Infrared Extinction of Amorphous Iron Silicates

Abstract

Amorphous films with the compositions FeSiO<SUB>3</SUB> and Fe<SUB>2</SUB>SiO<SUB>4</SUB> were condensed by the reactive sputtering of FeSi and Fe<SUB>2</SUB>Si. Optical constants for these materials in the region 7-300 μm are presented. The extinction peaks are placed similarly to those of the analogous Mg , but the extinction efficiencies are down from 30% to 75%. Far-infrared (100-300 μm) measurements on Fe silicate thin films and those of the Mg analogs show extinction varying as ∼λ<SUP>-1.8</SUP>.