Published online by Cambridge University Press: 14 August 2015
Absorption line spectroscopy in the ultraviolet, visible, and infrared regions can provide important probes of interstellar chemistry. Significant recent developments include the application of optical absorption line techniques to the study of thick molecular clouds and the improvements in infrared detectors that will eventually lead to effective interstellar spectroscopy in the infrared. Demands for basic molecular data will grow in scope and in level of precision.