Polycyclic aromatic hydrocarbons and the diffuse interstellar bands: a survey.

We discuss the proposal relating the origin of some of the diffuse interstellar bands (DIBs) to neutral and ionized polycyclic aromatic hydrocarbons (PAHs) present in interstellar clouds. Laboratory spectra of several PAHs, isolated at low temperature in inert gas matrices, are compared with the spectra of five reddened early-type stars selected from an extensive set of astronomical spectra. From this comparison, it is concluded that PAH ions are good candidates to explain some of the DIBS.