Surface formation routes of interstellar molecules : a laboratory study

It has been a long standing problem in astrochemistry to explain how molecules can form in a highly dilute environment as the interstellar medium. In recent years it has become clear that solid state reactions on icy grains play an important role in the formation of both simple and rather complex molecules. Laboratory based experiments that simulate the UV processing or the impact of H-atoms on interstellar ice analogues are needed in order to investigate the underlying processes. This is the topic of this PhD thesis that mainly summarizes research on SURFRESIDE, one of the ultra-high vacuum setup in the Sackler Laboratory for Astrophysics. It is shown how under fully controlled conditions molecules form when CO and O2 containing ices are bombarded by hydrogen atoms. Surface reaction schemes for methanol, water, carbon dioxide and formic acid formation at low temperatures in space are presented, and it is discussed how species may be chemically linked in space