This paper compares laboratory gas-phase spectra of neutral and cationic linear carbon-chain radicals with astronomical diuse interstellar band (DIB) spectra. The origin bands of the strong electronic transitions of the studied species, C (n\3È6), (n\2È4), (n\3, 4), do not coincide 2nH HC2nH` NC2n~2N` with detectable DIBs, except for HC (n\3), which possibly matches a weak feature. It is con- 2n~1N` cluded that the column densities of these species through the observed diuse clouds are below 2]1012 cm~2. The proÐle change and the shift of the maxima of the absorption bands with temperature are illustrated. The relation to radio-astronomical detection of carbon chains in diuse media is also discussed.