Abstract
Attention is given to the variety of diatomic molecules that emerge in diffuse clouds of the interstellar medium through the combination of molecular H with C, which can be studied by modern detectors and spectrographs to yield molecular absorption lines that are seen against background early-type stars and result in accurate column densities. The results presently obtained by these methods imply that CN is a third-generation module produced by a neutral-neutral C2 + N reaction. Similarly, CH(+) is associated with warm H2 and is probably produced by shock fronts. A gas network is proposed for the production of these molecules.
