C. Moutou 1, K. Sellgren 2, L. Verstraete 3 A. Léger 3 D. Rouan 4, & M. Werner 5
1 Observatoire de Haute Provence
2
3 IAS, Orsay. France
4 Observatoire de Meudon, France
5 JPL
We have obtained high resolution spectra of the two brightest reflection
nebulae, i.e. NGC7023 and NGC2023, with the ISO instrument SWS. A careful
analysis of these spectra allows us to draw some conclusions on the IR
emission properties of the carriers and on their excitation
mechanism. From the observation of pure rotational H2 lines we extract
the gas properties and physical conditions of the environments.
Asymmetries in the broad band profiles, variations of band ratios from one
object to the other, energy distribution in the bands and in the continuum
are investigated and lead to interesting conclusions in terms of
characteristics of aromatic species.
Low frequency modes of aromatic species are detected for the first time, at
15.8 and 16.4 
and compared to recent laboratory data.
We report on a search for the signature of the
fullerene cation
at
7.11 and 7.51 ,
and give a new estimate of the upper limit on its
abundance.