Fluorinated Gases as Technosignatures | Sara Seager | IAUS404

Fully Fluorinated Non-Carbon Compounds as Exemplary Technosignature Gases Presented by Sara Seager Massachusetts Institute of Technology Presented at IAU Symposium 404: Advancing the Search for Technosignatures | 2–6 March 2026 ABSTRACT: Waste gases from advanced civilizations might be detectable in the future in atmospheres of exoplanets. We highlight nitrogen trifluoride (NF3) and sulfur hexafluoride (SF6) as prime candidates for technosignature gases. These gases are not produced or used by Earth's life, which does not create molecules containing N-F or S-F bonds or fully fluorinated molecules of any kind. The unique industrial uses of NF3 and SF6, which are not dependent on specific species unlike biosignature gases, make them potentially universal technosignatures. Key attributes of NF3 and SF6 include their very low solubility in water, distinct spectral features, and long lifetimes in a planetary atmosphere. NF3, with no natural sources, was not found in Earth’s atmosphere before industrial times. SF6 is emitted in only small amounts from volcanic eruptions. To discern SF6's non-biological origin, we propose observing SiF4, which volcanoes emit in significantly greater amounts than SF6. Other fully fluorinated non-carbon human-made molecules lack detailed information on their chemical and spectral properties. We further explore why Earth life avoids fluorine and note the challenge in clearly differentiating an extraterrestrial life's byproduct from a technosignature gas. KEYWORDS: technosignature gases, nitrogen trifluoride, NF3, sulfur hexafluoride, SF6, exoplanet atmospheres, atmospheric spectroscopy, biosignatures vs technosignatures, industrial pollutants, MIT Presented 2–6 March during Advancing the Search for Technosignatures, an online symposium from the International Astronomical Union (IAU; https://www.iau.org/) and Blue Marble Space Institute of Science (BMSIS; https://bmsis.org/).