On the Relation between Diffuse Bands and Other Interstellar Features

We discuss possible relations between different constituents of interstellar clouds, such as gas atoms (Fe i), simple molecular species (CH, CN), and the carriers of the puzzling diffuse interstellar bands (DIBs 5780, 5797, 5850 A) as well as dust grains. We exemplify that abundances of carriers of these spectral features, revealed by the Doppler components, may be astonishingly poorly related to each other. Spectra of interstellar clouds seem to be sensitive to the changes of the environmental parameters such as density, temperature, and irradiation from nearby stars. The diffuse bands' carriers likely do not occupy the same volumes with CH, CN, or Fe i and/or are much less sensitive to the processes related to the formation/destruction of these species.