Chapter 7: Surface Chemistry on Interstellar Dust Grains

The presence of dust in the interstellar medium was discovered because of the obscuration it causes of the light of distant stars. That obscuration also shields the interiors of interstellar clouds from the destructive effects of starlight and encourages chemistry to develop there. However, dust contributes to interstellar chemistry in other ways, too. In this chapter, we describe the role of dust in enabling surface chemistry to take place in interstellar clouds. This surface chemistry is of greatest importance in the case of molecular hydrogen formation, because H₂ plays a seminal role in almost all of interstellar chemistry (as seen in Chapters 4 and 5, particularly). Theoretical and experimental evidence supporting the production of H₂ and some other species in surface chemistry is described in this chapter.