Dynamical molecular regions in interstellar clouds

Work on three problems concerning the chemistry and dynamics of star forming regions is addressed. Most of the work was done in collaboration with David A. Williams. A chemical model of core D of TMC-1 is described; it is consistent with that dense core having evolved to its present physical state in the last 10(5) years. Slow-mode wave excitation by the nonlinear evolution of fast-mode waves is examined as a possible mechanism for the production of structures, including dense cores, in molecular sources. Sufficient atomic hydrogen may be present at the births of some dense cores that the radiative association of O with H is important in the initiation of the gas phase chemistry.