Student: Allison Wold, Undergraduate Student in Chemistry, University of Northern Iowa
Research Mentor: Joshua Sebree
Stable Isotope Chemistry in Titan Haze Aerosol
Titan, a moon of Saturn, has a thick atmosphere made up of N2 and a few percent CH4, with a surface pressure of 1.5x that of Earth. Titan’s atmosphere is believed to be that similar to that of early Earth before the rise of molecular oxygen. Even though the atmospheric conditions of Earth at the time of the origin of life are not known, it has been shown in previous experimental studies that prebiotic molecules such as amino acids and nucleobases can be formed via atmospheric synthesis. Studying Titan’s atmosphere can give new insights into prebiotic chemistry and habitability. One significant source of information on the history and evolution of the atmosphere is the measurement of stable isotopes that comprise each chemical species, specifically 12C/13C, 14N/15N and D/H in major gases such as N2, CH4, and higher order hydrocarbons. The fractionation associated with the formation of Titan aerosol analogs are explored in the laboratory as a function of environmental parameters. Gas mixtures are flowed into a reaction chamber, where they undergo UV-irradiation via a deuterium lamp. The resulting aerosol samples are collected and analyzed using isotope-ratio mass spectrometry (IRMS). This project focuses on pyridine (C5H5N) and nitrogen gas mixtures, with and without CH4, as a function of pressure. We compare the results of the organic isotopes for these aerosol products to their starting molecules, in order to provide a more complete picture of how stable isotopes may be processed and distributed in Titan’s atmosphere.