D2 ← D0 transition of the anthracene cation observed by cavity ring-down absorption spectroscopy in a supersonic jet

In an attempt to contribute to the explanation of the diffuse interstellar bands (DIBs), we have studied the absorption spectrum of the anthracene cation (An+) in a supersonic jet by cavity ring-down spectroscopy. The D2 ← D0 transition of An+ has been located at 708.76 ± 0.13 nm. This means that the same transition observed in an argon matrix is redshifted by 13.65 nm. Although the band position determined in the laboratory coincides with the position of a weak feature in the DIB spectrum, the measured width is too broad to comply with the astronomical observation.