formed by [FORMULA] bombardment, its formation by UV photolysis is limited by the penetration of UV photons into the ice. [FORMULA] production pathways are investigated. Intrinsic IR band strengths are determined for eight IR features of [FORMULA]. Implications for ices found in various astrophysical environments are discussed.

Key words: molecular data – molecular processes – methods: laboratory – comets: general – planets and satellites: general – ISM: molecules

Send offprint requests to: P.A. Gerakines (Perry.A.Gerakines@gsfc.nasa.gov)

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© European Southern Observatory (ESO) 2000

Online publication: June 5, 2000