OVERVIEW OF NITRILE COMPOUNDS IN TITAN'S ATMOSPHERE: HCN (HYDROGEN CYANIDE), HC3N (CYANOACETYLENE), AND HC5N (CYANOBUTADIYNE)

• Main Author: Febrianti, Sindy
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/68751
• Institution: Institut Teknologi Bandung

Titan is known as the only natural satellite in the Solar System that has an atmosphere with main composition 94,2% nitrogen (N2), 5,6% methane (CH4) and 0,2% hydrogen (H2). Titan’s atmosphere is the site of complex chemical reactions with solar flux of radiation as the main energy sources. One of the compounds that readily formed in Titan’s Atmosphere are nitrile compounds, that is, chemical compounds that involve hydrogen, carbon, and nitrogen atoms in the formations (H – C – N). The most abundant nitrile compound in Titan’s atmosphere is HCN (Hydrogen Cyanide). This final project focuses on studying the photochemical processes that lead to the formation nitrile compounds in Titan’s atmosphere through literature studies, as well as obtaining spectra of HCN, HC3N, and tentatively HC5N in Titan’s atmosphere by selecting and analysing ALMA data. Subsequently, the ratio of abundance values of HC3N and HC5N against HCN in various layers of Titan’s atmosphere are obtained to infer their relative formation. Moreover, CASA (Common Astronomy Software Applications) is used to obtain Titan’s spectra from the ALMA data. To obtain the value of the abundance ratio of HC3N and HC5N with respect to HCN is performed by using radiative transfer calculations with the PSG (Planetary Spectrum Generator) model from NASA. After selecting ALMA data, the HCN spectra have been obtained in the 88 -– 89 GHz frequency range (for HCN(1-0)) and 264 — 266.5 GHz (for HCN(3- 2)) and HC3N in the 216 — 219 GHz frequency range (for HC3N(24-23)), 227 -– 229 GHz (for H3N(25-24)), and 243.5 -– 246 GHz (for HC3N(27-26)). The spectrum of HC5N has not been conclusively detected. The spectra obtained were then analyzed, and it was found that the photochemical reaction process for the formation of nitrile compounds occurs mostly in the mesosphere layer of Titan with an altitude range of 500 – 700 km. Titan’s photochemical reactions produce different abundances of compounds depending on altitudes, which is also caused by different energy sources of these photochemical reactions.