C2 and Diffuse Interstellar Bands

C 2 , the simplest multicarbon molecule is a useful astronomical tool, because the analysis of its lines allows to determine the physical conditions in interstellar clouds. C 2 abundances give information about the chemistry of interstellar clouds, especially on the pathway to the formation of long-chain carbon molecules, which may be connected with carriers of diffuse interstellar bands (Douglas 1977, Thorburn et al . 2003). Here we summarize all relations between C 2 and diffuse interstellar bands (DIBs).