On bare carbon chain anions as possible carriers of the diffuse interstellar features

The recent hypothesis that some of the diffuse interstellar bands originate in bare carbon chains such as C-6(-), C-7(-), C-8(-) and C-9(-) is tested using echelle spectra covering the whole range of possible (i.e. found in t he laboratory) transitions of these molecules. Most of the expected feature s are below the level of detection in astrophysical spectra, and even those observed show intensity ratios that are different from those in the labora tory. Thus the hypothesis is very unlikely to be true.