On the carriers of the celestial infrared vibrational bands and their excitation mechanisms

Abstract

The recent influx of high-quality infrared spectroscopic data has prompted an extensive reassessment of various laboratory models in comparison with the observed UIBs (Unidentified Infrared Bands). As a result, significant modifications were brought to the original paradigms. The focus here is on the correction of the coal model, characterized by: 1) a shift towards less aromatic materials of the same family (kerogens; the composition, structure and IR spectrum of these materials are extensively documented in the geology literature); 2) the introduction of a new excitation mechanism (chemiluminescence), based on the capture of hydrogen atoms by carbonaceous dust. The fundamental characters of this model, viz. chemical and structural disorder, and diversity of chemical bondings, naturally point to ways of further tailoring, in order to fit particular observations more closely.