What Do We Know and What Do We Need to Know?

Abstract

I review recent progress in determining the rate coefficients appropriate to modelling interstellar chemistry, give some information on appropriate databases from which rate coefficients can be obtained, and point to the importance of the gas-grain interaction in determining molecular abundances. Although many of the fundamental gas-phase reactions have been studied in the laboratory, the failure of the models to explain the observations of water and methanol in cold clouds indicates that grains may have an important role, both in acting as a surface for freeze-out and in the synthesis of complex molecules. The major challenge in astrochemistry is to develop a more quantitative model for the role of grains and, in some cases, to incorporate a better, probably more complex, physical model for interstellar clouds.