Optical Properties of Diamond in the Vacuum Ultraviolet

The optical constants of diamond have been determined in the range 5.5 to 23 eV by applying the Kramers-Kronig relation to normal incidence reflectance data. There are two salient features in the curve for optical absorption. First, the absorption rises rapidly near 7 eV, indicating the onset of strong direct transitions. Second, a relatively sharp peak occurs near 12.5 eV. These data are discussed in terms of the energy band picture for diamond and related materials which have a similar band structure.