An ellipsometric investigation of the optical properties of Ru$_{2}$Ge$_{3}$ and Ru$_{2}$Sn$_{3}$ compounds

Ellipsometric investigations of the optical properties of Ru$_{2}$Ge$_{3}$ and Ru$_{2}$Sn$_{3}$ intermetallic compounds are carried out in the wavelength range from 0.22 to 15 $\mu$m. The nature of interband light absorption is analyzed based on a comparative analysis of the experimental and theoretical frequency dependences of an optical conductivity. The obtained results confirm the existence of energy gaps at the Fermi level in the electronic spectra of these materials predicted earlier by the band-structure calculations.