Level of Education of Students Involved

Undergraduate

Faculty Sponsor

Haiying He

College

Arts and Sciences

Discipline(s)

Physics, Astrochemistry

Presentation Type

Poster Presentation

Symposium Date

Spring 4-25-2024

Abstract

There are several peaks in the infrared (IR) spectrum of planetary nebulae (PNe) like NGC 7027 whose origins are unknown. This has been a long-standing puzzle in the study of PNe. This project explores heteroatom substitution in polycyclic aromatic hydrocarbons (PAHs) as a possible origin for these unidentified infrared emission (UIE) peaks. The heteroatom elements explored in this study are nitrogen, oxygen, phosphorus, silicon, and sulfur. Previous work has demonstrated that 3- and 4- ring PAHs emit a spectrum close to current spectrum data for UIE and a previous group tested nitrogen substitution in similar structures with varied results. I used the Gaussian 09 program to model these PAHs substituting carbon with these heteroatom elements and a Python program adapted from GaussSum to analyze the resulting spectra of these molecules. I, first, analyzed the stability of the substituted PAHs by calculating their formation energy. Phosphorus had the lowest formation energy of all the heteroatoms with an energy of -0.1968 eV for the most stable substitution. Overall, I found that the heteroatom substituted PAHs were fairly stable and could possibly be found within the circumstellar environment of PNe. Calculated IR spectra will be compared with IR spectra from planetary nebulae.

Biographical Information about Author(s)

Emily Pavasars is a senior Physics major at Valparaiso University with minors in Education and Mathematics. This presentation is the culmination of her four years of study here at Valparaiso University. She will be attending a graduate program in the fall, pursuing her Physics PhD.

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