The optical properties of trigonal selenium single crystals between 4 and 14.4 eV have been determined for radiation polarized parallel to (E‖c) and perpendicular to (E⊥c) the c axis of the crystal. A Kramers-Kronig analysis of the room-temperature specular-reflectivity data yielded the real (n) and imaginary (k) parts of the complex index of refraction, the real (ε1) and imaginary (ε2) parts of the complex dielectric constant, the absorption coefficient (α), and the energy-loss function (-Imε-1) over this energy range for both E‖c and E⊥c.
ALGIRD G. LEIGA, "Optical Properties of Trigonal Selenium in the Vacuum Ultraviolet," J. Opt. Soc. Am. 58, 880-883 (1968)