Effect of composition on IR spectra of synthetic amorphous silicate cosmic dust analogues

Synthetic amorphous silicate dust samples were produced with various metal to silicon and iron to magnesium ratios to serve as analogues to cosmic dust. The IR spectra of the dusts were measured in the 10 and 20 μ m bands to determine the effect of composition on these characteristic features. Silicate dusts were produced with only Mg and Fe cations, and also with Mg, Fe. Na, Ca and Al cations in their relative cosmic ratio to study the spectral effects of varying silicate composition. The spectral results are compatible with the condensation of cosmic silicate grains as amorphous grains containing the major metals in their relative cosmic proportions. i.e. without chemical fractionation.