Far-IR spectra of PAHs (14–75 μm)

As a preparation to the IR satellite ISO we have decided to search for the spectral characteristics of PAHs at wavelengths longer than 14 μm. We have therefore measured the spectra of 44 PAHs in the 14–75 μm domain and found some features which seem common to several species. The main hands appear at 18.2, 21.3 and 23.0 μm and are found in respectively 46, 27 and 34% of the molecules.