SIMBAD references

We present new laboratory data to interpret the Infrared Space Observatory (ISO) spectra of protostellar objects, and particularly RAFGL 7009S. Our experimental results show that solid methanol and carbon dioxide exhibit specific intermolecular interactions. We propose the formation of a Lewis acid-base complex between carbon dioxide and methanol molecules to explain specific substructure of the 15.2 µm CO₂ bending mode observed in different objects. The various CO₂ bending mode patterns observed in many lines of sight can be interpreted as a combination of both this complex formation and the temperature evolution of the ices. The temperature induced segregation of ice mantles containing CO₂ can be monitored by the ¹³CO₂ stretching mode shift toward the pure CO₂ ice position. The large width observed for this mode towards interstellar sources partly results from the different temperatures sampled along the line of sight. Given the amount of methanol involved in RAFGL 7009S, on the basis of ground based observations, we derive that about half of the so called ``6.85µm'' band and a quarter of the 4.9µm bands can be accounted for by the deformation modes and 2ν₈ transitions of CH₃OH.