16-80 mum spectra of crystalline silicates at 4 K, 80 K and 295 K

Bowey, J. E., Lee, C., Tucker, C. ORCID: https://orcid.org/0000-0002-1851-3918, Hofmeister, A. M. and Ade, P. A. R. ORCID: https://orcid.org/0000-0002-5127-0401 2000. 16-80 mum spectra of crystalline silicates at 4 K, 80 K and 295 K. Presented at: 2nd ISO Workshop on Analytical Spectroscopy, Madrid, Spain, 02-04 February 2000. ISO beyond the peaks: The 2nd ISO workshop on analytical spectroscopy. ESA, p. 339.

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Abstract

Far-infrared laboratory spectra are normally taken at room temperature. However, the grains responsible for the 〉20 μm silicate emission bands in ISO spectra are at temperatures below ~ 150 K. Therefore we are conducting a comparative study of the absorption spectra of crystalline olivines, pyroxenes and hydrous silicates at 4 K, 80 K and at room temperature (295 K). Many bands become narrower and some bands split at cryogenic temperatures. Therefore, to resolve fine structure at 4 K the resolution must be increased to 0.25 cm^-1 whilst 2 cm^-1 resolution is adequate at 295 K. In general, 295 K bands are shifted to shorter wavelengths at 4 K; the magnitude of the shift increases with wavelength from ~ 0.1-0.2 μm for peaks near 25 μm to nearly ~ 1 μm for peaks between 70 and 80 μm. However, neighbouring bands are shifted by different amounts and the shift pattern varies between mineral groups. A ~ 80 K forsterite spectrum indicates that the 295 K-to-80 K wavelength shifts are smaller than the 295 K-to-4 K shift. Further measurements are being undertaken.

Item Type:	Conference or Workshop Item (Paper)
Date Type:	Published Online
Status:	Published
Schools:	Physics and Astronomy
Publisher:	ESA
Last Modified:	12 May 2023 14:45
URI:	https://orca.cardiff.ac.uk/id/eprint/156780

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