The authors have attempted to assess the disagreement of various investigators on the optical properties of germanium in the far uv. The analyis subjected the reported data, out to about 25 eV, to the following tests: (1) an internal consistency check when possible by applying the Kronig-Kramers dispersion relations to the optical constants; (2) an evaluation of the optical oscillator strength distribution for the spectrum under study; (3) correlation of the values of Im(l/∊*) from the optical data with the characteristic electron energy loss spectrum for the material; and (4) evaluation of the oscillator strength sum for the electron energy loss distribution. A set of optical constants derived from the characteristic electron energy loss data is presented and discussed. Also, an estimate of the source of errors incurred in the application of the Kronig-Kramers dispersion relations are given and discussed in terms of optical data.
R. E. LaVilla and H. Mendlowitz, "Optical Constants of Germanium," Appl. Opt. 6, 61-68 (1967)