Optical Constants of Germanium in the Region 0-27 ev

The reflectivity $R$ has been measured for Ge crystal over the energy range 7.6-18.0 ev and the transmissivity $T$ for an evaporated Ge film over the range 16.6-27.4 ev. The reflectivity data near normal incidence, combined with existing data at lower energies, were used in the Kramers-Krönig dispersion relation to evaluate the index of refraction $n$ and extinction coefficient $k$ of Ge over the range 0-18 ev. Electron characteristic losses are predicted at 10 and 15 ev, consistent with those observed at 11 and 16 ev. The plasma frequency of bulk Ge as determined by the optical data is $\hslash \omega =10\mathrm{}$ ev.