HR: 0800h
AN: P11D-0807    [Abstracts]
TI: The perturbation of near IR optical features of water ice induced by frozen acids, brines and organic polymers.
AU: Orlando, T M
EM: thomas.orlando@chemistry.gatech.edu
AF: School of Chemistry and Biochemistry, Georgia Institute of Technology, 91 Atlantic Dr., Atlanta, GA 30332, United States
AU: * Grieves, G A
EM: gregory.grieves@chemistry.gatech.edu
AF: School of Chemistry and Biochemistry, Georgia Institute of Technology, 91 Atlantic Dr., Atlanta, GA 30332, United States
AU: McCord, T
AF: Space Sciences Institute, NW, PO Box 667, Winthrop, WA 98862, United States
AB: We report the temperature and pH dependencies of the near IR optical signatures of low-temperature ice containing acids, brines or tholins. In the case of flash frozen acids and brines, the 1.5 and 2 micron features shift in wavelength and broaden primarily due to the presence of solvated protons. The role of protons can be seen most dramatically when examining the dissolution of sulfuric acid in ice. Specifically, at temperatures below 135 K, the second pK_a of sulfuric acid increases as the temperature decreases due to the increased coupling of the SO₄^2- with the surrounding water molecules. These shifts and broadening are also inherent in the dissolution of MgSO₄ or Na₂SO₄, two candidate materials possibly present in the non-ice regions of Europa. We also compare the optical signatures of organic polymers (tholins) created by discharge devices vs. those created photochemically. The relevance of this work to Titan's surface composition is discussed.
DE: 5410 Composition (1060, 3672)
DE: 5422 Ices
DE: 5470 Surface materials and properties
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting