New Observations of Infrared Astronomical Bands: IRAS-LRS and 3μm Ground-Based Spectra

We present infrared spectral data of a sample of fourteen IRAS sources. The observations include the IRAS Low Resolution Spectra, and ground- based 3μm spectroscopy. The sources have been selected because they have strong emission features at 7.7, 8.6 and 11.3μn in their IRAS-LRS spectra. We have detected in most of them the well-known features at 3.3 and 3.4μm, together, with a plateau at 3.4–3.6μm. Additionally, in two sources observed at higher resolution, new emission features at 3.46, 3.51 and 3.56μm are detected. Together with the 3.40μm feature they arise on top of a broad plateau which clearly emerges above the 3μm continuum. Wings are present on the edges of the 3.3μm feature. The IRAS spectra also reveal an emission plateau above the continuum longward of 11.5μm. Possible interpretations for the new features are suggested and a preliminary analysis of these data is presented in the context of the Polycyclic Aromatic Hydrocarbons hypothesis.