Physisorption of CO₂ on non-ice materials relevant to icy satellites

Journal Article · Tue May 01 00:00:00 EDT 2007 · Icarus

DOI:https://doi.org/10.1016/j.icarus.2007.04.012· OSTI ID:922891

Hibbitts, Charles A. ^[1]; Szanyi, Janos ^[2]

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1. Johns Hopkins Univ., Baltimore, MD (United States)
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

CO₂ is known to adsorb onto clay and other minerals when a significant atmospheric pressure is present. We have found that CO₂ can also adsorb onto some clays when the CO₂ partial pressure is effectively zero under ultra-high vacuum (UHV) if cooled to the surface temperatures of the icy satellites of Jupiter and Saturn. The strength of adsorption and the spectral characteristics of the adsorbed CO₂ infrared (IR) ν₃ absorption band near 4.25 μm depend on the composition and temperature of the adsorbent. CO₂ remains adsorbed onto the clay mineral montmorillonite for >10 s of min when exposed to a vacuum of ~1×10^-8 Torr at ~125 K. CO₂ does not adsorb onto serpentine, goethite, or palagonite under these conditions. A small amount may adsorb onto kaolinite. When heated above 150 K under vacuum, the CO₂ desorbs from the montmorillonite within a few minutes. The ν₃ absorption band of CO₂ adsorbed onto montmorillonite at 125 K is similar to that of the CO₂ detected on the saturnian and Galilean satellites and is markedly different from CO₂ adsorbed onto montmorillonite at room temperature. We infer the adsorption process is physisorption and postulate that this mechanism may explain the presence and spectral characteristics of the CO₂ detected in the surfaces of these outer satellites.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 922891
• Report Number(s): PNNL-SA-58793; 19807; KP1704020; TRN: US200803%%464
• Journal Information: Icarus, Vol. 191, Issue 1; ISSN 0019-1035
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CARBON DIOXIDE
ADSORPTION
MONTMORILLONITE
PARTIAL PRESSURE
SATELLITES
JUPITER PLANET
SATURN PLANET
Environmental Molecular Sciences Laboratory