Gas-Phase Reactions in the ISM: Rate Coefficients, Temperature Dependences, and Reaction Products

Information about the rate coefficients and products of processes that occur in the interstellar medium are required as input to computer models that seek to reproduce the abundances of the rich variety of molecules that have been observed in different regions of the interstellar medium. In this brief review, I seek to identify the different kinds of gas-phase processes for which information is required and to consider the experimental, theoretical, and semi-empirical methods which are employed to measure or predict rate coefficients, k(T), and how they depend on temperature (T) - and also how the products of reactions can, in favourable cases, be observed.