Infrared spectra of Mg-SiO smokes : comparison with analytical electron microscopy studies

Nuth, Joseph A., Rietmeijer, Frans J.M., Mackinnon, Ian D.R., & Sanford, Scott A. (1985) Infrared spectra of Mg-SiO smokes : comparison with analytical electron microscopy studies. In Lunar and Planetary Science Conference, Lunar and Planetary Institute, Houston, Texas, USA, pp. 623-624.

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Abstract

An important component of current models for interstellar and circumstellar evolution is the infrared (IR)spectral data collected from stellar outflows around oxygen-rich stars and from the general interstellar medium [1]. IR spectra from these celestial bodies are usually interpreted as showing the general properties of sub-micron sized silicate grains [2]. Two major features at 10 and 20 microns are reasonably attributed to amorphous olivine or pyroxene (e.g. Mg2Si04 or MgSi03) on the basis of comparisons with natural standards and vapor condensed silicates [3-6]. In an attempt to define crystallisation rates for spectrally amorphous condensates, Nuth and Donn [5] annealed experimentally produced amorphous magnesium silicate smokes at 1000K. On analysing these smokes at various annealing times, Nuth and Donn [5] showed that changes in crystallinity measured by bulk X-ray diffraction occured at longer annealing times (days) than changes measured by IR spectra (a few hours). To better define the onset of crystallinity in these magnesium silicates, we have examined each annealed product using a JEOL 1OOCX analytical electron microscope (AEM). In addition, the development of chemical diversity with annealing has been monitored using energy dispersive spectroscopy of individual grains from areas <20nm in diameter. Furthermore, the crystallisation kinetics of these smokes under ambient, room temperature conditions have been examined using bulk and fourier transform infrared (FTIR)spectra.

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ID Code: 55658
Item Type: Conference Paper
Refereed: Yes
Additional Information: GeoRef, Copyright 2009, American Geological Institute.
2008-008668
Keywords: amorphous materials, condensation, cosmic dust, electron microscopy data, experimental studies, infrared spectra, magnesian silicates, silicates, spectra, stars, three-dimensional models, ultrastructure
Subjects: Australian and New Zealand Standard Research Classification > EARTH SCIENCES (040000) > GEOLOGY (040300) > Extraterrestrial Geology (040302)
Australian and New Zealand Standard Research Classification > EARTH SCIENCES (040000) > GEOLOGY (040300) > Mineralogy and Crystallography (040306)
Divisions: Current > Institutes > Institute for Future Environments
Copyright Owner: Copyright 1985 Lunar and Planetary Institute
Deposited On: 21 Jan 2013 01:45
Last Modified: 10 Apr 2013 16:43

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