Astrobiology Seminar / Fall 2007

November 20

Prof. Mats Larsson

Stockholm University

Biomolecular Precursors in Space?

The possibile extraterrestrial origin of biomolecules has been discussed since the discovery of amino acids in meteorites. Whereas biomolecules in the early solar system probably would have been destroyed by the strong UV field present, this is not necessarily the case for precursor molecules such as alcohols, aldehydes, ethers and nitriles. Thus, one cannot rule out that interstellar molecules played an important role in the formation of biomolecules on earth. Three formation mechanisms are usually considered in interstellar chemistry: i) grain surface processes; ii) radical-neutral processes; and iii) ion-molecule reactions followed by dissociative recombination. I will discuss the formation of interstellar oxygen and nitrogen containing molecules by mechanism iii). In doing so, I will also discuss the formation and destruction of H3+, the key actor in interstellar chemistry. Its destruction by electrons has been controversial for many years, but recently there has been much progress both experimentally and theoretically in the understanding of electron-H3+ recombination.