General Physics Physics Seminar 29 November 2007


Plasma and surface science in molecular astrophysics

Harold Linnartz

Laboratory Astrophysics Head Sackler Laboratory for Astrophysics
Leiden Observatory
Postbus 9513, NL 2300 RA Leiden


More than 140 different molecules have been identified in star-forming regions. These range from simple diatomic species such as CO to exotic radicals (linear HCCCCCCCCCCN) and complex organic molecules like CH3OCH3 and CH3CH2CN. This chemical complexity has been explained for many years by gas-phase processes driven by cosmic-ray induced ionization but new models show that such processes only reproduce observed abundances of the smaller and open shell, i.e. unstable species. Exciting new evidence has now been found that icy dust grains with temperatures as low as 15K act as catalytic sites for molecule formation and that the formation of the more complex species involves surface processes in ices on interstellar grains. Thermal and UV processing of the ices in combination with a permanent bombardment by H-atoms subsequently triggers a so far barely understood chemical evolution. This talk will give a laboratory view on the physical and chemical processes that are involved in star (and ultimately planet) formation. It shows that plasma and surface processes go hand-in-hand.