Spectroscopic diagnostics of organic chemistry in the protostellar environment

A combination of astronomical observations, laboratory studies, and theoret ical modelling is necessary to determine the organic chemistry of dense mol ecular clouds. We present spectroscopic evidence for the composition and ev olution of organic molecules in protostellar environments. The principal re action pathways to complex molecule formation by catalysis on dust grains a nd by reactions in the interstellar gas are described. Protostellar cores, where warming of dust has induced evaporation of icy grain mantles, are exc ellent sites in which to study the interaction between gas phase and grain- surface chemistries. We investigate the link between organics that are obse rved as direct products of grain surface reactions and those which are form ed by secondary gas phase reactions of evaporated surface products. Theory predicts observable correlations between specific interstellar molecules, a nd also which new organics are viable for detection. We discuss recent infr ared observations obtained with the Infrared Space Observatory, laboratory studies of organic molecules, theories of molecule formation, and summarise recent radioastronomical searches for various complex molecules such as et hers, azaheterocyclic compounds, and amino acids. (C) 2001 Elsevier Science B.V. All rights reserved.