Optical Properties of Single-Crystal Be from 0.12 to 4.5 eV

Measurements of the optical absorptivity of single crystals of Be have been carried out in the energy range 0.12-4.5 eV with polarized light. The infrared absorptivity is considerably lower than previously reported. Evidence is presented for the onset of interband transitions for both polarizations beginning near 0.4 eV. A shoulder is noted in the absorptivity for $\mathrm{E}\perp c$ at about 1.3 eV. The absorptivity data are Kramers-Kronig analyzed and the optical constants are determined. An interpretation based on the band structure of Tripp, Everett, Gordon, and Stark is presented.