On the Relation between C2 and CH/CH+ Molecules, Molecular/Atomic Hydrogen and Major 5780/5797 DIBs

Relations between abundances of the interstellar C2 molecule and other diatomic species as CH and H2 are presented based on 33 available sight-lines. Spacial correlations between column densities of diatomic molecules suggest that the C2 molecule is closely related to interstellar CH with correlation coefficient equal to 0.87±0.05. The column density ratio in the case of C2 and CH molecules in the ISM is equal to 1.13±0.12.