The profiles of the 3 to 12 µm PAH features1

We present spectra of the 3.3 µm and 11.2 µm PAH features of a large number of stellar sources, planetary nebulae, reflection nebulae, H II regions and galaxies, obtained with ISO-SWS. Clear variations are present in the profiles of these features. Most of the sources show a symmetric 3.3 µm feature peaking at �3.290 µm, while only very few show an asymmetric 3.3 µm feature peaking at a slightly longer wavelength. The profiles of the 11.2 µm feature are distinctly asymmetric. The majority of the sources has a 11.2 µm feature peaking between 11.20 and 11.24 µm, with a very steep blue rise and a low tail-to-top ratio. A few sources show a 11.2 µm feature with a peak position of �11.25 µm, a less steep blue rise and a high tail-to-top ratio. The sources are classified independently based on the 3.3 and 11.2 µm feature profiles and peak positions. Correlations between these classes and those based on the 6-9 µm features (Peeters et al. 2002a) are found. In particular, sources with the most common profiles in the 6-9 µm region also show the most common 3.3 and 11.2 µm feature profiles. However, the uncommon profiles do not correlate with each other. Also, these classifications depend on the type of object. In general, H II regions, non-isolated Herbig AeBe stars and YSO's show the same profiles for all 3-12 µm features. Many planetary nebulae and Post-AGB stars show uncommon feature profiles. The 3 galaxies in our sample show the same profiles as the H II regions for all but the 11.2 µm feature, being similar to that of evolved stars. The observed pronounced contrast 1 Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA.