Alkali and Halogen Chemistry in Volcanic Gases on Io

Abstract

We use chemical equilibrium calculations to model the speciation of alkalis and halogens in volcanic gases emitted on Io. The calculations cover wide temperature (500-2000 K) and pressure (10^-6 to 10^+1 bars) ranges, which overlap the nominal conditions at Pele (T = 1760 K, P = 0.01 bars). About 230 compounds of 11 elements (O, S, Li, Na, K, Rb, Cs, F, Cl, Br, I) are considered. We predict the major alkali and halogen species in a Pele-like volcanic gas and the major alklai and halogen condensates. We also model disequilibrium chemistry of the alkalis and halogens in the volcanic plume. Based on this work and our prior modeling for Na, K, and Cl in a volcanic plume, we predict the major loss processes for the alkali halide gases are photolysis and/or condensation onto grains. On the basis of elemental abundances and photochemical lifetimes, we recommend searching for gaseous KCl, NaF, LiF, LiCl, RbF, RbCl, CsF, and CsCl around volcanic vents during eruptions. Based on abundance considerations and observations of brown dwarfs, we also recommend a search of Io's extended atmosphere and the Io plasma torus for neutral and ionized Li, Cs, Rb, and F.

arXiv comment32 pages, 4 tables, 5 figures; accepted for publication by Icarus

References in corpus (4)

• The Spectra of T Dwarfs. II. Red Optical Data
• LSR0602+3910 - Discovery of a Bright Nearby L-type Brown Dwarf
• The Far Ultraviolet Spectrum of the Io Plasma Torus
• Detection of Atomic Chlorine in Io's Atmosphere with HST/GHRS

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• On the ultraviolet anomalies of the WASP-12 and HD 189733 systems: Trojan satellites as a plasma source
• Silicon Tetrafluoride on Io
• Spectroscopic mapping of Io's surface with HST/STIS: SO${}_2$ frost, sulfur allotropes, and large-scale compositional patterns
• The collisional atomic processes of Rydberg alkali atoms in Geo-cosmical plasmas