Formation of complex chemical species in astrochemistry (a review)

In recent years, a rapid growth in a new area of space studies??astrochemistry??has been observed. Its subject is the chemical evolution and chemical diversity of interstellar matter. Molecules yield unique information concerning physical conditions in the interstellar medium and, in particular, in the star-formation regions, through spectral observations of the matter in the gas-phase and dust fractions via rotational and vibrational transitions of interstellar molecules. Moreover, an understanding of the chemistry of molecules can tell us about the lifetime and history of the observed objects. Such an understanding, however, requires detailed chemical knowledge of the gas-phase reactions and grain-surface chemical processes that very often take place under rather exotic conditions strongly differing from those for chemical reactions in the laboratory. Note that the interests of chemists and astronomers in this new area are different: chemists are more likely to be interested in chemical diversity throughout the Universe, whereas astronomers are more likely to use molecules as probes of physical processes.