CHAPTER 7: Catalytic Chemistry in Space? Reactions on Bare Dust Grains Check Access

The gas phase chemistry described in Chapter 6 depends on the presence of abundant molecular hydrogen. However, in interstellar clouds of the Milky Way galaxy there are no efficient ways of making molecular hydrogen in gas phase reactions. Can it be that molecular hydrogen is made efficiently in reactions on the surfaces of dust grains? Many detailed experiments and theoretical investigations support the view that dust grains can catalyze the formation of molecular hydrogen. Therefore, all of the interstellar chemistry described in Chapter 6 depends essentially on the presence of dust grains, firstly, to produce the molecular hydrogen required in the chemistry and, secondly, to shield the molecules from the destructive effects of ultraviolet starlight.