| Name: KARRI VENKATA LAKSHMI |
| Affiliation: GITAM Deemed to be University, Hyderabad |
| Conference ID: ASI2026_126 |
| Title: Theoretical spectroscopic study of aromatic and N-heterocycles: Potential carriers of interstellar AIBs and UV bump at 217.5 nm |
| Abstract Type: Poster |
| Abstract Category: Stars, Interstellar Medium, and Astrochemistry in Milky Way |
| Author(s) and Co-Author(s) with Affiliation: KARRI VENKATA LAKSHMI(Department of Physics, School of Science, GITAM (Deemed to be University), Hyderabad -502329 (TS), India.), Mahadevappa Naganathappa(Department of Physics, School of Science, GITAM (Deemed to be University), Hyderabad -502329 (TS), India.) |
| Abstract: Nitrogen-containing heterocyclic molecules embedded in aromatic frameworks are considered promising contributors to the chemical evolution of the interstellar medium. Polycyclic aromatic nitrogen heterocycles (PANHs) have been proposed as potential carriers of the aromatic infrared bands (AIBs), particularly the 6.2 µm feature, and contributors to the interstellar ultraviolet extinction bump at 217.5 nm.
In this work, we present a theoretical investigation of the microwave, infrared, and ultraviolet/visible spectroscopic properties of selected aromatic and nitrogen-heterocyclic molecules in the gas phase and aqueous environment. Density functional theory calculations are performed at the B3LYP/aug-cc-pVTZ level. For the first time, we report spectroscopic signatures of a tricyclic tetrahydroquinoline and fused polycyclic quinoline systems, including their carboxylic acid derivatives in neutral and ionic states.
Nitrogen incorporation enhances molecular dipole moments, leading to stronger rotational transitions and improved detectability compared to symmetric PAHs. Rotational spectra are simulated under astrophysical conditions, while vibrational and electronic absorption analyses reveal characteristic features relevant to AIBs and the 217.5 nm extinction band. These results support PANHs as viable molecular candidates in interstellar environments.
Keywords: Astrochemistry, Polycyclic aromatic hydrocarbons (PAHs), N-heterocycles, Rotational spectra, Infrared spectra, Electronic absorption spectra.
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