Influence of surface morphology on the mid-infrared spectra of minerals and rocks

Abstract

The surface morphology of most of the airless planetary objects is characterized by the covering of a regolith blanket. Particle size, grain shape, particle size distribution, the degree of covering and porosity of this fine-grained material have a strong influence on thethermal troughput and the spectral behavior in the mid-infrared. Laboratory spectral emittance of particulate minerals was measured atwavelengths from 5 to 25 m to study the variation of diagnostic features with particle size and packing density. The experiments showed that in spectra of mineral powders with small grain sizes weakovertone and combination tone bands increasingly important for the identification of minerals instead of the vanishing fundamentals. Thechances for compositional analysis and complications in remote sensing aspplications are discussed.