Chérif F. Matta¹ ² ³
Dept. of Chemistry & Physics, Mount Saint Vincent University, Halifax, NS, Canada B3M 2J6.
Corresponding author: cherif.matta@msvu.ca
The enigma of Diffuse Interstellar Bands (DIBs) — absorption features in stellar spectra due to dust and molecular clouds between stars and the observer on Earth — has puzzled astronomers for over a century. Recent work has shed light on this mystery by exploring potential molecular carriers for DIBs and mapping their relationship to interstellar environments. We have discovered four new families of strongly correlated DIBs through a statistical analysis of the Apache Point Observatory (APO) DIB catalog. Ionized molecular candidates associated with the first observed DIBs at 5780 and 5797 Å, using both observational and computational chemistry techniques (e.g., TD-DFT), are proposed. Key candidates, such as glycolamide, lactamide, and oxamic acid for the 5780 Å DIB family, along with 2-cyclopenten-1-one and 3(2H)-selenophenone for the 5797 Å family, emerged through correlations in spectral line strengths and functional group analysis. Notably, recent observational data from the molecular interstellar cloud (code: G+0.693-0027) detected glycolamide, which re-enforces our theoretical predictions and supports the role of this molecule as a potential DIB carrier. The spectral signatures of ions, as opposed to neutral species, match observed DIB features in the visible range, underscoring the importance of ionization in identifying DIB carriers. For instance, anions of 3(2H)-selenophenone display bands near 579.4 nm, closely corresponding to the prominent 5797 Å DIB. It is further suggested that molecular candidates connected to DIBs often possess amide and hydroxyl groups, indicating potential structural motifs of interstellar molecules. The work underscores the need for comprehensive databases of ionized molecular spectra, which can be used to refine DIB associations and guide future laboratory and observational studies.
Please find the link to Cherif's youtube interviews with scientists here!
The 2025 edition of the Virtual Winter School on Computational Chemistry is proudly sponsored by the School of Chemistry at the University of Edinburgh.
The Cooper Union for the Advancement of Science and Art is pleased to provide support for the 2024 VWSCC through a generous donation from Alan Fortier.
We thank Leibniz Institute for Catalysis (LIKAT) and CECAM for their support.
Virtual Winter School on Computational Chemistry
Diffuse interstellar bands (DIB)as described by Prof Cherif occured as a result of interaction of dust and molecular clouds between stars and observers on earth.
Being a major problem to the astronomers, efforts have been made through exploring potential molecular Carrier in mapping their relationship to interstellar environment. And through statistical analysis, four families have been discovered that are strongly correlated DIB Catalogue.