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Paper: Thermal Emission Spectroscopy of Laboratory Regoliths
Volume: 196, Thermal Emission Spectroscopy and Analysis of Dust, Disks, and Regoliths
Page: 233
Authors: Wagner, C.
Abstract: The interpretation of emission spectra of planetary objects requires laboratory measurements for comparison. Emissivity measurements carried out at atmospheric pressure give not always a true analogue for the actual spectra of airless planetary objects, but they still provide valuable and practically indispensable results. The present study provides emissivity spectra of ten feldspars in the wavelength range from 6.3 to 17.5 μm, in dependence on the samples' grain size. The grain size is varied in the range from < 25 to 180 μm. Moreover, emissivity spectra are given for several binary mixtures of feldspar and pyroxene. It was found that linear mixing (i.e., linear combination of the component spectra, according to the components' volume percentages) provides a good approximation for the measured mixture spectrum. This was found not only for the wet-sieved coarser grain size fractions, where reflectance and emittance are dominated by surface scattering, but also for the grain size fractions < 63 μm, whose spectra reveal a significant contribution of volume scattering, and where the mixing was therefore expected to be nonlinear.
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