Theoretical quantum chemical study of protonated - deuteronated PAHs: Interstellar implications

Abstract

Diffuse Interstellar Bands (DIBs) are optical absorption features on the interstellar extinction curve. Ultra-high resolution spectroscopic observations suggest that at least some of these features are due to large molecules. Observational results also reveal that the strengths of the DIBs are not strongly correlated with each other, implying that there must be several carriers. Considering the wide range of interstellar species and the cost and duration of experimental work that is involved to determine the carriers of DIBs, Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TDDFT) calculations offer opportunities to investigate which molecules are suitable for laboratory studies. The widespread presence of Polycyclic Aromatic Hydrocarbons (PAHs) in astrophysical environments is known from observations of the Unidentified Infrared (UIR) emission bands. Since PAHs are stable enough to be present under interstellar conditions, they are good candidates to be the carriers of the DI...