The quantum yield of O(^1S) in CO_2 photolysis retrieved from the Martian atmosphere. The quantum yield of O(^1S) in CO2 photolysis

• Published in: Astronomy and astrophysics (Berlin)
• Main Authors: Gkouvelis, Leonardos, Akin, Can, Heng, Kevin
• Format: Journal Article
• Language: English
• Published: 11.09.2024
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/202450588

Photochemistry studies the interactions between light and molecules. Ultraviolet radiation interacts with the atmosphere, and due to its energy, it can dissociate, excite, or ionize its constituents, which initiate other processes. A good knowledge of the interaction between photons of different energies with molecules and atoms is crucial for accurately modeling the atmospheric physics and for climate predictions. Despite its importance, photo-fragment dynamics lacks data because the experimental setup is difficult. We used the upper Martian atmosphere as a natural laboratory to measure the quantum yield $ O(^1S) $ from $ CO_2+h nu $ as a function of wavelength. We analyzed four years of continuous remote-sensing observations from the NASA MAVEN/IUVS spectrograph within a Bayesian framework analysis tool. We retrieved the quantum yield for the first time through its entire production spectral range, approx 80-126 nm, and achieved uncertainty from 10 to 20<!PCT!> on average. While at Lyman-$ alpha $ (121.6 nm), we achieved a precision of 2<!PCT!> by taking advantage of the properties of the upper Martian atmosphere.