37th DPS Meeting, 4-9 September 2005
Session 59 Laboratory Research
Poster, Thursday, September 8, 2005, 6:00-7:15pm, Music Recital Room

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[59.06] Optical Properties of Illite from 0.2 to 25 Microns: Extension into Mid-IR Region

P.S. Tuminello, E.T. Arakawa (University of Tennessee, Knoxville), B.N. Khare, D.P. Cruikshank, C.P. McKay, B. Tran (NASA Ames Research Center)

Illite is a clay mineral that is intermediate in composition and structure between muscovite and montmorillonite. Illite and other clay minerals were present in the primordial Earth and are believed to have played a role, although perhaps minor because of their limited distribution, in the catalysis of the polymeric compounds from which life emerged. Bernal proposed that clays may have played a role in the early stages of prebiological evolution by adsorbing organic micromolecules and acting as the host for the reactants necessary for the formation of biologically important macromolecules, protecting these reactants from the destructive action of ultraviolet light, and catalyzing polymers that would become other catalysts [Rao et al., J. Mol. Evol. 15, 317 (1980), Ponnamperuma et al., Origins of Life 12, 9 (1982)].

Over the past decades we have measured the optical constants of a variety of materials over wide spectral ranges: tholins, HCN polymer, solid and liquid hydrocarbons, ovalbumin, horseradish peroxidase, DNA, amino acid bases, bacterial spores (B. cereus, B. subtilis, B. anthracis, E. herbicola), kerogens, Murchison meteorite, kaolinite, montmorillonite, and illite. Previously we presented results of our measurements the optical constants of illite from 0.2 to 2.5 micrometers. We have extended those measurements into the mid-IR to 25 micrometers using pressed pellets of illite in KBr. Our new optical constants in the IR will allow illite to be used as a material choice in modeling studies of dust in the Mars atmosphere, and of surfaces of outer Solar System bodies such as Phoebe and Iapetus where hydrated silicates are present.

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Bulletin of the American Astronomical Society, 37 #3
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