Absorptivity of Single-Crystal Yttrium at 4.2 K

Measurements of the absorptivity of single crystals of Y were made between 0.15 and 4.4 eV at 4.2 K. Polarized radiation was used with the electric vector parallel or perpendicular to the $\hat{c}$ axis of the crystal. The observed structures in the absorptivity were interpreted on the basis of band calculations for Sc, Re, and Gd and qualitative agreement was found between the band structures and the observed spectra.